[RFC PATCH v7 04/16] ipe: add userspace interface

deven.desai
2021-10-13T19:06:49Z

From: Deven Bowers <deven.desai@linux.microsoft.com>

As is typical with LSMs, IPE uses securityfs as its interface with
userspace. for a complete list of the interfaces and the respective
inputs/outputs, please see the documentation under
admin-guide/LSM/ipe.rst

Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
---

Relevant changes since v6:
* Refactor series to:
1. Support a context structure, enabling easier testing
* Split up patch 03/12 into two parts:
1. parser [02/16]
2. userspace interface [04/16] (this patch)
* Interface changes:
1. "raw" was renamed to "pkcs7" and made read only
2. "raw"'s write functionality (update a policy) moved to "update"
3. introduced "version", "policy_name" nodes.
4. "content" renamed to "policy"
5. The boot policy can now be updated like any other policy.

---
security/ipe/Makefile | 2 +
security/ipe/ctx.c | 121 +++++++++
security/ipe/ctx.h | 6 +
security/ipe/fs.c | 170 +++++++++++++
security/ipe/fs.h | 13 +
security/ipe/policy.c | 41 ++++
security/ipe/policy.h | 4 +
security/ipe/policyfs.c | 528 ++++++++++++++++++++++++++++++++++++++++
8 files changed, 885 insertions(+)
create mode 100644 security/ipe/fs.c
create mode 100644 security/ipe/fs.h
create mode 100644 security/ipe/policyfs.c

diff --git a/security/ipe/Makefile b/security/ipe/Makefile
index 0db69f13e82a..d5660a17364c 100644
--- a/security/ipe/Makefile
+++ b/security/ipe/Makefile
@@ -10,9 +10,11 @@ ccflags-y := -I$(srctree)/security/ipe/modules
obj-$(CONFIG_SECURITY_IPE) += \
ctx.o \
eval.o \
+ fs.o \
hooks.o \
ipe.o \
modules.o \
parsers/ \
parsers.o \
policy.o \
+ policyfs.o \
diff --git a/security/ipe/ctx.c b/security/ipe/ctx.c
index 9274e51eff52..664c671a4f9c 100644
--- a/security/ipe/ctx.c
+++ b/security/ipe/ctx.c
@@ -13,6 +13,29 @@
#include <linux/refcount.h>
#include <linux/spinlock.h>

+/**
+ * ver_to_u64: convert an internal ipe_policy_version to a u64
+ * @p: Policy to extract the version from
+ *
+ * Bits (LSB is index 0):
+ * [48,32] -> Major
+ * [32,16] -> Minor
+ * [16, 0] -> Revision
+ *
+ * Return:
+ * u64 version of the embedded version structure.
+ */
+static inline u64 ver_to_u64(const struct ipe_policy *const p)
+{
+ u64 r = 0;
+
+ r = (((u64)p->parsed->version.major) << 32)
+ | (((u64)p->parsed->version.minor) << 16)
+ | ((u64)(p->parsed->version.rev));
+
+ return r;
+}
+
/**
* ipe_current_ctx: Helper to retrieve the ipe_context for the current task.
*
@@ -96,6 +119,7 @@ static void free_ctx_work(struct work_struct *const work)
list_for_each_entry(p, &ctx->policies, next)
ipe_put_policy(p);

+ securityfs_remove(ctx->policy_root);
kfree(ctx);
}

@@ -160,6 +184,9 @@ void ipe_remove_policy(struct ipe_policy *p)
* ipe_add_policy: Associate @p with @ctx
* @ctx: Supplies a pointer to the ipe_context structure to associate @p with.
* @p: Supplies a pointer to the ipe_policy structure to associate.
+ *
+ * This will increase @p's reference count by one.
+ *
*/
void ipe_add_policy(struct ipe_context *ctx, struct ipe_policy *p)
{
@@ -168,7 +195,101 @@ void ipe_add_policy(struct ipe_context *ctx, struct ipe_policy *p)
list_add_tail(&p->next, &ctx->policies);
refcount_inc(&p->refcount);
spin_unlock(&ctx->lock);
+}
+
+/**
+ * ipe_replace_policy: Replace @old with @new in the list of policies in @ctx
+ * @ctx: Supplies the context object to manipulate.
+ * @old: Supplies a pointer to the ipe_policy to replace with @new
+ * @new: Supplies a pointer to the ipe_policy structure to replace @old with
+ */
+int ipe_replace_policy(struct ipe_policy *old, struct ipe_policy *new)
+{
+ int rc = -EINVAL;
+ struct ipe_context *ctx;
+ struct ipe_policy *cursor;
+ struct ipe_policy *p = NULL;
+
+ ctx = ipe_get_ctx_rcu(old->ctx);
+ if (!ctx)
+ return -ENOENT;
+
+ spin_lock(&ctx->lock);
+ list_for_each_entry(cursor, &ctx->policies, next) {
+ if (!strcmp(old->parsed->name, cursor->parsed->name)) {
+ if (ipe_is_policy_active(old)) {
+ if (ver_to_u64(old) > ver_to_u64(new))
+ break;
+ rcu_assign_pointer(ctx->active_policy, new);
+ }
+ list_replace_init(&cursor->next, &new->next);
+ refcount_inc(&new->refcount);
+ rcu_assign_pointer(new->ctx, old->ctx);
+ p = cursor;
+ rc = 0;
+ break;
+ }
+ }
+ spin_unlock(&ctx->lock);
+ synchronize_rcu();
+
+ ipe_put_policy(p);
+ ipe_put_ctx(ctx);
+ return rc;
+}
+
+/**
+ * ipe_set_active_pol: Make @p the active policy.
+ * @p: Supplies a pointer to the policy to make active.
+ */
+int ipe_set_active_pol(const struct ipe_policy *p)
+{
+ int rc = 0;
+ struct ipe_policy *ap = NULL;
+ struct ipe_context *ctx = NULL;
+
+ ctx = ipe_get_ctx_rcu(p->ctx);
+ if (!ctx) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ ap = ipe_get_policy_rcu(ctx->active_policy);
+ if (ap && ver_to_u64(ap) > ver_to_u64(p)) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ spin_lock(&ctx->lock);
+ rcu_assign_pointer(ctx->active_policy, p);
+ spin_unlock(&ctx->lock);
synchronize_rcu();
+
+out:
+ ipe_put_policy(ap);
+ ipe_put_ctx(ctx);
+ return rc;
+}
+
+/**
+ * ipe_is_policy_active: Determine wehther @p is the active policy
+ * @p: Supplies a pointer to the policy to check.
+ *
+ * Return:
+ * true - @p is the active policy of @ctx
+ * false - @p is not the active policy of @ctx
+ */
+bool ipe_is_policy_active(const struct ipe_policy *p)
+{
+ bool rv;
+ struct ipe_context *ctx;
+
+ rcu_read_lock();
+ ctx = rcu_dereference(p->ctx);
+ rv = !IS_ERR_OR_NULL(ctx) && rcu_access_pointer(ctx->active_policy) == p;
+ rcu_read_unlock();
+
+ return rv;
}

/**
diff --git a/security/ipe/ctx.h b/security/ipe/ctx.h
index a0da92da818c..fe11fb767788 100644
--- a/security/ipe/ctx.h
+++ b/security/ipe/ctx.h
@@ -7,6 +7,7 @@

#include <linux/sched.h>
#include <linux/types.h>
+#include <linux/dcache.h>
#include <linux/refcount.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
@@ -20,6 +21,8 @@ struct ipe_context {

struct list_head policies; /* type: ipe_policy */

+ struct dentry *policy_root;
+
struct work_struct free_work;
};

@@ -30,5 +33,8 @@ struct ipe_context *ipe_get_ctx_rcu(struct ipe_context __rcu *ctx);
void ipe_put_ctx(struct ipe_context *ctx);
void ipe_add_policy(struct ipe_context *ctx, struct ipe_policy *p);
void ipe_remove_policy(struct ipe_policy *p);
+int ipe_replace_policy(struct ipe_policy *old, struct ipe_policy *new);
+int ipe_set_active_pol(const struct ipe_policy *p);
+bool ipe_is_policy_active(const struct ipe_policy *p);

#endif /* IPE_CONTEXT_H */
diff --git a/security/ipe/fs.c b/security/ipe/fs.c
new file mode 100644
index 000000000000..10ad23f8bf92
--- /dev/null
+++ b/security/ipe/fs.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#include "ipe.h"
+#include "fs.h"
+#include "policy.h"
+
+#include <linux/dcache.h>
+#include <linux/security.h>
+
+static struct dentry *np __ro_after_init;
+static struct dentry *root __ro_after_init;
+static struct dentry *config __ro_after_init;
+
+/**
+ * new_policy: Write handler for the securityfs node, "ipe/new_policy"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t new_policy(struct file *f, const char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ char *copy = NULL;
+ struct ipe_policy *p = NULL;
+ struct ipe_context *ctx = NULL;
+
+ if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+ return -EPERM;
+
+ ctx = ipe_current_ctx();
+
+ copy = memdup_user_nul(data, len);
+ if (IS_ERR(copy)) {
+ rc = PTR_ERR(copy);
+ goto err;
+ }
+
+ p = ipe_new_policy(NULL, 0, copy, len);
+ if (IS_ERR(p)) {
+ rc = PTR_ERR(p);
+ goto err;
+ }
+
+ rc = ipe_new_policyfs_node(ctx, p);
+ if (rc)
+ goto err;
+
+ ipe_add_policy(ctx, p);
+err:
+ ipe_put_policy(p);
+ ipe_put_ctx(ctx);
+ return (rc < 0) ? rc : len;
+}
+
+/**
+ * get_config: Read handler for the securityfs node, "ipe/config"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the read syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t get_config(struct file *f, char __user *data, size_t len,
+ loff_t *offset)
+{
+ int rc = 0;
+ char *buf = NULL;
+ size_t buflen = 0;
+ char tmp[30] = { 0 };
+ struct ipe_parser *p = NULL;
+ struct ipe_module *m = NULL;
+
+ for (p = __start_ipe_parsers; p < __end_ipe_parsers; ++p)
+ buflen += snprintf(NULL, 0, "%s=%d\n", p->first_token, p->version);
+ for (m = __start_ipe_modules; m < __end_ipe_modules; ++m)
+ buflen += snprintf(NULL, 0, "%s=%d\n", m->name, m->version);
+
+ ++buflen;
+ buf = kzalloc(buflen, GFP_KERNEL);
+ if (!buf) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ for (p = __start_ipe_parsers; p < __end_ipe_parsers; ++p) {
+ memset(tmp, 0x0, ARRAY_SIZE(tmp));
+ scnprintf(tmp, ARRAY_SIZE(tmp), "%s=%d\n", p->first_token, p->version);
+ strcat(buf, tmp);
+ }
+
+ for (m = __start_ipe_modules; m < __end_ipe_modules; ++m) {
+ memset(tmp, 0x0, ARRAY_SIZE(tmp));
+ scnprintf(tmp, ARRAY_SIZE(tmp), "%s=%d\n", m->name, m->version);
+ strcat(buf, tmp);
+ }
+
+ rc = simple_read_from_buffer(data, len, offset, buf, buflen);
+out:
+ kfree(buf);
+ return rc;
+}
+
+static const struct file_operations cfg_fops = {
+ .read = get_config,
+};
+
+static const struct file_operations np_fops = {
+ .write = new_policy,
+};
+
+/**
+ * ipe_init_securityfs: Initialize IPE's securityfs tree at fsinit
+ *
+ * Return:
+ * !0 - Error
+ * 0 - OK
+ */
+static int __init ipe_init_securityfs(void)
+{
+ int rc = 0;
+ struct ipe_context *ctx = NULL;
+
+ ctx = ipe_current_ctx();
+
+ root = securityfs_create_dir("ipe", NULL);
+ if (IS_ERR(root)) {
+ rc = PTR_ERR(root);
+ goto err;
+ }
+
+ np = securityfs_create_file("new_policy", 0200, root, NULL, &np_fops);
+ if (IS_ERR(np)) {
+ rc = PTR_ERR(np);
+ goto err;
+ }
+
+ config = securityfs_create_file("config", 0400, root, NULL,
+ &cfg_fops);
+ if (IS_ERR(config)) {
+ rc = PTR_ERR(config);
+ goto err;
+ }
+
+ ctx->policy_root = securityfs_create_dir("policies", root);
+ if (IS_ERR(ctx->policy_root)) {
+ rc = PTR_ERR(ctx->policy_root);
+ goto err;
+ }
+
+ return 0;
+err:
+ securityfs_remove(np);
+ securityfs_remove(root);
+ securityfs_remove(config);
+ securityfs_remove(ctx->policy_root);
+ return rc;
+}
+
+fs_initcall(ipe_init_securityfs);
diff --git a/security/ipe/fs.h b/security/ipe/fs.h
new file mode 100644
index 000000000000..4ab2f4e8c454
--- /dev/null
+++ b/security/ipe/fs.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+
+#ifndef IPE_FS_H
+#define IPE_FS_H
+
+void ipe_soft_del_policyfs(struct ipe_policy *p);
+int ipe_new_policyfs_node(struct ipe_context *ctx, struct ipe_policy *p);
+void ipe_del_policyfs_node(struct ipe_policy *p);
+
+#endif /* IPE_FS_H */
diff --git a/security/ipe/policy.c b/security/ipe/policy.c
index 8970f96453d6..b766824cc08f 100644
--- a/security/ipe/policy.c
+++ b/security/ipe/policy.c
@@ -4,6 +4,7 @@
*/

#include "ipe.h"
+#include "fs.h"
#include "policy.h"
#include "ipe_parser.h"
#include "modules.h"
@@ -867,6 +868,8 @@ void ipe_put_policy(struct ipe_policy *p)
if (IS_ERR_OR_NULL(p) || !refcount_dec_and_test(&p->refcount))
return;

+ ipe_del_policyfs_node(p);
+ securityfs_remove(p->policyfs);
free_parsed_policy(p->parsed);
if (!p->pkcs7)
kfree(p->text);
@@ -911,6 +914,44 @@ static int set_pkcs7_data(void *ctx, const void *data, size_t len,
return 0;
}

+/**
+ * ipe_update_policy: parse a new policy and replace @old with it.
+ * @old: Supplies a pointer to the policy to replace
+ * @text: Supplies a pointer to the plain text policy
+ * @textlen: Supplies the length of @text
+ * @pkcs7: Supplies a pointer to a buffer containing a pkcs7 message.
+ * @pkcs7len: Supplies the length of @pkcs7len
+ *
+ * @text/@textlen is mutually exclusive with @pkcs7/@pkcs7len - see
+ * ipe_new_policy.
+ *
+ * Return:
+ * !IS_ERR - OK
+ */
+struct ipe_policy *ipe_update_policy(struct ipe_policy *old,
+ const char *text, size_t textlen,
+ const char *pkcs7, size_t pkcs7len)
+{
+ int rc = 0;
+ struct ipe_policy *new;
+
+ new = ipe_new_policy(text, textlen, pkcs7, pkcs7len);
+ if (IS_ERR(new)) {
+ rc = PTR_ERR(new);
+ goto err;
+ }
+
+ if (strcmp(new->parsed->name, old->parsed->name)) {
+ rc = -EINVAL;
+ goto err;
+ }
+
+ rc = ipe_replace_policy(old, new);
+err:
+ ipe_put_policy(new);
+ return (rc < 0) ? ERR_PTR(rc) : new;
+}
+
/**
* ipe_new_policy: allocate and parse an ipe_policy structure.
*
diff --git a/security/ipe/policy.h b/security/ipe/policy.h
index 2b5041c5a75a..6818f6405dd0 100644
--- a/security/ipe/policy.h
+++ b/security/ipe/policy.h
@@ -88,12 +88,16 @@ struct ipe_policy {

refcount_t refcount;

+ struct dentry *policyfs;
struct list_head next; /* type: ipe_policy */
struct ipe_context __rcu *ctx;
};

struct ipe_policy *ipe_new_policy(const char *text, size_t textlen,
const char *pkcs7, size_t pkcs7len);
+struct ipe_policy *ipe_update_policy(struct ipe_policy *old, const char *text,
+ size_t textlen, const char *pkcs7,
+ size_t pkcs7len);
void ipe_put_policy(struct ipe_policy *pol);
bool ipe_is_op_alias(int op, const enum ipe_operation **map, size_t *size);
struct ipe_policy *ipe_get_policy_rcu(struct ipe_policy __rcu *p);
diff --git a/security/ipe/policyfs.c b/security/ipe/policyfs.c
new file mode 100644
index 000000000000..d34c22e99225
--- /dev/null
+++ b/security/ipe/policyfs.c
@@ -0,0 +1,528 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ */
+#include "ipe.h"
+#include "policy.h"
+#include "fs.h"
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/types.h>
+#include <linux/dcache.h>
+#include <linux/security.h>
+
+#define MAX_VERSION_SIZE ARRAY_SIZE("65535.65535.65535")
+
+/**
+ * find_policy: Follow the i_private field of a dentry, returning the address
+ * of the resulting policy structure.
+ * @f: Securityfs object that contains a link to the dentry containing the
+ * policy structure.
+ *
+ * Return:
+ * Always-Valid Address Pointer
+ */
+static inline struct ipe_policy __rcu **find_policy(struct file *f)
+{
+ struct dentry *link;
+
+ link = d_inode(f->f_path.dentry)->i_private;
+
+ return (struct ipe_policy __rcu **)&(d_inode(link)->i_private);
+}
+
+/**
+ * ipefs_file: defines a file in securityfs
+ */
+struct ipefs_file {
+ const char *name;
+ umode_t access;
+ const struct file_operations *fops;
+};
+
+/**
+ * read_pkcs7: Read handler for the securityfs node,
+ * "ipe/policies/$name/pkcs7"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * @data will be populated with the pkcs7 blob representing the policy
+ * on success. If the policy is unsigned (like the boot policy), this
+ * will return -ENOENT.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t read_pkcs7(struct file *f, char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ struct ipe_policy *p = NULL;
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p)
+ return -ENOENT;
+
+ if (!p->pkcs7) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ rc = simple_read_from_buffer(data, len, offset, p->pkcs7, p->pkcs7len);
+
+out:
+ ipe_put_policy(p);
+ return rc;
+}
+
+/**
+ * read_policy: Read handler for the securityfs node,
+ * "ipe/policies/$name/policy"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * @data will be populated with the plain-text version of the policy
+ * on success.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t read_policy(struct file *f, char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ struct ipe_policy *p = NULL;
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p)
+ return -ENOENT;
+
+ rc = simple_read_from_buffer(data, len, offset, p->text, p->textlen);
+
+ ipe_put_policy(p);
+ return rc;
+}
+
+/**
+ * read_name: Read handler for the securityfs node,
+ * "ipe/policies/$name/name"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * @data will be populated with the policy_name attribute on success
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t read_name(struct file *f, char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ struct ipe_policy *p = NULL;
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p)
+ return -ENOENT;
+
+ rc = simple_read_from_buffer(data, len, offset, p->parsed->name,
+ strlen(p->parsed->name));
+
+ ipe_put_policy(p);
+ return rc;
+}
+
+/**
+ * read_version: Read handler for the securityfs node,
+ * "ipe/policies/$name/version"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * @data will be populated with the version string on success.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t read_version(struct file *f, char __user *data,
+ size_t len, loff_t *offset)
+{
+ ssize_t rc = 0;
+ size_t bufsize = 0;
+ struct ipe_policy *p = NULL;
+ char buffer[MAX_VERSION_SIZE] = { 0 };
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p)
+ return -ENOENT;
+
+ bufsize = scnprintf(buffer, ARRAY_SIZE(buffer), "%hu.%hu.%hu",
+ p->parsed->version.major, p->parsed->version.minor,
+ p->parsed->version.rev);
+
+ rc = simple_read_from_buffer(data, len, offset, buffer, bufsize);
+
+ ipe_put_policy(p);
+ return rc;
+}
+
+/**
+ * setactive: Write handler for the securityfs node,
+ * "ipe/policies/$name/active"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t setactive(struct file *f, const char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ bool value = false;
+ struct ipe_policy *p = NULL;
+ struct ipe_context *ctx = NULL;
+
+ if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+ return -EPERM;
+
+ rc = kstrtobool_from_user(data, len, &value);
+ if (rc)
+ goto out;
+
+ if (!value) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ ctx = ipe_get_ctx_rcu(p->ctx);
+ if (!ctx) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ rc = ipe_set_active_pol(p);
+
+out:
+ ipe_put_ctx(ctx);
+ ipe_put_policy(p);
+ return (rc < 0) ? rc : len;
+}
+
+/**
+ * getactive: Read handler for the securityfs node,
+ * "ipe/policies/$name/active"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Suppleis a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * @data will be populated with the 1 or 0 depending on if the
+ * corresponding policy is active.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t getactive(struct file *f, char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ const char *str;
+ struct ipe_policy *p = NULL;
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ str = ipe_is_policy_active(p) ? "1" : "0";
+ rc = simple_read_from_buffer(data, len, offset, str, 2);
+
+out:
+ ipe_put_policy(p);
+ return rc;
+}
+
+/**
+ * update_policy: Write handler for the securityfs node,
+ * "ipe/policies/$name/active"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * On success this updates the policy represented by $name,
+ * in-place.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t update_policy(struct file *f, const char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ char *copy = NULL;
+ struct ipe_policy *new = NULL;
+ struct ipe_policy *old = NULL;
+ struct ipe_context *ctx = NULL;
+ struct ipe_policy __rcu **addr = NULL;
+
+ if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+ return -EPERM;
+
+ ctx = ipe_current_ctx();
+ if (!ctx)
+ return -ENOENT;
+
+ addr = find_policy(f);
+ old = ipe_get_policy_rcu(*addr);
+ if (!old) {
+ rc = -ENOENT;
+ goto err;
+ }
+
+ copy = memdup_user(data, len);
+ if (IS_ERR(copy)) {
+ rc = PTR_ERR(copy);
+ goto err;
+ }
+
+ new = ipe_update_policy(old, NULL, 0, copy, len);
+ if (IS_ERR(new)) {
+ rc = PTR_ERR(new);
+ goto err;
+ }
+
+ spin_lock(&ctx->lock);
+ rcu_assign_pointer(*addr, new);
+ spin_unlock(&ctx->lock);
+ synchronize_rcu();
+
+ swap(new->policyfs, old->policyfs);
+
+ kfree(copy);
+ ipe_put_ctx(ctx);
+ ipe_put_policy(old);
+ return len;
+err:
+ kfree(copy);
+ ipe_put_ctx(ctx);
+ ipe_put_policy(new);
+ ipe_put_policy(old);
+ return rc;
+}
+
+/**
+ * delete_policy: write handler for securityfs dir, "ipe/policies/$name/delete"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall
+ * @len: Supplies the length of @data
+ * @offset: unused.
+ *
+ * On success this deletes the policy represented by $name.
+ *
+ * Return:
+ * >0 - Success, Length of buffer written
+ * <0 - Error
+ */
+static ssize_t delete_policy(struct file *f, const char __user *data,
+ size_t len, loff_t *offset)
+{
+ int rc = 0;
+ bool value = false;
+ struct ipe_policy *p = NULL;
+ struct ipe_context *ctx = NULL;
+
+ if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+ return -EPERM;
+
+ rc = kstrtobool_from_user(data, len, &value);
+ if (rc)
+ goto out;
+
+ if (!value) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ p = ipe_get_policy_rcu(*find_policy(f));
+ if (!p) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ if (ipe_is_policy_active(p)) {
+ rc = -EPERM;
+ goto out;
+ }
+
+ ctx = ipe_get_ctx_rcu(p->ctx);
+ if (!ctx) {
+ rc = -ENOENT;
+ goto out;
+ }
+
+ ipe_remove_policy(p);
+out:
+ ipe_put_ctx(ctx);
+ ipe_put_policy(p);
+ return (rc < 0) ? rc : len;
+}
+
+static const struct file_operations content_fops = {
+ .read = read_policy,
+};
+
+static const struct file_operations pkcs7_fops = {
+ .read = read_pkcs7,
+};
+
+static const struct file_operations name_fops = {
+ .read = read_name,
+};
+
+static const struct file_operations ver_fops = {
+ .read = read_version,
+};
+
+static const struct file_operations active_fops = {
+ .write = setactive,
+ .read = getactive,
+};
+
+static const struct file_operations update_fops = {
+ .write = update_policy,
+};
+
+static const struct file_operations delete_fops = {
+ .write = delete_policy,
+};
+
+/**
+ * policy_subdir: files under a policy subdirectory
+ */
+static const struct ipefs_file policy_subdir[] = {
+ { "pkcs7", 0444, &pkcs7_fops },
+ { "policy", 0444, &content_fops },
+ { "name", 0444, &name_fops },
+ { "version", 0444, &ver_fops },
+ { "active", 0600, &active_fops },
+ { "update", 0200, &update_fops },
+ { "delete", 0200, &delete_fops },
+};
+
+/**
+ * soft_del_policyfs - soft delete the policyfs tree, preventing new
+ * accesses to the interfaces for this policy.
+ * @p - Policy to soft delete the tree for.
+ */
+static void soft_del_policyfs(struct ipe_policy *p)
+{
+ struct inode *ino = NULL;
+ struct ipe_policy __rcu **addr = NULL;
+
+ ino = d_inode(p->policyfs);
+ addr = (struct ipe_policy __rcu **)&ino->i_private;
+
+ inode_lock(ino);
+ rcu_assign_pointer(*addr, NULL);
+ inode_unlock(ino);
+ synchronize_rcu();
+}
+
+/**
+ * ipe_del_policyfs_node: Delete a securityfs entry for @p
+ * @p: Supplies a pointer to the policy to delete a securityfs entry for.
+ */
+void ipe_del_policyfs_node(struct ipe_policy *p)
+{
+ size_t i = 0;
+ struct dentry *d = NULL;
+ const struct ipefs_file *f = NULL;
+
+ if (IS_ERR_OR_NULL(p->policyfs))
+ return;
+
+ soft_del_policyfs(p);
+
+ for (i = 0; i < ARRAY_SIZE(policy_subdir); ++i) {
+ f = &policy_subdir[i];
+
+ d = lookup_positive_unlocked(f->name, p->policyfs,
+ strlen(f->name));
+ if (IS_ERR(d))
+ continue;
+
+ securityfs_remove(d);
+ dput(d);
+ }
+
+ securityfs_remove(p->policyfs);
+}
+
+/**
+ * ipe_new_policyfs_node: Create a securityfs entry for @p
+ * @ctx: Supplies a pointer to a context structure that contains the root of
+ * the policy tree.
+ * @p: Supplies a pointer to the policy to create a securityfs entry for.
+ *
+ * Return:
+ * 0 - OK
+ * !0 - Error
+ */
+int ipe_new_policyfs_node(struct ipe_context *ctx, struct ipe_policy *p)
+{
+ int rc = 0;
+ size_t i = 0;
+ struct dentry *d = NULL;
+ struct ipe_policy **addr = NULL;
+ const struct ipefs_file *f = NULL;
+
+ p->policyfs = securityfs_create_dir(p->parsed->name, ctx->policy_root);
+ if (IS_ERR(p->policyfs)) {
+ rc = PTR_ERR(p->policyfs);
+ goto err;
+ }
+
+ addr = (struct ipe_policy **)&(d_inode(p->policyfs)->i_private);
+ *addr = p;
+
+ for (i = 0; i < ARRAY_SIZE(policy_subdir); ++i) {
+ f = &policy_subdir[i];
+
+ d = securityfs_create_file(f->name, f->access, p->policyfs, p->policyfs,
+ f->fops);
+ if (IS_ERR(d)) {
+ rc = PTR_ERR(d);
+ goto err;
+ }
+ }
+
+ return 0;
+err:
+ ipe_del_policyfs_node(p);
+ return rc;
+}
--
2.33.0