bpf: sockmap: Add UDP support

Allow adding hashed UDP sockets to sockmaps.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200309111243.6982-9-lmb@cloudflare.com

net/core/sock_map.c

@@ -11,6 +11,7 @@
 #include <linux/list.h>
 #include <linux/jhash.h>
 #include <linux/sock_diag.h>
+#include <net/udp.h>
 
 struct bpf_stab {
 	struct bpf_map map;
@@ -147,7 +148,19 @@ static int sock_map_init_proto(struct sock *sk, struct sk_psock *psock)
 
 	sock_owned_by_me(sk);
 
-	prot = tcp_bpf_get_proto(sk, psock);
+	switch (sk->sk_type) {
+	case SOCK_STREAM:
+		prot = tcp_bpf_get_proto(sk, psock);
+		break;
+
+	case SOCK_DGRAM:
+		prot = udp_bpf_get_proto(sk, psock);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
 	if (IS_ERR(prot))
 		return PTR_ERR(prot);
 
@@ -162,7 +175,7 @@ static struct sk_psock *sock_map_psock_get_checked(struct sock *sk)
 	rcu_read_lock();
 	psock = sk_psock(sk);
 	if (psock) {
-		if (sk->sk_prot->recvmsg != tcp_bpf_recvmsg) {
+		if (sk->sk_prot->close != sock_map_close) {
 			psock = ERR_PTR(-EBUSY);
 			goto out;
 		}
@@ -474,15 +487,31 @@ static bool sock_map_op_okay(const struct bpf_sock_ops_kern *ops)
 	       ops->op == BPF_SOCK_OPS_TCP_LISTEN_CB;
 }
 
-static bool sock_map_sk_is_suitable(const struct sock *sk)
+static bool sk_is_tcp(const struct sock *sk)
 {
 	return sk->sk_type == SOCK_STREAM &&
 	       sk->sk_protocol == IPPROTO_TCP;
 }
 
+static bool sk_is_udp(const struct sock *sk)
+{
+	return sk->sk_type == SOCK_DGRAM &&
+	       sk->sk_protocol == IPPROTO_UDP;
+}
+
+static bool sock_map_sk_is_suitable(const struct sock *sk)
+{
+	return sk_is_tcp(sk) || sk_is_udp(sk);
+}
+
 static bool sock_map_sk_state_allowed(const struct sock *sk)
 {
-	return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_LISTEN);
+	if (sk_is_tcp(sk))
+		return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_LISTEN);
+	else if (sk_is_udp(sk))
+		return sk_hashed(sk);
+
+	return false;
 }
 
 static int sock_map_update_elem(struct bpf_map *map, void *key,