diff mbox

[RFC,v2,3/4] ext4: add verifier check for symlink with append/immutable flags

Message ID 20180510231359.16899-4-mcgrof@kernel.org
State New, archived
Headers show

Commit Message

Luis Chamberlain May 10, 2018, 11:13 p.m. UTC
The Linux VFS does not allow a way to set append/immuttable
attributes to symlinks, this is just not possible. If this is
detected inform the user as the filesystem must be corrupted.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 fs/ext4/inode.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Jan Kara May 11, 2018, 9:12 p.m. UTC | #1
On Thu 10-05-18 16:13:58, Luis R. Rodriguez wrote:
> The Linux VFS does not allow a way to set append/immuttable
> attributes to symlinks, this is just not possible. If this is
> detected inform the user as the filesystem must be corrupted.
> 
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/ext4/inode.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 37a2f7a2b66a..6acf0dd6b6e6 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4947,6 +4947,13 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
>  		inode->i_op = &ext4_dir_inode_operations;
>  		inode->i_fop = &ext4_dir_operations;
>  	} else if (S_ISLNK(inode->i_mode)) {
> +		/* VFS does not allow setting these so must be corruption */
> +		if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
> +			EXT4_ERROR_INODE(inode,
> +			  "immutable or append flags not allowed on symlinks");
> +			ret = -EFSCORRUPTED;
> +			goto bad_inode;
> +		}
>  		if (ext4_encrypted_inode(inode)) {
>  			inode->i_op = &ext4_encrypted_symlink_inode_operations;
>  			ext4_set_aops(inode);
> -- 
> 2.17.0
>
Theodore Y. Ts'o May 13, 2018, 8:51 p.m. UTC | #2
On Fri, May 11, 2018 at 11:12:18PM +0200, Jan Kara wrote:
> On Thu 10-05-18 16:13:58, Luis R. Rodriguez wrote:
> > The Linux VFS does not allow a way to set append/immuttable
> > attributes to symlinks, this is just not possible. If this is
> > detected inform the user as the filesystem must be corrupted.
> > 
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> 
> Looks good to me. You can add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>

Applied into the ext4 tree after verifying that e2fsck already handles
this case:

% e2fsck -fy /tmp/foo.img
e2fsck 1.44.1 (24-Mar-2018)
Pass 1: Checking inodes, blocks, and sizes
Special (device/socket/fifo/symlink) file (inode 13) has immutable
or append-only flag set.  Clear? yes

(The btrfs and xfs maintainers might want to make a similar check
before accepting their respective patches.)

						- Ted
diff mbox

Patch

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 37a2f7a2b66a..6acf0dd6b6e6 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4947,6 +4947,13 @@  struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 		inode->i_op = &ext4_dir_inode_operations;
 		inode->i_fop = &ext4_dir_operations;
 	} else if (S_ISLNK(inode->i_mode)) {
+		/* VFS does not allow setting these so must be corruption */
+		if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
+			EXT4_ERROR_INODE(inode,
+			  "immutable or append flags not allowed on symlinks");
+			ret = -EFSCORRUPTED;
+			goto bad_inode;
+		}
 		if (ext4_encrypted_inode(inode)) {
 			inode->i_op = &ext4_encrypted_symlink_inode_operations;
 			ext4_set_aops(inode);