[PATCH] cifs: fix mode bits from dir listing when mounted with modefromsid

[PATCH] cifs: fix mode bits from dir listing when mounted with modefromsid

[Aurelien Aptel]

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

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index d17587c2c4ab..ba9dadf3be24 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -196,7 +196,8 @@ cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
 	 * 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 &&
-- 
2.16.4

Re: [PATCH] cifs: fix mode bits from dir listing when mounted with modefromsid

[Pavel Shilovsky]

чт, 6 февр. 2020 г. в 09:17, Aurelien Aptel <aaptel@suse.com>:
>
> 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>
> ---
>  fs/cifs/readdir.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
> index d17587c2c4ab..ba9dadf3be24 100644
> --- a/fs/cifs/readdir.c
> +++ b/fs/cifs/readdir.c
> @@ -196,7 +196,8 @@ cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
>          * 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 &&
> --
> 2.16.4
>

Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

This patch needs stable tag since "modefromsid" was introduced in v5.5.

--
Best regards,
Pavel Shilovsky

Re: [PATCH] cifs: fix mode bits from dir listing when mounted with modefromsid

[Steve French]

I added stable already - will add your reviewed by as well. thx

On Thu, Feb 6, 2020 at 12:24 PM Pavel Shilovsky <piastryyy@gmail.com> wrote:
>
> чт, 6 февр. 2020 г. в 09:17, Aurelien Aptel <aaptel@suse.com>:
> >
> > 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>
> > ---
> >  fs/cifs/readdir.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
> > index d17587c2c4ab..ba9dadf3be24 100644
> > --- a/fs/cifs/readdir.c
> > +++ b/fs/cifs/readdir.c
> > @@ -196,7 +196,8 @@ cifs_fill_common_info(struct cifs_fattr *fattr, struct cifs_sb_info *cifs_sb)
> >          * 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 &&
> > --
> > 2.16.4
> >
>
> Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
>
> This patch needs stable tag since "modefromsid" was introduced in v5.5.
>
> --
> Best regards,
> Pavel Shilovsky



-- 
Thanks,

Steve