soreuseport: TCP/IPv6 implementation

Motivation for soreuseport would be something like a web server
binding to port 80 running with multiple threads, where each thread
might have it's own listener socket.  This could be done as an
alternative to other models: 1) have one listener thread which
dispatches completed connections to workers. 2) accept on a single
listener socket from multiple threads.  In case #1 the listener thread
can easily become the bottleneck with high connection turn-over rate.
In case #2, the proportion of connections accepted per thread tends
to be uneven under high connection load (assuming simple event loop:
while (1) { accept(); process() }, wakeup does not promote fairness
among the sockets.  We have seen the  disproportion to be as high
as 3:1 ratio between thread accepting most connections and the one
accepting the fewest.  With so_reusport the distribution is
uniform.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 9e34c87..7ca75cb 100644 (file)
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -71,6 +71,8 @@ extern struct sock *__inet6_lookup_established(struct net *net,
 
 extern struct sock *inet6_lookup_listener(struct net *net,
                                          struct inet_hashinfo *hashinfo,
+                                         const struct in6_addr *saddr,
+                                         const __be16 sport,
                                          const struct in6_addr *daddr,
                                          const unsigned short hnum,
                                          const int dif);
@@ -88,7 +90,8 @@ static inline struct sock *__inet6_lookup(struct net *net,
        if (sk)
                return sk;
 
-       return inet6_lookup_listener(net, hashinfo, daddr, hnum, dif);
+       return inet6_lookup_listener(net, hashinfo, saddr, sport,
+                                    daddr, hnum, dif);
 }
 
 static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,

diff --git a/include/net/netfilter/nf_tproxy_core.h b/include/net/netfilter/nf_tproxy_core.h
index 1937964..36d9379 100644 (file)
--- a/include/net/netfilter/nf_tproxy_core.h
+++ b/include/net/netfilter/nf_tproxy_core.h
@@ -152,6 +152,7 @@ nf_tproxy_get_sock_v6(struct net *net, const u8 protocol,
                        break;
                case NFT_LOOKUP_LISTENER:
                        sk = inet6_lookup_listener(net, &tcp_hashinfo,
+                                                  saddr, sport,
                                                   daddr, ntohs(dport),
                                                   in->ifindex);
 

diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 3064785..e4297a3 100644 (file)
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -32,6 +32,9 @@ int inet6_csk_bind_conflict(const struct sock *sk,
 {
        const struct sock *sk2;
        const struct hlist_node *node;
+       int reuse = sk->sk_reuse;
+       int reuseport = sk->sk_reuseport;
+       int uid = sock_i_uid((struct sock *)sk);
 
        /* We must walk the whole port owner list in this case. -DaveM */
        /*
@@ -42,11 +45,17 @@ int inet6_csk_bind_conflict(const struct sock *sk,
                if (sk != sk2 &&
                    (!sk->sk_bound_dev_if ||
                     !sk2->sk_bound_dev_if ||
-                    sk->sk_bound_dev_if == sk2->sk_bound_dev_if) &&
-                   (!sk->sk_reuse || !sk2->sk_reuse ||
-                    sk2->sk_state == TCP_LISTEN) &&
-                    ipv6_rcv_saddr_equal(sk, sk2))
-                       break;
+                    sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
+                       if ((!reuse || !sk2->sk_reuse ||
+                            sk2->sk_state == TCP_LISTEN) &&
+                           (!reuseport || !sk2->sk_reuseport ||
+                            (sk2->sk_state != TCP_TIME_WAIT &&
+                             !uid_eq(uid,
+                                     sock_i_uid((struct sock *)sk2))))) {
+                               if (ipv6_rcv_saddr_equal(sk, sk2))
+                                       break;
+                       }
+               }
        }
 
        return node != NULL;

diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index dea17fd..32b4a16 100644 (file)
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -158,25 +158,38 @@ static inline int compute_score(struct sock *sk, struct net *net,
 }
 
 struct sock *inet6_lookup_listener(struct net *net,
-               struct inet_hashinfo *hashinfo, const struct in6_addr *daddr,
+               struct inet_hashinfo *hashinfo, const struct in6_addr *saddr,
+               const __be16 sport, const struct in6_addr *daddr,
                const unsigned short hnum, const int dif)
 {
        struct sock *sk;
        const struct hlist_nulls_node *node;
        struct sock *result;
-       int score, hiscore;
+       int score, hiscore, matches = 0, reuseport = 0;
+       u32 phash = 0;
        unsigned int hash = inet_lhashfn(net, hnum);
        struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
 
        rcu_read_lock();
 begin:
        result = NULL;
-       hiscore = -1;
+       hiscore = 0;
        sk_nulls_for_each(sk, node, &ilb->head) {
                score = compute_score(sk, net, hnum, daddr, dif);
                if (score > hiscore) {
                        hiscore = score;
                        result = sk;
+                       reuseport = sk->sk_reuseport;
+                       if (reuseport) {
+                               phash = inet6_ehashfn(net, daddr, hnum,
+                                                     saddr, sport);
+                               matches = 1;
+                       }
+               } else if (score == hiscore && reuseport) {
+                       matches++;
+                       if (((u64)phash * matches) >> 32 == 0)
+                               result = sk;
+                       phash = next_pseudo_random32(phash);
                }
        }
        /*

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3701c3c..06087e5 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -834,7 +834,8 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
                 * no RST generated if md5 hash doesn't match.
                 */
                sk1 = inet6_lookup_listener(dev_net(skb_dst(skb)->dev),
-                                          &tcp_hashinfo, &ipv6h->daddr,
+                                          &tcp_hashinfo, &ipv6h->saddr,
+                                          th->source, &ipv6h->daddr,
                                           ntohs(th->source), inet6_iif(skb));
                if (!sk1)
                        return;
@@ -1598,6 +1599,7 @@ do_time_wait:
                struct sock *sk2;
 
                sk2 = inet6_lookup_listener(dev_net(skb->dev), &tcp_hashinfo,
+                                           &ipv6_hdr(skb)->saddr, th->source,
                                            &ipv6_hdr(skb)->daddr,
                                            ntohs(th->dest), inet6_iif(skb));
                if (sk2 != NULL) {