ipv6: Early TCP socket demux

This is the IPv6 missing bits for infrastructure added in commit
41063e9dd1195 (ipv4: Early TCP socket demux.)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 59 insertions, 8 deletions

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 00cbb4384c79..9e34c877a770 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -96,14 +96,15 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
                                               const __be16 sport,
                                               const __be16 dport)
 {
-        struct sock *sk;
+        struct sock *sk = skb_steal_sock(skb);
 
-        if (unlikely(sk = skb_steal_sock(skb)))
+        if (sk)
                 return sk;
-        else return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
-                                   &ipv6_hdr(skb)->saddr, sport,
-                                   &ipv6_hdr(skb)->daddr, ntohs(dport),
-                                   inet6_iif(skb));
+
+        return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo,
+                              &ipv6_hdr(skb)->saddr, sport,
+                              &ipv6_hdr(skb)->daddr, ntohs(dport),
+                              inet6_iif(skb));
 }
 
 extern struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
diff --git a/include/net/protocol.h b/include/net/protocol.h
index 057f2d315567..929528c73fe8 100644
--- a/include/net/protocol.h
+++ b/include/net/protocol.h
@@ -52,6 +52,8 @@ struct net_protocol {
 
 #if IS_ENABLED(CONFIG_IPV6)
 struct inet6_protocol {
+        void    (*early_demux)(struct sk_buff *skb);
+
         int     (*handler)(struct sk_buff *skb);
 
         void    (*err_handler)(struct sk_buff *skb,
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index bda8cac2ae91..981ff1eef28c 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -314,6 +314,7 @@ drop:
 }
 
 int sysctl_ip_early_demux __read_mostly = 1;
+EXPORT_SYMBOL(sysctl_ip_early_demux);
 
 static int ip_rcv_finish(struct sk_buff *skb)
 {
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 5ab923e51af3..47975e363fcd 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -47,9 +47,18 @@
 
 
 
-inline int ip6_rcv_finish( struct sk_buff *skb)
+int ip6_rcv_finish(struct sk_buff *skb)
 {
-        if (skb_dst(skb) == NULL)
+        if (sysctl_ip_early_demux && !skb_dst(skb)) {
+                const struct inet6_protocol *ipprot;
+
+                rcu_read_lock();
+                ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
+                if (ipprot && ipprot->early_demux)
+                        ipprot->early_demux(skb);
+                rcu_read_unlock();
+        }
+        if (!skb_dst(skb))
                 ip6_route_input(skb);
 
         return dst_input(skb);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f49476e2d884..221224e72507 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1674,6 +1674,43 @@ do_time_wait:
         goto discard_it;
 }
 
+static void tcp_v6_early_demux(struct sk_buff *skb)
+{
+        const struct ipv6hdr *hdr;
+        const struct tcphdr *th;
+        struct sock *sk;
+
+        if (skb->pkt_type != PACKET_HOST)
+                return;
+
+        if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
+                return;
+
+        hdr = ipv6_hdr(skb);
+        th = tcp_hdr(skb);
+
+        if (th->doff < sizeof(struct tcphdr) / 4)
+                return;
+
+        sk = __inet6_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
+                                        &hdr->saddr, th->source,
+                                        &hdr->daddr, ntohs(th->dest),
+                                        inet6_iif(skb));
+        if (sk) {
+                skb->sk = sk;
+                skb->destructor = sock_edemux;
+                if (sk->sk_state != TCP_TIME_WAIT) {
+                        struct dst_entry *dst = sk->sk_rx_dst;
+                        struct inet_sock *icsk = inet_sk(sk);
+                        if (dst)
+                                dst = dst_check(dst, 0);
+                        if (dst &&
+                            icsk->rx_dst_ifindex == inet6_iif(skb))
+                                skb_dst_set_noref(skb, dst);
+                }
+        }
+}
+
 static struct timewait_sock_ops tcp6_timewait_sock_ops = {
         .twsk_obj_size  = sizeof(struct tcp6_timewait_sock),
         .twsk_unique    = tcp_twsk_unique,
@@ -1984,6 +2021,7 @@ struct proto tcpv6_prot = {
 };
 
 static const struct inet6_protocol tcpv6_protocol = {
+        .early_demux    =       tcp_v6_early_demux,
         .handler        =       tcp_v6_rcv,
         .err_handler    =       tcp_v6_err,
         .gso_send_check =       tcp_v6_gso_send_check,