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, 31 insertions, 32 deletions

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 65efb74c3585..0a8ba82ef1af 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -42,6 +42,7 @@ struct inode;
 struct dentry;
 struct task_struct;
 struct user_namespace;
+struct mnt_idmap;
 
 extern const kernel_cap_t __cap_empty_set;
 extern const kernel_cap_t __cap_init_eff_set;
@@ -271,11 +272,11 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
 }
 
 /* audit system wants to get cap info from files as well */
-int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
+int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 			   const struct dentry *dentry,
 			   struct cpu_vfs_cap_data *cpu_caps);
 
-int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
+int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const void **ivalue, size_t size);
 
 #endif /* !_LINUX_CAPABILITY_H */
diff --git a/include/linux/evm.h b/include/linux/evm.h
index 1f8f806dd0d1..e06aacd3e315 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -24,14 +24,14 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
 extern int evm_inode_setattr(struct mnt_idmap *idmap,
 			     struct dentry *dentry, struct iattr *attr);
 extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
-extern int evm_inode_setxattr(struct user_namespace *mnt_userns,
+extern int evm_inode_setxattr(struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *name,
 			      const void *value, size_t size);
 extern void evm_inode_post_setxattr(struct dentry *dentry,
 				    const char *xattr_name,
 				    const void *xattr_value,
 				    size_t xattr_value_len);
-extern int evm_inode_removexattr(struct user_namespace *mnt_userns,
+extern int evm_inode_removexattr(struct mnt_idmap *idmap,
 				 struct dentry *dentry, const char *xattr_name);
 extern void evm_inode_post_removexattr(struct dentry *dentry,
 				       const char *xattr_name);
@@ -101,7 +101,7 @@ static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
 	return;
 }
 
-static inline int evm_inode_setxattr(struct user_namespace *mnt_userns,
+static inline int evm_inode_setxattr(struct mnt_idmap *idmap,
 				     struct dentry *dentry, const char *name,
 				     const void *value, size_t size)
 {
@@ -116,7 +116,7 @@ static inline void evm_inode_post_setxattr(struct dentry *dentry,
 	return;
 }
 
-static inline int evm_inode_removexattr(struct user_namespace *mnt_userns,
+static inline int evm_inode_removexattr(struct mnt_idmap *idmap,
 					struct dentry *dentry,
 					const char *xattr_name)
 {
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 5a0b2a285a18..6f470b658082 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -18,7 +18,7 @@ struct linux_binprm;
 extern enum hash_algo ima_get_current_hash_algo(void);
 extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask);
-extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+extern void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 				    struct inode *inode);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
@@ -30,7 +30,7 @@ extern int ima_read_file(struct file *file, enum kernel_read_file_id id,
 			 bool contents);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 			      enum kernel_read_file_id id);
-extern void ima_post_path_mknod(struct user_namespace *mnt_userns,
+extern void ima_post_path_mknod(struct mnt_idmap *idmap,
 				struct dentry *dentry);
 extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
 extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size);
@@ -66,7 +66,7 @@ static inline int ima_file_check(struct file *file, int mask)
 	return 0;
 }
 
-static inline void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
+static inline void ima_post_create_tmpfile(struct mnt_idmap *idmap,
 					   struct inode *inode)
 {
 }
@@ -111,7 +111,7 @@ static inline int ima_post_read_file(struct file *file, void *buf, loff_t size,
 	return 0;
 }
 
-static inline void ima_post_path_mknod(struct user_namespace *mnt_userns,
+static inline void ima_post_path_mknod(struct mnt_idmap *idmap,
 				       struct dentry *dentry)
 {
 	return;
@@ -183,7 +183,7 @@ static inline void ima_post_key_create_or_update(struct key *keyring,
 
 #ifdef CONFIG_IMA_APPRAISE
 extern bool is_ima_appraise_enabled(void);
-extern void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+extern void ima_inode_post_setattr(struct mnt_idmap *idmap,
 				   struct dentry *dentry);
 extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
 		       const void *xattr_value, size_t xattr_value_len);
@@ -203,7 +203,7 @@ static inline bool is_ima_appraise_enabled(void)
 	return 0;
 }
 
-static inline void ima_inode_post_setattr(struct user_namespace *mnt_userns,
+static inline void ima_inode_post_setattr(struct mnt_idmap *idmap,
 					  struct dentry *dentry)
 {
 	return;
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 894f233083e3..f344c0e7387a 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -136,14 +136,14 @@ LSM_HOOK(int, 0, inode_follow_link, struct dentry *dentry, struct inode *inode,
 LSM_HOOK(int, 0, inode_permission, struct inode *inode, int mask)
 LSM_HOOK(int, 0, inode_setattr, struct dentry *dentry, struct iattr *attr)
 LSM_HOOK(int, 0, inode_getattr, const struct path *path)
-LSM_HOOK(int, 0, inode_setxattr, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_setxattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name, const void *value,
 	 size_t size, int flags)
 LSM_HOOK(void, LSM_RET_VOID, inode_post_setxattr, struct dentry *dentry,
 	 const char *name, const void *value, size_t size, int flags)
 LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
-LSM_HOOK(int, 0, inode_removexattr, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_set_acl, struct user_namespace *mnt_userns,
 	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
@@ -152,7 +152,7 @@ LSM_HOOK(int, 0, inode_get_acl, struct user_namespace *mnt_userns,
 LSM_HOOK(int, 0, inode_remove_acl, struct user_namespace *mnt_userns,
 	 struct dentry *dentry, const char *acl_name)
 LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
-LSM_HOOK(int, 0, inode_killpriv, struct user_namespace *mnt_userns,
+LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap,
 	 struct dentry *dentry)
 LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
 	 struct inode *inode, const char *name, void **buffer, bool alloc)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 0a5ba81f7367..6e156d2acffc 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -475,7 +475,7 @@
  * @inode_killpriv:
  *	The setuid bit is being removed.  Remove similar security labels.
  *	Called with the dentry->d_inode->i_mutex held.
- *	@mnt_userns: user namespace of the mount.
+ *	@idmap: idmap of the mount.
  *	@dentry is the dentry being changed.
  *	Return 0 on success.  If error is returned, then the operation
  *	causing setuid bit removal is failed.
diff --git a/include/linux/security.h b/include/linux/security.h
index d9cd7b2d16a2..474373e631df 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -153,11 +153,10 @@ extern int cap_capset(struct cred *new, const struct cred *old,
 extern int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file);
 int cap_inode_setxattr(struct dentry *dentry, const char *name,
 		       const void *value, size_t size, int flags);
-int cap_inode_removexattr(struct user_namespace *mnt_userns,
+int cap_inode_removexattr(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *name);
 int cap_inode_need_killpriv(struct dentry *dentry);
-int cap_inode_killpriv(struct user_namespace *mnt_userns,
-		       struct dentry *dentry);
+int cap_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int cap_inode_getsecurity(struct mnt_idmap *idmap,
 			  struct inode *inode, const char *name, void **buffer,
 			  bool alloc);
@@ -359,7 +358,7 @@ int security_inode_permission(struct inode *inode, int mask);
 int security_inode_setattr(struct mnt_idmap *idmap,
 			   struct dentry *dentry, struct iattr *attr);
 int security_inode_getattr(const struct path *path);
-int security_inode_setxattr(struct user_namespace *mnt_userns,
+int security_inode_setxattr(struct mnt_idmap *idmap,
 			    struct dentry *dentry, const char *name,
 			    const void *value, size_t size, int flags);
 int security_inode_set_acl(struct user_namespace *mnt_userns,
@@ -373,11 +372,10 @@ void security_inode_post_setxattr(struct dentry *dentry, const char *name,
 				  const void *value, size_t size, int flags);
 int security_inode_getxattr(struct dentry *dentry, const char *name);
 int security_inode_listxattr(struct dentry *dentry);
-int security_inode_removexattr(struct user_namespace *mnt_userns,
+int security_inode_removexattr(struct mnt_idmap *idmap,
 			       struct dentry *dentry, const char *name);
 int security_inode_need_killpriv(struct dentry *dentry);
-int security_inode_killpriv(struct user_namespace *mnt_userns,
-			    struct dentry *dentry);
+int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int security_inode_getsecurity(struct mnt_idmap *idmap,
 			       struct inode *inode, const char *name,
 			       void **buffer, bool alloc);
@@ -874,7 +872,7 @@ static inline int security_inode_getattr(const struct path *path)
 	return 0;
 }
 
-static inline int security_inode_setxattr(struct user_namespace *mnt_userns,
+static inline int security_inode_setxattr(struct mnt_idmap *idmap,
 		struct dentry *dentry, const char *name, const void *value,
 		size_t size, int flags)
 {
@@ -918,11 +916,11 @@ static inline int security_inode_listxattr(struct dentry *dentry)
 	return 0;
 }
 
-static inline int security_inode_removexattr(struct user_namespace *mnt_userns,
+static inline int security_inode_removexattr(struct mnt_idmap *idmap,
 					     struct dentry *dentry,
 					     const char *name)
 {
-	return cap_inode_removexattr(mnt_userns, dentry, name);
+	return cap_inode_removexattr(idmap, dentry, name);
 }
 
 static inline int security_inode_need_killpriv(struct dentry *dentry)
@@ -930,10 +928,10 @@ static inline int security_inode_need_killpriv(struct dentry *dentry)
 	return cap_inode_need_killpriv(dentry);
 }
 
-static inline int security_inode_killpriv(struct user_namespace *mnt_userns,
+static inline int security_inode_killpriv(struct mnt_idmap *idmap,
 					  struct dentry *dentry)
 {
-	return cap_inode_killpriv(mnt_userns, dentry);
+	return cap_inode_killpriv(idmap, dentry);
 }
 
 static inline int security_inode_getsecurity(struct mnt_idmap *idmap,
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index b39d156e0098..6af72461397d 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -42,7 +42,7 @@ struct xattr_handler {
 		   struct inode *inode, const char *name, void *buffer,
 		   size_t size);
 	int (*set)(const struct xattr_handler *,
-		   struct user_namespace *mnt_userns, struct dentry *dentry,
+		   struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct inode *inode, const char *name, const void *buffer,
 		   size_t size, int flags);
 };
@@ -59,16 +59,16 @@ ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, si
 ssize_t vfs_getxattr(struct mnt_idmap *, struct dentry *, const char *,
 		     void *, size_t);
 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
-int __vfs_setxattr(struct user_namespace *, struct dentry *, struct inode *,
+int __vfs_setxattr(struct mnt_idmap *, struct dentry *, struct inode *,
 		   const char *, const void *, size_t, int);
-int __vfs_setxattr_noperm(struct user_namespace *, struct dentry *,
+int __vfs_setxattr_noperm(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int);
 int __vfs_setxattr_locked(struct mnt_idmap *, struct dentry *,
 			  const char *, const void *, size_t, int,
 			  struct inode **);
 int vfs_setxattr(struct mnt_idmap *, struct dentry *, const char *,
 		 const void *, size_t, int);
-int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
+int __vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
 int __vfs_removexattr_locked(struct mnt_idmap *, struct dentry *,
 			     const char *, struct inode **);
 int vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);