[MODERATED] [PATCH 0/5] SSB extra v2 0

[Dave Hansen <dave.hansen@intel.com>]

This is still highly RFC.  I would mostly like feedback from folks
as to whether the overall method of plugging into BPF is more
acceptable now.  This has not been tested on real hardware yet.

--

BPF is a potential source of gadgets that can be used for memory
diambiguation-based attacks.  To help mitigate these, we enable
the bit in SPEC_CTRL which enables the reduced (memory)
speculation mode on the processor when runing BPF code.

This improves on the last version quite a bit: there is no overhead
for unmitigated BPF programs.  Instead of calling the mitigation
code unconditionally, we stick it in a wrapper function which then
calls the real BPF payload.  In the unmitigated case, the function
pointer just points to the payload directly.

This also does not do any of the arch-specific bits.  Thomas has
some code to do that.

Big caveat: I've only been looking at BPF for a couple of days.
I'm not deepy familiar with the code and I'm positive there are bugs
and tons of ways to optimize this.

Thomas Gleixner(1):
  bpf: Add speculation control interface

Dave Hansen (4):
  bpf: install mitigation wrapper for untrusted programs
  bpf: set prog->need_mitigation when calling other programs
  bpf: populate prog->need_mitigation for unprivileged programs
  bpf: only mitigate programs that write to memory

 include/linux/bpf_verifier.h |  1 +
 include/linux/filter.h       |  7 ++++++-
 include/linux/nospec.h       |  4 ++++
 kernel/bpf/core.c            | 14 ++++++++++++++
 kernel/bpf/verifier.c        | 13 +++++++++++++
 net/core/filter.c            | 25 +++++++++++++++++++++++++
 6 files changed, 63 insertions(+), 1 deletion(-)

-- 
2.9.5