From: ebiederm@xmission.com (Eric W. Biederman)
To: Jeff Layton <jlayton@redhat.com>
Cc: Jamie Lokier <jamie@shareable.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-nfs@vger.kernel.org, adobriyan@gmail.com,
viro@ZenIV.linux.org.uk
Subject: Re: [PATCH] proc: revalidate dentry returned by proc_pid_follow_link
Date: Sun, 08 Nov 2009 19:30:55 -0800 [thread overview]
Message-ID: <m1hbt49xxs.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20091108201237.79af5cac@tupile.poochiereds.net> (Jeff Layton's message of "Sun\, 8 Nov 2009 20\:12\:37 -0500")
Jeff Layton <jlayton@redhat.com> writes:
>> Hmm. Looking at the code I get the impression that a file bind mount
>> will have exactly the same problem.
>>
>> Can you confirm.
>>
>> If file bind mounts also have this problem a bugfix to to just
>> proc seems questionable.
>>
>
> I'm not sure I understand what you mean by "file bind mount". Is that
> something like mounting with "-o loop" ?
# cd /tmp
# echo foo > foo
# echo bar > bar
# mount --bind foo bar
# cat bar
foo
#
> I'm not at all opposed to fixing this in a more broad fashion, but as
> best I can tell, the only place that LAST_BIND is used is in procfs.
proc does appear to be the only user of LAST_BIND. With a file bind
mount we can get to the same ok: label without a revalidate. The
difference is that we came from __follow_mount instead of follow_link.
At least that is how I read the code.
Eric
next prev parent reply other threads:[~2009-11-09 3:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-06 13:19 [PATCH] proc: revalidate dentry returned by proc_pid_follow_link Jeff Layton
2009-11-06 20:36 ` Jamie Lokier
2009-11-06 21:06 ` Jeff Layton
2009-11-08 10:15 ` Eric W. Biederman
2009-11-09 1:12 ` Jeff Layton
2009-11-09 3:30 ` Eric W. Biederman [this message]
2009-11-09 13:11 ` Jeff Layton
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