bpf: Allows per-cpu maps and map-in-map in sleepable programs

Since sleepable programs are now executing under migrate_disable
the per-cpu maps are safe to use.
The map-in-map were ok to use in sleepable from the time sleepable
progs were introduced.

Note that non-preallocated maps are still not safe, since there is
no rcu_read_lock yet in sleepable programs and dynamically allocated
map elements are relying on rcu protection. The sleepable programs
have rcu_read_lock_trace instead. That limitation will be addresses
in the future.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-9-alexei.starovoitov@gmail.com

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index c1ac7f964bc997925fd427f5192168829d812e5d..d63912e73ad9eda9c00dc8fd844384485a6256d0 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1148,7 +1148,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
                /* unknown flags */
                return -EINVAL;
 
-       WARN_ON_ONCE(!rcu_read_lock_held());
+       WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
 
        key_size = map->key_size;
 
@@ -1202,7 +1202,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
                /* unknown flags */
                return -EINVAL;
 
-       WARN_ON_ONCE(!rcu_read_lock_held());
+       WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held());
 
        key_size = map->key_size;
 

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 424c1ba0f52fc7350f2a648635ab3a0904798bea..15c15ea0abf54abc198a2aafaf791c4db98563fa 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10384,9 +10384,14 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,
                case BPF_MAP_TYPE_HASH:
                case BPF_MAP_TYPE_LRU_HASH:
                case BPF_MAP_TYPE_ARRAY:
+               case BPF_MAP_TYPE_PERCPU_HASH:
+               case BPF_MAP_TYPE_PERCPU_ARRAY:
+               case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+               case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+               case BPF_MAP_TYPE_HASH_OF_MAPS:
                        if (!is_preallocated_map(map)) {
                                verbose(env,
-                                       "Sleepable programs can only use preallocated hash maps\n");
+                                       "Sleepable programs can only use preallocated maps\n");
                                return -EINVAL;
                        }
                        break;