From c6110222c6f49ea68169f353565eb865488a8619 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 14 May 2019 01:18:55 +0200 Subject: [PATCH] bpf: add map_lookup_elem_sys_only for lookups from syscall side Add a callback map_lookup_elem_sys_only() that map implementations could use over map_lookup_elem() from system call side in case the map implementation needs to handle the latter differently than from the BPF data path. If map_lookup_elem_sys_only() is set, this will be preferred pick for map lookups out of user space. This hook is used in a follow-up fix for LRU map, but once development window opens, we can convert other map types from map_lookup_elem() (here, the one called upon BPF_MAP_LOOKUP_ELEM cmd is meant) over to use the callback to simplify and clean up the latter. Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 1 + kernel/bpf/syscall.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 59631dd0777c..4fb3aa2dc975 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -36,6 +36,7 @@ struct bpf_map_ops { void (*map_free)(struct bpf_map *map); int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key); void (*map_release_uref)(struct bpf_map *map); + void *(*map_lookup_elem_sys_only)(struct bpf_map *map, void *key); /* funcs callable from userspace and from eBPF programs */ void *(*map_lookup_elem)(struct bpf_map *map, void *key); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ad3ccf82f31d..cb5440b02e82 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -808,7 +808,10 @@ static int map_lookup_elem(union bpf_attr *attr) err = map->ops->map_peek_elem(map, value); } else { rcu_read_lock(); - ptr = map->ops->map_lookup_elem(map, key); + if (map->ops->map_lookup_elem_sys_only) + ptr = map->ops->map_lookup_elem_sys_only(map, key); + else + ptr = map->ops->map_lookup_elem(map, key); if (IS_ERR(ptr)) { err = PTR_ERR(ptr); } else if (!ptr) { -- 2.30.2