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

Dan Williams
2018-01-11T15:59:02Z

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

>> 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.