linux-kernel - Re: [RFC] fs, proc: Introduce /proc/<pid>/task/<tid>/children entry v5

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20120115184806.GA25928@redhat.com>
Date:	Sun, 15 Jan 2012 19:48:06 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Tejun Heo <tj@...nel.org>, Andrew Vagin <avagin@...nvz.org>,
	Vasiliy Kulikov <segoon@...nwall.com>
Subject: Re: [RFC] fs, proc: Introduce /proc/<pid>/task/<tid>/children
	entry v5

On 01/15, Cyrill Gorcunov wrote:
>
> On Sun, Jan 15, 2012 at 07:07:21PM +0100, Oleg Nesterov wrote:
> >
> > Again. I simply can't understand what ptrace_may_access() actually
> > means. Why do we use the possible child, not parent?
> >
> > IOW. I have no idea if we really need any security check at all.
> > You can find the children pids without this patch anyway via.
> > grep PPid /proc/*/status.
> >
>
> OK, I see. I am actually not sure which behaviour should be there.
> What should we do if say we have a task with a number of children,
> which changed permissions of own and some of children. Look what I mean.
>
> We have say tid A, which has children B C D, and when we read
> /proc/pid/task/tid/children we should see "B C D" here. But
> what if say A started with roots rights, then changed own permission
> so everyone could read this /proc/pid/task/<A>/children, but
> left C with root permissions only. So should we list C here?

Why not? What is the problem to know the pid of this child? And once
again, you can list all children without this patch anyway.

Perhaps I missed something, but I simply don't understand the problem.

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/