From: Lennart Poettering <lennart@poettering.net>
To: Paul Moore <paul@paul-moore.com>
Cc: "Kees Cook" <keescook@chromium.org>,
"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>,
"Tom Hromatka" <tom.hromatka@oracle.com>
Subject: Re: new seccomp mode aims to improve performance
Date: Tue, 2 Jun 2020 14:53:23 +0200 [thread overview]
Message-ID: <20200602125323.GB123838@gardel-login> (raw)
In-Reply-To: <CAHC9VhTK1306C2+ghMWHC0X6XVHiG+vBKPC5=7QLjxXwX4Eu9Q@mail.gmail.com>
On Mo, 01.06.20 08:32, Paul Moore (paul@paul-moore.com) wrote:
> In situations where the calling application creates multiple per-ABI
> filters, the seccomp_merge(3) function can be used to merge the
> filters into one. There are some limitations (same byte ordering,
> filter attributes, etc.) but in general it should work without problem
> when merging x86_64, x32, and x86.
Hmm, so we currently only use seccomp_rule_add_exact() to build an
individual filter and finally seccomp_load() to install it. Which
tells us exactly what works and what does not.
If we now would use seccomp_rule_add_exact() to build the filters, but
then use seccomp_merge() to merge them all, and then only do a single
seccomp_load(), will this give us the same info? i.e. will
seccomp_merge() give us the same errors seccomp_load() currently gives
us when something cannot work?
> > If we wanted to optimize that in userspace, then libseccomp would have
> > to be improved quite substantially to let us know exactly what works
> > and what doesn't, and to have sane fallback both when building
> > whitelists and blacklists.
>
> It has been quite a while since we last talked about systemd's use of
> libseccomp, but the upcoming v2.5.0 release (no date set yet, but
> think weeks not months) finally takes a first step towards defining
> proper return values on error for the API, no more "negative values on
> error". I'm sure there are other things, but I recall this as being
> one of the bigger systemd wants.
Yes, we care about error codes a lot.
> As an aside, it is always going to be difficult to allow fine grained
> control when you have a single libseccomp filter that includes
> multiple ABIs; the different ABI oddities are just too great (see
> comments above). If you need exacting control of the filter, or ABI
> specific handling, then the recommended way is to create those filters
> independently and merge them together before loading them into the
> kernel or applying any common rules.
Hmm, so not sure I got this. But are you saying that when using
seccomp_merge() am I supposed to merge filters for different archs
into one megafilter, or are you saying the opposite: am I supposed not
to do that?
I.e. in an ideal world, should we come to a situation where per
service on x86-64 we will have exactly one filter installed, or should
we come to a situation where we'll have exactly three installed, once
for each ABI?
Lennart
--
Lennart Poettering, Berlin
next prev parent reply other threads:[~2020-06-02 12:53 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 [this message]
2020-06-02 15:03 ` Paul Moore
2020-06-02 18:39 ` Kees Cook
2020-06-01 18:21 ` Kees Cook
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=20200602125323.GB123838@gardel-login \
--to=lennart@poettering.net \
--cc=alexei.starovoitov@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=christian.ehrhardt@canonical.com \
--cc=hehuazhen@huawei.com \
--cc=keescook@chromium.org \
--cc=linux-security-module@vger.kernel.org \
--cc=paul@paul-moore.com \
--cc=tom.hromatka@oracle.com \
--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).