[PATCH v5 04/16] ima: Move delayed work queue and variables into ima_namespace

Stefan Berger
2021-12-08T22:18:40Z

Move the delayed work queue and associated variables to the
ima_namespace and initialize them.

Since keys queued up for measurement currently are only relevant in the
init_ima_ns, call ima_init_key_queue() only when the init_ima_ns is
initialized.

Protect the ima_namespace when scheduling the delayed work by taking an
additional reference to its user namespace. Put the reference when either
the delayed work has completed or when it was cancelled but hadn't run.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
include/linux/ima.h | 11 +++++++
security/integrity/ima/ima.h | 12 ++++---
security/integrity/ima/ima_fs.c | 4 ++-
security/integrity/ima/ima_init.c | 2 --
security/integrity/ima/ima_init_ima_ns.c | 8 +++++
security/integrity/ima/ima_policy.c | 4 +--
security/integrity/ima/ima_queue_keys.c | 42 +++++++++++++-----------
7 files changed, 53 insertions(+), 30 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 9f6de36240b0..529defe4d272 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -217,6 +217,17 @@ struct ima_namespace {
struct rb_root ns_status_tree;
rwlock_t ns_status_lock;
struct kmem_cache *ns_status_cache;
+
+#ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS
+ /*
+ * If custom IMA policy is not loaded then keys queued up
+ * for measurement should be freed. This worker is used
+ * for handling this scenario.
+ */
+ struct delayed_work ima_keys_delayed_work;
+ long ima_key_queue_timeout;
+ bool timer_expired;
+#endif
};

extern struct ima_namespace init_ima_ns;
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index dd06e16c4e1c..9edab9050dc7 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -77,6 +77,8 @@ struct ima_field_data {
u32 len;
};

+struct ima_namespace;
+
/* IMA template field definition */
struct ima_template_field {
const char field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN];
@@ -247,18 +249,18 @@ struct ima_key_entry {
size_t payload_len;
char *keyring_name;
};
-void ima_init_key_queue(void);
+void ima_init_key_queue(struct ima_namespace *ns);
bool ima_should_queue_key(void);
bool ima_queue_key(struct key *keyring, const void *payload,
size_t payload_len);
-void ima_process_queued_keys(void);
+void ima_process_queued_keys(struct ima_namespace *ns);
+void ima_keys_handler(struct work_struct *work);
#else
-static inline void ima_init_key_queue(void) {}
static inline bool ima_should_queue_key(void) { return false; }
static inline bool ima_queue_key(struct key *keyring,
const void *payload,
size_t payload_len) { return false; }
-static inline void ima_process_queued_keys(void) {}
+static inline void ima_process_queued_keys(struct ima_namespace *ns) {}
#endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */

/* LIM API function definitions */
@@ -300,7 +302,7 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
struct ima_template_desc **template_desc,
const char *func_data, unsigned int *allowed_algos);
void ima_init_policy(void);
-void ima_update_policy(void);
+void ima_update_policy(struct ima_namespace *ns);
void ima_update_policy_flags(void);
ssize_t ima_parse_add_rule(char *);
void ima_delete_rules(void);
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 3d8e9d5db5aa..5cff3d6c3dc7 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -21,6 +21,7 @@
#include <linux/rcupdate.h>
#include <linux/parser.h>
#include <linux/vmalloc.h>
+#include <linux/ima.h>

#include "ima.h"

@@ -410,6 +411,7 @@ static int ima_open_policy(struct inode *inode, struct file *filp)
static int ima_release_policy(struct inode *inode, struct file *file)
{
const char *cause = valid_policy ? "completed" : "failed";
+ struct ima_namespace *ns = get_current_ns();

if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_release(inode, file);
@@ -430,7 +432,7 @@ static int ima_release_policy(struct inode *inode, struct file *file)
return 0;
}

- ima_update_policy();
+ ima_update_policy(ns);
#if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)
securityfs_remove(ima_policy);
ima_policy = NULL;
diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
index f6ae4557a0da..24848373a061 100644
--- a/security/integrity/ima/ima_init.c
+++ b/security/integrity/ima/ima_init.c
@@ -155,8 +155,6 @@ int __init ima_init(void)
if (rc != 0)
return rc;

- ima_init_key_queue();
-
ima_measure_critical_data("kernel_info", "kernel_version",
UTS_RELEASE, strlen(UTS_RELEASE), false,
NULL, 0);
diff --git a/security/integrity/ima/ima_init_ima_ns.c b/security/integrity/ima/ima_init_ima_ns.c
index 64777377664b..75ef17d52b5b 100644
--- a/security/integrity/ima/ima_init_ima_ns.c
+++ b/security/integrity/ima/ima_init_ima_ns.c
@@ -26,6 +26,14 @@ int ima_init_namespace(struct ima_namespace *ns)
if (!ns->ns_status_cache)
return -ENOMEM;

+#ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS
+ INIT_DELAYED_WORK(&ns->ima_keys_delayed_work, ima_keys_handler);
+ ns->ima_key_queue_timeout = 300000;
+ ns->timer_expired = false;
+ if (ns == &init_ima_ns)
+ ima_init_key_queue(ns);
+#endif
+
return 0;
}

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 320ca80aacab..e5aef287d14d 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -986,7 +986,7 @@ int ima_check_policy(void)
* Policy rules are never deleted so ima_policy_flag gets zeroed only once when
* we switch from the default policy to user defined.
*/
-void ima_update_policy(void)
+void ima_update_policy(struct ima_namespace *ns)
{
struct list_head *policy = &ima_policy_rules;

@@ -1007,7 +1007,7 @@ void ima_update_policy(void)
ima_update_policy_flags();

/* Custom IMA policy has been loaded */
- ima_process_queued_keys();
+ ima_process_queued_keys(ns);
}

/* Keep the enumeration in sync with the policy_tokens! */
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index 93056c03bf5a..ed5923dfe71b 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -10,6 +10,7 @@

#include <linux/user_namespace.h>
#include <linux/workqueue.h>
+#include <linux/ima.h>
#include <keys/asymmetric-type.h>
#include "ima.h"

@@ -25,34 +26,32 @@ static bool ima_process_keys;
static DEFINE_MUTEX(ima_keys_lock);
static LIST_HEAD(ima_keys);

-/*
- * If custom IMA policy is not loaded then keys queued up
- * for measurement should be freed. This worker is used
- * for handling this scenario.
- */
-static long ima_key_queue_timeout = 300000; /* 5 Minutes */
-static void ima_keys_handler(struct work_struct *work);
-static DECLARE_DELAYED_WORK(ima_keys_delayed_work, ima_keys_handler);
-static bool timer_expired;
-
/*
* This worker function frees keys that may still be
* queued up in case custom IMA policy was not loaded.
*/
-static void ima_keys_handler(struct work_struct *work)
+void ima_keys_handler(struct work_struct *work)
{
- timer_expired = true;
- ima_process_queued_keys();
+ struct ima_namespace *ns;
+
+ ns = container_of(work, struct ima_namespace, ima_keys_delayed_work.work);
+ ns->timer_expired = true;
+ ima_process_queued_keys(ns);
+
+ put_user_ns(ns->user_ns);
}

/*
* This function sets up a worker to free queued keys in case
* custom IMA policy was never loaded.
*/
-void ima_init_key_queue(void)
+void ima_init_key_queue(struct ima_namespace *ns)
{
- schedule_delayed_work(&ima_keys_delayed_work,
- msecs_to_jiffies(ima_key_queue_timeout));
+ /* keep IMA namespace until delayed work is done */
+ get_user_ns(ns->user_ns);
+
+ schedule_delayed_work(&ns->ima_keys_delayed_work,
+ msecs_to_jiffies(ns->ima_key_queue_timeout));
}

static void ima_free_key_entry(struct ima_key_entry *entry)
@@ -130,7 +129,7 @@ bool ima_queue_key(struct key *keyring, const void *payload,
* This function sets ima_process_keys to true and processes queued keys.
* From here on keys will be processed right away (not queued).
*/
-void ima_process_queued_keys(void)
+void ima_process_queued_keys(struct ima_namespace *ns)
{
struct ima_key_entry *entry, *tmp;
bool process = false;
@@ -154,11 +153,14 @@ void ima_process_queued_keys(void)
if (!process)
return;

- if (!timer_expired)
- cancel_delayed_work_sync(&ima_keys_delayed_work);
+ if (!ns->timer_expired) {
+ if (cancel_delayed_work_sync(&ns->ima_keys_delayed_work))
+ /* undo reference from ima_init_key_queue */
+ put_user_ns(ns->user_ns);
+ }

list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
- if (!timer_expired)
+ if (!ns->timer_expired)
process_buffer_measurement(&init_user_ns, NULL,
entry->payload,
entry->payload_len,
--
2.31.1