Commit ba90c2cc authored by KP Singh's avatar KP Singh Committed by Andrii Nakryiko
Browse files

bpf: Allow usage of BPF ringbuffer in sleepable programs 



The BPF ringbuffer map is pre-allocated and the implementation logic
does not rely on disabling preemption or per-cpu data structures. Using
the BPF ringbuffer sleepable LSM and tracing programs does not trigger
any warnings with DEBUG_ATOMIC_SLEEP, DEBUG_PREEMPT,
PROVE_RCU and PROVE_LOCKING and LOCKDEP enabled.

This allows helpers like bpf_copy_from_user and bpf_ima_inode_hash to
write to the BPF ring buffer from sleepable BPF programs.

Signed-off-by: default avatarKP Singh <kpsingh@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210204193622.3367275-2-kpsingh@kernel.org
parent ec45c5fa

kernel/bpf/verifier.c

+3 −1
Original line number Diff line number Diff line
@@ -10024,9 +10024,11 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, 
				return -EINVAL;

			}

			break;

		case BPF_MAP_TYPE_RINGBUF:

			break;

		default:

			verbose(env,

				"Sleepable programs can only use array and hash maps\n");

				"Sleepable programs can only use array, hash, and ringbuf maps\n");

			return -EINVAL;

		}