Re: [PATCH 00/18] prevent bounds-check bypass via speculative execution

Daniel Borkmann
2018-01-11T16:37:01Z

On 01/11/2018 04:58 PM, Dan Williams wrote:
> On Thu, Jan 11, 2018 at 1:54 AM, Jiri Kosina <jikos@kernel.org> wrote:
>> On Tue, 9 Jan 2018, Josh Poimboeuf wrote:
>>> On Tue, Jan 09, 2018 at 11:44:05AM -0800, Dan Williams wrote:
>>>> On Tue, Jan 9, 2018 at 11:34 AM, Jiri Kosina <jikos@kernel.org> wrote:
>>>>> On Fri, 5 Jan 2018, Dan Williams wrote:
>>>>>
>>>>> [ ... snip ... ]
>>>>>> Andi Kleen (1):
>>>>>> x86, barrier: stop speculation for failed access_ok
>>>>>>
>>>>>> Dan Williams (13):
>>>>>> x86: implement nospec_barrier()
>>>>>> [media] uvcvideo: prevent bounds-check bypass via speculative execution
>>>>>> carl9170: prevent bounds-check bypass via speculative execution
>>>>>> p54: prevent bounds-check bypass via speculative execution
>>>>>> qla2xxx: prevent bounds-check bypass via speculative execution
>>>>>> cw1200: prevent bounds-check bypass via speculative execution
>>>>>> Thermal/int340x: prevent bounds-check bypass via speculative execution
>>>>>> ipv6: prevent bounds-check bypass via speculative execution
>>>>>> ipv4: prevent bounds-check bypass via speculative execution
>>>>>> vfs, fdtable: prevent bounds-check bypass via speculative execution
>>>>>> net: mpls: prevent bounds-check bypass via speculative execution
>>>>>> udf: prevent bounds-check bypass via speculative execution
>>>>>> userns: prevent bounds-check bypass via speculative execution
>>>>>>
>>>>>> Mark Rutland (4):
>>>>>> asm-generic/barrier: add generic nospec helpers
>>>>>> Documentation: document nospec helpers
>>>>>> arm64: implement nospec_ptr()
>>>>>> arm: implement nospec_ptr()
>>>>>
>>>>> So considering the recent publication of [1], how come we all of a sudden
>>>>> don't need the barriers in ___bpf_prog_run(), namely for LD_IMM_DW and
>>>>> LDX_MEM_##SIZEOP, and something comparable for eBPF JIT?
>>>>>
>>>>> Is this going to be handled in eBPF in some other way?
>>>>>
>>>>> Without that in place, and considering Jann Horn's paper, it would seem
>>>>> like PTI doesn't really lock it down fully, right?
>>>>
>>>> Here is the latest (v3) bpf fix:
>>>>
>>>> https://patchwork.ozlabs.org/patch/856645/
>>>>
>>>> I currently have v2 on my 'nospec' branch and will move that to v3 for
>>>> the next update, unless it goes upstream before then.
>>
>> Daniel, I guess you're planning to send this still for 4.15?
>
> It's pending in the bpf.git tree:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=b2157399cc9

Sorry for the delay, just noticed the question now since not on Cc either:
It made it into in DaveM's tree already and part of his latest pull-req
to Linus.

>>> That patch seems specific to CONFIG_BPF_SYSCALL. Is the bpf() syscall
>>> the only attack vector? Or are there other ways to run bpf programs
>>> that we should be worried about?
>>
>> Seems like Alexei is probably the only person in the whole universe who
>> isn't CCed here ... let's fix that.
>
> He will be cc'd on v2 of this series which will be available later today.