fs: port inode_owner_or_capable() 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, 9 insertions, 9 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index f49496087102..b0dc7212694e 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -358,12 +358,12 @@ void ext4_reset_inode_seed(struct inode *inode)
  * important fields of the inodes.
  *
  * @sb:         the super block of the filesystem
- * @mnt_userns:	user namespace of the mount the inode was found from
+ * @idmap:	idmap of the mount the inode was found from
  * @inode:      the inode to swap with EXT4_BOOT_LOADER_INO
  *
  */
 static long swap_inode_boot_loader(struct super_block *sb,
-				struct user_namespace *mnt_userns,
+				struct mnt_idmap *idmap,
 				struct inode *inode)
 {
 	handle_t *handle;
@@ -393,7 +393,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
 	}
 
 	if (IS_RDONLY(inode) || IS_APPEND(inode) || IS_IMMUTABLE(inode) ||
-	    !inode_owner_or_capable(mnt_userns, inode) ||
+	    !inode_owner_or_capable(idmap, inode) ||
 	    !capable(CAP_SYS_ADMIN)) {
 		err = -EPERM;
 		goto journal_err_out;
@@ -1217,7 +1217,7 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct inode *inode = file_inode(filp);
 	struct super_block *sb = inode->i_sb;
-	struct user_namespace *mnt_userns = file_mnt_user_ns(filp);
+	struct mnt_idmap *idmap = file_mnt_idmap(filp);
 
 	ext4_debug("cmd = %u, arg = %lu\n", cmd, arg);
 
@@ -1234,7 +1234,7 @@ static long __ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		__u32 generation;
 		int err;
 
-		if (!inode_owner_or_capable(mnt_userns, inode))
+		if (!inode_owner_or_capable(idmap, inode))
 			return -EPERM;
 
 		if (ext4_has_metadata_csum(inode->i_sb)) {
@@ -1376,7 +1376,7 @@ mext_out:
 	case EXT4_IOC_MIGRATE:
 	{
 		int err;
-		if (!inode_owner_or_capable(mnt_userns, inode))
+		if (!inode_owner_or_capable(idmap, inode))
 			return -EACCES;
 
 		err = mnt_want_write_file(filp);
@@ -1398,7 +1398,7 @@ mext_out:
 	case EXT4_IOC_ALLOC_DA_BLKS:
 	{
 		int err;
-		if (!inode_owner_or_capable(mnt_userns, inode))
+		if (!inode_owner_or_capable(idmap, inode))
 			return -EACCES;
 
 		err = mnt_want_write_file(filp);
@@ -1417,7 +1417,7 @@ mext_out:
 		err = mnt_want_write_file(filp);
 		if (err)
 			return err;
-		err = swap_inode_boot_loader(sb, mnt_userns, inode);
+		err = swap_inode_boot_loader(sb, idmap, inode);
 		mnt_drop_write_file(filp);
 		return err;
 	}
@@ -1542,7 +1542,7 @@ resizefs_out:
 
 	case EXT4_IOC_CLEAR_ES_CACHE:
 	{
-		if (!inode_owner_or_capable(mnt_userns, inode))
+		if (!inode_owner_or_capable(idmap, inode))
 			return -EACCES;
 		ext4_clear_inode_es(inode);
 		return 0;