From: Herbert Poetzl <herbert@13thfloor.at>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: Albert Cahalan <albert@users.sf.net>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>,
cw@f00f.org, mingo@elte.hu, anton@samba.org
Subject: Re: /proc/sys/kernel/pid_max issues
Date: Mon, 13 Sep 2004 16:51:48 +0200 [thread overview]
Message-ID: <20040913145148.GD1774@MAIL.13thfloor.at> (raw)
In-Reply-To: <20040913142752.GC9106@holomorphy.com>
On Mon, Sep 13, 2004 at 07:27:52AM -0700, William Lee Irwin III wrote:
> On Mon, 2004-09-13 at 03:42, William Lee Irwin III wrote:
> >> The resource tracking and locking implications of this are disturbing.
> >> Would fully pseudorandom allocation be acceptable?
>
> On Mon, Sep 13, 2004 at 10:11:29AM -0400, Albert Cahalan wrote:
> > There's no point.
> > LRU reduces accidents that don't involve an attacker.
> > Strong crypto random can make some attacks a bit harder.
> > OpenBSD does this. It doesn't work well enough to bother
> > with if the implementation is problematic; there's not
> > much you can do while avoiding 64-bit or 128-bit PIDs.
> > Pseudorandom is 100% useless.
> > Per-user PID recycling would make it much harder for
> > an attacker to grab a specific PID. Perhaps the attacker
> > knows that a sched_setscheduler call is coming, and he
> > has a way to make the right process restart or crash.
> > Normally, this lets him get SCHED_FIFO or somesuch.
> > With per-user PID recycling, it would be difficult for
> > him to grab the desired PID.
>
> I'd suggest pushing for 64-bit+ pid's, then. IIRC most of the work
> there is in userspace (the in-kernel part is trivial).
except for the various 'assumptions' done in procfs
to create the inode numbers ... but that is a different
story ...
best,
Herbert
> -- wli
> -
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next prev parent reply other threads:[~2004-09-13 15:07 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-13 3:20 /proc/sys/kernel/pid_max issues Albert Cahalan
2004-09-13 7:42 ` William Lee Irwin III
2004-09-13 14:11 ` Albert Cahalan
2004-09-13 14:27 ` William Lee Irwin III
2004-09-13 14:51 ` Herbert Poetzl [this message]
2004-09-14 2:13 ` William Lee Irwin III
2004-09-23 13:13 ` Pavel Machek
2004-09-24 16:02 ` Martin Mares
2004-09-23 13:11 ` Pavel Machek
2004-09-13 7:57 ` Ingo Molnar
2004-09-13 13:54 ` Albert Cahalan
2004-09-13 14:24 ` William Lee Irwin III
2004-09-13 14:54 ` Albert Cahalan
2004-09-14 2:02 ` William Lee Irwin III
2004-09-14 15:32 ` Ingo Molnar
2004-09-18 18:32 ` Pavel Machek
2004-09-23 13:18 ` Pavel Machek
-- strict thread matches above, loose matches on Subject: below --
2004-09-12 8:56 Anton Blanchard
2004-09-12 9:36 ` William Lee Irwin III
2004-09-12 9:51 ` Ingo Molnar
2004-09-12 9:58 ` William Lee Irwin III
2004-09-12 10:10 ` William Lee Irwin III
2004-09-12 10:13 ` Ingo Molnar
2004-09-12 10:43 ` William Lee Irwin III
2004-09-12 10:45 ` William Lee Irwin III
2004-09-12 11:08 ` William Lee Irwin III
2004-09-12 11:20 ` Ingo Molnar
2004-09-12 17:13 ` William Lee Irwin III
2004-09-12 18:02 ` Chris Wedgwood
2004-09-12 23:06 ` William Lee Irwin III
2004-09-12 9:39 ` Ingo Molnar
2004-09-12 9:43 ` William Lee Irwin III
2004-09-12 12:18 ` Arjan van de Ven
2004-09-12 12:30 ` Anton Blanchard
2004-09-12 12:44 ` Arjan van de Ven
2004-09-12 13:34 ` Anton Blanchard
2004-09-12 13:41 ` Ingo Molnar
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