* [PATCH v6 05/15] digest_cache: Add securityfs interface
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Create the digest_cache directory in <securityfs>/integrity, and add the
default_path file, to let root change/read the default path (file or
directory) from where digest lists are looked up.
An RW semaphore prevents the default path from changing while
digest_list_new() and read_default_path() are executed, so that those read
a stable value. Multiple digest_list_new() and read_default_path() calls,
instead, can be done in parallel, since they are the readers.
Changing the default path does not affect digest caches created with the
old path.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/digest_cache/Kconfig | 4 +
security/integrity/digest_cache/Makefile | 2 +-
security/integrity/digest_cache/internal.h | 4 +
security/integrity/digest_cache/main.c | 10 +-
security/integrity/digest_cache/secfs.c | 104 +++++++++++++++++++++
security/integrity/ima/ima_fs.c | 6 ++
6 files changed, 128 insertions(+), 2 deletions(-)
create mode 100644 security/integrity/digest_cache/secfs.c
diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig
index 81f9d4ae749f..a4bfa8287b8d 100644
--- a/security/integrity/digest_cache/Kconfig
+++ b/security/integrity/digest_cache/Kconfig
@@ -17,3 +17,7 @@ config DIGEST_LIST_DEFAULT_PATH
help
Default path where the Integrity Digest Cache expects to find digest
lists.
+
+ It can be changed at run-time, by writing the new path to the
+ securityfs interface. Digest caches created with the old path are
+ not affected by the change.
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index 6a3f7cc6e106..c351186d4e1e 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -4,4 +4,4 @@
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o
+digest_cache-y := main.o secfs.o
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index 29bf98a974f3..82d9c894c8fc 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -52,6 +52,7 @@ struct digest_cache_security {
extern loff_t inode_sec_offset;
extern loff_t file_sec_offset;
extern char *default_path_str;
+extern struct rw_semaphore default_path_sem;
static inline struct digest_cache_security *
digest_cache_get_security_from_blob(void *inode_security)
@@ -121,4 +122,7 @@ struct digest_cache *digest_cache_init(struct dentry *dentry,
int __init digest_cache_do_init(const struct lsm_id *lsm_id,
loff_t inode_offset, loff_t file_offset);
+/* secfs.c */
+int __init digest_cache_secfs_init(struct dentry *dir);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index 6e94cff2b0dc..6724471914da 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -21,6 +21,9 @@ loff_t file_sec_offset;
char *default_path_str = CONFIG_DIGEST_LIST_DEFAULT_PATH;
+/* Protects default_path_str. */
+struct rw_semaphore default_path_sem;
+
/**
* digest_cache_alloc_init - Allocate and initialize a new digest cache
* @path_str: Path string of the digest list
@@ -321,9 +324,12 @@ struct digest_cache *digest_cache_get(struct file *file)
/* Serialize accesses to inode for which the digest cache is used. */
mutex_lock(&dig_sec->dig_user_mutex);
- if (!dig_sec->dig_user)
+ if (!dig_sec->dig_user) {
+ down_read(&default_path_sem);
/* Consume extra reference from digest_cache_create(). */
dig_sec->dig_user = digest_cache_new(dentry, &digest_list_path);
+ up_read(&default_path_sem);
+ }
if (dig_sec->dig_user)
/* Increment ref. count for reference returned to the caller. */
@@ -439,6 +445,8 @@ static struct security_hook_list digest_cache_hooks[] __ro_after_init = {
int __init digest_cache_do_init(const struct lsm_id *lsm_id,
loff_t inode_offset, loff_t file_offset)
{
+ init_rwsem(&default_path_sem);
+
inode_sec_offset = inode_offset;
file_sec_offset = file_offset;
diff --git a/security/integrity/digest_cache/secfs.c b/security/integrity/digest_cache/secfs.c
new file mode 100644
index 000000000000..f158233f3492
--- /dev/null
+++ b/security/integrity/digest_cache/secfs.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the securityfs interface of the Integrity Digest Cache.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include <linux/security.h>
+
+#include "internal.h"
+
+static struct dentry *digest_cache_dir;
+static struct dentry *default_path_dentry;
+
+/**
+ * write_default_path - Write default path
+ * @file: File descriptor of the securityfs file
+ * @buf: User space buffer
+ * @datalen: Amount of data to write
+ * @ppos: Current position in the file
+ *
+ * This function sets the new default path where digest lists can be found.
+ * Can be either a regular file or a directory.
+ *
+ * Return: Length of path written on success, a POSIX error code otherwise.
+ */
+static ssize_t write_default_path(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ char *new_default_path_str;
+
+ new_default_path_str = memdup_user_nul(buf, datalen);
+ if (IS_ERR(new_default_path_str))
+ return PTR_ERR(new_default_path_str);
+
+ down_write(&default_path_sem);
+ kfree_const(default_path_str);
+ default_path_str = new_default_path_str;
+ up_write(&default_path_sem);
+ return datalen;
+}
+
+/**
+ * read_default_path - Read default path
+ * @file: File descriptor of the securityfs file
+ * @buf: User space buffer
+ * @datalen: Amount of data to read
+ * @ppos: Current position in the file
+ *
+ * This function returns the current default path where digest lists can be
+ * found. Can be either a regular file or a directory.
+ *
+ * Return: Length of path read on success, a POSIX error code otherwise.
+ */
+static ssize_t read_default_path(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ int ret;
+
+ down_read(&default_path_sem);
+ ret = simple_read_from_buffer(buf, datalen, ppos, default_path_str,
+ strlen(default_path_str) + 1);
+ up_read(&default_path_sem);
+ return ret;
+}
+
+static const struct file_operations default_path_ops = {
+ .open = generic_file_open,
+ .write = write_default_path,
+ .read = read_default_path,
+ .llseek = generic_file_llseek,
+};
+
+/**
+ * digest_cache_secfs_init - Initialize the securityfs interface
+ * @dir: Directory entry provided by the calling LSM
+ *
+ * This function initializes the securityfs interfaces, for configuration
+ * by user space.
+ *
+ * It creates 'default_path', allowing user space to change the default
+ * directory where digest lists are searched.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int __init digest_cache_secfs_init(struct dentry *dir)
+{
+ digest_cache_dir = securityfs_create_dir("digest_cache", dir);
+ if (IS_ERR(digest_cache_dir))
+ return PTR_ERR(digest_cache_dir);
+
+ default_path_dentry = securityfs_create_file("default_path", 0660,
+ digest_cache_dir, NULL,
+ &default_path_ops);
+ if (IS_ERR(default_path_dentry)) {
+ securityfs_remove(digest_cache_dir);
+ return PTR_ERR(default_path_dentry);
+ }
+
+ return 0;
+}
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index e4a79a9b2d58..be9e374e2cef 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -614,6 +614,12 @@ int __init ima_fs_init(void)
goto out;
}
+ if (IS_ENABLED(CONFIG_INTEGRITY_DIGEST_CACHE)) {
+ ret = digest_cache_secfs_init(integrity_dir);
+ if (ret < 0)
+ goto out;
+ }
+
return 0;
out:
securityfs_remove(ima_policy);
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 06/15] digest_cache: Add hash tables and operations
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add a linked list of hash tables to the digest cache, one per algorithm,
containing the digests extracted from digest lists.
The number of hash table slots is determined by dividing the number of
digests to add to the average depth of the collision list defined with
CONFIG_DIGEST_CACHE_HTABLE_DEPTH (currently set to 30). It can be changed
in the kernel configuration.
Add digest_cache_htable_init(), digest_cache_htable_add() and
digest_cache_htable_lookup() to the Parser API, so that digest list parsers
can allocate the hash tables and add/lookup extracted digests.
Add digest_cache_htable_free(), to let the Integrity Digest Cache free the
hash tables at the time a digest cache is freed.
Add digest_cache_lookup() to the Client API, to let users of the Integrity
Digest Cache search a digest in a digest cache and, in a subsequent patch,
to search it in the digest caches for each directory entry.
digest_cache_lookup() returns a digest cache reference that must be
released by calling digest_cache_put().
Finally, introduce digest_cache_hash_key() to compute the hash table key
from the first two bytes of the digest (modulo the number of slots).
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/linux/digest_cache.h | 39 ++++
security/integrity/digest_cache/Kconfig | 11 +
security/integrity/digest_cache/Makefile | 2 +-
security/integrity/digest_cache/htable.c | 251 +++++++++++++++++++++
security/integrity/digest_cache/internal.h | 36 +++
security/integrity/digest_cache/main.c | 3 +
6 files changed, 341 insertions(+), 1 deletion(-)
create mode 100644 security/integrity/digest_cache/htable.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index 1f88b61fb7cd..59a42c04cbb8 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -11,12 +11,25 @@
#define _LINUX_DIGEST_CACHE_H
#include <linux/fs.h>
+#include <crypto/hash_info.h>
#ifdef CONFIG_INTEGRITY_DIGEST_CACHE
/* Client API */
struct digest_cache *digest_cache_get(struct file *file);
void digest_cache_put(struct digest_cache *digest_cache);
bool digest_cache_opened_fd(struct file *file);
+struct digest_cache *digest_cache_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo);
+
+/* Parser API */
+int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
+ enum hash_algo algo);
+int digest_cache_htable_add(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
+int digest_cache_htable_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
#else
static inline struct digest_cache *digest_cache_get(struct file *file)
@@ -33,5 +46,31 @@ static inline bool digest_cache_opened_fd(struct file *file)
return false;
}
+static inline struct digest_cache *
+digest_cache_lookup(struct dentry *dentry, struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ return NULL;
+}
+
+static inline int digest_cache_htable_init(struct digest_cache *digest_cache,
+ u64 num_digests, enum hash_algo algo)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int digest_cache_htable_add(struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int digest_cache_htable_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ return -EOPNOTSUPP;
+}
+
#endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig
index a4bfa8287b8d..419011fb52c9 100644
--- a/security/integrity/digest_cache/Kconfig
+++ b/security/integrity/digest_cache/Kconfig
@@ -21,3 +21,14 @@ config DIGEST_LIST_DEFAULT_PATH
It can be changed at run-time, by writing the new path to the
securityfs interface. Digest caches created with the old path are
not affected by the change.
+
+config DIGEST_CACHE_HTABLE_DEPTH
+ int
+ default 30
+ help
+ Desired average depth of the collision list in the digest cache
+ hash tables.
+
+ A smaller number will increase the amount of hash table slots, and
+ make the search faster. A bigger number will decrease the number of
+ hash table slots, but make the search slower.
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index c351186d4e1e..0092c913979d 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -4,4 +4,4 @@
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o
+digest_cache-y := main.o secfs.o htable.o
diff --git a/security/integrity/digest_cache/htable.c b/security/integrity/digest_cache/htable.c
new file mode 100644
index 000000000000..8aa6d50a0cb5
--- /dev/null
+++ b/security/integrity/digest_cache/htable.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement hash table operations for the digest cache.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include "internal.h"
+
+/**
+ * digest_cache_hash_key - Compute hash key
+ * @digest: Digest cache
+ * @num_slots: Number of slots in the hash table
+ *
+ * This function computes a hash key based on the first two bytes of the
+ * digest and the number of slots of the hash table.
+ *
+ * Return: Hash key.
+ */
+static inline unsigned int digest_cache_hash_key(u8 *digest,
+ unsigned int num_slots)
+{
+ /* Same as ima_hash_key() but parametrized. */
+ return (digest[0] | digest[1] << 8) % num_slots;
+}
+
+/**
+ * lookup_htable - Lookup a hash table
+ * @digest_cache: Digest cache
+ * @algo: Algorithm of the desired hash table
+ *
+ * This function searches the hash table for a given algorithm in the digest
+ * cache.
+ *
+ * Return: A hash table if found, NULL otherwise.
+ */
+static struct htable *lookup_htable(struct digest_cache *digest_cache,
+ enum hash_algo algo)
+{
+ struct htable *h;
+
+ list_for_each_entry(h, &digest_cache->htables, next)
+ if (h->algo == algo)
+ return h;
+
+ return NULL;
+}
+
+/**
+ * digest_cache_htable_init - Allocate and initialize the hash table
+ * @digest_cache: Digest cache
+ * @num_digests: Number of digests to add to the hash table
+ * @algo: Algorithm of the digests
+ *
+ * This function allocates and initializes the hash table for a given algorithm.
+ * The number of slots depends on the number of digests to add to the digest
+ * cache, and the constant CONFIG_DIGEST_CACHE_HTABLE_DEPTH stating the desired
+ * average depth of the collision list.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
+ enum hash_algo algo)
+{
+ struct htable *h;
+ unsigned int i;
+
+ if (!num_digests)
+ return -EINVAL;
+
+ h = lookup_htable(digest_cache, algo);
+ if (h)
+ return 0;
+
+ h = kmalloc(sizeof(*h), GFP_KERNEL);
+ if (!h)
+ return -ENOMEM;
+
+ h->num_slots = DIV_ROUND_UP(num_digests,
+ CONFIG_DIGEST_CACHE_HTABLE_DEPTH);
+ h->slots = kmalloc_array(h->num_slots, sizeof(*h->slots), GFP_KERNEL);
+ if (!h->slots) {
+ kfree(h);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < h->num_slots; i++)
+ INIT_HLIST_HEAD(&h->slots[i]);
+
+ h->num_digests = 0;
+ h->algo = algo;
+
+ list_add_tail(&h->next, &digest_cache->htables);
+
+ pr_debug("Initialized hash table for digest list %s, digests: %llu, slots: %u, algo: %s\n",
+ digest_cache->path_str, num_digests, h->num_slots,
+ hash_algo_name[algo]);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(digest_cache_htable_init);
+
+/**
+ * digest_cache_htable_add - Add a new digest to the digest cache
+ * @digest_cache: Digest cache
+ * @digest: Digest to add
+ * @algo: Algorithm of the digest
+ *
+ * This function adds a digest extracted from a digest list to the digest cache.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_htable_add(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct htable *h;
+ struct digest_cache_entry *entry;
+ unsigned int key;
+ int digest_len;
+
+ h = lookup_htable(digest_cache, algo);
+ if (!h) {
+ pr_debug("No hash table for algorithm %s was found in digest cache %s, initialize one\n",
+ hash_algo_name[algo], digest_cache->path_str);
+ return -ENOENT;
+ }
+
+ digest_len = hash_digest_size[algo];
+
+ entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ memcpy(entry->digest, digest, digest_len);
+
+ key = digest_cache_hash_key(digest, h->num_slots);
+ hlist_add_head(&entry->hnext, &h->slots[key]);
+ h->num_digests++;
+ pr_debug("Added digest %s:%*phN to digest cache %s, num of %s digests: %llu\n",
+ hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str, hash_algo_name[algo], h->num_digests);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(digest_cache_htable_add);
+
+/**
+ * digest_cache_htable_lookup - Search a digest in the digest cache
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function searches the passed digest and algorithm in the digest cache.
+ *
+ * Return: Zero if the digest is found, a POSIX error code otherwise.
+ */
+int digest_cache_htable_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct digest_cache_entry *entry;
+ struct htable *h;
+ unsigned int key;
+ int digest_len = hash_digest_size[algo];
+ int search_depth = 0, ret = -ENOENT;
+
+ h = lookup_htable(digest_cache, algo);
+ if (!h)
+ goto out;
+
+ key = digest_cache_hash_key(digest, h->num_slots);
+
+ hlist_for_each_entry(entry, &h->slots[key], hnext) {
+ if (!memcmp(entry->digest, digest, digest_len)) {
+ pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest cache %s\n",
+ search_depth, dentry->d_name.name,
+ hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str);
+
+ return 0;
+ }
+
+ search_depth++;
+ }
+out:
+ pr_debug("Cache miss for file %s, digest %s:%*phN not in digest cache %s\n",
+ dentry->d_name.name, hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(digest_cache_htable_lookup);
+
+/**
+ * digest_cache_lookup - Search a digest in the digest cache
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function calls digest_cache_htable_lookup() to search a digest in the
+ * passed digest cache, obtained with digest_cache_get().
+ *
+ * Return: A digest cache reference the digest is found, NULL if not.
+ */
+struct digest_cache *digest_cache_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ int ret;
+
+ ret = digest_cache_htable_lookup(dentry, digest_cache, digest, algo);
+ if (ret < 0)
+ return NULL;
+
+ return digest_cache_ref(digest_cache);
+}
+EXPORT_SYMBOL_GPL(digest_cache_lookup);
+
+/**
+ * digest_cache_htable_free - Free the hash tables
+ * @digest_cache: Digest cache
+ *
+ * This function removes all digests from all hash tables in the digest cache,
+ * and frees the memory.
+ */
+void digest_cache_htable_free(struct digest_cache *digest_cache)
+{
+ struct htable *h, *h_tmp;
+ struct digest_cache_entry *p;
+ struct hlist_node *q;
+ unsigned int i;
+
+ list_for_each_entry_safe(h, h_tmp, &digest_cache->htables, next) {
+ for (i = 0; i < h->num_slots; i++) {
+ hlist_for_each_entry_safe(p, q, &h->slots[i], hnext) {
+ hlist_del(&p->hnext);
+ pr_debug("Removed digest %s:%*phN from digest cache %s\n",
+ hash_algo_name[h->algo],
+ hash_digest_size[h->algo], p->digest,
+ digest_cache->path_str);
+ kfree(p);
+ }
+ }
+
+ list_del(&h->next);
+ kfree(h->slots);
+ kfree(h);
+ }
+}
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index 82d9c894c8fc..e14343e96caa 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -18,8 +18,40 @@
#define INIT_STARTED 1 /* Digest cache init started. */
#define INVALID 2 /* Digest cache marked as invalid. */
+/**
+ * struct digest_cache_entry - Entry of a digest cache hash table
+ * @hnext: Pointer to the next element in the collision list
+ * @digest: Stored digest
+ *
+ * This structure represents an entry of a digest cache hash table, storing a
+ * digest.
+ */
+struct digest_cache_entry {
+ struct hlist_node hnext;
+ u8 digest[];
+};
+
+/**
+ * struct htable - Hash table
+ * @next: Next hash table in the linked list
+ * @slots: Hash table slots
+ * @num_slots: Number of slots
+ * @num_digests: Number of digests stored in the hash table
+ * @algo: Algorithm of the digests
+ *
+ * This structure is a hash table storing digests of file data or metadata.
+ */
+struct htable {
+ struct list_head next;
+ struct hlist_head *slots;
+ unsigned int num_slots;
+ u64 num_digests;
+ enum hash_algo algo;
+};
+
/**
* struct digest_cache - Digest cache
+ * @htables: Hash tables (one per algorithm)
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
@@ -27,6 +59,7 @@
* This structure represents a cache of digests extracted from a digest list.
*/
struct digest_cache {
+ struct list_head htables;
atomic_t ref_count;
char *path_str;
unsigned long flags;
@@ -125,4 +158,7 @@ int __init digest_cache_do_init(const struct lsm_id *lsm_id,
/* secfs.c */
int __init digest_cache_secfs_init(struct dentry *dir);
+/* htable.c */
+void digest_cache_htable_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index 6724471914da..ebc5dc09a62b 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -51,6 +51,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
atomic_set(&digest_cache->ref_count, 1);
digest_cache->flags = 0UL;
+ INIT_LIST_HEAD(&digest_cache->htables);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -66,6 +67,8 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
*/
static void digest_cache_free(struct digest_cache *digest_cache)
{
+ digest_cache_htable_free(digest_cache);
+
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
kmem_cache_free(digest_cache_cache, digest_cache);
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 07/15] digest_cache: Allow registration of digest list parsers
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Allow kernel modules to register/deregister new digest list parsers,
respectively through digest_cache_register_parser() and
digest_cache_unregister_parser().
Those functions pass the new parser structure holding the linked list
pointers and a parsing function with the new type parser_func.
Introduce digest_cache_parse_digest_list(), which determines the desired
parser from the file name, looks up the parser among the registered ones
with lookup_get_parser(), calls the parser-specific function along with the
digest list data read by the kernel, and finally releases the kernel module
reference with put_parser().
The expected digest list file name format is:
[<seq num>-]<digest list format>-<digest list name>
<seq-num>- is an optional prefix to impose in which order digest lists in
a directory should be parsed.
Introduce load_parser() to load a kernel module containing a
parser for the requested digest list format (compressed kernel modules are
supported). Kernel modules are searched in the
/lib/modules/<kernel ver>/security/integrity/digest_cache directory.
load_parser() calls ksys_finit_module() to load a kernel module directly
from the kernel. request_module() cannot be used at this point, since the
reference digests of modprobe and the linked libraries (required for IMA
appraisal) might not be yet available, resulting in modprobe execution
being denied.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/linux/digest_cache.h | 38 +++
security/integrity/digest_cache/Kconfig | 1 +
security/integrity/digest_cache/Makefile | 4 +-
security/integrity/digest_cache/internal.h | 5 +
security/integrity/digest_cache/parsers.c | 257 +++++++++++++++++++++
5 files changed, 304 insertions(+), 1 deletion(-)
create mode 100644 security/integrity/digest_cache/parsers.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index 59a42c04cbb8..a9d731990b7c 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -13,6 +13,32 @@
#include <linux/fs.h>
#include <crypto/hash_info.h>
+struct digest_cache;
+
+/**
+ * typedef parser_func - Function to parse digest lists
+ *
+ * Define a function type to parse digest lists.
+ */
+typedef int (*parser_func)(struct digest_cache *digest_cache, const u8 *data,
+ size_t data_len);
+
+/**
+ * struct parser - Structure to store a function pointer to parse digest list
+ * @list: Linked list
+ * @owner: Kernel module owning the parser
+ * @name: Parser name (must match the format in the digest list file name)
+ * @func: Function pointer for parsing
+ *
+ * This structure stores a function pointer to parse a digest list.
+ */
+struct parser {
+ struct list_head list;
+ struct module *owner;
+ const char name[NAME_MAX + 1];
+ parser_func func;
+};
+
#ifdef CONFIG_INTEGRITY_DIGEST_CACHE
/* Client API */
struct digest_cache *digest_cache_get(struct file *file);
@@ -30,6 +56,8 @@ int digest_cache_htable_add(struct digest_cache *digest_cache, u8 *digest,
int digest_cache_htable_lookup(struct dentry *dentry,
struct digest_cache *digest_cache, u8 *digest,
enum hash_algo algo);
+int digest_cache_register_parser(struct parser *parser);
+void digest_cache_unregister_parser(struct parser *parser);
#else
static inline struct digest_cache *digest_cache_get(struct file *file)
@@ -72,5 +100,15 @@ static inline int digest_cache_htable_lookup(struct dentry *dentry,
return -EOPNOTSUPP;
}
+static inline int digest_cache_register_parser(const char *name,
+ parser_func func)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void digest_cache_unregister_parser(const char *name)
+{
+}
+
#endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig
index 419011fb52c9..65c07110911b 100644
--- a/security/integrity/digest_cache/Kconfig
+++ b/security/integrity/digest_cache/Kconfig
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
config INTEGRITY_DIGEST_CACHE
bool "Integrity Digest Cache"
+ select MODULE_DECOMPRESS if MODULE_COMPRESS
default n
help
This option enables a cache of reference digests (e.g. of file
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index 0092c913979d..d68cae690241 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -4,4 +4,6 @@
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o htable.o
+digest_cache-y := main.o secfs.o htable.o parsers.o
+
+CFLAGS_parsers.o += -DPARSERS_DIR=\"$(MODLIB)/kernel/security/integrity/digest_cache/parsers\"
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index e14343e96caa..e178549f9ff9 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -161,4 +161,9 @@ int __init digest_cache_secfs_init(struct dentry *dir);
/* htable.c */
void digest_cache_htable_free(struct digest_cache *digest_cache);
+/* parsers.c */
+int digest_cache_parse_digest_list(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ char *path_str, void *data, size_t data_len);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/parsers.c b/security/integrity/digest_cache/parsers.c
new file mode 100644
index 000000000000..744c9742a44e
--- /dev/null
+++ b/security/integrity/digest_cache/parsers.c
@@ -0,0 +1,257 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the code to register digest list parsers.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include <linux/init_task.h>
+#include <linux/namei.h>
+#include <uapi/linux/module.h>
+#include <linux/syscalls.h>
+#include <linux/vmalloc.h>
+
+#include "internal.h"
+
+static DEFINE_MUTEX(parsers_mutex);
+static LIST_HEAD(parsers);
+
+/**
+ * load_parser - Load kernel module containing a parser
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ * @digest_cache: Digest cache
+ * @name: Name of the parser to load
+ *
+ * This function opens a kernel module file in
+ * /lib/modules/<kernel ver>/security/integrity/digest_cache, and executes
+ * ksys_finit_module() to load the kernel module. After kernel module
+ * initialization, the parser should be found in the linked list of parsers.
+ *
+ * Return: Zero if kernel module is loaded, a POSIX error code otherwise.
+ */
+static int load_parser(struct dentry *dentry, struct digest_cache *digest_cache,
+ const char *name)
+{
+ char *compress_suffix = "";
+ char *parser_path;
+ struct file *file;
+ struct path path;
+ int ret = 0, flags = 0;
+
+ /* Must be kept in sync with kernel/module/Kconfig. */
+ if (IS_ENABLED(CONFIG_MODULE_COMPRESS_GZIP))
+ compress_suffix = ".gz";
+ else if (IS_ENABLED(CONFIG_MODULE_COMPRESS_XZ))
+ compress_suffix = ".xz";
+ else if (IS_ENABLED(CONFIG_MODULE_COMPRESS_ZSTD))
+ compress_suffix = ".zst";
+
+ if (strlen(compress_suffix))
+ flags |= MODULE_INIT_COMPRESSED_FILE;
+
+ parser_path = kasprintf(GFP_KERNEL, "%s/%s.ko%s", PARSERS_DIR, name,
+ compress_suffix);
+ if (!parser_path)
+ return -ENOMEM;
+
+ ret = kern_path(parser_path, 0, &path);
+ if (ret < 0) {
+ pr_debug("Cannot find path %s\n", parser_path);
+ goto out;
+ }
+
+ /* Cannot request a digest cache for the kernel module inode. */
+ if (d_backing_inode(dentry) == d_backing_inode(path.dentry)) {
+ pr_debug("Cannot request a digest cache for kernel module %s\n",
+ dentry->d_name.name);
+ ret = -EBUSY;
+ goto out;
+ }
+
+ file = kernel_file_open(&path, O_RDONLY, &init_cred);
+ if (IS_ERR(file)) {
+ pr_debug("Cannot open %s\n", parser_path);
+ ret = PTR_ERR(file);
+ goto out_path;
+ }
+
+ /* Mark the file descriptor as ours. */
+ digest_cache_to_file_sec(file, digest_cache);
+
+ ret = ksys_finit_module(file, "", flags);
+ if (ret < 0)
+ pr_debug("Cannot load module %s\n", parser_path);
+
+ fput(file);
+out_path:
+ path_put(&path);
+out:
+ kfree(parser_path);
+ return ret;
+}
+
+/**
+ * lookup_get_parser - Lookup and get parser among registered ones
+ * @name: Name of the parser to search
+ *
+ * This function searches a parser among the registered ones, and returns it
+ * to the caller, after incrementing the kernel module reference count.
+ *
+ * Must be called with parser_mutex held.
+ *
+ * Return: A parser structure if parser is found and available, NULL otherwise.
+ */
+static struct parser *lookup_get_parser(const char *name)
+{
+ struct parser *entry, *found = NULL;
+
+ list_for_each_entry(entry, &parsers, list) {
+ if (!strcmp(entry->name, name) &&
+ try_module_get(entry->owner)) {
+ found = entry;
+ break;
+ }
+ }
+
+ return found;
+}
+
+/**
+ * put_parser - Put parser
+ * @parser: Parser to put
+ *
+ * This function decreases the kernel module reference count.
+ */
+static void put_parser(struct parser *parser)
+{
+ module_put(parser->owner);
+}
+
+/**
+ * digest_cache_parse_digest_list - Parse a digest list
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ * @digest_cache: Digest cache
+ * @path_str: Path string of the digest list
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function selects a parser for a digest list depending on its file name,
+ * and calls the appropriate parsing function. It expects the file name to be
+ * in the format: [<seq num>-]<digest list format>-<digest list name>.
+ * <seq num>- is optional.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_parse_digest_list(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ char *path_str, void *data, size_t data_len)
+{
+ char *filename, *format, *next_sep;
+ struct parser *parser;
+ char format_buf[sizeof(parser->name)];
+ int ret = -EINVAL;
+
+ filename = strrchr(path_str, '/');
+ if (!filename)
+ return ret;
+
+ filename++;
+ format = filename;
+
+ /*
+ * Since we expect that all files start with a digest list format, this
+ * check is reliable to detect <seq num>.
+ */
+ if (filename[0] >= '0' && filename[0] <= '9') {
+ format = strchr(filename, '-');
+ if (!format)
+ return ret;
+
+ format++;
+ }
+
+ next_sep = strchr(format, '-');
+ if (!next_sep || next_sep - format >= sizeof(format_buf))
+ return ret;
+
+ snprintf(format_buf, sizeof(format_buf), "%.*s",
+ (int)(next_sep - format), format);
+
+ pr_debug("Parsing %s, format: %s, size: %ld\n", path_str, format_buf,
+ data_len);
+
+ mutex_lock(&parsers_mutex);
+ parser = lookup_get_parser(format_buf);
+ mutex_unlock(&parsers_mutex);
+
+ if (!parser) {
+ load_parser(dentry, digest_cache, format_buf);
+
+ mutex_lock(&parsers_mutex);
+ parser = lookup_get_parser(format_buf);
+ mutex_unlock(&parsers_mutex);
+
+ if (!parser) {
+ pr_debug("Digest list parser %s not found\n",
+ format_buf);
+ return -ENOENT;
+ }
+ }
+
+ ret = parser->func(digest_cache, data, data_len);
+ put_parser(parser);
+
+ return ret;
+}
+
+/**
+ * digest_cache_register_parser - Register new parser
+ * @parser: Parser structure to register
+ *
+ * This function searches the parser name among the registered ones and, if not
+ * found, appends the parser to the linked list of parsers.
+ *
+ * Return: Zero on success, -EEXIST if a parser with the same name exists.
+ */
+int digest_cache_register_parser(struct parser *parser)
+{
+ struct parser *p;
+ int ret = 0;
+
+ mutex_lock(&parsers_mutex);
+ p = lookup_get_parser(parser->name);
+ if (p) {
+ put_parser(p);
+ ret = -EEXIST;
+ goto out;
+ }
+
+ list_add_tail(&parser->list, &parsers);
+out:
+ pr_debug("Digest list parser \'%s\' %s registered\n", parser->name,
+ (ret < 0) ? "cannot be" : "successfully");
+
+ mutex_unlock(&parsers_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(digest_cache_register_parser);
+
+/**
+ * digest_cache_unregister_parser - Unregister parser
+ * @parser: Parser structure to unregister
+ *
+ * This function removes the passed parser from the linked list of parsers.
+ */
+void digest_cache_unregister_parser(struct parser *parser)
+{
+ mutex_lock(&parsers_mutex);
+ list_del(&parser->list);
+ mutex_unlock(&parsers_mutex);
+
+ pr_debug("Digest list parser \'%s\' successfully unregistered\n",
+ parser->name);
+}
+EXPORT_SYMBOL_GPL(digest_cache_unregister_parser);
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 08/15] digest_cache: Parse tlv digest lists
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add digest_list_parse_tlv(), to parse TLV-formatted (Type Length Value)
digest lists. Their structure is:
[field: DIGEST_LIST_ALGO, length, value]
[field: DIGEST_LIST_NUM_ENTRIES, length, value]
[field: DIGEST_LIST_ENTRY#1, length, value (below)]
|- [DIGEST_LIST_ENTRY_DIGEST#1, length, file digest]
|- [DIGEST_LIST_ENTRY_PATH#1, length, file path]
[field: DIGEST_LIST_ENTRY#N, length, value (below)]
|- [DIGEST_LIST_ENTRY_DIGEST#N, length, file digest]
|- [DIGEST_LIST_ENTRY_PATH#N, length, file path]
DIGEST_LIST_ALGO and DIGEST_LIST_NUM_ENTRIES must have a fixed length
respectively of sizeof(u16) and sizeof(u32).
The data of the DIGEST_LIST_ENTRY field are itself in TLV format, for which
the DIGEST_LIST_ENTRY_DIGEST and DIGEST_LIST_ENTRY_PATH fields are defined.
Currently defined fields are sufficient for measurement/appraisal of file
data. More fields will be introduced later for file metadata.
Introduce digest_list_callback() to handle the digest list fields,
DIGEST_LIST_ALGO, DIGEST_LIST_NUM_ENTRIES and DIGEST_LIST_ENTRY, and the
respective field parsers parse_digest_list_algo(),
parse_digest_list_num_entries() and parse_digest_list_entry().
Introduce digest_list_entry_callback(), to handle the DIGEST_LIST_ENTRY
fields, DIGEST_LIST_ENTRY_DIGEST and DIGEST_LIST_ENTRY_PATH, and the
respective field parsers parse_digest_list_entry_digest() and
parse_digest_list_entry_path().
The TLV parser itself is implemented in lib/tlv_parser.c.
Both the TLV parser and the tlv digest list parser have been formally
verified with Frama-C (https://frama-c.com/).
The analysis has been done on this file:
https://github.com/robertosassu/rpm-formal/blob/main/validate_tlv.c
Here is the result of the analysis:
[eva:summary] ====== ANALYSIS SUMMARY ======
---------------------------------------------------------------------------
12 functions analyzed (out of 12): 100% coverage.
In these functions, 177 statements reached (out of 191): 92% coverage.
---------------------------------------------------------------------------
Some errors and warnings have been raised during the analysis:
by the Eva analyzer: 0 errors 2 warnings
by the Frama-C kernel: 0 errors 0 warnings
---------------------------------------------------------------------------
0 alarms generated by the analysis.
---------------------------------------------------------------------------
Evaluation of the logical properties reached by the analysis:
Assertions 5 valid 0 unknown 0 invalid 5 total
Preconditions 22 valid 0 unknown 0 invalid 22 total
100% of the logical properties reached have been proven.
---------------------------------------------------------------------------
The warnings are:
[eva] validate_tlv.c:256: Warning:
this partitioning parameter cannot be evaluated safely on all states
[eva] validate_tlv.c:284: Warning:
this partitioning parameter cannot be evaluated safely on all states
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/uapi/linux/tlv_digest_list.h | 47 +++
security/integrity/digest_cache/Kconfig | 8 +
security/integrity/digest_cache/Makefile | 1 +
security/integrity/digest_cache/parsers/tlv.c | 341 ++++++++++++++++++
4 files changed, 397 insertions(+)
create mode 100644 include/uapi/linux/tlv_digest_list.h
create mode 100644 security/integrity/digest_cache/parsers/tlv.c
diff --git a/include/uapi/linux/tlv_digest_list.h b/include/uapi/linux/tlv_digest_list.h
new file mode 100644
index 000000000000..f2031cd70e64
--- /dev/null
+++ b/include/uapi/linux/tlv_digest_list.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Export definitions of the tlv digest list.
+ */
+
+#ifndef _UAPI_LINUX_TLV_DIGEST_LIST_H
+#define _UAPI_LINUX_TLV_DIGEST_LIST_H
+
+#include <linux/types.h>
+
+#define FOR_EACH_DIGEST_LIST_FIELD(DIGEST_LIST_FIELD) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_ALGO) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_NUM_ENTRIES) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_ENTRY) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_FIELD__LAST)
+
+#define FOR_EACH_DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_DIGEST) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_PATH) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD__LAST)
+
+#define GENERATE_ENUM(ENUM) ENUM,
+#define GENERATE_STRING(STRING) #STRING,
+
+/**
+ * enum digest_list_fields - Digest list fields
+ *
+ * Enumerates the digest list fields.
+ */
+enum digest_list_fields {
+ FOR_EACH_DIGEST_LIST_FIELD(GENERATE_ENUM)
+};
+
+/**
+ * enum digest_list_entry_fields - DIGEST_LIST_ENTRY fields
+ *
+ * Enumerates the DIGEST_LIST_ENTRY fields.
+ */
+enum digest_list_entry_fields {
+ FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_ENUM)
+};
+
+#endif /* _UAPI_LINUX_TLV_DIGEST_LIST_H */
diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig
index 65c07110911b..972bcf8bb765 100644
--- a/security/integrity/digest_cache/Kconfig
+++ b/security/integrity/digest_cache/Kconfig
@@ -33,3 +33,11 @@ config DIGEST_CACHE_HTABLE_DEPTH
A smaller number will increase the amount of hash table slots, and
make the search faster. A bigger number will decrease the number of
hash table slots, but make the search slower.
+
+config DIGEST_CACHE_TLV_PARSER
+ tristate "TLV digest list parser"
+ depends on INTEGRITY_DIGEST_CACHE
+ select TLV_PARSER
+ help
+ Add support for parsing TLV-formatted (Type Length Value)
+ digest list.
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index d68cae690241..3b42b20d1bc0 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -3,6 +3,7 @@
# Makefile for building the Integrity Digest Cache.
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
+obj-$(CONFIG_DIGEST_CACHE_TLV_PARSER) += parsers/tlv.o
digest_cache-y := main.o secfs.o htable.o parsers.o
diff --git a/security/integrity/digest_cache/parsers/tlv.c b/security/integrity/digest_cache/parsers/tlv.c
new file mode 100644
index 000000000000..31e407f0a43b
--- /dev/null
+++ b/security/integrity/digest_cache/parsers/tlv.c
@@ -0,0 +1,341 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Parse a tlv digest list.
+ */
+
+#define pr_fmt(fmt) "digest_cache TLV PARSER: "fmt
+#include <linux/module.h>
+#include <linux/tlv_parser.h>
+#include <linux/digest_cache.h>
+#include <uapi/linux/tlv_digest_list.h>
+
+#define kenter(FMT, ...) \
+ pr_debug("==> %s(" FMT ")\n", __func__, ##__VA_ARGS__)
+#define kleave(FMT, ...) \
+ pr_debug("<== %s()" FMT "\n", __func__, ##__VA_ARGS__)
+
+static const char *digest_list_fields_str[] = {
+ FOR_EACH_DIGEST_LIST_FIELD(GENERATE_STRING)
+};
+
+static const char *digest_list_entry_fields_str[] = {
+ FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_STRING)
+};
+
+struct tlv_callback_data {
+ struct digest_cache *digest_cache;
+ enum hash_algo algo;
+};
+
+/**
+ * parse_digest_list_entry_digest - Parse DIGEST_LIST_ENTRY_DIGEST field
+ * @tlv_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ENTRY_DIGEST field (file digest).
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_entry_digest(struct tlv_callback_data *tlv_data,
+ enum digest_list_entry_fields field,
+ const __u8 *field_data,
+ __u32 field_data_len)
+{
+ int ret;
+
+ kenter(",%u,%u", field, field_data_len);
+
+ if (tlv_data->algo == HASH_ALGO__LAST) {
+ pr_debug("Digest algo not set\n");
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ if (field_data_len != hash_digest_size[tlv_data->algo]) {
+ pr_debug("Unexpected data length %u, expected %d\n",
+ field_data_len, hash_digest_size[tlv_data->algo]);
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ ret = digest_cache_htable_add(tlv_data->digest_cache,
+ (__u8 *)field_data, tlv_data->algo);
+out:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * parse_digest_list_entry_path - Parse DIGEST_LIST_ENTRY_PATH field
+ * @tlv_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function handles the DIGEST_LIST_ENTRY_PATH field (file path). It
+ * currently does not parse the data.
+ *
+ * Return: Zero.
+ */
+static int parse_digest_list_entry_path(struct tlv_callback_data *tlv_data,
+ enum digest_list_entry_fields field,
+ const __u8 *field_data,
+ __u32 field_data_len)
+{
+ kenter(",%u,%u", field, field_data_len);
+
+ kleave(" = 0");
+ return 0;
+}
+
+/**
+ * digest_list_entry_callback - DIGEST_LIST_ENTRY callback
+ * @callback_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This callback handles the fields of DIGEST_LIST_ENTRY (nested) data, and
+ * calls the appropriate parser.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_list_entry_callback(void *callback_data, __u16 field,
+ const __u8 *field_data,
+ __u32 field_data_len)
+{
+ struct tlv_callback_data *tlv_data;
+ int ret;
+
+ tlv_data = (struct tlv_callback_data *)callback_data;
+
+ switch (field) {
+ case DIGEST_LIST_ENTRY_DIGEST:
+ ret = parse_digest_list_entry_digest(tlv_data, field,
+ field_data,
+ field_data_len);
+ break;
+ case DIGEST_LIST_ENTRY_PATH:
+ ret = parse_digest_list_entry_path(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ default:
+ pr_debug("Unhandled field %s\n",
+ digest_list_entry_fields_str[field]);
+ /* Just ignore non-relevant fields. */
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+/**
+ * parse_digest_list_algo - Parse DIGEST_LIST_ALGO field
+ * @tlv_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ALGO field (digest algorithm).
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_algo(struct tlv_callback_data *tlv_data,
+ enum digest_list_fields field,
+ const __u8 *field_data, __u32 field_data_len)
+{
+ __u16 algo;
+ int ret = 0;
+
+ kenter(",%u,%u", field, field_data_len);
+
+ if (field_data_len != sizeof(__u16)) {
+ pr_debug("Unexpected data length %u, expected %zu\n",
+ field_data_len, sizeof(__u16));
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ algo = __be16_to_cpu(*(__u16 *)field_data);
+
+ if (algo >= HASH_ALGO__LAST) {
+ pr_debug("Unexpected digest algo %u\n", algo);
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ tlv_data->algo = algo;
+
+ pr_debug("Digest algo: %s\n", hash_algo_name[algo]);
+out:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * parse_digest_list_num_entries - Parse DIGEST_LIST_NUM_ENTRIES field
+ * @tlv_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_NUM_ENTRIES field (digest list entries).
+ * This field must appear after DIGEST_LIST_ALGO.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_num_entries(struct tlv_callback_data *tlv_data,
+ enum digest_list_fields field,
+ const __u8 *field_data,
+ __u32 field_data_len)
+{
+ __u32 num_entries;
+ int ret;
+
+ kenter(",%u,%u", field, field_data_len);
+
+ if (field_data_len != sizeof(__u32)) {
+ pr_debug("Unexpected data length %u, expected %zu\n",
+ field_data_len, sizeof(__u32));
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ if (tlv_data->algo == HASH_ALGO__LAST) {
+ pr_debug("Digest algo not yet initialized\n");
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ num_entries = __be32_to_cpu(*(__u32 *)field_data);
+
+ ret = digest_cache_htable_init(tlv_data->digest_cache, num_entries,
+ tlv_data->algo);
+out:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * parse_digest_list_entry - Parse DIGEST_LIST_ENTRY field
+ * @tlv_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ENTRY field.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_entry(struct tlv_callback_data *tlv_data,
+ enum digest_list_fields field,
+ const __u8 *field_data, __u32 field_data_len)
+{
+ int ret;
+
+ kenter(",%u,%u", field, field_data_len);
+
+ ret = tlv_parse(digest_list_entry_callback, tlv_data, field_data,
+ field_data_len, digest_list_entry_fields_str,
+ DIGEST_LIST_ENTRY_FIELD__LAST);
+
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * digest_list_callback - Digest list callback
+ * @callback_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This callback handles the digest list fields, and calls the appropriate
+ * parser.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_list_callback(void *callback_data, __u16 field,
+ const __u8 *field_data, __u32 field_data_len)
+{
+ struct tlv_callback_data *tlv_data;
+ int ret;
+
+ tlv_data = (struct tlv_callback_data *)callback_data;
+
+ switch (field) {
+ case DIGEST_LIST_ALGO:
+ ret = parse_digest_list_algo(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ case DIGEST_LIST_NUM_ENTRIES:
+ ret = parse_digest_list_num_entries(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ case DIGEST_LIST_ENTRY:
+ ret = parse_digest_list_entry(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ default:
+ pr_debug("Unhandled field %s\n",
+ digest_list_fields_str[field]);
+ /* Just ignore non-relevant fields. */
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+/**
+ * digest_list_parse_tlv - Parse a tlv digest list
+ * @digest_cache: Digest cache
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function parses a tlv digest list.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_list_parse_tlv(struct digest_cache *digest_cache,
+ const __u8 *data, size_t data_len)
+{
+ struct tlv_callback_data tlv_data = {
+ .digest_cache = digest_cache,
+ .algo = HASH_ALGO__LAST,
+ };
+
+ return tlv_parse(digest_list_callback, &tlv_data, data, data_len,
+ digest_list_fields_str, DIGEST_LIST_FIELD__LAST);
+}
+
+static struct parser tlv_parser = {
+ .name = "tlv",
+ .owner = THIS_MODULE,
+ .func = digest_list_parse_tlv,
+};
+
+static int __init tlv_parser_init(void)
+{
+ return digest_cache_register_parser(&tlv_parser);
+}
+
+static void __exit tlv_parser_exit(void)
+{
+ digest_cache_unregister_parser(&tlv_parser);
+}
+
+module_init(tlv_parser_init);
+module_exit(tlv_parser_exit);
+
+MODULE_AUTHOR("Roberto Sassu");
+MODULE_DESCRIPTION("TLV digest list parser");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0.0");
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 09/15] digest_cache: Populate the digest cache from a digest list
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Introduce digest_cache_populate() to populate the digest cache from a
digest list. Call it from digest_cache_init() if the inode is a regular
file.
It opens the file, marks it for internal use with
digest_cache_to_file_sec(), and then schedules a work to read the content
(with new file type READING_DIGEST_LIST). Scheduling a work solves the
problem of kernel_read_file() returning -EINTR.
Once the work is done, this function calls digest_cache_strip_modsig() to
strip a module-style appended signature, if present, and finally calls
digest_cache_parse_digest_list() to parse the data.
Failing to populate a digest cache causes it to be marked as invalid and to
not be returned by digest_cache_init(). Dig_owner however is kept, to
avoid an excessive number of retries, which would probably not succeed
either.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/linux/kernel_read_file.h | 1 +
security/integrity/digest_cache/Makefile | 2 +-
security/integrity/digest_cache/internal.h | 25 ++++++
security/integrity/digest_cache/main.c | 16 ++++
security/integrity/digest_cache/modsig.c | 66 +++++++++++++++
security/integrity/digest_cache/populate.c | 97 ++++++++++++++++++++++
6 files changed, 206 insertions(+), 1 deletion(-)
create mode 100644 security/integrity/digest_cache/modsig.c
create mode 100644 security/integrity/digest_cache/populate.c
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 90451e2e12bd..85f602e49e2f 100644
--- a/include/linux/kernel_read_file.h
+++ b/include/linux/kernel_read_file.h
@@ -14,6 +14,7 @@
id(KEXEC_INITRAMFS, kexec-initramfs) \
id(POLICY, security-policy) \
id(X509_CERTIFICATE, x509-certificate) \
+ id(DIGEST_LIST, digest-list) \
id(MAX_ID, )
#define __fid_enumify(ENUM, dummy) READING_ ## ENUM,
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index 3b42b20d1bc0..3b81edea065b 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -5,6 +5,6 @@
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
obj-$(CONFIG_DIGEST_CACHE_TLV_PARSER) += parsers/tlv.o
-digest_cache-y := main.o secfs.o htable.o parsers.o
+digest_cache-y := main.o secfs.o htable.o parsers.o populate.o modsig.o
CFLAGS_parsers.o += -DPARSERS_DIR=\"$(MODLIB)/kernel/security/integrity/digest_cache/parsers\"
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index e178549f9ff9..2171ea8423ff 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -18,6 +18,23 @@
#define INIT_STARTED 1 /* Digest cache init started. */
#define INVALID 2 /* Digest cache marked as invalid. */
+/**
+ * struct read_work - Structure to schedule reading a digest list
+ * @work: Work structure
+ * @file: File descriptor of the digest list to read
+ * @data: Digest list data (updated)
+ * @ret: Return value from kernel_read_file() (updated)
+ *
+ * This structure contains the necessary information to schedule reading a
+ * digest list.
+ */
+struct read_work {
+ struct work_struct work;
+ struct file *file;
+ void *data;
+ int ret;
+};
+
/**
* struct digest_cache_entry - Entry of a digest cache hash table
* @hnext: Pointer to the next element in the collision list
@@ -166,4 +183,12 @@ int digest_cache_parse_digest_list(struct dentry *dentry,
struct digest_cache *digest_cache,
char *path_str, void *data, size_t data_len);
+/* populate.c */
+int digest_cache_populate(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ struct path *digest_list_path);
+
+/* modsig.c */
+size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index ebc5dc09a62b..ad0f34c7ef9b 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -267,6 +267,9 @@ struct digest_cache *digest_cache_init(struct dentry *dentry,
struct path *digest_list_path,
struct digest_cache *digest_cache)
{
+ struct inode *inode;
+ int ret;
+
/* Wait for digest cache initialization. */
if (!digest_list_path->dentry ||
test_and_set_bit(INIT_STARTED, &digest_cache->flags)) {
@@ -275,6 +278,19 @@ struct digest_cache *digest_cache_init(struct dentry *dentry,
goto out;
}
+ inode = d_backing_inode(digest_list_path->dentry);
+
+ if (S_ISREG(inode->i_mode)) {
+ ret = digest_cache_populate(dentry, digest_cache,
+ digest_list_path);
+ if (ret < 0) {
+ pr_debug("Failed to populate digest cache %s ret: %d (keep digest cache)\n",
+ digest_cache->path_str, ret);
+ /* Prevent usage of partially-populated digest cache. */
+ set_bit(INVALID, &digest_cache->flags);
+ }
+ }
+
/* Notify initialization complete. */
clear_and_wake_up_bit(INIT_IN_PROGRESS, &digest_cache->flags);
out:
diff --git a/security/integrity/digest_cache/modsig.c b/security/integrity/digest_cache/modsig.c
new file mode 100644
index 000000000000..fa512c43a556
--- /dev/null
+++ b/security/integrity/digest_cache/modsig.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2019 IBM Corporation
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Strip module-style appended signatures.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include <linux/module.h>
+#include <linux/module_signature.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_strip_modsig - Strip module-style appended sig from digest list
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function strips the module-style appended signature from a digest list,
+ * if present.
+ *
+ * Return: Size of stripped data on success, original size otherwise.
+ */
+size_t digest_cache_strip_modsig(__u8 *data, size_t data_len)
+{
+ const size_t marker_len = strlen(MODULE_SIG_STRING);
+ const struct module_signature *sig;
+ size_t parsed_data_len = data_len;
+ size_t sig_len;
+ const void *p;
+
+ /* From ima_modsig.c */
+ if (data_len <= marker_len + sizeof(*sig))
+ return data_len;
+
+ p = data + parsed_data_len - marker_len;
+ if (memcmp(p, MODULE_SIG_STRING, marker_len))
+ return data_len;
+
+ parsed_data_len -= marker_len;
+ sig = (const struct module_signature *)(p - sizeof(*sig));
+
+ /* From module_signature.c */
+ if (be32_to_cpu(sig->sig_len) >= parsed_data_len - sizeof(*sig))
+ return data_len;
+
+ /* Unlike for module signatures, accept all signature types. */
+ if (sig->algo != 0 ||
+ sig->hash != 0 ||
+ sig->signer_len != 0 ||
+ sig->key_id_len != 0 ||
+ sig->__pad[0] != 0 ||
+ sig->__pad[1] != 0 ||
+ sig->__pad[2] != 0) {
+ pr_debug("Signature info has unexpected non-zero params\n");
+ return data_len;
+ }
+
+ sig_len = be32_to_cpu(sig->sig_len);
+ parsed_data_len -= sig_len + sizeof(*sig);
+ return parsed_data_len;
+}
diff --git a/security/integrity/digest_cache/populate.c b/security/integrity/digest_cache/populate.c
new file mode 100644
index 000000000000..54f7f95f5794
--- /dev/null
+++ b/security/integrity/digest_cache/populate.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the code to populate a digest cache.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include <linux/init_task.h>
+#include <linux/vmalloc.h>
+#include <linux/kernel_read_file.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_read_digest_list - Read a digest list
+ * @work: Work structure
+ *
+ * This function is invoked by schedule_work() to read a digest list.
+ *
+ * It does not return a value, but stores the result in the passed structure.
+ */
+static void digest_cache_read_digest_list(struct work_struct *work)
+{
+ struct read_work *w = container_of(work, struct read_work, work);
+
+ w->ret = kernel_read_file(w->file, 0, &w->data, INT_MAX, NULL,
+ READING_DIGEST_LIST);
+}
+
+/**
+ * digest_cache_populate - Populate a digest cache from a digest list
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ * @digest_cache: Digest cache
+ * @digest_list_path: Path structure of the digest list
+ *
+ * This function opens the digest list for reading it. Then, it schedules a
+ * work to read the digest list and, once the work is done, it calls
+ * digest_cache_strip_modsig() to strip a module-style appended signature and
+ * digest_cache_parse_digest_list() for extracting and adding digests to the
+ * digest cache.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_populate(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ struct path *digest_list_path)
+{
+ struct file *file;
+ void *data;
+ size_t data_len;
+ struct read_work w;
+ int ret;
+
+ file = kernel_file_open(digest_list_path, O_RDONLY, &init_cred);
+ if (IS_ERR(file)) {
+ pr_debug("Unable to open digest list %s, ret: %ld\n",
+ digest_cache->path_str, PTR_ERR(file));
+ return PTR_ERR(file);
+ }
+
+ /* Mark the file descriptor as ours. */
+ digest_cache_to_file_sec(file, digest_cache);
+
+ w.data = NULL;
+ w.file = file;
+ INIT_WORK_ONSTACK(&w.work, digest_cache_read_digest_list);
+
+ schedule_work(&w.work);
+ flush_work(&w.work);
+ destroy_work_on_stack(&w.work);
+ fput(file);
+
+ ret = w.ret;
+ data = w.data;
+
+ if (ret < 0) {
+ pr_debug("Unable to read digest list %s, ret: %d\n",
+ digest_cache->path_str, ret);
+ return ret;
+ }
+
+ data_len = digest_cache_strip_modsig(data, ret);
+
+ /* Digest list parsers initialize the hash table and add the digests. */
+ ret = digest_cache_parse_digest_list(dentry, digest_cache,
+ digest_cache->path_str, data,
+ data_len);
+ if (ret < 0)
+ pr_debug("Error parsing digest list %s, ret: %d\n",
+ digest_cache->path_str, ret);
+
+ vfree(data);
+ return ret;
+}
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 10/15] digest_cache: Add management of verification data
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
The Integrity Digest Cache can support other LSMs in their decisions of
granting access to file data and metadata.
However, the information alone about whether a digest was found in a digest
cache might not be sufficient, because for example those LSMs wouldn't know
about the integrity of the digest list digests were extracted from.
Introduce digest_cache_verif_set() to let the same LSMs (or a chosen
integrity provider) evaluate the digest list being read during the creation
of the digest cache, by implementing the kernel_post_read_file LSM hook,
and let them attach their verification data to that digest cache.
digest_cache_verif_set() receives as argument a file descriptor and calls
digest_cache_from_file_sec() to obtain back the digest cache being created
from that file descriptor. The digest cache being created was associated to
the file descriptor by digest_cache_populate(), before reading the digest
list from the kernel, by calling digest_cache_to_file_sec().
Multiple providers are supported, in the event there are multiple
integrity LSMs active. Each provider should also provide a unique verifier
ID as an argument to digest_cache_verif_set(), so that verification data
can be distinguished. Concurrent set are protected by the verif_data_lock
spinlock.
A caller of digest_cache_get() can retrieve back the verification data by
calling digest_cache_verif_get() and passing a digest cache pointer and the
desired verifier ID.
Since directory digest caches are not populated themselves, LSMs have to do
a lookup first to get the digest cache containing the digest, and pass the
returned digest cache reference to digest_cache_verif_get().
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/linux/digest_cache.h | 17 +++
security/integrity/digest_cache/Makefile | 3 +-
security/integrity/digest_cache/internal.h | 22 ++++
security/integrity/digest_cache/main.c | 3 +
security/integrity/digest_cache/verif.c | 131 +++++++++++++++++++++
5 files changed, 175 insertions(+), 1 deletion(-)
create mode 100644 security/integrity/digest_cache/verif.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index a9d731990b7c..d2483fe588be 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -47,6 +47,10 @@ bool digest_cache_opened_fd(struct file *file);
struct digest_cache *digest_cache_lookup(struct dentry *dentry,
struct digest_cache *digest_cache,
u8 *digest, enum hash_algo algo);
+int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
+ size_t size);
+void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id);
/* Parser API */
int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
@@ -81,6 +85,19 @@ digest_cache_lookup(struct dentry *dentry, struct digest_cache *digest_cache,
return NULL;
}
+static inline int digest_cache_verif_set(struct file *file,
+ const char *verif_id, void *data,
+ size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id)
+{
+ return NULL;
+}
+
static inline int digest_cache_htable_init(struct digest_cache *digest_cache,
u64 num_digests, enum hash_algo algo)
{
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index 3b81edea065b..2a0f2500e227 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
obj-$(CONFIG_DIGEST_CACHE_TLV_PARSER) += parsers/tlv.o
-digest_cache-y := main.o secfs.o htable.o parsers.o populate.o modsig.o
+digest_cache-y := main.o secfs.o htable.o parsers.o populate.o modsig.o \
+ verif.o
CFLAGS_parsers.o += -DPARSERS_DIR=\"$(MODLIB)/kernel/security/integrity/digest_cache/parsers\"
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index 2171ea8423ff..c64e91b75a47 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -18,6 +18,21 @@
#define INIT_STARTED 1 /* Digest cache init started. */
#define INVALID 2 /* Digest cache marked as invalid. */
+/**
+ * struct digest_cache_verif
+ * @list: Linked list
+ * @verif_id: Identifier of who verified the digest list
+ * @data: Opaque data set by the digest list verifier
+ *
+ * This structure contains opaque data containing the result of verification
+ * of the digest list by a verifier.
+ */
+struct digest_cache_verif {
+ struct list_head list;
+ char *verif_id;
+ void *data;
+};
+
/**
* struct read_work - Structure to schedule reading a digest list
* @work: Work structure
@@ -72,6 +87,8 @@ struct htable {
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
+ * @verif_data: Verification data regarding the digest list
+ * @verif_data_lock: Protects verification data modifications
*
* This structure represents a cache of digests extracted from a digest list.
*/
@@ -80,6 +97,8 @@ struct digest_cache {
atomic_t ref_count;
char *path_str;
unsigned long flags;
+ struct list_head verif_data;
+ spinlock_t verif_data_lock;
};
/**
@@ -191,4 +210,7 @@ int digest_cache_populate(struct dentry *dentry,
/* modsig.c */
size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
+/* verif.c */
+void digest_cache_verif_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index ad0f34c7ef9b..11a0445592f0 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -52,6 +52,8 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
atomic_set(&digest_cache->ref_count, 1);
digest_cache->flags = 0UL;
INIT_LIST_HEAD(&digest_cache->htables);
+ INIT_LIST_HEAD(&digest_cache->verif_data);
+ spin_lock_init(&digest_cache->verif_data_lock);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -68,6 +70,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
static void digest_cache_free(struct digest_cache *digest_cache)
{
digest_cache_htable_free(digest_cache);
+ digest_cache_verif_free(digest_cache);
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
diff --git a/security/integrity/digest_cache/verif.c b/security/integrity/digest_cache/verif.c
new file mode 100644
index 000000000000..03ebf0de764b
--- /dev/null
+++ b/security/integrity/digest_cache/verif.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Manage verification data regarding digest lists.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include "internal.h"
+
+/**
+ * free_verif - Free a digest_cache_verif structure
+ * @verif: digest_cache_verif structure
+ *
+ * Free the space allocated for a digest_cache_verif structure.
+ */
+static void free_verif(struct digest_cache_verif *verif)
+{
+ kfree(verif->data);
+ kfree(verif->verif_id);
+ kfree(verif);
+}
+
+/**
+ * digest_cache_verif_set - Set digest cache verification data
+ * @file: File descriptor of the digest list being read to populate digest cache
+ * @verif_id: Verifier ID
+ * @data: Verification data (opaque)
+ * @size: Size of @data
+ *
+ * This function lets a verifier supply verification data about a digest list
+ * being read to populate the digest cache. Verifier ID must be unique.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
+ size_t size)
+{
+ struct digest_cache *digest_cache = digest_cache_from_file_sec(file);
+ struct digest_cache_verif *new_verif, *verif;
+ /* All allocations done by kprobe must be atomic (non-sleepable). */
+ gfp_t flags = !strncmp(verif_id, "kprobe", 6) ? GFP_ATOMIC : GFP_KERNEL;
+ int ret = 0;
+
+ /*
+ * Zero the data, so that we can always call free_verif() to free a
+ * partially filled structure (if a pointer is NULL, will not be freed).
+ */
+ new_verif = kzalloc(sizeof(*new_verif), flags);
+ if (!new_verif)
+ return -ENOMEM;
+
+ new_verif->verif_id = kstrdup(verif_id, flags);
+ if (!new_verif->verif_id) {
+ free_verif(new_verif);
+ return -ENOMEM;
+ }
+
+ new_verif->data = kmemdup(data, size, flags);
+ if (!new_verif->data) {
+ free_verif(new_verif);
+ return -ENOMEM;
+ }
+
+ spin_lock(&digest_cache->verif_data_lock);
+ list_for_each_entry(verif, &digest_cache->verif_data, list) {
+ if (!strcmp(verif->verif_id, verif_id)) {
+ ret = -EEXIST;
+ goto out;
+ }
+ }
+
+ list_add_tail_rcu(&new_verif->list, &digest_cache->verif_data);
+out:
+ spin_unlock(&digest_cache->verif_data_lock);
+
+ if (ret < 0)
+ free_verif(new_verif);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(digest_cache_verif_set);
+
+/**
+ * digest_cache_verif_get - Get digest cache verification data
+ * @digest_cache: Digest cache
+ * @verif_id: Verifier ID
+ *
+ * This function returns the verification data previously set by a verifier
+ * with digest_cache_verif_set().
+ *
+ * Return: Verification data if found, NULL otherwise.
+ */
+void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id)
+{
+ struct digest_cache_verif *verif;
+ void *verif_data = NULL;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(verif, &digest_cache->verif_data, list) {
+ if (!strcmp(verif->verif_id, verif_id)) {
+ verif_data = verif->data;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return verif_data;
+}
+EXPORT_SYMBOL_GPL(digest_cache_verif_get);
+
+/**
+ * digest_cache_verif_free - Free all digest_cache_verif structures
+ * @digest_cache: Digest cache
+ *
+ * This function frees the space allocated for all digest_cache_verif
+ * structures in the digest cache.
+ */
+void digest_cache_verif_free(struct digest_cache *digest_cache)
+{
+ struct digest_cache_verif *p, *q;
+
+ /* No need to lock, called when nobody else has a digest cache ref. */
+ list_for_each_entry_safe(p, q, &digest_cache->verif_data, list) {
+ list_del(&p->list);
+ free_verif(p);
+ }
+}
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 11/15] digest_cache: Add support for directories
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
In the environments where xattrs are not available (e.g. in the initial ram
disk), the Integrity Digest Cache cannot precisely determine which digest
list in a directory contains the desired reference digest. However,
although slower, it would be desirable to search the digest in all digest
lists of that directory.
This done in three steps. First, a directory digest cache is created like
the other digest caches. The only differences are that this digest cache
has the IS_DIR bit set, to distinguish it from those created from regular
files and, consequently, that it stores a list of directory entries file
names instead of hash tables for digests.
Second, the directory digest cache is populated with current directory
entries, by calling digest_cache_dir_add_entries().
Finally, digest_cache_dir_lookup_digest() is called with the directory
digest cache passed as argument, to iteratively search on each digest cache
for each directory entry.
The function first calls digest_cache_dir_create() to create/obtain the
current directory digest cache for the directory. If the latter returns
a different one than the one passed, digest_cache_dir_lookup_digest()
returns ERR_PTR(-EAGAIN) to let the caller of digest_cache_lookup() know
that the directory digest cache changed, and make the caller perform
another digest_cache_get() to get a fresh directory digest cache.
If the passed and the current directory digest caches match,
digest_cache_dir_lookup_digest() starts the lookup and iteratively searches
the passed digest in each directory entry. If there is no digest cache
associated to the current directory entry, digest_cache_dir_lookup_digest()
creates/obtains one by calling digest_cache_create(). It also keeps a
digest cache reference, so that it is available for next searches. The
iteration stops when the digest is found.
Finally, digest_cache_dir_free() releases the digest cache references
stored in the list of directory entries, and frees the list itself.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/digest_cache/Makefile | 2 +-
security/integrity/digest_cache/dir.c | 263 +++++++++++++++++++++
security/integrity/digest_cache/htable.c | 7 +-
security/integrity/digest_cache/internal.h | 44 ++++
security/integrity/digest_cache/main.c | 13 +
5 files changed, 327 insertions(+), 2 deletions(-)
create mode 100644 security/integrity/digest_cache/dir.c
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index 2a0f2500e227..d07ac2483504 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -6,6 +6,6 @@ obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
obj-$(CONFIG_DIGEST_CACHE_TLV_PARSER) += parsers/tlv.o
digest_cache-y := main.o secfs.o htable.o parsers.o populate.o modsig.o \
- verif.o
+ verif.o dir.o
CFLAGS_parsers.o += -DPARSERS_DIR=\"$(MODLIB)/kernel/security/integrity/digest_cache/parsers\"
diff --git a/security/integrity/digest_cache/dir.c b/security/integrity/digest_cache/dir.c
new file mode 100644
index 000000000000..8f9e550c365f
--- /dev/null
+++ b/security/integrity/digest_cache/dir.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Manage digest caches from directories.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include <linux/init_task.h>
+#include <linux/namei.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_dir_iter - Digest cache directory iterator
+ * @__ctx: iterate_dir() context
+ * @name: Name of file in the accessed directory
+ * @namelen: String length of @name
+ * @offset: Current position in the directory stream (see man readdir)
+ * @ino: Inode number
+ * @d_type: File type
+ *
+ * This function stores the names of the files in the containing directory in
+ * a linked list. If they are in the format
+ * <seq num>-<digest list format>-<digest list name>, this function orders them
+ * by seq num, so that digest lists are processed in the desired order.
+ * Otherwise, if <seq num>- is not included, it adds the name at the end of
+ * the list.
+ *
+ * Return: True to continue processing, false to stop.
+ */
+static bool digest_cache_dir_iter(struct dir_context *__ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct readdir_callback *ctx = container_of(__ctx, typeof(*ctx), ctx);
+ struct dir_entry *new_entry, *p;
+ unsigned int seq_num;
+ char *separator;
+ int ret;
+
+ if (!strcmp(name, ".") || !strcmp(name, ".."))
+ return true;
+
+ if (d_type != DT_REG)
+ return true;
+
+ new_entry = kmalloc(sizeof(*new_entry) + namelen + 1, GFP_KERNEL);
+ if (!new_entry)
+ return false;
+
+ memcpy(new_entry->name, name, namelen);
+ new_entry->name[namelen] = '\0';
+ new_entry->seq_num = UINT_MAX;
+ new_entry->digest_cache = NULL;
+ mutex_init(&new_entry->digest_cache_mutex);
+
+ if (new_entry->name[0] < '0' || new_entry->name[0] > '9')
+ goto out;
+
+ separator = strchr(new_entry->name, '-');
+ if (!separator)
+ goto out;
+
+ *separator = '\0';
+ ret = kstrtouint(new_entry->name, 10, &seq_num);
+ *separator = '-';
+ if (ret < 0)
+ goto out;
+
+ new_entry->seq_num = seq_num;
+
+ list_for_each_entry(p, ctx->head, list) {
+ if (seq_num <= p->seq_num) {
+ list_add(&new_entry->list, p->list.prev);
+ pr_debug("Added %s before %s in dir list\n",
+ new_entry->name, p->name);
+ return true;
+ }
+ }
+out:
+ list_add_tail(&new_entry->list, ctx->head);
+ pr_debug("Added %s to tail of dir list\n", new_entry->name);
+ return true;
+}
+
+/**
+ * digest_cache_dir_add_entries - Add dir entries to a dir digest cache
+ * @digest_cache: Dir digest cache
+ * @digest_list_path: Path structure of the digest list directory
+ *
+ * This function iterates over the entries of a directory, and creates a linked
+ * list of file names from that directory.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_dir_add_entries(struct digest_cache *digest_cache,
+ struct path *digest_list_path)
+{
+ struct file *dir_file;
+ struct readdir_callback buf = {
+ .ctx.actor = digest_cache_dir_iter,
+ .ctx.pos = 0,
+ .head = &digest_cache->dir_entries,
+ };
+ int ret;
+
+ dir_file = kernel_file_open(digest_list_path, O_RDONLY, &init_cred);
+ if (IS_ERR(dir_file)) {
+ pr_debug("Cannot access %s, ret: %ld\n", digest_cache->path_str,
+ PTR_ERR(dir_file));
+ return PTR_ERR(dir_file);
+ }
+
+ ret = iterate_dir(dir_file, &buf.ctx);
+ if (ret < 0)
+ pr_debug("Failed to iterate directory %s\n",
+ digest_cache->path_str);
+
+ fput(dir_file);
+ return ret;
+}
+
+/**
+ * digest_cache_dir_create - Create and initialize a directory digest cache
+ * @dentry: Dentry of the file whose digest is looked up
+ * @dir_path: Path structure of the digest list directory (updated)
+ * @path_str: Path string of the digest list directory
+ *
+ * This function creates and initializes (or obtains if it already exists) a
+ * directory digest cache. It updates the path that digest cache was
+ * created/obtained from, so that the caller can use it to perform lookup
+ * operations.
+ *
+ * Return: A directory digest cache on success, NULL otherwise.
+ */
+static struct digest_cache *digest_cache_dir_create(struct dentry *dentry,
+ struct path *dir_path,
+ char *path_str)
+{
+ struct digest_cache *digest_cache;
+ struct path _dir_path;
+ int ret;
+
+ ret = kern_path(path_str, 0, &_dir_path);
+ if (ret < 0) {
+ pr_debug("Cannot find path %s\n", path_str);
+ return NULL;
+ }
+
+ digest_cache = digest_cache_create(dentry, &_dir_path, dir_path,
+ path_str, "");
+ if (digest_cache)
+ digest_cache = digest_cache_init(dentry, dir_path,
+ digest_cache);
+
+ path_put(&_dir_path);
+ return digest_cache;
+}
+
+/**
+ * digest_cache_dir_lookup_digest - Lookup a digest
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_cache: Dir digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function iterates over the linked list created by
+ * digest_cache_dir_add_entries() and looks up the digest in the digest cache
+ * of each entry.
+ *
+ * Return: A digest cache reference if the digest is found, NULL if not, an
+ * error pointer if dir digest cache changed since last get.
+ */
+struct digest_cache *
+digest_cache_dir_lookup_digest(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct dir_entry *dir_entry;
+ struct digest_cache *dir_cache, *cache, *found = NULL;
+ struct path dir_path = { .dentry = NULL, .mnt = NULL };
+ struct path digest_list_path;
+ int ret;
+
+ /* Try to reacquire the dir digest cache, and check if changed. */
+ dir_cache = digest_cache_dir_create(dentry, &dir_path,
+ digest_cache->path_str);
+ if (dir_cache != digest_cache) {
+ if (dir_cache)
+ found = ERR_PTR(-EAGAIN);
+
+ goto out;
+ }
+
+ list_for_each_entry(dir_entry, &dir_cache->dir_entries, list) {
+ mutex_lock(&dir_entry->digest_cache_mutex);
+ if (!dir_entry->digest_cache) {
+ digest_list_path.dentry = NULL;
+ digest_list_path.mnt = NULL;
+
+ cache = digest_cache_create(dentry, &dir_path,
+ &digest_list_path,
+ dir_cache->path_str,
+ dir_entry->name);
+ if (cache)
+ cache = digest_cache_init(dentry,
+ &digest_list_path,
+ cache);
+
+ if (digest_list_path.dentry)
+ path_put(&digest_list_path);
+
+ /* Ignore digest caches that cannot be instantiated. */
+ if (!cache) {
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+ continue;
+ }
+
+ /* Consume extra ref. from digest_cache_create(). */
+ dir_entry->digest_cache = cache;
+ }
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+
+ ret = digest_cache_htable_lookup(dentry,
+ dir_entry->digest_cache,
+ digest, algo);
+ if (!ret) {
+ found = digest_cache_ref(dir_entry->digest_cache);
+ break;
+ }
+ }
+out:
+ if (dir_cache)
+ digest_cache_put(dir_cache);
+ if (dir_path.dentry)
+ path_put(&dir_path);
+
+ return found;
+}
+
+/**
+ * digest_cache_dir_free - Free the stored file list and put digest caches
+ * @digest_cache: Dir digest cache
+ *
+ * This function frees the file list created by digest_cache_dir_add_entries(),
+ * and puts the digest cache of each directory entry, if a reference exists.
+ */
+void digest_cache_dir_free(struct digest_cache *digest_cache)
+{
+ struct dir_entry *p, *q;
+
+ list_for_each_entry_safe(p, q, &digest_cache->dir_entries, list) {
+ if (p->digest_cache)
+ digest_cache_put(p->digest_cache);
+
+ list_del(&p->list);
+ mutex_destroy(&p->digest_cache_mutex);
+ kfree(p);
+ }
+}
diff --git a/security/integrity/digest_cache/htable.c b/security/integrity/digest_cache/htable.c
index 8aa6d50a0cb5..a01e24d7f198 100644
--- a/security/integrity/digest_cache/htable.c
+++ b/security/integrity/digest_cache/htable.c
@@ -202,7 +202,8 @@ EXPORT_SYMBOL_GPL(digest_cache_htable_lookup);
* This function calls digest_cache_htable_lookup() to search a digest in the
* passed digest cache, obtained with digest_cache_get().
*
- * Return: A digest cache reference the digest is found, NULL if not.
+ * Return: A digest cache reference if the digest is found, NULL if not, an
+ * error pointer if dir digest cache changed since last get.
*/
struct digest_cache *digest_cache_lookup(struct dentry *dentry,
struct digest_cache *digest_cache,
@@ -210,6 +211,10 @@ struct digest_cache *digest_cache_lookup(struct dentry *dentry,
{
int ret;
+ if (test_bit(IS_DIR, &digest_cache->flags))
+ return digest_cache_dir_lookup_digest(dentry, digest_cache,
+ digest, algo);
+
ret = digest_cache_htable_lookup(dentry, digest_cache, digest, algo);
if (ret < 0)
return NULL;
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index c64e91b75a47..f849afe5e47b 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -17,6 +17,39 @@
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
#define INIT_STARTED 1 /* Digest cache init started. */
#define INVALID 2 /* Digest cache marked as invalid. */
+#define IS_DIR 3 /* Digest cache created from dir. */
+
+/**
+ * struct readdir_callback - Structure to store information for dir iteration
+ * @ctx: Context structure
+ * @head: Head of linked list of directory entries
+ *
+ * This structure stores information to be passed from the iterate_dir() caller
+ * to the directory iterator.
+ */
+struct readdir_callback {
+ struct dir_context ctx;
+ struct list_head *head;
+};
+
+/**
+ * struct dir_entry - Directory entry
+ * @list: Linked list of directory entries
+ * @digest_cache: Digest cache associated to the directory entry
+ * @digest_cache_mutex: Protects @digest_cache
+ * @seq_num: Sequence number of the directory entry from file name
+ * @name: File name of the directory entry
+ *
+ * This structure represents a directory entry with a digest cache created
+ * from that entry.
+ */
+struct dir_entry {
+ struct list_head list;
+ struct digest_cache *digest_cache;
+ struct mutex digest_cache_mutex;
+ unsigned int seq_num;
+ char name[];
+};
/**
* struct digest_cache_verif
@@ -84,6 +117,7 @@ struct htable {
/**
* struct digest_cache - Digest cache
* @htables: Hash tables (one per algorithm)
+ * @dir_entries: List of files in a directory and the digest cache
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
@@ -94,6 +128,7 @@ struct htable {
*/
struct digest_cache {
struct list_head htables;
+ struct list_head dir_entries;
atomic_t ref_count;
char *path_str;
unsigned long flags;
@@ -213,4 +248,13 @@ size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
/* verif.c */
void digest_cache_verif_free(struct digest_cache *digest_cache);
+/* dir.c */
+int digest_cache_dir_add_entries(struct digest_cache *digest_cache,
+ struct path *digest_cache_path);
+struct digest_cache *
+digest_cache_dir_lookup_digest(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
+void digest_cache_dir_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index 11a0445592f0..9df819c323c7 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -54,6 +54,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
INIT_LIST_HEAD(&digest_cache->htables);
INIT_LIST_HEAD(&digest_cache->verif_data);
spin_lock_init(&digest_cache->verif_data_lock);
+ INIT_LIST_HEAD(&digest_cache->dir_entries);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -71,6 +72,7 @@ static void digest_cache_free(struct digest_cache *digest_cache)
{
digest_cache_htable_free(digest_cache);
digest_cache_verif_free(digest_cache);
+ digest_cache_dir_free(digest_cache);
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
@@ -292,6 +294,17 @@ struct digest_cache *digest_cache_init(struct dentry *dentry,
/* Prevent usage of partially-populated digest cache. */
set_bit(INVALID, &digest_cache->flags);
}
+ } else if (S_ISDIR(inode->i_mode)) {
+ set_bit(IS_DIR, &digest_cache->flags);
+
+ ret = digest_cache_dir_add_entries(digest_cache,
+ digest_list_path);
+ if (ret < 0) {
+ pr_debug("Failed to add dir entries to dir digest cache, ret: %d (keep digest cache)\n",
+ ret);
+ /* Prevent usage of partially-populated digest cache. */
+ set_bit(INVALID, &digest_cache->flags);
+ }
}
/* Notify initialization complete. */
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 12/15] digest cache: Prefetch digest lists if requested
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
A desirable goal when doing integrity measurements is that they are done
always in the same order across boots, so that the resulting PCR value
becomes predictable and suitable for sealing policies. However, due to
parallel execution of system services at boot, a deterministic order of
measurements is difficult to achieve.
The Integrity Digest Cache is not exempted from this issue. If callers
of digest_cache_get() pass file descriptors of inodes in an unpredictable
order, this very likely will result in reading digest lists in an
unpredictable order too.
Overcome this issue by introducing digest_cache_dir_prefetch() and
digest_cache_dir_lookup_filename(), to sequentially search the digest list
the digest cache will be populated from in the parent directory, instead
of directly accessing it from the full path.
If during the file name search there is no match, read the digest list to
trigger its measurement (if an appropriate policy exists). If there is a
match, attempt to create and initialize the digest cache from the found
file name.
This ensures that measurements are always done in the same order as the
file names stored in the digest cache of the parent directory, regardless
of which digest list was requested. However, the PCR still changes every
time a not yet read digest list is requested. In any case, the possible PCR
values are more manageable than in the unpredictable file access case, at
most the number of digest lists. Of course, PCR values further change when
digest lists are added/removed to/from the parent directory, or if the
parent directory itself is modified through securityfs.
The prefetching mechanism has been designed to be more like a aid to get
predictable measurements, and does not defend against path change attacks.
It assumes that the path does not change between retrieving the digest
cache associated to an inode and prefetching (i.e. the prefetching
mechanism gets the same digest cache). If the path changed, and the
prefetching mechanism retrieved a different digest cache,
digest_cache_get() still continues to use the one it retrieved, and will
ignore the prefetched one.
Prefetching is enabled by setting the newly introduced
'security.dig_prefetch' xattr to '1'. digest_cache_new() and
digest_cache_dir_create() call digest_cache_prefetch_requested() to check
it. They pass the check result to digest_cache_create(), which in turn sets
the DIR_PREFETCH and FILE_PREFETCH bit respectively in the parent directory
and regular file digest cache.
On subsequent calls to digest_cache_prefetch_requested(), the latter can
just test for DIR_PREFETCH bit (faster).
digest_cache_get(), after digest cache creation, checks if the digest cache
has the FILE_PREFETCH bit set and, if yes, calls
digest_cache_dir_prefetch() to do prefetching. For just reading digest
lists, digest_cache_dir_prefetch() asks digest_cache_create() to create
special digest caches with the FILE_READ bit set, so that
digest_cache_populate() does not attempt to extract digests. The special
digest caches also are not attached to the corresponding inode.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
include/uapi/linux/xattr.h | 3 +
security/integrity/digest_cache/dir.c | 135 ++++++++++++++++++++-
security/integrity/digest_cache/internal.h | 12 +-
security/integrity/digest_cache/main.c | 96 ++++++++++++++-
security/integrity/digest_cache/populate.c | 9 +-
security/integrity/digest_cache/verif.c | 4 +
6 files changed, 251 insertions(+), 8 deletions(-)
diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h
index 8a58cf4bce65..8af33d38d9e8 100644
--- a/include/uapi/linux/xattr.h
+++ b/include/uapi/linux/xattr.h
@@ -57,6 +57,9 @@
#define XATTR_DIGEST_LIST_SUFFIX "digest_list"
#define XATTR_NAME_DIGEST_LIST XATTR_SECURITY_PREFIX XATTR_DIGEST_LIST_SUFFIX
+#define XATTR_DIG_PREFETCH_SUFFIX "dig_prefetch"
+#define XATTR_NAME_DIG_PREFETCH XATTR_SECURITY_PREFIX XATTR_DIG_PREFETCH_SUFFIX
+
#define XATTR_SELINUX_SUFFIX "selinux"
#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
diff --git a/security/integrity/digest_cache/dir.c b/security/integrity/digest_cache/dir.c
index 8f9e550c365f..a292a9c25119 100644
--- a/security/integrity/digest_cache/dir.c
+++ b/security/integrity/digest_cache/dir.c
@@ -56,6 +56,7 @@ static bool digest_cache_dir_iter(struct dir_context *__ctx, const char *name,
new_entry->seq_num = UINT_MAX;
new_entry->digest_cache = NULL;
mutex_init(&new_entry->digest_cache_mutex);
+ new_entry->prefetched = false;
if (new_entry->name[0] < '0' || new_entry->name[0] > '9')
goto out;
@@ -134,6 +135,11 @@ int digest_cache_dir_add_entries(struct digest_cache *digest_cache,
* created/obtained from, so that the caller can use it to perform lookup
* operations.
*
+ * Before creating the digest cache, this function first calls
+ * digest_cache_prefetch_requested() to check if prefetching has been requested
+ * on the directory, and passes the result to digest_cache_create(), so that the
+ * latter sets the DIR_PREFETCH bit in the directory digest cache.
+ *
* Return: A directory digest cache on success, NULL otherwise.
*/
static struct digest_cache *digest_cache_dir_create(struct dentry *dentry,
@@ -142,6 +148,7 @@ static struct digest_cache *digest_cache_dir_create(struct dentry *dentry,
{
struct digest_cache *digest_cache;
struct path _dir_path;
+ bool prefetch_req;
int ret;
ret = kern_path(path_str, 0, &_dir_path);
@@ -150,8 +157,10 @@ static struct digest_cache *digest_cache_dir_create(struct dentry *dentry,
return NULL;
}
+ prefetch_req = digest_cache_prefetch_requested(&_dir_path, path_str);
+
digest_cache = digest_cache_create(dentry, &_dir_path, dir_path,
- path_str, "");
+ path_str, "", prefetch_req, false);
if (digest_cache)
digest_cache = digest_cache_init(dentry, dir_path,
digest_cache);
@@ -204,7 +213,8 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
cache = digest_cache_create(dentry, &dir_path,
&digest_list_path,
dir_cache->path_str,
- dir_entry->name);
+ dir_entry->name, false,
+ false);
if (cache)
cache = digest_cache_init(dentry,
&digest_list_path,
@@ -221,6 +231,8 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
/* Consume extra ref. from digest_cache_create(). */
dir_entry->digest_cache = cache;
+ /* Digest list was read, mark entry as prefetched. */
+ dir_entry->prefetched = true;
}
mutex_unlock(&dir_entry->digest_cache_mutex);
@@ -241,6 +253,125 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
return found;
}
+/**
+ * digest_cache_dir_lookup_filename - Lookup a digest list
+ * @dentry: Dentry of the file whose digest list is looked up
+ * @dir_path: Path structure of the digest list directory
+ * @digest_cache: Dir digest cache
+ * @filename: File name of the digest list to search
+ *
+ * This function iterates over the linked list created by
+ * digest_cache_dir_add_entries() and looks up a digest list with a matching
+ * file name among the entries. If there is no match, it prefetches (reads) the
+ * current digest list. Otherwise, it creates and initializes a new digest
+ * cache.
+ *
+ * The new digest cache is not returned, since it might have been created from
+ * a different inode than the one originally found during digest_cache_create().
+ *
+ * If it is the right one, digest_cache_init() called from digest_cache_get()
+ * will go ahead and simply use the initialized digest cache. If for any reason
+ * the inode was different, digest_cache_init() will use the one previously
+ * returned by digest_cache_create().
+ */
+static void digest_cache_dir_lookup_filename(struct dentry *dentry,
+ struct path *dir_path,
+ struct digest_cache *digest_cache,
+ char *filename)
+{
+ struct digest_cache *cache;
+ struct dir_entry *dir_entry;
+ struct path digest_list_path;
+ bool filename_found;
+
+ list_for_each_entry(dir_entry, &digest_cache->dir_entries, list) {
+ mutex_lock(&dir_entry->digest_cache_mutex);
+ filename_found = !strcmp(dir_entry->name, filename);
+ if (!filename_found && dir_entry->prefetched) {
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+ continue;
+ }
+
+ digest_list_path.dentry = NULL;
+ digest_list_path.mnt = NULL;
+
+ cache = digest_cache_create(dentry, dir_path, &digest_list_path,
+ digest_cache->path_str,
+ dir_entry->name, false,
+ filename_found ? false : true);
+ if (cache)
+ cache = digest_cache_init(dentry, &digest_list_path,
+ cache);
+
+ if (digest_list_path.dentry)
+ path_put(&digest_list_path);
+
+ if (!filename_found)
+ pr_debug("Digest list %s/%s %s prefetched\n",
+ digest_cache->path_str, dir_entry->name,
+ cache ? "has been" : "cannot be");
+
+ if (cache)
+ digest_cache_put(cache);
+
+ dir_entry->prefetched = true;
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+
+ if (filename_found)
+ break;
+ }
+
+ /* Prefetching done, no need to repeat. */
+ clear_bit(FILE_PREFETCH, &digest_cache->flags);
+}
+
+/**
+ * digest_cache_dir_prefetch - Prefetch digest lists in parent directory
+ * @dentry: Dentry of the file whose digest list is looked up
+ * @digest_cache: Digest cache
+ *
+ * This function prefetches the digest lists in the parent directory of the
+ * passed digest cache.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_dir_prefetch(struct dentry *dentry,
+ struct digest_cache *digest_cache)
+{
+ struct digest_cache *dir_cache;
+ char *path_str, *last;
+ struct path dir_path = { .dentry = NULL, .mnt = NULL };
+ int ret = 0;
+
+ last = strrchr(digest_cache->path_str, '/');
+ if (!last)
+ return -EINVAL;
+
+ path_str = kstrndup(digest_cache->path_str,
+ last - digest_cache->path_str, GFP_KERNEL);
+ if (!path_str)
+ return -ENOMEM;
+
+ dir_cache = digest_cache_dir_create(dentry, &dir_path, path_str);
+
+ kfree(path_str);
+
+ if (!dir_cache) {
+ ret = -ENOENT;
+ goto out;
+ }
+
+ digest_cache_dir_lookup_filename(dentry, &dir_path, dir_cache,
+ last + 1);
+
+ digest_cache_put(dir_cache);
+out:
+ if (dir_path.dentry)
+ path_put(&dir_path);
+
+ return ret;
+}
+
/**
* digest_cache_dir_free - Free the stored file list and put digest caches
* @digest_cache: Dir digest cache
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index f849afe5e47b..5af7f6e7bdf6 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -18,6 +18,9 @@
#define INIT_STARTED 1 /* Digest cache init started. */
#define INVALID 2 /* Digest cache marked as invalid. */
#define IS_DIR 3 /* Digest cache created from dir. */
+#define DIR_PREFETCH 4 /* Prefetch enabled for dir. */
+#define FILE_PREFETCH 5 /* Prefetch enabled for dir entry. */
+#define FILE_READ 6 /* Digest cache for reading file. */
/**
* struct readdir_callback - Structure to store information for dir iteration
@@ -38,6 +41,7 @@ struct readdir_callback {
* @digest_cache: Digest cache associated to the directory entry
* @digest_cache_mutex: Protects @digest_cache
* @seq_num: Sequence number of the directory entry from file name
+ * @prefetched: Whether the digest list has been already prefetched
* @name: File name of the directory entry
*
* This structure represents a directory entry with a digest cache created
@@ -48,6 +52,7 @@ struct dir_entry {
struct digest_cache *digest_cache;
struct mutex digest_cache_mutex;
unsigned int seq_num;
+ bool prefetched;
char name[];
};
@@ -219,7 +224,10 @@ digest_cache_from_file_sec(const struct file *file)
struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *default_path,
struct path *digest_list_path,
- char *path_str, char *filename);
+ char *path_str, char *filename,
+ bool prefetch_req, bool prefetch);
+bool digest_cache_prefetch_requested(struct path *digest_list_path,
+ char *path_str);
struct digest_cache *digest_cache_init(struct dentry *dentry,
struct path *digest_list_path,
struct digest_cache *digest_cache);
@@ -255,6 +263,8 @@ struct digest_cache *
digest_cache_dir_lookup_digest(struct dentry *dentry,
struct digest_cache *digest_cache, u8 *digest,
enum hash_algo algo);
+int digest_cache_dir_prefetch(struct dentry *dentry,
+ struct digest_cache *digest_cache);
void digest_cache_dir_free(struct digest_cache *digest_cache);
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index 9df819c323c7..ca1f0bc8ec94 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -86,6 +86,8 @@ static void digest_cache_free(struct digest_cache *digest_cache)
* @digest_list_path: Path structure of the digest list
* @path_str: Path string of the digest list
* @filename: Digest list file name (can be an empty string)
+ * @prefetch_req: Whether prefetching has been requested
+ * @prefetch: Whether prefetching of a digest list is being done
*
* This function first locates, from the passed path and filename, the digest
* list inode from which the digest cache will be created or retrieved (if it
@@ -107,7 +109,8 @@ static void digest_cache_free(struct digest_cache *digest_cache)
struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *default_path,
struct path *digest_list_path,
- char *path_str, char *filename)
+ char *path_str, char *filename,
+ bool prefetch_req, bool prefetch)
{
struct digest_cache *digest_cache = NULL;
struct digest_cache_security *dig_sec;
@@ -160,6 +163,16 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
goto out;
}
+ if (prefetch) {
+ digest_cache = digest_cache_alloc_init(path_str, filename);
+ if (digest_cache) {
+ set_bit(FILE_READ, &digest_cache->flags);
+ goto out_set;
+ }
+
+ goto out;
+ }
+
/* Ref. count is already 1 for this reference. */
dig_sec->dig_owner = digest_cache_alloc_init(path_str, filename);
if (!dig_sec->dig_owner)
@@ -167,14 +180,68 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
/* Increment ref. count for reference returned to the caller. */
digest_cache = digest_cache_ref(dig_sec->dig_owner);
-
+out_set:
/* Make other digest cache requestors wait until creation complete. */
set_bit(INIT_IN_PROGRESS, &digest_cache->flags);
+
+ /* Set bit if prefetching was requested. */
+ if (prefetch_req) {
+ if (S_ISREG(inode->i_mode))
+ set_bit(FILE_PREFETCH, &digest_cache->flags);
+ else
+ set_bit(DIR_PREFETCH, &digest_cache->flags);
+ }
out:
mutex_unlock(&dig_sec->dig_owner_mutex);
return digest_cache;
}
+/**
+ * digest_cache_prefetch_requested - Verify if prefetching is requested
+ * @digest_list_path: Path structure of the digest list directory
+ * @path_str: Path string of the digest list directory
+ *
+ * This function verifies whether or not digest list prefetching is requested.
+ * If dig_owner exists in the inode security blob, it checks the DIR_PREFETCH
+ * bit (faster). Otherwise, it reads the security.dig_prefetch xattr.
+ *
+ * Return: True if prefetching is requested, false otherwise.
+ */
+bool digest_cache_prefetch_requested(struct path *digest_list_path,
+ char *path_str)
+{
+ struct digest_cache_security *dig_sec;
+ bool prefetch_req = false;
+ char prefetch_value;
+ struct inode *inode;
+ int ret;
+
+ inode = d_backing_inode(digest_list_path->dentry);
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ return false;
+
+ mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner) {
+ /* Reliable test: DIR_PREFETCH set with dig_owner_mutex held. */
+ prefetch_req = test_bit(DIR_PREFETCH,
+ &dig_sec->dig_owner->flags);
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+ return prefetch_req;
+ }
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+
+ ret = vfs_getxattr(&nop_mnt_idmap, digest_list_path->dentry,
+ XATTR_NAME_DIG_PREFETCH, &prefetch_value, 1);
+ if (ret == 1 && prefetch_value == '1') {
+ pr_debug("Prefetching has been enabled for directory %s\n",
+ path_str);
+ prefetch_req = true;
+ }
+
+ return prefetch_req;
+}
+
/**
* digest_cache_new - Retrieve digest list file name and request digest cache
* @dentry: Dentry of the inode for which the digest cache will be used
@@ -186,6 +253,12 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
* with that file name. If security.digest_list is empty or not found, this
* function requests the creation of a digest cache on the parent directory.
*
+ * In either case, this function first calls digest_cache_prefetch_requested()
+ * to check if prefetching has been requested on the parent directory, and
+ * passes the result to digest_cache_create(), so that the latter sets the
+ * FILE_PREFETCH and DIR_PREFETCH bit respectively in the file or directory
+ * digest caches.
+ *
* This function passes to the caller the path of the digest list from which
* the digest cache was created (file or parent directory), so that
* digest_cache_init() can reuse the same path, and to prevent the inode from
@@ -199,6 +272,7 @@ static struct digest_cache *digest_cache_new(struct dentry *dentry,
char filename[NAME_MAX + 1] = { 0 };
struct digest_cache *digest_cache = NULL;
struct path default_path;
+ bool prefetch_req = false;
int ret;
ret = kern_path(default_path_str, 0, &default_path);
@@ -244,9 +318,12 @@ static struct digest_cache *digest_cache_new(struct dentry *dentry,
XATTR_NAME_DIGEST_LIST, dentry->d_name.name, default_path_str,
filename);
create:
+ prefetch_req = digest_cache_prefetch_requested(&default_path,
+ default_path_str);
+
digest_cache = digest_cache_create(dentry, &default_path,
digest_list_path, default_path_str,
- filename);
+ filename, prefetch_req, false);
out:
path_put(&default_path);
return digest_cache;
@@ -372,9 +449,20 @@ struct digest_cache *digest_cache_get(struct file *file)
mutex_unlock(&dig_sec->dig_user_mutex);
- if (digest_cache)
+ if (digest_cache) {
+ /*
+ * Prefetching should also initialize our digest cache, if the
+ * path didn't change meanwhile (otherwise the prefetching
+ * mechanism will create and initialize the digest cache of a
+ * different inode).
+ */
+ if (test_bit(FILE_PREFETCH, &digest_cache->flags))
+ digest_cache_dir_prefetch(dentry, digest_cache);
+
+ /* Make sure we initialize our digest cache. */
digest_cache = digest_cache_init(dentry, &digest_list_path,
digest_cache);
+ }
if (digest_list_path.dentry)
path_put(&digest_list_path);
diff --git a/security/integrity/digest_cache/populate.c b/security/integrity/digest_cache/populate.c
index 54f7f95f5794..b1646da07f36 100644
--- a/security/integrity/digest_cache/populate.c
+++ b/security/integrity/digest_cache/populate.c
@@ -11,6 +11,7 @@
#include <linux/init_task.h>
#include <linux/vmalloc.h>
#include <linux/kernel_read_file.h>
+#include <linux/namei.h>
#include "internal.h"
@@ -82,6 +83,12 @@ int digest_cache_populate(struct dentry *dentry,
return ret;
}
+ /* The caller wants just to read digest lists. */
+ if (test_bit(FILE_READ, &digest_cache->flags)) {
+ ret = 0;
+ goto out_vfree;
+ }
+
data_len = digest_cache_strip_modsig(data, ret);
/* Digest list parsers initialize the hash table and add the digests. */
@@ -91,7 +98,7 @@ int digest_cache_populate(struct dentry *dentry,
if (ret < 0)
pr_debug("Error parsing digest list %s, ret: %d\n",
digest_cache->path_str, ret);
-
+out_vfree:
vfree(data);
return ret;
}
diff --git a/security/integrity/digest_cache/verif.c b/security/integrity/digest_cache/verif.c
index 03ebf0de764b..2854bdab3e07 100644
--- a/security/integrity/digest_cache/verif.c
+++ b/security/integrity/digest_cache/verif.c
@@ -44,6 +44,10 @@ int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
gfp_t flags = !strncmp(verif_id, "kprobe", 6) ? GFP_ATOMIC : GFP_KERNEL;
int ret = 0;
+ /* Allows us to detect that we are prefetching in the tests. */
+ if (test_bit(FILE_READ, &digest_cache->flags))
+ return -ENOENT;
+
/*
* Zero the data, so that we can always call free_verif() to free a
* partially filled structure (if a pointer is NULL, will not be freed).
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 13/15] digest_cache: Reset digest cache on file/directory change
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Register six new LSM hooks on behalf of the IMA LSM, path_truncate,
file_release, inode_unlink, inode_rename, inode_post_setxattr and
inode_post_removexattr, to monitor digest lists/parent directory
modifications.
If an action affects a digest list or the parent directory, the new LSM
hook implementations call digest_cache_reset_clear_owner() to set the RESET
bit on the digest cache referenced by dig_owner in the inode security blob,
and to put and clear dig_owner itself. This will also cause next calls to
digest_cache_get() and digest_cache_dir_lookup_digest() to replace
respectively dig_user and the directory entry digest cache.
If an action affects a file using a digest cache, the new LSM hook
implementations call digest_cache_clear_user() to clear dig_user in the
inode security blob. This will also cause next calls to digest_cache_get()
to obtain a new digest cache, based on the updated location.
Recreating a file digest cache means reading the digest list again and
extracting the digests. Recreating a directory digest cache, instead, does
not mean recreating the digest cache for existing directory entries, since
those digest caches are likely already stored in the inode security blob.
It would happen however for new directory entries.
Dig_owner reset and clear for file/directory digest caches is done on
path_truncate, when a digest list is truncated (there is no inode_truncate,
file_truncate does not catch operations through the truncate() system
call), file_release, when a digest list opened for write or created is
being closed, inode_unlink, when a digest list is removed, and inode_rename
when a digest list or the directory itself are renamed.
Directory digest caches are reset even if the current operation involves a
file, since that operation might affect the result of the lookup done
through them. For example, if one wants to know whether a digest is found
or not in a directory, adding a new digest list to that directory could
change the result.
Dig_user clear is always done on inode_post_setxattr and
inode_post_removexattr, when the security.digest_list xattr is respectively
set or removed from a file using a digest cache.
Callers of digest_cache_get() can still keep a digest cache after reset,
since the reference count remains greater than zero even if dig_owner and
dig_user are cleared. However, digest_cache_lookup() will notify the
callers that a reset happened through an error pointer. Callers need to
obtain a fresh digest cache with digest_cache_get() and repeat the lookup
again.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/digest_cache/Makefile | 2 +-
security/integrity/digest_cache/dir.c | 6 +
security/integrity/digest_cache/htable.c | 6 +-
security/integrity/digest_cache/internal.h | 13 ++
security/integrity/digest_cache/main.c | 12 ++
security/integrity/digest_cache/reset.c | 227 +++++++++++++++++++++
6 files changed, 264 insertions(+), 2 deletions(-)
create mode 100644 security/integrity/digest_cache/reset.c
diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile
index d07ac2483504..f8afb85407a0 100644
--- a/security/integrity/digest_cache/Makefile
+++ b/security/integrity/digest_cache/Makefile
@@ -6,6 +6,6 @@ obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
obj-$(CONFIG_DIGEST_CACHE_TLV_PARSER) += parsers/tlv.o
digest_cache-y := main.o secfs.o htable.o parsers.o populate.o modsig.o \
- verif.o dir.o
+ verif.o dir.o reset.o
CFLAGS_parsers.o += -DPARSERS_DIR=\"$(MODLIB)/kernel/security/integrity/digest_cache/parsers\"
diff --git a/security/integrity/digest_cache/dir.c b/security/integrity/digest_cache/dir.c
index a292a9c25119..d4fd5b5ef8fa 100644
--- a/security/integrity/digest_cache/dir.c
+++ b/security/integrity/digest_cache/dir.c
@@ -206,6 +206,12 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
list_for_each_entry(dir_entry, &dir_cache->dir_entries, list) {
mutex_lock(&dir_entry->digest_cache_mutex);
+ if (dir_entry->digest_cache &&
+ test_bit(RESET, &dir_entry->digest_cache->flags)) {
+ digest_cache_put(dir_entry->digest_cache);
+ dir_entry->digest_cache = NULL;
+ }
+
if (!dir_entry->digest_cache) {
digest_list_path.dentry = NULL;
digest_list_path.mnt = NULL;
diff --git a/security/integrity/digest_cache/htable.c b/security/integrity/digest_cache/htable.c
index a01e24d7f198..349aebf91360 100644
--- a/security/integrity/digest_cache/htable.c
+++ b/security/integrity/digest_cache/htable.c
@@ -203,7 +203,8 @@ EXPORT_SYMBOL_GPL(digest_cache_htable_lookup);
* passed digest cache, obtained with digest_cache_get().
*
* Return: A digest cache reference if the digest is found, NULL if not, an
- * error pointer if dir digest cache changed since last get.
+ * error pointer if dir digest cache changed since last get, or digest
+ * cache was reset.
*/
struct digest_cache *digest_cache_lookup(struct dentry *dentry,
struct digest_cache *digest_cache,
@@ -211,6 +212,9 @@ struct digest_cache *digest_cache_lookup(struct dentry *dentry,
{
int ret;
+ if (test_bit(RESET, &digest_cache->flags))
+ return ERR_PTR(-EAGAIN);
+
if (test_bit(IS_DIR, &digest_cache->flags))
return digest_cache_dir_lookup_digest(dentry, digest_cache,
digest, algo);
diff --git a/security/integrity/digest_cache/internal.h b/security/integrity/digest_cache/internal.h
index 5af7f6e7bdf6..75f8b118c3db 100644
--- a/security/integrity/digest_cache/internal.h
+++ b/security/integrity/digest_cache/internal.h
@@ -21,6 +21,7 @@
#define DIR_PREFETCH 4 /* Prefetch enabled for dir. */
#define FILE_PREFETCH 5 /* Prefetch enabled for dir entry. */
#define FILE_READ 6 /* Digest cache for reading file. */
+#define RESET 7 /* Digest cache to be recreated. */
/**
* struct readdir_callback - Structure to store information for dir iteration
@@ -267,4 +268,16 @@ int digest_cache_dir_prefetch(struct dentry *dentry,
struct digest_cache *digest_cache);
void digest_cache_dir_free(struct digest_cache *digest_cache);
+/* reset.c */
+int digest_cache_path_truncate(const struct path *path);
+void digest_cache_file_release(struct file *file);
+int digest_cache_inode_unlink(struct inode *dir, struct dentry *dentry);
+int digest_cache_inode_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry);
+void digest_cache_inode_post_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size,
+ int flags);
+void digest_cache_inode_post_removexattr(struct dentry *dentry,
+ const char *name);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/integrity/digest_cache/main.c b/security/integrity/digest_cache/main.c
index ca1f0bc8ec94..0a167c82e308 100644
--- a/security/integrity/digest_cache/main.c
+++ b/security/integrity/digest_cache/main.c
@@ -436,6 +436,11 @@ struct digest_cache *digest_cache_get(struct file *file)
/* Serialize accesses to inode for which the digest cache is used. */
mutex_lock(&dig_sec->dig_user_mutex);
+ if (dig_sec->dig_user && test_bit(RESET, &dig_sec->dig_user->flags)) {
+ digest_cache_put(dig_sec->dig_user);
+ dig_sec->dig_user = NULL;
+ }
+
if (!dig_sec->dig_user) {
down_read(&default_path_sem);
/* Consume extra reference from digest_cache_create(). */
@@ -553,6 +558,13 @@ static struct security_hook_list digest_cache_hooks[] __ro_after_init = {
LSM_HOOK_INIT(inode_alloc_security, digest_cache_inode_alloc_security),
LSM_HOOK_INIT(inode_free_security_rcu,
digest_cache_inode_free_security_rcu),
+ LSM_HOOK_INIT(path_truncate, digest_cache_path_truncate),
+ LSM_HOOK_INIT(file_release, digest_cache_file_release),
+ LSM_HOOK_INIT(inode_unlink, digest_cache_inode_unlink),
+ LSM_HOOK_INIT(inode_rename, digest_cache_inode_rename),
+ LSM_HOOK_INIT(inode_post_setxattr, digest_cache_inode_post_setxattr),
+ LSM_HOOK_INIT(inode_post_removexattr,
+ digest_cache_inode_post_removexattr),
};
/**
diff --git a/security/integrity/digest_cache/reset.c b/security/integrity/digest_cache/reset.c
new file mode 100644
index 000000000000..003c8ee96d72
--- /dev/null
+++ b/security/integrity/digest_cache/reset.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Reset digest cache on digest lists/directory modifications.
+ */
+
+#define pr_fmt(fmt) "digest_cache: "fmt
+#include "internal.h"
+
+/**
+ * digest_cache_reset_clear_owner - Reset and clear dig_owner
+ * @inode: Inode of the digest list/directory containing the digest list
+ * @reason: Reason for reset and clear
+ *
+ * This function sets the RESET bit of the digest cache referenced by dig_owner
+ * of the passed inode, and puts and clears dig_owner.
+ *
+ * The next time they are called, digest_cache_get() and
+ * digest_cache_dir_lookup_digest() replace respectively dig_user and the digest
+ * cache of the directory entry.
+ */
+static void digest_cache_reset_clear_owner(struct inode *inode,
+ const char *reason)
+{
+ struct digest_cache_security *dig_sec;
+
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ return;
+
+ mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner) {
+ pr_debug("Resetting and clearing %s (dig_owner), reason: %s\n",
+ dig_sec->dig_owner->path_str, reason);
+ set_bit(RESET, &dig_sec->dig_owner->flags);
+ digest_cache_put(dig_sec->dig_owner);
+ dig_sec->dig_owner = NULL;
+ }
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+}
+
+/**
+ * digest_cache_clear_user - Clear dig_user
+ * @inode: Inode of the file using the digest cache
+ * @filename: File name of the affected inode
+ * @reason: Reason for clear
+ *
+ * This function clears dig_user in the inode security blob, so that
+ * digest_cache_get() requests a new digest cache based on the updated digest
+ * list location.
+ */
+static void digest_cache_clear_user(struct inode *inode, const char *filename,
+ const char *reason)
+{
+ struct digest_cache_security *dig_sec;
+
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ return;
+
+ mutex_lock(&dig_sec->dig_user_mutex);
+ if (dig_sec->dig_user && !test_bit(RESET, &dig_sec->dig_user->flags)) {
+ pr_debug("Clearing %s (dig_user of %s), reason: %s\n",
+ dig_sec->dig_user->path_str, filename, reason);
+ digest_cache_put(dig_sec->dig_user);
+ dig_sec->dig_user = NULL;
+ }
+ mutex_unlock(&dig_sec->dig_user_mutex);
+}
+
+/**
+ * digest_cache_path_truncate - A file is being truncated
+ * @path: File path
+ *
+ * This function is called when a file is being truncated. If the inode is a
+ * digest list and/or the parent is a directory containing digest lists, it
+ * resets the inode and/or directory dig_owner, to force rebuilding the digest
+ * cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_path_truncate(const struct path *path)
+{
+ struct inode *inode = d_backing_inode(path->dentry);
+ struct inode *dir = d_backing_inode(path->dentry->d_parent);
+
+ if (!S_ISREG(inode->i_mode))
+ return 0;
+
+ digest_cache_reset_clear_owner(inode, "path_truncate(file)");
+ digest_cache_reset_clear_owner(dir, "path_truncate(dir)");
+ return 0;
+}
+
+/**
+ * digest_cache_file_release - Last reference of a file desc is being released
+ * @file: File descriptor
+ *
+ * This function is called when the last reference of a file descriptor is
+ * being released. If the inode is a regular file and was opened for write or
+ * was created, it resets the inode and the parent directory dig_owner, to
+ * force rebuilding the digest caches.
+ */
+void digest_cache_file_release(struct file *file)
+{
+ struct inode *dir = d_backing_inode(file_dentry(file)->d_parent);
+
+ if (!S_ISREG(file_inode(file)->i_mode) ||
+ ((!(file->f_mode & FMODE_WRITE)) &&
+ !(file->f_mode & FMODE_CREATED)))
+ return;
+
+ digest_cache_reset_clear_owner(file_inode(file), "file_release(file)");
+ digest_cache_reset_clear_owner(dir, "file_release(dir)");
+}
+
+/**
+ * digest_cache_inode_unlink - An inode is being removed
+ * @dir: Inode of the affected directory
+ * @dentry: Dentry of the inode being removed
+ *
+ * This function is called when an existing inode is being removed. If the
+ * inode is a digest list/digest list directory, or the parent inode is the
+ * digest list directory and the inode is a regular file, it resets the
+ * affected inode dig_owner, to force rebuilding the digest cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_inode_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+
+ if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+ return 0;
+
+ digest_cache_reset_clear_owner(inode, S_ISREG(inode->i_mode) ?
+ "inode_unlink(file)" :
+ "inode_unlink(dir)");
+
+ if (S_ISREG(inode->i_mode))
+ digest_cache_reset_clear_owner(dir, "inode_unlink(dir)");
+
+ return 0;
+}
+
+/**
+ * digest_cache_inode_rename - An inode is being renamed
+ * @old_dir: Inode of the directory containing the inode being renamed
+ * @old_dentry: Dentry of the inode being renamed
+ * @new_dir: Directory where the inode will be placed into
+ * @new_dentry: Dentry of the inode after being renamed
+ *
+ * This function is called when an existing inode is being moved from a
+ * directory to another (rename). If the inode is a digest list or the digest
+ * list directory, or that inode is a digest list moved from/to the digest list
+ * directory, it resets the affected inode dig_owner, to force rebuilding the
+ * digest cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_inode_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *old_inode = d_backing_inode(old_dentry);
+
+ if (!S_ISREG(old_inode->i_mode) && !S_ISDIR(old_inode->i_mode))
+ return 0;
+
+ digest_cache_reset_clear_owner(old_inode, S_ISREG(old_inode->i_mode) ?
+ "inode_rename(file)" :
+ "inode_rename(dir)");
+
+ if (S_ISREG(old_inode->i_mode)) {
+ digest_cache_reset_clear_owner(old_dir,
+ "inode_rename(from_dir)");
+ digest_cache_reset_clear_owner(new_dir,
+ "inode_rename(to_dir)");
+ }
+
+ return 0;
+}
+
+/**
+ * digest_cache_inode_post_setxattr - An xattr was set
+ * @dentry: File
+ * @name: Xattr name
+ * @value: Xattr value
+ * @size: Size of xattr value
+ * @flags: Flags
+ *
+ * This function is called after an xattr was set on an existing inode. If the
+ * inode points to a digest cache and the xattr set is security.digest_list, it
+ * puts and clears dig_user in the inode security blob, to force retrieving a
+ * fresh digest cache.
+ */
+void digest_cache_inode_post_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ if (strcmp(name, XATTR_NAME_DIGEST_LIST))
+ return;
+
+ digest_cache_clear_user(d_backing_inode(dentry), dentry->d_name.name,
+ "inode_post_setxattr");
+}
+
+/**
+ * digest_cache_inode_post_removexattr - An xattr was removed
+ * @dentry: File
+ * @name: Xattr name
+ *
+ * This function is called after an xattr was removed from an existing inode.
+ * If the inode points to a digest cache and the xattr removed is
+ * security.digest_list, it puts and clears dig_user in the inode security
+ * blob, to force retrieving a fresh digest cache.
+ */
+void digest_cache_inode_post_removexattr(struct dentry *dentry,
+ const char *name)
+{
+ if (strcmp(name, XATTR_NAME_DIGEST_LIST))
+ return;
+
+ digest_cache_clear_user(d_backing_inode(dentry), dentry->d_name.name,
+ "inode_post_removexattr");
+}
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 14/15] selftests/digest_cache: Add selftests for the Integrity Digest Cache
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add tests to verify the correctness of the Integrity Digest Cache, in
all_test.c.
Add the kernel module digest_cache_kern.ko, to let all_test call the API
of the Integrity Digest Cache through the newly introduced
digest_cache_test file in <securityfs>/integrity/digest_cache.
Test coverage information:
File 'security/integrity/digest_cache/reset.c'
Lines executed:100.00% of 53
File 'security/integrity/digest_cache/main.c'
Lines executed:90.29% of 206
File 'security/integrity/digest_cache/modsig.c'
Lines executed:42.86% of 21
File 'security/integrity/digest_cache/htable.c'
Lines executed:93.90% of 82
File 'security/integrity/digest_cache/populate.c'
Lines executed:89.19% of 37
File 'security/integrity/digest_cache/verif.c'
Lines executed:85.11% of 47
File 'security/integrity/digest_cache/dir.c'
Lines executed:90.18% of 163
File 'security/integrity/digest_cache/parsers.c'
Lines executed:45.74% of 94
File 'security/integrity/digest_cache/secfs.c'
Lines executed:56.00% of 25
File 'security/integrity/digest_cache/parsers/tlv.c'
Lines executed:75.26% of 97
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
tools/testing/selftests/Makefile | 1 +
.../testing/selftests/digest_cache/.gitignore | 3 +
tools/testing/selftests/digest_cache/Makefile | 24 +
.../testing/selftests/digest_cache/all_test.c | 769 ++++++++++++++++++
tools/testing/selftests/digest_cache/common.c | 78 ++
tools/testing/selftests/digest_cache/common.h | 93 +++
.../selftests/digest_cache/common_user.c | 33 +
.../selftests/digest_cache/common_user.h | 15 +
tools/testing/selftests/digest_cache/config | 2 +
.../selftests/digest_cache/generators.c | 130 +++
.../selftests/digest_cache/generators.h | 16 +
.../selftests/digest_cache/testmod/Makefile | 16 +
.../selftests/digest_cache/testmod/kern.c | 551 +++++++++++++
13 files changed, 1731 insertions(+)
create mode 100644 tools/testing/selftests/digest_cache/.gitignore
create mode 100644 tools/testing/selftests/digest_cache/Makefile
create mode 100644 tools/testing/selftests/digest_cache/all_test.c
create mode 100644 tools/testing/selftests/digest_cache/common.c
create mode 100644 tools/testing/selftests/digest_cache/common.h
create mode 100644 tools/testing/selftests/digest_cache/common_user.c
create mode 100644 tools/testing/selftests/digest_cache/common_user.h
create mode 100644 tools/testing/selftests/digest_cache/config
create mode 100644 tools/testing/selftests/digest_cache/generators.c
create mode 100644 tools/testing/selftests/digest_cache/generators.h
create mode 100644 tools/testing/selftests/digest_cache/testmod/Makefile
create mode 100644 tools/testing/selftests/digest_cache/testmod/kern.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index b38199965f99..e6fc3c984923 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -16,6 +16,7 @@ TARGETS += cpu-hotplug
TARGETS += damon
TARGETS += devices/error_logs
TARGETS += devices/probe
+TARGETS += digest_cache
TARGETS += dmabuf-heaps
TARGETS += drivers/dma-buf
TARGETS += drivers/s390x/uvdevice
diff --git a/tools/testing/selftests/digest_cache/.gitignore b/tools/testing/selftests/digest_cache/.gitignore
new file mode 100644
index 000000000000..392096e18f4e
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/.gitignore
@@ -0,0 +1,3 @@
+/*.mod
+/*_test
+/*.ko
diff --git a/tools/testing/selftests/digest_cache/Makefile b/tools/testing/selftests/digest_cache/Makefile
new file mode 100644
index 000000000000..1b819201f406
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/Makefile
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS_EXTENDED = digest_cache_kern.ko
+TEST_GEN_PROGS := all_test
+
+$(OUTPUT)/%.ko: $(wildcard common.[ch]) testmod/Makefile testmod/kern.c
+ $(call msg,MOD,,$@)
+ $(Q)$(MAKE) -C testmod
+ $(Q)cp testmod/digest_cache_kern.ko $@
+
+LOCAL_HDRS += common.h common_user.h generators.h
+CFLAGS += -ggdb -Wall -Wextra $(KHDR_INCLUDES)
+
+OVERRIDE_TARGETS := 1
+override define CLEAN
+ $(call msg,CLEAN)
+ $(Q)$(MAKE) -C testmod clean
+ rm -Rf $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED)
+ rm -Rf $(OUTPUT)/common.o $(OUTPUT)/common_user.o $(OUTPUT)/generators.o
+ rm -Rf $(OUTPUT)/common.mod
+endef
+
+include ../lib.mk
+
+$(OUTPUT)/all_test: common.c common.h common_user.c common_user.h generators.c
diff --git a/tools/testing/selftests/digest_cache/all_test.c b/tools/testing/selftests/digest_cache/all_test.c
new file mode 100644
index 000000000000..a283068f3cab
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/all_test.c
@@ -0,0 +1,769 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the tests of the Integrity Digest Cache.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <fts.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/xattr.h>
+#include <sys/syscall.h>
+#include <linux/module.h>
+
+#include "generators.h"
+
+#include "../kselftest_harness.h"
+#include "../../../../include/uapi/linux/xattr.h"
+
+#define BASE_DIR_TEMPLATE "/tmp/digest_cache_test_dirXXXXXX"
+#define DIGEST_LISTS_SUBDIR "digest_lists"
+#define NUM_DIGEST_LISTS_PREFETCH MAX_WORKS
+
+FIXTURE(shared_data) {
+ char base_dir[sizeof(BASE_DIR_TEMPLATE)];
+ char digest_lists_dir[sizeof(BASE_DIR_TEMPLATE) +
+ sizeof(DIGEST_LISTS_SUBDIR)];
+ int base_dirfd, digest_lists_dirfd, kernfd, pathfd, cmd_len, no_kprobe;
+};
+
+FIXTURE_SETUP(shared_data)
+{
+ char cmd[1024];
+ int ret, fd, i, cmd_len;
+
+ /* Create the base directory. */
+ snprintf(self->base_dir, sizeof(self->base_dir), BASE_DIR_TEMPLATE);
+ ASSERT_NE(NULL, mkdtemp(self->base_dir));
+
+ /* Open base directory. */
+ self->base_dirfd = open(self->base_dir, O_RDONLY | O_DIRECTORY);
+ ASSERT_NE(-1, self->base_dirfd);
+
+ /* Create the digest_lists subdirectory. */
+ snprintf(self->digest_lists_dir, sizeof(self->digest_lists_dir),
+ "%s/%s", self->base_dir, DIGEST_LISTS_SUBDIR);
+ ASSERT_EQ(0, mkdirat(self->base_dirfd, DIGEST_LISTS_SUBDIR, 0600));
+ self->digest_lists_dirfd = openat(self->base_dirfd, DIGEST_LISTS_SUBDIR,
+ O_RDONLY | O_DIRECTORY);
+ ASSERT_NE(-1, self->digest_lists_dirfd);
+
+ fd = open("digest_cache_kern.ko", O_RDONLY);
+ ASSERT_LT(0, fd);
+
+ ASSERT_EQ(0, syscall(SYS_finit_module, fd, "", 0));
+ close(fd);
+
+ /* Open kernel test interface. */
+ self->kernfd = open(DIGEST_CACHE_TEST_INTERFACE, O_RDWR, 0600);
+ ASSERT_NE(-1, self->kernfd);
+
+ /* Open kernel digest list path interface. */
+ self->pathfd = open(DIGEST_CACHE_PATH_INTERFACE, O_RDWR, 0600);
+ ASSERT_NE(-1, self->pathfd);
+
+ /* Write the path of the digest lists directory. */
+ ASSERT_LT(0, write(self->pathfd, self->digest_lists_dir,
+ strlen(self->digest_lists_dir)));
+
+ /* Ensure that no verifier is enabled at the beginning of a test. */
+ for (i = 0; i < VERIF__LAST; i++) {
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_DISABLE_VERIF],
+ verifs_str[i]);
+ ret = write(self->kernfd, cmd, cmd_len);
+ if (ret < 0 && errno == EOPNOTSUPP) {
+ self->no_kprobe = 1;
+ break;
+ }
+
+ ASSERT_EQ(cmd_len, ret);
+ }
+}
+
+FIXTURE_TEARDOWN(shared_data)
+{
+ FTS *fts = NULL;
+ FTSENT *ftsent;
+ int fts_flags = (FTS_PHYSICAL | FTS_COMFOLLOW | FTS_NOCHDIR | FTS_XDEV);
+ char *paths[2] = { self->base_dir, NULL };
+ char cmd[1024];
+ int cmd_len;
+
+ /* Close digest_lists subdirectory. */
+ close(self->digest_lists_dirfd);
+
+ /* Close base directory. */
+ close(self->base_dirfd);
+
+ /* Delete files and directories. */
+ fts = fts_open(paths, fts_flags, NULL);
+ if (fts) {
+ while ((ftsent = fts_read(fts)) != NULL) {
+ switch (ftsent->fts_info) {
+ case FTS_DP:
+ rmdir(ftsent->fts_accpath);
+ break;
+ case FTS_F:
+ case FTS_SL:
+ case FTS_SLNONE:
+ case FTS_DEFAULT:
+ unlink(ftsent->fts_accpath);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+
+ /* Release digest cache reference, if the test was interrupted. */
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+
+ /* Close kernel test interface. */
+ close(self->kernfd);
+
+ /* Close kernel digest list path interface. */
+ close(self->pathfd);
+
+ syscall(SYS_delete_module, "digest_cache_kern", 0);
+}
+
+static int _query_test(int kernfd, char *base_dir, char *filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ bool write_digest_list, int digest_lists_dirfd,
+ char *digest_list_filename)
+{
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ char digest_str[MAX_DIGEST_SIZE * 2 + 1] = { 0 };
+ int digest_len = hash_digest_size[algo];
+ char cmd[1024];
+ int ret, fd, i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s",
+ commands_str[DIGEST_CACHE_GET], base_dir, filename);
+ ret = write(kernfd, cmd, cmd_len);
+ if (ret != cmd_len)
+ return -errno;
+
+ if (write_digest_list) {
+ fd = openat(digest_lists_dirfd, digest_list_filename, O_WRONLY);
+ if (fd < 0)
+ return -errno;
+
+ close(fd);
+ }
+
+ ret = 0;
+
+ *(u32 *)digest = start_number;
+
+ for (i = 0; i < num_digests; i++) {
+ bin2hex(digest_str, digest, digest_len);
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s|%s:%s",
+ commands_str[DIGEST_CACHE_LOOKUP], base_dir,
+ filename, hash_algo_name[algo], digest_str);
+ ret = write(kernfd, cmd, cmd_len);
+ if (ret != cmd_len) {
+ ret = -errno;
+ goto out;
+ } else {
+ ret = 0;
+ }
+
+ (*(u32 *)digest)++;
+ }
+out:
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(kernfd, cmd, cmd_len);
+ return ret;
+}
+
+static int query_test(int kernfd, char *base_dir, char *filename,
+ enum hash_algo algo, int start_number, int num_digests)
+{
+ return _query_test(kernfd, base_dir, filename, algo, start_number,
+ num_digests, false, -1, NULL);
+}
+
+static int query_test_write(int kernfd, char *base_dir, char *filename,
+ enum hash_algo algo, int start_number,
+ int num_digests, int digest_lists_dirfd,
+ char *digest_list_filename)
+{
+ return _query_test(kernfd, base_dir, filename, algo, start_number,
+ num_digests, true, digest_lists_dirfd,
+ digest_list_filename);
+}
+
+static void test_parser(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ char *digest_list_filename, char *filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ unsigned int failure)
+{
+ int expected_ret = (failure) ? -ENOENT : 0;
+
+ if (!strncmp(digest_list_filename, "tlv-", 4)) {
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, algo,
+ start_number, num_digests,
+ (enum tlv_failures)failure));
+ }
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+ ASSERT_EQ(expected_ret, query_test(self->kernfd, self->base_dir,
+ filename, algo, start_number,
+ num_digests));
+
+ unlinkat(self->digest_lists_dirfd, digest_list_filename, 0);
+ unlinkat(self->base_dirfd, filename, 0);
+}
+
+/*
+ * Verify that the tlv digest list parser returns success on well-formatted
+ * digest lists, for each defined hash algorithm.
+ */
+TEST_F(shared_data, tlv_parser_ok)
+{
+ enum hash_algo algo;
+
+ /* Test every known algorithm. */
+ for (algo = 0; algo < HASH_ALGO__LAST; algo++)
+ test_parser(self, _metadata, "tlv-digest_list", "file", algo,
+ 0, 5, TLV_NO_FAILURE);
+}
+
+/*
+ * Verify that the tlv digest list parser returns failure on invalid digest
+ * lists.
+ */
+TEST_F(shared_data, tlv_parser_error)
+{
+ enum tlv_failures failure;
+
+ /* Test every failure. */
+ for (failure = 0; failure < TLV_FAILURE__LAST; failure++)
+ test_parser(self, _metadata, "tlv-digest_list", "file",
+ HASH_ALGO_SHA224, 0, 1, failure);
+}
+
+static void test_default_path(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata, bool file)
+{
+ char path[PATH_MAX];
+ size_t path_len;
+
+ if (file) {
+ path_len = snprintf(path, sizeof(path),
+ "%s/%s/tlv-digest_list", self->base_dir,
+ DIGEST_LISTS_SUBDIR);
+ ASSERT_LT(0, write(self->pathfd, path, path_len));
+ }
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd, "tlv-digest_list",
+ HASH_ALGO_SHA1, 0, 1, TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", NULL));
+
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+}
+
+/*
+ * Verify that the digest cache created from the default path (regular file)
+ * can be retrieved and used for lookup.
+ */
+TEST_F(shared_data, default_path_file)
+{
+ test_default_path(self, _metadata, true);
+}
+
+/*
+ * Verify that the digest cache created from the default path (directory)
+ * can be retrieved and used for lookup.
+ */
+TEST_F(shared_data, default_path_dir)
+{
+ test_default_path(self, _metadata, false);
+}
+
+static void test_file_changes(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ enum file_changes change)
+{
+ char digest_list_filename[] = "tlv-digest_list";
+ char digest_list_filename_new[] = "tlv-digest_list6";
+ char digest_list_filename_xattr[] = "tlv-digest_list7";
+ char digest_list_path[sizeof(self->digest_lists_dir) +
+ sizeof(digest_list_filename)];
+ int fd;
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1, 0, 1,
+ TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file",
+ digest_list_filename));
+
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+
+ switch (change) {
+ case FILE_WRITE:
+ fd = openat(self->digest_lists_dirfd, digest_list_filename,
+ O_WRONLY);
+ ASSERT_NE(-1, fd);
+
+ ASSERT_EQ(4, write(fd, "1234", 4));
+ close(fd);
+ break;
+ case FILE_TRUNCATE:
+ snprintf(digest_list_path, sizeof(digest_list_path),
+ "%s/%s", self->digest_lists_dir, digest_list_filename);
+ ASSERT_EQ(0, truncate(digest_list_path, 4));
+ break;
+ case FILE_FTRUNCATE:
+ fd = openat(self->digest_lists_dirfd, digest_list_filename,
+ O_WRONLY);
+ ASSERT_NE(-1, fd);
+ ASSERT_EQ(0, ftruncate(fd, 4));
+ close(fd);
+ break;
+ case FILE_UNLINK:
+ ASSERT_EQ(0, unlinkat(self->digest_lists_dirfd,
+ digest_list_filename, 0));
+ break;
+ case FILE_RENAME:
+ ASSERT_EQ(0, renameat(self->digest_lists_dirfd,
+ digest_list_filename,
+ self->digest_lists_dirfd,
+ digest_list_filename_new));
+ break;
+ case FILE_SETXATTR:
+ fd = openat(self->base_dirfd, "file", O_WRONLY);
+ ASSERT_NE(-1, fd);
+
+ ASSERT_EQ(0, fsetxattr(fd, XATTR_NAME_DIGEST_LIST,
+ digest_list_filename_xattr,
+ strlen(digest_list_filename_xattr) + 1,
+ 0));
+ close(fd);
+ break;
+ case FILE_REMOVEXATTR:
+ fd = openat(self->base_dirfd, "file", O_WRONLY);
+ ASSERT_NE(-1, fd);
+
+ ASSERT_EQ(0, fremovexattr(fd, XATTR_NAME_DIGEST_LIST));
+ close(fd);
+
+ /*
+ * Removing security.digest_list does not cause a failure,
+ * the digest can be still retrieved via directory lookup.
+ */
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+
+ return;
+ default:
+ break;
+ }
+
+ ASSERT_NE(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+}
+
+/*
+ * Verify that operations on a digest list cause a reset of the digest cache,
+ * and that the digest is not found in the invalid/missing digest list.
+ */
+TEST_F(shared_data, file_reset)
+{
+ enum file_changes change;
+
+ /* Test for every file change. */
+ for (change = 0; change < FILE_CHANGE__LAST; change++)
+ test_file_changes(self, _metadata, change);
+}
+
+/*
+ * Verify that digest lookup does not work after a reset, and attempt the
+ * query a second time, which should instead succeed.
+ */
+TEST_F(shared_data, file_reset_again)
+{
+ char digest_list_filename[] = "tlv-digest_list";
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1, 0, 1,
+ TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file",
+ digest_list_filename));
+
+ ASSERT_NE(0, query_test_write(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1,
+ self->digest_lists_dirfd,
+ digest_list_filename));
+
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+}
+
+static void query_test_with_failures(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ int start_number, int num_digests,
+ int *removed, int num_removed)
+{
+ char filename[NAME_MAX + 1];
+ int i, j, expected_ret;
+
+ for (i = start_number; i < start_number + num_digests; i++) {
+ expected_ret = 0;
+
+ for (j = 0; j < num_removed; j++) {
+ if (removed[j] == i) {
+ expected_ret = -ENOENT;
+ break;
+ }
+ }
+
+ snprintf(filename, sizeof(filename), "file%d", i);
+
+ ASSERT_EQ(expected_ret, query_test(self->kernfd, self->base_dir,
+ filename, HASH_ALGO_SHA1, i,
+ 1));
+ }
+}
+
+/*
+ * Verify that changes in the digest list directory are monitored and that
+ * a digest cannot be found if the respective digest list file has been moved
+ * away from the directory, and that a digest can be found if the respective
+ * digest list has been moved/created in the directory.
+ */
+TEST_F(shared_data, dir_reset)
+{
+ char filename[NAME_MAX + 1];
+ int i, removed[10];
+
+ for (i = 0; i < 10; i++) {
+ snprintf(filename, sizeof(filename), "file%d", i);
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename, NULL));
+ snprintf(filename, sizeof(filename), "tlv-digest_list%d", i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ filename, HASH_ALGO_SHA1, i, 1,
+ TLV_NO_FAILURE));
+ }
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 0);
+
+ ASSERT_EQ(0, unlinkat(self->digest_lists_dirfd, "tlv-digest_list7", 0));
+
+ removed[0] = 7;
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 1);
+
+ ASSERT_EQ(0, renameat(self->digest_lists_dirfd, "tlv-digest_list6",
+ self->base_dirfd, "tlv-digest_list6"));
+
+ removed[1] = 6;
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 2);
+
+ ASSERT_EQ(0, renameat(self->base_dirfd, "tlv-digest_list6",
+ self->digest_lists_dirfd, "tlv-digest_list6"));
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 1);
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file10", NULL));
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd, "tlv-digest_list10",
+ HASH_ALGO_SHA1, 10, 1, TLV_NO_FAILURE));
+
+ query_test_with_failures(self, _metadata, 0, 11, removed, 1);
+}
+
+static void _check_verif_data(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ char *digest_list_filename, int num,
+ enum hash_algo algo, bool check_dir)
+{
+ char digest_list_filename_kernel[NAME_MAX + 1];
+ char cmd[1024], number[20];
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ char digest_str[MAX_DIGEST_SIZE * 2 + 1] = { 0 };
+ int len, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file",
+ commands_str[DIGEST_CACHE_GET], self->base_dir);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ /*
+ * If a directory digest cache was requested, we need to do a lookup,
+ * to make the kernel module retrieve verification data from the digest
+ * cache of the directory entry.
+ */
+ if (check_dir) {
+ *(u32 *)digest = num;
+
+ bin2hex(digest_str, digest, hash_digest_size[algo]);
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file|%s:%s",
+ commands_str[DIGEST_CACHE_LOOKUP],
+ self->base_dir, hash_algo_name[algo],
+ digest_str);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+ }
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_FILENAMES]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_list_filename_kernel,
+ sizeof(digest_list_filename_kernel)));
+ ASSERT_EQ(0, strcmp(digest_list_filename, digest_list_filename_kernel));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_NUMBER]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ len = read(self->kernfd, number, sizeof(number) - 1);
+ ASSERT_LT(0, len);
+ number[len] = '\0';
+ ASSERT_EQ(num, atoi(number));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+}
+
+static void check_verif_data(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1];
+ char cmd[1024];
+ int i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_FILENAMES]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_NUMBER]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ /*
+ * Reverse order is intentional, so that directory entries are created
+ * in the opposite order as when they are searched (when prefetching is
+ * requested).
+ */
+ for (i = 10; i >= 0; i--) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1,
+ i, 1, TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file",
+ digest_list_filename));
+
+ _check_verif_data(self, _metadata, digest_list_filename, i,
+ HASH_ALGO_SHA1, false);
+
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, "file", 0));
+ }
+
+ for (i = 0; i < 11; i++) {
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", NULL));
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ _check_verif_data(self, _metadata, digest_list_filename, i,
+ HASH_ALGO_SHA1, true);
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, "file", 0));
+ }
+}
+
+/*
+ * Verify that the correct verification data can be retrieved from the digest
+ * caches (without digest list prefetching).
+ */
+TEST_F(shared_data, verif_data_no_prefetch)
+{
+ if (self->no_kprobe)
+ SKIP(return, "CONFIG_DYNAMIC_FTRACE_WITH_ARGS not enabled");
+
+ check_verif_data(self, _metadata);
+}
+
+/*
+ * Verify that the correct verification data can be retrieved from the digest
+ * caches (with digest list prefetching).
+ */
+TEST_F(shared_data, verif_data_prefetch)
+{
+ if (self->no_kprobe)
+ SKIP(return, "CONFIG_DYNAMIC_FTRACE_WITH_ARGS not enabled");
+
+ ASSERT_EQ(0, lsetxattr(self->base_dir, XATTR_NAME_DIG_PREFETCH,
+ "1", 1, 0));
+
+ check_verif_data(self, _metadata);
+}
+
+static void check_prefetch_list(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ int start_number, int end_number)
+{
+ char digest_list_filename[NAME_MAX + 1], filename[NAME_MAX + 1];
+ char digest_lists[1024] = { 0 }, digest_lists_kernel[1024];
+ char cmd[1024];
+ int i, cmd_len;
+
+ snprintf(filename, sizeof(filename), "file%d", end_number);
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", end_number, end_number);
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s",
+ commands_str[DIGEST_CACHE_GET], self->base_dir,
+ filename);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_lists_kernel,
+ sizeof(digest_lists_kernel)));
+
+ for (i = start_number; i <= end_number; i++) {
+ if (digest_lists[0])
+ strcat(digest_lists, ",");
+
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ strcat(digest_lists, digest_list_filename);
+ }
+
+ ASSERT_EQ(0, strcmp(digest_lists, digest_lists_kernel));
+
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, filename, 0));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+}
+
+static void check_prefetch_list_async(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1], filename[NAME_MAX + 1];
+ char digest_lists[1024] = { 0 }, digest_lists_kernel[1024];
+ char cmd[1024];
+ int i, cmd_len;
+
+ for (i = 0; i < NUM_DIGEST_LISTS_PREFETCH; i++) {
+ snprintf(filename, sizeof(filename), "file%d",
+ NUM_DIGEST_LISTS_PREFETCH - 1 - i);
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+ }
+
+ /* Do batch of get/put to test the kernel for concurrent requests. */
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file|%d|%d",
+ commands_str[DIGEST_CACHE_GET_PUT_ASYNC],
+ self->base_dir, 0, NUM_DIGEST_LISTS_PREFETCH - 1);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_lists_kernel,
+ sizeof(digest_lists_kernel)));
+
+ for (i = 0; i < NUM_DIGEST_LISTS_PREFETCH; i++) {
+ if (digest_lists[0])
+ strcat(digest_lists, ",");
+
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ strcat(digest_lists, digest_list_filename);
+ }
+
+ ASSERT_EQ(0, strcmp(digest_lists, digest_lists_kernel));
+}
+
+static void prepare_prefetch(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1];
+ char cmd[1024];
+ int i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_PREFETCH]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_PREFETCH]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ for (i = NUM_DIGEST_LISTS_PREFETCH - 1; i >= 0; i--) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1,
+ i, 1, TLV_NO_FAILURE));
+ }
+
+ ASSERT_EQ(0, fsetxattr(self->digest_lists_dirfd,
+ XATTR_NAME_DIG_PREFETCH, "1", 1, 0));
+}
+
+/*
+ * Verify that digest lists are prefetched when requested, in the correct order
+ * (synchronous version).
+ */
+TEST_F(shared_data, prefetch_sync)
+{
+ int i;
+
+ if (self->no_kprobe)
+ SKIP(return, "CONFIG_DYNAMIC_FTRACE_WITH_ARGS not enabled");
+
+ prepare_prefetch(self, _metadata);
+
+ for (i = 2; i < NUM_DIGEST_LISTS_PREFETCH; i += 3)
+ check_prefetch_list(self, _metadata, i - 2, i);
+}
+
+/*
+ * Verify that digest lists are prefetched when requested, in the correct order
+ * (asynchronous version).
+ */
+TEST_F(shared_data, prefetch_async)
+{
+ if (self->no_kprobe)
+ SKIP(return, "CONFIG_DYNAMIC_FTRACE_WITH_ARGS not enabled");
+
+ prepare_prefetch(self, _metadata);
+
+ check_prefetch_list_async(self, _metadata);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/digest_cache/common.c b/tools/testing/selftests/digest_cache/common.c
new file mode 100644
index 000000000000..75c0ef50deb8
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Add common code for testing the Integrity Digest Cache.
+ */
+
+#include "common.h"
+
+const char *commands_str[DIGEST_CACHE__LAST] = {
+ [DIGEST_CACHE_GET] = "get",
+ [DIGEST_CACHE_LOOKUP] = "lookup",
+ [DIGEST_CACHE_PUT] = "put",
+ [DIGEST_CACHE_ENABLE_VERIF] = "enable_verif",
+ [DIGEST_CACHE_DISABLE_VERIF] = "disable_verif",
+ [DIGEST_CACHE_SET_VERIF] = "set_verif",
+ [DIGEST_CACHE_GET_PUT_ASYNC] = "get_put_async",
+};
+
+const char *const hash_algo_name[HASH_ALGO__LAST] = {
+ [HASH_ALGO_MD4] = "md4",
+ [HASH_ALGO_MD5] = "md5",
+ [HASH_ALGO_SHA1] = "sha1",
+ [HASH_ALGO_RIPE_MD_160] = "rmd160",
+ [HASH_ALGO_SHA256] = "sha256",
+ [HASH_ALGO_SHA384] = "sha384",
+ [HASH_ALGO_SHA512] = "sha512",
+ [HASH_ALGO_SHA224] = "sha224",
+ [HASH_ALGO_RIPE_MD_128] = "rmd128",
+ [HASH_ALGO_RIPE_MD_256] = "rmd256",
+ [HASH_ALGO_RIPE_MD_320] = "rmd320",
+ [HASH_ALGO_WP_256] = "wp256",
+ [HASH_ALGO_WP_384] = "wp384",
+ [HASH_ALGO_WP_512] = "wp512",
+ [HASH_ALGO_TGR_128] = "tgr128",
+ [HASH_ALGO_TGR_160] = "tgr160",
+ [HASH_ALGO_TGR_192] = "tgr192",
+ [HASH_ALGO_SM3_256] = "sm3",
+ [HASH_ALGO_STREEBOG_256] = "streebog256",
+ [HASH_ALGO_STREEBOG_512] = "streebog512",
+ [HASH_ALGO_SHA3_256] = "sha3-256",
+ [HASH_ALGO_SHA3_384] = "sha3-384",
+ [HASH_ALGO_SHA3_512] = "sha3-512",
+};
+
+const int hash_digest_size[HASH_ALGO__LAST] = {
+ [HASH_ALGO_MD4] = MD5_DIGEST_SIZE,
+ [HASH_ALGO_MD5] = MD5_DIGEST_SIZE,
+ [HASH_ALGO_SHA1] = SHA1_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_160] = RMD160_DIGEST_SIZE,
+ [HASH_ALGO_SHA256] = SHA256_DIGEST_SIZE,
+ [HASH_ALGO_SHA384] = SHA384_DIGEST_SIZE,
+ [HASH_ALGO_SHA512] = SHA512_DIGEST_SIZE,
+ [HASH_ALGO_SHA224] = SHA224_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_128] = RMD128_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_256] = RMD256_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_320] = RMD320_DIGEST_SIZE,
+ [HASH_ALGO_WP_256] = WP256_DIGEST_SIZE,
+ [HASH_ALGO_WP_384] = WP384_DIGEST_SIZE,
+ [HASH_ALGO_WP_512] = WP512_DIGEST_SIZE,
+ [HASH_ALGO_TGR_128] = TGR128_DIGEST_SIZE,
+ [HASH_ALGO_TGR_160] = TGR160_DIGEST_SIZE,
+ [HASH_ALGO_TGR_192] = TGR192_DIGEST_SIZE,
+ [HASH_ALGO_SM3_256] = SM3256_DIGEST_SIZE,
+ [HASH_ALGO_STREEBOG_256] = STREEBOG256_DIGEST_SIZE,
+ [HASH_ALGO_STREEBOG_512] = STREEBOG512_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_256] = SHA3_256_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_384] = SHA3_384_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_512] = SHA3_512_DIGEST_SIZE,
+};
+
+const char *verifs_str[] = {
+ [VERIF_FILENAMES] = "kprobe_filenames",
+ [VERIF_NUMBER] = "kprobe_number",
+ [VERIF_PREFETCH] = "kprobe_prefetch",
+};
diff --git a/tools/testing/selftests/digest_cache/common.h b/tools/testing/selftests/digest_cache/common.h
new file mode 100644
index 000000000000..3fd3c249ff6f
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header of common.c.
+ */
+
+#ifndef _COMMON_H
+#define _COMMON_H
+#include <linux/types.h>
+
+#include "../../../../include/uapi/linux/hash_info.h"
+
+#define MD5_DIGEST_SIZE 16
+#define SHA1_DIGEST_SIZE 20
+#define RMD160_DIGEST_SIZE 20
+#define SHA256_DIGEST_SIZE 32
+#define SHA384_DIGEST_SIZE 48
+#define SHA512_DIGEST_SIZE 64
+#define SHA224_DIGEST_SIZE 28
+#define RMD128_DIGEST_SIZE 16
+#define RMD256_DIGEST_SIZE 32
+#define RMD320_DIGEST_SIZE 40
+#define WP256_DIGEST_SIZE 32
+#define WP384_DIGEST_SIZE 48
+#define WP512_DIGEST_SIZE 64
+#define TGR128_DIGEST_SIZE 16
+#define TGR160_DIGEST_SIZE 20
+#define TGR192_DIGEST_SIZE 24
+#define SM3256_DIGEST_SIZE 32
+#define STREEBOG256_DIGEST_SIZE 32
+#define STREEBOG512_DIGEST_SIZE 64
+#define SHA3_224_DIGEST_SIZE (224 / 8)
+#define SHA3_256_DIGEST_SIZE (256 / 8)
+#define SHA3_384_DIGEST_SIZE (384 / 8)
+#define SHA3_512_DIGEST_SIZE (512 / 8)
+
+#define DIGEST_CACHE_DIR "/sys/kernel/security/integrity/digest_cache"
+#define DIGEST_CACHE_TEST_INTERFACE "/sys/kernel/security/digest_cache_test"
+#define DIGEST_CACHE_PATH_INTERFACE DIGEST_CACHE_DIR "/default_path"
+#define MAX_DIGEST_SIZE 64
+
+#define MAX_WORKS 21
+
+typedef __u8 u8;
+typedef __u16 u16;
+typedef __u32 u32;
+typedef __s32 s32;
+typedef __u64 u64;
+
+enum commands {
+ DIGEST_CACHE_GET, // args: <path>
+ DIGEST_CACHE_LOOKUP, // args: <algo>|<digest>
+ DIGEST_CACHE_PUT, // args:
+ DIGEST_CACHE_ENABLE_VERIF, // args: <verif name>
+ DIGEST_CACHE_DISABLE_VERIF, // args: <verif name>
+ DIGEST_CACHE_SET_VERIF, // args: <verif name>
+ DIGEST_CACHE_GET_PUT_ASYNC, // args: <path>|<start#>|<end#>
+ DIGEST_CACHE__LAST,
+};
+
+enum tlv_failures { TLV_NO_FAILURE,
+ TLV_FAILURE_ALGO_LEN,
+ TLV_FAILURE_ALGO_MISMATCH,
+ TLV_FAILURE_NUM_DIGESTS,
+ TLV_FAILURE__LAST
+};
+
+enum file_changes { FILE_WRITE,
+ FILE_TRUNCATE,
+ FILE_FTRUNCATE,
+ FILE_UNLINK,
+ FILE_RENAME,
+ FILE_SETXATTR,
+ FILE_REMOVEXATTR,
+ FILE_CHANGE__LAST
+};
+
+enum VERIFS {
+ VERIF_FILENAMES,
+ VERIF_NUMBER,
+ VERIF_PREFETCH,
+ VERIF__LAST
+};
+
+extern const char *commands_str[DIGEST_CACHE__LAST];
+extern const char *const hash_algo_name[HASH_ALGO__LAST];
+extern const int hash_digest_size[HASH_ALGO__LAST];
+extern const char *verifs_str[VERIF__LAST];
+
+#endif /* _COMMON_H */
diff --git a/tools/testing/selftests/digest_cache/common_user.c b/tools/testing/selftests/digest_cache/common_user.c
new file mode 100644
index 000000000000..02f661b942f7
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common_user.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Add common code in user space for testing the Integrity Digest Cache.
+ */
+
+#include <stddef.h>
+
+#include "common_user.h"
+
+static const char hex_asc[] = "0123456789abcdef";
+
+#define hex_asc_lo(x) hex_asc[((x) & 0x0f)]
+#define hex_asc_hi(x) hex_asc[((x) & 0xf0) >> 4]
+
+static inline char *hex_byte_pack(char *buf, unsigned char byte)
+{
+ *buf++ = hex_asc_hi(byte);
+ *buf++ = hex_asc_lo(byte);
+ return buf;
+}
+
+char *bin2hex(char *dst, const void *src, size_t count)
+{
+ const unsigned char *_src = src;
+
+ while (count--)
+ dst = hex_byte_pack(dst, *_src++);
+ return dst;
+}
diff --git a/tools/testing/selftests/digest_cache/common_user.h b/tools/testing/selftests/digest_cache/common_user.h
new file mode 100644
index 000000000000..8d1f6631ef83
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common_user.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header of common_user.c.
+ */
+
+#include <linux/types.h>
+#include <stddef.h>
+
+#include "common.h"
+
+char *bin2hex(char *dst, const void *src, size_t count);
diff --git a/tools/testing/selftests/digest_cache/config b/tools/testing/selftests/digest_cache/config
new file mode 100644
index 000000000000..7e0ea7d18828
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/config
@@ -0,0 +1,2 @@
+CONFIG_INTEGRITY_DIGEST_CACHE=y
+CONFIG_DYNAMIC_FTRACE=y
diff --git a/tools/testing/selftests/digest_cache/generators.c b/tools/testing/selftests/digest_cache/generators.c
new file mode 100644
index 000000000000..8c36c22e8bcc
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/generators.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Generate digest lists for testing.
+ */
+
+#include <stddef.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/xattr.h>
+#include <asm/byteorder.h>
+
+#include "generators.h"
+#include "../../../../include/uapi/linux/hash_info.h"
+#include "../../../../include/uapi/linux/xattr.h"
+#include "../../../../include/uapi/linux/tlv_digest_list.h"
+#include "../../../../include/uapi/linux/tlv_parser.h"
+
+int gen_tlv_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ enum tlv_failures failure)
+{
+ __u16 _algo = __cpu_to_be16(algo);
+ __u32 _num_entries = __cpu_to_be32(num_digests);
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ int digest_len = hash_digest_size[algo];
+ int ret, fd, i;
+
+ struct tlv_entry algo_entry = {
+ .field = __cpu_to_be16(DIGEST_LIST_ALGO),
+ .length = __cpu_to_be32(sizeof(_algo)),
+ };
+
+ struct tlv_entry num_entries_entry = {
+ .field = __cpu_to_be16(DIGEST_LIST_NUM_ENTRIES),
+ .length = __cpu_to_be32(sizeof(_num_entries)),
+ };
+
+ struct tlv_entry entry_digest = {
+ .field = __cpu_to_be16(DIGEST_LIST_ENTRY_DIGEST),
+ .length = __cpu_to_be32(digest_len),
+ };
+
+ struct tlv_entry entry_entry = {
+ .field = __cpu_to_be16(DIGEST_LIST_ENTRY),
+ .length = __cpu_to_be32(sizeof(entry_digest) + digest_len),
+ };
+
+ switch (failure) {
+ case TLV_FAILURE_ALGO_LEN:
+ algo_entry.length = algo_entry.length / 2;
+ break;
+ case TLV_FAILURE_ALGO_MISMATCH:
+ _algo = __cpu_to_be16(algo - 1);
+ break;
+ case TLV_FAILURE_NUM_DIGESTS:
+ num_digests = 0;
+ break;
+ default:
+ break;
+ }
+
+ fd = openat(temp_dirfd, digest_list_filename,
+ O_WRONLY | O_CREAT | O_TRUNC, 0600);
+ if (fd == -1)
+ return -errno;
+
+ ret = write(fd, (u8 *)&algo_entry, sizeof(algo_entry));
+ if (ret != sizeof(algo_entry))
+ return -errno;
+
+ ret = write(fd, (u8 *)&_algo, sizeof(_algo));
+ if (ret != sizeof(_algo))
+ return -errno;
+
+ ret = write(fd, (u8 *)&num_entries_entry, sizeof(num_entries_entry));
+ if (ret != sizeof(num_entries_entry))
+ return -errno;
+
+ ret = write(fd, (u8 *)&_num_entries, sizeof(_num_entries));
+ if (ret != sizeof(_num_entries))
+ return -errno;
+
+ *(u32 *)digest = start_number;
+
+ for (i = 0; i < num_digests; i++) {
+ ret = write(fd, (u8 *)&entry_entry, sizeof(entry_entry));
+ if (ret != sizeof(entry_entry))
+ return -errno;
+
+ ret = write(fd, (u8 *)&entry_digest, sizeof(entry_digest));
+ if (ret != sizeof(entry_digest))
+ return -errno;
+
+ ret = write(fd, digest, digest_len);
+ if (ret != digest_len)
+ return -errno;
+
+ (*(u32 *)digest)++;
+ }
+
+ close(fd);
+ return 0;
+}
+
+int create_file(int temp_dirfd, char *filename, char *digest_list_filename)
+{
+ int ret = 0, fd;
+
+ fd = openat(temp_dirfd, filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+ if (fd == -1)
+ return -errno;
+
+ if (!digest_list_filename)
+ goto out;
+
+ ret = fsetxattr(fd, XATTR_NAME_DIGEST_LIST, digest_list_filename,
+ strlen(digest_list_filename) + 1, 0);
+ if (ret == -1)
+ ret = -errno;
+out:
+ close(fd);
+ return ret;
+}
diff --git a/tools/testing/selftests/digest_cache/generators.h b/tools/testing/selftests/digest_cache/generators.h
new file mode 100644
index 000000000000..eeeb3c020891
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/generators.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header of generators.c.
+ */
+
+#include "common.h"
+#include "common_user.h"
+
+int gen_tlv_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ enum tlv_failures failure);
+int create_file(int temp_dirfd, char *filename, char *digest_list_filename);
diff --git a/tools/testing/selftests/digest_cache/testmod/Makefile b/tools/testing/selftests/digest_cache/testmod/Makefile
new file mode 100644
index 000000000000..1ba1c7f08658
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/testmod/Makefile
@@ -0,0 +1,16 @@
+KDIR ?= ../../../../..
+
+MODULES = digest_cache_kern.ko
+
+obj-m += digest_cache_kern.o
+
+digest_cache_kern-y := kern.o ../common.o
+
+all:
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD modules
+
+clean:
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD clean
+
+install: all
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD modules_install
diff --git a/tools/testing/selftests/digest_cache/testmod/kern.c b/tools/testing/selftests/digest_cache/testmod/kern.c
new file mode 100644
index 000000000000..4c215fd0b50f
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/testmod/kern.c
@@ -0,0 +1,551 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the kernel module to interact with the Integrity Digest Cache.
+ */
+
+#define pr_fmt(fmt) "digest_cache TESTMOD: "fmt
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/dynamic_debug.h>
+#include <linux/digest_cache.h>
+#include <linux/kprobes.h>
+#include <linux/cpu.h>
+#include <linux/kernel_read_file.h>
+#include <crypto/hash_info.h>
+
+#include "../common.h"
+
+struct verif {
+ int (*update)(struct file *file);
+ ssize_t (*read)(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos);
+ bool enabled;
+};
+
+struct read_work {
+ struct work_struct work;
+ char *path_str;
+ int ret;
+};
+
+static struct dentry *test;
+static struct digest_cache *digest_cache, *found;
+static int cur_verif_index;
+static u8 prefetch_buf[4096];
+static struct read_work w[MAX_WORKS];
+
+static int filenames_update(struct file *file)
+{
+ char *filename = (char *)file->f_path.dentry->d_name.name;
+
+ return digest_cache_verif_set(file, verifs_str[VERIF_FILENAMES],
+ filename, strlen(filename) + 1);
+}
+
+static int number_update(struct file *file)
+{
+ const char *filename = file_dentry(file)->d_name.name;
+ size_t filename_len = strlen(filename);
+ u64 number = U64_MAX;
+ int ret;
+
+ while (filename_len) {
+ if (filename[filename_len - 1] < '0' ||
+ filename[filename_len - 1] > '9')
+ break;
+
+ filename_len--;
+ }
+
+ ret = kstrtoull(filename + filename_len, 10, &number);
+ if (ret < 0) {
+ pr_debug("Failed to convert filename %s into number\n",
+ file_dentry(file)->d_name.name);
+ return ret;
+ }
+
+ return digest_cache_verif_set(file, verifs_str[VERIF_NUMBER], &number,
+ sizeof(number));
+}
+
+static int prefetch_update(struct file *file)
+{
+ char *filename = (char *)file->f_path.dentry->d_name.name;
+ char *start_ptr = prefetch_buf, *end_ptr;
+ int ret;
+
+ ret = digest_cache_verif_set(file, "kprobe_test", "1", 1);
+ if (!ret) {
+ /* Don't include duplicates of requested digest lists. */
+ while ((end_ptr = strchrnul(start_ptr, ','))) {
+ if (end_ptr > start_ptr &&
+ !strncmp(start_ptr, filename, end_ptr - start_ptr))
+ return 0;
+
+ if (!*end_ptr)
+ break;
+
+ start_ptr = end_ptr + 1;
+ }
+ }
+
+ if (prefetch_buf[0])
+ strlcat(prefetch_buf, ",", sizeof(prefetch_buf));
+
+ strlcat(prefetch_buf, filename, sizeof(prefetch_buf));
+ return 0;
+}
+
+static ssize_t filenames_read(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ loff_t _ppos = 0;
+ char *filenames_list;
+
+ filenames_list = digest_cache_verif_get(found ?: digest_cache,
+ verifs_str[VERIF_FILENAMES]);
+ if (!filenames_list)
+ return -ENOENT;
+
+ return simple_read_from_buffer(buf, datalen, &_ppos, filenames_list,
+ strlen(filenames_list) + 1);
+}
+
+static ssize_t number_read(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos)
+{
+ loff_t _ppos = 0;
+ u64 *number;
+ char temp[20];
+ ssize_t len;
+
+ number = digest_cache_verif_get(found ?: digest_cache,
+ verifs_str[VERIF_NUMBER]);
+ if (!number)
+ return -ENOENT;
+
+ len = snprintf(temp, sizeof(temp), "%llu", *number);
+
+ return simple_read_from_buffer(buf, datalen, &_ppos, temp, len);
+}
+
+static ssize_t prefetch_read(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ loff_t _ppos = 0;
+ ssize_t ret;
+
+ ret = simple_read_from_buffer(buf, datalen, &_ppos, prefetch_buf,
+ strlen(prefetch_buf) + 1);
+ memset(prefetch_buf, 0, sizeof(prefetch_buf));
+ return ret;
+}
+
+static struct verif verifs_methods[] = {
+ [VERIF_FILENAMES] = { .update = filenames_update,
+ .read = filenames_read },
+ [VERIF_NUMBER] = { .update = number_update, .read = number_read },
+ [VERIF_PREFETCH] = { .update = prefetch_update, .read = prefetch_read },
+};
+
+static void digest_cache_get_put_work(struct work_struct *work)
+{
+ struct read_work *w = container_of(work, struct read_work, work);
+ struct digest_cache *digest_cache;
+ struct path path;
+ struct file *file;
+
+ w->ret = kern_path(w->path_str, 0, &path);
+ if (w->ret < 0)
+ return;
+
+ file = kernel_file_open(&path, O_RDONLY, current_cred());
+ if (IS_ERR(file)) {
+ path_put(&path);
+ return;
+ }
+
+ digest_cache = digest_cache_get(file);
+
+ fput(file);
+ path_put(&path);
+
+ if (!digest_cache) {
+ w->ret = -ENOENT;
+ return;
+ }
+
+ digest_cache_put(digest_cache);
+ w->ret = 0;
+}
+
+static int digest_cache_get_put_async(char *path_str, int start_number,
+ int end_number)
+{
+ int ret = 0, i;
+
+ cpus_read_lock();
+ for (i = start_number; i <= end_number; i++) {
+ w[i].path_str = kasprintf(GFP_KERNEL, "%s%u", path_str, i);
+ if (!w[i].path_str) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ INIT_WORK_ONSTACK(&w[i].work, digest_cache_get_put_work);
+ schedule_work_on(i % num_online_cpus(), &w[i].work);
+ }
+ cpus_read_unlock();
+
+ for (i = start_number; i <= end_number; i++) {
+ if (!w[i].path_str)
+ continue;
+
+ flush_work(&w[i].work);
+ destroy_work_on_stack(&w[i].work);
+ kfree(w[i].path_str);
+ w[i].path_str = NULL;
+ if (!ret)
+ ret = w[i].ret;
+ }
+
+ return ret;
+}
+
+static ssize_t write_request(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ char *data, *data_ptr, *cmd_str, *path_str, *algo_str, *digest_str;
+ char *verif_name_str, *start_number_str, *end_number_str;
+ u8 digest[64];
+ struct path path;
+ struct file *filp;
+ int ret, cmd, algo, verif_index, start_number, end_number;
+
+ data = memdup_user_nul(buf, datalen);
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ data_ptr = data;
+
+ cmd_str = strsep(&data_ptr, "|");
+ if (!cmd_str) {
+ pr_debug("No command\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ cmd = match_string(commands_str, DIGEST_CACHE__LAST, cmd_str);
+ if (cmd < 0) {
+ pr_err("Unknown command %s\n", cmd_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ switch (cmd) {
+ case DIGEST_CACHE_GET:
+ if (found) {
+ if (!IS_ERR(found))
+ digest_cache_put(found);
+
+ found = NULL;
+ }
+
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kern_path(path_str, 0, &path);
+ if (ret < 0) {
+ pr_debug("Cannot find file %s\n", path_str);
+ goto out;
+ }
+
+ if (digest_cache) {
+ pr_debug("Digest cache exists, doing a put\n");
+ digest_cache_put(digest_cache);
+ }
+
+ filp = kernel_file_open(&path, O_RDONLY, current_cred());
+ if (IS_ERR(filp)) {
+ pr_debug("Cannot open file %s\n", path_str);
+ path_put(&path);
+ goto out;
+ }
+
+ digest_cache = digest_cache_get(filp);
+ ret = digest_cache ? 0 : -ENOENT;
+ pr_debug("digest cache get %s, ret: %d\n", path_str, ret);
+ fput(filp);
+ path_put(&path);
+ break;
+ case DIGEST_CACHE_LOOKUP:
+ if (found) {
+ if (!IS_ERR(found))
+ digest_cache_put(found);
+
+ found = NULL;
+ }
+
+ if (!digest_cache) {
+ pr_debug("No digest cache\n");
+ ret = -ENOENT;
+ goto out;
+ }
+
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ algo_str = strsep(&data_ptr, ":");
+ digest_str = data_ptr;
+
+ if (!algo_str || !digest_str) {
+ pr_debug("No algo or digest\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ algo = match_string(hash_algo_name, HASH_ALGO__LAST, algo_str);
+ if (algo < 0) {
+ pr_err("Unknown algorithm %s", algo_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ ret = hex2bin(digest, digest_str, hash_digest_size[algo]);
+ if (ret < 0) {
+ pr_debug("Invalid digest %s\n", digest_str);
+ goto out;
+ }
+
+ ret = kern_path(path_str, 0, &path);
+ if (ret < 0) {
+ pr_debug("Cannot find file %s\n", path_str);
+ goto out;
+ }
+
+ ret = -ENOENT;
+
+ found = digest_cache_lookup(path.dentry, digest_cache, digest,
+ algo);
+ path_put(&path);
+ if (found && !IS_ERR(found))
+ ret = 0;
+
+ pr_debug("%s:%s lookup %s, ret: %d\n", algo_str, digest_str,
+ path_str, ret);
+ break;
+ case DIGEST_CACHE_PUT:
+ if (digest_cache) {
+ digest_cache_put(digest_cache);
+ digest_cache = NULL;
+ }
+
+ if (found) {
+ if (!IS_ERR(found))
+ digest_cache_put(found);
+
+ found = NULL;
+ }
+ ret = 0;
+ pr_debug("digest cache put, ret: %d\n", ret);
+ break;
+ case DIGEST_CACHE_ENABLE_VERIF:
+ case DIGEST_CACHE_DISABLE_VERIF:
+ if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+
+ memset(prefetch_buf, 0, sizeof(prefetch_buf));
+ fallthrough;
+ case DIGEST_CACHE_SET_VERIF:
+ verif_name_str = strsep(&data_ptr, "|");
+ if (!verif_name_str) {
+ pr_debug("No verifier name\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ verif_index = match_string(verifs_str, ARRAY_SIZE(verifs_str),
+ verif_name_str);
+ if (verif_index < 0) {
+ pr_err("Unknown verifier name %s\n", verif_name_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (cmd == DIGEST_CACHE_ENABLE_VERIF)
+ verifs_methods[verif_index].enabled = true;
+ else if (cmd == DIGEST_CACHE_DISABLE_VERIF)
+ verifs_methods[verif_index].enabled = false;
+ else
+ cur_verif_index = verif_index;
+
+ ret = 0;
+ pr_debug("digest cache %s %s, ret: %d\n", cmd_str,
+ verif_name_str, ret);
+ break;
+ case DIGEST_CACHE_GET_PUT_ASYNC:
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ start_number_str = strsep(&data_ptr, "|");
+ if (!start_number_str) {
+ pr_debug("No start number\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kstrtoint(start_number_str, 10, &start_number);
+ if (ret < 0) {
+ pr_debug("Invalid start number %s\n", start_number_str);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ end_number_str = strsep(&data_ptr, "|");
+ if (!end_number_str) {
+ pr_debug("No end number\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kstrtoint(end_number_str, 10, &end_number);
+ if (ret < 0) {
+ pr_debug("Invalid end number %s\n", end_number_str);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (end_number - start_number >= MAX_WORKS) {
+ pr_debug("Too many works (%d), max %d\n",
+ end_number - start_number, MAX_WORKS - 1);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = digest_cache_get_put_async(path_str, start_number,
+ end_number);
+ pr_debug("digest cache %s on %s, start: %d, end: %d, ret: %d\n",
+ cmd_str, path_str, start_number, end_number, ret);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+out:
+ kfree(data);
+ return ret ?: datalen;
+}
+
+static ssize_t read_request(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos)
+{
+ return verifs_methods[cur_verif_index].read(file, buf, datalen, ppos);
+}
+
+static const struct file_operations digest_cache_test_ops = {
+ .open = generic_file_open,
+ .write = write_request,
+ .read = read_request,
+ .llseek = generic_file_llseek,
+};
+
+static int __kprobes kernel_post_read_file_hook(struct kprobe *p,
+ struct pt_regs *regs)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
+ struct file *file = (struct file *)regs_get_kernel_argument(regs, 0);
+ enum kernel_read_file_id id = regs_get_kernel_argument(regs, 3);
+#else
+ struct file *file = NULL;
+ enum kernel_read_file_id id = READING_UNKNOWN;
+#endif
+ int ret, i;
+
+ if (id != READING_DIGEST_LIST)
+ return 0;
+
+ for (i = 0; i < ARRAY_SIZE(verifs_methods); i++) {
+ if (!verifs_methods[i].enabled)
+ continue;
+
+ ret = verifs_methods[i].update(file);
+ if (ret < 0)
+ return 0;
+ }
+
+ return 0;
+}
+
+static struct kprobe kp = {
+ .symbol_name = "security_kernel_post_read_file",
+};
+
+static int __init digest_cache_test_init(void)
+{
+ int ret;
+
+ kp.pre_handler = kernel_post_read_file_hook;
+
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) {
+ ret = register_kprobe(&kp);
+ if (ret < 0) {
+ pr_err("register_kprobe failed, returned %d\n", ret);
+ return ret;
+ }
+ }
+
+ test = securityfs_create_file("digest_cache_test", 0660, NULL, NULL,
+ &digest_cache_test_ops);
+ if (IS_ERR(test)) {
+ ret = PTR_ERR(test);
+ goto out_kprobe;
+ }
+
+ return 0;
+out_kprobe:
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
+ unregister_kprobe(&kp);
+ return ret;
+}
+
+static void __exit digest_cache_test_fini(void)
+{
+ if (digest_cache)
+ digest_cache_put(digest_cache);
+
+ if (found) {
+ if (!IS_ERR(found))
+ digest_cache_put(found);
+
+ found = NULL;
+ }
+
+ securityfs_remove(test);
+ if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS))
+ unregister_kprobe(&kp);
+ pr_debug("kprobe at %p unregistered\n", kp.addr);
+}
+
+module_init(digest_cache_test_init);
+module_exit(digest_cache_test_fini);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Kernel module for testing Integrity Digest Cache");
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 15/15] docs: Add documentation of the Integrity Digest Cache
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add the documentation of the Integrity Digest Cache in
Documentation/security.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
Documentation/security/digest_cache.rst | 850 ++++++++++++++++++++++++
Documentation/security/index.rst | 1 +
MAINTAINERS | 2 +
3 files changed, 853 insertions(+)
create mode 100644 Documentation/security/digest_cache.rst
diff --git a/Documentation/security/digest_cache.rst b/Documentation/security/digest_cache.rst
new file mode 100644
index 000000000000..54392fd2d3b3
--- /dev/null
+++ b/Documentation/security/digest_cache.rst
@@ -0,0 +1,850 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+Integrity Digest Cache
+======================
+
+Introduction
+============
+
+Integrity detection and protection has long been a desirable feature, to
+reach a large user base and mitigate the risk of flaws in the software
+and attacks.
+
+However, while solutions exist, they struggle to reach a large user base,
+due to requiring higher than desired constraints on performance,
+flexibility and configurability, that only security conscious people are
+willing to accept.
+
+For example, IMA measurement requires the target platform to collect
+integrity measurements, and to protect them with the TPM, which introduces
+a noticeable overhead (up to 10x slower in a microbenchmark) on frequently
+used system calls, like the open().
+
+IMA Appraisal currently requires individual files to be signed and
+verified, and Linux distributions to rebuild all packages to include file
+signatures (this approach has been adopted from Fedora 39+). Like a TPM,
+also signature verification introduces a significant overhead, especially
+if it is used to check the integrity of many files.
+
+This is where the new Integrity Digest Cache comes into play, it offers
+additional support for new and existing integrity solutions, to make
+them faster and easier to deploy.
+
+The Integrity Digest Cache can help IMA to reduce the number of TPM
+operations and to make them happen in a deterministic way. If IMA knows
+that a file comes from a Linux distribution, it can measure files in a
+different way: measure the list of digests coming from the distribution
+(e.g. RPM package headers), and subsequently measure a file if it is not
+found in that list.
+
+The performance improvement comes at the cost of IMA not reporting which
+files from installed packages were accessed, and in which temporal
+sequence. This approach might not be suitable for all use cases.
+
+The Integrity Digest Cache can also help IMA for appraisal. IMA can simply
+lookup the calculated digest of an accessed file in the list of digests
+extracted from package headers, after verifying the header signature. It is
+sufficient to verify only one signature for all files in the package, as
+opposed to verifying a signature for each file.
+
+The same approach can be followed by other LSMs, such as Integrity Policy
+Enforcement (IPE), and BPF LSM.
+
+The Integrity Digest Cache is not tied to a specific package format. The
+kernel supports a TLV-based digest list format. More can be added through
+third-party kernel modules. The TLV parser has been verified for memory
+safety with the Frama-C static analyzer. The version with the Frama-C
+assertions is available here:
+
+https://github.com/robertosassu/rpm-formal/blob/main/validate_tlv.c
+
+Integrating the Integrity Digest Cache in IMA brings significant
+performance improvements: up to 67% and 79% for measurement respectively in
+sequential and parallel file reads; up to 65% and 43% for appraisal
+respectively in sequential and parallel file reads.
+
+The performance can be further enhanced by using fsverity digests instead
+of conventional file digests, which would make IMA verify only the portion
+of the file to be read. However, at the moment, fsverity digests are not
+included in RPM packages. In this case, once rpm is extended to include
+them, Linux distributions still have to rebuild their packages.
+
+The Integrity Digest Cache can support both digest types, so that the
+functionality is immediately available without waiting for Linux
+distributions to do the transition.
+
+
+Design
+======
+
+Main idea
+---------
+
+The Integrity Digest Cache extracts digests from a file, referred to as a
+digest list, and stores them in kernel memory in a structure named
+digest_cache.
+
+The digest_cache structure contains a set of per algorithm hash tables,
+where digests are stored, the digest list pathname, a reference counter,
+and the integrity state of the digest list.
+
+If a digest cache is created from a directory, its hash tables are empty
+and instead it contains a snapshot of the directory entries discovered with
+iterate_dir().
+
+The integrity state of digest caches created from regular files, also
+called verification data, is evaluated independently by LSMs, for example
+by verifying the signature of the digest list, and is provided to the
+Integrity Digest Cache through a dedicated API.
+
+The extracted digests can be used as reference values initially for
+integrity verification of file data and at a later stage for integrity
+verification of file metadata.
+
+The Integrity Digest Cache can extract digests from a digest list, provided
+that it has a parser for its format.
+
+
+Caching and reference counting
+------------------------------
+
+Creating a digest cache every time it is requested would introduce an
+unnecessary overhead, due to repeating the same operation. For this reason,
+the Integrity Digest Cache reserves space in the inode security blob
+(through IMA) and stores two types of digest cache reference.
+
+If the digest cache was created from the same inode, the Integrity Digest
+Cache stores in the inode security blob a reference called dig_owner,
+because the inode owns the content.
+
+If the digest cache was requested for verifying an inode, the Integrity
+Digest Cache stores a reference called dig_user, because the inode is a
+user of the digest cache.
+
+An inode can have both types of reference set, if it is a digest list
+to be verified with another digest list.
+
+Check and assignment of dig_owner and dig_user is protected respectively
+with the dig_owner_mutex and dig_user_mutex mutexes.
+
+The digest cache reference count tracks how many references have been made
+to that digest cache (whether that reference is stored in the inode
+security blob, or is returned to a user of the Integrity Digest Cache).
+
+Only when the reference count reaches zero, i.e. all references have been
+released, the digest cache can be freed.
+
+
+Digest cache lifecycle
+----------------------
+
+Digest cache request
+~~~~~~~~~~~~~~~~~~~~
+
+The first step in order to query a digest from a digest list is to request
+a digest cache, by calling digest_cache_get(). The Integrity Digest Cache
+takes care of the digest cache creation and initialization processes,
+transparently to the caller.
+
+The caller passes as argument to digest_cache_get() a file descriptor of
+the inode that the caller intends to verify. The Integrity Digest Cache
+first sees if there is a cached digest cache in that inode (dig_user
+reference). If there is, it immediately returns the digest cache with the
+reference count increased, since the reference is returned to the caller.
+
+Otherwise, it will perform the necessary steps (below) to obtain one.
+
+
+Digest list lookup
+~~~~~~~~~~~~~~~~~~
+
+In order to build a digest cache and return it to the caller for performing
+a query, the Integrity Digest Cache must know which digest list to use.
+There are a few alternatives.
+
+(1) There is only one digest list and its path is specified as default
+location at build-time in the kernel configuration or at run-time through
+securityfs. The Integrity Digest Cache builds a single digest cache from
+that digest list and returns it to the caller.
+
+(2) The default location is a directory containing multiple digest lists.
+Unlike (1), the Integrity Digest Cache does not know which digest list to
+select, and creates a directory digest cache with a snapshot of the
+directory entries. During a query, the Integrity Digest Cache iteratively
+creates a digest cache for each directory entry and searches for the digest
+until there is a match.
+
+(3) Same as (2), but the digest list file name is stored as value of the
+new security.digest_list xattr in the inode for which the digest cache is
+requested. The Integrity Digest Cache can directly retrieve the digest list
+using the default directory as the base path and the xattr value as last
+path component.
+
+(4) Similar to (3), but the Integrity Digest Cache still creates a
+directory digest cache like in (2). Then, it only reads the digest list if
+the directory entry file name does not match the security.digest_list
+xattr, to trigger a measurement or, otherwise, creates a digest cache from
+the matching one. This is also known as the prefetching mechanism,
+introduced later.
+
+
+Digest cache creation
+~~~~~~~~~~~~~~~~~~~~~
+
+Once the Integrity Digest Cache selected the digest list to use, it looks
+up the digest list inode through the VFS, verifies whether in the inode
+security blob there is already a digest cache reference (dig_owner).
+
+If there is, it returns that to digest_cache_get() with the reference count
+increased, which in turn will store it in dig_user and will increment the
+reference count again before returning to the caller.
+
+If there isn't, it creates a new digest cache and performs the same steps
+as if dig_owner exists.
+
+
+Digest cache initialization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The digest cache creation does not include initialization and adding the
+digests. It cannot be done inside the dig_owner_mutex and dig_user_mutex,
+to avoid lock inversion with the inode lock done by the VFS.
+
+Digest cache initialization is done by digest_cache_get() by
+calling digest_cache_init(), after releasing the dig_user_mutex. Any
+digest_cache_get() caller can potentially initialize a digest cache.
+
+To avoid multiple initialization attempts, callers that got the path of the
+digest lists atomically test and set the INIT_STARTED atomic flag. The
+first seeing the flag cleared is the one in charge of the initialization.
+The other callers wait for another atomic flag, INIT_IN_PROGRESS to be
+cleared to zero (it is set to one on digest cache creation).
+
+Failures during initialization can be detected by checking the INVALID flag
+in the digest cache and, in this case, the digest cache is not returned to
+the caller of digest_cache_get().
+
+
+Digest list naming convention
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The digest_cache_get() caller performing the digest cache initialization
+reads the digest list and calls the appropriate parser to extract the
+digests, based on the file name prefix.
+
+The expected digest list file name format is::
+
+ <digest list format>-<digest list name>
+
+where format can be for example ``tlv``, which makes the Integrity Digest
+Cache call the TLV parser.
+
+Alternatively, also the following format is supported::
+
+ <seq num>-<digest list format>-<digest list name>
+
+``<seq num>-`` defines how directory entries should be ordered in the
+directory digest cache. If present, directory entries are ordered in
+ascending way by that number.
+
+
+Digest list parsers
+^^^^^^^^^^^^^^^^^^^
+
+The Integrity Digest Cache supports an arbitrary number of parsers. New
+parsers can be added through third-party kernel modules, which should
+register a new parser name and function through the Parser API.
+
+The Integrity Digest Cache expects kernel modules containing the parsers to
+be placed in
+``/lib/modules/<kernel ver>/kernel/security/integrity/digest_cache``. If it
+does not find the required parser, it attempts to load a kernel module with
+the digest list format as file name, plus the .ko suffix and the
+appropriate compression suffix obtained from the kernel configuration.
+
+The Integrity Digest Cache loads kernel modules with parsers from the
+kernel itself by calling the new function ksys_finit_module(). This
+solution is necessary because, if the kernel module loading is demanded to
+user space, there might not be yet a digest cache required to verify the
+user space code.
+
+Currently, the kernel only provides a TLV-based digest list format. The RPM
+parser can be found in the digest-cache-tools software.
+
+
+Digest list parsing
+^^^^^^^^^^^^^^^^^^^
+
+The selected digest list parser first calls digest_cache_htable_init() to
+create the hash tables in the digest cache, once for each hash algorithm
+of the digests to be added. digest_cache_htable_init() accepts as parameter
+the number of digests to add, usually known before adding digests.
+
+The number of hash table slots is determined by dividing the number of
+digests to add by the desired average collision depth. The latter can be
+changed in the kernel configuration, to have a different tradeoff between
+digest lookup speed and memory occupation.
+
+The parser then calls digest_cache_htable_add(), to add extracted digests
+to the new hash tables. It can also call digest_cache_htable_lookup() to
+check for duplicate digests.
+
+
+Directory digest cache
+^^^^^^^^^^^^^^^^^^^^^^
+
+If the digest list location is a directory, digest_cache_init() calls
+digest_cache_dir_add_entries(), which in turn calls iterate_dir() to
+get the current directory entries and to add them to a linked list.
+
+When a digest is looked up on a directory digest cache,
+digest_cache_dir_lookup_digest() will create a regular digest cache for
+each directory entry and will lookup into it until it finds the digest.
+
+digest_cache_dir_lookup_digest() also gets a digest cache reference for
+each directory entry, so that digest lookup is faster at the next call.
+
+
+Digest lookup
+~~~~~~~~~~~~~
+
+After a caller of digest_cache_get() obtains the desired digest cache, it
+can perform operations on it. The most important operation is querying for
+a digest, which can be performed by calling digest_cache_lookup().
+
+digest_cache_lookup() returns a reference of the digest cache containing
+the queried digest, that must be freed by calling digest_cache_put().
+
+If digest_cache_get() returned a directory digest cache,
+digest_cache_lookup() cannot directly perform the search, since its hash
+tables are empty. Instead, it calls digest_cache_dir_lookup_digest(),
+which searches the digest in the digest cache of each directory entry.
+
+Between digest_cache_get() and digest_cache_lookup() there is still the
+possibility that a concurrent VFS operation affects the digest cache
+returned by digest_cache_get(). If that happened, digest_cache_lookup()
+returns an error pointer to the caller, which in turn should call
+digest_cache_get() and digest_cache_lookup() again.
+
+
+
+Verification data
+~~~~~~~~~~~~~~~~~
+
+Until now, the caller of the Integrity Digest Cache is assumed to always
+trust the returned digest cache from being created from authentic data. Or,
+there are security measures in place but not able to correlate reading a
+digest list with building a digest cache from it.
+
+The Integrity Digest Cache introduces a new mechanism for integrity
+providers to store verification data, i.e. their evaluation result of a
+digest list. It also allows callers of digest_cache_get() to later retrieve
+that information and decide whether or not they should use that digest
+cache.
+
+It achieves that by reserving space in the file descriptor security blob,
+and by setting the digest cache pointer in the digest list file descriptor
+before the digest list is read by the kernel.
+
+Integrity providers should implement the kernel_post_read_file LSM hook and
+call digest_cache_verif_set(), passing the same digest list file descriptor
+on which the digest cache pointer was set, their unique ID and their
+evaluation result of the digest list.
+
+The Integrity Digest Cache supports multiple integrity providers at the
+same time, since multiple LSMs can implement the kernel_post_read_file LSM
+hook. Each provider is expected to choose an unique ID, so that the
+verification data can be given back through the same ID.
+
+Callers of digest_cache_get() can call digest_cache_verif_get() to get
+the verification data, passing the returned digest cache pointer and the
+desired integrity provider ID. However, if the digest cache returned was
+created from a directory, that call results in a NULL pointer, since the
+directory digest cache is not populated from any digest list.
+
+In that case, those callers have to call digest_cache_lookup() to get the
+digest cache containing the digest (thus populated from a digest list), and
+pass it to digest_cache_verif_get().
+
+
+Tracking digest cache changes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+After a digest cache has been built and its pointer has been set in the
+inode security blob, it might happen that there are changes in the digest
+lists, in the default directory and in the value of the
+security.digest_list xattr.
+
+All these changes may influence which digest cache is returned to callers
+of digest_cache_get() and which digests in the digest cache might be
+searched.
+
+The Integrity Digest Cache monitors such changes by registering to multiple
+LSM hooks (path_truncate, file_release, inode_unlink, inode_rename,
+inode_post_setxattr and inode_post_removexattr). Except for the last two,
+it accesses the dig_owner pointer in the affected inode security blob, sets
+the RESET bit, puts the digest cache and clears dig_owner itself.
+
+The next time that digest cache is requested with digest_cache_get(), also
+dig_user is put and cleared. The same happens in
+digest_cache_dir_lookup_digest(), where the digest cache of a directory
+entry is released and cleared as well. After a reset, a new digest cache is
+created and returned, as if there wasn't one in the first place.
+
+For the last two hooks, when the security.digest_list xattr is modified,
+dig_user is cleared so that at the next digest_cache_get() call a new
+digest cache is retrieved, since the location of the digest list might have
+changed.
+
+Previous callers of digest_cache_get() can still keep the reset digest
+cache. However, digest_cache_lookup() will not perform a search on it, but
+instead will return an error pointer, forcing the caller to get a fresh
+digest cache.
+
+
+Security decision update after digest cache changes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+While new calls to digest_cache_get() result in a new digest cache to be
+returned, resetting the previous digest cache does not reflect in a reset
+of possibly cached security decisions by users of the Integrity Digest
+Cache.
+
+One possible way for those users to become aware of a digest cache change
+is to store the digest cache pointer they used for a security decision, to
+call digest_cache_get() again during a new file access and to compare the
+two pointers. The previous pointer remains valid until the digest cache
+is released.
+
+IMA stores the current digest cache pointer in its managed metadata. At
+every file access, it calls digest_cache_get() again and compares the
+returned pointer with the one previously stored. If the pointers are the
+same, IMA continues to use the previous evaluation result. If not, it
+performs the evaluation again.
+
+The cost of this check is very small. In the case where the digest cache
+didn't change since the last digest_cache_get(), the cost is to check if
+the dig_user pointer is not NULL, and to increment and decrement the digest
+cache reference count.
+
+In terms of memory, this solution requires IMA to store an additional
+pointer in its metadata.
+
+
+Nested IMA calls
+~~~~~~~~~~~~~~~~
+
+The Integrity Digest Cache internally opens kernel modules required to
+parse digest lists and the digest lists themselves. This causes IMA to be
+called again recursively, to verify those files. The problem is that
+digest_cache_get() is called with iint->mutex held. If the inode requested
+in the recursive call is the same as the one in the first call, the kernel
+would deadlock, because IMA would try to take an already locked mutex.
+
+Fortunately, this situation does not happen since the Integrity Digest
+Cache ensures that the two inodes will never be the same or otherwise it
+returns an error. Secondly, the Integrity Digest Cache offers the
+digest_cache_opened_fd() function to let the caller know whether or not the
+file descriptor passed as argument is managed by Integrity Digest Cache
+itself.
+
+If digest_cache_opened_fd() returns true, it is safe to nest IMA calls,
+without the risk of having deadlocks. mutex_lock() in process_measurement()
+is replaced with mutex_lock_nested() with the result of
+digest_cache_opened_fd() as second argument, so that lockdep does not emit
+a warning.
+
+
+Prefetching mechanism
+~~~~~~~~~~~~~~~~~~~~~
+
+One of the objectives of the Integrity Digest Cache is to make a TPM PCR
+predictable, by having digest lists measured in a deterministic order.
+Without the prefetching mechanism, digest lists are measured in a
+non-deterministic order, since the inodes for which a digest cache can be
+requested are accessed in a non-deterministic order too.
+
+The prefetching mechanism, when enabled by setting the new
+security.dig_prefetch xattr to 1, forces digest lists to be looked up by
+their file name in the digest cache created for the parent directory.
+
+The predictability of the PCR is ensured by reading both matching and
+non-matching digest lists during the search, so that integrity providers
+can measure them, and by only creating a digest cache for the matching one.
+In this way, it does not matter if a digest list later in the list of
+directory entries is requested before a earlier one, since all digest lists
+until that point are measured anyway.
+
+However, while this mechanism ensures predictability of the PCR, it could
+also introduce significant latencies, especially if the matching digest
+list is very late in the list of directory entries. Before a digest cache
+is returned from that digest list, hundreds or thousands of digest lists
+could have to be read first.
+
+Then, the ``[<seq num>-]`` prefix in the digest list file name comes at
+hand, since it determines the order of directory entries in the directory
+digest cache (entries with lower seq nums are before entries with higher
+seq nums). Digest lists without that prefix are added at the end of the
+directory entries list, in the same order as iterate_dir() shows them.
+
+Boot performance can be greatly improved by looking at the IMA measurement
+list and by seeing in which order digest lists are requested at boot. Then,
+``[<seq num>-]`` can be prepended to directory entries depending on their
+position in the measurement list.
+
+While digest lists can be requested in a slightly different order due to
+the non-deterministic access to inodes, the differences should be minimal,
+causing only fewer extra digest lists to be read before the right one is
+found.
+
+Ordering directory entries can also improve digest queries requiring
+iteration on all digest lists in the default directory. If directory
+entries are ordered by their appearance in the IMA measurement list, a
+digest is found faster because most likely it is searched in the same
+order as when the IMA measurement list was recorded, and thus its
+digest list comes earlier than the others in the list of the directory
+entries of the directory digest cache.
+
+
+Release a digest cache
+~~~~~~~~~~~~~~~~~~~~~~
+
+The Integrity Digest Cache uses the reference count mechanism to ensure
+that a digest cache does not simply disappear when someone is using it.
+
+Either when an inode is evicted from memory, or a caller of
+digest_cache_get() finished to use a digest cache, they should call
+digest_cache_put() to signal to the Integrity Digest Cache that they are no
+longer interested in that digest cache and that it can be eventually freed.
+
+A digest cache is freed when all digest cache users called
+digest_cache_put(), and the reference count reached the value zero.
+
+
+Formal verification of concurrency
+==================================
+
+The Integrity Digest Cache has been designed to work in a heavily concurrent
+environment, where code can be executed as a follow up of a VFS operation,
+or upon a direct request by a user of the Integrity Digest Cache.
+
+For this reason, a sound locking mechanism is necessary to protect data
+structures against concurrent accesses.
+
+The first verification of the locking mechanism was done with the in-kernel
+lockdep, which can detect potential deadlocks and unsafe usage of the
+locking primitives.
+
+There is an ongoing verification with a tool named Dartagnan, reachable at
+the following URL:
+
+https://github.com/hernanponcedeleon/Dat3M
+
+This verification required porting the Integrity Digest Cache to user
+space, and to simulate concurrent requests through the pthread library.
+
+Dartagnan explores all thread interleavings and checks for data races. In
+addition to lockdep, it can also spot for example improperly guarded
+variables.
+
+
+Data structures and API
+=======================
+
+Data structures
+---------------
+
+These are the data structures defined and used internally by the
+Integrity Digest Cache.
+
+.. kernel-doc:: security/integrity/digest_cache/internal.h
+
+
+Client API
+----------
+
+This API is meant to be used by users of the Integrity Digest Cache.
+
+.. kernel-doc:: security/integrity/digest_cache/main.c
+ :identifiers: digest_cache_get digest_cache_put
+ digest_cache_opened_fd
+
+.. kernel-doc:: security/integrity/digest_cache/htable.c
+ :identifiers: digest_cache_lookup
+
+.. kernel-doc:: security/integrity/digest_cache/verif.c
+ :identifiers: digest_cache_verif_set digest_cache_verif_get
+
+
+Parser API
+----------
+
+This API is meant to be used by digest list parsers.
+
+.. kernel-doc:: security/integrity/digest_cache/htable.c
+ :identifiers: digest_cache_htable_init
+ digest_cache_htable_add
+ digest_cache_htable_lookup
+
+.. kernel-doc:: security/integrity/digest_cache/parsers.c
+ :identifiers: digest_cache_register_parser
+ digest_cache_unregister_parser
+
+
+Digest list formats
+===================
+
+tlv
+---
+
+The Type-Length-Value (TLV) format was chosen for its extensibility.
+Additional fields can be added without breaking compatibility with old
+versions of the parser.
+
+The layout of a tlv digest list is the following::
+
+ [field: DIGEST_LIST_ALGO, length, value]
+ [field: DIGEST_LIST_NUM_ENTRIES, length, value]
+ [field: DIGEST_LIST_ENTRY#1, length, value (below)]
+ |- [DIGEST_LIST_ENTRY_DIGEST#1, length, file digest]
+ |- [DIGEST_LIST_ENTRY_PATH#1, length, file path]
+ [field: DIGEST_LIST_ENTRY#N, length, value (below)]
+ |- [DIGEST_LIST_ENTRY_DIGEST#N, length, file digest]
+ |- [DIGEST_LIST_ENTRY_PATH#N, length, file path]
+
+DIGEST_LIST_ALGO is a field to specify the algorithm of the file digest.
+DIGEST_LIST_NUM_ENTIES is a field to specify the number of
+DIGEST_LIST_ENTRY records. DIGEST_LIST_ENTRY is a nested TLV structure with
+the following fields: DIGEST_LIST_ENTRY_DIGEST contains the file digest;
+DIGEST_LIST_ENTRY_PATH contains the file path.
+
+
+Appended signature
+------------------
+
+Digest lists can have a module-style appended signature, that can be used
+for appraisal with IMA. The signature type can be PKCS#7, as for kernel
+modules, or a different type.
+
+
+History
+=======
+
+The original name of this work was IMA Digest Lists, which was somehow
+considered too invasive. The code was moved to a separate component named
+DIGLIM (DIGest Lists Integrity Module), with the purpose of removing the
+complexity away of IMA, and also adding the possibility of using it with
+other kernel components (e.g. Integrity Policy Enforcement, or IPE).
+
+The design changed significantly, so DIGLIM was renamed to Integrity Digest
+Cache, as the name better reflects what the new component does.
+
+Since it was originally proposed, in 2017, this work grew up a lot thanks
+to various comments/suggestions. It became integrally part of the openEuler
+distribution since end of 2020.
+
+The most important difference between the old the current version is moving
+from a centralized repository of file digests to a per-package repository.
+This reduces the digest lookup time, since digests are searched in smaller
+hash tables, and significantly reduces the memory pressure, since
+digest lists are loaded into kernel memory only when they are actually
+needed, and removed during reclamation.
+
+
+Performance
+===========
+
+System specification
+--------------------
+
+The tests have been performed on a Fedora 38 virtual machine with 4 cores
+(AMD EPYC-Rome, no hyperthreading), 16 GB of RAM, no TPM/TPM passthrough/
+emulated. The QEMU process has been pinned to 4 real CPU cores and its
+priority was set to -20.
+
+
+Benchmark tool
+--------------
+
+The Integrity Digest Cache has been tested with an ad-hoc benchmark tool
+that creates 20000 files with a random size up to 100 bytes and randomly
+adds their digest to one of 303 digest lists. The number of digest lists
+has been derived from the ratio (66) digests/packages (124174/1883) found
+in the testing virtual machine (hence, 20000/66 = 303). IMA signatures have
+been done with ECDSA NIST P-384.
+
+The benchmark tool then creates a list of 20000 files to be accessed,
+randomly chosen (there can be duplicates). This is necessary to make the
+results reproducible across reboots (by always replaying the same
+operations). The benchmark reads (sequentially and in parallel) the files
+from the list 2 times, flushing the kernel caches before each read.
+
+Each test has been performed 5 times, and the average value is taken.
+
+
+Purpose of the benchmark
+------------------------
+
+The purpose of the benchmark is to show the performance difference of IMA
+between the current behavior, and by using the Integrity Digest Cache.
+
+
+IMA measurement policy: no cache
+--------------------------------
+
+.. code-block:: bash
+
+ measure func=FILE_CHECK fowner=2001 pcr=12
+
+
+IMA measurement policy: cache
+-----------------------------
+
+.. code-block:: bash
+
+ measure func=DIGEST_LIST_CHECK pcr=12
+ measure func=FILE_CHECK fowner=2001 digest_cache=data pcr=12
+
+
+IMA measurement results
+-----------------------
+
+Sequential
+~~~~~~~~~~
+
+This test was performed reading files sequentially, and waiting for the
+current read to terminate before beginning a new one.
+
+::
+
+ +-------+------------------------+-----------+
+ | meas. | time no/p/vTPM (sec.) | slab (KB) |
+ +--------------------+-------+------------------------+-----------+
+ | no cache | 12313 | 31.71 / 102.80 / 46.29 | 86802 |
+ +--------------------+-------+------------------------+-----------+
+ | cache, no prefetch | 304 | 32.21 / 34.28 / 32.47 | 83709 |
+ +--------------------+-------+------------------------+-----------+
+ | cache, prefetch | 304 | 32.67 / 34.47 / 32.67 | 83720 |
+ +--------------------+-------+------------------------+-----------+
+
+The table shows that 12313 measurements (boot_aggregate + files) have been
+made without the digest cache, and 304 with the digest cache
+(boot_aggregate + digest lists). Consequently, the memory occupation
+without the cache is higher due to the higher number of measurements.
+
+Not surprisingly, for the same reason, also the test time is significantly
+higher without the digest cache when the physical or virtual TPM is used
+(with HMAC protection disabled).
+
+In terms of pure performance, first number in the third column, it can be
+seen that there are not significant performance differences between using
+or not using the digest cache.
+
+Prefetching adds little overhead, little because digest lists were ordered
+according to their appearance in the IMA measurement list (which minimizes
+the digest lists to prefetch).
+
+
+Parallel
+~~~~~~~~
+
+This test was performed reading files in parallel, not waiting for the
+current read to terminate.
+
+::
+
+ +-------+-----------------------+-----------+
+ | meas. | time no/p/vTPM (sec.) | slab (KB) |
+ +--------------------+-------+-----------------------+-----------+
+ | no cache | 12313 | 15.84 / 79.26 / 23.43 | 87635 |
+ +--------------------+-------+-----------------------+-----------+
+ | cache, no prefetch | 304 | 15.97 / 16.64 / 16.09 | 89890 |
+ +--------------------+-------+-----------------------+-----------+
+ | cache, prefetch | 304 | 16.18 / 16.84 / 16.24 | 85738 |
+ +--------------------+-------+-----------------------+-----------+
+
+Also in this case, the physical TPM causes the biggest delay especially
+without digest cache, where a higher number of measurements need to be
+extended in the TPM.
+
+The Integrity Digest Cache does not introduce a noticeable overhead in all
+scenarios.
+
+
+IMA appraisal policy: no cache
+------------------------------
+
+.. code-block:: bash
+
+ appraise func=FILE_CHECK fowner=2001
+
+
+IMA appraisal policy: cache
+---------------------------
+
+.. code-block:: bash
+
+ appraise func=DIGEST_LIST_CHECK
+ appraise func=FILE_CHECK fowner=2001 digest_cache=data
+
+
+IMA appraisal results
+---------------------
+
+Sequential
+~~~~~~~~~~
+
+This test was performed reading files sequentially, and waiting for the
+current read to terminate before beginning a new one.
+
+::
+
+ +-------------+-------------+-----------+
+ | files | time (sec.) | slab (KB) |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (ECDSA sig) | 12312 | 98.10 | 80842 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache) | 12312 + 303 | 34.09 | 83138 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache, prefetch) | 12312 + 303 | 34.08 | 83410 |
+ +----------------------------+-------------+-------------+-----------+
+
+This test shows a huge performance difference from verifying the signature
+of 12312 files as opposed to just verifying the signature of 303 digest
+lists, and looking up the digest of the files being read.
+
+There are some differences in terms of memory occupation, which is quite
+expected due to the fact that we have to take into account the digest
+caches loaded in memory, while with the standard appraisal they don't
+exist.
+
+
+Parallel
+~~~~~~~~
+
+This test was performed reading files in parallel, not waiting for the
+current read to terminate.
+
+::
+
+ +-------------+-------------+-----------+
+ | files | time (sec.) | slab (KB) |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (ECDSA sig) | 12312 | 29.00 | 82255 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache) | 12313 + 303 | 16.51 | 88359 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache, prefetch) | 12313 + 303 | 17.08 | 86266 |
+ +----------------------------+-------------+-------------+-----------+
+
+The difference is less marked when performing the read in parallel. Also,
+more memory seems to be occupied in the non-prefetch case.
+
+
+How to test
+===========
+
+Please follow the instructions here:
+
+https://github.com/linux-integrity/digest-cache-tools
diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst
index 3e0a7114a862..3c703cbf1cca 100644
--- a/Documentation/security/index.rst
+++ b/Documentation/security/index.rst
@@ -20,3 +20,4 @@ Security Documentation
landlock
secrets/index
ipe
+ digest_cache
diff --git a/MAINTAINERS b/MAINTAINERS
index 1f7ffa1c9dbd..cf749921120a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11279,8 +11279,10 @@ R: Eric Snowberg <eric.snowberg@oracle.com>
L: linux-integrity@vger.kernel.org
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
+F: Documentation/security/digest_cache.rst
F: security/integrity/
F: security/integrity/ima/
+F: tools/testing/selftests/digest_cache/
INTEGRITY POLICY ENFORCEMENT (IPE)
M: Fan Wu <wufan@linux.microsoft.com>
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* [PATCH v6 01/15] lib: Add TLV parser
From: Roberto Sassu @ 2024-11-19 10:49 UTC (permalink / raw)
To: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
From: Roberto Sassu <roberto.sassu@huawei.com>
Add a parser of a generic Type-Length-Value (TLV) format:
+--------------+--+---------+--------+---------+
| field1 (u16) | len1 (u32) | value1 (u8 len1) |
+--------------+------------+------------------+
| ... | ... | ... |
+--------------+------------+------------------+
| fieldN (u16) | lenN (u32) | valueN (u8 lenN) |
+--------------+------------+------------------+
Each adopter can define its own fields. The TLV parser does not need to be
aware of those, but lets the adopter obtain the data and decide how to
continue.
After processing a TLV entry, call the callback function also with the
callback data provided by the adopter. The latter can decide how to
interpret the TLV entry depending on the field ID.
Nesting TLVs is also possible, the callback function can call tlv_parse()
to parse the inner structure.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
MAINTAINERS | 8 +++
include/linux/tlv_parser.h | 32 ++++++++++++
include/uapi/linux/tlv_parser.h | 41 ++++++++++++++++
lib/Kconfig | 3 ++
lib/Makefile | 2 +
lib/tlv_parser.c | 87 +++++++++++++++++++++++++++++++++
lib/tlv_parser.h | 18 +++++++
7 files changed, 191 insertions(+)
create mode 100644 include/linux/tlv_parser.h
create mode 100644 include/uapi/linux/tlv_parser.h
create mode 100644 lib/tlv_parser.c
create mode 100644 lib/tlv_parser.h
diff --git a/MAINTAINERS b/MAINTAINERS
index a097afd76ded..1f7ffa1c9dbd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23388,6 +23388,14 @@ W: http://sourceforge.net/projects/tlan/
F: Documentation/networking/device_drivers/ethernet/ti/tlan.rst
F: drivers/net/ethernet/ti/tlan.*
+TLV PARSER
+M: Roberto Sassu <roberto.sassu@huawei.com>
+L: linux-kernel@vger.kernel.org
+S: Maintained
+F: include/linux/tlv_parser.h
+F: include/uapi/linux/tlv_parser.h
+F: lib/tlv_parser.*
+
TMIO/SDHI MMC DRIVER
M: Wolfram Sang <wsa+renesas@sang-engineering.com>
L: linux-mmc@vger.kernel.org
diff --git a/include/linux/tlv_parser.h b/include/linux/tlv_parser.h
new file mode 100644
index 000000000000..0c72742af548
--- /dev/null
+++ b/include/linux/tlv_parser.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LINUX_TLV_PARSER_H
+#define _LINUX_TLV_PARSER_H
+
+#include <uapi/linux/tlv_parser.h>
+
+/**
+ * typedef callback - Callback after parsing TLV entry
+ * @callback_data: Opaque data to supply to the callback function
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_len: Length of @field_data
+ *
+ * This callback is invoked after a TLV entry is parsed.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+typedef int (*callback)(void *callback_data, __u16 field,
+ const __u8 *field_data, __u32 field_len);
+
+int tlv_parse(callback callback, void *callback_data, const __u8 *data,
+ size_t data_len, const char **fields, __u32 num_fields);
+
+#endif /* _LINUX_TLV_PARSER_H */
diff --git a/include/uapi/linux/tlv_parser.h b/include/uapi/linux/tlv_parser.h
new file mode 100644
index 000000000000..171d0cfd2c4c
--- /dev/null
+++ b/include/uapi/linux/tlv_parser.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the user space interface for the TLV parser.
+ */
+
+#ifndef _UAPI_LINUX_TLV_PARSER_H
+#define _UAPI_LINUX_TLV_PARSER_H
+
+#include <linux/types.h>
+
+/*
+ * TLV format:
+ *
+ * +--------------+--+---------+--------+---------+
+ * | field1 (u16) | len1 (u32) | value1 (u8 len1) |
+ * +--------------+------------+------------------+
+ * | ... | ... | ... |
+ * +--------------+------------+------------------+
+ * | fieldN (u16) | lenN (u32) | valueN (u8 lenN) |
+ * +--------------+------------+------------------+
+ */
+
+/**
+ * struct tlv_entry - Entry of TLV format
+ * @field: Field identifier
+ * @length: Data length
+ * @data: Data
+ *
+ * This structure represents an entry of the TLV format.
+ */
+struct tlv_entry {
+ __u16 field;
+ __u32 length;
+ __u8 data[];
+} __attribute__((packed));
+
+#endif /* _UAPI_LINUX_TLV_PARSER_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index b38849af6f13..9141dcfc1704 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -777,3 +777,6 @@ config POLYNOMIAL
config FIRMWARE_TABLE
bool
+
+config TLV_PARSER
+ bool
diff --git a/lib/Makefile b/lib/Makefile
index 773adf88af41..630de494eab5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -393,5 +393,7 @@ obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
obj-$(CONFIG_FIRMWARE_TABLE) += fw_table.o
+obj-$(CONFIG_TLV_PARSER) += tlv_parser.o
+CFLAGS_tlv_parser.o += -I lib
subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify
diff --git a/lib/tlv_parser.c b/lib/tlv_parser.c
new file mode 100644
index 000000000000..dbbe08018b4d
--- /dev/null
+++ b/lib/tlv_parser.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Implement the TLV parser.
+ */
+
+#define pr_fmt(fmt) "tlv_parser: "fmt
+#include <tlv_parser.h>
+
+/**
+ * tlv_parse - Parse TLV data
+ * @callback: Callback function to call to parse the entries
+ * @callback_data: Opaque data to supply to the callback function
+ * @data: Data to parse
+ * @data_len: Length of @data
+ * @fields: Array of field strings
+ * @num_fields: Number of elements of @fields
+ *
+ * Parse the TLV data format and call the supplied callback function for each
+ * entry, passing also the opaque data pointer.
+ *
+ * The callback function decides how to process data depending on the field.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int tlv_parse(callback callback, void *callback_data, const __u8 *data,
+ size_t data_len, const char **fields, __u32 num_fields)
+{
+ const __u8 *data_ptr = data;
+ struct tlv_entry *entry;
+ __u16 parsed_field;
+ __u32 len;
+ int ret;
+
+ if (data_len > U32_MAX) {
+ pr_debug("Data too big, size: %zd\n", data_len);
+ return -E2BIG;
+ }
+
+ while (data_len) {
+ if (data_len < sizeof(*entry))
+ return -EBADMSG;
+
+ entry = (struct tlv_entry *)data_ptr;
+ data_ptr += sizeof(*entry);
+ data_len -= sizeof(*entry);
+
+ parsed_field = __be16_to_cpu(entry->field);
+ if (parsed_field >= num_fields) {
+ pr_debug("Invalid field %u, max: %u\n",
+ parsed_field, num_fields - 1);
+ return -EBADMSG;
+ }
+
+ len = __be32_to_cpu(entry->length);
+
+ if (data_len < len)
+ return -EBADMSG;
+
+ pr_debug("Data: field: %s, len: %u\n", fields[parsed_field],
+ len);
+
+ if (!len)
+ continue;
+
+ ret = callback(callback_data, parsed_field, data_ptr, len);
+ if (ret < 0) {
+ pr_debug("Parsing of field %s failed, ret: %d\n",
+ fields[parsed_field], ret);
+ return ret;
+ }
+
+ data_ptr += len;
+ data_len -= len;
+ }
+
+ if (data_len) {
+ pr_debug("Excess data: %zu bytes\n", data_len);
+ return -EBADMSG;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tlv_parse);
diff --git a/lib/tlv_parser.h b/lib/tlv_parser.h
new file mode 100644
index 000000000000..e663966deac5
--- /dev/null
+++ b/lib/tlv_parser.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <roberto.sassu@huawei.com>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LIB_TLV_PARSER_H
+#define _LIB_TLV_PARSER_H
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/limits.h>
+#include <linux/tlv_parser.h>
+
+#endif /* _LIB_TLV_PARSER_H */
--
2.47.0.118.gfd3785337b
^ permalink raw reply related
* Re: [PATCH v6 02/15] module: Introduce ksys_finit_module()
From: Christoph Hellwig @ 2024-11-19 12:14 UTC (permalink / raw)
To: Roberto Sassu
Cc: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue, linux-integrity, linux-doc,
linux-kernel, linux-api, linux-modules, linux-security-module,
linux-kselftest, wufan, pbrobinson, zbyszek, hch, mjg59, pmatilai,
jannh, dhowells, jikos, mkoutny, ppavlu, petr.vorel, mzerqung,
kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-3-roberto.sassu@huaweicloud.com>
On Tue, Nov 19, 2024 at 11:49:09AM +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Introduce ksys_finit_module() to let kernel components request a kernel
> module without requiring running modprobe.
That does sound more than sketchy, even more so because the commit log
completely fails to explain why you'd need to do that.
^ permalink raw reply
* Re: [PATCH v6 02/15] module: Introduce ksys_finit_module()
From: Roberto Sassu @ 2024-11-19 14:33 UTC (permalink / raw)
To: Christoph Hellwig
Cc: zohar, dmitry.kasatkin, eric.snowberg, corbet, mcgrof, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue, linux-integrity, linux-doc,
linux-kernel, linux-api, linux-modules, linux-security-module,
linux-kselftest, wufan, pbrobinson, zbyszek, mjg59, pmatilai,
jannh, dhowells, jikos, mkoutny, ppavlu, petr.vorel, mzerqung,
kgold, Roberto Sassu
In-Reply-To: <20241119121402.GA28228@lst.de>
On Tue, 2024-11-19 at 13:14 +0100, Christoph Hellwig wrote:
> On Tue, Nov 19, 2024 at 11:49:09AM +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> >
> > Introduce ksys_finit_module() to let kernel components request a kernel
> > module without requiring running modprobe.
>
> That does sound more than sketchy, even more so because the commit log
> completely fails to explain why you'd need to do that.
With my solution, the kernel grants access to a file in user space
depending on whether or not its calculated (or fsverity) digest is
found in an application manifest provided by the software vendor.
However, what it happens is that in the early boot phase the parser is
not loaded yet, and the kernel cannot extract the reference digests
from the application manifest.
Thus, calling request_module() and consequently executing modprobe will
fail, since the kernel does not have its reference digest yet.
Instead, loading the kernel module from the kernel itself works,
because only the kernel module needs to be verified, and that can be
done through its appended signature.
Roberto
^ permalink raw reply
* [PATCH] uapi: add EROBLK
From: Alexey Dobriyan @ 2024-11-19 15:54 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, linux-api
Block drivers and DM sometimes use EROFS to report errors. There is
no confusion about what happens but naive error reporting code might
pass -EROFS to strerror(3) which will print "filesystem" when clearly
there is no filesystem anywhere, it is layer above.
Or in other words, if EROFS exists, why not EROBLK?
It is not like there is a tax on errno values.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
include/uapi/asm-generic/errno.h | 1 +
1 file changed, 1 insertion(+)
--- a/include/uapi/asm-generic/errno.h
+++ b/include/uapi/asm-generic/errno.h
@@ -119,5 +119,6 @@
#define ERFKILL 132 /* Operation not possible due to RF-kill */
#define EHWPOISON 133 /* Memory page has hardware error */
+#define EROBLK 134 /* Block device is read-only */
#endif
^ permalink raw reply
* Re: [PATCH] uapi: add EROBLK
From: Christoph Hellwig @ 2024-11-19 16:22 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: Jens Axboe, linux-block, linux-api
In-Reply-To: <9184b5e8-7070-4395-b179-4975b2e3fbc3@p183>
On Tue, Nov 19, 2024 at 06:54:52PM +0300, Alexey Dobriyan wrote:
> Block drivers and DM sometimes use EROFS to report errors. There is
> no confusion about what happens but naive error reporting code might
> pass -EROFS to strerror(3) which will print "filesystem" when clearly
> there is no filesystem anywhere, it is layer above.
>
> Or in other words, if EROFS exists, why not EROBLK?
> It is not like there is a tax on errno values.
And where would you return this value without breaking existing
userspace?
^ permalink raw reply
* Re: [PATCH v6 07/15] digest_cache: Allow registration of digest list parsers
From: Randy Dunlap @ 2024-11-19 16:46 UTC (permalink / raw)
To: Roberto Sassu, zohar, dmitry.kasatkin, eric.snowberg, corbet,
mcgrof, petr.pavlu, samitolvanen, da.gomez, akpm, paul, jmorris,
serge, shuah, mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-8-roberto.sassu@huaweicloud.com>
Hi--
On 11/19/24 2:49 AM, Roberto Sassu wrote:
> +/**
> + * struct parser - Structure to store a function pointer to parse digest list
> + * @list: Linked list
> + * @owner: Kernel module owning the parser
> + * @name: Parser name (must match the format in the digest list file name)
> + * @func: Function pointer for parsing
> + *
> + * This structure stores a function pointer to parse a digest list.
> + */
> +struct parser {
> + struct list_head list;
> + struct module *owner;
> + const char name[NAME_MAX + 1];
> + parser_func func;
> +};
I would make the struct name not so generic -- maybe digest_parser ...
thanks.
--
~Randy
^ permalink raw reply
* Re: [PATCH v6 07/15] digest_cache: Allow registration of digest list parsers
From: Roberto Sassu @ 2024-11-19 16:48 UTC (permalink / raw)
To: Randy Dunlap, zohar, dmitry.kasatkin, eric.snowberg, corbet,
mcgrof, petr.pavlu, samitolvanen, da.gomez, akpm, paul, jmorris,
serge, shuah, mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <c6a7b5eb-d2ec-45e5-8a9b-a91f9c0cec78@infradead.org>
On Tue, 2024-11-19 at 08:46 -0800, Randy Dunlap wrote:
> Hi--
>
> On 11/19/24 2:49 AM, Roberto Sassu wrote:
> > +/**
> > + * struct parser - Structure to store a function pointer to parse digest list
> > + * @list: Linked list
> > + * @owner: Kernel module owning the parser
> > + * @name: Parser name (must match the format in the digest list file name)
> > + * @func: Function pointer for parsing
> > + *
> > + * This structure stores a function pointer to parse a digest list.
> > + */
> > +struct parser {
> > + struct list_head list;
> > + struct module *owner;
> > + const char name[NAME_MAX + 1];
> > + parser_func func;
> > +};
>
> I would make the struct name not so generic -- maybe digest_parser ...
Hi
sure, thanks for the suggestion!
Roberto
^ permalink raw reply
* Re: [PATCH v6 01/15] lib: Add TLV parser
From: Randy Dunlap @ 2024-11-19 16:51 UTC (permalink / raw)
To: Roberto Sassu, zohar, dmitry.kasatkin, eric.snowberg, corbet,
mcgrof, petr.pavlu, samitolvanen, da.gomez, akpm, paul, jmorris,
serge, shuah, mcoquelin.stm32, alexandre.torgue
Cc: linux-integrity, linux-doc, linux-kernel, linux-api,
linux-modules, linux-security-module, linux-kselftest, wufan,
pbrobinson, zbyszek, hch, mjg59, pmatilai, jannh, dhowells, jikos,
mkoutny, ppavlu, petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-2-roberto.sassu@huaweicloud.com>
Hi--
On 11/19/24 2:49 AM, Roberto Sassu wrote:
> +/**
> + * typedef callback - Callback after parsing TLV entry
Same as my other naming comment -- too generic.
Maybe tlv_callback...
Thanks.
> + * @callback_data: Opaque data to supply to the callback function
> + * @field: Field identifier
> + * @field_data: Field data
> + * @field_len: Length of @field_data
> + *
> + * This callback is invoked after a TLV entry is parsed.
> + *
> + * Return: Zero on success, a negative value on error.
> + */
> +typedef int (*callback)(void *callback_data, __u16 field,
> + const __u8 *field_data, __u32 field_len);
--
~Randy
^ permalink raw reply
* Re: [PATCH] uapi: add EROBLK
From: Alexey Dobriyan @ 2024-11-19 17:20 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Jens Axboe, linux-block, linux-api
In-Reply-To: <Zzy7MGyTp9yw1ntQ@infradead.org>
On Tue, Nov 19, 2024 at 08:22:08AM -0800, Christoph Hellwig wrote:
> On Tue, Nov 19, 2024 at 06:54:52PM +0300, Alexey Dobriyan wrote:
> > Block drivers and DM sometimes use EROFS to report errors. There is
> > no confusion about what happens but naive error reporting code might
> > pass -EROFS to strerror(3) which will print "filesystem" when clearly
> > there is no filesystem anywhere, it is layer above.
> >
> > Or in other words, if EROFS exists, why not EROBLK?
> > It is not like there is a tax on errno values.
>
> And where would you return this value without breaking existing
> userspace?
New code may start returning it right away.
Old code may start checking for both and in ~100 years delete EROFS
clause.
^ permalink raw reply
* Re: [PATCH] uapi: add EROBLK
From: Christoph Hellwig @ 2024-11-19 17:27 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: Christoph Hellwig, Jens Axboe, linux-block, linux-api
In-Reply-To: <dee8868f-45fa-40d7-bcaf-a46bf768e400@p183>
On Tue, Nov 19, 2024 at 08:20:33PM +0300, Alexey Dobriyan wrote:
> > And where would you return this value without breaking existing
> > userspace?
>
> New code may start returning it right away.
>
> Old code may start checking for both and in ~100 years delete EROFS
> clause.
In other word it's all hypothetical, you have no actual users in mind
and no ral problem to solve?
^ permalink raw reply
* Re: [PATCH v6 00/15] integrity: Introduce the Integrity Digest Cache
From: Luis Chamberlain @ 2024-11-19 20:03 UTC (permalink / raw)
To: Roberto Sassu
Cc: zohar, dmitry.kasatkin, eric.snowberg, corbet, petr.pavlu,
samitolvanen, da.gomez, akpm, paul, jmorris, serge, shuah,
mcoquelin.stm32, alexandre.torgue, linux-integrity, linux-doc,
linux-kernel, linux-api, linux-modules, linux-security-module,
linux-kselftest, wufan, pbrobinson, zbyszek, hch, mjg59, pmatilai,
jannh, dhowells, jikos, mkoutny, ppavlu, petr.vorel, mzerqung,
kgold, Roberto Sassu
In-Reply-To: <20241119104922.2772571-1-roberto.sassu@huaweicloud.com>
On Tue, Nov 19, 2024 at 11:49:07AM +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> v5:
> - Add new patch to introduce ksys_finit_module()
Why?
Luis
^ permalink raw reply
* Re: [PATCH v6 02/15] module: Introduce ksys_finit_module()
From: Luis Chamberlain @ 2024-11-19 20:10 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Roberto Sassu, zohar, dmitry.kasatkin, eric.snowberg, corbet,
petr.pavlu, samitolvanen, da.gomez, akpm, paul, jmorris, serge,
shuah, mcoquelin.stm32, alexandre.torgue, linux-integrity,
linux-doc, linux-kernel, linux-api, linux-modules,
linux-security-module, linux-kselftest, wufan, pbrobinson,
zbyszek, mjg59, pmatilai, jannh, dhowells, jikos, mkoutny, ppavlu,
petr.vorel, mzerqung, kgold, Roberto Sassu
In-Reply-To: <20241119121402.GA28228@lst.de>
On Tue, Nov 19, 2024 at 01:14:02PM +0100, Christoph Hellwig wrote:
> On Tue, Nov 19, 2024 at 11:49:09AM +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> >
> > Introduce ksys_finit_module() to let kernel components request a kernel
> > module without requiring running modprobe.
>
> That does sound more than sketchy, even more so because the commit log
> completely fails to explain why you'd need to do that.
I also don't think the commit log is correct, I don't see how the
code is preventing calling modprobe, the indepotent check is intended
to prevent duplicate module init calls which may allocate extra vmalloc
space only to release it. You can test to see if your patch has any
improvments by enabling MODULE_STATS and MODULE_DEBUG_AUTOLOAD_DUPS
and check before / after results of /sys/kernel/debug/modules/stats ,
right now this patch and commit log is not telling me anything useful.
Luis
^ permalink raw reply
* Re: [PATCH net-next v2 00/12] Begin upstreaming Homa transport protocol
From: John Ousterhout @ 2024-11-19 21:13 UTC (permalink / raw)
To: Cong Wang; +Cc: netdev, linux-api
In-Reply-To: <CAGXJAmyGTwjFo6fGoROY=hQFXbR5RdpmpkEc9Zm6DOoD2nbwNA@mail.gmail.com>
On Thu, Nov 14, 2024 at 8:59 AM John Ousterhout <ouster@cs.stanford.edu> wrote:
>
> On Wed, Nov 13, 2024 at 9:08 AM Cong Wang <xiyou.wangcong@gmail.com> wrote:
>
> > 2. Please consider adding socket diagnostics, see net/ipv4/inet_diag.c.
>
> I wasn't familiar with them before your email; I'll take a look.
I have taken a look at socket diagnostics, and I agree that Homa
should support them. However, this looks like a nontrivial task: there
appears to be a fair amount of complexity there, not much
documentation, and the current diagnostics appear pretty TCP-specific
so it may take some work (and advice) to figure out how to map them
onto Homa. Thus it feels like it will take a fair amount of
back-and-forth to get this right. I would prefer to defer this until
after the main body of Homa has been upstreamed, then have a patch
series that is dedicated to socket diagnostics support, rather than
lumping socket diagnostics into the current patch series. Is that OK
with you?
-John-
^ permalink raw reply
* Re: [PATCH v21 1/6] exec: Add a new AT_EXECVE_CHECK flag to execveat(2)
From: Jeff Xu @ 2024-11-20 1:17 UTC (permalink / raw)
To: Mickaël Salaün
Cc: Al Viro, Christian Brauner, Kees Cook, Paul Moore, Serge Hallyn,
Adhemerval Zanella Netto, Alejandro Colomar, Aleksa Sarai,
Andrew Morton, Andy Lutomirski, Arnd Bergmann, Casey Schaufler,
Christian Heimes, Dmitry Vyukov, Elliott Hughes, Eric Biggers,
Eric Chiang, Fan Wu, Florian Weimer, Geert Uytterhoeven,
James Morris, Jan Kara, Jann Horn, Jeff Xu, Jonathan Corbet,
Jordan R Abrahams, Lakshmi Ramasubramanian, Linus Torvalds,
Luca Boccassi, Luis Chamberlain, Madhavan T . Venkataraman,
Matt Bobrowski, Matthew Garrett, Matthew Wilcox, Miklos Szeredi,
Mimi Zohar, Nicolas Bouchinet, Scott Shell, Shuah Khan,
Stephen Rothwell, Steve Dower, Steve Grubb, Theodore Ts'o,
Thibaut Sautereau, Vincent Strubel, Xiaoming Ni, Yin Fengwei,
kernel-hardening, linux-api, linux-fsdevel, linux-integrity,
linux-kernel, linux-security-module
In-Reply-To: <20241112191858.162021-2-mic@digikod.net>
On Tue, Nov 12, 2024 at 11:22 AM Mickaël Salaün <mic@digikod.net> wrote:
>
> Add a new AT_EXECVE_CHECK flag to execveat(2) to check if a file would
> be allowed for execution. The main use case is for script interpreters
> and dynamic linkers to check execution permission according to the
> kernel's security policy. Another use case is to add context to access
> logs e.g., which script (instead of interpreter) accessed a file. As
> any executable code, scripts could also use this check [1].
>
> This is different from faccessat(2) + X_OK which only checks a subset of
> access rights (i.e. inode permission and mount options for regular
> files), but not the full context (e.g. all LSM access checks). The main
> use case for access(2) is for SUID processes to (partially) check access
> on behalf of their caller. The main use case for execveat(2) +
> AT_EXECVE_CHECK is to check if a script execution would be allowed,
> according to all the different restrictions in place. Because the use
> of AT_EXECVE_CHECK follows the exact kernel semantic as for a real
> execution, user space gets the same error codes.
>
> An interesting point of using execveat(2) instead of openat2(2) is that
> it decouples the check from the enforcement. Indeed, the security check
> can be logged (e.g. with audit) without blocking an execution
> environment not yet ready to enforce a strict security policy.
>
> LSMs can control or log execution requests with
> security_bprm_creds_for_exec(). However, to enforce a consistent and
> complete access control (e.g. on binary's dependencies) LSMs should
> restrict file executability, or mesure executed files, with
> security_file_open() by checking file->f_flags & __FMODE_EXEC.
>
> Because AT_EXECVE_CHECK is dedicated to user space interpreters, it
> doesn't make sense for the kernel to parse the checked files, look for
> interpreters known to the kernel (e.g. ELF, shebang), and return ENOEXEC
> if the format is unknown. Because of that, security_bprm_check() is
> never called when AT_EXECVE_CHECK is used.
>
> It should be noted that script interpreters cannot directly use
> execveat(2) (without this new AT_EXECVE_CHECK flag) because this could
> lead to unexpected behaviors e.g., `python script.sh` could lead to Bash
> being executed to interpret the script. Unlike the kernel, script
> interpreters may just interpret the shebang as a simple comment, which
> should not change for backward compatibility reasons.
>
> Because scripts or libraries files might not currently have the
> executable permission set, or because we might want specific users to be
> allowed to run arbitrary scripts, the following patch provides a dynamic
> configuration mechanism with the SECBIT_EXEC_RESTRICT_FILE and
> SECBIT_EXEC_DENY_INTERACTIVE securebits.
>
> This is a redesign of the CLIP OS 4's O_MAYEXEC:
> https://github.com/clipos-archive/src_platform_clip-patches/blob/f5cb330d6b684752e403b4e41b39f7004d88e561/1901_open_mayexec.patch
> This patch has been used for more than a decade with customized script
> interpreters. Some examples can be found here:
> https://github.com/clipos-archive/clipos4_portage-overlay/search?q=O_MAYEXEC
>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Christian Brauner <brauner@kernel.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Paul Moore <paul@paul-moore.com>
> Reviewed-by: Serge Hallyn <serge@hallyn.com>
> Link: https://docs.python.org/3/library/io.html#io.open_code [1]
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Link: https://lore.kernel.org/r/20241112191858.162021-2-mic@digikod.net
> ---
>
> Changes since v20:
> * Rename AT_CHECK to AT_EXECVE_CHECK, requested by Amir Goldstein and
> Serge Hallyn.
> * Move the UAPI documentation to a dedicated RST file.
> * Add Reviewed-by: Serge Hallyn
>
> Changes since v19:
> * Remove mention of "role transition" as suggested by Andy.
> * Highlight the difference between security_bprm_creds_for_exec() and
> the __FMODE_EXEC check for LSMs (in commit message and LSM's hooks) as
> discussed with Jeff.
> * Improve documentation both in UAPI comments and kernel comments
> (requested by Kees).
>
> New design since v18:
> https://lore.kernel.org/r/20220104155024.48023-3-mic@digikod.net
> ---
> Documentation/userspace-api/check_exec.rst | 34 ++++++++++++++++++++++
> Documentation/userspace-api/index.rst | 1 +
> fs/exec.c | 20 +++++++++++--
> include/linux/binfmts.h | 7 ++++-
> include/uapi/linux/fcntl.h | 4 +++
> kernel/audit.h | 1 +
> kernel/auditsc.c | 1 +
> security/security.c | 10 +++++++
> 8 files changed, 75 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/userspace-api/check_exec.rst
>
> diff --git a/Documentation/userspace-api/check_exec.rst b/Documentation/userspace-api/check_exec.rst
> new file mode 100644
> index 000000000000..ad1aeaa5f6c0
> --- /dev/null
> +++ b/Documentation/userspace-api/check_exec.rst
> @@ -0,0 +1,34 @@
> +===================
> +Executability check
> +===================
> +
> +AT_EXECVE_CHECK
> +===============
> +
> +Passing the ``AT_EXECVE_CHECK`` flag to :manpage:`execveat(2)` only performs a
> +check on a regular file and returns 0 if execution of this file would be
> +allowed, ignoring the file format and then the related interpreter dependencies
> +(e.g. ELF libraries, script's shebang).
> +
> +Programs should always perform this check to apply kernel-level checks against
> +files that are not directly executed by the kernel but passed to a user space
> +interpreter instead. All files that contain executable code, from the point of
> +view of the interpreter, should be checked. However the result of this check
> +should only be enforced according to ``SECBIT_EXEC_RESTRICT_FILE`` or
> +``SECBIT_EXEC_DENY_INTERACTIVE.``.
Regarding "should only"
Userspace (e.g. libc) could decide to enforce even when
SECBIT_EXEC_RESTRICT_FILE=0), i.e. if it determines not-enforcing
doesn't make sense.
When SECBIT_EXEC_RESTRICT_FILE=1, userspace is bound to enforce.
> +
> +The main purpose of this flag is to improve the security and consistency of an
> +execution environment to ensure that direct file execution (e.g.
> +``./script.sh``) and indirect file execution (e.g. ``sh script.sh``) lead to
> +the same result. For instance, this can be used to check if a file is
> +trustworthy according to the caller's environment.
> +
> +In a secure environment, libraries and any executable dependencies should also
> +be checked. For instance, dynamic linking should make sure that all libraries
> +are allowed for execution to avoid trivial bypass (e.g. using ``LD_PRELOAD``).
> +For such secure execution environment to make sense, only trusted code should
> +be executable, which also requires integrity guarantees.
> +
> +To avoid race conditions leading to time-of-check to time-of-use issues,
> +``AT_EXECVE_CHECK`` should be used with ``AT_EMPTY_PATH`` to check against a
> +file descriptor instead of a path.
> diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
> index 274cc7546efc..6272bcf11296 100644
> --- a/Documentation/userspace-api/index.rst
> +++ b/Documentation/userspace-api/index.rst
> @@ -35,6 +35,7 @@ Security-related interfaces
> mfd_noexec
> spec_ctrl
> tee
> + check_exec
>
> Devices and I/O
> ===============
> diff --git a/fs/exec.c b/fs/exec.c
> index 6c53920795c2..bb83b6a39530 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -891,7 +891,8 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
> .lookup_flags = LOOKUP_FOLLOW,
> };
>
> - if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
> + if ((flags &
> + ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH | AT_EXECVE_CHECK)) != 0)
> return ERR_PTR(-EINVAL);
> if (flags & AT_SYMLINK_NOFOLLOW)
> open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
> @@ -1545,6 +1546,21 @@ static struct linux_binprm *alloc_bprm(int fd, struct filename *filename, int fl
> }
> bprm->interp = bprm->filename;
>
> + /*
> + * At this point, security_file_open() has already been called (with
> + * __FMODE_EXEC) and access control checks for AT_EXECVE_CHECK will
> + * stop just after the security_bprm_creds_for_exec() call in
> + * bprm_execve(). Indeed, the kernel should not try to parse the
> + * content of the file with exec_binprm() nor change the calling
> + * thread, which means that the following security functions will be
> + * not called:
> + * - security_bprm_check()
> + * - security_bprm_creds_from_file()
> + * - security_bprm_committing_creds()
> + * - security_bprm_committed_creds()
> + */
> + bprm->is_check = !!(flags & AT_EXECVE_CHECK);
> +
> retval = bprm_mm_init(bprm);
> if (!retval)
> return bprm;
> @@ -1839,7 +1855,7 @@ static int bprm_execve(struct linux_binprm *bprm)
>
> /* Set the unchanging part of bprm->cred */
> retval = security_bprm_creds_for_exec(bprm);
> - if (retval)
> + if (retval || bprm->is_check)
> goto out;
>
> retval = exec_binprm(bprm);
> diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
> index e6c00e860951..8ff0eb3644a1 100644
> --- a/include/linux/binfmts.h
> +++ b/include/linux/binfmts.h
> @@ -42,7 +42,12 @@ struct linux_binprm {
> * Set when errors can no longer be returned to the
> * original userspace.
> */
> - point_of_no_return:1;
> + point_of_no_return:1,
> + /*
> + * Set by user space to check executability according to the
> + * caller's environment.
> + */
> + is_check:1;
> struct file *executable; /* Executable to pass to the interpreter */
> struct file *interpreter;
> struct file *file;
> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
> index 87e2dec79fea..2e87f2e3a79f 100644
> --- a/include/uapi/linux/fcntl.h
> +++ b/include/uapi/linux/fcntl.h
> @@ -154,6 +154,10 @@
> usable with open_by_handle_at(2). */
> #define AT_HANDLE_MNT_ID_UNIQUE 0x001 /* Return the u64 unique mount ID. */
>
> +/* Flags for execveat2(2). */
> +#define AT_EXECVE_CHECK 0x10000 /* Only perform a check if execution
> + would be allowed. */
> +
> #if defined(__KERNEL__)
> #define AT_GETATTR_NOSEC 0x80000000
> #endif
> diff --git a/kernel/audit.h b/kernel/audit.h
> index a60d2840559e..8ebdabd2ab81 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -197,6 +197,7 @@ struct audit_context {
> struct open_how openat2;
> struct {
> int argc;
> + bool is_check;
> } execve;
> struct {
> char *name;
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index cd57053b4a69..8d9ba5600cf2 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2662,6 +2662,7 @@ void __audit_bprm(struct linux_binprm *bprm)
>
> context->type = AUDIT_EXECVE;
> context->execve.argc = bprm->argc;
> + context->execve.is_check = bprm->is_check;
Where is execve.is_check used ?
> }
>
>
> diff --git a/security/security.c b/security/security.c
> index c5981e558bc2..456361ec249d 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1249,6 +1249,12 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
> * to 1 if AT_SECURE should be set to request libc enable secure mode. @bprm
> * contains the linux_binprm structure.
> *
> + * If execveat(2) is called with the AT_EXECVE_CHECK flag, bprm->is_check is
> + * set. The result must be the same as without this flag even if the execution
> + * will never really happen and @bprm will always be dropped.
> + *
> + * This hook must not change current->cred, only @bprm->cred.
> + *
> * Return: Returns 0 if the hook is successful and permission is granted.
> */
> int security_bprm_creds_for_exec(struct linux_binprm *bprm)
> @@ -3100,6 +3106,10 @@ int security_file_receive(struct file *file)
> * Save open-time permission checking state for later use upon file_permission,
> * and recheck access if anything has changed since inode_permission.
> *
> + * We can check if a file is opened for execution (e.g. execve(2) call), either
> + * directly or indirectly (e.g. ELF's ld.so) by checking file->f_flags &
> + * __FMODE_EXEC .
> + *
> * Return: Returns 0 if permission is granted.
> */
> int security_file_open(struct file *file)
> --
> 2.47.0
>
>
^ permalink raw reply
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