From: Kees Cook <keescook@chromium.org>
To: Lennart Poettering <lennart@poettering.net>
Cc: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>,
"zhujianwei (C)" <zhujianwei7@huawei.com>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
Hehuazhen <hehuazhen@huawei.com>,
"Christian Ehrhardt" <christian.ehrhardt@canonical.com>,
"Zbigniew Jędrzejewski-Szmek" <zbyszek@in.waw.pl>
Subject: Re: new seccomp mode aims to improve performance
Date: Mon, 1 Jun 2020 11:21:25 -0700 [thread overview]
Message-ID: <202006011116.3F7109A@keescook> (raw)
In-Reply-To: <20200601101137.GA121847@gardel-login>
On Mon, Jun 01, 2020 at 12:11:37PM +0200, Lennart Poettering wrote:
> On Fr, 29.05.20 12:27, Kees Cook (keescook@chromium.org) wrote:
>
> > # grep ^Seccomp_filters /proc/$(pidof systemd-resolved)/status
> > Seccomp_filters: 32
> >
> > # grep SystemCall /lib/systemd/system/systemd-resolved.service
> > SystemCallArchitectures=native
> > SystemCallErrorNumber=EPERM
> > SystemCallFilter=@system-service
> >
> > I'd like to better understand what they're doing, but haven't had time
> > to dig in. (The systemd devel mailing list requires subscription, so
> > I've directly CCed some systemd folks that have touched seccomp there
> > recently. Hi! The starts of this thread is here[4].)
>
> Hmm, so on x86-64 we try to install our seccomp filters three times:
> for the x86-64 syscall ABI, for the i386 syscall ABI and for the x32
> syscall ABI. Not all of the filters we apply work on all ABIs though,
> because syscalls are available on some but not others, or cannot
> sensibly be matched on some (because of socketcall, ipc and such
> multiplexed syscalls).
>
> [...]
Thanks for the details on this! That helps me understand what's
happening much better. :)
> An easy improvement is probably if libseccomp would now start refusing
> to install x32 seccomp filters altogether now that x32 is entirely
> dead? Or are the entrypoints for x32 syscalls still available in the
> kernel? How could userspace figure out if they are available? If
> libseccomp doesn't want to add code for that, we probably could have
> that in systemd itself too...
Would it make sense to provide a systemd setting for services to declare
"no compat" or "no x32" (I'm not sure what to call this mode more
generically, "no 32-bit allocation ABI"?) Then you can just install
a single merged filter for all the native syscalls that starts with
"if not native, reject"?
(Or better yet: make the default for filtering be "native only", and
let services opt into other ABIs?)
--
Kees Cook
next prev parent reply other threads:[~2020-06-01 18:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-29 12:48 new seccomp mode aims to improve performance zhujianwei (C)
2020-05-29 15:43 ` Alexei Starovoitov
2020-05-29 16:09 ` Kees Cook
2020-05-29 17:31 ` Alexei Starovoitov
2020-05-29 19:27 ` Kees Cook
2020-05-31 17:19 ` Alexei Starovoitov
2020-06-01 18:16 ` Kees Cook
2020-06-01 2:08 ` 答复: " zhujianwei (C)
2020-06-01 3:30 ` Alexei Starovoitov
2020-06-02 2:42 ` 答复: " zhujianwei (C)
2020-06-02 3:24 ` Alexei Starovoitov
2020-06-02 11:13 ` 答复: " zhujianwei (C)
2020-06-02 11:34 ` zhujianwei (C)
2020-06-02 18:32 ` Kees Cook
2020-06-03 4:51 ` 答复: " zhujianwei (C)
2020-06-01 10:11 ` Lennart Poettering
2020-06-01 12:32 ` Paul Moore
2020-06-02 12:53 ` Lennart Poettering
2020-06-02 15:03 ` Paul Moore
2020-06-02 18:39 ` Kees Cook
2020-06-01 18:21 ` Kees Cook [this message]
2020-06-02 12:44 ` Lennart Poettering
2020-06-02 18:37 ` Kees Cook
2020-06-16 6:00 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202006011116.3F7109A@keescook \
--to=keescook@chromium.org \
--cc=alexei.starovoitov@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=christian.ehrhardt@canonical.com \
--cc=hehuazhen@huawei.com \
--cc=lennart@poettering.net \
--cc=linux-security-module@vger.kernel.org \
--cc=zbyszek@in.waw.pl \
--cc=zhujianwei7@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).