inet: rename some inet_sock fields
[linux-2.6.git] / net / ipv4 / tcp_ipv4.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              Implementation of the Transmission Control Protocol(TCP).
7  *
8  *              IPv4 specific functions
9  *
10  *
11  *              code split from:
12  *              linux/ipv4/tcp.c
13  *              linux/ipv4/tcp_input.c
14  *              linux/ipv4/tcp_output.c
15  *
16  *              See tcp.c for author information
17  *
18  *      This program is free software; you can redistribute it and/or
19  *      modify it under the terms of the GNU General Public License
20  *      as published by the Free Software Foundation; either version
21  *      2 of the License, or (at your option) any later version.
22  */
23
24 /*
25  * Changes:
26  *              David S. Miller :       New socket lookup architecture.
27  *                                      This code is dedicated to John Dyson.
28  *              David S. Miller :       Change semantics of established hash,
29  *                                      half is devoted to TIME_WAIT sockets
30  *                                      and the rest go in the other half.
31  *              Andi Kleen :            Add support for syncookies and fixed
32  *                                      some bugs: ip options weren't passed to
33  *                                      the TCP layer, missed a check for an
34  *                                      ACK bit.
35  *              Andi Kleen :            Implemented fast path mtu discovery.
36  *                                      Fixed many serious bugs in the
37  *                                      request_sock handling and moved
38  *                                      most of it into the af independent code.
39  *                                      Added tail drop and some other bugfixes.
40  *                                      Added new listen semantics.
41  *              Mike McLagan    :       Routing by source
42  *      Juan Jose Ciarlante:            ip_dynaddr bits
43  *              Andi Kleen:             various fixes.
44  *      Vitaly E. Lavrov        :       Transparent proxy revived after year
45  *                                      coma.
46  *      Andi Kleen              :       Fix new listen.
47  *      Andi Kleen              :       Fix accept error reporting.
48  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
49  *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
50  *                                      a single port at the same time.
51  */
52
53
54 #include <linux/bottom_half.h>
55 #include <linux/types.h>
56 #include <linux/fcntl.h>
57 #include <linux/module.h>
58 #include <linux/random.h>
59 #include <linux/cache.h>
60 #include <linux/jhash.h>
61 #include <linux/init.h>
62 #include <linux/times.h>
63
64 #include <net/net_namespace.h>
65 #include <net/icmp.h>
66 #include <net/inet_hashtables.h>
67 #include <net/tcp.h>
68 #include <net/transp_v6.h>
69 #include <net/ipv6.h>
70 #include <net/inet_common.h>
71 #include <net/timewait_sock.h>
72 #include <net/xfrm.h>
73 #include <net/netdma.h>
74
75 #include <linux/inet.h>
76 #include <linux/ipv6.h>
77 #include <linux/stddef.h>
78 #include <linux/proc_fs.h>
79 #include <linux/seq_file.h>
80
81 #include <linux/crypto.h>
82 #include <linux/scatterlist.h>
83
84 int sysctl_tcp_tw_reuse __read_mostly;
85 int sysctl_tcp_low_latency __read_mostly;
86
87
88 #ifdef CONFIG_TCP_MD5SIG
89 static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
90                                                    __be32 addr);
91 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
92                                __be32 daddr, __be32 saddr, struct tcphdr *th);
93 #else
94 static inline
95 struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
96 {
97         return NULL;
98 }
99 #endif
100
101 struct inet_hashinfo tcp_hashinfo;
102
103 static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
104 {
105         return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
106                                           ip_hdr(skb)->saddr,
107                                           tcp_hdr(skb)->dest,
108                                           tcp_hdr(skb)->source);
109 }
110
111 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
112 {
113         const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
114         struct tcp_sock *tp = tcp_sk(sk);
115
116         /* With PAWS, it is safe from the viewpoint
117            of data integrity. Even without PAWS it is safe provided sequence
118            spaces do not overlap i.e. at data rates <= 80Mbit/sec.
119
120            Actually, the idea is close to VJ's one, only timestamp cache is
121            held not per host, but per port pair and TW bucket is used as state
122            holder.
123
124            If TW bucket has been already destroyed we fall back to VJ's scheme
125            and use initial timestamp retrieved from peer table.
126          */
127         if (tcptw->tw_ts_recent_stamp &&
128             (twp == NULL || (sysctl_tcp_tw_reuse &&
129                              get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
130                 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
131                 if (tp->write_seq == 0)
132                         tp->write_seq = 1;
133                 tp->rx_opt.ts_recent       = tcptw->tw_ts_recent;
134                 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
135                 sock_hold(sktw);
136                 return 1;
137         }
138
139         return 0;
140 }
141
142 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
143
144 /* This will initiate an outgoing connection. */
145 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
146 {
147         struct inet_sock *inet = inet_sk(sk);
148         struct tcp_sock *tp = tcp_sk(sk);
149         struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
150         struct rtable *rt;
151         __be32 daddr, nexthop;
152         int tmp;
153         int err;
154
155         if (addr_len < sizeof(struct sockaddr_in))
156                 return -EINVAL;
157
158         if (usin->sin_family != AF_INET)
159                 return -EAFNOSUPPORT;
160
161         nexthop = daddr = usin->sin_addr.s_addr;
162         if (inet->opt && inet->opt->srr) {
163                 if (!daddr)
164                         return -EINVAL;
165                 nexthop = inet->opt->faddr;
166         }
167
168         tmp = ip_route_connect(&rt, nexthop, inet->inet_saddr,
169                                RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
170                                IPPROTO_TCP,
171                                inet->inet_sport, usin->sin_port, sk, 1);
172         if (tmp < 0) {
173                 if (tmp == -ENETUNREACH)
174                         IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
175                 return tmp;
176         }
177
178         if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
179                 ip_rt_put(rt);
180                 return -ENETUNREACH;
181         }
182
183         if (!inet->opt || !inet->opt->srr)
184                 daddr = rt->rt_dst;
185
186         if (!inet->inet_saddr)
187                 inet->inet_saddr = rt->rt_src;
188         inet->inet_rcv_saddr = inet->inet_saddr;
189
190         if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
191                 /* Reset inherited state */
192                 tp->rx_opt.ts_recent       = 0;
193                 tp->rx_opt.ts_recent_stamp = 0;
194                 tp->write_seq              = 0;
195         }
196
197         if (tcp_death_row.sysctl_tw_recycle &&
198             !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
199                 struct inet_peer *peer = rt_get_peer(rt);
200                 /*
201                  * VJ's idea. We save last timestamp seen from
202                  * the destination in peer table, when entering state
203                  * TIME-WAIT * and initialize rx_opt.ts_recent from it,
204                  * when trying new connection.
205                  */
206                 if (peer != NULL &&
207                     peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {
208                         tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
209                         tp->rx_opt.ts_recent = peer->tcp_ts;
210                 }
211         }
212
213         inet->inet_dport = usin->sin_port;
214         inet->inet_daddr = daddr;
215
216         inet_csk(sk)->icsk_ext_hdr_len = 0;
217         if (inet->opt)
218                 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
219
220         tp->rx_opt.mss_clamp = 536;
221
222         /* Socket identity is still unknown (sport may be zero).
223          * However we set state to SYN-SENT and not releasing socket
224          * lock select source port, enter ourselves into the hash tables and
225          * complete initialization after this.
226          */
227         tcp_set_state(sk, TCP_SYN_SENT);
228         err = inet_hash_connect(&tcp_death_row, sk);
229         if (err)
230                 goto failure;
231
232         err = ip_route_newports(&rt, IPPROTO_TCP,
233                                 inet->inet_sport, inet->inet_dport, sk);
234         if (err)
235                 goto failure;
236
237         /* OK, now commit destination to socket.  */
238         sk->sk_gso_type = SKB_GSO_TCPV4;
239         sk_setup_caps(sk, &rt->u.dst);
240
241         if (!tp->write_seq)
242                 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
243                                                            inet->inet_daddr,
244                                                            inet->inet_sport,
245                                                            usin->sin_port);
246
247         inet->inet_id = tp->write_seq ^ jiffies;
248
249         err = tcp_connect(sk);
250         rt = NULL;
251         if (err)
252                 goto failure;
253
254         return 0;
255
256 failure:
257         /*
258          * This unhashes the socket and releases the local port,
259          * if necessary.
260          */
261         tcp_set_state(sk, TCP_CLOSE);
262         ip_rt_put(rt);
263         sk->sk_route_caps = 0;
264         inet->inet_dport = 0;
265         return err;
266 }
267
268 /*
269  * This routine does path mtu discovery as defined in RFC1191.
270  */
271 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu)
272 {
273         struct dst_entry *dst;
274         struct inet_sock *inet = inet_sk(sk);
275
276         /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
277          * send out by Linux are always <576bytes so they should go through
278          * unfragmented).
279          */
280         if (sk->sk_state == TCP_LISTEN)
281                 return;
282
283         /* We don't check in the destentry if pmtu discovery is forbidden
284          * on this route. We just assume that no packet_to_big packets
285          * are send back when pmtu discovery is not active.
286          * There is a small race when the user changes this flag in the
287          * route, but I think that's acceptable.
288          */
289         if ((dst = __sk_dst_check(sk, 0)) == NULL)
290                 return;
291
292         dst->ops->update_pmtu(dst, mtu);
293
294         /* Something is about to be wrong... Remember soft error
295          * for the case, if this connection will not able to recover.
296          */
297         if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
298                 sk->sk_err_soft = EMSGSIZE;
299
300         mtu = dst_mtu(dst);
301
302         if (inet->pmtudisc != IP_PMTUDISC_DONT &&
303             inet_csk(sk)->icsk_pmtu_cookie > mtu) {
304                 tcp_sync_mss(sk, mtu);
305
306                 /* Resend the TCP packet because it's
307                  * clear that the old packet has been
308                  * dropped. This is the new "fast" path mtu
309                  * discovery.
310                  */
311                 tcp_simple_retransmit(sk);
312         } /* else let the usual retransmit timer handle it */
313 }
314
315 /*
316  * This routine is called by the ICMP module when it gets some
317  * sort of error condition.  If err < 0 then the socket should
318  * be closed and the error returned to the user.  If err > 0
319  * it's just the icmp type << 8 | icmp code.  After adjustment
320  * header points to the first 8 bytes of the tcp header.  We need
321  * to find the appropriate port.
322  *
323  * The locking strategy used here is very "optimistic". When
324  * someone else accesses the socket the ICMP is just dropped
325  * and for some paths there is no check at all.
326  * A more general error queue to queue errors for later handling
327  * is probably better.
328  *
329  */
330
331 void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
332 {
333         struct iphdr *iph = (struct iphdr *)icmp_skb->data;
334         struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
335         struct inet_connection_sock *icsk;
336         struct tcp_sock *tp;
337         struct inet_sock *inet;
338         const int type = icmp_hdr(icmp_skb)->type;
339         const int code = icmp_hdr(icmp_skb)->code;
340         struct sock *sk;
341         struct sk_buff *skb;
342         __u32 seq;
343         __u32 remaining;
344         int err;
345         struct net *net = dev_net(icmp_skb->dev);
346
347         if (icmp_skb->len < (iph->ihl << 2) + 8) {
348                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
349                 return;
350         }
351
352         sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
353                         iph->saddr, th->source, inet_iif(icmp_skb));
354         if (!sk) {
355                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
356                 return;
357         }
358         if (sk->sk_state == TCP_TIME_WAIT) {
359                 inet_twsk_put(inet_twsk(sk));
360                 return;
361         }
362
363         bh_lock_sock(sk);
364         /* If too many ICMPs get dropped on busy
365          * servers this needs to be solved differently.
366          */
367         if (sock_owned_by_user(sk))
368                 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
369
370         if (sk->sk_state == TCP_CLOSE)
371                 goto out;
372
373         icsk = inet_csk(sk);
374         tp = tcp_sk(sk);
375         seq = ntohl(th->seq);
376         if (sk->sk_state != TCP_LISTEN &&
377             !between(seq, tp->snd_una, tp->snd_nxt)) {
378                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
379                 goto out;
380         }
381
382         switch (type) {
383         case ICMP_SOURCE_QUENCH:
384                 /* Just silently ignore these. */
385                 goto out;
386         case ICMP_PARAMETERPROB:
387                 err = EPROTO;
388                 break;
389         case ICMP_DEST_UNREACH:
390                 if (code > NR_ICMP_UNREACH)
391                         goto out;
392
393                 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
394                         if (!sock_owned_by_user(sk))
395                                 do_pmtu_discovery(sk, iph, info);
396                         goto out;
397                 }
398
399                 err = icmp_err_convert[code].errno;
400                 /* check if icmp_skb allows revert of backoff
401                  * (see draft-zimmermann-tcp-lcd) */
402                 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
403                         break;
404                 if (seq != tp->snd_una  || !icsk->icsk_retransmits ||
405                     !icsk->icsk_backoff)
406                         break;
407
408                 icsk->icsk_backoff--;
409                 inet_csk(sk)->icsk_rto = __tcp_set_rto(tp) <<
410                                          icsk->icsk_backoff;
411                 tcp_bound_rto(sk);
412
413                 skb = tcp_write_queue_head(sk);
414                 BUG_ON(!skb);
415
416                 remaining = icsk->icsk_rto - min(icsk->icsk_rto,
417                                 tcp_time_stamp - TCP_SKB_CB(skb)->when);
418
419                 if (remaining) {
420                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
421                                                   remaining, TCP_RTO_MAX);
422                 } else if (sock_owned_by_user(sk)) {
423                         /* RTO revert clocked out retransmission,
424                          * but socket is locked. Will defer. */
425                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
426                                                   HZ/20, TCP_RTO_MAX);
427                 } else {
428                         /* RTO revert clocked out retransmission.
429                          * Will retransmit now */
430                         tcp_retransmit_timer(sk);
431                 }
432
433                 break;
434         case ICMP_TIME_EXCEEDED:
435                 err = EHOSTUNREACH;
436                 break;
437         default:
438                 goto out;
439         }
440
441         switch (sk->sk_state) {
442                 struct request_sock *req, **prev;
443         case TCP_LISTEN:
444                 if (sock_owned_by_user(sk))
445                         goto out;
446
447                 req = inet_csk_search_req(sk, &prev, th->dest,
448                                           iph->daddr, iph->saddr);
449                 if (!req)
450                         goto out;
451
452                 /* ICMPs are not backlogged, hence we cannot get
453                    an established socket here.
454                  */
455                 WARN_ON(req->sk);
456
457                 if (seq != tcp_rsk(req)->snt_isn) {
458                         NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
459                         goto out;
460                 }
461
462                 /*
463                  * Still in SYN_RECV, just remove it silently.
464                  * There is no good way to pass the error to the newly
465                  * created socket, and POSIX does not want network
466                  * errors returned from accept().
467                  */
468                 inet_csk_reqsk_queue_drop(sk, req, prev);
469                 goto out;
470
471         case TCP_SYN_SENT:
472         case TCP_SYN_RECV:  /* Cannot happen.
473                                It can f.e. if SYNs crossed.
474                              */
475                 if (!sock_owned_by_user(sk)) {
476                         sk->sk_err = err;
477
478                         sk->sk_error_report(sk);
479
480                         tcp_done(sk);
481                 } else {
482                         sk->sk_err_soft = err;
483                 }
484                 goto out;
485         }
486
487         /* If we've already connected we will keep trying
488          * until we time out, or the user gives up.
489          *
490          * rfc1122 4.2.3.9 allows to consider as hard errors
491          * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
492          * but it is obsoleted by pmtu discovery).
493          *
494          * Note, that in modern internet, where routing is unreliable
495          * and in each dark corner broken firewalls sit, sending random
496          * errors ordered by their masters even this two messages finally lose
497          * their original sense (even Linux sends invalid PORT_UNREACHs)
498          *
499          * Now we are in compliance with RFCs.
500          *                                                      --ANK (980905)
501          */
502
503         inet = inet_sk(sk);
504         if (!sock_owned_by_user(sk) && inet->recverr) {
505                 sk->sk_err = err;
506                 sk->sk_error_report(sk);
507         } else  { /* Only an error on timeout */
508                 sk->sk_err_soft = err;
509         }
510
511 out:
512         bh_unlock_sock(sk);
513         sock_put(sk);
514 }
515
516 /* This routine computes an IPv4 TCP checksum. */
517 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
518 {
519         struct inet_sock *inet = inet_sk(sk);
520         struct tcphdr *th = tcp_hdr(skb);
521
522         if (skb->ip_summed == CHECKSUM_PARTIAL) {
523                 th->check = ~tcp_v4_check(len, inet->inet_saddr,
524                                           inet->inet_daddr, 0);
525                 skb->csum_start = skb_transport_header(skb) - skb->head;
526                 skb->csum_offset = offsetof(struct tcphdr, check);
527         } else {
528                 th->check = tcp_v4_check(len, inet->inet_saddr,
529                                          inet->inet_daddr,
530                                          csum_partial(th,
531                                                       th->doff << 2,
532                                                       skb->csum));
533         }
534 }
535
536 int tcp_v4_gso_send_check(struct sk_buff *skb)
537 {
538         const struct iphdr *iph;
539         struct tcphdr *th;
540
541         if (!pskb_may_pull(skb, sizeof(*th)))
542                 return -EINVAL;
543
544         iph = ip_hdr(skb);
545         th = tcp_hdr(skb);
546
547         th->check = 0;
548         th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0);
549         skb->csum_start = skb_transport_header(skb) - skb->head;
550         skb->csum_offset = offsetof(struct tcphdr, check);
551         skb->ip_summed = CHECKSUM_PARTIAL;
552         return 0;
553 }
554
555 /*
556  *      This routine will send an RST to the other tcp.
557  *
558  *      Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
559  *                    for reset.
560  *      Answer: if a packet caused RST, it is not for a socket
561  *              existing in our system, if it is matched to a socket,
562  *              it is just duplicate segment or bug in other side's TCP.
563  *              So that we build reply only basing on parameters
564  *              arrived with segment.
565  *      Exception: precedence violation. We do not implement it in any case.
566  */
567
568 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
569 {
570         struct tcphdr *th = tcp_hdr(skb);
571         struct {
572                 struct tcphdr th;
573 #ifdef CONFIG_TCP_MD5SIG
574                 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
575 #endif
576         } rep;
577         struct ip_reply_arg arg;
578 #ifdef CONFIG_TCP_MD5SIG
579         struct tcp_md5sig_key *key;
580 #endif
581         struct net *net;
582
583         /* Never send a reset in response to a reset. */
584         if (th->rst)
585                 return;
586
587         if (skb_rtable(skb)->rt_type != RTN_LOCAL)
588                 return;
589
590         /* Swap the send and the receive. */
591         memset(&rep, 0, sizeof(rep));
592         rep.th.dest   = th->source;
593         rep.th.source = th->dest;
594         rep.th.doff   = sizeof(struct tcphdr) / 4;
595         rep.th.rst    = 1;
596
597         if (th->ack) {
598                 rep.th.seq = th->ack_seq;
599         } else {
600                 rep.th.ack = 1;
601                 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
602                                        skb->len - (th->doff << 2));
603         }
604
605         memset(&arg, 0, sizeof(arg));
606         arg.iov[0].iov_base = (unsigned char *)&rep;
607         arg.iov[0].iov_len  = sizeof(rep.th);
608
609 #ifdef CONFIG_TCP_MD5SIG
610         key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
611         if (key) {
612                 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
613                                    (TCPOPT_NOP << 16) |
614                                    (TCPOPT_MD5SIG << 8) |
615                                    TCPOLEN_MD5SIG);
616                 /* Update length and the length the header thinks exists */
617                 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
618                 rep.th.doff = arg.iov[0].iov_len / 4;
619
620                 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
621                                      key, ip_hdr(skb)->saddr,
622                                      ip_hdr(skb)->daddr, &rep.th);
623         }
624 #endif
625         arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
626                                       ip_hdr(skb)->saddr, /* XXX */
627                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
628         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
629         arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
630
631         net = dev_net(skb_dst(skb)->dev);
632         ip_send_reply(net->ipv4.tcp_sock, skb,
633                       &arg, arg.iov[0].iov_len);
634
635         TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
636         TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
637 }
638
639 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
640    outside socket context is ugly, certainly. What can I do?
641  */
642
643 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
644                             u32 win, u32 ts, int oif,
645                             struct tcp_md5sig_key *key,
646                             int reply_flags)
647 {
648         struct tcphdr *th = tcp_hdr(skb);
649         struct {
650                 struct tcphdr th;
651                 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
652 #ifdef CONFIG_TCP_MD5SIG
653                            + (TCPOLEN_MD5SIG_ALIGNED >> 2)
654 #endif
655                         ];
656         } rep;
657         struct ip_reply_arg arg;
658         struct net *net = dev_net(skb_dst(skb)->dev);
659
660         memset(&rep.th, 0, sizeof(struct tcphdr));
661         memset(&arg, 0, sizeof(arg));
662
663         arg.iov[0].iov_base = (unsigned char *)&rep;
664         arg.iov[0].iov_len  = sizeof(rep.th);
665         if (ts) {
666                 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
667                                    (TCPOPT_TIMESTAMP << 8) |
668                                    TCPOLEN_TIMESTAMP);
669                 rep.opt[1] = htonl(tcp_time_stamp);
670                 rep.opt[2] = htonl(ts);
671                 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
672         }
673
674         /* Swap the send and the receive. */
675         rep.th.dest    = th->source;
676         rep.th.source  = th->dest;
677         rep.th.doff    = arg.iov[0].iov_len / 4;
678         rep.th.seq     = htonl(seq);
679         rep.th.ack_seq = htonl(ack);
680         rep.th.ack     = 1;
681         rep.th.window  = htons(win);
682
683 #ifdef CONFIG_TCP_MD5SIG
684         if (key) {
685                 int offset = (ts) ? 3 : 0;
686
687                 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
688                                           (TCPOPT_NOP << 16) |
689                                           (TCPOPT_MD5SIG << 8) |
690                                           TCPOLEN_MD5SIG);
691                 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
692                 rep.th.doff = arg.iov[0].iov_len/4;
693
694                 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
695                                     key, ip_hdr(skb)->saddr,
696                                     ip_hdr(skb)->daddr, &rep.th);
697         }
698 #endif
699         arg.flags = reply_flags;
700         arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
701                                       ip_hdr(skb)->saddr, /* XXX */
702                                       arg.iov[0].iov_len, IPPROTO_TCP, 0);
703         arg.csumoffset = offsetof(struct tcphdr, check) / 2;
704         if (oif)
705                 arg.bound_dev_if = oif;
706
707         ip_send_reply(net->ipv4.tcp_sock, skb,
708                       &arg, arg.iov[0].iov_len);
709
710         TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
711 }
712
713 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
714 {
715         struct inet_timewait_sock *tw = inet_twsk(sk);
716         struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
717
718         tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
719                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
720                         tcptw->tw_ts_recent,
721                         tw->tw_bound_dev_if,
722                         tcp_twsk_md5_key(tcptw),
723                         tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0
724                         );
725
726         inet_twsk_put(tw);
727 }
728
729 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
730                                   struct request_sock *req)
731 {
732         tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
733                         tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
734                         req->ts_recent,
735                         0,
736                         tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr),
737                         inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0);
738 }
739
740 /*
741  *      Send a SYN-ACK after having received a SYN.
742  *      This still operates on a request_sock only, not on a big
743  *      socket.
744  */
745 static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
746                                 struct dst_entry *dst)
747 {
748         const struct inet_request_sock *ireq = inet_rsk(req);
749         int err = -1;
750         struct sk_buff * skb;
751
752         /* First, grab a route. */
753         if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
754                 return -1;
755
756         skb = tcp_make_synack(sk, dst, req);
757
758         if (skb) {
759                 struct tcphdr *th = tcp_hdr(skb);
760
761                 th->check = tcp_v4_check(skb->len,
762                                          ireq->loc_addr,
763                                          ireq->rmt_addr,
764                                          csum_partial(th, skb->len,
765                                                       skb->csum));
766
767                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
768                                             ireq->rmt_addr,
769                                             ireq->opt);
770                 err = net_xmit_eval(err);
771         }
772
773         dst_release(dst);
774         return err;
775 }
776
777 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req)
778 {
779         return __tcp_v4_send_synack(sk, req, NULL);
780 }
781
782 /*
783  *      IPv4 request_sock destructor.
784  */
785 static void tcp_v4_reqsk_destructor(struct request_sock *req)
786 {
787         kfree(inet_rsk(req)->opt);
788 }
789
790 #ifdef CONFIG_SYN_COOKIES
791 static void syn_flood_warning(struct sk_buff *skb)
792 {
793         static unsigned long warntime;
794
795         if (time_after(jiffies, (warntime + HZ * 60))) {
796                 warntime = jiffies;
797                 printk(KERN_INFO
798                        "possible SYN flooding on port %d. Sending cookies.\n",
799                        ntohs(tcp_hdr(skb)->dest));
800         }
801 }
802 #endif
803
804 /*
805  * Save and compile IPv4 options into the request_sock if needed.
806  */
807 static struct ip_options *tcp_v4_save_options(struct sock *sk,
808                                               struct sk_buff *skb)
809 {
810         struct ip_options *opt = &(IPCB(skb)->opt);
811         struct ip_options *dopt = NULL;
812
813         if (opt && opt->optlen) {
814                 int opt_size = optlength(opt);
815                 dopt = kmalloc(opt_size, GFP_ATOMIC);
816                 if (dopt) {
817                         if (ip_options_echo(dopt, skb)) {
818                                 kfree(dopt);
819                                 dopt = NULL;
820                         }
821                 }
822         }
823         return dopt;
824 }
825
826 #ifdef CONFIG_TCP_MD5SIG
827 /*
828  * RFC2385 MD5 checksumming requires a mapping of
829  * IP address->MD5 Key.
830  * We need to maintain these in the sk structure.
831  */
832
833 /* Find the Key structure for an address.  */
834 static struct tcp_md5sig_key *
835                         tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
836 {
837         struct tcp_sock *tp = tcp_sk(sk);
838         int i;
839
840         if (!tp->md5sig_info || !tp->md5sig_info->entries4)
841                 return NULL;
842         for (i = 0; i < tp->md5sig_info->entries4; i++) {
843                 if (tp->md5sig_info->keys4[i].addr == addr)
844                         return &tp->md5sig_info->keys4[i].base;
845         }
846         return NULL;
847 }
848
849 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
850                                          struct sock *addr_sk)
851 {
852         return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->inet_daddr);
853 }
854
855 EXPORT_SYMBOL(tcp_v4_md5_lookup);
856
857 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
858                                                       struct request_sock *req)
859 {
860         return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
861 }
862
863 /* This can be called on a newly created socket, from other files */
864 int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
865                       u8 *newkey, u8 newkeylen)
866 {
867         /* Add Key to the list */
868         struct tcp_md5sig_key *key;
869         struct tcp_sock *tp = tcp_sk(sk);
870         struct tcp4_md5sig_key *keys;
871
872         key = tcp_v4_md5_do_lookup(sk, addr);
873         if (key) {
874                 /* Pre-existing entry - just update that one. */
875                 kfree(key->key);
876                 key->key = newkey;
877                 key->keylen = newkeylen;
878         } else {
879                 struct tcp_md5sig_info *md5sig;
880
881                 if (!tp->md5sig_info) {
882                         tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
883                                                   GFP_ATOMIC);
884                         if (!tp->md5sig_info) {
885                                 kfree(newkey);
886                                 return -ENOMEM;
887                         }
888                         sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
889                 }
890                 if (tcp_alloc_md5sig_pool(sk) == NULL) {
891                         kfree(newkey);
892                         return -ENOMEM;
893                 }
894                 md5sig = tp->md5sig_info;
895
896                 if (md5sig->alloced4 == md5sig->entries4) {
897                         keys = kmalloc((sizeof(*keys) *
898                                         (md5sig->entries4 + 1)), GFP_ATOMIC);
899                         if (!keys) {
900                                 kfree(newkey);
901                                 tcp_free_md5sig_pool();
902                                 return -ENOMEM;
903                         }
904
905                         if (md5sig->entries4)
906                                 memcpy(keys, md5sig->keys4,
907                                        sizeof(*keys) * md5sig->entries4);
908
909                         /* Free old key list, and reference new one */
910                         kfree(md5sig->keys4);
911                         md5sig->keys4 = keys;
912                         md5sig->alloced4++;
913                 }
914                 md5sig->entries4++;
915                 md5sig->keys4[md5sig->entries4 - 1].addr        = addr;
916                 md5sig->keys4[md5sig->entries4 - 1].base.key    = newkey;
917                 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
918         }
919         return 0;
920 }
921
922 EXPORT_SYMBOL(tcp_v4_md5_do_add);
923
924 static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
925                                u8 *newkey, u8 newkeylen)
926 {
927         return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->inet_daddr,
928                                  newkey, newkeylen);
929 }
930
931 int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
932 {
933         struct tcp_sock *tp = tcp_sk(sk);
934         int i;
935
936         for (i = 0; i < tp->md5sig_info->entries4; i++) {
937                 if (tp->md5sig_info->keys4[i].addr == addr) {
938                         /* Free the key */
939                         kfree(tp->md5sig_info->keys4[i].base.key);
940                         tp->md5sig_info->entries4--;
941
942                         if (tp->md5sig_info->entries4 == 0) {
943                                 kfree(tp->md5sig_info->keys4);
944                                 tp->md5sig_info->keys4 = NULL;
945                                 tp->md5sig_info->alloced4 = 0;
946                         } else if (tp->md5sig_info->entries4 != i) {
947                                 /* Need to do some manipulation */
948                                 memmove(&tp->md5sig_info->keys4[i],
949                                         &tp->md5sig_info->keys4[i+1],
950                                         (tp->md5sig_info->entries4 - i) *
951                                          sizeof(struct tcp4_md5sig_key));
952                         }
953                         tcp_free_md5sig_pool();
954                         return 0;
955                 }
956         }
957         return -ENOENT;
958 }
959
960 EXPORT_SYMBOL(tcp_v4_md5_do_del);
961
962 static void tcp_v4_clear_md5_list(struct sock *sk)
963 {
964         struct tcp_sock *tp = tcp_sk(sk);
965
966         /* Free each key, then the set of key keys,
967          * the crypto element, and then decrement our
968          * hold on the last resort crypto.
969          */
970         if (tp->md5sig_info->entries4) {
971                 int i;
972                 for (i = 0; i < tp->md5sig_info->entries4; i++)
973                         kfree(tp->md5sig_info->keys4[i].base.key);
974                 tp->md5sig_info->entries4 = 0;
975                 tcp_free_md5sig_pool();
976         }
977         if (tp->md5sig_info->keys4) {
978                 kfree(tp->md5sig_info->keys4);
979                 tp->md5sig_info->keys4 = NULL;
980                 tp->md5sig_info->alloced4  = 0;
981         }
982 }
983
984 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
985                                  int optlen)
986 {
987         struct tcp_md5sig cmd;
988         struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
989         u8 *newkey;
990
991         if (optlen < sizeof(cmd))
992                 return -EINVAL;
993
994         if (copy_from_user(&cmd, optval, sizeof(cmd)))
995                 return -EFAULT;
996
997         if (sin->sin_family != AF_INET)
998                 return -EINVAL;
999
1000         if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
1001                 if (!tcp_sk(sk)->md5sig_info)
1002                         return -ENOENT;
1003                 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
1004         }
1005
1006         if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1007                 return -EINVAL;
1008
1009         if (!tcp_sk(sk)->md5sig_info) {
1010                 struct tcp_sock *tp = tcp_sk(sk);
1011                 struct tcp_md5sig_info *p;
1012
1013                 p = kzalloc(sizeof(*p), sk->sk_allocation);
1014                 if (!p)
1015                         return -EINVAL;
1016
1017                 tp->md5sig_info = p;
1018                 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1019         }
1020
1021         newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, sk->sk_allocation);
1022         if (!newkey)
1023                 return -ENOMEM;
1024         return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
1025                                  newkey, cmd.tcpm_keylen);
1026 }
1027
1028 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1029                                         __be32 daddr, __be32 saddr, int nbytes)
1030 {
1031         struct tcp4_pseudohdr *bp;
1032         struct scatterlist sg;
1033
1034         bp = &hp->md5_blk.ip4;
1035
1036         /*
1037          * 1. the TCP pseudo-header (in the order: source IP address,
1038          * destination IP address, zero-padded protocol number, and
1039          * segment length)
1040          */
1041         bp->saddr = saddr;
1042         bp->daddr = daddr;
1043         bp->pad = 0;
1044         bp->protocol = IPPROTO_TCP;
1045         bp->len = cpu_to_be16(nbytes);
1046
1047         sg_init_one(&sg, bp, sizeof(*bp));
1048         return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1049 }
1050
1051 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
1052                                __be32 daddr, __be32 saddr, struct tcphdr *th)
1053 {
1054         struct tcp_md5sig_pool *hp;
1055         struct hash_desc *desc;
1056
1057         hp = tcp_get_md5sig_pool();
1058         if (!hp)
1059                 goto clear_hash_noput;
1060         desc = &hp->md5_desc;
1061
1062         if (crypto_hash_init(desc))
1063                 goto clear_hash;
1064         if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1065                 goto clear_hash;
1066         if (tcp_md5_hash_header(hp, th))
1067                 goto clear_hash;
1068         if (tcp_md5_hash_key(hp, key))
1069                 goto clear_hash;
1070         if (crypto_hash_final(desc, md5_hash))
1071                 goto clear_hash;
1072
1073         tcp_put_md5sig_pool();
1074         return 0;
1075
1076 clear_hash:
1077         tcp_put_md5sig_pool();
1078 clear_hash_noput:
1079         memset(md5_hash, 0, 16);
1080         return 1;
1081 }
1082
1083 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1084                         struct sock *sk, struct request_sock *req,
1085                         struct sk_buff *skb)
1086 {
1087         struct tcp_md5sig_pool *hp;
1088         struct hash_desc *desc;
1089         struct tcphdr *th = tcp_hdr(skb);
1090         __be32 saddr, daddr;
1091
1092         if (sk) {
1093                 saddr = inet_sk(sk)->inet_saddr;
1094                 daddr = inet_sk(sk)->inet_daddr;
1095         } else if (req) {
1096                 saddr = inet_rsk(req)->loc_addr;
1097                 daddr = inet_rsk(req)->rmt_addr;
1098         } else {
1099                 const struct iphdr *iph = ip_hdr(skb);
1100                 saddr = iph->saddr;
1101                 daddr = iph->daddr;
1102         }
1103
1104         hp = tcp_get_md5sig_pool();
1105         if (!hp)
1106                 goto clear_hash_noput;
1107         desc = &hp->md5_desc;
1108
1109         if (crypto_hash_init(desc))
1110                 goto clear_hash;
1111
1112         if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1113                 goto clear_hash;
1114         if (tcp_md5_hash_header(hp, th))
1115                 goto clear_hash;
1116         if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1117                 goto clear_hash;
1118         if (tcp_md5_hash_key(hp, key))
1119                 goto clear_hash;
1120         if (crypto_hash_final(desc, md5_hash))
1121                 goto clear_hash;
1122
1123         tcp_put_md5sig_pool();
1124         return 0;
1125
1126 clear_hash:
1127         tcp_put_md5sig_pool();
1128 clear_hash_noput:
1129         memset(md5_hash, 0, 16);
1130         return 1;
1131 }
1132
1133 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1134
1135 static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1136 {
1137         /*
1138          * This gets called for each TCP segment that arrives
1139          * so we want to be efficient.
1140          * We have 3 drop cases:
1141          * o No MD5 hash and one expected.
1142          * o MD5 hash and we're not expecting one.
1143          * o MD5 hash and its wrong.
1144          */
1145         __u8 *hash_location = NULL;
1146         struct tcp_md5sig_key *hash_expected;
1147         const struct iphdr *iph = ip_hdr(skb);
1148         struct tcphdr *th = tcp_hdr(skb);
1149         int genhash;
1150         unsigned char newhash[16];
1151
1152         hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1153         hash_location = tcp_parse_md5sig_option(th);
1154
1155         /* We've parsed the options - do we have a hash? */
1156         if (!hash_expected && !hash_location)
1157                 return 0;
1158
1159         if (hash_expected && !hash_location) {
1160                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1161                 return 1;
1162         }
1163
1164         if (!hash_expected && hash_location) {
1165                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1166                 return 1;
1167         }
1168
1169         /* Okay, so this is hash_expected and hash_location -
1170          * so we need to calculate the checksum.
1171          */
1172         genhash = tcp_v4_md5_hash_skb(newhash,
1173                                       hash_expected,
1174                                       NULL, NULL, skb);
1175
1176         if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1177                 if (net_ratelimit()) {
1178                         printk(KERN_INFO "MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1179                                &iph->saddr, ntohs(th->source),
1180                                &iph->daddr, ntohs(th->dest),
1181                                genhash ? " tcp_v4_calc_md5_hash failed" : "");
1182                 }
1183                 return 1;
1184         }
1185         return 0;
1186 }
1187
1188 #endif
1189
1190 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1191         .family         =       PF_INET,
1192         .obj_size       =       sizeof(struct tcp_request_sock),
1193         .rtx_syn_ack    =       tcp_v4_send_synack,
1194         .send_ack       =       tcp_v4_reqsk_send_ack,
1195         .destructor     =       tcp_v4_reqsk_destructor,
1196         .send_reset     =       tcp_v4_send_reset,
1197 };
1198
1199 #ifdef CONFIG_TCP_MD5SIG
1200 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1201         .md5_lookup     =       tcp_v4_reqsk_md5_lookup,
1202         .calc_md5_hash  =       tcp_v4_md5_hash_skb,
1203 };
1204 #endif
1205
1206 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1207         .twsk_obj_size  = sizeof(struct tcp_timewait_sock),
1208         .twsk_unique    = tcp_twsk_unique,
1209         .twsk_destructor= tcp_twsk_destructor,
1210 };
1211
1212 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1213 {
1214         struct inet_request_sock *ireq;
1215         struct tcp_options_received tmp_opt;
1216         struct request_sock *req;
1217         __be32 saddr = ip_hdr(skb)->saddr;
1218         __be32 daddr = ip_hdr(skb)->daddr;
1219         __u32 isn = TCP_SKB_CB(skb)->when;
1220         struct dst_entry *dst = NULL;
1221 #ifdef CONFIG_SYN_COOKIES
1222         int want_cookie = 0;
1223 #else
1224 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
1225 #endif
1226
1227         /* Never answer to SYNs send to broadcast or multicast */
1228         if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1229                 goto drop;
1230
1231         /* TW buckets are converted to open requests without
1232          * limitations, they conserve resources and peer is
1233          * evidently real one.
1234          */
1235         if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1236 #ifdef CONFIG_SYN_COOKIES
1237                 if (sysctl_tcp_syncookies) {
1238                         want_cookie = 1;
1239                 } else
1240 #endif
1241                 goto drop;
1242         }
1243
1244         /* Accept backlog is full. If we have already queued enough
1245          * of warm entries in syn queue, drop request. It is better than
1246          * clogging syn queue with openreqs with exponentially increasing
1247          * timeout.
1248          */
1249         if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1250                 goto drop;
1251
1252         req = inet_reqsk_alloc(&tcp_request_sock_ops);
1253         if (!req)
1254                 goto drop;
1255
1256 #ifdef CONFIG_TCP_MD5SIG
1257         tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1258 #endif
1259
1260         tcp_clear_options(&tmp_opt);
1261         tmp_opt.mss_clamp = 536;
1262         tmp_opt.user_mss  = tcp_sk(sk)->rx_opt.user_mss;
1263
1264         tcp_parse_options(skb, &tmp_opt, 0);
1265
1266         if (want_cookie && !tmp_opt.saw_tstamp)
1267                 tcp_clear_options(&tmp_opt);
1268
1269         tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1270
1271         tcp_openreq_init(req, &tmp_opt, skb);
1272
1273         ireq = inet_rsk(req);
1274         ireq->loc_addr = daddr;
1275         ireq->rmt_addr = saddr;
1276         ireq->no_srccheck = inet_sk(sk)->transparent;
1277         ireq->opt = tcp_v4_save_options(sk, skb);
1278
1279         if (security_inet_conn_request(sk, skb, req))
1280                 goto drop_and_free;
1281
1282         if (!want_cookie)
1283                 TCP_ECN_create_request(req, tcp_hdr(skb));
1284
1285         if (want_cookie) {
1286 #ifdef CONFIG_SYN_COOKIES
1287                 syn_flood_warning(skb);
1288                 req->cookie_ts = tmp_opt.tstamp_ok;
1289 #endif
1290                 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1291         } else if (!isn) {
1292                 struct inet_peer *peer = NULL;
1293
1294                 /* VJ's idea. We save last timestamp seen
1295                  * from the destination in peer table, when entering
1296                  * state TIME-WAIT, and check against it before
1297                  * accepting new connection request.
1298                  *
1299                  * If "isn" is not zero, this request hit alive
1300                  * timewait bucket, so that all the necessary checks
1301                  * are made in the function processing timewait state.
1302                  */
1303                 if (tmp_opt.saw_tstamp &&
1304                     tcp_death_row.sysctl_tw_recycle &&
1305                     (dst = inet_csk_route_req(sk, req)) != NULL &&
1306                     (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1307                     peer->v4daddr == saddr) {
1308                         if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1309                             (s32)(peer->tcp_ts - req->ts_recent) >
1310                                                         TCP_PAWS_WINDOW) {
1311                                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1312                                 goto drop_and_release;
1313                         }
1314                 }
1315                 /* Kill the following clause, if you dislike this way. */
1316                 else if (!sysctl_tcp_syncookies &&
1317                          (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1318                           (sysctl_max_syn_backlog >> 2)) &&
1319                          (!peer || !peer->tcp_ts_stamp) &&
1320                          (!dst || !dst_metric(dst, RTAX_RTT))) {
1321                         /* Without syncookies last quarter of
1322                          * backlog is filled with destinations,
1323                          * proven to be alive.
1324                          * It means that we continue to communicate
1325                          * to destinations, already remembered
1326                          * to the moment of synflood.
1327                          */
1328                         LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
1329                                        &saddr, ntohs(tcp_hdr(skb)->source));
1330                         goto drop_and_release;
1331                 }
1332
1333                 isn = tcp_v4_init_sequence(skb);
1334         }
1335         tcp_rsk(req)->snt_isn = isn;
1336
1337         if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
1338                 goto drop_and_free;
1339
1340         inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1341         return 0;
1342
1343 drop_and_release:
1344         dst_release(dst);
1345 drop_and_free:
1346         reqsk_free(req);
1347 drop:
1348         return 0;
1349 }
1350
1351
1352 /*
1353  * The three way handshake has completed - we got a valid synack -
1354  * now create the new socket.
1355  */
1356 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1357                                   struct request_sock *req,
1358                                   struct dst_entry *dst)
1359 {
1360         struct inet_request_sock *ireq;
1361         struct inet_sock *newinet;
1362         struct tcp_sock *newtp;
1363         struct sock *newsk;
1364 #ifdef CONFIG_TCP_MD5SIG
1365         struct tcp_md5sig_key *key;
1366 #endif
1367
1368         if (sk_acceptq_is_full(sk))
1369                 goto exit_overflow;
1370
1371         if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1372                 goto exit;
1373
1374         newsk = tcp_create_openreq_child(sk, req, skb);
1375         if (!newsk)
1376                 goto exit;
1377
1378         newsk->sk_gso_type = SKB_GSO_TCPV4;
1379         sk_setup_caps(newsk, dst);
1380
1381         newtp                 = tcp_sk(newsk);
1382         newinet               = inet_sk(newsk);
1383         ireq                  = inet_rsk(req);
1384         newinet->inet_daddr   = ireq->rmt_addr;
1385         newinet->inet_rcv_saddr = ireq->loc_addr;
1386         newinet->inet_saddr           = ireq->loc_addr;
1387         newinet->opt          = ireq->opt;
1388         ireq->opt             = NULL;
1389         newinet->mc_index     = inet_iif(skb);
1390         newinet->mc_ttl       = ip_hdr(skb)->ttl;
1391         inet_csk(newsk)->icsk_ext_hdr_len = 0;
1392         if (newinet->opt)
1393                 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1394         newinet->inet_id = newtp->write_seq ^ jiffies;
1395
1396         tcp_mtup_init(newsk);
1397         tcp_sync_mss(newsk, dst_mtu(dst));
1398         newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1399         if (tcp_sk(sk)->rx_opt.user_mss &&
1400             tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1401                 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1402
1403         tcp_initialize_rcv_mss(newsk);
1404
1405 #ifdef CONFIG_TCP_MD5SIG
1406         /* Copy over the MD5 key from the original socket */
1407         key = tcp_v4_md5_do_lookup(sk, newinet->inet_daddr);
1408         if (key != NULL) {
1409                 /*
1410                  * We're using one, so create a matching key
1411                  * on the newsk structure. If we fail to get
1412                  * memory, then we end up not copying the key
1413                  * across. Shucks.
1414                  */
1415                 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1416                 if (newkey != NULL)
1417                         tcp_v4_md5_do_add(newsk, newinet->inet_daddr,
1418                                           newkey, key->keylen);
1419                 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1420         }
1421 #endif
1422
1423         __inet_hash_nolisten(newsk);
1424         __inet_inherit_port(sk, newsk);
1425
1426         return newsk;
1427
1428 exit_overflow:
1429         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1430 exit:
1431         NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1432         dst_release(dst);
1433         return NULL;
1434 }
1435
1436 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1437 {
1438         struct tcphdr *th = tcp_hdr(skb);
1439         const struct iphdr *iph = ip_hdr(skb);
1440         struct sock *nsk;
1441         struct request_sock **prev;
1442         /* Find possible connection requests. */
1443         struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1444                                                        iph->saddr, iph->daddr);
1445         if (req)
1446                 return tcp_check_req(sk, skb, req, prev);
1447
1448         nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1449                         th->source, iph->daddr, th->dest, inet_iif(skb));
1450
1451         if (nsk) {
1452                 if (nsk->sk_state != TCP_TIME_WAIT) {
1453                         bh_lock_sock(nsk);
1454                         return nsk;
1455                 }
1456                 inet_twsk_put(inet_twsk(nsk));
1457                 return NULL;
1458         }
1459
1460 #ifdef CONFIG_SYN_COOKIES
1461         if (!th->rst && !th->syn && th->ack)
1462                 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1463 #endif
1464         return sk;
1465 }
1466
1467 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1468 {
1469         const struct iphdr *iph = ip_hdr(skb);
1470
1471         if (skb->ip_summed == CHECKSUM_COMPLETE) {
1472                 if (!tcp_v4_check(skb->len, iph->saddr,
1473                                   iph->daddr, skb->csum)) {
1474                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1475                         return 0;
1476                 }
1477         }
1478
1479         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1480                                        skb->len, IPPROTO_TCP, 0);
1481
1482         if (skb->len <= 76) {
1483                 return __skb_checksum_complete(skb);
1484         }
1485         return 0;
1486 }
1487
1488
1489 /* The socket must have it's spinlock held when we get
1490  * here.
1491  *
1492  * We have a potential double-lock case here, so even when
1493  * doing backlog processing we use the BH locking scheme.
1494  * This is because we cannot sleep with the original spinlock
1495  * held.
1496  */
1497 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1498 {
1499         struct sock *rsk;
1500 #ifdef CONFIG_TCP_MD5SIG
1501         /*
1502          * We really want to reject the packet as early as possible
1503          * if:
1504          *  o We're expecting an MD5'd packet and this is no MD5 tcp option
1505          *  o There is an MD5 option and we're not expecting one
1506          */
1507         if (tcp_v4_inbound_md5_hash(sk, skb))
1508                 goto discard;
1509 #endif
1510
1511         if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1512                 TCP_CHECK_TIMER(sk);
1513                 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1514                         rsk = sk;
1515                         goto reset;
1516                 }
1517                 TCP_CHECK_TIMER(sk);
1518                 return 0;
1519         }
1520
1521         if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1522                 goto csum_err;
1523
1524         if (sk->sk_state == TCP_LISTEN) {
1525                 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1526                 if (!nsk)
1527                         goto discard;
1528
1529                 if (nsk != sk) {
1530                         if (tcp_child_process(sk, nsk, skb)) {
1531                                 rsk = nsk;
1532                                 goto reset;
1533                         }
1534                         return 0;
1535                 }
1536         }
1537
1538         TCP_CHECK_TIMER(sk);
1539         if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1540                 rsk = sk;
1541                 goto reset;
1542         }
1543         TCP_CHECK_TIMER(sk);
1544         return 0;
1545
1546 reset:
1547         tcp_v4_send_reset(rsk, skb);
1548 discard:
1549         kfree_skb(skb);
1550         /* Be careful here. If this function gets more complicated and
1551          * gcc suffers from register pressure on the x86, sk (in %ebx)
1552          * might be destroyed here. This current version compiles correctly,
1553          * but you have been warned.
1554          */
1555         return 0;
1556
1557 csum_err:
1558         TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1559         goto discard;
1560 }
1561
1562 /*
1563  *      From tcp_input.c
1564  */
1565
1566 int tcp_v4_rcv(struct sk_buff *skb)
1567 {
1568         const struct iphdr *iph;
1569         struct tcphdr *th;
1570         struct sock *sk;
1571         int ret;
1572         struct net *net = dev_net(skb->dev);
1573
1574         if (skb->pkt_type != PACKET_HOST)
1575                 goto discard_it;
1576
1577         /* Count it even if it's bad */
1578         TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1579
1580         if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1581                 goto discard_it;
1582
1583         th = tcp_hdr(skb);
1584
1585         if (th->doff < sizeof(struct tcphdr) / 4)
1586                 goto bad_packet;
1587         if (!pskb_may_pull(skb, th->doff * 4))
1588                 goto discard_it;
1589
1590         /* An explanation is required here, I think.
1591          * Packet length and doff are validated by header prediction,
1592          * provided case of th->doff==0 is eliminated.
1593          * So, we defer the checks. */
1594         if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1595                 goto bad_packet;
1596
1597         th = tcp_hdr(skb);
1598         iph = ip_hdr(skb);
1599         TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1600         TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1601                                     skb->len - th->doff * 4);
1602         TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1603         TCP_SKB_CB(skb)->when    = 0;
1604         TCP_SKB_CB(skb)->flags   = iph->tos;
1605         TCP_SKB_CB(skb)->sacked  = 0;
1606
1607         sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1608         if (!sk)
1609                 goto no_tcp_socket;
1610
1611 process:
1612         if (sk->sk_state == TCP_TIME_WAIT)
1613                 goto do_time_wait;
1614
1615         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1616                 goto discard_and_relse;
1617         nf_reset(skb);
1618
1619         if (sk_filter(sk, skb))
1620                 goto discard_and_relse;
1621
1622         skb->dev = NULL;
1623
1624         bh_lock_sock_nested(sk);
1625         ret = 0;
1626         if (!sock_owned_by_user(sk)) {
1627 #ifdef CONFIG_NET_DMA
1628                 struct tcp_sock *tp = tcp_sk(sk);
1629                 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1630                         tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1631                 if (tp->ucopy.dma_chan)
1632                         ret = tcp_v4_do_rcv(sk, skb);
1633                 else
1634 #endif
1635                 {
1636                         if (!tcp_prequeue(sk, skb))
1637                                 ret = tcp_v4_do_rcv(sk, skb);
1638                 }
1639         } else
1640                 sk_add_backlog(sk, skb);
1641         bh_unlock_sock(sk);
1642
1643         sock_put(sk);
1644
1645         return ret;
1646
1647 no_tcp_socket:
1648         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1649                 goto discard_it;
1650
1651         if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1652 bad_packet:
1653                 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1654         } else {
1655                 tcp_v4_send_reset(NULL, skb);
1656         }
1657
1658 discard_it:
1659         /* Discard frame. */
1660         kfree_skb(skb);
1661         return 0;
1662
1663 discard_and_relse:
1664         sock_put(sk);
1665         goto discard_it;
1666
1667 do_time_wait:
1668         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1669                 inet_twsk_put(inet_twsk(sk));
1670                 goto discard_it;
1671         }
1672
1673         if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1674                 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1675                 inet_twsk_put(inet_twsk(sk));
1676                 goto discard_it;
1677         }
1678         switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1679         case TCP_TW_SYN: {
1680                 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1681                                                         &tcp_hashinfo,
1682                                                         iph->daddr, th->dest,
1683                                                         inet_iif(skb));
1684                 if (sk2) {
1685                         inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1686                         inet_twsk_put(inet_twsk(sk));
1687                         sk = sk2;
1688                         goto process;
1689                 }
1690                 /* Fall through to ACK */
1691         }
1692         case TCP_TW_ACK:
1693                 tcp_v4_timewait_ack(sk, skb);
1694                 break;
1695         case TCP_TW_RST:
1696                 goto no_tcp_socket;
1697         case TCP_TW_SUCCESS:;
1698         }
1699         goto discard_it;
1700 }
1701
1702 /* VJ's idea. Save last timestamp seen from this destination
1703  * and hold it at least for normal timewait interval to use for duplicate
1704  * segment detection in subsequent connections, before they enter synchronized
1705  * state.
1706  */
1707
1708 int tcp_v4_remember_stamp(struct sock *sk)
1709 {
1710         struct inet_sock *inet = inet_sk(sk);
1711         struct tcp_sock *tp = tcp_sk(sk);
1712         struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1713         struct inet_peer *peer = NULL;
1714         int release_it = 0;
1715
1716         if (!rt || rt->rt_dst != inet->inet_daddr) {
1717                 peer = inet_getpeer(inet->inet_daddr, 1);
1718                 release_it = 1;
1719         } else {
1720                 if (!rt->peer)
1721                         rt_bind_peer(rt, 1);
1722                 peer = rt->peer;
1723         }
1724
1725         if (peer) {
1726                 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1727                     (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1728                      peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1729                         peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1730                         peer->tcp_ts = tp->rx_opt.ts_recent;
1731                 }
1732                 if (release_it)
1733                         inet_putpeer(peer);
1734                 return 1;
1735         }
1736
1737         return 0;
1738 }
1739
1740 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1741 {
1742         struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1743
1744         if (peer) {
1745                 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1746
1747                 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1748                     (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1749                      peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1750                         peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1751                         peer->tcp_ts       = tcptw->tw_ts_recent;
1752                 }
1753                 inet_putpeer(peer);
1754                 return 1;
1755         }
1756
1757         return 0;
1758 }
1759
1760 const struct inet_connection_sock_af_ops ipv4_specific = {
1761         .queue_xmit        = ip_queue_xmit,
1762         .send_check        = tcp_v4_send_check,
1763         .rebuild_header    = inet_sk_rebuild_header,
1764         .conn_request      = tcp_v4_conn_request,
1765         .syn_recv_sock     = tcp_v4_syn_recv_sock,
1766         .remember_stamp    = tcp_v4_remember_stamp,
1767         .net_header_len    = sizeof(struct iphdr),
1768         .setsockopt        = ip_setsockopt,
1769         .getsockopt        = ip_getsockopt,
1770         .addr2sockaddr     = inet_csk_addr2sockaddr,
1771         .sockaddr_len      = sizeof(struct sockaddr_in),
1772         .bind_conflict     = inet_csk_bind_conflict,
1773 #ifdef CONFIG_COMPAT
1774         .compat_setsockopt = compat_ip_setsockopt,
1775         .compat_getsockopt = compat_ip_getsockopt,
1776 #endif
1777 };
1778
1779 #ifdef CONFIG_TCP_MD5SIG
1780 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1781         .md5_lookup             = tcp_v4_md5_lookup,
1782         .calc_md5_hash          = tcp_v4_md5_hash_skb,
1783         .md5_add                = tcp_v4_md5_add_func,
1784         .md5_parse              = tcp_v4_parse_md5_keys,
1785 };
1786 #endif
1787
1788 /* NOTE: A lot of things set to zero explicitly by call to
1789  *       sk_alloc() so need not be done here.
1790  */
1791 static int tcp_v4_init_sock(struct sock *sk)
1792 {
1793         struct inet_connection_sock *icsk = inet_csk(sk);
1794         struct tcp_sock *tp = tcp_sk(sk);
1795
1796         skb_queue_head_init(&tp->out_of_order_queue);
1797         tcp_init_xmit_timers(sk);
1798         tcp_prequeue_init(tp);
1799
1800         icsk->icsk_rto = TCP_TIMEOUT_INIT;
1801         tp->mdev = TCP_TIMEOUT_INIT;
1802
1803         /* So many TCP implementations out there (incorrectly) count the
1804          * initial SYN frame in their delayed-ACK and congestion control
1805          * algorithms that we must have the following bandaid to talk
1806          * efficiently to them.  -DaveM
1807          */
1808         tp->snd_cwnd = 2;
1809
1810         /* See draft-stevens-tcpca-spec-01 for discussion of the
1811          * initialization of these values.
1812          */
1813         tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
1814         tp->snd_cwnd_clamp = ~0;
1815         tp->mss_cache = 536;
1816
1817         tp->reordering = sysctl_tcp_reordering;
1818         icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1819
1820         sk->sk_state = TCP_CLOSE;
1821
1822         sk->sk_write_space = sk_stream_write_space;
1823         sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1824
1825         icsk->icsk_af_ops = &ipv4_specific;
1826         icsk->icsk_sync_mss = tcp_sync_mss;
1827 #ifdef CONFIG_TCP_MD5SIG
1828         tp->af_specific = &tcp_sock_ipv4_specific;
1829 #endif
1830
1831         sk->sk_sndbuf = sysctl_tcp_wmem[1];
1832         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1833
1834         local_bh_disable();
1835         percpu_counter_inc(&tcp_sockets_allocated);
1836         local_bh_enable();
1837
1838         return 0;
1839 }
1840
1841 void tcp_v4_destroy_sock(struct sock *sk)
1842 {
1843         struct tcp_sock *tp = tcp_sk(sk);
1844
1845         tcp_clear_xmit_timers(sk);
1846
1847         tcp_cleanup_congestion_control(sk);
1848
1849         /* Cleanup up the write buffer. */
1850         tcp_write_queue_purge(sk);
1851
1852         /* Cleans up our, hopefully empty, out_of_order_queue. */
1853         __skb_queue_purge(&tp->out_of_order_queue);
1854
1855 #ifdef CONFIG_TCP_MD5SIG
1856         /* Clean up the MD5 key list, if any */
1857         if (tp->md5sig_info) {
1858                 tcp_v4_clear_md5_list(sk);
1859                 kfree(tp->md5sig_info);
1860                 tp->md5sig_info = NULL;
1861         }
1862 #endif
1863
1864 #ifdef CONFIG_NET_DMA
1865         /* Cleans up our sk_async_wait_queue */
1866         __skb_queue_purge(&sk->sk_async_wait_queue);
1867 #endif
1868
1869         /* Clean prequeue, it must be empty really */
1870         __skb_queue_purge(&tp->ucopy.prequeue);
1871
1872         /* Clean up a referenced TCP bind bucket. */
1873         if (inet_csk(sk)->icsk_bind_hash)
1874                 inet_put_port(sk);
1875
1876         /*
1877          * If sendmsg cached page exists, toss it.
1878          */
1879         if (sk->sk_sndmsg_page) {
1880                 __free_page(sk->sk_sndmsg_page);
1881                 sk->sk_sndmsg_page = NULL;
1882         }
1883
1884         percpu_counter_dec(&tcp_sockets_allocated);
1885 }
1886
1887 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1888
1889 #ifdef CONFIG_PROC_FS
1890 /* Proc filesystem TCP sock list dumping. */
1891
1892 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
1893 {
1894         return hlist_nulls_empty(head) ? NULL :
1895                 list_entry(head->first, struct inet_timewait_sock, tw_node);
1896 }
1897
1898 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1899 {
1900         return !is_a_nulls(tw->tw_node.next) ?
1901                 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1902 }
1903
1904 static void *listening_get_next(struct seq_file *seq, void *cur)
1905 {
1906         struct inet_connection_sock *icsk;
1907         struct hlist_nulls_node *node;
1908         struct sock *sk = cur;
1909         struct inet_listen_hashbucket *ilb;
1910         struct tcp_iter_state *st = seq->private;
1911         struct net *net = seq_file_net(seq);
1912
1913         if (!sk) {
1914                 st->bucket = 0;
1915                 ilb = &tcp_hashinfo.listening_hash[0];
1916                 spin_lock_bh(&ilb->lock);
1917                 sk = sk_nulls_head(&ilb->head);
1918                 goto get_sk;
1919         }
1920         ilb = &tcp_hashinfo.listening_hash[st->bucket];
1921         ++st->num;
1922
1923         if (st->state == TCP_SEQ_STATE_OPENREQ) {
1924                 struct request_sock *req = cur;
1925
1926                 icsk = inet_csk(st->syn_wait_sk);
1927                 req = req->dl_next;
1928                 while (1) {
1929                         while (req) {
1930                                 if (req->rsk_ops->family == st->family) {
1931                                         cur = req;
1932                                         goto out;
1933                                 }
1934                                 req = req->dl_next;
1935                         }
1936                         if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1937                                 break;
1938 get_req:
1939                         req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1940                 }
1941                 sk        = sk_next(st->syn_wait_sk);
1942                 st->state = TCP_SEQ_STATE_LISTENING;
1943                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1944         } else {
1945                 icsk = inet_csk(sk);
1946                 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1947                 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1948                         goto start_req;
1949                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1950                 sk = sk_next(sk);
1951         }
1952 get_sk:
1953         sk_nulls_for_each_from(sk, node) {
1954                 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
1955                         cur = sk;
1956                         goto out;
1957                 }
1958                 icsk = inet_csk(sk);
1959                 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1960                 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1961 start_req:
1962                         st->uid         = sock_i_uid(sk);
1963                         st->syn_wait_sk = sk;
1964                         st->state       = TCP_SEQ_STATE_OPENREQ;
1965                         st->sbucket     = 0;
1966                         goto get_req;
1967                 }
1968                 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1969         }
1970         spin_unlock_bh(&ilb->lock);
1971         if (++st->bucket < INET_LHTABLE_SIZE) {
1972                 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1973                 spin_lock_bh(&ilb->lock);
1974                 sk = sk_nulls_head(&ilb->head);
1975                 goto get_sk;
1976         }
1977         cur = NULL;
1978 out:
1979         return cur;
1980 }
1981
1982 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1983 {
1984         void *rc = listening_get_next(seq, NULL);
1985
1986         while (rc && *pos) {
1987                 rc = listening_get_next(seq, rc);
1988                 --*pos;
1989         }
1990         return rc;
1991 }
1992
1993 static inline int empty_bucket(struct tcp_iter_state *st)
1994 {
1995         return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
1996                 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
1997 }
1998
1999 static void *established_get_first(struct seq_file *seq)
2000 {
2001         struct tcp_iter_state *st = seq->private;
2002         struct net *net = seq_file_net(seq);
2003         void *rc = NULL;
2004
2005         for (st->bucket = 0; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
2006                 struct sock *sk;
2007                 struct hlist_nulls_node *node;
2008                 struct inet_timewait_sock *tw;
2009                 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
2010
2011                 /* Lockless fast path for the common case of empty buckets */
2012                 if (empty_bucket(st))
2013                         continue;
2014
2015                 spin_lock_bh(lock);
2016                 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2017                         if (sk->sk_family != st->family ||
2018                             !net_eq(sock_net(sk), net)) {
2019                                 continue;
2020                         }
2021                         rc = sk;
2022                         goto out;
2023                 }
2024                 st->state = TCP_SEQ_STATE_TIME_WAIT;
2025                 inet_twsk_for_each(tw, node,
2026                                    &tcp_hashinfo.ehash[st->bucket].twchain) {
2027                         if (tw->tw_family != st->family ||
2028                             !net_eq(twsk_net(tw), net)) {
2029                                 continue;
2030                         }
2031                         rc = tw;
2032                         goto out;
2033                 }
2034                 spin_unlock_bh(lock);
2035                 st->state = TCP_SEQ_STATE_ESTABLISHED;
2036         }
2037 out:
2038         return rc;
2039 }
2040
2041 static void *established_get_next(struct seq_file *seq, void *cur)
2042 {
2043         struct sock *sk = cur;
2044         struct inet_timewait_sock *tw;
2045         struct hlist_nulls_node *node;
2046         struct tcp_iter_state *st = seq->private;
2047         struct net *net = seq_file_net(seq);
2048
2049         ++st->num;
2050
2051         if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2052                 tw = cur;
2053                 tw = tw_next(tw);
2054 get_tw:
2055                 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2056                         tw = tw_next(tw);
2057                 }
2058                 if (tw) {
2059                         cur = tw;
2060                         goto out;
2061                 }
2062                 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2063                 st->state = TCP_SEQ_STATE_ESTABLISHED;
2064
2065                 /* Look for next non empty bucket */
2066                 while (++st->bucket <= tcp_hashinfo.ehash_mask &&
2067                                 empty_bucket(st))
2068                         ;
2069                 if (st->bucket > tcp_hashinfo.ehash_mask)
2070                         return NULL;
2071
2072                 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2073                 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2074         } else
2075                 sk = sk_nulls_next(sk);
2076
2077         sk_nulls_for_each_from(sk, node) {
2078                 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2079                         goto found;
2080         }
2081
2082         st->state = TCP_SEQ_STATE_TIME_WAIT;
2083         tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2084         goto get_tw;
2085 found:
2086         cur = sk;
2087 out:
2088         return cur;
2089 }
2090
2091 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2092 {
2093         void *rc = established_get_first(seq);
2094
2095         while (rc && pos) {
2096                 rc = established_get_next(seq, rc);
2097                 --pos;
2098         }
2099         return rc;
2100 }
2101
2102 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2103 {
2104         void *rc;
2105         struct tcp_iter_state *st = seq->private;
2106
2107         st->state = TCP_SEQ_STATE_LISTENING;
2108         rc        = listening_get_idx(seq, &pos);
2109
2110         if (!rc) {
2111                 st->state = TCP_SEQ_STATE_ESTABLISHED;
2112                 rc        = established_get_idx(seq, pos);
2113         }
2114
2115         return rc;
2116 }
2117
2118 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2119 {
2120         struct tcp_iter_state *st = seq->private;
2121         st->state = TCP_SEQ_STATE_LISTENING;
2122         st->num = 0;
2123         return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2124 }
2125
2126 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2127 {
2128         void *rc = NULL;
2129         struct tcp_iter_state *st;
2130
2131         if (v == SEQ_START_TOKEN) {
2132                 rc = tcp_get_idx(seq, 0);
2133                 goto out;
2134         }
2135         st = seq->private;
2136
2137         switch (st->state) {
2138         case TCP_SEQ_STATE_OPENREQ:
2139         case TCP_SEQ_STATE_LISTENING:
2140                 rc = listening_get_next(seq, v);
2141                 if (!rc) {
2142                         st->state = TCP_SEQ_STATE_ESTABLISHED;
2143                         rc        = established_get_first(seq);
2144                 }
2145                 break;
2146         case TCP_SEQ_STATE_ESTABLISHED:
2147         case TCP_SEQ_STATE_TIME_WAIT:
2148                 rc = established_get_next(seq, v);
2149                 break;
2150         }
2151 out:
2152         ++*pos;
2153         return rc;
2154 }
2155
2156 static void tcp_seq_stop(struct seq_file *seq, void *v)
2157 {
2158         struct tcp_iter_state *st = seq->private;
2159
2160         switch (st->state) {
2161         case TCP_SEQ_STATE_OPENREQ:
2162                 if (v) {
2163                         struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2164                         read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2165                 }
2166         case TCP_SEQ_STATE_LISTENING:
2167                 if (v != SEQ_START_TOKEN)
2168                         spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2169                 break;
2170         case TCP_SEQ_STATE_TIME_WAIT:
2171         case TCP_SEQ_STATE_ESTABLISHED:
2172                 if (v)
2173                         spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2174                 break;
2175         }
2176 }
2177
2178 static int tcp_seq_open(struct inode *inode, struct file *file)
2179 {
2180         struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2181         struct tcp_iter_state *s;
2182         int err;
2183
2184         err = seq_open_net(inode, file, &afinfo->seq_ops,
2185                           sizeof(struct tcp_iter_state));
2186         if (err < 0)
2187                 return err;
2188
2189         s = ((struct seq_file *)file->private_data)->private;
2190         s->family               = afinfo->family;
2191         return 0;
2192 }
2193
2194 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2195 {
2196         int rc = 0;
2197         struct proc_dir_entry *p;
2198
2199         afinfo->seq_fops.open           = tcp_seq_open;
2200         afinfo->seq_fops.read           = seq_read;
2201         afinfo->seq_fops.llseek         = seq_lseek;
2202         afinfo->seq_fops.release        = seq_release_net;
2203
2204         afinfo->seq_ops.start           = tcp_seq_start;
2205         afinfo->seq_ops.next            = tcp_seq_next;
2206         afinfo->seq_ops.stop            = tcp_seq_stop;
2207
2208         p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2209                              &afinfo->seq_fops, afinfo);
2210         if (!p)
2211                 rc = -ENOMEM;
2212         return rc;
2213 }
2214
2215 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2216 {
2217         proc_net_remove(net, afinfo->name);
2218 }
2219
2220 static void get_openreq4(struct sock *sk, struct request_sock *req,
2221                          struct seq_file *f, int i, int uid, int *len)
2222 {
2223         const struct inet_request_sock *ireq = inet_rsk(req);
2224         int ttd = req->expires - jiffies;
2225
2226         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2227                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
2228                 i,
2229                 ireq->loc_addr,
2230                 ntohs(inet_sk(sk)->inet_sport),
2231                 ireq->rmt_addr,
2232                 ntohs(ireq->rmt_port),
2233                 TCP_SYN_RECV,
2234                 0, 0, /* could print option size, but that is af dependent. */
2235                 1,    /* timers active (only the expire timer) */
2236                 jiffies_to_clock_t(ttd),
2237                 req->retrans,
2238                 uid,
2239                 0,  /* non standard timer */
2240                 0, /* open_requests have no inode */
2241                 atomic_read(&sk->sk_refcnt),
2242                 req,
2243                 len);
2244 }
2245
2246 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2247 {
2248         int timer_active;
2249         unsigned long timer_expires;
2250         struct tcp_sock *tp = tcp_sk(sk);
2251         const struct inet_connection_sock *icsk = inet_csk(sk);
2252         struct inet_sock *inet = inet_sk(sk);
2253         __be32 dest = inet->inet_daddr;
2254         __be32 src = inet->inet_rcv_saddr;
2255         __u16 destp = ntohs(inet->inet_dport);
2256         __u16 srcp = ntohs(inet->inet_sport);
2257
2258         if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2259                 timer_active    = 1;
2260                 timer_expires   = icsk->icsk_timeout;
2261         } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2262                 timer_active    = 4;
2263                 timer_expires   = icsk->icsk_timeout;
2264         } else if (timer_pending(&sk->sk_timer)) {
2265                 timer_active    = 2;
2266                 timer_expires   = sk->sk_timer.expires;
2267         } else {
2268                 timer_active    = 0;
2269                 timer_expires = jiffies;
2270         }
2271
2272         seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2273                         "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2274                 i, src, srcp, dest, destp, sk->sk_state,
2275                 tp->write_seq - tp->snd_una,
2276                 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2277                                              (tp->rcv_nxt - tp->copied_seq),
2278                 timer_active,
2279                 jiffies_to_clock_t(timer_expires - jiffies),
2280                 icsk->icsk_retransmits,
2281                 sock_i_uid(sk),
2282                 icsk->icsk_probes_out,
2283                 sock_i_ino(sk),
2284                 atomic_read(&sk->sk_refcnt), sk,
2285                 jiffies_to_clock_t(icsk->icsk_rto),
2286                 jiffies_to_clock_t(icsk->icsk_ack.ato),
2287                 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2288                 tp->snd_cwnd,
2289                 tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh,
2290                 len);
2291 }
2292
2293 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2294                                struct seq_file *f, int i, int *len)
2295 {
2296         __be32 dest, src;
2297         __u16 destp, srcp;
2298         int ttd = tw->tw_ttd - jiffies;
2299
2300         if (ttd < 0)
2301                 ttd = 0;
2302
2303         dest  = tw->tw_daddr;
2304         src   = tw->tw_rcv_saddr;
2305         destp = ntohs(tw->tw_dport);
2306         srcp  = ntohs(tw->tw_sport);
2307
2308         seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2309                 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
2310                 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2311                 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2312                 atomic_read(&tw->tw_refcnt), tw, len);
2313 }
2314
2315 #define TMPSZ 150
2316
2317 static int tcp4_seq_show(struct seq_file *seq, void *v)
2318 {
2319         struct tcp_iter_state *st;
2320         int len;
2321
2322         if (v == SEQ_START_TOKEN) {
2323                 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2324                            "  sl  local_address rem_address   st tx_queue "
2325                            "rx_queue tr tm->when retrnsmt   uid  timeout "
2326                            "inode");
2327                 goto out;
2328         }
2329         st = seq->private;
2330
2331         switch (st->state) {
2332         case TCP_SEQ_STATE_LISTENING:
2333         case TCP_SEQ_STATE_ESTABLISHED:
2334                 get_tcp4_sock(v, seq, st->num, &len);
2335                 break;
2336         case TCP_SEQ_STATE_OPENREQ:
2337                 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2338                 break;
2339         case TCP_SEQ_STATE_TIME_WAIT:
2340                 get_timewait4_sock(v, seq, st->num, &len);
2341                 break;
2342         }
2343         seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2344 out:
2345         return 0;
2346 }
2347
2348 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2349         .name           = "tcp",
2350         .family         = AF_INET,
2351         .seq_fops       = {
2352                 .owner          = THIS_MODULE,
2353         },
2354         .seq_ops        = {
2355                 .show           = tcp4_seq_show,
2356         },
2357 };
2358
2359 static int tcp4_proc_init_net(struct net *net)
2360 {
2361         return tcp_proc_register(net, &tcp4_seq_afinfo);
2362 }
2363
2364 static void tcp4_proc_exit_net(struct net *net)
2365 {
2366         tcp_proc_unregister(net, &tcp4_seq_afinfo);
2367 }
2368
2369 static struct pernet_operations tcp4_net_ops = {
2370         .init = tcp4_proc_init_net,
2371         .exit = tcp4_proc_exit_net,
2372 };
2373
2374 int __init tcp4_proc_init(void)
2375 {
2376         return register_pernet_subsys(&tcp4_net_ops);
2377 }
2378
2379 void tcp4_proc_exit(void)
2380 {
2381         unregister_pernet_subsys(&tcp4_net_ops);
2382 }
2383 #endif /* CONFIG_PROC_FS */
2384
2385 struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2386 {
2387         struct iphdr *iph = skb_gro_network_header(skb);
2388
2389         switch (skb->ip_summed) {
2390         case CHECKSUM_COMPLETE:
2391                 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
2392                                   skb->csum)) {
2393                         skb->ip_summed = CHECKSUM_UNNECESSARY;
2394                         break;
2395                 }
2396
2397                 /* fall through */
2398         case CHECKSUM_NONE:
2399                 NAPI_GRO_CB(skb)->flush = 1;
2400                 return NULL;
2401         }
2402
2403         return tcp_gro_receive(head, skb);
2404 }
2405 EXPORT_SYMBOL(tcp4_gro_receive);
2406
2407 int tcp4_gro_complete(struct sk_buff *skb)
2408 {
2409         struct iphdr *iph = ip_hdr(skb);
2410         struct tcphdr *th = tcp_hdr(skb);
2411
2412         th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
2413                                   iph->saddr, iph->daddr, 0);
2414         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
2415
2416         return tcp_gro_complete(skb);
2417 }
2418 EXPORT_SYMBOL(tcp4_gro_complete);
2419
2420 struct proto tcp_prot = {
2421         .name                   = "TCP",
2422         .owner                  = THIS_MODULE,
2423         .close                  = tcp_close,
2424         .connect                = tcp_v4_connect,
2425         .disconnect             = tcp_disconnect,
2426         .accept                 = inet_csk_accept,
2427         .ioctl                  = tcp_ioctl,
2428         .init                   = tcp_v4_init_sock,
2429         .destroy                = tcp_v4_destroy_sock,
2430         .shutdown               = tcp_shutdown,
2431         .setsockopt             = tcp_setsockopt,
2432         .getsockopt             = tcp_getsockopt,
2433         .recvmsg                = tcp_recvmsg,
2434         .backlog_rcv            = tcp_v4_do_rcv,
2435         .hash                   = inet_hash,
2436         .unhash                 = inet_unhash,
2437         .get_port               = inet_csk_get_port,
2438         .enter_memory_pressure  = tcp_enter_memory_pressure,
2439         .sockets_allocated      = &tcp_sockets_allocated,
2440         .orphan_count           = &tcp_orphan_count,
2441         .memory_allocated       = &tcp_memory_allocated,
2442         .memory_pressure        = &tcp_memory_pressure,
2443         .sysctl_mem             = sysctl_tcp_mem,
2444         .sysctl_wmem            = sysctl_tcp_wmem,
2445         .sysctl_rmem            = sysctl_tcp_rmem,
2446         .max_header             = MAX_TCP_HEADER,
2447         .obj_size               = sizeof(struct tcp_sock),
2448         .slab_flags             = SLAB_DESTROY_BY_RCU,
2449         .twsk_prot              = &tcp_timewait_sock_ops,
2450         .rsk_prot               = &tcp_request_sock_ops,
2451         .h.hashinfo             = &tcp_hashinfo,
2452 #ifdef CONFIG_COMPAT
2453         .compat_setsockopt      = compat_tcp_setsockopt,
2454         .compat_getsockopt      = compat_tcp_getsockopt,
2455 #endif
2456 };
2457
2458
2459 static int __net_init tcp_sk_init(struct net *net)
2460 {
2461         return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2462                                     PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2463 }
2464
2465 static void __net_exit tcp_sk_exit(struct net *net)
2466 {
2467         inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2468         inet_twsk_purge(net, &tcp_hashinfo, &tcp_death_row, AF_INET);
2469 }
2470
2471 static struct pernet_operations __net_initdata tcp_sk_ops = {
2472        .init = tcp_sk_init,
2473        .exit = tcp_sk_exit,
2474 };
2475
2476 void __init tcp_v4_init(void)
2477 {
2478         inet_hashinfo_init(&tcp_hashinfo);
2479         if (register_pernet_subsys(&tcp_sk_ops))
2480                 panic("Failed to create the TCP control socket.\n");
2481 }
2482
2483 EXPORT_SYMBOL(ipv4_specific);
2484 EXPORT_SYMBOL(tcp_hashinfo);
2485 EXPORT_SYMBOL(tcp_prot);
2486 EXPORT_SYMBOL(tcp_v4_conn_request);
2487 EXPORT_SYMBOL(tcp_v4_connect);
2488 EXPORT_SYMBOL(tcp_v4_do_rcv);
2489 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2490 EXPORT_SYMBOL(tcp_v4_send_check);
2491 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2492
2493 #ifdef CONFIG_PROC_FS
2494 EXPORT_SYMBOL(tcp_proc_register);
2495 EXPORT_SYMBOL(tcp_proc_unregister);
2496 #endif
2497 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2498