From: Oleg Nesterov <oleg@redhat.com>
To: Amnon Shiloh <u3557@miso.sublimeip.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
Chris Evans <scarybeasts@gmail.com>,
David Howells <dhowells@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Andrew Morton <akpm@linux-foundation.org>,
u3557@dialix.com.au, security@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: PT_EXITKILL (Was: pdeath_signal)
Date: Thu, 8 Nov 2012 13:37:16 +0100 [thread overview]
Message-ID: <20121108123716.GA20917@redhat.com> (raw)
In-Reply-To: <20121108062935.BFF3A592024@miso.sublimeip.com>
Hi Amnon,
On 11/08, Amnon Shiloh wrote:
>
> Thanks for the patch, I tried it and it works nicely!
OK, thanks. I'll wait for other comments a bit and then send
the patch to Andrew.
> Also, I just noticed that this new option (PTRACE_O_EXITKILL) is not
> safe with ptrace(PTRACE_TRACEME)+execve, because the parent may die
> before even having a chance to set PTRACE_O_EXITKILL!
Not safe? I guess you meant that PTRACE_O_EXITKILL can't prevent
this race? Yes sure. Or the parent can die before it does
PTRACE_O_EXITKILL.
> However, that's easy to fix by using PTRACE_ATTACH instead.
Or the child can check getppid() == saved_parent_pid after PTRACE_TRACEME.
But if you switch to PTRACE_ATTACH, I'd suggest to use PTRACE_SEIZE.
Note that, in particular, this allows you to specify the options at
attach.
As for PF_NO_SIGSTOP, I'll write another email.
Oleg.
next prev parent reply other threads:[~2012-11-08 12:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20121106152050.GA18218@sergelap>
[not found] ` <20121106201428.9D72959201A@miso.sublimeip.com>
2012-11-07 15:09 ` Oleg Nesterov
2012-11-08 6:29 ` Amnon Shiloh
2012-11-08 12:37 ` Oleg Nesterov [this message]
2012-11-08 13:03 ` Amnon Shiloh
2012-11-18 20:21 ` [PATCH 0/1] ptrace: introduce PTRACE_O_EXITKILL Oleg Nesterov
2012-11-18 20:21 ` [PATCH 1/1] " Oleg Nesterov
2012-11-08 12:48 ` PF_NO_SIGSTOP (Was: PT_EXITKILL) Oleg Nesterov
2012-11-08 14:05 ` Amnon Shiloh
2012-11-08 12:16 ` PT_EXITKILL (Was: pdeath_signal) Pedro Alves
2012-11-08 12:44 ` Oleg Nesterov
2012-11-08 13:00 ` Pedro Alves
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