Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <cover.1600661418.git.yifeifz2@illinois.edu> <b792335294ee5598d0fb42702a49becbce2f925f.1600661419.git.yifeifz2@illinois.edu>
 <CAG48ez3k0_7Vev_O=uV_WVuUGK6BPA0RyrYXMYSDV4DTMMe26g@mail.gmail.com>
 <CABqSeAROcwq0ZGzWaxyPm+LDHu6T_8CD7_1c-hdhaMikr_ECCA@mail.gmail.com> <CAG48ez2HytqFaJ6V9iA6YZrbZU3kG4bB7nETMfHPt0-wd5D1jg@mail.gmail.com>
In-Reply-To: <CAG48ez2HytqFaJ6V9iA6YZrbZU3kG4bB7nETMfHPt0-wd5D1jg@mail.gmail.com>
From:   YiFei Zhu <zhuyifei1999@gmail.com>
Date:   Mon, 21 Sep 2020 18:08:00 -0500
Message-ID: <CABqSeAQDpJZdAD42myca=3BAGAJ9VyDjvEiXfcH+p3m4eo_vBw@mail.gmail.com>
Subject: Re: [RFC PATCH seccomp 2/2] seccomp/cache: Cache filter results that
 allow syscalls
To:     Jann Horn <jannh@google.com>
Cc:     Linux Containers <containers@lists.linux-foundation.org>,
        YiFei Zhu <yifeifz2@illinois.edu>, bpf <bpf@vger.kernel.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Dimitrios Skarlatos <dskarlat@cs.cmu.edu>,
        Giuseppe Scrivano <gscrivan@redhat.com>,
        Hubertus Franke <frankeh@us.ibm.com>,
        Jack Chen <jianyan2@illinois.edu>,
        Josep Torrellas <torrella@illinois.edu>,
        Kees Cook <keescook@chromium.org>,
        Tianyin Xu <tyxu@illinois.edu>,
        Tobin Feldman-Fitzthum <tobin@ibm.com>,
        Valentin Rothberg <vrothber@redhat.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Will Drewry <wad@chromium.org>,
        Aleksa Sarai <cyphar@cyphar.com>,
        kernel list <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Sep 21, 2020 at 5:58 PM Jann Horn <jannh@google.com> wrote:
> > I do agree that an immutable bitmask is faster and easier to reason
> > about its correctness. However, I did not find the "code to statically
> > evaluate the filter for all syscall numbers" while reading seccomp.c.
> > Would you give me a pointer to that and I will see how to best make
> > use of it?
>
> I'm talking about the code you're adding in the other patch ("[RFC
> PATCH seccomp 1/2] seccomp/cache: Add "emulator" to check if filter is
> arg-dependent"). Sorry, that was a bit unclear.

I see, building an immutable accept bitmask when preparing and then
just use that when running it. I guess if the arch number issue is
resolved this should be more doable. Will do.

YiFei Zhu