netdev - Re: 2.6.24-rc3: find complains about /proc/net

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 20 Nov 2007 17:41:35 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Ulrich Drepper <drepper@...hat.com>
Cc:	Roland McGrath <roland@...hat.com>,
	Guillaume Chazarain <guichaz@...oo.fr>,
	Ingo Molnar <mingo@...e.hu>,
	Pavel Emelyanov <xemul@...nvz.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Pavel Machek <pavel@....cz>,
	kernel list <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: 2.6.24-rc3: find complains about /proc/net

Ulrich Drepper <drepper@...hat.com> writes:

> Roland McGrath wrote:
>> Oh, it seems it has indeed been that way for a very long time, so I was
>> mistaken.  It still seems a little odd to me.  Ulrich can say definitively
>> whether the kind of concern I mentioned really matters one way or the other
>> for glibc.
>
> glibc cannot survive (at least NPTL) if somebody uses funny CLONE_*
> flags to separate various pieces of information, e.g., file descriptors.
>  So, all the information in each thread's /proc/self should be identical.

Which seems to confirm that glibc and native pthread can't care.

> When the information is not the same, the current semantics seems to be
> more useful.  So I guess, no change is the way to go here.

Could you elaborate a bit on how the semantics of returning the
wrong information are more useful?

In particular if a thread does the logical equivalent of:
grep Pid: /proc/self/status.  It always get the tgid despite
having a different process id.

How can that possibly be useful or correct?

>From the kernel side I really think the current semantics of /proc/self
in the context of threads is a bug and confusing.  All of the kernel
developers first reaction when this was pointed out was that this
is a regression.

If it is truly useful to user space we can preserve this API design
bug forever.  I just want to make certain we are not being bug
compatible without a good reason.

Currently we have several kernel side bugs with threaded
programs because /proc/self does not do the intuitive thing.  Unless
something has changed recently selinux will cause accesses by a
non-leader thread to fail when accessing files through /proc/self.

So far the more I look at the current /proc/self behavior the
more I am convinced it is broken, and useless.  Please help me see
where it is useful, so we can justify keeping it.

Thanks,
Eric
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html