linux-kernel - Re: [PATCH v2 0/3] seccomp: add PR_SECCOMP_EXT and SECCOMP_EXT_ACT

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Date:	Thu, 17 Apr 2014 11:31:46 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Kees Cook <keescook@...omium.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	John Johansen <john.johansen@...onical.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Will Drewry <wad@...omium.org>,
	Julien Tinnes <jln@...omium.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] seccomp: add PR_SECCOMP_EXT and SECCOMP_EXT_ACT_TSYNC

On Thu, Apr 17, 2014 at 11:18 AM, Kees Cook <keescook@...omium.org> wrote:
> On Thu, Apr 17, 2014 at 11:13 AM, Andy Lutomirski <luto@...capital.net> wrote:
>> On Thu, Apr 17, 2014 at 11:05 AM, Kees Cook <keescook@...omium.org> wrote:
>>> This adds the ability for threads to request seccomp filter
>>> synchronization across their thread group. To support this,
>>> seccomp locking on writes is introduced, along with refactoring
>>> of no_new_privs. Races with thread creation are handled via the
>>> tasklist_list.
>>>
>>> I think all the concerns raised during the discussion[1] of the first
>>> version of this patch have been addressed. However, the races involved
>>> have tricked me before. :)
>>>
>>
>> Would this be easier to use if there were a single syscall to set a
>> seccomp filter and sync threads?  That way you wouldn't have to write
>> your filter such that it gives permission to sync threads.
>
> That would be even cleaner, yes. I was hoping to see the new bpf jump
> tables before expanding into new filter calls, with the hope of doing
> it all at the same time. However, I guess we could just include a
> version number in the new call to indicate which filter type it was,
> and include flags (like "threadgroup sync") in there? I'm trying to
> imagine what would be the least painful for future-proofing.

What's the time frame on the new bpf stuff?  If it'll be ready for
3.16, it might not matter.

--Andy
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