ima: handle idmapped mounts

IMA does sometimes access the inode's i_uid and compares it against the
rules' fowner. Enable IMA to handle idmapped mounts by passing down the
mount's user namespace. We simply make use of the helpers we introduced
before. If the initial user namespace is passed nothing changes so
non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-27-christian.brauner@ubuntu.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

1 files changed, 12 insertions, 7 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 8e8b1e3cb847..b87c9006d577 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -253,8 +253,9 @@ static inline void ima_process_queued_keys(void) {}
 #endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */
 
 /* LIM API function definitions */
-int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
-		   int mask, enum ima_hooks func, int *pcr,
+int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
+		   const struct cred *cred, u32 secid, int mask,
+		   enum ima_hooks func, int *pcr,
 		   struct ima_template_desc **template_desc,
 		   const char *keyring);
 int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
@@ -266,7 +267,8 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
 			   struct evm_ima_xattr_data *xattr_value,
 			   int xattr_len, const struct modsig *modsig, int pcr,
 			   struct ima_template_desc *template_desc);
-void process_buffer_measurement(struct inode *inode, const void *buf, int size,
+void process_buffer_measurement(struct user_namespace *mnt_userns,
+				struct inode *inode, const void *buf, int size,
 				const char *eventname, enum ima_hooks func,
 				int pcr, const char *keyring);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
@@ -281,8 +283,9 @@ void ima_free_template_entry(struct ima_template_entry *entry);
 const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);
 
 /* IMA policy related functions */
-int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid,
-		     enum ima_hooks func, int mask, int flags, int *pcr,
+int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
+		     const struct cred *cred, u32 secid, enum ima_hooks func,
+		     int mask, int flags, int *pcr,
 		     struct ima_template_desc **template_desc,
 		     const char *keyring);
 void ima_init_policy(void);
@@ -313,7 +316,8 @@ int ima_appraise_measurement(enum ima_hooks func,
 			     struct file *file, const unsigned char *filename,
 			     struct evm_ima_xattr_data *xattr_value,
 			     int xattr_len, const struct modsig *modsig);
-int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func);
+int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
+		      int mask, enum ima_hooks func);
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
 					   enum ima_hooks func);
@@ -340,7 +344,8 @@ static inline int ima_appraise_measurement(enum ima_hooks func,
 	return INTEGRITY_UNKNOWN;
 }
 
-static inline int ima_must_appraise(struct inode *inode, int mask,
+static inline int ima_must_appraise(struct user_namespace *mnt_userns,
+				    struct inode *inode, int mask,
 				    enum ima_hooks func)
 {
 	return 0;