timewait_sock: Create and use getpeer op.

The only thing AF-specific about remembering the timestamp
for a time-wait TCP socket is getting the peer.

Abstract that behind a new timewait_sock_ops vector.

Support for real IPV6 sockets is not filled in yet, but
curiously this makes timewait recycling start to work
for v4-mapped ipv6 sockets.

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 63 insertions, 37 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3e239641d4ee..4097320caa25 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -313,6 +313,7 @@ extern void tcp_shutdown (struct sock *sk, int how);
 extern int tcp_v4_rcv(struct sk_buff *skb);
 
 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
+extern void *tcp_v4_tw_get_peer(struct sock *sk);
 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                        size_t size);
diff --git a/include/net/timewait_sock.h b/include/net/timewait_sock.h
index 97c3b14da55d..053b3cf2c66a 100644
--- a/include/net/timewait_sock.h
+++ b/include/net/timewait_sock.h
@@ -21,6 +21,7 @@ struct timewait_sock_ops {
         int             (*twsk_unique)(struct sock *sk,
                                        struct sock *sktw, void *twp);
         void            (*twsk_destructor)(struct sock *sk);
+        void            *(*twsk_getpeer)(struct sock *sk);
 };
 
 static inline int twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
@@ -39,4 +40,11 @@ static inline void twsk_destructor(struct sock *sk)
                 sk->sk_prot->twsk_prot->twsk_destructor(sk);
 }
 
+static inline void *twsk_getpeer(struct sock *sk)
+{
+        if (sk->sk_prot->twsk_prot->twsk_getpeer)
+                return sk->sk_prot->twsk_prot->twsk_getpeer(sk);
+        return NULL;
+}
+
 #endif /* _TIMEWAIT_SOCK_H */
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0ddf819cfb5d..dd555051ec8b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1210,12 +1210,6 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
 };
 #endif
 
-static struct timewait_sock_ops tcp_timewait_sock_ops = {
-        .twsk_obj_size  = sizeof(struct tcp_timewait_sock),
-        .twsk_unique    = tcp_twsk_unique,
-        .twsk_destructor= tcp_twsk_destructor,
-};
-
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
         struct tcp_extend_values tmp_ext;
@@ -1783,25 +1777,20 @@ struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it)
 }
 EXPORT_SYMBOL(tcp_v4_get_peer);
 
-int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
+void *tcp_v4_tw_get_peer(struct sock *sk)
 {
-        struct inet_peer *peer = inet_getpeer_v4(tw->tw_daddr, 1);
-
-        if (peer) {
-                const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
-
-                if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
-                    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
-                     peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
-                        peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
-                        peer->tcp_ts       = tcptw->tw_ts_recent;
-                }
-                inet_putpeer(peer);
-                return 1;
-        }
+        struct inet_timewait_sock *tw = inet_twsk(sk);
 
-        return 0;
+        return inet_getpeer_v4(tw->tw_daddr, 1);
 }
+EXPORT_SYMBOL(tcp_v4_tw_get_peer);
+
+static struct timewait_sock_ops tcp_timewait_sock_ops = {
+        .twsk_obj_size  = sizeof(struct tcp_timewait_sock),
+        .twsk_unique    = tcp_twsk_unique,
+        .twsk_destructor= tcp_twsk_destructor,
+        .twsk_getpeer   = tcp_v4_tw_get_peer,
+};
 
 const struct inet_connection_sock_af_ops ipv4_specific = {
         .queue_xmit        = ip_queue_xmit,
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 059082c873cf..3527b51d6159 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -78,6 +78,27 @@ static int tcp_remember_stamp(struct sock *sk)
         return 0;
 }
 
+static int tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
+{
+        struct sock *sk = (struct sock *) tw;
+        struct inet_peer *peer;
+
+        peer = twsk_getpeer(sk);
+        if (peer) {
+                const struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+
+                if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
+                    ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL &&
+                     peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
+                        peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
+                        peer->tcp_ts       = tcptw->tw_ts_recent;
+                }
+                inet_putpeer(peer);
+                return 1;
+        }
+        return 0;
+}
+
 static __inline__ int tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
 {
         if (seq == s_win)
@@ -178,14 +199,9 @@ kill_with_rst:
                         tcptw->tw_ts_recent       = tmp_opt.rcv_tsval;
                 }
 
-                /* I am shamed, but failed to make it more elegant.
-                 * Yes, it is direct reference to IP, which is impossible
-                 * to generalize to IPv6. Taking into account that IPv6
-                 * do not understand recycling in any case, it not
-                 * a big problem in practice. --ANK */
-                if (tw->tw_family == AF_INET &&
-                    tcp_death_row.sysctl_tw_recycle && tcptw->tw_ts_recent_stamp &&
-                    tcp_v4_tw_remember_stamp(tw))
+                if (tcp_death_row.sysctl_tw_recycle &&
+                    tcptw->tw_ts_recent_stamp &&
+                    tcp_tw_remember_stamp(tw))
                         inet_twsk_schedule(tw, &tcp_death_row, tw->tw_timeout,
                                            TCP_TIMEWAIT_LEN);
                 else
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e394d0029d8d..5f73a1808e36 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -906,12 +906,6 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 };
 #endif
 
-static struct timewait_sock_ops tcp6_timewait_sock_ops = {
-        .twsk_obj_size  = sizeof(struct tcp6_timewait_sock),
-        .twsk_unique    = tcp_twsk_unique,
-        .twsk_destructor= tcp_twsk_destructor,
-};
-
 static void __tcp_v6_send_check(struct sk_buff *skb,
                                 struct in6_addr *saddr, struct in6_addr *daddr)
 {
@@ -1818,12 +1812,30 @@ do_time_wait:
         goto discard_it;
 }
 
-struct inet_peer *tcp_v6_get_peer(struct sock *sk, bool *release_it)
+static struct inet_peer *tcp_v6_get_peer(struct sock *sk, bool *release_it)
+{
+        /* Alas, not yet... */
+        return NULL;
+}
+
+static void *tcp_v6_tw_get_peer(struct sock *sk)
 {
+        struct inet_timewait_sock *tw = inet_twsk(sk);
+
+        if (tw->tw_family == AF_INET)
+                return tcp_v4_tw_get_peer(sk);
+
         /* Alas, not yet... */
         return NULL;
 }
 
+static struct timewait_sock_ops tcp6_timewait_sock_ops = {
+        .twsk_obj_size  = sizeof(struct tcp6_timewait_sock),
+        .twsk_unique    = tcp_twsk_unique,
+        .twsk_destructor= tcp_twsk_destructor,
+        .twsk_getpeer   = tcp_v6_tw_get_peer,
+};
+
 static const struct inet_connection_sock_af_ops ipv6_specific = {
         .queue_xmit        = inet6_csk_xmit,
         .send_check        = tcp_v6_send_check,