Commit b93ef089 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpf: Fix the irq and nmi check in bpf_sk_storage for tracing usage 



The intention of the current check is to avoid using bpf_sk_storage
in irq and nmi.  Jakub pointed out that the current check cannot
do that.  For example, in_serving_softirq() returns true
if the softirq handling is interrupted by hard irq.

Fixes: 8e4597c6 ("bpf: Allow using bpf_sk_storage in FENTRY/FEXIT/RAW_TP")
Suggested-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201116200113.2868539-1-kafai@fb.com
parent 024cd2cb

net/core/bpf_sk_storage.c

+2 −2
Original line number Diff line number Diff line
@@ -415,7 +415,7 @@ static bool bpf_sk_storage_tracing_allowed(const struct bpf_prog *prog) 
BPF_CALL_4(bpf_sk_storage_get_tracing, struct bpf_map *, map, struct sock *, sk,

	   void *, value, u64, flags)

{

	if (!in_serving_softirq() && !in_task())

	if (in_irq() || in_nmi())

		return (unsigned long)NULL;



	return (unsigned long)____bpf_sk_storage_get(map, sk, value, flags);
@@ -424,7 +424,7 @@ BPF_CALL_4(bpf_sk_storage_get_tracing, struct bpf_map *, map, struct sock *, sk, 
BPF_CALL_2(bpf_sk_storage_delete_tracing, struct bpf_map *, map,

	   struct sock *, sk)

{

	if (!in_serving_softirq() && !in_task())

	if (in_irq() || in_nmi())

		return -EPERM;



	return ____bpf_sk_storage_delete(map, sk);