From: Luis R. Rodriguez <mcgrof@kernel.org>
Date: Sun, 13 May 2018 20:45:56 +0000 (-0400)
Subject: ext4: add verifier check for symlink with append/immutable flags
X-Git-Tag: v4.18-rc1~143^2~13
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6390d33bf5d9b24fd4f96e415b6888f59c8494f9;p=thirdparty%2Flinux.git

ext4: add verifier check for symlink with append/immutable flags

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>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
---

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0eb64e8f96025..9d512fa80d28c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4965,6 +4965,13 @@ 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);