linux-kernel - [PATCH bpf-next 3/6] bpf: sockmap: call sock_map_update

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Message-Id: <20200819092436.58232-4-lmb@cloudflare.com>
Date:   Wed, 19 Aug 2020 10:24:33 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     jakub@...udflare.com, john.fastabend@...il.com,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenz Bauer <lmb@...udflare.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     kernel-team@...udflare.com, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next 3/6] bpf: sockmap: call sock_map_update_elem directly

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@...udflare.com>
---
 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