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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAGXu5jLRokcbMEk=kK1_y7OiAAeSzHSve-VTTJ+fyWr9ypTQWQ@mail.gmail.com>
Date:	Thu, 17 Apr 2014 11:40:26 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Andy Lutomirski <luto@...capital.net>
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 11:31 AM, Andy Lutomirski <luto@...capital.net> wrote:
> 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.

I don't think seccomp will be extended to deal with that for a while,
since it'd require a lot of coordination first. So, for now, I think
adding a "flags" field should be sufficient. I'll work that up.

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/