Re: [PATCH v2 00/10] userns: sysctl limits for namespaces

From	"Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 00/10] userns: sysctl limits for namespaces
Date	2016-07-26 19:30 +0200
Message-ID	<rZel3-4VT-3@gated-at.bofh.it> (permalink)
References	<rXpuj-1Dd-53@gated-at.bofh.it> <rXpuh-1Dd-3@gated-at.bofh.it> <rZ7Wh-Od-23@gated-at.bofh.it> <rZcsW-3C5-11@gated-at.bofh.it> <rZdS2-4t5-21@gated-at.bofh.it>
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On 26 July 2016 at 18:52, Kees Cook <keescook@chromium.org> wrote:
> On Tue, Jul 26, 2016 at 8:06 AM, Eric W. Biederman
> <ebiederm@xmission.com> wrote:
>> "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> writes:
>>
>>> Hello Eric,
>>>
>>> I realized I had a question after the last mail.
>>>
>>> On 07/21/2016 06:39 PM, Eric W. Biederman wrote:
>>>>
>>>> This patchset addresses two use cases:
>>>> - Implement a sane upper bound on the number of namespaces.
>>>> - Provide a way for sandboxes to limit the attack surface from
>>>>   namespaces.
>>>
>>> Can you say more about the second point? What exactly is the
>>> problem that is being addressed, and how does the patch series
>>> address it? (It would be good to have those details in the
>>> revised commit message...)
>>
>> At some point it was reported that seccomp was not sufficient to disable
>> namespace creation.  I need to go back and look at that claim to see
>> which set of circumstances that was referring to.  Seccomp doesn't stack
>> so I can see why it is an issue.
>
> seccomp does stack. The trouble usually comes from a perception that
> seccomp overhead is not trivial, so setting a system-wide policy is a
> bit of a large hammer for such a limitiation. Also, at the time,
> seccomp could be bypasses with ptrace, but this (as of v4.8) is no
> longer true.

Sounds like someone needs to send me a patch for the seccomp.2 man page?

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

Thread

Re: [PATCH v2 00/10] userns: sysctl limits for namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-26 12:40 +0200
  Re: [PATCH v2 00/10] userns: sysctl limits for namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-26 17:30 +0200
    Re: [PATCH v2 00/10] userns: sysctl limits for namespaces Kees Cook <keescook@chromium.org> - 2016-07-26 19:00 +0200
      Re: [PATCH v2 00/10] userns: sysctl limits for namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-26 19:30 +0200
        Re: [PATCH v2 00/10] userns: sysctl limits for namespaces Kees Cook <keescook@chromium.org> - 2016-07-26 22:50 +0200

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