Re: [PATCH 1/2] bpf: add a bpf_override_function helper

From: Ingo Molnar
Date: Fri Nov 10 2017 - 04:35:20 EST



* Josef Bacik <josef@xxxxxxxxxxxxxx> wrote:

> @@ -551,6 +578,10 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
> return &bpf_get_stackid_proto;
> case BPF_FUNC_perf_event_read_value:
> return &bpf_perf_event_read_value_proto;
> + case BPF_FUNC_override_return:
> + pr_warn_ratelimited("%s[%d] is installing a program with bpf_override_return helper that may cause unexpected behavior!",
> + current->comm, task_pid_nr(current));
> + return &bpf_override_return_proto;

So if this new functionality is used we'll always print this into the syslog?

The warning is also a bit passive aggressive about informing the user: what
unexpected behavior can happen, what is the worst case?

Thanks,

Ingo