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 <[email protected]>

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);

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 */

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,

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 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
  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

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 @@ static int tcp_v6_rcv(struct sk_buff *skb)
  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,