tcp: add RETPOLINE mitigation to sk_backlog_rcv

Use INDIRECT_CALL_INET() to avoid an indirect call
when/if CONFIG_RETPOLINE=y
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -1018,12 +1018,18 @@ static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *s
 
 int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb);
 
+INDIRECT_CALLABLE_DECLARE(int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb));
+INDIRECT_CALLABLE_DECLARE(int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb));
+
 static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 {
 	if (sk_memalloc_socks() && skb_pfmemalloc(skb))
 		return __sk_backlog_rcv(sk, skb);
 
-	return sk->sk_backlog_rcv(sk, skb);
+	return INDIRECT_CALL_INET(sk->sk_backlog_rcv,
+				  tcp_v6_do_rcv,
+				  tcp_v4_do_rcv,
+				  sk, skb);
 }
 
 static inline void sk_incoming_cpu_update(struct sock *sk)

net/core/sock.c

@@ -327,7 +327,10 @@ int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 	BUG_ON(!sock_flag(sk, SOCK_MEMALLOC));
 
 	noreclaim_flag = memalloc_noreclaim_save();
-	ret = sk->sk_backlog_rcv(sk, skb);
+	ret = INDIRECT_CALL_INET(sk->sk_backlog_rcv,
+				 tcp_v6_do_rcv,
+				 tcp_v4_do_rcv,
+				 sk, skb);
 	memalloc_noreclaim_restore(noreclaim_flag);
 
 	return ret;

net/ipv6/tcp_ipv6.c

@@ -72,7 +72,7 @@ static void	tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb);
 static void	tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 				      struct request_sock *req);
 
-static int	tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
+INDIRECT_CALLABLE_SCOPE int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
 
 static const struct inet_connection_sock_af_ops ipv6_mapped;
 const struct inet_connection_sock_af_ops ipv6_specific;
@@ -1466,7 +1466,8 @@ INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
  * This is because we cannot sleep with the original spinlock
  * held.
  */
-static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+INDIRECT_CALLABLE_SCOPE
+int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 {
 	struct ipv6_pinfo *np = tcp_inet6_sk(sk);
 	struct sk_buff *opt_skb = NULL;