fix: update selector_filter index assignment to use sel->index

This fixes an issue where PID filtering would not work correctly due to lost state updates. The selector filter now properly maintains its internal index state across multiple invocations.

Signed-off-by: arthur-zhang <[email protected]>

bpf/process/pfilter.h

@@ -342,15 +342,19 @@ selector_match(__u32 *f, struct selector_filter *sel,
 four:
 	res4 = process_filter(sel, f, enter, &msg->ns, &msg->caps);
 	index = next_pid_value(index, f, ty);
+	sel->index = index;
 three:
 	res3 = process_filter(sel, f, enter, &msg->ns, &msg->caps);
 	index = next_pid_value(index, f, ty);
+	sel->index = index;
 two:
 	res2 = process_filter(sel, f, enter, &msg->ns, &msg->caps);
 	index = next_pid_value(index, f, ty);
+	sel->index = index;
 one:
 	res1 = process_filter(sel, f, enter, &msg->ns, &msg->caps);
 	index = next_pid_value(index, f, ty);
+	sel->index = index;
 
 	if (ty == op_filter_notin)
 		return res1 & res2 & res3 & res4;