[v5,03/16] ima: Namespace audit status flags

Commit Message

Stefan Berger Dec. 8, 2021, 10:18 p.m. UTC

From: Mehmet Kayaalp <[e-mail]>

The iint cache stores whether the file is measured, appraised, audited
etc. This patch moves the IMA_AUDITED flag into the per-namespace
ns_status, enabling IMA audit mechanism to audit the same file each time
it is accessed in a new namespace.

The ns_status is not looked up if the CONFIG_IMA_NS is disabled or if
any of the IMA_NS_STATUS_ACTIONS (currently only IMA_AUDIT) is not
enabled.

Read and write operations on the iint flags is replaced with function
calls. For reading, iint_flags() returns the bitwise AND of iint->flags
and ns_status->flags. The ns_status flags are masked with
IMA_NS_STATUS_FLAGS (currently only IMA_AUDITED). Similarly
set_iint_flags() only writes the masked portion to the ns_status flags,
while the iint flags is set as before. The ns_status parameter added to
ima_audit_measurement() is used with the above functions to query and
set the ns_status flags.

Signed-off-by: Mehmet Kayaalp <[e-mail]>

Changelog:
v2:
 * fixed flag calculation in iint_flags()
---
 init/Kconfig                      |  3 +++
 security/integrity/ima/ima.h      | 23 ++++++++++++++++++++++-
 security/integrity/ima/ima_api.c  |  8 +++++---
 security/integrity/ima/ima_main.c | 25 ++++++++++++++++++-------
 security/integrity/ima/ima_ns.c   | 20 ++++++++++++++++++++
 5 files changed, 68 insertions(+), 11 deletions(-)

Patch

diff --git a/init/Kconfig b/init/Kconfig
index 27890607e8cb..1e1c49f1d129 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1251,6 +1251,9 @@  config IMA_NS
 	  Allow the creation of IMA namespaces for each user namespace.
 	  Namespaced IMA enables having IMA features work separately
 	  in each IMA namespace.
+	  Currently, only the audit status flags are stored in the namespace,
+	  which allows the same file to be audited each time it is accessed
+	  in a new namespace.
 
 endif # NAMESPACES
 
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 28896d256e36..dd06e16c4e1c 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -282,7 +282,8 @@  int process_buffer_measurement(struct user_namespace *mnt_userns,
 			       int pcr, const char *func_data,
 			       bool buf_hash, u8 *digest, size_t digest_len);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
-			   const unsigned char *filename);
+			   const unsigned char *filename,
+			   struct ns_status *status);
 int ima_alloc_init_template(struct ima_event_data *event_data,
 			    struct ima_template_entry **entry,
 			    struct ima_template_desc *template_desc);
@@ -426,6 +427,9 @@  static inline void ima_free_modsig(struct modsig *modsig)
 }
 #endif /* CONFIG_IMA_APPRAISE_MODSIG */
 
+#define IMA_NS_STATUS_ACTIONS   IMA_AUDIT
+#define IMA_NS_STATUS_FLAGS     IMA_AUDITED
+
 int ima_ns_init(void);
 struct ima_namespace;
 int ima_init_namespace(struct ima_namespace *ns);
@@ -436,6 +440,10 @@  struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
 
 void free_ns_status_cache(struct ima_namespace *ns);
 
+unsigned long iint_flags(struct integrity_iint_cache *iint,
+			 struct ns_status *status);
+unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+			     struct ns_status *status, unsigned long flags);
 #else
 
 static inline struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
@@ -444,6 +452,19 @@  static inline struct ns_status *ima_get_ns_status(struct ima_namespace *ns,
 	return NULL;
 }
 
+static inline unsigned long iint_flags(struct integrity_iint_cache *iint,
+				       struct ns_status *status)
+{
+	return iint->flags;
+}
+
+static inline unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+					   struct ns_status *status,
+					   unsigned long flags)
+{
+	iint->flags = flags;
+	return flags;
+}
 #endif /* CONFIG_IMA_NS */
 
 /* LSM based policy rules require audit */
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index a64fb0130b01..8f7bab17b784 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -342,14 +342,16 @@  void ima_store_measurement(struct integrity_iint_cache *iint,
 }
 
 void ima_audit_measurement(struct integrity_iint_cache *iint,
-			   const unsigned char *filename)
+			   const unsigned char *filename,
+			   struct ns_status *status)
 {
 	struct audit_buffer *ab;
 	char *hash;
 	const char *algo_name = hash_algo_name[iint->ima_hash->algo];
 	int i;
+	unsigned long flags = iint_flags(iint, status);
 
-	if (iint->flags & IMA_AUDITED)
+	if (flags & IMA_AUDITED)
 		return;
 
 	hash = kzalloc((iint->ima_hash->length * 2) + 1, GFP_KERNEL);
@@ -372,7 +374,7 @@  void ima_audit_measurement(struct integrity_iint_cache *iint,
 	audit_log_task_info(ab);
 	audit_log_end(ab);
 
-	iint->flags |= IMA_AUDITED;
+	set_iint_flags(iint, status, flags | IMA_AUDITED);
 out:
 	kfree(hash);
 	return;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 465865412100..4386010a480e 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -202,8 +202,10 @@  static int process_measurement(struct file *file, const struct cred *cred,
 			       u32 secid, char *buf, loff_t size, int mask,
 			       enum ima_hooks func)
 {
+	struct ima_namespace *ns = get_current_ns();
 	struct inode *inode = file_inode(file);
 	struct integrity_iint_cache *iint = NULL;
+	struct ns_status *status = NULL;
 	struct ima_template_desc *template_desc = NULL;
 	char *pathbuf = NULL;
 	char filename[NAME_MAX];
@@ -216,6 +218,7 @@  static int process_measurement(struct file *file, const struct cred *cred,
 	bool violation_check;
 	enum hash_algo hash_algo;
 	unsigned int allowed_algos = 0;
+	unsigned long flags;
 
 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return 0;
@@ -244,6 +247,12 @@  static int process_measurement(struct file *file, const struct cred *cred,
 		iint = integrity_inode_get(inode);
 		if (!iint)
 			rc = -ENOMEM;
+
+		if (!rc && (action & IMA_NS_STATUS_ACTIONS)) {
+			status = ima_get_ns_status(ns, inode);
+			if (IS_ERR(status))
+				rc = PTR_ERR(status);
+		}
 	}
 
 	if (!rc && violation_check)
@@ -259,11 +268,13 @@  static int process_measurement(struct file *file, const struct cred *cred,
 
 	mutex_lock(&iint->mutex);
 
+	flags = iint_flags(iint, status);
+
 	if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
 		/* reset appraisal flags if ima_inode_post_setattr was called */
-		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
-				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
-				 IMA_ACTION_FLAGS);
+		flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
+			   IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
+			   IMA_ACTION_FLAGS);
 
 	/*
 	 * Re-evaulate the file if either the xattr has changed or the
@@ -274,7 +285,7 @@  static int process_measurement(struct file *file, const struct cred *cred,
 	    ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
 	     !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
 	     !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
-		iint->flags &= ~IMA_DONE_MASK;
+		flags &= ~IMA_DONE_MASK;
 		iint->measured_pcrs = 0;
 	}
 
@@ -282,9 +293,9 @@  static int process_measurement(struct file *file, const struct cred *cred,
 	 * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
 	 *  IMA_AUDIT, IMA_AUDITED)
 	 */
-	iint->flags |= action;
+	flags = set_iint_flags(iint, status, flags | action);
 	action &= IMA_DO_MASK;
-	action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
+	action &= ~((flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
 
 	/* If target pcr is already measured, unset IMA_MEASURE action */
 	if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
@@ -359,7 +370,7 @@  static int process_measurement(struct file *file, const struct cred *cred,
 						  &pathname, filename);
 	}
 	if (action & IMA_AUDIT)
-		ima_audit_measurement(iint, pathname);
+		ima_audit_measurement(iint, pathname, status);
 
 	if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
 		rc = 0;
diff --git a/security/integrity/ima/ima_ns.c b/security/integrity/ima/ima_ns.c
index e21e9e0d2316..000dbde2f264 100644
--- a/security/integrity/ima/ima_ns.c
+++ b/security/integrity/ima/ima_ns.c
@@ -66,6 +66,26 @@  void free_ima_ns(struct kref *kref)
 	destroy_ima_ns(ns);
 }
 
+unsigned long iint_flags(struct integrity_iint_cache *iint,
+			 struct ns_status *status)
+{
+	if (!status)
+		return iint->flags;
+
+	return (iint->flags & ~IMA_NS_STATUS_FLAGS) |
+	       (status->flags & IMA_NS_STATUS_FLAGS);
+}
+
+unsigned long set_iint_flags(struct integrity_iint_cache *iint,
+			     struct ns_status *status, unsigned long flags)
+{
+	iint->flags = flags;
+	if (status)
+		status->flags = flags & IMA_NS_STATUS_FLAGS;
+
+	return flags;
+}
+
 static int __init imans_cache_init(void)
 {
 	imans_cachep = KMEM_CACHE(ima_namespace, SLAB_PANIC);