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From: Kees Cook <keescook@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "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>
Subject: Re: new seccomp mode aims to improve performance
Date: Fri, 29 May 2020 09:09:28 -0700
Message-ID: <202005290903.11E67AB0FD@keescook> (raw)
In-Reply-To: <CAADnVQLnFuOR+Xk1QXpLFGHx-8StPCye7j5UgKbBoLrmKtygQA@mail.gmail.com>

On Fri, May 29, 2020 at 08:43:56AM -0700, Alexei Starovoitov wrote:
> On Fri, May 29, 2020 at 5:50 AM zhujianwei (C) <zhujianwei7@huawei.com> wrote:
> >
> > Hi, all
> >
> >   We're using seccomp to increase container security, but bpf rules filter causes performance to deteriorate. So, is there a good solution to improve performance, or can we add a simplified seccomp mode to improve performance?

Yes, there are already plans for a simple syscall bitmap[1] seccomp feature.

> I don't think your hunch at where cpu is spending cycles is correct.
> Could you please do two experiments:
> 1. try trivial seccomp bpf prog that simply returns 'allow'
> 2. replace bpf_prog_run_pin_on_cpu() in seccomp.c with C code
>   that returns 'allow' and make sure it's noinline or in a different C file,
>   so that compiler doesn't optimize the whole seccomp_run_filters() into a nop.
> 
> Then measure performance of both.
> I bet you'll see exactly the same numbers.

Android has already done this, it appeared to not be the same. Calling
into a SECCOMP_RET_ALLOW filter had a surprisingly high cost. I'll see
if I can get you the numbers. I was frankly quite surprised -- I
understood the bulk of the seccomp overhead to be in taking the TIF_WORK
path, copying arguments, etc, but something else is going on there.

-Kees

[1] https://lore.kernel.org/lkml/202005181120.971232B7B@keescook/

-- 
Kees Cook

  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29 12:48 zhujianwei (C)
2020-05-29 15:43 ` Alexei Starovoitov
2020-05-29 16:09   ` Kees Cook [this message]
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
2020-06-02 12:44           ` Lennart Poettering
2020-06-02 18:37             ` Kees Cook
2020-06-16  6:00             ` Kees Cook

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