[PATCH 5.5 348/367] cifs: fix mode bits from dir listing when mounted with modefromsid

Greg Kroah-Hartman
2020-02-10T12:47:19Z

From: Aurelien Aptel <aaptel@suse.com>

commit e3e056c35108661e418c803adfc054bf683426e7 upstream.

When mounting with -o modefromsid, the mode bits are stored in an
ACE. Directory enumeration (e.g. ls -l /mnt) triggers an SMB Query Dir
which does not include ACEs in its response. The mode bits in this
case are silently set to a default value of 755 instead.

This patch marks the dentry created during the directory enumeration
as needing re-evaluation (i.e. additional Query Info with ACEs) so
that the mode bits can be properly extracted.

Quick repro:

$ mount.cifs //win19.test/data /mnt -o ...,modefromsid
$ touch /mnt/foo && chmod 751 /mnt/foo
$ stat /mnt/foo
# reports 751 (OK)
$ sleep 2
# dentry older than 1s by default get invalidated
$ ls -l /mnt
# since dentry invalid, ls does a Query Dir
# and reports foo as 755 (WRONG)

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/readdir.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -196,7 +196,8 @@ cifs_fill_common_info(struct cifs_fattr
* may look wrong since the inodes may not have timed out by the time
* "ls" does a stat() call on them.
*/
- if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL)
+ if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) ||
+ (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MODE_FROM_SID))
fattr->cf_flags |= CIFS_FATTR_NEED_REVAL;

if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL &&