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

[Jiri Kosina]

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@xxxxxxxxxx> 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?

> 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.

Thanks,

-- 
Jiri Kosina
SUSE Labs