Commit db8eae6b authored by Jiri Olsa's avatar Jiri Olsa Committed by Daniel Borkmann
Browse files

bpf: Force kprobe multi expected_attach_type for kprobe_multi link 



We currently allow to create perf link for program with
expected_attach_type == BPF_TRACE_KPROBE_MULTI.

This will cause crash when we call helpers like get_attach_cookie or
get_func_ip in such program, because it will call the kprobe_multi's
version (current->bpf_ctx context setup) of those helpers while it
expects perf_link's current->bpf_ctx context setup.

Making sure that we use BPF_TRACE_KPROBE_MULTI expected_attach_type
only for programs attaching through kprobe_multi link.

Fixes: ca74823c ("bpf: Add cookie support to programs attached with kprobe multi link")
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230618131414.75649-1-jolsa@kernel.org
parent 9724160b

kernel/bpf/syscall.c

+5 −0
Original line number Diff line number Diff line
@@ -3440,6 +3440,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, 
		return prog->enforce_expected_attach_type &&

			prog->expected_attach_type != attach_type ?

			-EINVAL : 0;

	case BPF_PROG_TYPE_KPROBE:

		if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI &&

		    attach_type != BPF_TRACE_KPROBE_MULTI)

			return -EINVAL;

		return 0;

	default:

		return 0;

	}