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Date: Thu, 10 Sep 2015 08:28:09 -0500
From: "Serge E. Hallyn" <serge@hallyn.com>
To: David Drysdale <drysdale@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
        Andy Lutomirski <luto@amacapital.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: RFC: fsyscall
Message-ID: <20150910132809.GA27602@mail.hallyn.com>
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On Wed, Sep 09, 2015 at 06:27:06PM +0100, David Drysdale wrote:
> On Wed, Sep 9, 2015 at 1:25 AM, Eric W. Biederman <ebiederm@xmission.com> wrote:
> > Andy Lutomirski <luto@amacapital.net> writes:
> > > On Tue, Sep 8, 2015 at 4:07 PM, Eric W. Biederman <ebiederm@xmission.com> wrote:
>
> (From this perspective, the limitation that seccomp-bpf programs only
> have access to syscall arguments by-value is actually a help -- the filter
> can't look into user memory, so can't be fooled by having memory
> contents changed underneath it.  Of course, if the eBPF stuff ever
> changes that we should watch out...)

Yup and I'm quite sure I've seen that raised as a reason to refuse
supporting exactly that.