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From:   Pradeep <pradeepthomas@gmail.com>
Date:   Fri, 4 Sep 2020 11:09:00 -0700
Message-ID: <CAD8zhTD7mPjiUkRn_crywXDNP2kWGpMc8M4QFTG1T9eihuz9XQ@mail.gmail.com>
Subject: Re: Wrong mode bits in stat of NFSv4 referral directories.
To:     Benjamin Coddington <bcodding@redhat.com>, bjschuma@netapp.com,
        Trond.Myklebust@netapp.com
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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Thanks Benjamin. Looks like it is added as part of commit
72de53ec4bca39c26709122a8f78bfefe7b6bca4 by Bryan Schumaker.

Given that neither chmod nor readdir traverses the referral mount
points, wouldn't this be an issue to return mode bits as 0555?
The issue I see is with rsync. rsync first creates the directory and
calls chmod. If this directory happens to be a referral mount, then
chmod fails because the user doesn't have write access (0555).

Thanks

On Fri, Sep 4, 2020 at 10:15 AM Benjamin Coddington <bcodding@redhat.com> w=
rote:
>
> Probably in nfs_fixup_secinfo_attributes(), and looks deliberate.  I'm no=
t
> sure about the reasoning behind it, though.  Maybe it's to clarify that y=
ou
> can't traverse this directory.
>
> Ben
>
> On 4 Sep 2020, at 12:57, Pradeep wrote:
>
> > Just to add, if you look at packet 100 (READDIR response) in tcpdump,
> > the mode bits are set to 0755. But what is displayed by "ls" is 0555.
> > I'm trying to figure out where that one bit gets lost.
> >
> > On Fri, Sep 4, 2020 at 8:55 AM Pradeep <pradeepthomas@gmail.com> wrote:
> >>
> >> Hello,
> >>
> >> I'm seeing an issue where stat (and ls) reports wrong mode bits on
> >> referral directories. Actual permissions are 755; but Linux client
> >> displays 555. This causes some operations like setattr (chmod) to
> >> fail. Traversing to the directory fixes the issue.
> >>
> >> Kernel version : 5.8.6-2.el7.elrepo.x86_64
> >>
> >> [nfstest@centos77 ~]$ mkdir /mnt/nfsh1/dir.{1..5}
> >> [nfstest@centos77 ~]$ ls -l /mnt/nfsh1
> >> total 3
> >> dr-xr-xr-x. 2 nfstest wheel 2 Sep  3 17:55 dir.1
> >> drwxr-xr-x. 2 nfstest wheel 2 Sep  3 17:55 dir.2
> >> dr-xr-xr-x. 2 nfstest wheel 2 Sep  3 17:55 dir.3
> >> dr-xr-xr-x. 2 nfstest wheel 2 Sep  3 17:55 dir.4
> >> dr-xr-xr-x. 2 nfstest wheel 2 Sep  3 17:55 dir.5
> >> [nfstest@centos77 ~]$ stat /mnt/nfsh1/dir.1
> >>   File: =E2=80=98/mnt/nfsh1/dir.1=E2=80=99
> >>   Size: 2               Blocks: 1          IO Block: 1048576 directory
> >> Device: 30h/48d Inode: 3940649673949864  Links: 2
> >> Access: (0555/dr-xr-xr-x)  Uid: ( 2000/ nfstest)   Gid: (   10/   whee=
l)
> >> Context: system_u:object_r:nfs_t:s0
> >> Access: 2020-09-03 17:55:59.082327209 -0400
> >> Modify: 2020-09-03 17:55:59.082327209 -0400
> >> Change: 2020-09-03 17:55:59.082327209 -0400
> >>  Birth: -
> >> [nfstest@centos77 ~]$ ls /mnt/nfsh1/dir.1  <-- Try traversing into the
> >> dir, see the mode bits in stat after traversal.
> >> [nfstest@centos77 ~]$ stat /mnt/nfsh1/dir.1
> >>   File: =E2=80=98/mnt/nfsh1/dir.1=E2=80=99
> >>   Size: 2               Blocks: 1          IO Block: 32768  directory
> >> Device: 32h/50d Inode: 3940649673949864  Links: 2
> >> Access: (0755/drwxr-xr-x)  Uid: ( 2000/ nfstest)   Gid: (   10/   whee=
l)
> >> Context: system_u:object_r:nfs_t:s0
> >> Access: 2020-09-03 17:55:59.082327209 -0400
> >> Modify: 2020-09-03 17:55:59.082327209 -0400
> >> Change: 2020-09-03 17:55:59.082327209 -0400
> >>  Birth: -
> >>
> >> Attached is the tcpdump for requests. It looks like the server sends
> >> back correct attributes; but the client somehow is ignoring it. Any
> >> ideas why?
> >>
> >> Thanks,
> >> Pradeep
>