From: Daniel Borkmann Date: Mon, 13 May 2019 23:18:55 +0000 (+0200) Subject: bpf: add map_lookup_elem_sys_only for lookups from syscall side X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=effc63a8147d3da04c39508d6c635f8d2062e2b9;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git bpf: add map_lookup_elem_sys_only for lookups from syscall side commit c6110222c6f49ea68169f353565eb865488a8619 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f22171d4ca85..2f6ff6e53290 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -28,6 +28,7 @@ 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 176170b002a3..e791adc6cdb7 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -579,7 +579,10 @@ static int map_lookup_elem(union bpf_attr *attr) err = bpf_fd_htab_map_lookup_elem(map, key, 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 (ptr) memcpy(value, ptr, value_size); rcu_read_unlock();