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Linux 2.6.19-rc6
[cris-mirror.git] / net / ipv4 / tcp_ipv4.c
blob22ef8bd26620ab122d56ef2220ef2f43e9ab4442
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 * Version: $Id: tcp_ipv4.c,v 1.240 2002/02/01 22:01:04 davem Exp $
9 *
10 * IPv4 specific functions
11 *
12 *
13 * code split from:
14 * linux/ipv4/tcp.c
15 * linux/ipv4/tcp_input.c
16 * linux/ipv4/tcp_output.c
17 *
18 * See tcp.c for author information
19 *
20 * This program is free software; you can redistribute it and/or
21 * modify it under the terms of the GNU General Public License
22 * as published by the Free Software Foundation; either version
23 * 2 of the License, or (at your option) any later version.
24 */
25
26 /*
27 * Changes:
28 * David S. Miller : New socket lookup architecture.
29 * This code is dedicated to John Dyson.
30 * David S. Miller : Change semantics of established hash,
31 * half is devoted to TIME_WAIT sockets
32 * and the rest go in the other half.
33 * Andi Kleen : Add support for syncookies and fixed
34 * some bugs: ip options weren't passed to
35 * the TCP layer, missed a check for an
36 * ACK bit.
37 * Andi Kleen : Implemented fast path mtu discovery.
38 * Fixed many serious bugs in the
39 * request_sock handling and moved
40 * most of it into the af independent code.
41 * Added tail drop and some other bugfixes.
42 * Added new listen semantics.
43 * Mike McLagan : Routing by source
44 * Juan Jose Ciarlante: ip_dynaddr bits
45 * Andi Kleen: various fixes.
46 * Vitaly E. Lavrov : Transparent proxy revived after year
47 * coma.
48 * Andi Kleen : Fix new listen.
49 * Andi Kleen : Fix accept error reporting.
50 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which
51 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind
52 * a single port at the same time.
53 */
54
55
56 #include <linux/types.h>
57 #include <linux/fcntl.h>
58 #include <linux/module.h>
59 #include <linux/random.h>
60 #include <linux/cache.h>
61 #include <linux/jhash.h>
62 #include <linux/init.h>
63 #include <linux/times.h>
64
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 int sysctl_tcp_tw_reuse __read_mostly;
82 int sysctl_tcp_low_latency __read_mostly;
83
84 /* Check TCP sequence numbers in ICMP packets. */
85 #define ICMP_MIN_LENGTH 8
86
87 /* Socket used for sending RSTs */
88 static struct socket *tcp_socket;
89
90 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
91
92 struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
93 .lhash_lock = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
94 .lhash_users = ATOMIC_INIT(0),
95 .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
96 };
97
98 static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
99 {
100 return inet_csk_get_port(&tcp_hashinfo, sk, snum,
101 inet_csk_bind_conflict);
102 }
103
104 static void tcp_v4_hash(struct sock *sk)
105 {
106 inet_hash(&tcp_hashinfo, sk);
107 }
108
109 void tcp_unhash(struct sock *sk)
110 {
111 inet_unhash(&tcp_hashinfo, sk);
112 }
113
114 static inline __u32 tcp_v4_init_sequence(struct sock *sk, struct sk_buff *skb)
115 {
116 return secure_tcp_sequence_number(skb->nh.iph->daddr,
117 skb->nh.iph->saddr,
118 skb->h.th->dest,
119 skb->h.th->source);
120 }
121
122 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
123 {
124 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
125 struct tcp_sock *tp = tcp_sk(sk);
126
127 /* With PAWS, it is safe from the viewpoint
128 of data integrity. Even without PAWS it is safe provided sequence
129 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
130
131 Actually, the idea is close to VJ's one, only timestamp cache is
132 held not per host, but per port pair and TW bucket is used as state
133 holder.
134
135 If TW bucket has been already destroyed we fall back to VJ's scheme
136 and use initial timestamp retrieved from peer table.
137 */
138 if (tcptw->tw_ts_recent_stamp &&
139 (twp == NULL || (sysctl_tcp_tw_reuse &&
140 xtime.tv_sec - tcptw->tw_ts_recent_stamp > 1))) {
141 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
142 if (tp->write_seq == 0)
143 tp->write_seq = 1;
144 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
145 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
146 sock_hold(sktw);
147 return 1;
148 }
149
150 return 0;
151 }
152
153 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
154
155 /* This will initiate an outgoing connection. */
156 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
157 {
158 struct inet_sock *inet = inet_sk(sk);
159 struct tcp_sock *tp = tcp_sk(sk);
160 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
161 struct rtable *rt;
162 __be32 daddr, nexthop;
163 int tmp;
164 int err;
165
166 if (addr_len < sizeof(struct sockaddr_in))
167 return -EINVAL;
168
169 if (usin->sin_family != AF_INET)
170 return -EAFNOSUPPORT;
171
172 nexthop = daddr = usin->sin_addr.s_addr;
173 if (inet->opt && inet->opt->srr) {
174 if (!daddr)
175 return -EINVAL;
176 nexthop = inet->opt->faddr;
177 }
178
179 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
180 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
181 IPPROTO_TCP,
182 inet->sport, usin->sin_port, sk);
183 if (tmp < 0)
184 return tmp;
185
186 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
187 ip_rt_put(rt);
188 return -ENETUNREACH;
189 }
190
191 if (!inet->opt || !inet->opt->srr)
192 daddr = rt->rt_dst;
193
194 if (!inet->saddr)
195 inet->saddr = rt->rt_src;
196 inet->rcv_saddr = inet->saddr;
197
198 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
199 /* Reset inherited state */
200 tp->rx_opt.ts_recent = 0;
201 tp->rx_opt.ts_recent_stamp = 0;
202 tp->write_seq = 0;
203 }
204
205 if (tcp_death_row.sysctl_tw_recycle &&
206 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
207 struct inet_peer *peer = rt_get_peer(rt);
208
209 /* VJ's idea. We save last timestamp seen from
210 * the destination in peer table, when entering state TIME-WAIT
211 * and initialize rx_opt.ts_recent from it, when trying new connection.
212 */
213
214 if (peer && peer->tcp_ts_stamp + TCP_PAWS_MSL >= xtime.tv_sec) {
215 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
216 tp->rx_opt.ts_recent = peer->tcp_ts;
217 }
218 }
219
220 inet->dport = usin->sin_port;
221 inet->daddr = daddr;
222
223 inet_csk(sk)->icsk_ext_hdr_len = 0;
224 if (inet->opt)
225 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
226
227 tp->rx_opt.mss_clamp = 536;
228
229 /* Socket identity is still unknown (sport may be zero).
230 * However we set state to SYN-SENT and not releasing socket
231 * lock select source port, enter ourselves into the hash tables and
232 * complete initialization after this.
233 */
234 tcp_set_state(sk, TCP_SYN_SENT);
235 err = inet_hash_connect(&tcp_death_row, sk);
236 if (err)
237 goto failure;
238
239 err = ip_route_newports(&rt, IPPROTO_TCP, inet->sport, inet->dport, sk);
240 if (err)
241 goto failure;
242
243 /* OK, now commit destination to socket. */
244 sk->sk_gso_type = SKB_GSO_TCPV4;
245 sk_setup_caps(sk, &rt->u.dst);
246
247 if (!tp->write_seq)
248 tp->write_seq = secure_tcp_sequence_number(inet->saddr,
249 inet->daddr,
250 inet->sport,
251 usin->sin_port);
252
253 inet->id = tp->write_seq ^ jiffies;
254
255 err = tcp_connect(sk);
256 rt = NULL;
257 if (err)
258 goto failure;
259
260 return 0;
261
262 failure:
263 /* This unhashes the socket and releases the local port, if necessary. */
264 tcp_set_state(sk, TCP_CLOSE);
265 ip_rt_put(rt);
266 sk->sk_route_caps = 0;
267 inet->dport = 0;
268 return err;
269 }
270
271 /*
272 * This routine does path mtu discovery as defined in RFC1191.
273 */
274 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu)
275 {
276 struct dst_entry *dst;
277 struct inet_sock *inet = inet_sk(sk);
278
279 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
280 * send out by Linux are always <576bytes so they should go through
281 * unfragmented).
282 */
283 if (sk->sk_state == TCP_LISTEN)
284 return;
285
286 /* We don't check in the destentry if pmtu discovery is forbidden
287 * on this route. We just assume that no packet_to_big packets
288 * are send back when pmtu discovery is not active.
289 * There is a small race when the user changes this flag in the
290 * route, but I think that's acceptable.
291 */
292 if ((dst = __sk_dst_check(sk, 0)) == NULL)
293 return;
294
295 dst->ops->update_pmtu(dst, mtu);
296
297 /* Something is about to be wrong... Remember soft error
298 * for the case, if this connection will not able to recover.
299 */
300 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
301 sk->sk_err_soft = EMSGSIZE;
302
303 mtu = dst_mtu(dst);
304
305 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
306 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
307 tcp_sync_mss(sk, mtu);
308
309 /* Resend the TCP packet because it's
310 * clear that the old packet has been
311 * dropped. This is the new "fast" path mtu
312 * discovery.
313 */
314 tcp_simple_retransmit(sk);
315 } /* else let the usual retransmit timer handle it */
316 }
317
318 /*
319 * This routine is called by the ICMP module when it gets some
320 * sort of error condition. If err < 0 then the socket should
321 * be closed and the error returned to the user. If err > 0
322 * it's just the icmp type << 8 | icmp code. After adjustment
323 * header points to the first 8 bytes of the tcp header. We need
324 * to find the appropriate port.
325 *
326 * The locking strategy used here is very "optimistic". When
327 * someone else accesses the socket the ICMP is just dropped
328 * and for some paths there is no check at all.
329 * A more general error queue to queue errors for later handling
330 * is probably better.
331 *
332 */
333
334 void tcp_v4_err(struct sk_buff *skb, u32 info)
335 {
336 struct iphdr *iph = (struct iphdr *)skb->data;
337 struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
338 struct tcp_sock *tp;
339 struct inet_sock *inet;
340 int type = skb->h.icmph->type;
341 int code = skb->h.icmph->code;
342 struct sock *sk;
343 __u32 seq;
344 int err;
345
346 if (skb->len < (iph->ihl << 2) + 8) {
347 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
348 return;
349 }
350
351 sk = inet_lookup(&tcp_hashinfo, iph->daddr, th->dest, iph->saddr,
352 th->source, inet_iif(skb));
353 if (!sk) {
354 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
355 return;
356 }
357 if (sk->sk_state == TCP_TIME_WAIT) {
358 inet_twsk_put(inet_twsk(sk));
359 return;
360 }
361
362 bh_lock_sock(sk);
363 /* If too many ICMPs get dropped on busy
364 * servers this needs to be solved differently.
365 */
366 if (sock_owned_by_user(sk))
367 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
368
369 if (sk->sk_state == TCP_CLOSE)
370 goto out;
371
372 tp = tcp_sk(sk);
373 seq = ntohl(th->seq);
374 if (sk->sk_state != TCP_LISTEN &&
375 !between(seq, tp->snd_una, tp->snd_nxt)) {
376 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
377 goto out;
378 }
379
380 switch (type) {
381 case ICMP_SOURCE_QUENCH:
382 /* Just silently ignore these. */
383 goto out;
384 case ICMP_PARAMETERPROB:
385 err = EPROTO;
386 break;
387 case ICMP_DEST_UNREACH:
388 if (code > NR_ICMP_UNREACH)
389 goto out;
390
391 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
392 if (!sock_owned_by_user(sk))
393 do_pmtu_discovery(sk, iph, info);
394 goto out;
395 }
396
397 err = icmp_err_convert[code].errno;
398 break;
399 case ICMP_TIME_EXCEEDED:
400 err = EHOSTUNREACH;
401 break;
402 default:
403 goto out;
404 }
405
406 switch (sk->sk_state) {
407 struct request_sock *req, **prev;
408 case TCP_LISTEN:
409 if (sock_owned_by_user(sk))
410 goto out;
411
412 req = inet_csk_search_req(sk, &prev, th->dest,
413 iph->daddr, iph->saddr);
414 if (!req)
415 goto out;
416
417 /* ICMPs are not backlogged, hence we cannot get
418 an established socket here.
419 */
420 BUG_TRAP(!req->sk);
421
422 if (seq != tcp_rsk(req)->snt_isn) {
423 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
424 goto out;
425 }
426
427 /*
428 * Still in SYN_RECV, just remove it silently.
429 * There is no good way to pass the error to the newly
430 * created socket, and POSIX does not want network
431 * errors returned from accept().
432 */
433 inet_csk_reqsk_queue_drop(sk, req, prev);
434 goto out;
435
436 case TCP_SYN_SENT:
437 case TCP_SYN_RECV: /* Cannot happen.
438 It can f.e. if SYNs crossed.
439 */
440 if (!sock_owned_by_user(sk)) {
441 sk->sk_err = err;
442
443 sk->sk_error_report(sk);
444
445 tcp_done(sk);
446 } else {
447 sk->sk_err_soft = err;
448 }
449 goto out;
450 }
451
452 /* If we've already connected we will keep trying
453 * until we time out, or the user gives up.
454 *
455 * rfc1122 4.2.3.9 allows to consider as hard errors
456 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
457 * but it is obsoleted by pmtu discovery).
458 *
459 * Note, that in modern internet, where routing is unreliable
460 * and in each dark corner broken firewalls sit, sending random
461 * errors ordered by their masters even this two messages finally lose
462 * their original sense (even Linux sends invalid PORT_UNREACHs)
463 *
464 * Now we are in compliance with RFCs.
465 * --ANK (980905)
466 */
467
468 inet = inet_sk(sk);
469 if (!sock_owned_by_user(sk) && inet->recverr) {
470 sk->sk_err = err;
471 sk->sk_error_report(sk);
472 } else { /* Only an error on timeout */
473 sk->sk_err_soft = err;
474 }
475
476 out:
477 bh_unlock_sock(sk);
478 sock_put(sk);
479 }
480
481 /* This routine computes an IPv4 TCP checksum. */
482 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
483 {
484 struct inet_sock *inet = inet_sk(sk);
485 struct tcphdr *th = skb->h.th;
486
487 if (skb->ip_summed == CHECKSUM_PARTIAL) {
488 th->check = ~tcp_v4_check(th, len, inet->saddr, inet->daddr, 0);
489 skb->csum = offsetof(struct tcphdr, check);
490 } else {
491 th->check = tcp_v4_check(th, len, inet->saddr, inet->daddr,
492 csum_partial((char *)th,
493 th->doff << 2,
494 skb->csum));
495 }
496 }
497
498 int tcp_v4_gso_send_check(struct sk_buff *skb)
499 {
500 struct iphdr *iph;
501 struct tcphdr *th;
502
503 if (!pskb_may_pull(skb, sizeof(*th)))
504 return -EINVAL;
505
506 iph = skb->nh.iph;
507 th = skb->h.th;
508
509 th->check = 0;
510 th->check = ~tcp_v4_check(th, skb->len, iph->saddr, iph->daddr, 0);
511 skb->csum = offsetof(struct tcphdr, check);
512 skb->ip_summed = CHECKSUM_PARTIAL;
513 return 0;
514 }
515
516 /*
517 * This routine will send an RST to the other tcp.
518 *
519 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
520 * for reset.
521 * Answer: if a packet caused RST, it is not for a socket
522 * existing in our system, if it is matched to a socket,
523 * it is just duplicate segment or bug in other side's TCP.
524 * So that we build reply only basing on parameters
525 * arrived with segment.
526 * Exception: precedence violation. We do not implement it in any case.
527 */
528
529 static void tcp_v4_send_reset(struct sk_buff *skb)
530 {
531 struct tcphdr *th = skb->h.th;
532 struct tcphdr rth;
533 struct ip_reply_arg arg;
534
535 /* Never send a reset in response to a reset. */
536 if (th->rst)
537 return;
538
539 if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL)
540 return;
541
542 /* Swap the send and the receive. */
543 memset(&rth, 0, sizeof(struct tcphdr));
544 rth.dest = th->source;
545 rth.source = th->dest;
546 rth.doff = sizeof(struct tcphdr) / 4;
547 rth.rst = 1;
548
549 if (th->ack) {
550 rth.seq = th->ack_seq;
551 } else {
552 rth.ack = 1;
553 rth.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
554 skb->len - (th->doff << 2));
555 }
556
557 memset(&arg, 0, sizeof arg);
558 arg.iov[0].iov_base = (unsigned char *)&rth;
559 arg.iov[0].iov_len = sizeof rth;
560 arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
561 skb->nh.iph->saddr, /*XXX*/
562 sizeof(struct tcphdr), IPPROTO_TCP, 0);
563 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
564
565 ip_send_reply(tcp_socket->sk, skb, &arg, sizeof rth);
566
567 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
568 TCP_INC_STATS_BH(TCP_MIB_OUTRSTS);
569 }
570
571 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
572 outside socket context is ugly, certainly. What can I do?
573 */
574
575 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
576 u32 win, u32 ts)
577 {
578 struct tcphdr *th = skb->h.th;
579 struct {
580 struct tcphdr th;
581 u32 tsopt[TCPOLEN_TSTAMP_ALIGNED >> 2];
582 } rep;
583 struct ip_reply_arg arg;
584
585 memset(&rep.th, 0, sizeof(struct tcphdr));
586 memset(&arg, 0, sizeof arg);
587
588 arg.iov[0].iov_base = (unsigned char *)&rep;
589 arg.iov[0].iov_len = sizeof(rep.th);
590 if (ts) {
591 rep.tsopt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
592 (TCPOPT_TIMESTAMP << 8) |
593 TCPOLEN_TIMESTAMP);
594 rep.tsopt[1] = htonl(tcp_time_stamp);
595 rep.tsopt[2] = htonl(ts);
596 arg.iov[0].iov_len = sizeof(rep);
597 }
598
599 /* Swap the send and the receive. */
600 rep.th.dest = th->source;
601 rep.th.source = th->dest;
602 rep.th.doff = arg.iov[0].iov_len / 4;
603 rep.th.seq = htonl(seq);
604 rep.th.ack_seq = htonl(ack);
605 rep.th.ack = 1;
606 rep.th.window = htons(win);
607
608 arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
609 skb->nh.iph->saddr, /*XXX*/
610 arg.iov[0].iov_len, IPPROTO_TCP, 0);
611 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
612
613 ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
614
615 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
616 }
617
618 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
619 {
620 struct inet_timewait_sock *tw = inet_twsk(sk);
621 const struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
622
623 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
624 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, tcptw->tw_ts_recent);
625
626 inet_twsk_put(tw);
627 }
628
629 static void tcp_v4_reqsk_send_ack(struct sk_buff *skb, struct request_sock *req)
630 {
631 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
632 req->ts_recent);
633 }
634
635 /*
636 * Send a SYN-ACK after having received an ACK.
637 * This still operates on a request_sock only, not on a big
638 * socket.
639 */
640 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
641 struct dst_entry *dst)
642 {
643 const struct inet_request_sock *ireq = inet_rsk(req);
644 int err = -1;
645 struct sk_buff * skb;
646
647 /* First, grab a route. */
648 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
649 goto out;
650
651 skb = tcp_make_synack(sk, dst, req);
652
653 if (skb) {
654 struct tcphdr *th = skb->h.th;
655
656 th->check = tcp_v4_check(th, skb->len,
657 ireq->loc_addr,
658 ireq->rmt_addr,
659 csum_partial((char *)th, skb->len,
660 skb->csum));
661
662 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
663 ireq->rmt_addr,
664 ireq->opt);
665 if (err == NET_XMIT_CN)
666 err = 0;
667 }
668
669 out:
670 dst_release(dst);
671 return err;
672 }
673
674 /*
675 * IPv4 request_sock destructor.
676 */
677 static void tcp_v4_reqsk_destructor(struct request_sock *req)
678 {
679 kfree(inet_rsk(req)->opt);
680 }
681
682 #ifdef CONFIG_SYN_COOKIES
683 static void syn_flood_warning(struct sk_buff *skb)
684 {
685 static unsigned long warntime;
686
687 if (time_after(jiffies, (warntime + HZ * 60))) {
688 warntime = jiffies;
689 printk(KERN_INFO
690 "possible SYN flooding on port %d. Sending cookies.\n",
691 ntohs(skb->h.th->dest));
692 }
693 }
694 #endif
695
696 /*
697 * Save and compile IPv4 options into the request_sock if needed.
698 */
699 static struct ip_options *tcp_v4_save_options(struct sock *sk,
700 struct sk_buff *skb)
701 {
702 struct ip_options *opt = &(IPCB(skb)->opt);
703 struct ip_options *dopt = NULL;
704
705 if (opt && opt->optlen) {
706 int opt_size = optlength(opt);
707 dopt = kmalloc(opt_size, GFP_ATOMIC);
708 if (dopt) {
709 if (ip_options_echo(dopt, skb)) {
710 kfree(dopt);
711 dopt = NULL;
712 }
713 }
714 }
715 return dopt;
716 }
717
718 struct request_sock_ops tcp_request_sock_ops = {
719 .family = PF_INET,
720 .obj_size = sizeof(struct tcp_request_sock),
721 .rtx_syn_ack = tcp_v4_send_synack,
722 .send_ack = tcp_v4_reqsk_send_ack,
723 .destructor = tcp_v4_reqsk_destructor,
724 .send_reset = tcp_v4_send_reset,
725 };
726
727 static struct timewait_sock_ops tcp_timewait_sock_ops = {
728 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
729 .twsk_unique = tcp_twsk_unique,
730 };
731
732 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
733 {
734 struct inet_request_sock *ireq;
735 struct tcp_options_received tmp_opt;
736 struct request_sock *req;
737 __be32 saddr = skb->nh.iph->saddr;
738 __be32 daddr = skb->nh.iph->daddr;
739 __u32 isn = TCP_SKB_CB(skb)->when;
740 struct dst_entry *dst = NULL;
741 #ifdef CONFIG_SYN_COOKIES
742 int want_cookie = 0;
743 #else
744 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
745 #endif
746
747 /* Never answer to SYNs send to broadcast or multicast */
748 if (((struct rtable *)skb->dst)->rt_flags &
749 (RTCF_BROADCAST | RTCF_MULTICAST))
750 goto drop;
751
752 /* TW buckets are converted to open requests without
753 * limitations, they conserve resources and peer is
754 * evidently real one.
755 */
756 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
757 #ifdef CONFIG_SYN_COOKIES
758 if (sysctl_tcp_syncookies) {
759 want_cookie = 1;
760 } else
761 #endif
762 goto drop;
763 }
764
765 /* Accept backlog is full. If we have already queued enough
766 * of warm entries in syn queue, drop request. It is better than
767 * clogging syn queue with openreqs with exponentially increasing
768 * timeout.
769 */
770 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
771 goto drop;
772
773 req = reqsk_alloc(&tcp_request_sock_ops);
774 if (!req)
775 goto drop;
776
777 tcp_clear_options(&tmp_opt);
778 tmp_opt.mss_clamp = 536;
779 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
780
781 tcp_parse_options(skb, &tmp_opt, 0);
782
783 if (want_cookie) {
784 tcp_clear_options(&tmp_opt);
785 tmp_opt.saw_tstamp = 0;
786 }
787
788 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
789 /* Some OSes (unknown ones, but I see them on web server, which
790 * contains information interesting only for windows'
791 * users) do not send their stamp in SYN. It is easy case.
792 * We simply do not advertise TS support.
793 */
794 tmp_opt.saw_tstamp = 0;
795 tmp_opt.tstamp_ok = 0;
796 }
797 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
798
799 tcp_openreq_init(req, &tmp_opt, skb);
800
801 if (security_inet_conn_request(sk, skb, req))
802 goto drop_and_free;
803
804 ireq = inet_rsk(req);
805 ireq->loc_addr = daddr;
806 ireq->rmt_addr = saddr;
807 ireq->opt = tcp_v4_save_options(sk, skb);
808 if (!want_cookie)
809 TCP_ECN_create_request(req, skb->h.th);
810
811 if (want_cookie) {
812 #ifdef CONFIG_SYN_COOKIES
813 syn_flood_warning(skb);
814 #endif
815 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
816 } else if (!isn) {
817 struct inet_peer *peer = NULL;
818
819 /* VJ's idea. We save last timestamp seen
820 * from the destination in peer table, when entering
821 * state TIME-WAIT, and check against it before
822 * accepting new connection request.
823 *
824 * If "isn" is not zero, this request hit alive
825 * timewait bucket, so that all the necessary checks
826 * are made in the function processing timewait state.
827 */
828 if (tmp_opt.saw_tstamp &&
829 tcp_death_row.sysctl_tw_recycle &&
830 (dst = inet_csk_route_req(sk, req)) != NULL &&
831 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
832 peer->v4daddr == saddr) {
833 if (xtime.tv_sec < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
834 (s32)(peer->tcp_ts - req->ts_recent) >
835 TCP_PAWS_WINDOW) {
836 NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED);
837 dst_release(dst);
838 goto drop_and_free;
839 }
840 }
841 /* Kill the following clause, if you dislike this way. */
842 else if (!sysctl_tcp_syncookies &&
843 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
844 (sysctl_max_syn_backlog >> 2)) &&
845 (!peer || !peer->tcp_ts_stamp) &&
846 (!dst || !dst_metric(dst, RTAX_RTT))) {
847 /* Without syncookies last quarter of
848 * backlog is filled with destinations,
849 * proven to be alive.
850 * It means that we continue to communicate
851 * to destinations, already remembered
852 * to the moment of synflood.
853 */
854 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
855 "request from %u.%u.%u.%u/%u\n",
856 NIPQUAD(saddr),
857 ntohs(skb->h.th->source));
858 dst_release(dst);
859 goto drop_and_free;
860 }
861
862 isn = tcp_v4_init_sequence(sk, skb);
863 }
864 tcp_rsk(req)->snt_isn = isn;
865
866 if (tcp_v4_send_synack(sk, req, dst))
867 goto drop_and_free;
868
869 if (want_cookie) {
870 reqsk_free(req);
871 } else {
872 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
873 }
874 return 0;
875
876 drop_and_free:
877 reqsk_free(req);
878 drop:
879 return 0;
880 }
881
882
883 /*
884 * The three way handshake has completed - we got a valid synack -
885 * now create the new socket.
886 */
887 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
888 struct request_sock *req,
889 struct dst_entry *dst)
890 {
891 struct inet_request_sock *ireq;
892 struct inet_sock *newinet;
893 struct tcp_sock *newtp;
894 struct sock *newsk;
895
896 if (sk_acceptq_is_full(sk))
897 goto exit_overflow;
898
899 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
900 goto exit;
901
902 newsk = tcp_create_openreq_child(sk, req, skb);
903 if (!newsk)
904 goto exit;
905
906 newsk->sk_gso_type = SKB_GSO_TCPV4;
907 sk_setup_caps(newsk, dst);
908
909 newtp = tcp_sk(newsk);
910 newinet = inet_sk(newsk);
911 ireq = inet_rsk(req);
912 newinet->daddr = ireq->rmt_addr;
913 newinet->rcv_saddr = ireq->loc_addr;
914 newinet->saddr = ireq->loc_addr;
915 newinet->opt = ireq->opt;
916 ireq->opt = NULL;
917 newinet->mc_index = inet_iif(skb);
918 newinet->mc_ttl = skb->nh.iph->ttl;
919 inet_csk(newsk)->icsk_ext_hdr_len = 0;
920 if (newinet->opt)
921 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
922 newinet->id = newtp->write_seq ^ jiffies;
923
924 tcp_mtup_init(newsk);
925 tcp_sync_mss(newsk, dst_mtu(dst));
926 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
927 tcp_initialize_rcv_mss(newsk);
928
929 __inet_hash(&tcp_hashinfo, newsk, 0);
930 __inet_inherit_port(&tcp_hashinfo, sk, newsk);
931
932 return newsk;
933
934 exit_overflow:
935 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
936 exit:
937 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
938 dst_release(dst);
939 return NULL;
940 }
941
942 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
943 {
944 struct tcphdr *th = skb->h.th;
945 struct iphdr *iph = skb->nh.iph;
946 struct sock *nsk;
947 struct request_sock **prev;
948 /* Find possible connection requests. */
949 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
950 iph->saddr, iph->daddr);
951 if (req)
952 return tcp_check_req(sk, skb, req, prev);
953
954 nsk = inet_lookup_established(&tcp_hashinfo, skb->nh.iph->saddr,
955 th->source, skb->nh.iph->daddr,
956 th->dest, inet_iif(skb));
957
958 if (nsk) {
959 if (nsk->sk_state != TCP_TIME_WAIT) {
960 bh_lock_sock(nsk);
961 return nsk;
962 }
963 inet_twsk_put(inet_twsk(nsk));
964 return NULL;
965 }
966
967 #ifdef CONFIG_SYN_COOKIES
968 if (!th->rst && !th->syn && th->ack)
969 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
970 #endif
971 return sk;
972 }
973
974 static int tcp_v4_checksum_init(struct sk_buff *skb)
975 {
976 if (skb->ip_summed == CHECKSUM_COMPLETE) {
977 if (!tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
978 skb->nh.iph->daddr, skb->csum)) {
979 skb->ip_summed = CHECKSUM_UNNECESSARY;
980 return 0;
981 }
982 }
983
984 skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr, skb->nh.iph->daddr,
985 skb->len, IPPROTO_TCP, 0);
986
987 if (skb->len <= 76) {
988 return __skb_checksum_complete(skb);
989 }
990 return 0;
991 }
992
993
994 /* The socket must have it's spinlock held when we get
995 * here.
996 *
997 * We have a potential double-lock case here, so even when
998 * doing backlog processing we use the BH locking scheme.
999 * This is because we cannot sleep with the original spinlock
1000 * held.
1001 */
1002 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1003 {
1004 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1005 TCP_CHECK_TIMER(sk);
1006 if (tcp_rcv_established(sk, skb, skb->h.th, skb->len))
1007 goto reset;
1008 TCP_CHECK_TIMER(sk);
1009 return 0;
1010 }
1011
1012 if (skb->len < (skb->h.th->doff << 2) || tcp_checksum_complete(skb))
1013 goto csum_err;
1014
1015 if (sk->sk_state == TCP_LISTEN) {
1016 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1017 if (!nsk)
1018 goto discard;
1019
1020 if (nsk != sk) {
1021 if (tcp_child_process(sk, nsk, skb))
1022 goto reset;
1023 return 0;
1024 }
1025 }
1026
1027 TCP_CHECK_TIMER(sk);
1028 if (tcp_rcv_state_process(sk, skb, skb->h.th, skb->len))
1029 goto reset;
1030 TCP_CHECK_TIMER(sk);
1031 return 0;
1032
1033 reset:
1034 tcp_v4_send_reset(skb);
1035 discard:
1036 kfree_skb(skb);
1037 /* Be careful here. If this function gets more complicated and
1038 * gcc suffers from register pressure on the x86, sk (in %ebx)
1039 * might be destroyed here. This current version compiles correctly,
1040 * but you have been warned.
1041 */
1042 return 0;
1043
1044 csum_err:
1045 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1046 goto discard;
1047 }
1048
1049 /*
1050 * From tcp_input.c
1051 */
1052
1053 int tcp_v4_rcv(struct sk_buff *skb)
1054 {
1055 struct tcphdr *th;
1056 struct sock *sk;
1057 int ret;
1058
1059 if (skb->pkt_type != PACKET_HOST)
1060 goto discard_it;
1061
1062 /* Count it even if it's bad */
1063 TCP_INC_STATS_BH(TCP_MIB_INSEGS);
1064
1065 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1066 goto discard_it;
1067
1068 th = skb->h.th;
1069
1070 if (th->doff < sizeof(struct tcphdr) / 4)
1071 goto bad_packet;
1072 if (!pskb_may_pull(skb, th->doff * 4))
1073 goto discard_it;
1074
1075 /* An explanation is required here, I think.
1076 * Packet length and doff are validated by header prediction,
1077 * provided case of th->doff==0 is eliminated.
1078 * So, we defer the checks. */
1079 if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
1080 tcp_v4_checksum_init(skb)))
1081 goto bad_packet;
1082
1083 th = skb->h.th;
1084 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1085 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1086 skb->len - th->doff * 4);
1087 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1088 TCP_SKB_CB(skb)->when = 0;
1089 TCP_SKB_CB(skb)->flags = skb->nh.iph->tos;
1090 TCP_SKB_CB(skb)->sacked = 0;
1091
1092 sk = __inet_lookup(&tcp_hashinfo, skb->nh.iph->saddr, th->source,
1093 skb->nh.iph->daddr, th->dest,
1094 inet_iif(skb));
1095
1096 if (!sk)
1097 goto no_tcp_socket;
1098
1099 process:
1100 if (sk->sk_state == TCP_TIME_WAIT)
1101 goto do_time_wait;
1102
1103 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1104 goto discard_and_relse;
1105 nf_reset(skb);
1106
1107 if (sk_filter(sk, skb))
1108 goto discard_and_relse;
1109
1110 skb->dev = NULL;
1111
1112 bh_lock_sock_nested(sk);
1113 ret = 0;
1114 if (!sock_owned_by_user(sk)) {
1115 #ifdef CONFIG_NET_DMA
1116 struct tcp_sock *tp = tcp_sk(sk);
1117 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1118 tp->ucopy.dma_chan = get_softnet_dma();
1119 if (tp->ucopy.dma_chan)
1120 ret = tcp_v4_do_rcv(sk, skb);
1121 else
1122 #endif
1123 {
1124 if (!tcp_prequeue(sk, skb))
1125 ret = tcp_v4_do_rcv(sk, skb);
1126 }
1127 } else
1128 sk_add_backlog(sk, skb);
1129 bh_unlock_sock(sk);
1130
1131 sock_put(sk);
1132
1133 return ret;
1134
1135 no_tcp_socket:
1136 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1137 goto discard_it;
1138
1139 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1140 bad_packet:
1141 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1142 } else {
1143 tcp_v4_send_reset(skb);
1144 }
1145
1146 discard_it:
1147 /* Discard frame. */
1148 kfree_skb(skb);
1149 return 0;
1150
1151 discard_and_relse:
1152 sock_put(sk);
1153 goto discard_it;
1154
1155 do_time_wait:
1156 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1157 inet_twsk_put(inet_twsk(sk));
1158 goto discard_it;
1159 }
1160
1161 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1162 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1163 inet_twsk_put(inet_twsk(sk));
1164 goto discard_it;
1165 }
1166 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1167 case TCP_TW_SYN: {
1168 struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
1169 skb->nh.iph->daddr,
1170 th->dest,
1171 inet_iif(skb));
1172 if (sk2) {
1173 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1174 inet_twsk_put(inet_twsk(sk));
1175 sk = sk2;
1176 goto process;
1177 }
1178 /* Fall through to ACK */
1179 }
1180 case TCP_TW_ACK:
1181 tcp_v4_timewait_ack(sk, skb);
1182 break;
1183 case TCP_TW_RST:
1184 goto no_tcp_socket;
1185 case TCP_TW_SUCCESS:;
1186 }
1187 goto discard_it;
1188 }
1189
1190 /* VJ's idea. Save last timestamp seen from this destination
1191 * and hold it at least for normal timewait interval to use for duplicate
1192 * segment detection in subsequent connections, before they enter synchronized
1193 * state.
1194 */
1195
1196 int tcp_v4_remember_stamp(struct sock *sk)
1197 {
1198 struct inet_sock *inet = inet_sk(sk);
1199 struct tcp_sock *tp = tcp_sk(sk);
1200 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1201 struct inet_peer *peer = NULL;
1202 int release_it = 0;
1203
1204 if (!rt || rt->rt_dst != inet->daddr) {
1205 peer = inet_getpeer(inet->daddr, 1);
1206 release_it = 1;
1207 } else {
1208 if (!rt->peer)
1209 rt_bind_peer(rt, 1);
1210 peer = rt->peer;
1211 }
1212
1213 if (peer) {
1214 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1215 (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
1216 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1217 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1218 peer->tcp_ts = tp->rx_opt.ts_recent;
1219 }
1220 if (release_it)
1221 inet_putpeer(peer);
1222 return 1;
1223 }
1224
1225 return 0;
1226 }
1227
1228 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1229 {
1230 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1231
1232 if (peer) {
1233 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1234
1235 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1236 (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
1237 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1238 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1239 peer->tcp_ts = tcptw->tw_ts_recent;
1240 }
1241 inet_putpeer(peer);
1242 return 1;
1243 }
1244
1245 return 0;
1246 }
1247
1248 struct inet_connection_sock_af_ops ipv4_specific = {
1249 .queue_xmit = ip_queue_xmit,
1250 .send_check = tcp_v4_send_check,
1251 .rebuild_header = inet_sk_rebuild_header,
1252 .conn_request = tcp_v4_conn_request,
1253 .syn_recv_sock = tcp_v4_syn_recv_sock,
1254 .remember_stamp = tcp_v4_remember_stamp,
1255 .net_header_len = sizeof(struct iphdr),
1256 .setsockopt = ip_setsockopt,
1257 .getsockopt = ip_getsockopt,
1258 .addr2sockaddr = inet_csk_addr2sockaddr,
1259 .sockaddr_len = sizeof(struct sockaddr_in),
1260 #ifdef CONFIG_COMPAT
1261 .compat_setsockopt = compat_ip_setsockopt,
1262 .compat_getsockopt = compat_ip_getsockopt,
1263 #endif
1264 };
1265
1266 /* NOTE: A lot of things set to zero explicitly by call to
1267 * sk_alloc() so need not be done here.
1268 */
1269 static int tcp_v4_init_sock(struct sock *sk)
1270 {
1271 struct inet_connection_sock *icsk = inet_csk(sk);
1272 struct tcp_sock *tp = tcp_sk(sk);
1273
1274 skb_queue_head_init(&tp->out_of_order_queue);
1275 tcp_init_xmit_timers(sk);
1276 tcp_prequeue_init(tp);
1277
1278 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1279 tp->mdev = TCP_TIMEOUT_INIT;
1280
1281 /* So many TCP implementations out there (incorrectly) count the
1282 * initial SYN frame in their delayed-ACK and congestion control
1283 * algorithms that we must have the following bandaid to talk
1284 * efficiently to them. -DaveM
1285 */
1286 tp->snd_cwnd = 2;
1287
1288 /* See draft-stevens-tcpca-spec-01 for discussion of the
1289 * initialization of these values.
1290 */
1291 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1292 tp->snd_cwnd_clamp = ~0;
1293 tp->mss_cache = 536;
1294
1295 tp->reordering = sysctl_tcp_reordering;
1296 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1297
1298 sk->sk_state = TCP_CLOSE;
1299
1300 sk->sk_write_space = sk_stream_write_space;
1301 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1302
1303 icsk->icsk_af_ops = &ipv4_specific;
1304 icsk->icsk_sync_mss = tcp_sync_mss;
1305
1306 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1307 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1308
1309 atomic_inc(&tcp_sockets_allocated);
1310
1311 return 0;
1312 }
1313
1314 int tcp_v4_destroy_sock(struct sock *sk)
1315 {
1316 struct tcp_sock *tp = tcp_sk(sk);
1317
1318 tcp_clear_xmit_timers(sk);
1319
1320 tcp_cleanup_congestion_control(sk);
1321
1322 /* Cleanup up the write buffer. */
1323 sk_stream_writequeue_purge(sk);
1324
1325 /* Cleans up our, hopefully empty, out_of_order_queue. */
1326 __skb_queue_purge(&tp->out_of_order_queue);
1327
1328 #ifdef CONFIG_NET_DMA
1329 /* Cleans up our sk_async_wait_queue */
1330 __skb_queue_purge(&sk->sk_async_wait_queue);
1331 #endif
1332
1333 /* Clean prequeue, it must be empty really */
1334 __skb_queue_purge(&tp->ucopy.prequeue);
1335
1336 /* Clean up a referenced TCP bind bucket. */
1337 if (inet_csk(sk)->icsk_bind_hash)
1338 inet_put_port(&tcp_hashinfo, sk);
1339
1340 /*
1341 * If sendmsg cached page exists, toss it.
1342 */
1343 if (sk->sk_sndmsg_page) {
1344 __free_page(sk->sk_sndmsg_page);
1345 sk->sk_sndmsg_page = NULL;
1346 }
1347
1348 atomic_dec(&tcp_sockets_allocated);
1349
1350 return 0;
1351 }
1352
1353 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1354
1355 #ifdef CONFIG_PROC_FS
1356 /* Proc filesystem TCP sock list dumping. */
1357
1358 static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
1359 {
1360 return hlist_empty(head) ? NULL :
1361 list_entry(head->first, struct inet_timewait_sock, tw_node);
1362 }
1363
1364 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1365 {
1366 return tw->tw_node.next ?
1367 hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1368 }
1369
1370 static void *listening_get_next(struct seq_file *seq, void *cur)
1371 {
1372 struct inet_connection_sock *icsk;
1373 struct hlist_node *node;
1374 struct sock *sk = cur;
1375 struct tcp_iter_state* st = seq->private;
1376
1377 if (!sk) {
1378 st->bucket = 0;
1379 sk = sk_head(&tcp_hashinfo.listening_hash[0]);
1380 goto get_sk;
1381 }
1382
1383 ++st->num;
1384
1385 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1386 struct request_sock *req = cur;
1387
1388 icsk = inet_csk(st->syn_wait_sk);
1389 req = req->dl_next;
1390 while (1) {
1391 while (req) {
1392 if (req->rsk_ops->family == st->family) {
1393 cur = req;
1394 goto out;
1395 }
1396 req = req->dl_next;
1397 }
1398 if (++st->sbucket >= TCP_SYNQ_HSIZE)
1399 break;
1400 get_req:
1401 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1402 }
1403 sk = sk_next(st->syn_wait_sk);
1404 st->state = TCP_SEQ_STATE_LISTENING;
1405 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1406 } else {
1407 icsk = inet_csk(sk);
1408 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1409 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1410 goto start_req;
1411 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1412 sk = sk_next(sk);
1413 }
1414 get_sk:
1415 sk_for_each_from(sk, node) {
1416 if (sk->sk_family == st->family) {
1417 cur = sk;
1418 goto out;
1419 }
1420 icsk = inet_csk(sk);
1421 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1422 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1423 start_req:
1424 st->uid = sock_i_uid(sk);
1425 st->syn_wait_sk = sk;
1426 st->state = TCP_SEQ_STATE_OPENREQ;
1427 st->sbucket = 0;
1428 goto get_req;
1429 }
1430 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1431 }
1432 if (++st->bucket < INET_LHTABLE_SIZE) {
1433 sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
1434 goto get_sk;
1435 }
1436 cur = NULL;
1437 out:
1438 return cur;
1439 }
1440
1441 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1442 {
1443 void *rc = listening_get_next(seq, NULL);
1444
1445 while (rc && *pos) {
1446 rc = listening_get_next(seq, rc);
1447 --*pos;
1448 }
1449 return rc;
1450 }
1451
1452 static void *established_get_first(struct seq_file *seq)
1453 {
1454 struct tcp_iter_state* st = seq->private;
1455 void *rc = NULL;
1456
1457 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1458 struct sock *sk;
1459 struct hlist_node *node;
1460 struct inet_timewait_sock *tw;
1461
1462 /* We can reschedule _before_ having picked the target: */
1463 cond_resched_softirq();
1464
1465 read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
1466 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1467 if (sk->sk_family != st->family) {
1468 continue;
1469 }
1470 rc = sk;
1471 goto out;
1472 }
1473 st->state = TCP_SEQ_STATE_TIME_WAIT;
1474 inet_twsk_for_each(tw, node,
1475 &tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain) {
1476 if (tw->tw_family != st->family) {
1477 continue;
1478 }
1479 rc = tw;
1480 goto out;
1481 }
1482 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1483 st->state = TCP_SEQ_STATE_ESTABLISHED;
1484 }
1485 out:
1486 return rc;
1487 }
1488
1489 static void *established_get_next(struct seq_file *seq, void *cur)
1490 {
1491 struct sock *sk = cur;
1492 struct inet_timewait_sock *tw;
1493 struct hlist_node *node;
1494 struct tcp_iter_state* st = seq->private;
1495
1496 ++st->num;
1497
1498 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
1499 tw = cur;
1500 tw = tw_next(tw);
1501 get_tw:
1502 while (tw && tw->tw_family != st->family) {
1503 tw = tw_next(tw);
1504 }
1505 if (tw) {
1506 cur = tw;
1507 goto out;
1508 }
1509 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1510 st->state = TCP_SEQ_STATE_ESTABLISHED;
1511
1512 /* We can reschedule between buckets: */
1513 cond_resched_softirq();
1514
1515 if (++st->bucket < tcp_hashinfo.ehash_size) {
1516 read_lock(&tcp_hashinfo.ehash[st->bucket].lock);
1517 sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
1518 } else {
1519 cur = NULL;
1520 goto out;
1521 }
1522 } else
1523 sk = sk_next(sk);
1524
1525 sk_for_each_from(sk, node) {
1526 if (sk->sk_family == st->family)
1527 goto found;
1528 }
1529
1530 st->state = TCP_SEQ_STATE_TIME_WAIT;
1531 tw = tw_head(&tcp_hashinfo.ehash[st->bucket + tcp_hashinfo.ehash_size].chain);
1532 goto get_tw;
1533 found:
1534 cur = sk;
1535 out:
1536 return cur;
1537 }
1538
1539 static void *established_get_idx(struct seq_file *seq, loff_t pos)
1540 {
1541 void *rc = established_get_first(seq);
1542
1543 while (rc && pos) {
1544 rc = established_get_next(seq, rc);
1545 --pos;
1546 }
1547 return rc;
1548 }
1549
1550 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
1551 {
1552 void *rc;
1553 struct tcp_iter_state* st = seq->private;
1554
1555 inet_listen_lock(&tcp_hashinfo);
1556 st->state = TCP_SEQ_STATE_LISTENING;
1557 rc = listening_get_idx(seq, &pos);
1558
1559 if (!rc) {
1560 inet_listen_unlock(&tcp_hashinfo);
1561 local_bh_disable();
1562 st->state = TCP_SEQ_STATE_ESTABLISHED;
1563 rc = established_get_idx(seq, pos);
1564 }
1565
1566 return rc;
1567 }
1568
1569 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
1570 {
1571 struct tcp_iter_state* st = seq->private;
1572 st->state = TCP_SEQ_STATE_LISTENING;
1573 st->num = 0;
1574 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1575 }
1576
1577 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1578 {
1579 void *rc = NULL;
1580 struct tcp_iter_state* st;
1581
1582 if (v == SEQ_START_TOKEN) {
1583 rc = tcp_get_idx(seq, 0);
1584 goto out;
1585 }
1586 st = seq->private;
1587
1588 switch (st->state) {
1589 case TCP_SEQ_STATE_OPENREQ:
1590 case TCP_SEQ_STATE_LISTENING:
1591 rc = listening_get_next(seq, v);
1592 if (!rc) {
1593 inet_listen_unlock(&tcp_hashinfo);
1594 local_bh_disable();
1595 st->state = TCP_SEQ_STATE_ESTABLISHED;
1596 rc = established_get_first(seq);
1597 }
1598 break;
1599 case TCP_SEQ_STATE_ESTABLISHED:
1600 case TCP_SEQ_STATE_TIME_WAIT:
1601 rc = established_get_next(seq, v);
1602 break;
1603 }
1604 out:
1605 ++*pos;
1606 return rc;
1607 }
1608
1609 static void tcp_seq_stop(struct seq_file *seq, void *v)
1610 {
1611 struct tcp_iter_state* st = seq->private;
1612
1613 switch (st->state) {
1614 case TCP_SEQ_STATE_OPENREQ:
1615 if (v) {
1616 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
1617 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1618 }
1619 case TCP_SEQ_STATE_LISTENING:
1620 if (v != SEQ_START_TOKEN)
1621 inet_listen_unlock(&tcp_hashinfo);
1622 break;
1623 case TCP_SEQ_STATE_TIME_WAIT:
1624 case TCP_SEQ_STATE_ESTABLISHED:
1625 if (v)
1626 read_unlock(&tcp_hashinfo.ehash[st->bucket].lock);
1627 local_bh_enable();
1628 break;
1629 }
1630 }
1631
1632 static int tcp_seq_open(struct inode *inode, struct file *file)
1633 {
1634 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
1635 struct seq_file *seq;
1636 struct tcp_iter_state *s;
1637 int rc;
1638
1639 if (unlikely(afinfo == NULL))
1640 return -EINVAL;
1641
1642 s = kzalloc(sizeof(*s), GFP_KERNEL);
1643 if (!s)
1644 return -ENOMEM;
1645 s->family = afinfo->family;
1646 s->seq_ops.start = tcp_seq_start;
1647 s->seq_ops.next = tcp_seq_next;
1648 s->seq_ops.show = afinfo->seq_show;
1649 s->seq_ops.stop = tcp_seq_stop;
1650
1651 rc = seq_open(file, &s->seq_ops);
1652 if (rc)
1653 goto out_kfree;
1654 seq = file->private_data;
1655 seq->private = s;
1656 out:
1657 return rc;
1658 out_kfree:
1659 kfree(s);
1660 goto out;
1661 }
1662
1663 int tcp_proc_register(struct tcp_seq_afinfo *afinfo)
1664 {
1665 int rc = 0;
1666 struct proc_dir_entry *p;
1667
1668 if (!afinfo)
1669 return -EINVAL;
1670 afinfo->seq_fops->owner = afinfo->owner;
1671 afinfo->seq_fops->open = tcp_seq_open;
1672 afinfo->seq_fops->read = seq_read;
1673 afinfo->seq_fops->llseek = seq_lseek;
1674 afinfo->seq_fops->release = seq_release_private;
1675
1676 p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops);
1677 if (p)
1678 p->data = afinfo;
1679 else
1680 rc = -ENOMEM;
1681 return rc;
1682 }
1683
1684 void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
1685 {
1686 if (!afinfo)
1687 return;
1688 proc_net_remove(afinfo->name);
1689 memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
1690 }
1691
1692 static void get_openreq4(struct sock *sk, struct request_sock *req,
1693 char *tmpbuf, int i, int uid)
1694 {
1695 const struct inet_request_sock *ireq = inet_rsk(req);
1696 int ttd = req->expires - jiffies;
1697
1698 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
1699 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
1700 i,
1701 ireq->loc_addr,
1702 ntohs(inet_sk(sk)->sport),
1703 ireq->rmt_addr,
1704 ntohs(ireq->rmt_port),
1705 TCP_SYN_RECV,
1706 0, 0, /* could print option size, but that is af dependent. */
1707 1, /* timers active (only the expire timer) */
1708 jiffies_to_clock_t(ttd),
1709 req->retrans,
1710 uid,
1711 0, /* non standard timer */
1712 0, /* open_requests have no inode */
1713 atomic_read(&sk->sk_refcnt),
1714 req);
1715 }
1716
1717 static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i)
1718 {
1719 int timer_active;
1720 unsigned long timer_expires;
1721 struct tcp_sock *tp = tcp_sk(sp);
1722 const struct inet_connection_sock *icsk = inet_csk(sp);
1723 struct inet_sock *inet = inet_sk(sp);
1724 unsigned int dest = inet->daddr;
1725 unsigned int src = inet->rcv_saddr;
1726 __u16 destp = ntohs(inet->dport);
1727 __u16 srcp = ntohs(inet->sport);
1728
1729 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
1730 timer_active = 1;
1731 timer_expires = icsk->icsk_timeout;
1732 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
1733 timer_active = 4;
1734 timer_expires = icsk->icsk_timeout;
1735 } else if (timer_pending(&sp->sk_timer)) {
1736 timer_active = 2;
1737 timer_expires = sp->sk_timer.expires;
1738 } else {
1739 timer_active = 0;
1740 timer_expires = jiffies;
1741 }
1742
1743 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
1744 "%08X %5d %8d %lu %d %p %u %u %u %u %d",
1745 i, src, srcp, dest, destp, sp->sk_state,
1746 tp->write_seq - tp->snd_una,
1747 (sp->sk_state == TCP_LISTEN) ? sp->sk_ack_backlog : (tp->rcv_nxt - tp->copied_seq),
1748 timer_active,
1749 jiffies_to_clock_t(timer_expires - jiffies),
1750 icsk->icsk_retransmits,
1751 sock_i_uid(sp),
1752 icsk->icsk_probes_out,
1753 sock_i_ino(sp),
1754 atomic_read(&sp->sk_refcnt), sp,
1755 icsk->icsk_rto,
1756 icsk->icsk_ack.ato,
1757 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
1758 tp->snd_cwnd,
1759 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh);
1760 }
1761
1762 static void get_timewait4_sock(struct inet_timewait_sock *tw, char *tmpbuf, int i)
1763 {
1764 __be32 dest, src;
1765 __u16 destp, srcp;
1766 int ttd = tw->tw_ttd - jiffies;
1767
1768 if (ttd < 0)
1769 ttd = 0;
1770
1771 dest = tw->tw_daddr;
1772 src = tw->tw_rcv_saddr;
1773 destp = ntohs(tw->tw_dport);
1774 srcp = ntohs(tw->tw_sport);
1775
1776 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
1777 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p",
1778 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
1779 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
1780 atomic_read(&tw->tw_refcnt), tw);
1781 }
1782
1783 #define TMPSZ 150
1784
1785 static int tcp4_seq_show(struct seq_file *seq, void *v)
1786 {
1787 struct tcp_iter_state* st;
1788 char tmpbuf[TMPSZ + 1];
1789
1790 if (v == SEQ_START_TOKEN) {
1791 seq_printf(seq, "%-*s\n", TMPSZ - 1,
1792 " sl local_address rem_address st tx_queue "
1793 "rx_queue tr tm->when retrnsmt uid timeout "
1794 "inode");
1795 goto out;
1796 }
1797 st = seq->private;
1798
1799 switch (st->state) {
1800 case TCP_SEQ_STATE_LISTENING:
1801 case TCP_SEQ_STATE_ESTABLISHED:
1802 get_tcp4_sock(v, tmpbuf, st->num);
1803 break;
1804 case TCP_SEQ_STATE_OPENREQ:
1805 get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid);
1806 break;
1807 case TCP_SEQ_STATE_TIME_WAIT:
1808 get_timewait4_sock(v, tmpbuf, st->num);
1809 break;
1810 }
1811 seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf);
1812 out:
1813 return 0;
1814 }
1815
1816 static struct file_operations tcp4_seq_fops;
1817 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
1818 .owner = THIS_MODULE,
1819 .name = "tcp",
1820 .family = AF_INET,
1821 .seq_show = tcp4_seq_show,
1822 .seq_fops = &tcp4_seq_fops,
1823 };
1824
1825 int __init tcp4_proc_init(void)
1826 {
1827 return tcp_proc_register(&tcp4_seq_afinfo);
1828 }
1829
1830 void tcp4_proc_exit(void)
1831 {
1832 tcp_proc_unregister(&tcp4_seq_afinfo);
1833 }
1834 #endif /* CONFIG_PROC_FS */
1835
1836 struct proto tcp_prot = {
1837 .name = "TCP",
1838 .owner = THIS_MODULE,
1839 .close = tcp_close,
1840 .connect = tcp_v4_connect,
1841 .disconnect = tcp_disconnect,
1842 .accept = inet_csk_accept,
1843 .ioctl = tcp_ioctl,
1844 .init = tcp_v4_init_sock,
1845 .destroy = tcp_v4_destroy_sock,
1846 .shutdown = tcp_shutdown,
1847 .setsockopt = tcp_setsockopt,
1848 .getsockopt = tcp_getsockopt,
1849 .sendmsg = tcp_sendmsg,
1850 .recvmsg = tcp_recvmsg,
1851 .backlog_rcv = tcp_v4_do_rcv,
1852 .hash = tcp_v4_hash,
1853 .unhash = tcp_unhash,
1854 .get_port = tcp_v4_get_port,
1855 .enter_memory_pressure = tcp_enter_memory_pressure,
1856 .sockets_allocated = &tcp_sockets_allocated,
1857 .orphan_count = &tcp_orphan_count,
1858 .memory_allocated = &tcp_memory_allocated,
1859 .memory_pressure = &tcp_memory_pressure,
1860 .sysctl_mem = sysctl_tcp_mem,
1861 .sysctl_wmem = sysctl_tcp_wmem,
1862 .sysctl_rmem = sysctl_tcp_rmem,
1863 .max_header = MAX_TCP_HEADER,
1864 .obj_size = sizeof(struct tcp_sock),
1865 .twsk_prot = &tcp_timewait_sock_ops,
1866 .rsk_prot = &tcp_request_sock_ops,
1867 #ifdef CONFIG_COMPAT
1868 .compat_setsockopt = compat_tcp_setsockopt,
1869 .compat_getsockopt = compat_tcp_getsockopt,
1870 #endif
1871 };
1872
1873 void __init tcp_v4_init(struct net_proto_family *ops)
1874 {
1875 if (inet_csk_ctl_sock_create(&tcp_socket, PF_INET, SOCK_RAW, IPPROTO_TCP) < 0)
1876 panic("Failed to create the TCP control socket.\n");
1877 }
1878
1879 EXPORT_SYMBOL(ipv4_specific);
1880 EXPORT_SYMBOL(tcp_hashinfo);
1881 EXPORT_SYMBOL(tcp_prot);
1882 EXPORT_SYMBOL(tcp_unhash);
1883 EXPORT_SYMBOL(tcp_v4_conn_request);
1884 EXPORT_SYMBOL(tcp_v4_connect);
1885 EXPORT_SYMBOL(tcp_v4_do_rcv);
1886 EXPORT_SYMBOL(tcp_v4_remember_stamp);
1887 EXPORT_SYMBOL(tcp_v4_send_check);
1888 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1889
1890 #ifdef CONFIG_PROC_FS
1891 EXPORT_SYMBOL(tcp_proc_register);
1892 EXPORT_SYMBOL(tcp_proc_unregister);
1893 #endif
1894 EXPORT_SYMBOL(sysctl_local_port_range);
1895 EXPORT_SYMBOL(sysctl_tcp_low_latency);
1896
CRIS linux kernel tree