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| author | Josef Bacik <jbacik@fb.com> | 2017-12-11 11:36:48 -0500 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2017-12-12 09:02:34 -0800 |
| commit | 9802d86585db91655c7d1929a4f6bbe0952ea88e (patch) | |
| tree | 53b334864518dd27b243eafc9ab510ac56ee3b74 /kernel/bpf/verifier.c | |
| parent | 8556e50994c8a8f5282fea008ae084d6d080648a (diff) | |
| download | lwn-9802d86585db91655c7d1929a4f6bbe0952ea88e.tar.gz lwn-9802d86585db91655c7d1929a4f6bbe0952ea88e.zip | |
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>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7afa92e9b409..e807bda7fe29 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4413,6 +4413,8 @@ 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 |