diff options
| author |   Alexei Starovoitov <ast@fb.com> | 2017-12-14 17:55:14 -0800 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2017-12-17 20:34:36 +0100 |
| commit | 60b58afc96c9df71871df2dbad42037757ceef26 (patch) | |
| tree | 5651c4845120fc28c9712f53f31962adfd4abe73 /kernel | |
| parent | bpf: add support for bpf_call to interpreter (diff) | |
| download | linux-dev-60b58afc96c9df71871df2dbad42037757ceef26.tar.xz linux-dev-60b58afc96c9df71871df2dbad42037757ceef26.zip | |
bpf: fix net.core.bpf_jit_enable race
global bpf_jit_enable variable is tested multiple times in JITs,
blinding and verifier core. The malicious root can try to toggle
it while loading the programs. This race condition was accounted
for and there should be no issues, but it's safer to avoid
this race condition.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/core.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
2 files changed, 3 insertions, 2 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index dc12c4fd006e..bda911644b1c 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -94,6 +94,7 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) fp->pages = size / PAGE_SIZE; fp->aux = aux; fp->aux->prog = fp; + fp->jit_requested = ebpf_jit_enabled(); INIT_LIST_HEAD_RCU(&fp->aux->ksym_lnode); @@ -721,7 +722,7 @@ struct bpf_prog *bpf_jit_blind_constants(struct bpf_prog *prog) struct bpf_insn *insn; int i, rewritten; - if (!bpf_jit_blinding_enabled()) + if (!bpf_jit_blinding_enabled(prog)) return prog; clone = bpf_prog_clone_create(prog, GFP_USER); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index cdc1f043c69b..8e0e4cd0d5e4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5080,7 +5080,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup * handlers are currently limited to 64 bit only. */ - if (ebpf_jit_enabled() && BITS_PER_LONG == 64 && + if (prog->jit_requested && BITS_PER_LONG == 64 && insn->imm == BPF_FUNC_map_lookup_elem) { map_ptr = env->insn_aux_data[i + delta].map_ptr; if (map_ptr == BPF_MAP_PTR_POISON || |