fs: port xattr to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

7 files changed, 36 insertions, 35 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 03b440921e61..d8530e722515 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -254,7 +254,7 @@ static inline void ima_process_queued_keys(void) {}
 #endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */
 
 /* LIM API function definitions */
-int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_get_action(struct mnt_idmap *idmap, struct inode *inode,
 		   const struct cred *cred, u32 secid, int mask,
 		   enum ima_hooks func, int *pcr,
 		   struct ima_template_desc **template_desc,
@@ -268,7 +268,7 @@ 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);
-int process_buffer_measurement(struct user_namespace *mnt_userns,
+int process_buffer_measurement(struct mnt_idmap *idmap,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
@@ -285,7 +285,7 @@ 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 user_namespace *mnt_userns, struct inode *inode,
+int ima_match_policy(struct mnt_idmap *idmap, 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,
@@ -318,7 +318,7 @@ 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 user_namespace *mnt_userns, struct inode *inode,
+int ima_must_appraise(struct mnt_idmap *idmap, 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,
@@ -346,7 +346,7 @@ static inline int ima_appraise_measurement(enum ima_hooks func,
 	return INTEGRITY_UNKNOWN;
 }
 
-static inline int ima_must_appraise(struct user_namespace *mnt_userns,
+static inline int ima_must_appraise(struct mnt_idmap *idmap,
 				    struct inode *inode, int mask,
 				    enum ima_hooks func)
 {
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index c1e76282b5ee..9345fd66f5b8 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -163,7 +163,7 @@ err_out:
 
 /**
  * ima_get_action - appraise & measure decision based on policy.
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: pointer to the inode associated with the object being validated
  * @cred: pointer to credentials structure to validate
  * @secid: secid of the task being validated
@@ -186,7 +186,7 @@ err_out:
  * Returns IMA_MEASURE, IMA_APPRAISE mask.
  *
  */
-int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_get_action(struct mnt_idmap *idmap, struct inode *inode,
 		   const struct cred *cred, u32 secid, int mask,
 		   enum ima_hooks func, int *pcr,
 		   struct ima_template_desc **template_desc,
@@ -196,7 +196,7 @@ int ima_get_action(struct user_namespace *mnt_userns, struct inode *inode,
 
 	flags &= ima_policy_flag;
 
-	return ima_match_policy(mnt_userns, inode, cred, secid, func, mask,
+	return ima_match_policy(idmap, inode, cred, secid, func, mask,
 				flags, pcr, template_desc, func_data,
 				allowed_algos);
 }
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 734a6818a545..4078a9ad8531 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -70,7 +70,7 @@ bool is_ima_appraise_enabled(void)
  *
  * Return 1 to appraise or hash
  */
-int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_must_appraise(struct mnt_idmap *idmap, struct inode *inode,
 		      int mask, enum ima_hooks func)
 {
 	u32 secid;
@@ -79,7 +79,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
 		return 0;
 
 	security_current_getsecid_subj(&secid);
-	return ima_match_policy(mnt_userns, inode, current_cred(), secid,
+	return ima_match_policy(idmap, inode, current_cred(), secid,
 				func, mask, IMA_APPRAISE | IMA_HASH, NULL,
 				NULL, NULL, NULL);
 }
@@ -98,7 +98,7 @@ static int ima_fix_xattr(struct dentry *dentry,
 		iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG;
 		iint->ima_hash->xattr.ng.algo = algo;
 	}
-	rc = __vfs_setxattr_noperm(&init_user_ns, dentry, XATTR_NAME_IMA,
+	rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_IMA,
 				   &iint->ima_hash->xattr.data[offset],
 				   (sizeof(iint->ima_hash->xattr) - offset) +
 				   iint->ima_hash->length, 0);
@@ -456,7 +456,7 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
 
 		rc = is_binary_blacklisted(digest, digestsize);
 		if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
-			process_buffer_measurement(&init_user_ns, NULL, digest, digestsize,
+			process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize,
 						   "blacklisted-hash", NONE,
 						   pcr, NULL, false, NULL, 0);
 	}
@@ -622,7 +622,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 
 /**
  * ima_inode_post_setattr - reflect file metadata changes
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:  idmap of the mount the inode was found from
  * @dentry: pointer to the affected dentry
  *
  * Changes to a dentry's metadata might result in needing to appraise.
@@ -630,7 +630,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
  * This function is called from notify_change(), which expects the caller
  * to lock the inode's i_mutex.
  */
-void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+void ima_inode_post_setattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry)
 {
 	struct inode *inode = d_backing_inode(dentry);
@@ -641,7 +641,7 @@ void ima_inode_post_setattr(struct user_namespace *mnt_userns,
 	    || !(inode->i_opflags & IOP_XATTR))
 		return;
 
-	action = ima_must_appraise(mnt_userns, inode, MAY_ACCESS, POST_SETATTR);
+	action = ima_must_appraise(idmap, inode, MAY_ACCESS, POST_SETATTR);
 	iint = integrity_iint_find(inode);
 	if (iint) {
 		set_bit(IMA_CHANGE_ATTR, &iint->atomic_flags);
diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index f6aa0b47a772..caacfe6860b1 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -60,7 +60,7 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 	 * if the IMA policy is configured to measure a key linked
 	 * to the given keyring.
 	 */
-	process_buffer_measurement(&init_user_ns, NULL, payload, payload_len,
+	process_buffer_measurement(&nop_mnt_idmap, NULL, payload, payload_len,
 				   keyring->description, KEY_CHECK, 0,
 				   keyring->description, false, NULL, 0);
 }
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 377300973e6c..358578267fea 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -224,7 +224,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	 * bitmask based on the appraise/audit/measurement policy.
 	 * Included is the appraise submask.
 	 */
-	action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid,
+	action = ima_get_action(file_mnt_idmap(file), inode, cred, secid,
 				mask, func, &pcr, &template_desc, NULL,
 				&allowed_algos);
 	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
@@ -451,7 +451,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
 
 	security_current_getsecid_subj(&secid);
 	inode = file_inode(vma->vm_file);
-	action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
+	action = ima_get_action(file_mnt_idmap(vma->vm_file), inode,
 				current_cred(), secid, MAY_EXEC, MMAP_CHECK,
 				&pcr, &template, NULL, NULL);
 
@@ -638,14 +638,14 @@ EXPORT_SYMBOL_GPL(ima_inode_hash);
 
 /**
  * ima_post_create_tmpfile - mark newly created tmpfile as new
- * @mnt_userns: user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: inode of the newly created tmpfile
  *
  * No measuring, appraising or auditing of newly created tmpfiles is needed.
  * Skip calling process_measurement(), but indicate which newly, created
  * tmpfiles are in policy.
  */
-void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 			     struct inode *inode)
 {
 	struct integrity_iint_cache *iint;
@@ -654,7 +654,7 @@ void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return;
 
-	must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
+	must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS,
 					  FILE_CHECK);
 	if (!must_appraise)
 		return;
@@ -671,13 +671,13 @@ void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
 
 /**
  * ima_post_path_mknod - mark as a new inode
- * @mnt_userns: user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @dentry: newly created dentry
  *
  * Mark files created via the mknodat syscall as new, so that the
  * file data can be written later.
  */
-void ima_post_path_mknod(struct user_namespace *mnt_userns,
+void ima_post_path_mknod(struct mnt_idmap *idmap,
 			 struct dentry *dentry)
 {
 	struct integrity_iint_cache *iint;
@@ -687,7 +687,7 @@ void ima_post_path_mknod(struct user_namespace *mnt_userns,
 	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
 		return;
 
-	must_appraise = ima_must_appraise(mnt_userns, inode, MAY_ACCESS,
+	must_appraise = ima_must_appraise(idmap, inode, MAY_ACCESS,
 					  FILE_CHECK);
 	if (!must_appraise)
 		return;
@@ -869,7 +869,7 @@ int ima_post_load_data(char *buf, loff_t size,
 
 /**
  * process_buffer_measurement - Measure the buffer or the buffer data hash
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: inode associated with the object being measured (NULL for KEY_CHECK)
  * @buf: pointer to the buffer that needs to be added to the log.
  * @size: size of buffer(in bytes).
@@ -887,7 +887,7 @@ int ima_post_load_data(char *buf, loff_t size,
  * has been written to the passed location but not added to a measurement entry,
  * a negative value otherwise.
  */
-int process_buffer_measurement(struct user_namespace *mnt_userns,
+int process_buffer_measurement(struct mnt_idmap *idmap,
 			       struct inode *inode, const void *buf, int size,
 			       const char *eventname, enum ima_hooks func,
 			       int pcr, const char *func_data,
@@ -931,7 +931,7 @@ int process_buffer_measurement(struct user_namespace *mnt_userns,
 	 */
 	if (func) {
 		security_current_getsecid_subj(&secid);
-		action = ima_get_action(mnt_userns, inode, current_cred(),
+		action = ima_get_action(idmap, inode, current_cred(),
 					secid, 0, func, &pcr, &template,
 					func_data, NULL);
 		if (!(action & IMA_MEASURE) && !digest)
@@ -1011,7 +1011,7 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
 	if (!f.file)
 		return;
 
-	process_buffer_measurement(file_mnt_user_ns(f.file), file_inode(f.file),
+	process_buffer_measurement(file_mnt_idmap(f.file), file_inode(f.file),
 				   buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
 				   NULL, false, NULL, 0);
 	fdput(f);
@@ -1044,7 +1044,7 @@ int ima_measure_critical_data(const char *event_label,
 	if (!event_name || !event_label || !buf || !buf_len)
 		return -ENOPARAM;
 
-	return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
+	return process_buffer_measurement(&nop_mnt_idmap, NULL, buf, buf_len,
 					  event_name, CRITICAL_DATA, 0,
 					  event_label, hash, digest,
 					  digest_len);
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 6a68ec270822..2ba72bc5d9c2 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -552,7 +552,7 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
 /**
  * ima_match_rules - determine whether an inode matches the policy rule.
  * @rule: a pointer to a rule
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: a pointer to an inode
  * @cred: a pointer to a credentials structure for user validation
  * @secid: the secid of the task to be validated
@@ -563,7 +563,7 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
  * Returns true on rule match, false on failure.
  */
 static bool ima_match_rules(struct ima_rule_entry *rule,
-			    struct user_namespace *mnt_userns,
+			    struct mnt_idmap *idmap,
 			    struct inode *inode, const struct cred *cred,
 			    u32 secid, enum ima_hooks func, int mask,
 			    const char *func_data)
@@ -572,6 +572,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
 	bool result = false;
 	struct ima_rule_entry *lsm_rule = rule;
 	bool rule_reinitialized = false;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 
 	if ((rule->flags & IMA_FUNC) &&
 	    (rule->func != func && func != POST_SETATTR))
@@ -713,7 +714,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
 
 /**
  * ima_match_policy - decision based on LSM and other conditions
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: pointer to an inode for which the policy decision is being made
  * @cred: pointer to a credentials structure for which the policy decision is
  *        being made
@@ -732,7 +733,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
  * list when walking it.  Reads are many orders of magnitude more numerous
  * than writes so ima_match_policy() is classical RCU candidate.
  */
-int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
+int ima_match_policy(struct mnt_idmap *idmap, 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,
@@ -752,7 +753,7 @@ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode,
 		if (!(entry->action & actmask))
 			continue;
 
-		if (!ima_match_rules(entry, mnt_userns, inode, cred, secid,
+		if (!ima_match_rules(entry, idmap, inode, cred, secid,
 				     func, mask, func_data))
 			continue;
 
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index 93056c03bf5a..4f0aea155bf9 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -159,7 +159,7 @@ void ima_process_queued_keys(void)
 
 	list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
 		if (!timer_expired)
-			process_buffer_measurement(&init_user_ns, NULL,
+			process_buffer_measurement(&nop_mnt_idmap, NULL,
 						   entry->payload,
 						   entry->payload_len,
 						   entry->keyring_name,