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bpf: allow sleepable uprobe programs to attach

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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: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Link: https://lore.kernel.org/r/fcd44a7cd204f372f6bb03ef794e829adeaef299.1655248076.git.delyank@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Delyan Kratunov 2022-06-14 23:10:43 +00:00 committed by Alexei Starovoitov
parent 8c7dcb84e3
commit 64ad7556c7
2 changed files with 12 additions and 8 deletions
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4
kernel/bpf/verifier.c
View File

@ -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;
}

16
kernel/events/core.c
View File

@ -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) {