diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2018-05-15 09:27:05 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-08 13:05:10 +0100 |
| commit | def8c1d045a0fb457a1136f7edcc5ed8b2d81af6 (patch) | |
| tree | e20d00cb4410ab895fb09bee70d3beeb411388f3 /include | |
| parent | 62e0865f2015af8bdc56da33243f66091b0a918d (diff) | |
bpf: Prevent memory disambiguation attack
commit af86ca4e3088fe5eacf2f7e58c01fa68ca067672 upstream.
Detect code patterns where malicious 'speculative store bypass' can be used
and sanitize such patterns.
39: (bf) r3 = r10
40: (07) r3 += -216
41: (79) r8 = *(u64 *)(r7 +0) // slow read
42: (7a) *(u64 *)(r10 -72) = 0 // verifier inserts this instruction
43: (7b) *(u64 *)(r8 +0) = r3 // this store becomes slow due to r8
44: (79) r1 = *(u64 *)(r6 +0) // cpu speculatively executes this load
45: (71) r2 = *(u8 *)(r1 +0) // speculatively arbitrary 'load byte'
// is now sanitized
Above code after x86 JIT becomes:
e5: mov %rbp,%rdx
e8: add $0xffffffffffffff28,%rdx
ef: mov 0x0(%r13),%r14
f3: movq $0x0,-0x48(%rbp)
fb: mov %rdx,0x0(%r14)
ff: mov 0x0(%rbx),%rdi
103: movzbq 0x0(%rdi),%rsi
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 4.9:
- Add bpf_verifier_env parameter to check_stack_write()
- Look up stack slot_types with state->stack_slot_type[] rather than
state->stack[].slot_type[]
- Drop bpf_verifier_env argument to verbose()
- Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bpf_verifier.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 070fc49e39e2..5031defe59c5 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -71,6 +71,7 @@ struct bpf_insn_aux_data { enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */ }; + int sanitize_stack_off; /* stack slot to be cleared */ bool seen; /* this insn was processed by the verifier */ }; |