Commit 64ad7556 authored by Delyan Kratunov's avatar Delyan Kratunov Committed by Alexei Starovoitov
Browse files

bpf: allow sleepable uprobe programs to attach 



uprobe and kprobe programs have the same program type, KPROBE, which is
currently not allowed to load sleepable programs.

To avoid adding a new UPROBE type, instead allow sleepable KPROBE
programs to load and defer the is-it-actually-a-uprobe-program check
to attachment time, where there's already validation of the
corresponding perf_event.

A corollary of this patch is that you can now load a sleepable kprobe
program but cannot attach it.

Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDelyan Kratunov <delyank@fb.com>
Link: https://lore.kernel.org/r/fcd44a7cd204f372f6bb03ef794e829adeaef299.1655248076.git.delyank@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 8c7dcb84

kernel/bpf/verifier.c

+2 −2
Original line number Diff line number Diff line
@@ -14829,8 +14829,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) 
	}



	if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&

	    prog->type != BPF_PROG_TYPE_LSM) {

		verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");

	    prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_KPROBE) {

		verbose(env, "Only fentry/fexit/fmod_ret, lsm, and kprobe/uprobe programs can be sleepable\n");

		return -EINVAL;

	}

kernel/events/core.c

+10 −6
Original line number Diff line number Diff line
@@ -10069,26 +10069,30 @@ static inline bool perf_event_is_tracing(struct perf_event *event) 
int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,

			    u64 bpf_cookie)

{

	bool is_kprobe, is_tracepoint, is_syscall_tp;

	bool is_kprobe, is_uprobe, is_tracepoint, is_syscall_tp;



	if (!perf_event_is_tracing(event))

		return perf_event_set_bpf_handler(event, prog, bpf_cookie);



	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;

	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_KPROBE;

	is_uprobe = event->tp_event->flags & TRACE_EVENT_FL_UPROBE;

	is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;

	is_syscall_tp = is_syscall_trace_event(event->tp_event);

	if (!is_kprobe && !is_tracepoint && !is_syscall_tp)

	if (!is_kprobe && !is_uprobe && !is_tracepoint && !is_syscall_tp)

		/* bpf programs can only be attached to u/kprobe or tracepoint */

		return -EINVAL;



	if ((is_kprobe && prog->type != BPF_PROG_TYPE_KPROBE) ||

	if (((is_kprobe || is_uprobe) && prog->type != BPF_PROG_TYPE_KPROBE) ||

	    (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) ||

	    (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))

		return -EINVAL;



	if (prog->type == BPF_PROG_TYPE_KPROBE && prog->aux->sleepable && !is_uprobe)

		/* only uprobe programs are allowed to be sleepable */

		return -EINVAL;



	/* Kprobe override only works for kprobes, not uprobes. */

	if (prog->kprobe_override &&

	    !(event->tp_event->flags & TRACE_EVENT_FL_KPROBE))

	if (prog->kprobe_override && !is_kprobe)

		return -EINVAL;



	if (is_tracepoint || is_syscall_tp) {