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>

1 files changed, 10 insertions, 12 deletions

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,