diff options
| author | Josef Bacik <jbacik@fb.com> | 2017-11-07 15:28:42 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-11-11 12:18:05 +0900 |
| commit | dd0bb688eaa241b5655d396d45366cba9225aed9 (patch) | |
| tree | 80e320112959e90d474fd20e644b8377217dad0b /kernel/bpf | |
| parent | 54985120a1c461b74f9510e5d730971f2a2383b1 (diff) | |
bpf: add a bpf_override_function helper
Error injection is sloppy and very ad-hoc. BPF could fill this niche
perfectly with it's kprobe functionality. We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations. Accomplish this with the bpf_override_funciton
helper. This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function. This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/core.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
2 files changed, 5 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 8a6c37762330..271daad31f37 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1326,6 +1326,9 @@ EVAL4(PROG_NAME_LIST, 416, 448, 480, 512) bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp) { + if (fp->kprobe_override) + return false; + if (!array->owner_prog_type) { /* There's no owner yet where we could check for * compatibility. diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4a942e2e753d..bc464b8ec91e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4357,6 +4357,8 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) prog->dst_needed = 1; if (insn->imm == BPF_FUNC_get_prandom_u32) bpf_user_rnd_init_once(); + if (insn->imm == BPF_FUNC_override_return) + prog->kprobe_override = 1; if (insn->imm == BPF_FUNC_tail_call) { /* If we tail call into other programs, we * cannot make any assumptions since they can |