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Date: Tue, 20 Sep 2011 08:47:37 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
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Subject: [kernel-hardening] Re: [Security] [PATCH 2/2] taskstats: restrict access to user
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Vasiliy Kulikov <segoon@openwall.com>, Balbir Singh <bsingharora@gmail.com>, Shailabh Nagar <nagar@us.ibm.com>, linux-kernel@vger.kernel.org, security@kernel.org, Eric Paris <eparis@redhat.com>, Stephen Wilson <wilsons@start.ca>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, David Rientjes <rientjes@google.com>, Andrew Morton <akpm@linux-foundation.org>, Balbir Singh <balbir@linux.vnet.ibm.com>, kernel-hardening@lists.openwall.com
List-ID: <kernel-hardening.lists.openwall.com>

On Mon, Sep 19, 2011 at 10:45:20AM -0700, Linus Torvalds wrote:
> On Mon, Sep 19, 2011 at 10:39 AM, Vasiliy Kulikov <segoon@openwall.com> wrote:
> >
> > Shouldn't it simply protect taskstats_user_cmd()?  You may still poll
> > the counters with TASKSTATS_CMD_ATTR_PID/TASKSTATS_CMD_ATTR_TGID.
> 
> Yeah, I wondered where I'd really want to hook it in, that was the
> other option.
> 
> However, one thing that I'm currently independently asking some
> networking people is whether that patch guarantees anything at all: is
> the netlink command even guaranteed to be run in the same context as
> the person sending it?
> 
> After all, it comes in as a packet of data.  How synchronous is the
> genetlink thing guaranteed to be in the first place?
> 
> IOW, are *any* of those "check current capabilities/euid" approaches
> really guaranteed to be valid? Are they valid today, will they
> necessarily be valid in a year?

Netlink was made syncronous by commit cd40b7d3983c708aabe3d3008ec64ffce56d33b0
"[NET]: make netlink user -> kernel interface synchronious".