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Date: Wed, 27 Apr 2011 22:43:04 -0500
Message-ID: <BANLkTikfM+WAjgWEcaift+3=fd0z3FkprQ@mail.gmail.com>
Subject: Re: [PATCH 4/7] seccomp_filter: add process state reporting
From: Will Drewry <wad@chromium.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        linux-kernel@vger.kernel.org, kees.cook@canonical.com,
        eparis@redhat.com, agl@chromium.org, mingo@elte.hu, jmorris@namei.org,
        rostedt@goodmis.org, Andrew Morton <akpm@linux-foundation.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        David Howells <dhowells@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Stephen Wilson <wilsons@start.ca>
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On Wed, Apr 27, 2011 at 10:40 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Wed, Apr 27, 2011 at 10:24:20PM -0500, Will Drewry wrote:
>
>> Definitely. ?Would it make sense to have /proc/<pid>/seccomp and
>> /proc/<pid>/seccomp_filter?
>
> Just one question: WTF bother with S_IRUSR? ?Note that it's absolutely
> _useless_ in procfs; any kind of permission checks must be done in
> read(2) time since doing it in open(2) is worthless. ?Consider execve()
> on suid binary; oops, there goes your uid and there goes the effect
> of checks done by open(2). ?And if you *do* checks in read(2), why bother
> duplicating them in open(2)?

In earlier versions I was allowing filter/bitmask updating via the
proc file (which I nixed :).  Is S_IRUGO preferred? I don't see any
crazy information leakage by sharing the filters/ruleset.  I'll fold
it into the next version of this patch.

thanks!
will
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