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Re: [PATCH] userns/capability: Add user namespace capability

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Am 18.10.2015 um 22:13 schrieb Tobias Markus:
> On 17.10.2015 22:17, Richard Weinberger wrote:
>> On Sat, Oct 17, 2015 at 5:58 PM, Tobias Markus <tobias@miglix.eu> wrote:
>>> One question remains though: Does this break userspace executables that
>>> expect being able to create user namespaces without priviledge? Since
>>> creating user namespaces without CAP_SYS_ADMIN was not possible before
>>> Linux 3.8, programs should already expect a potential EPERM upon calling
>>> clone. Since creating a user namespace without CAP_SYS_USER_NS would
>>> also cause EPERM, we should be on the safe side.
>>
>> In case of doubt, yes it will break existing software.
>> Hiding user namespaces behind CAP_SYS_USER_NS will not magically
>> make them secure.
>>
> The goal is not to make user namespaces secure, but to limit access to
> them somewhat in order to reduce the potential attack surface.

We have already a framework to reduce the attack surface, seccomp.
There is no need to invent new capabilities for every non-trivial
kernel feature.

I can understand the user namespaces seems scary and had bugs.
But which software didn't?

Are there any unfixed exploitable bugs in user namespaces in recent kerenls?

Thanks,
//richard

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[PATCH] userns/capability: Add user namespace capability Tobias Markus <tobias@miglix.eu> - 2015-10-17 18:10 +0200
  Re: [PATCH] userns/capability: Add user namespace capability Richard Weinberger <richard.weinberger@gmail.com> - 2015-10-17 22:20 +0200
    Re: [PATCH] userns/capability: Add user namespace capability Tobias Markus <tobias@miglix.eu> - 2015-10-18 22:20 +0200
      Re: [PATCH] userns/capability: Add user namespace capability Richard Weinberger <richard@nod.at> - 2015-10-18 22:30 +0200
        Re: [PATCH] userns/capability: Add user namespace capability Tobias Markus <tobias@miglix.eu> - 2015-10-18 22:50 +0200
          Re: [PATCH] userns/capability: Add user namespace capability Richard Weinberger <richard@nod.at> - 2015-10-18 22:50 +0200
            Re: [PATCH] userns/capability: Add user namespace capability Tobias Markus <tobias@miglix.eu> - 2015-10-19 00:00 +0200
              Re: [PATCH] userns/capability: Add user namespace capability Richard Weinberger <richard@nod.at> - 2015-10-19 00:10 +0200
      Re: [PATCH] userns/capability: Add user namespace capability Mike Frysinger <vapier@gentoo.org> - 2015-10-19 02:30 +0200
  Re: [PATCH] userns/capability: Add user namespace capability "Serge E. Hallyn" <serge@hallyn.com> - 2015-10-18 00:00 +0200
    Re: [PATCH] userns/capability: Add user namespace capability Tobias Markus <tobias@miglix.eu> - 2015-10-18 22:20 +0200
      Re: [PATCH] userns/capability: Add user namespace capability "Serge E. Hallyn" <serge@hallyn.com> - 2015-10-19 03:50 +0200
        Re: [PATCH] userns/capability: Add user namespace capability Yves-Alexis Perez <corsac@debian.org> - 2015-10-19 14:40 +0200
          Re: [PATCH] userns/capability: Add user namespace capability Richard Weinberger <richard@nod.at> - 2015-10-19 14:50 +0200
      Re: [PATCH] userns/capability: Add user namespace capability ebiederm@xmission.com (Eric W. Biederman) - 2015-10-22 23:00 +0200
        Re: [PATCH] userns/capability: Add user namespace capability Andy Lutomirski <luto@amacapital.net> - 2015-10-22 23:10 +0200
          Re: [PATCH] userns/capability: Add user namespace capability ebiederm@xmission.com (Eric W. Biederman) - 2015-10-23 00:00 +0200
  Re: [PATCH] userns/capability: Add user namespace capability Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-10-19 16:30 +0200
    Re: [PATCH] userns/capability: Add user namespace capability Andy Lutomirski <luto@amacapital.net> - 2015-10-21 21:00 +0200
      Re: [PATCH] userns/capability: Add user namespace capability Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-10-21 21:20 +0200
        Re: [PATCH] userns/capability: Add user namespace capability Andy Lutomirski <luto@amacapital.net> - 2015-10-22 19:20 +0200

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