Commit 7deca5ea authored by Dave Marchevsky's avatar Dave Marchevsky Committed by Alexei Starovoitov

bpf: Disable bpf_refcount_acquire kfunc calls until race conditions are fixed

As reported by Kumar in [0], the shared ownership implementation for BPF
programs has some race conditions which need to be addressed before it
can safely be used. This patch does so in a minimal way instead of
ripping out shared ownership entirely, as proper fixes for the issues
raised will follow ASAP, at which point this patch's commit can be
reverted to re-enable shared ownership.

The patch removes the ability to call bpf_refcount_acquire_impl from BPF
programs. Programs can only bump refcount and obtain a new owning
reference using this kfunc, so removing the ability to call it
effectively disables shared ownership.

Instead of changing success / failure expectations for
bpf_refcount-related selftests, this patch just disables them from
running for now.

  [0]: https://lore.kernel.org/bpf/d7hyspcow5wtjcmw4fugdgyp3fwhljwuscp3xyut5qnwivyeru@ysdq543otzv2/Reported-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarDave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230424204321.2680232-1-davemarchevsky@fb.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 35150203
......@@ -10509,7 +10509,10 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i);
return -EINVAL;
}
if (rec->refcount_off >= 0) {
verbose(env, "bpf_refcount_acquire calls are disabled for now\n");
return -EINVAL;
}
meta->arg_refcount_acquire.btf = reg->btf;
meta->arg_refcount_acquire.btf_id = reg->btf_id;
break;
......
......@@ -9,10 +9,8 @@
void test_refcounted_kptr(void)
{
RUN_TESTS(refcounted_kptr);
}
void test_refcounted_kptr_fail(void)
{
RUN_TESTS(refcounted_kptr_fail);
}
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment