[PATCHv2 bpf-next 1/2] bpf: Reject multi kprobe programs in perf event attach

[Jiri Olsa <jolsa@kernel.org>]

PERF_EVENT_IOC_SET_BPF allows attaching multi and session kprobe or
uprobe programs through the standard perf event path. These programs
require attach-specific run context, which this path does not provide.
Attaching them can also let a uprobe reach a private-stack program
through a tail call.

Reject multi and session programs in __perf_event_set_bpf_prog().
Keep the existing sleepable-program check for standard kprobe and
uprobe programs.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/events/core.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 457d75ea7142..919f43cdb473 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11835,9 +11835,18 @@ static int __perf_event_set_bpf_prog(struct perf_event *event,
 	    (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))
 		return -EINVAL;
 
-	if (prog->type == BPF_PROG_TYPE_KPROBE && prog->sleepable && !is_uprobe)
+	if (prog->type == BPF_PROG_TYPE_KPROBE) {
 		/* only uprobe programs are allowed to be sleepable */
-		return -EINVAL;
+		if (prog->sleepable && !is_uprobe)
+			return -EINVAL;
+
+		/* only standard kprobe/uprobe programs are allowed to attach */
+		if (prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ||
+		    prog->expected_attach_type == BPF_TRACE_KPROBE_SESSION ||
+		    prog->expected_attach_type == BPF_TRACE_UPROBE_MULTI ||
+		    prog->expected_attach_type == BPF_TRACE_UPROBE_SESSION)
+			return -EINVAL;
+	}
 
 	if (prog->type == BPF_PROG_TYPE_TRACEPOINT && prog->sleepable) {
 		/*
-- 
2.43.0