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From: Djalal Harouni <tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Cc: Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
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	Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>,
	Arnaldo Carvalho de Melo
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	Mauro
Subject: Re: [PATCH v3 2/2] modules:capabilities: add a per-task modules autoload restriction
Date: Mon, 24 Apr 2017 20:35:06 +0200	[thread overview]
Message-ID: <CAEiveUevKr4FR49PnvKU2f3YzUF2SUvcxjq8Gpsj=Qf1ty+AGg@mail.gmail.com> (raw)
In-Reply-To: <CAGXu5jL_-cxidy_O4ORaN0iX9o7=hsi3DYTRvQs5w5363Z+MVg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Mon, Apr 24, 2017 at 8:02 PM, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
> On Mon, Apr 24, 2017 at 7:25 AM, Djalal Harouni <tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> On Sat, Apr 22, 2017 at 9:29 PM, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
>>> On Fri, Apr 21, 2017 at 11:51 PM, Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>>>> On Fri, Apr 21, 2017 at 5:12 PM, Djalal Harouni <tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>>>> On Sat, Apr 22, 2017 at 1:51 AM, Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>>>>>
>> [...]
>>>>> * DCCP use after free CVE-2017-6074
>>>>> * n_hldc CVE-2017-2636
>>>>> * XFRM framework CVE-2017-7184
>>>>> * L2TPv3 CVE-2016-10200
>>>>>
>>>>> Most of these need CAP_NET_ADMIN to be autoloaded, however we also
>>>>> need CAP_NET_ADMIN for other things... therefore it is better to have
>>>>> an extra facility that could coexist with CAP_NET_ADMIN and other
>>>>> sandbox features.
>>>>>
>>>>
>>>> I agree that the feature is important, but I think your implementation
>>>> is needlessly dangerous.  I imagine that the main uses that you care
>>>> about involve containers.  How about doing it in a safer way that
>>>> works for containers?  I can think of a few.  For example:
>>>>
>>>> 1. A sysctl that, if set, prevents autoloading outside the root
>>>> userns.  This isn't very flexible at all, but it might work.
>>>>
>>>> 2. Your patch, but require privilege within the calling namespace to
>>>> set the prctl.
>>>
>>> How about CAP_SYS_ADMIN || no_new_privs?
>>>
>>> -Kees
>>>
>>
>> Yes I can update as per Andy suggestion to require privileges inside
>> the calling namespace to set prctl. Other options that are not prctl
>> based have more variants, that make them hard to use.
>>
>> So I would got with CAP_SYS_ADMIN in the calling userns ||
>> no_new_privs , I would have said CAP_SYS_MODULE in the userns but it
>> seems better to standardize on CAP_SYS_ADMIN to set the prctl.
>
> Andy's concern is that it would provide an escalation from SYS_MODULE
> to SYS_ADMIN through some privileged process being tricked through a
> missing API provided by modules, so we have to use either SYS_ADMIN ||
> nnp.

Yes, I would say that programs expect that maybe such functionality is
not provided, but we don't know. I will update.

Thanks!


-- 
tixxdz

  parent reply	other threads:[~2017-04-24 18:35 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-19 22:20 [PATCH v3 0/2] modules:capabilities: automatic module loading restrictions Djalal Harouni
2017-04-19 22:20 ` [PATCH v3 1/2] modules:capabilities: automatic module loading restriction Djalal Harouni
2017-04-19 23:16   ` Andy Lutomirski
2017-04-20  2:22   ` Ben Hutchings
2017-04-20 12:44     ` [kernel-hardening] " Djalal Harouni
2017-04-20 15:02       ` Ben Hutchings
     [not found]         ` <1492700543.31767.23.camel-/+tVBieCtBitmTQ+vhA3Yw@public.gmane.org>
2017-04-20 20:39           ` [kernel-hardening] " Djalal Harouni
     [not found]             ` <CAEiveUdFL53XyQpacmN6f8F28M0bLQDcetpRXJjrJ10vDmQi8Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-20 21:28               ` Kees Cook
2017-04-19 22:20 ` [PATCH v3 2/2] modules:capabilities: add a per-task modules autoload restriction Djalal Harouni
2017-04-19 23:15   ` Andy Lutomirski
2017-04-19 23:43     ` Kees Cook
2017-04-20  2:41       ` Andy Lutomirski
     [not found]         ` <CALCETrUueOx1tqj+Ru93KGpy2HHR-A_GQ6DrAppiomkPTtX7Lw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-21 23:19           ` Kees Cook
2017-04-21 23:28             ` Andy Lutomirski
2017-04-21 23:40               ` Kees Cook
2017-04-21 23:51                 ` Andy Lutomirski
2017-04-22  0:12                   ` Djalal Harouni
     [not found]                     ` <CAEiveUcx8fwQgXdLPeMNsTjX2KPhQKH__a-XzcHko_1aCmh4sg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-22  1:19                       ` Djalal Harouni
2017-04-22  6:51                       ` Andy Lutomirski
     [not found]                         ` <CALCETrUT73CcPQx2T=1zWbOUhw9r-c_YqXw5-KTwxgWPgXuTwA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-22 19:29                           ` Kees Cook
     [not found]                             ` <CAGXu5jLV+WZyj+xnxVFkFEgEthNt6eXdcSgHT-=85mJ1ECZ1Rw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-24 14:25                               ` Djalal Harouni
2017-04-24 18:02                                 ` Kees Cook
     [not found]                                   ` <CAGXu5jL_-cxidy_O4ORaN0iX9o7=hsi3DYTRvQs5w5363Z+MVg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-24 18:35                                     ` Djalal Harouni [this message]
2017-04-21 23:52               ` Casey Schaufler
2017-04-22  0:00                 ` Andy Lutomirski
2017-04-22  0:13                   ` Casey Schaufler
2017-04-22  6:45                     ` Andy Lutomirski
2017-04-22 12:17               ` Djalal Harouni
     [not found]                 ` <CAEiveUdbQcfn1xC5xWMv91vL_uR1MGTvARqw-E4GDTMUZ6t=bA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-04 13:07                   ` Djalal Harouni
2017-05-04 14:58                     ` Serge E. Hallyn
2017-05-05 13:06                       ` Djalal Harouni
2017-05-05 16:18                     ` Andy Lutomirski
2017-04-20  1:57   ` kbuild test robot
     [not found]   ` <1492640420-27345-3-git-send-email-tixxdz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-04-19 22:38     ` Djalal Harouni
2017-04-24  4:29     ` Rusty Russell
2017-04-26  9:06       ` Djalal Harouni
2017-04-27  2:07         ` Rusty Russell
     [not found]           ` <87k266hacq.fsf-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>
2017-04-27 13:16             ` Djalal Harouni

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