[PATCH bpf-next 3/6] bpf: sockmap: call sock_map_update_elem directly

From: Lorenz Bauer
Date: Wed Aug 19 2020 - 05:38:13 EST


Don't go via map->ops to call sock_map_update_elem, since we know
what function to call in bpf_map_update_value. Since
check_map_func_compatibility doesn't allow calling
BPF_FUNC_map_update_elem from BPF context, we can remove
ops->map_update_elem and rename the function to
sock_map_update_elem_sys.

Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
---
include/linux/bpf.h | 7 +++++++
kernel/bpf/syscall.c | 5 +++--
net/core/sock_map.c | 6 ++----
3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cef4ef0d2b4e..cf3416d1b8c2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1635,6 +1635,7 @@ int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
struct bpf_prog *old, u32 which);
int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog);
int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype);
+int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value, u64 flags);
void sock_map_unhash(struct sock *sk);
void sock_map_close(struct sock *sk, long timeout);
#else
@@ -1656,6 +1657,12 @@ static inline int sock_map_prog_detach(const union bpf_attr *attr,
{
return -EOPNOTSUPP;
}
+
+static inline int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value,
+ u64 flags)
+{
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_BPF_STREAM_PARSER */

#if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2f343ce15747..5867cf615a3c 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -157,10 +157,11 @@ static int bpf_map_update_value(struct bpf_map *map, struct fd f, void *key,
if (bpf_map_is_dev_bound(map)) {
return bpf_map_offload_update_elem(map, key, value, flags);
} else if (map->map_type == BPF_MAP_TYPE_CPUMAP ||
- map->map_type == BPF_MAP_TYPE_SOCKHASH ||
- map->map_type == BPF_MAP_TYPE_SOCKMAP ||
map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
return map->ops->map_update_elem(map, key, value, flags);
+ } else if (map->map_type == BPF_MAP_TYPE_SOCKHASH ||
+ map->map_type == BPF_MAP_TYPE_SOCKMAP) {
+ return sock_map_update_elem_sys(map, key, value, flags);
} else if (IS_FD_PROG_ARRAY(map)) {
return bpf_fd_array_map_update_elem(map, f.file, key, value,
flags);
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index f464a0ebc871..018367fb889f 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -562,8 +562,8 @@ static bool sock_map_sk_state_allowed(const struct sock *sk)
static int sock_hash_update_common(struct bpf_map *map, void *key,
struct sock *sk, u64 flags);

-int sock_map_update_elem(struct bpf_map *map, void *key,
- void *value, u64 flags)
+int sock_map_update_elem_sys(struct bpf_map *map, void *key,
+ void *value, u64 flags)
{
struct socket *sock;
struct sock *sk;
@@ -687,7 +687,6 @@ const struct bpf_map_ops sock_map_ops = {
.map_free = sock_map_free,
.map_get_next_key = sock_map_get_next_key,
.map_lookup_elem_sys_only = sock_map_lookup_sys,
- .map_update_elem = sock_map_update_elem,
.map_delete_elem = sock_map_delete_elem,
.map_lookup_elem = sock_map_lookup,
.map_release_uref = sock_map_release_progs,
@@ -1181,7 +1180,6 @@ const struct bpf_map_ops sock_hash_ops = {
.map_alloc = sock_hash_alloc,
.map_free = sock_hash_free,
.map_get_next_key = sock_hash_get_next_key,
- .map_update_elem = sock_map_update_elem,
.map_delete_elem = sock_hash_delete_elem,
.map_lookup_elem = sock_hash_lookup,
.map_lookup_elem_sys_only = sock_hash_lookup_sys,
--
2.25.1