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Pull bugzilla-9429 into release branch
[wrt350n-kernel.git] / net / ipv4 / tcp_ipv4.c
blob652c32368cccb6cb590c2c4eec96b77026288d0b
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/net_namespace.h>
66 #include <net/icmp.h>
67 #include <net/inet_hashtables.h>
68 #include <net/tcp.h>
69 #include <net/transp_v6.h>
70 #include <net/ipv6.h>
71 #include <net/inet_common.h>
72 #include <net/timewait_sock.h>
73 #include <net/xfrm.h>
74 #include <net/netdma.h>
75
76 #include <linux/inet.h>
77 #include <linux/ipv6.h>
78 #include <linux/stddef.h>
79 #include <linux/proc_fs.h>
80 #include <linux/seq_file.h>
81
82 #include <linux/crypto.h>
83 #include <linux/scatterlist.h>
84
85 int sysctl_tcp_tw_reuse __read_mostly;
86 int sysctl_tcp_low_latency __read_mostly;
87
88 /* Check TCP sequence numbers in ICMP packets. */
89 #define ICMP_MIN_LENGTH 8
90
91 /* Socket used for sending RSTs */
92 static struct socket *tcp_socket __read_mostly;
93
94 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
95
96 #ifdef CONFIG_TCP_MD5SIG
97 static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
98 __be32 addr);
99 static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
100 __be32 saddr, __be32 daddr,
101 struct tcphdr *th, int protocol,
102 int tcplen);
103 #endif
104
105 struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
106 .lhash_lock = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
107 .lhash_users = ATOMIC_INIT(0),
108 .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
109 };
110
111 static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
112 {
113 return inet_csk_get_port(&tcp_hashinfo, sk, snum,
114 inet_csk_bind_conflict);
115 }
116
117 static void tcp_v4_hash(struct sock *sk)
118 {
119 inet_hash(&tcp_hashinfo, sk);
120 }
121
122 void tcp_unhash(struct sock *sk)
123 {
124 inet_unhash(&tcp_hashinfo, sk);
125 }
126
127 static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
128 {
129 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
130 ip_hdr(skb)->saddr,
131 tcp_hdr(skb)->dest,
132 tcp_hdr(skb)->source);
133 }
134
135 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
136 {
137 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
138 struct tcp_sock *tp = tcp_sk(sk);
139
140 /* With PAWS, it is safe from the viewpoint
141 of data integrity. Even without PAWS it is safe provided sequence
142 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
143
144 Actually, the idea is close to VJ's one, only timestamp cache is
145 held not per host, but per port pair and TW bucket is used as state
146 holder.
147
148 If TW bucket has been already destroyed we fall back to VJ's scheme
149 and use initial timestamp retrieved from peer table.
150 */
151 if (tcptw->tw_ts_recent_stamp &&
152 (twp == NULL || (sysctl_tcp_tw_reuse &&
153 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
154 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
155 if (tp->write_seq == 0)
156 tp->write_seq = 1;
157 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
158 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
159 sock_hold(sktw);
160 return 1;
161 }
162
163 return 0;
164 }
165
166 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
167
168 /* This will initiate an outgoing connection. */
169 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
170 {
171 struct inet_sock *inet = inet_sk(sk);
172 struct tcp_sock *tp = tcp_sk(sk);
173 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
174 struct rtable *rt;
175 __be32 daddr, nexthop;
176 int tmp;
177 int err;
178
179 if (addr_len < sizeof(struct sockaddr_in))
180 return -EINVAL;
181
182 if (usin->sin_family != AF_INET)
183 return -EAFNOSUPPORT;
184
185 nexthop = daddr = usin->sin_addr.s_addr;
186 if (inet->opt && inet->opt->srr) {
187 if (!daddr)
188 return -EINVAL;
189 nexthop = inet->opt->faddr;
190 }
191
192 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
193 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
194 IPPROTO_TCP,
195 inet->sport, usin->sin_port, sk, 1);
196 if (tmp < 0) {
197 if (tmp == -ENETUNREACH)
198 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
199 return tmp;
200 }
201
202 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
203 ip_rt_put(rt);
204 return -ENETUNREACH;
205 }
206
207 if (!inet->opt || !inet->opt->srr)
208 daddr = rt->rt_dst;
209
210 if (!inet->saddr)
211 inet->saddr = rt->rt_src;
212 inet->rcv_saddr = inet->saddr;
213
214 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
215 /* Reset inherited state */
216 tp->rx_opt.ts_recent = 0;
217 tp->rx_opt.ts_recent_stamp = 0;
218 tp->write_seq = 0;
219 }
220
221 if (tcp_death_row.sysctl_tw_recycle &&
222 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
223 struct inet_peer *peer = rt_get_peer(rt);
224 /*
225 * VJ's idea. We save last timestamp seen from
226 * the destination in peer table, when entering state
227 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
228 * when trying new connection.
229 */
230 if (peer != NULL &&
231 peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {
232 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
233 tp->rx_opt.ts_recent = peer->tcp_ts;
234 }
235 }
236
237 inet->dport = usin->sin_port;
238 inet->daddr = daddr;
239
240 inet_csk(sk)->icsk_ext_hdr_len = 0;
241 if (inet->opt)
242 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
243
244 tp->rx_opt.mss_clamp = 536;
245
246 /* Socket identity is still unknown (sport may be zero).
247 * However we set state to SYN-SENT and not releasing socket
248 * lock select source port, enter ourselves into the hash tables and
249 * complete initialization after this.
250 */
251 tcp_set_state(sk, TCP_SYN_SENT);
252 err = inet_hash_connect(&tcp_death_row, sk);
253 if (err)
254 goto failure;
255
256 err = ip_route_newports(&rt, IPPROTO_TCP,
257 inet->sport, inet->dport, sk);
258 if (err)
259 goto failure;
260
261 /* OK, now commit destination to socket. */
262 sk->sk_gso_type = SKB_GSO_TCPV4;
263 sk_setup_caps(sk, &rt->u.dst);
264
265 if (!tp->write_seq)
266 tp->write_seq = secure_tcp_sequence_number(inet->saddr,
267 inet->daddr,
268 inet->sport,
269 usin->sin_port);
270
271 inet->id = tp->write_seq ^ jiffies;
272
273 err = tcp_connect(sk);
274 rt = NULL;
275 if (err)
276 goto failure;
277
278 return 0;
279
280 failure:
281 /*
282 * This unhashes the socket and releases the local port,
283 * if necessary.
284 */
285 tcp_set_state(sk, TCP_CLOSE);
286 ip_rt_put(rt);
287 sk->sk_route_caps = 0;
288 inet->dport = 0;
289 return err;
290 }
291
292 /*
293 * This routine does path mtu discovery as defined in RFC1191.
294 */
295 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu)
296 {
297 struct dst_entry *dst;
298 struct inet_sock *inet = inet_sk(sk);
299
300 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
301 * send out by Linux are always <576bytes so they should go through
302 * unfragmented).
303 */
304 if (sk->sk_state == TCP_LISTEN)
305 return;
306
307 /* We don't check in the destentry if pmtu discovery is forbidden
308 * on this route. We just assume that no packet_to_big packets
309 * are send back when pmtu discovery is not active.
310 * There is a small race when the user changes this flag in the
311 * route, but I think that's acceptable.
312 */
313 if ((dst = __sk_dst_check(sk, 0)) == NULL)
314 return;
315
316 dst->ops->update_pmtu(dst, mtu);
317
318 /* Something is about to be wrong... Remember soft error
319 * for the case, if this connection will not able to recover.
320 */
321 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
322 sk->sk_err_soft = EMSGSIZE;
323
324 mtu = dst_mtu(dst);
325
326 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
327 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
328 tcp_sync_mss(sk, mtu);
329
330 /* Resend the TCP packet because it's
331 * clear that the old packet has been
332 * dropped. This is the new "fast" path mtu
333 * discovery.
334 */
335 tcp_simple_retransmit(sk);
336 } /* else let the usual retransmit timer handle it */
337 }
338
339 /*
340 * This routine is called by the ICMP module when it gets some
341 * sort of error condition. If err < 0 then the socket should
342 * be closed and the error returned to the user. If err > 0
343 * it's just the icmp type << 8 | icmp code. After adjustment
344 * header points to the first 8 bytes of the tcp header. We need
345 * to find the appropriate port.
346 *
347 * The locking strategy used here is very "optimistic". When
348 * someone else accesses the socket the ICMP is just dropped
349 * and for some paths there is no check at all.
350 * A more general error queue to queue errors for later handling
351 * is probably better.
352 *
353 */
354
355 void tcp_v4_err(struct sk_buff *skb, u32 info)
356 {
357 struct iphdr *iph = (struct iphdr *)skb->data;
358 struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
359 struct tcp_sock *tp;
360 struct inet_sock *inet;
361 const int type = icmp_hdr(skb)->type;
362 const int code = icmp_hdr(skb)->code;
363 struct sock *sk;
364 __u32 seq;
365 int err;
366
367 if (skb->len < (iph->ihl << 2) + 8) {
368 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
369 return;
370 }
371
372 sk = inet_lookup(&tcp_hashinfo, iph->daddr, th->dest, iph->saddr,
373 th->source, inet_iif(skb));
374 if (!sk) {
375 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
376 return;
377 }
378 if (sk->sk_state == TCP_TIME_WAIT) {
379 inet_twsk_put(inet_twsk(sk));
380 return;
381 }
382
383 bh_lock_sock(sk);
384 /* If too many ICMPs get dropped on busy
385 * servers this needs to be solved differently.
386 */
387 if (sock_owned_by_user(sk))
388 NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
389
390 if (sk->sk_state == TCP_CLOSE)
391 goto out;
392
393 tp = tcp_sk(sk);
394 seq = ntohl(th->seq);
395 if (sk->sk_state != TCP_LISTEN &&
396 !between(seq, tp->snd_una, tp->snd_nxt)) {
397 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
398 goto out;
399 }
400
401 switch (type) {
402 case ICMP_SOURCE_QUENCH:
403 /* Just silently ignore these. */
404 goto out;
405 case ICMP_PARAMETERPROB:
406 err = EPROTO;
407 break;
408 case ICMP_DEST_UNREACH:
409 if (code > NR_ICMP_UNREACH)
410 goto out;
411
412 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
413 if (!sock_owned_by_user(sk))
414 do_pmtu_discovery(sk, iph, info);
415 goto out;
416 }
417
418 err = icmp_err_convert[code].errno;
419 break;
420 case ICMP_TIME_EXCEEDED:
421 err = EHOSTUNREACH;
422 break;
423 default:
424 goto out;
425 }
426
427 switch (sk->sk_state) {
428 struct request_sock *req, **prev;
429 case TCP_LISTEN:
430 if (sock_owned_by_user(sk))
431 goto out;
432
433 req = inet_csk_search_req(sk, &prev, th->dest,
434 iph->daddr, iph->saddr);
435 if (!req)
436 goto out;
437
438 /* ICMPs are not backlogged, hence we cannot get
439 an established socket here.
440 */
441 BUG_TRAP(!req->sk);
442
443 if (seq != tcp_rsk(req)->snt_isn) {
444 NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
445 goto out;
446 }
447
448 /*
449 * Still in SYN_RECV, just remove it silently.
450 * There is no good way to pass the error to the newly
451 * created socket, and POSIX does not want network
452 * errors returned from accept().
453 */
454 inet_csk_reqsk_queue_drop(sk, req, prev);
455 goto out;
456
457 case TCP_SYN_SENT:
458 case TCP_SYN_RECV: /* Cannot happen.
459 It can f.e. if SYNs crossed.
460 */
461 if (!sock_owned_by_user(sk)) {
462 sk->sk_err = err;
463
464 sk->sk_error_report(sk);
465
466 tcp_done(sk);
467 } else {
468 sk->sk_err_soft = err;
469 }
470 goto out;
471 }
472
473 /* If we've already connected we will keep trying
474 * until we time out, or the user gives up.
475 *
476 * rfc1122 4.2.3.9 allows to consider as hard errors
477 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
478 * but it is obsoleted by pmtu discovery).
479 *
480 * Note, that in modern internet, where routing is unreliable
481 * and in each dark corner broken firewalls sit, sending random
482 * errors ordered by their masters even this two messages finally lose
483 * their original sense (even Linux sends invalid PORT_UNREACHs)
484 *
485 * Now we are in compliance with RFCs.
486 * --ANK (980905)
487 */
488
489 inet = inet_sk(sk);
490 if (!sock_owned_by_user(sk) && inet->recverr) {
491 sk->sk_err = err;
492 sk->sk_error_report(sk);
493 } else { /* Only an error on timeout */
494 sk->sk_err_soft = err;
495 }
496
497 out:
498 bh_unlock_sock(sk);
499 sock_put(sk);
500 }
501
502 /* This routine computes an IPv4 TCP checksum. */
503 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
504 {
505 struct inet_sock *inet = inet_sk(sk);
506 struct tcphdr *th = tcp_hdr(skb);
507
508 if (skb->ip_summed == CHECKSUM_PARTIAL) {
509 th->check = ~tcp_v4_check(len, inet->saddr,
510 inet->daddr, 0);
511 skb->csum_start = skb_transport_header(skb) - skb->head;
512 skb->csum_offset = offsetof(struct tcphdr, check);
513 } else {
514 th->check = tcp_v4_check(len, inet->saddr, inet->daddr,
515 csum_partial((char *)th,
516 th->doff << 2,
517 skb->csum));
518 }
519 }
520
521 int tcp_v4_gso_send_check(struct sk_buff *skb)
522 {
523 const struct iphdr *iph;
524 struct tcphdr *th;
525
526 if (!pskb_may_pull(skb, sizeof(*th)))
527 return -EINVAL;
528
529 iph = ip_hdr(skb);
530 th = tcp_hdr(skb);
531
532 th->check = 0;
533 th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0);
534 skb->csum_start = skb_transport_header(skb) - skb->head;
535 skb->csum_offset = offsetof(struct tcphdr, check);
536 skb->ip_summed = CHECKSUM_PARTIAL;
537 return 0;
538 }
539
540 /*
541 * This routine will send an RST to the other tcp.
542 *
543 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
544 * for reset.
545 * Answer: if a packet caused RST, it is not for a socket
546 * existing in our system, if it is matched to a socket,
547 * it is just duplicate segment or bug in other side's TCP.
548 * So that we build reply only basing on parameters
549 * arrived with segment.
550 * Exception: precedence violation. We do not implement it in any case.
551 */
552
553 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
554 {
555 struct tcphdr *th = tcp_hdr(skb);
556 struct {
557 struct tcphdr th;
558 #ifdef CONFIG_TCP_MD5SIG
559 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
560 #endif
561 } rep;
562 struct ip_reply_arg arg;
563 #ifdef CONFIG_TCP_MD5SIG
564 struct tcp_md5sig_key *key;
565 #endif
566
567 /* Never send a reset in response to a reset. */
568 if (th->rst)
569 return;
570
571 if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL)
572 return;
573
574 /* Swap the send and the receive. */
575 memset(&rep, 0, sizeof(rep));
576 rep.th.dest = th->source;
577 rep.th.source = th->dest;
578 rep.th.doff = sizeof(struct tcphdr) / 4;
579 rep.th.rst = 1;
580
581 if (th->ack) {
582 rep.th.seq = th->ack_seq;
583 } else {
584 rep.th.ack = 1;
585 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
586 skb->len - (th->doff << 2));
587 }
588
589 memset(&arg, 0, sizeof(arg));
590 arg.iov[0].iov_base = (unsigned char *)&rep;
591 arg.iov[0].iov_len = sizeof(rep.th);
592
593 #ifdef CONFIG_TCP_MD5SIG
594 key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
595 if (key) {
596 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
597 (TCPOPT_NOP << 16) |
598 (TCPOPT_MD5SIG << 8) |
599 TCPOLEN_MD5SIG);
600 /* Update length and the length the header thinks exists */
601 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
602 rep.th.doff = arg.iov[0].iov_len / 4;
603
604 tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[1],
605 key,
606 ip_hdr(skb)->daddr,
607 ip_hdr(skb)->saddr,
608 &rep.th, IPPROTO_TCP,
609 arg.iov[0].iov_len);
610 }
611 #endif
612 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
613 ip_hdr(skb)->saddr, /* XXX */
614 sizeof(struct tcphdr), IPPROTO_TCP, 0);
615 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
616
617 ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
618
619 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
620 TCP_INC_STATS_BH(TCP_MIB_OUTRSTS);
621 }
622
623 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
624 outside socket context is ugly, certainly. What can I do?
625 */
626
627 static void tcp_v4_send_ack(struct tcp_timewait_sock *twsk,
628 struct sk_buff *skb, u32 seq, u32 ack,
629 u32 win, u32 ts)
630 {
631 struct tcphdr *th = tcp_hdr(skb);
632 struct {
633 struct tcphdr th;
634 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
635 #ifdef CONFIG_TCP_MD5SIG
636 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
637 #endif
638 ];
639 } rep;
640 struct ip_reply_arg arg;
641 #ifdef CONFIG_TCP_MD5SIG
642 struct tcp_md5sig_key *key;
643 struct tcp_md5sig_key tw_key;
644 #endif
645
646 memset(&rep.th, 0, sizeof(struct tcphdr));
647 memset(&arg, 0, sizeof(arg));
648
649 arg.iov[0].iov_base = (unsigned char *)&rep;
650 arg.iov[0].iov_len = sizeof(rep.th);
651 if (ts) {
652 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
653 (TCPOPT_TIMESTAMP << 8) |
654 TCPOLEN_TIMESTAMP);
655 rep.opt[1] = htonl(tcp_time_stamp);
656 rep.opt[2] = htonl(ts);
657 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
658 }
659
660 /* Swap the send and the receive. */
661 rep.th.dest = th->source;
662 rep.th.source = th->dest;
663 rep.th.doff = arg.iov[0].iov_len / 4;
664 rep.th.seq = htonl(seq);
665 rep.th.ack_seq = htonl(ack);
666 rep.th.ack = 1;
667 rep.th.window = htons(win);
668
669 #ifdef CONFIG_TCP_MD5SIG
670 /*
671 * The SKB holds an imcoming packet, but may not have a valid ->sk
672 * pointer. This is especially the case when we're dealing with a
673 * TIME_WAIT ack, because the sk structure is long gone, and only
674 * the tcp_timewait_sock remains. So the md5 key is stashed in that
675 * structure, and we use it in preference. I believe that (twsk ||
676 * skb->sk) holds true, but we program defensively.
677 */
678 if (!twsk && skb->sk) {
679 key = tcp_v4_md5_do_lookup(skb->sk, ip_hdr(skb)->daddr);
680 } else if (twsk && twsk->tw_md5_keylen) {
681 tw_key.key = twsk->tw_md5_key;
682 tw_key.keylen = twsk->tw_md5_keylen;
683 key = &tw_key;
684 } else
685 key = NULL;
686
687 if (key) {
688 int offset = (ts) ? 3 : 0;
689
690 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
691 (TCPOPT_NOP << 16) |
692 (TCPOPT_MD5SIG << 8) |
693 TCPOLEN_MD5SIG);
694 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
695 rep.th.doff = arg.iov[0].iov_len/4;
696
697 tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[offset],
698 key,
699 ip_hdr(skb)->daddr,
700 ip_hdr(skb)->saddr,
701 &rep.th, IPPROTO_TCP,
702 arg.iov[0].iov_len);
703 }
704 #endif
705 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
706 ip_hdr(skb)->saddr, /* XXX */
707 arg.iov[0].iov_len, IPPROTO_TCP, 0);
708 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
709 if (twsk)
710 arg.bound_dev_if = twsk->tw_sk.tw_bound_dev_if;
711
712 ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
713
714 TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
715 }
716
717 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
718 {
719 struct inet_timewait_sock *tw = inet_twsk(sk);
720 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
721
722 tcp_v4_send_ack(tcptw, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
723 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
724 tcptw->tw_ts_recent);
725
726 inet_twsk_put(tw);
727 }
728
729 static void tcp_v4_reqsk_send_ack(struct sk_buff *skb,
730 struct request_sock *req)
731 {
732 tcp_v4_send_ack(NULL, skb, tcp_rsk(req)->snt_isn + 1,
733 tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
734 req->ts_recent);
735 }
736
737 /*
738 * Send a SYN-ACK after having received an ACK.
739 * This still operates on a request_sock only, not on a big
740 * socket.
741 */
742 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
743 struct dst_entry *dst)
744 {
745 const struct inet_request_sock *ireq = inet_rsk(req);
746 int err = -1;
747 struct sk_buff * skb;
748
749 /* First, grab a route. */
750 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
751 goto out;
752
753 skb = tcp_make_synack(sk, dst, req);
754
755 if (skb) {
756 struct tcphdr *th = tcp_hdr(skb);
757
758 th->check = tcp_v4_check(skb->len,
759 ireq->loc_addr,
760 ireq->rmt_addr,
761 csum_partial((char *)th, skb->len,
762 skb->csum));
763
764 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
765 ireq->rmt_addr,
766 ireq->opt);
767 err = net_xmit_eval(err);
768 }
769
770 out:
771 dst_release(dst);
772 return err;
773 }
774
775 /*
776 * IPv4 request_sock destructor.
777 */
778 static void tcp_v4_reqsk_destructor(struct request_sock *req)
779 {
780 kfree(inet_rsk(req)->opt);
781 }
782
783 #ifdef CONFIG_SYN_COOKIES
784 static void syn_flood_warning(struct sk_buff *skb)
785 {
786 static unsigned long warntime;
787
788 if (time_after(jiffies, (warntime + HZ * 60))) {
789 warntime = jiffies;
790 printk(KERN_INFO
791 "possible SYN flooding on port %d. Sending cookies.\n",
792 ntohs(tcp_hdr(skb)->dest));
793 }
794 }
795 #endif
796
797 /*
798 * Save and compile IPv4 options into the request_sock if needed.
799 */
800 static struct ip_options *tcp_v4_save_options(struct sock *sk,
801 struct sk_buff *skb)
802 {
803 struct ip_options *opt = &(IPCB(skb)->opt);
804 struct ip_options *dopt = NULL;
805
806 if (opt && opt->optlen) {
807 int opt_size = optlength(opt);
808 dopt = kmalloc(opt_size, GFP_ATOMIC);
809 if (dopt) {
810 if (ip_options_echo(dopt, skb)) {
811 kfree(dopt);
812 dopt = NULL;
813 }
814 }
815 }
816 return dopt;
817 }
818
819 #ifdef CONFIG_TCP_MD5SIG
820 /*
821 * RFC2385 MD5 checksumming requires a mapping of
822 * IP address->MD5 Key.
823 * We need to maintain these in the sk structure.
824 */
825
826 /* Find the Key structure for an address. */
827 static struct tcp_md5sig_key *
828 tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
829 {
830 struct tcp_sock *tp = tcp_sk(sk);
831 int i;
832
833 if (!tp->md5sig_info || !tp->md5sig_info->entries4)
834 return NULL;
835 for (i = 0; i < tp->md5sig_info->entries4; i++) {
836 if (tp->md5sig_info->keys4[i].addr == addr)
837 return &tp->md5sig_info->keys4[i].base;
838 }
839 return NULL;
840 }
841
842 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
843 struct sock *addr_sk)
844 {
845 return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->daddr);
846 }
847
848 EXPORT_SYMBOL(tcp_v4_md5_lookup);
849
850 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
851 struct request_sock *req)
852 {
853 return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
854 }
855
856 /* This can be called on a newly created socket, from other files */
857 int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
858 u8 *newkey, u8 newkeylen)
859 {
860 /* Add Key to the list */
861 struct tcp_md5sig_key *key;
862 struct tcp_sock *tp = tcp_sk(sk);
863 struct tcp4_md5sig_key *keys;
864
865 key = tcp_v4_md5_do_lookup(sk, addr);
866 if (key) {
867 /* Pre-existing entry - just update that one. */
868 kfree(key->key);
869 key->key = newkey;
870 key->keylen = newkeylen;
871 } else {
872 struct tcp_md5sig_info *md5sig;
873
874 if (!tp->md5sig_info) {
875 tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
876 GFP_ATOMIC);
877 if (!tp->md5sig_info) {
878 kfree(newkey);
879 return -ENOMEM;
880 }
881 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
882 }
883 if (tcp_alloc_md5sig_pool() == NULL) {
884 kfree(newkey);
885 return -ENOMEM;
886 }
887 md5sig = tp->md5sig_info;
888
889 if (md5sig->alloced4 == md5sig->entries4) {
890 keys = kmalloc((sizeof(*keys) *
891 (md5sig->entries4 + 1)), GFP_ATOMIC);
892 if (!keys) {
893 kfree(newkey);
894 tcp_free_md5sig_pool();
895 return -ENOMEM;
896 }
897
898 if (md5sig->entries4)
899 memcpy(keys, md5sig->keys4,
900 sizeof(*keys) * md5sig->entries4);
901
902 /* Free old key list, and reference new one */
903 kfree(md5sig->keys4);
904 md5sig->keys4 = keys;
905 md5sig->alloced4++;
906 }
907 md5sig->entries4++;
908 md5sig->keys4[md5sig->entries4 - 1].addr = addr;
909 md5sig->keys4[md5sig->entries4 - 1].base.key = newkey;
910 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
911 }
912 return 0;
913 }
914
915 EXPORT_SYMBOL(tcp_v4_md5_do_add);
916
917 static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
918 u8 *newkey, u8 newkeylen)
919 {
920 return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->daddr,
921 newkey, newkeylen);
922 }
923
924 int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
925 {
926 struct tcp_sock *tp = tcp_sk(sk);
927 int i;
928
929 for (i = 0; i < tp->md5sig_info->entries4; i++) {
930 if (tp->md5sig_info->keys4[i].addr == addr) {
931 /* Free the key */
932 kfree(tp->md5sig_info->keys4[i].base.key);
933 tp->md5sig_info->entries4--;
934
935 if (tp->md5sig_info->entries4 == 0) {
936 kfree(tp->md5sig_info->keys4);
937 tp->md5sig_info->keys4 = NULL;
938 tp->md5sig_info->alloced4 = 0;
939 } else if (tp->md5sig_info->entries4 != i) {
940 /* Need to do some manipulation */
941 memmove(&tp->md5sig_info->keys4[i],
942 &tp->md5sig_info->keys4[i+1],
943 (tp->md5sig_info->entries4 - i) *
944 sizeof(struct tcp4_md5sig_key));
945 }
946 tcp_free_md5sig_pool();
947 return 0;
948 }
949 }
950 return -ENOENT;
951 }
952
953 EXPORT_SYMBOL(tcp_v4_md5_do_del);
954
955 static void tcp_v4_clear_md5_list(struct sock *sk)
956 {
957 struct tcp_sock *tp = tcp_sk(sk);
958
959 /* Free each key, then the set of key keys,
960 * the crypto element, and then decrement our
961 * hold on the last resort crypto.
962 */
963 if (tp->md5sig_info->entries4) {
964 int i;
965 for (i = 0; i < tp->md5sig_info->entries4; i++)
966 kfree(tp->md5sig_info->keys4[i].base.key);
967 tp->md5sig_info->entries4 = 0;
968 tcp_free_md5sig_pool();
969 }
970 if (tp->md5sig_info->keys4) {
971 kfree(tp->md5sig_info->keys4);
972 tp->md5sig_info->keys4 = NULL;
973 tp->md5sig_info->alloced4 = 0;
974 }
975 }
976
977 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
978 int optlen)
979 {
980 struct tcp_md5sig cmd;
981 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
982 u8 *newkey;
983
984 if (optlen < sizeof(cmd))
985 return -EINVAL;
986
987 if (copy_from_user(&cmd, optval, sizeof(cmd)))
988 return -EFAULT;
989
990 if (sin->sin_family != AF_INET)
991 return -EINVAL;
992
993 if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
994 if (!tcp_sk(sk)->md5sig_info)
995 return -ENOENT;
996 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
997 }
998
999 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1000 return -EINVAL;
1001
1002 if (!tcp_sk(sk)->md5sig_info) {
1003 struct tcp_sock *tp = tcp_sk(sk);
1004 struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL);
1005
1006 if (!p)
1007 return -EINVAL;
1008
1009 tp->md5sig_info = p;
1010 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1011 }
1012
1013 newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
1014 if (!newkey)
1015 return -ENOMEM;
1016 return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
1017 newkey, cmd.tcpm_keylen);
1018 }
1019
1020 static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
1021 __be32 saddr, __be32 daddr,
1022 struct tcphdr *th, int protocol,
1023 int tcplen)
1024 {
1025 struct scatterlist sg[4];
1026 __u16 data_len;
1027 int block = 0;
1028 __sum16 old_checksum;
1029 struct tcp_md5sig_pool *hp;
1030 struct tcp4_pseudohdr *bp;
1031 struct hash_desc *desc;
1032 int err;
1033 unsigned int nbytes = 0;
1034
1035 /*
1036 * Okay, so RFC2385 is turned on for this connection,
1037 * so we need to generate the MD5 hash for the packet now.
1038 */
1039
1040 hp = tcp_get_md5sig_pool();
1041 if (!hp)
1042 goto clear_hash_noput;
1043
1044 bp = &hp->md5_blk.ip4;
1045 desc = &hp->md5_desc;
1046
1047 /*
1048 * 1. the TCP pseudo-header (in the order: source IP address,
1049 * destination IP address, zero-padded protocol number, and
1050 * segment length)
1051 */
1052 bp->saddr = saddr;
1053 bp->daddr = daddr;
1054 bp->pad = 0;
1055 bp->protocol = protocol;
1056 bp->len = htons(tcplen);
1057
1058 sg_init_table(sg, 4);
1059
1060 sg_set_buf(&sg[block++], bp, sizeof(*bp));
1061 nbytes += sizeof(*bp);
1062
1063 /* 2. the TCP header, excluding options, and assuming a
1064 * checksum of zero/
1065 */
1066 old_checksum = th->check;
1067 th->check = 0;
1068 sg_set_buf(&sg[block++], th, sizeof(struct tcphdr));
1069 nbytes += sizeof(struct tcphdr);
1070
1071 /* 3. the TCP segment data (if any) */
1072 data_len = tcplen - (th->doff << 2);
1073 if (data_len > 0) {
1074 unsigned char *data = (unsigned char *)th + (th->doff << 2);
1075 sg_set_buf(&sg[block++], data, data_len);
1076 nbytes += data_len;
1077 }
1078
1079 /* 4. an independently-specified key or password, known to both
1080 * TCPs and presumably connection-specific
1081 */
1082 sg_set_buf(&sg[block++], key->key, key->keylen);
1083 nbytes += key->keylen;
1084
1085 sg_mark_end(&sg[block - 1]);
1086
1087 /* Now store the Hash into the packet */
1088 err = crypto_hash_init(desc);
1089 if (err)
1090 goto clear_hash;
1091 err = crypto_hash_update(desc, sg, nbytes);
1092 if (err)
1093 goto clear_hash;
1094 err = crypto_hash_final(desc, md5_hash);
1095 if (err)
1096 goto clear_hash;
1097
1098 /* Reset header, and free up the crypto */
1099 tcp_put_md5sig_pool();
1100 th->check = old_checksum;
1101
1102 out:
1103 return 0;
1104 clear_hash:
1105 tcp_put_md5sig_pool();
1106 clear_hash_noput:
1107 memset(md5_hash, 0, 16);
1108 goto out;
1109 }
1110
1111 int tcp_v4_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
1112 struct sock *sk,
1113 struct dst_entry *dst,
1114 struct request_sock *req,
1115 struct tcphdr *th, int protocol,
1116 int tcplen)
1117 {
1118 __be32 saddr, daddr;
1119
1120 if (sk) {
1121 saddr = inet_sk(sk)->saddr;
1122 daddr = inet_sk(sk)->daddr;
1123 } else {
1124 struct rtable *rt = (struct rtable *)dst;
1125 BUG_ON(!rt);
1126 saddr = rt->rt_src;
1127 daddr = rt->rt_dst;
1128 }
1129 return tcp_v4_do_calc_md5_hash(md5_hash, key,
1130 saddr, daddr,
1131 th, protocol, tcplen);
1132 }
1133
1134 EXPORT_SYMBOL(tcp_v4_calc_md5_hash);
1135
1136 static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1137 {
1138 /*
1139 * This gets called for each TCP segment that arrives
1140 * so we want to be efficient.
1141 * We have 3 drop cases:
1142 * o No MD5 hash and one expected.
1143 * o MD5 hash and we're not expecting one.
1144 * o MD5 hash and its wrong.
1145 */
1146 __u8 *hash_location = NULL;
1147 struct tcp_md5sig_key *hash_expected;
1148 const struct iphdr *iph = ip_hdr(skb);
1149 struct tcphdr *th = tcp_hdr(skb);
1150 int length = (th->doff << 2) - sizeof(struct tcphdr);
1151 int genhash;
1152 unsigned char *ptr;
1153 unsigned char newhash[16];
1154
1155 hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1156
1157 /*
1158 * If the TCP option length is less than the TCP_MD5SIG
1159 * option length, then we can shortcut
1160 */
1161 if (length < TCPOLEN_MD5SIG) {
1162 if (hash_expected)
1163 return 1;
1164 else
1165 return 0;
1166 }
1167
1168 /* Okay, we can't shortcut - we have to grub through the options */
1169 ptr = (unsigned char *)(th + 1);
1170 while (length > 0) {
1171 int opcode = *ptr++;
1172 int opsize;
1173
1174 switch (opcode) {
1175 case TCPOPT_EOL:
1176 goto done_opts;
1177 case TCPOPT_NOP:
1178 length--;
1179 continue;
1180 default:
1181 opsize = *ptr++;
1182 if (opsize < 2)
1183 goto done_opts;
1184 if (opsize > length)
1185 goto done_opts;
1186
1187 if (opcode == TCPOPT_MD5SIG) {
1188 hash_location = ptr;
1189 goto done_opts;
1190 }
1191 }
1192 ptr += opsize-2;
1193 length -= opsize;
1194 }
1195 done_opts:
1196 /* We've parsed the options - do we have a hash? */
1197 if (!hash_expected && !hash_location)
1198 return 0;
1199
1200 if (hash_expected && !hash_location) {
1201 LIMIT_NETDEBUG(KERN_INFO "MD5 Hash expected but NOT found "
1202 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1203 NIPQUAD(iph->saddr), ntohs(th->source),
1204 NIPQUAD(iph->daddr), ntohs(th->dest));
1205 return 1;
1206 }
1207
1208 if (!hash_expected && hash_location) {
1209 LIMIT_NETDEBUG(KERN_INFO "MD5 Hash NOT expected but found "
1210 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1211 NIPQUAD(iph->saddr), ntohs(th->source),
1212 NIPQUAD(iph->daddr), ntohs(th->dest));
1213 return 1;
1214 }
1215
1216 /* Okay, so this is hash_expected and hash_location -
1217 * so we need to calculate the checksum.
1218 */
1219 genhash = tcp_v4_do_calc_md5_hash(newhash,
1220 hash_expected,
1221 iph->saddr, iph->daddr,
1222 th, sk->sk_protocol,
1223 skb->len);
1224
1225 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1226 if (net_ratelimit()) {
1227 printk(KERN_INFO "MD5 Hash failed for "
1228 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)%s\n",
1229 NIPQUAD(iph->saddr), ntohs(th->source),
1230 NIPQUAD(iph->daddr), ntohs(th->dest),
1231 genhash ? " tcp_v4_calc_md5_hash failed" : "");
1232 }
1233 return 1;
1234 }
1235 return 0;
1236 }
1237
1238 #endif
1239
1240 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1241 .family = PF_INET,
1242 .obj_size = sizeof(struct tcp_request_sock),
1243 .rtx_syn_ack = tcp_v4_send_synack,
1244 .send_ack = tcp_v4_reqsk_send_ack,
1245 .destructor = tcp_v4_reqsk_destructor,
1246 .send_reset = tcp_v4_send_reset,
1247 };
1248
1249 #ifdef CONFIG_TCP_MD5SIG
1250 static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1251 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1252 };
1253 #endif
1254
1255 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1256 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1257 .twsk_unique = tcp_twsk_unique,
1258 .twsk_destructor= tcp_twsk_destructor,
1259 };
1260
1261 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1262 {
1263 struct inet_request_sock *ireq;
1264 struct tcp_options_received tmp_opt;
1265 struct request_sock *req;
1266 __be32 saddr = ip_hdr(skb)->saddr;
1267 __be32 daddr = ip_hdr(skb)->daddr;
1268 __u32 isn = TCP_SKB_CB(skb)->when;
1269 struct dst_entry *dst = NULL;
1270 #ifdef CONFIG_SYN_COOKIES
1271 int want_cookie = 0;
1272 #else
1273 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
1274 #endif
1275
1276 /* Never answer to SYNs send to broadcast or multicast */
1277 if (((struct rtable *)skb->dst)->rt_flags &
1278 (RTCF_BROADCAST | RTCF_MULTICAST))
1279 goto drop;
1280
1281 /* TW buckets are converted to open requests without
1282 * limitations, they conserve resources and peer is
1283 * evidently real one.
1284 */
1285 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1286 #ifdef CONFIG_SYN_COOKIES
1287 if (sysctl_tcp_syncookies) {
1288 want_cookie = 1;
1289 } else
1290 #endif
1291 goto drop;
1292 }
1293
1294 /* Accept backlog is full. If we have already queued enough
1295 * of warm entries in syn queue, drop request. It is better than
1296 * clogging syn queue with openreqs with exponentially increasing
1297 * timeout.
1298 */
1299 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1300 goto drop;
1301
1302 req = reqsk_alloc(&tcp_request_sock_ops);
1303 if (!req)
1304 goto drop;
1305
1306 #ifdef CONFIG_TCP_MD5SIG
1307 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1308 #endif
1309
1310 tcp_clear_options(&tmp_opt);
1311 tmp_opt.mss_clamp = 536;
1312 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
1313
1314 tcp_parse_options(skb, &tmp_opt, 0);
1315
1316 if (want_cookie) {
1317 tcp_clear_options(&tmp_opt);
1318 tmp_opt.saw_tstamp = 0;
1319 }
1320
1321 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
1322 /* Some OSes (unknown ones, but I see them on web server, which
1323 * contains information interesting only for windows'
1324 * users) do not send their stamp in SYN. It is easy case.
1325 * We simply do not advertise TS support.
1326 */
1327 tmp_opt.saw_tstamp = 0;
1328 tmp_opt.tstamp_ok = 0;
1329 }
1330 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1331
1332 tcp_openreq_init(req, &tmp_opt, skb);
1333
1334 if (security_inet_conn_request(sk, skb, req))
1335 goto drop_and_free;
1336
1337 ireq = inet_rsk(req);
1338 ireq->loc_addr = daddr;
1339 ireq->rmt_addr = saddr;
1340 ireq->opt = tcp_v4_save_options(sk, skb);
1341 if (!want_cookie)
1342 TCP_ECN_create_request(req, tcp_hdr(skb));
1343
1344 if (want_cookie) {
1345 #ifdef CONFIG_SYN_COOKIES
1346 syn_flood_warning(skb);
1347 #endif
1348 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1349 } else if (!isn) {
1350 struct inet_peer *peer = NULL;
1351
1352 /* VJ's idea. We save last timestamp seen
1353 * from the destination in peer table, when entering
1354 * state TIME-WAIT, and check against it before
1355 * accepting new connection request.
1356 *
1357 * If "isn" is not zero, this request hit alive
1358 * timewait bucket, so that all the necessary checks
1359 * are made in the function processing timewait state.
1360 */
1361 if (tmp_opt.saw_tstamp &&
1362 tcp_death_row.sysctl_tw_recycle &&
1363 (dst = inet_csk_route_req(sk, req)) != NULL &&
1364 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1365 peer->v4daddr == saddr) {
1366 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1367 (s32)(peer->tcp_ts - req->ts_recent) >
1368 TCP_PAWS_WINDOW) {
1369 NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED);
1370 dst_release(dst);
1371 goto drop_and_free;
1372 }
1373 }
1374 /* Kill the following clause, if you dislike this way. */
1375 else if (!sysctl_tcp_syncookies &&
1376 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1377 (sysctl_max_syn_backlog >> 2)) &&
1378 (!peer || !peer->tcp_ts_stamp) &&
1379 (!dst || !dst_metric(dst, RTAX_RTT))) {
1380 /* Without syncookies last quarter of
1381 * backlog is filled with destinations,
1382 * proven to be alive.
1383 * It means that we continue to communicate
1384 * to destinations, already remembered
1385 * to the moment of synflood.
1386 */
1387 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
1388 "request from %u.%u.%u.%u/%u\n",
1389 NIPQUAD(saddr),
1390 ntohs(tcp_hdr(skb)->source));
1391 dst_release(dst);
1392 goto drop_and_free;
1393 }
1394
1395 isn = tcp_v4_init_sequence(skb);
1396 }
1397 tcp_rsk(req)->snt_isn = isn;
1398
1399 if (tcp_v4_send_synack(sk, req, dst))
1400 goto drop_and_free;
1401
1402 if (want_cookie) {
1403 reqsk_free(req);
1404 } else {
1405 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1406 }
1407 return 0;
1408
1409 drop_and_free:
1410 reqsk_free(req);
1411 drop:
1412 return 0;
1413 }
1414
1415
1416 /*
1417 * The three way handshake has completed - we got a valid synack -
1418 * now create the new socket.
1419 */
1420 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1421 struct request_sock *req,
1422 struct dst_entry *dst)
1423 {
1424 struct inet_request_sock *ireq;
1425 struct inet_sock *newinet;
1426 struct tcp_sock *newtp;
1427 struct sock *newsk;
1428 #ifdef CONFIG_TCP_MD5SIG
1429 struct tcp_md5sig_key *key;
1430 #endif
1431
1432 if (sk_acceptq_is_full(sk))
1433 goto exit_overflow;
1434
1435 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1436 goto exit;
1437
1438 newsk = tcp_create_openreq_child(sk, req, skb);
1439 if (!newsk)
1440 goto exit;
1441
1442 newsk->sk_gso_type = SKB_GSO_TCPV4;
1443 sk_setup_caps(newsk, dst);
1444
1445 newtp = tcp_sk(newsk);
1446 newinet = inet_sk(newsk);
1447 ireq = inet_rsk(req);
1448 newinet->daddr = ireq->rmt_addr;
1449 newinet->rcv_saddr = ireq->loc_addr;
1450 newinet->saddr = ireq->loc_addr;
1451 newinet->opt = ireq->opt;
1452 ireq->opt = NULL;
1453 newinet->mc_index = inet_iif(skb);
1454 newinet->mc_ttl = ip_hdr(skb)->ttl;
1455 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1456 if (newinet->opt)
1457 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1458 newinet->id = newtp->write_seq ^ jiffies;
1459
1460 tcp_mtup_init(newsk);
1461 tcp_sync_mss(newsk, dst_mtu(dst));
1462 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1463 tcp_initialize_rcv_mss(newsk);
1464
1465 #ifdef CONFIG_TCP_MD5SIG
1466 /* Copy over the MD5 key from the original socket */
1467 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
1468 /*
1469 * We're using one, so create a matching key
1470 * on the newsk structure. If we fail to get
1471 * memory, then we end up not copying the key
1472 * across. Shucks.
1473 */
1474 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1475 if (newkey != NULL)
1476 tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
1477 newkey, key->keylen);
1478 }
1479 #endif
1480
1481 __inet_hash(&tcp_hashinfo, newsk, 0);
1482 __inet_inherit_port(&tcp_hashinfo, sk, newsk);
1483
1484 return newsk;
1485
1486 exit_overflow:
1487 NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
1488 exit:
1489 NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
1490 dst_release(dst);
1491 return NULL;
1492 }
1493
1494 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1495 {
1496 struct tcphdr *th = tcp_hdr(skb);
1497 const struct iphdr *iph = ip_hdr(skb);
1498 struct sock *nsk;
1499 struct request_sock **prev;
1500 /* Find possible connection requests. */
1501 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1502 iph->saddr, iph->daddr);
1503 if (req)
1504 return tcp_check_req(sk, skb, req, prev);
1505
1506 nsk = inet_lookup_established(&tcp_hashinfo, iph->saddr, th->source,
1507 iph->daddr, th->dest, inet_iif(skb));
1508
1509 if (nsk) {
1510 if (nsk->sk_state != TCP_TIME_WAIT) {
1511 bh_lock_sock(nsk);
1512 return nsk;
1513 }
1514 inet_twsk_put(inet_twsk(nsk));
1515 return NULL;
1516 }
1517
1518 #ifdef CONFIG_SYN_COOKIES
1519 if (!th->rst && !th->syn && th->ack)
1520 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1521 #endif
1522 return sk;
1523 }
1524
1525 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1526 {
1527 const struct iphdr *iph = ip_hdr(skb);
1528
1529 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1530 if (!tcp_v4_check(skb->len, iph->saddr,
1531 iph->daddr, skb->csum)) {
1532 skb->ip_summed = CHECKSUM_UNNECESSARY;
1533 return 0;
1534 }
1535 }
1536
1537 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1538 skb->len, IPPROTO_TCP, 0);
1539
1540 if (skb->len <= 76) {
1541 return __skb_checksum_complete(skb);
1542 }
1543 return 0;
1544 }
1545
1546
1547 /* The socket must have it's spinlock held when we get
1548 * here.
1549 *
1550 * We have a potential double-lock case here, so even when
1551 * doing backlog processing we use the BH locking scheme.
1552 * This is because we cannot sleep with the original spinlock
1553 * held.
1554 */
1555 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1556 {
1557 struct sock *rsk;
1558 #ifdef CONFIG_TCP_MD5SIG
1559 /*
1560 * We really want to reject the packet as early as possible
1561 * if:
1562 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1563 * o There is an MD5 option and we're not expecting one
1564 */
1565 if (tcp_v4_inbound_md5_hash(sk, skb))
1566 goto discard;
1567 #endif
1568
1569 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1570 TCP_CHECK_TIMER(sk);
1571 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1572 rsk = sk;
1573 goto reset;
1574 }
1575 TCP_CHECK_TIMER(sk);
1576 return 0;
1577 }
1578
1579 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1580 goto csum_err;
1581
1582 if (sk->sk_state == TCP_LISTEN) {
1583 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1584 if (!nsk)
1585 goto discard;
1586
1587 if (nsk != sk) {
1588 if (tcp_child_process(sk, nsk, skb)) {
1589 rsk = nsk;
1590 goto reset;
1591 }
1592 return 0;
1593 }
1594 }
1595
1596 TCP_CHECK_TIMER(sk);
1597 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1598 rsk = sk;
1599 goto reset;
1600 }
1601 TCP_CHECK_TIMER(sk);
1602 return 0;
1603
1604 reset:
1605 tcp_v4_send_reset(rsk, skb);
1606 discard:
1607 kfree_skb(skb);
1608 /* Be careful here. If this function gets more complicated and
1609 * gcc suffers from register pressure on the x86, sk (in %ebx)
1610 * might be destroyed here. This current version compiles correctly,
1611 * but you have been warned.
1612 */
1613 return 0;
1614
1615 csum_err:
1616 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1617 goto discard;
1618 }
1619
1620 /*
1621 * From tcp_input.c
1622 */
1623
1624 int tcp_v4_rcv(struct sk_buff *skb)
1625 {
1626 const struct iphdr *iph;
1627 struct tcphdr *th;
1628 struct sock *sk;
1629 int ret;
1630
1631 if (skb->pkt_type != PACKET_HOST)
1632 goto discard_it;
1633
1634 /* Count it even if it's bad */
1635 TCP_INC_STATS_BH(TCP_MIB_INSEGS);
1636
1637 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1638 goto discard_it;
1639
1640 th = tcp_hdr(skb);
1641
1642 if (th->doff < sizeof(struct tcphdr) / 4)
1643 goto bad_packet;
1644 if (!pskb_may_pull(skb, th->doff * 4))
1645 goto discard_it;
1646
1647 /* An explanation is required here, I think.
1648 * Packet length and doff are validated by header prediction,
1649 * provided case of th->doff==0 is eliminated.
1650 * So, we defer the checks. */
1651 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1652 goto bad_packet;
1653
1654 th = tcp_hdr(skb);
1655 iph = ip_hdr(skb);
1656 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1657 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1658 skb->len - th->doff * 4);
1659 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1660 TCP_SKB_CB(skb)->when = 0;
1661 TCP_SKB_CB(skb)->flags = iph->tos;
1662 TCP_SKB_CB(skb)->sacked = 0;
1663
1664 sk = __inet_lookup(&tcp_hashinfo, iph->saddr, th->source,
1665 iph->daddr, th->dest, inet_iif(skb));
1666 if (!sk)
1667 goto no_tcp_socket;
1668
1669 process:
1670 if (sk->sk_state == TCP_TIME_WAIT)
1671 goto do_time_wait;
1672
1673 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1674 goto discard_and_relse;
1675 nf_reset(skb);
1676
1677 if (sk_filter(sk, skb))
1678 goto discard_and_relse;
1679
1680 skb->dev = NULL;
1681
1682 bh_lock_sock_nested(sk);
1683 ret = 0;
1684 if (!sock_owned_by_user(sk)) {
1685 #ifdef CONFIG_NET_DMA
1686 struct tcp_sock *tp = tcp_sk(sk);
1687 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1688 tp->ucopy.dma_chan = get_softnet_dma();
1689 if (tp->ucopy.dma_chan)
1690 ret = tcp_v4_do_rcv(sk, skb);
1691 else
1692 #endif
1693 {
1694 if (!tcp_prequeue(sk, skb))
1695 ret = tcp_v4_do_rcv(sk, skb);
1696 }
1697 } else
1698 sk_add_backlog(sk, skb);
1699 bh_unlock_sock(sk);
1700
1701 sock_put(sk);
1702
1703 return ret;
1704
1705 no_tcp_socket:
1706 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1707 goto discard_it;
1708
1709 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1710 bad_packet:
1711 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1712 } else {
1713 tcp_v4_send_reset(NULL, skb);
1714 }
1715
1716 discard_it:
1717 /* Discard frame. */
1718 kfree_skb(skb);
1719 return 0;
1720
1721 discard_and_relse:
1722 sock_put(sk);
1723 goto discard_it;
1724
1725 do_time_wait:
1726 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1727 inet_twsk_put(inet_twsk(sk));
1728 goto discard_it;
1729 }
1730
1731 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1732 TCP_INC_STATS_BH(TCP_MIB_INERRS);
1733 inet_twsk_put(inet_twsk(sk));
1734 goto discard_it;
1735 }
1736 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1737 case TCP_TW_SYN: {
1738 struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
1739 iph->daddr, th->dest,
1740 inet_iif(skb));
1741 if (sk2) {
1742 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1743 inet_twsk_put(inet_twsk(sk));
1744 sk = sk2;
1745 goto process;
1746 }
1747 /* Fall through to ACK */
1748 }
1749 case TCP_TW_ACK:
1750 tcp_v4_timewait_ack(sk, skb);
1751 break;
1752 case TCP_TW_RST:
1753 goto no_tcp_socket;
1754 case TCP_TW_SUCCESS:;
1755 }
1756 goto discard_it;
1757 }
1758
1759 /* VJ's idea. Save last timestamp seen from this destination
1760 * and hold it at least for normal timewait interval to use for duplicate
1761 * segment detection in subsequent connections, before they enter synchronized
1762 * state.
1763 */
1764
1765 int tcp_v4_remember_stamp(struct sock *sk)
1766 {
1767 struct inet_sock *inet = inet_sk(sk);
1768 struct tcp_sock *tp = tcp_sk(sk);
1769 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1770 struct inet_peer *peer = NULL;
1771 int release_it = 0;
1772
1773 if (!rt || rt->rt_dst != inet->daddr) {
1774 peer = inet_getpeer(inet->daddr, 1);
1775 release_it = 1;
1776 } else {
1777 if (!rt->peer)
1778 rt_bind_peer(rt, 1);
1779 peer = rt->peer;
1780 }
1781
1782 if (peer) {
1783 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1784 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1785 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1786 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1787 peer->tcp_ts = tp->rx_opt.ts_recent;
1788 }
1789 if (release_it)
1790 inet_putpeer(peer);
1791 return 1;
1792 }
1793
1794 return 0;
1795 }
1796
1797 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1798 {
1799 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1800
1801 if (peer) {
1802 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1803
1804 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1805 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1806 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1807 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1808 peer->tcp_ts = tcptw->tw_ts_recent;
1809 }
1810 inet_putpeer(peer);
1811 return 1;
1812 }
1813
1814 return 0;
1815 }
1816
1817 struct inet_connection_sock_af_ops ipv4_specific = {
1818 .queue_xmit = ip_queue_xmit,
1819 .send_check = tcp_v4_send_check,
1820 .rebuild_header = inet_sk_rebuild_header,
1821 .conn_request = tcp_v4_conn_request,
1822 .syn_recv_sock = tcp_v4_syn_recv_sock,
1823 .remember_stamp = tcp_v4_remember_stamp,
1824 .net_header_len = sizeof(struct iphdr),
1825 .setsockopt = ip_setsockopt,
1826 .getsockopt = ip_getsockopt,
1827 .addr2sockaddr = inet_csk_addr2sockaddr,
1828 .sockaddr_len = sizeof(struct sockaddr_in),
1829 #ifdef CONFIG_COMPAT
1830 .compat_setsockopt = compat_ip_setsockopt,
1831 .compat_getsockopt = compat_ip_getsockopt,
1832 #endif
1833 };
1834
1835 #ifdef CONFIG_TCP_MD5SIG
1836 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1837 .md5_lookup = tcp_v4_md5_lookup,
1838 .calc_md5_hash = tcp_v4_calc_md5_hash,
1839 .md5_add = tcp_v4_md5_add_func,
1840 .md5_parse = tcp_v4_parse_md5_keys,
1841 };
1842 #endif
1843
1844 /* NOTE: A lot of things set to zero explicitly by call to
1845 * sk_alloc() so need not be done here.
1846 */
1847 static int tcp_v4_init_sock(struct sock *sk)
1848 {
1849 struct inet_connection_sock *icsk = inet_csk(sk);
1850 struct tcp_sock *tp = tcp_sk(sk);
1851
1852 skb_queue_head_init(&tp->out_of_order_queue);
1853 tcp_init_xmit_timers(sk);
1854 tcp_prequeue_init(tp);
1855
1856 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1857 tp->mdev = TCP_TIMEOUT_INIT;
1858
1859 /* So many TCP implementations out there (incorrectly) count the
1860 * initial SYN frame in their delayed-ACK and congestion control
1861 * algorithms that we must have the following bandaid to talk
1862 * efficiently to them. -DaveM
1863 */
1864 tp->snd_cwnd = 2;
1865
1866 /* See draft-stevens-tcpca-spec-01 for discussion of the
1867 * initialization of these values.
1868 */
1869 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1870 tp->snd_cwnd_clamp = ~0;
1871 tp->mss_cache = 536;
1872
1873 tp->reordering = sysctl_tcp_reordering;
1874 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1875
1876 sk->sk_state = TCP_CLOSE;
1877
1878 sk->sk_write_space = sk_stream_write_space;
1879 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1880
1881 icsk->icsk_af_ops = &ipv4_specific;
1882 icsk->icsk_sync_mss = tcp_sync_mss;
1883 #ifdef CONFIG_TCP_MD5SIG
1884 tp->af_specific = &tcp_sock_ipv4_specific;
1885 #endif
1886
1887 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1888 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1889
1890 atomic_inc(&tcp_sockets_allocated);
1891
1892 return 0;
1893 }
1894
1895 int tcp_v4_destroy_sock(struct sock *sk)
1896 {
1897 struct tcp_sock *tp = tcp_sk(sk);
1898
1899 tcp_clear_xmit_timers(sk);
1900
1901 tcp_cleanup_congestion_control(sk);
1902
1903 /* Cleanup up the write buffer. */
1904 tcp_write_queue_purge(sk);
1905
1906 /* Cleans up our, hopefully empty, out_of_order_queue. */
1907 __skb_queue_purge(&tp->out_of_order_queue);
1908
1909 #ifdef CONFIG_TCP_MD5SIG
1910 /* Clean up the MD5 key list, if any */
1911 if (tp->md5sig_info) {
1912 tcp_v4_clear_md5_list(sk);
1913 kfree(tp->md5sig_info);
1914 tp->md5sig_info = NULL;
1915 }
1916 #endif
1917
1918 #ifdef CONFIG_NET_DMA
1919 /* Cleans up our sk_async_wait_queue */
1920 __skb_queue_purge(&sk->sk_async_wait_queue);
1921 #endif
1922
1923 /* Clean prequeue, it must be empty really */
1924 __skb_queue_purge(&tp->ucopy.prequeue);
1925
1926 /* Clean up a referenced TCP bind bucket. */
1927 if (inet_csk(sk)->icsk_bind_hash)
1928 inet_put_port(&tcp_hashinfo, sk);
1929
1930 /*
1931 * If sendmsg cached page exists, toss it.
1932 */
1933 if (sk->sk_sndmsg_page) {
1934 __free_page(sk->sk_sndmsg_page);
1935 sk->sk_sndmsg_page = NULL;
1936 }
1937
1938 atomic_dec(&tcp_sockets_allocated);
1939
1940 return 0;
1941 }
1942
1943 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1944
1945 #ifdef CONFIG_PROC_FS
1946 /* Proc filesystem TCP sock list dumping. */
1947
1948 static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
1949 {
1950 return hlist_empty(head) ? NULL :
1951 list_entry(head->first, struct inet_timewait_sock, tw_node);
1952 }
1953
1954 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1955 {
1956 return tw->tw_node.next ?
1957 hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1958 }
1959
1960 static void *listening_get_next(struct seq_file *seq, void *cur)
1961 {
1962 struct inet_connection_sock *icsk;
1963 struct hlist_node *node;
1964 struct sock *sk = cur;
1965 struct tcp_iter_state* st = seq->private;
1966
1967 if (!sk) {
1968 st->bucket = 0;
1969 sk = sk_head(&tcp_hashinfo.listening_hash[0]);
1970 goto get_sk;
1971 }
1972
1973 ++st->num;
1974
1975 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1976 struct request_sock *req = cur;
1977
1978 icsk = inet_csk(st->syn_wait_sk);
1979 req = req->dl_next;
1980 while (1) {
1981 while (req) {
1982 if (req->rsk_ops->family == st->family) {
1983 cur = req;
1984 goto out;
1985 }
1986 req = req->dl_next;
1987 }
1988 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1989 break;
1990 get_req:
1991 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1992 }
1993 sk = sk_next(st->syn_wait_sk);
1994 st->state = TCP_SEQ_STATE_LISTENING;
1995 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1996 } else {
1997 icsk = inet_csk(sk);
1998 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1999 if (reqsk_queue_len(&icsk->icsk_accept_queue))
2000 goto start_req;
2001 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2002 sk = sk_next(sk);
2003 }
2004 get_sk:
2005 sk_for_each_from(sk, node) {
2006 if (sk->sk_family == st->family) {
2007 cur = sk;
2008 goto out;
2009 }
2010 icsk = inet_csk(sk);
2011 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2012 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
2013 start_req:
2014 st->uid = sock_i_uid(sk);
2015 st->syn_wait_sk = sk;
2016 st->state = TCP_SEQ_STATE_OPENREQ;
2017 st->sbucket = 0;
2018 goto get_req;
2019 }
2020 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2021 }
2022 if (++st->bucket < INET_LHTABLE_SIZE) {
2023 sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
2024 goto get_sk;
2025 }
2026 cur = NULL;
2027 out:
2028 return cur;
2029 }
2030
2031 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
2032 {
2033 void *rc = listening_get_next(seq, NULL);
2034
2035 while (rc && *pos) {
2036 rc = listening_get_next(seq, rc);
2037 --*pos;
2038 }
2039 return rc;
2040 }
2041
2042 static void *established_get_first(struct seq_file *seq)
2043 {
2044 struct tcp_iter_state* st = seq->private;
2045 void *rc = NULL;
2046
2047 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
2048 struct sock *sk;
2049 struct hlist_node *node;
2050 struct inet_timewait_sock *tw;
2051 rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
2052
2053 read_lock_bh(lock);
2054 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2055 if (sk->sk_family != st->family) {
2056 continue;
2057 }
2058 rc = sk;
2059 goto out;
2060 }
2061 st->state = TCP_SEQ_STATE_TIME_WAIT;
2062 inet_twsk_for_each(tw, node,
2063 &tcp_hashinfo.ehash[st->bucket].twchain) {
2064 if (tw->tw_family != st->family) {
2065 continue;
2066 }
2067 rc = tw;
2068 goto out;
2069 }
2070 read_unlock_bh(lock);
2071 st->state = TCP_SEQ_STATE_ESTABLISHED;
2072 }
2073 out:
2074 return rc;
2075 }
2076
2077 static void *established_get_next(struct seq_file *seq, void *cur)
2078 {
2079 struct sock *sk = cur;
2080 struct inet_timewait_sock *tw;
2081 struct hlist_node *node;
2082 struct tcp_iter_state* st = seq->private;
2083
2084 ++st->num;
2085
2086 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2087 tw = cur;
2088 tw = tw_next(tw);
2089 get_tw:
2090 while (tw && tw->tw_family != st->family) {
2091 tw = tw_next(tw);
2092 }
2093 if (tw) {
2094 cur = tw;
2095 goto out;
2096 }
2097 read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2098 st->state = TCP_SEQ_STATE_ESTABLISHED;
2099
2100 if (++st->bucket < tcp_hashinfo.ehash_size) {
2101 read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2102 sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
2103 } else {
2104 cur = NULL;
2105 goto out;
2106 }
2107 } else
2108 sk = sk_next(sk);
2109
2110 sk_for_each_from(sk, node) {
2111 if (sk->sk_family == st->family)
2112 goto found;
2113 }
2114
2115 st->state = TCP_SEQ_STATE_TIME_WAIT;
2116 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2117 goto get_tw;
2118 found:
2119 cur = sk;
2120 out:
2121 return cur;
2122 }
2123
2124 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2125 {
2126 void *rc = established_get_first(seq);
2127
2128 while (rc && pos) {
2129 rc = established_get_next(seq, rc);
2130 --pos;
2131 }
2132 return rc;
2133 }
2134
2135 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2136 {
2137 void *rc;
2138 struct tcp_iter_state* st = seq->private;
2139
2140 inet_listen_lock(&tcp_hashinfo);
2141 st->state = TCP_SEQ_STATE_LISTENING;
2142 rc = listening_get_idx(seq, &pos);
2143
2144 if (!rc) {
2145 inet_listen_unlock(&tcp_hashinfo);
2146 st->state = TCP_SEQ_STATE_ESTABLISHED;
2147 rc = established_get_idx(seq, pos);
2148 }
2149
2150 return rc;
2151 }
2152
2153 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2154 {
2155 struct tcp_iter_state* st = seq->private;
2156 st->state = TCP_SEQ_STATE_LISTENING;
2157 st->num = 0;
2158 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2159 }
2160
2161 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2162 {
2163 void *rc = NULL;
2164 struct tcp_iter_state* st;
2165
2166 if (v == SEQ_START_TOKEN) {
2167 rc = tcp_get_idx(seq, 0);
2168 goto out;
2169 }
2170 st = seq->private;
2171
2172 switch (st->state) {
2173 case TCP_SEQ_STATE_OPENREQ:
2174 case TCP_SEQ_STATE_LISTENING:
2175 rc = listening_get_next(seq, v);
2176 if (!rc) {
2177 inet_listen_unlock(&tcp_hashinfo);
2178 st->state = TCP_SEQ_STATE_ESTABLISHED;
2179 rc = established_get_first(seq);
2180 }
2181 break;
2182 case TCP_SEQ_STATE_ESTABLISHED:
2183 case TCP_SEQ_STATE_TIME_WAIT:
2184 rc = established_get_next(seq, v);
2185 break;
2186 }
2187 out:
2188 ++*pos;
2189 return rc;
2190 }
2191
2192 static void tcp_seq_stop(struct seq_file *seq, void *v)
2193 {
2194 struct tcp_iter_state* st = seq->private;
2195
2196 switch (st->state) {
2197 case TCP_SEQ_STATE_OPENREQ:
2198 if (v) {
2199 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2200 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2201 }
2202 case TCP_SEQ_STATE_LISTENING:
2203 if (v != SEQ_START_TOKEN)
2204 inet_listen_unlock(&tcp_hashinfo);
2205 break;
2206 case TCP_SEQ_STATE_TIME_WAIT:
2207 case TCP_SEQ_STATE_ESTABLISHED:
2208 if (v)
2209 read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2210 break;
2211 }
2212 }
2213
2214 static int tcp_seq_open(struct inode *inode, struct file *file)
2215 {
2216 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2217 struct seq_file *seq;
2218 struct tcp_iter_state *s;
2219 int rc;
2220
2221 if (unlikely(afinfo == NULL))
2222 return -EINVAL;
2223
2224 s = kzalloc(sizeof(*s), GFP_KERNEL);
2225 if (!s)
2226 return -ENOMEM;
2227 s->family = afinfo->family;
2228 s->seq_ops.start = tcp_seq_start;
2229 s->seq_ops.next = tcp_seq_next;
2230 s->seq_ops.show = afinfo->seq_show;
2231 s->seq_ops.stop = tcp_seq_stop;
2232
2233 rc = seq_open(file, &s->seq_ops);
2234 if (rc)
2235 goto out_kfree;
2236 seq = file->private_data;
2237 seq->private = s;
2238 out:
2239 return rc;
2240 out_kfree:
2241 kfree(s);
2242 goto out;
2243 }
2244
2245 int tcp_proc_register(struct tcp_seq_afinfo *afinfo)
2246 {
2247 int rc = 0;
2248 struct proc_dir_entry *p;
2249
2250 if (!afinfo)
2251 return -EINVAL;
2252 afinfo->seq_fops->owner = afinfo->owner;
2253 afinfo->seq_fops->open = tcp_seq_open;
2254 afinfo->seq_fops->read = seq_read;
2255 afinfo->seq_fops->llseek = seq_lseek;
2256 afinfo->seq_fops->release = seq_release_private;
2257
2258 p = proc_net_fops_create(&init_net, afinfo->name, S_IRUGO, afinfo->seq_fops);
2259 if (p)
2260 p->data = afinfo;
2261 else
2262 rc = -ENOMEM;
2263 return rc;
2264 }
2265
2266 void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
2267 {
2268 if (!afinfo)
2269 return;
2270 proc_net_remove(&init_net, afinfo->name);
2271 memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
2272 }
2273
2274 static void get_openreq4(struct sock *sk, struct request_sock *req,
2275 char *tmpbuf, int i, int uid)
2276 {
2277 const struct inet_request_sock *ireq = inet_rsk(req);
2278 int ttd = req->expires - jiffies;
2279
2280 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
2281 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
2282 i,
2283 ireq->loc_addr,
2284 ntohs(inet_sk(sk)->sport),
2285 ireq->rmt_addr,
2286 ntohs(ireq->rmt_port),
2287 TCP_SYN_RECV,
2288 0, 0, /* could print option size, but that is af dependent. */
2289 1, /* timers active (only the expire timer) */
2290 jiffies_to_clock_t(ttd),
2291 req->retrans,
2292 uid,
2293 0, /* non standard timer */
2294 0, /* open_requests have no inode */
2295 atomic_read(&sk->sk_refcnt),
2296 req);
2297 }
2298
2299 static void get_tcp4_sock(struct sock *sk, char *tmpbuf, int i)
2300 {
2301 int timer_active;
2302 unsigned long timer_expires;
2303 struct tcp_sock *tp = tcp_sk(sk);
2304 const struct inet_connection_sock *icsk = inet_csk(sk);
2305 struct inet_sock *inet = inet_sk(sk);
2306 __be32 dest = inet->daddr;
2307 __be32 src = inet->rcv_saddr;
2308 __u16 destp = ntohs(inet->dport);
2309 __u16 srcp = ntohs(inet->sport);
2310
2311 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2312 timer_active = 1;
2313 timer_expires = icsk->icsk_timeout;
2314 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2315 timer_active = 4;
2316 timer_expires = icsk->icsk_timeout;
2317 } else if (timer_pending(&sk->sk_timer)) {
2318 timer_active = 2;
2319 timer_expires = sk->sk_timer.expires;
2320 } else {
2321 timer_active = 0;
2322 timer_expires = jiffies;
2323 }
2324
2325 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2326 "%08X %5d %8d %lu %d %p %u %u %u %u %d",
2327 i, src, srcp, dest, destp, sk->sk_state,
2328 tp->write_seq - tp->snd_una,
2329 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2330 (tp->rcv_nxt - tp->copied_seq),
2331 timer_active,
2332 jiffies_to_clock_t(timer_expires - jiffies),
2333 icsk->icsk_retransmits,
2334 sock_i_uid(sk),
2335 icsk->icsk_probes_out,
2336 sock_i_ino(sk),
2337 atomic_read(&sk->sk_refcnt), sk,
2338 icsk->icsk_rto,
2339 icsk->icsk_ack.ato,
2340 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2341 tp->snd_cwnd,
2342 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh);
2343 }
2344
2345 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2346 char *tmpbuf, int i)
2347 {
2348 __be32 dest, src;
2349 __u16 destp, srcp;
2350 int ttd = tw->tw_ttd - jiffies;
2351
2352 if (ttd < 0)
2353 ttd = 0;
2354
2355 dest = tw->tw_daddr;
2356 src = tw->tw_rcv_saddr;
2357 destp = ntohs(tw->tw_dport);
2358 srcp = ntohs(tw->tw_sport);
2359
2360 sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
2361 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p",
2362 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2363 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2364 atomic_read(&tw->tw_refcnt), tw);
2365 }
2366
2367 #define TMPSZ 150
2368
2369 static int tcp4_seq_show(struct seq_file *seq, void *v)
2370 {
2371 struct tcp_iter_state* st;
2372 char tmpbuf[TMPSZ + 1];
2373
2374 if (v == SEQ_START_TOKEN) {
2375 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2376 " sl local_address rem_address st tx_queue "
2377 "rx_queue tr tm->when retrnsmt uid timeout "
2378 "inode");
2379 goto out;
2380 }
2381 st = seq->private;
2382
2383 switch (st->state) {
2384 case TCP_SEQ_STATE_LISTENING:
2385 case TCP_SEQ_STATE_ESTABLISHED:
2386 get_tcp4_sock(v, tmpbuf, st->num);
2387 break;
2388 case TCP_SEQ_STATE_OPENREQ:
2389 get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid);
2390 break;
2391 case TCP_SEQ_STATE_TIME_WAIT:
2392 get_timewait4_sock(v, tmpbuf, st->num);
2393 break;
2394 }
2395 seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf);
2396 out:
2397 return 0;
2398 }
2399
2400 static struct file_operations tcp4_seq_fops;
2401 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2402 .owner = THIS_MODULE,
2403 .name = "tcp",
2404 .family = AF_INET,
2405 .seq_show = tcp4_seq_show,
2406 .seq_fops = &tcp4_seq_fops,
2407 };
2408
2409 int __init tcp4_proc_init(void)
2410 {
2411 return tcp_proc_register(&tcp4_seq_afinfo);
2412 }
2413
2414 void tcp4_proc_exit(void)
2415 {
2416 tcp_proc_unregister(&tcp4_seq_afinfo);
2417 }
2418 #endif /* CONFIG_PROC_FS */
2419
2420 DEFINE_PROTO_INUSE(tcp)
2421
2422 struct proto tcp_prot = {
2423 .name = "TCP",
2424 .owner = THIS_MODULE,
2425 .close = tcp_close,
2426 .connect = tcp_v4_connect,
2427 .disconnect = tcp_disconnect,
2428 .accept = inet_csk_accept,
2429 .ioctl = tcp_ioctl,
2430 .init = tcp_v4_init_sock,
2431 .destroy = tcp_v4_destroy_sock,
2432 .shutdown = tcp_shutdown,
2433 .setsockopt = tcp_setsockopt,
2434 .getsockopt = tcp_getsockopt,
2435 .recvmsg = tcp_recvmsg,
2436 .backlog_rcv = tcp_v4_do_rcv,
2437 .hash = tcp_v4_hash,
2438 .unhash = tcp_unhash,
2439 .get_port = tcp_v4_get_port,
2440 .enter_memory_pressure = tcp_enter_memory_pressure,
2441 .sockets_allocated = &tcp_sockets_allocated,
2442 .orphan_count = &tcp_orphan_count,
2443 .memory_allocated = &tcp_memory_allocated,
2444 .memory_pressure = &tcp_memory_pressure,
2445 .sysctl_mem = sysctl_tcp_mem,
2446 .sysctl_wmem = sysctl_tcp_wmem,
2447 .sysctl_rmem = sysctl_tcp_rmem,
2448 .max_header = MAX_TCP_HEADER,
2449 .obj_size = sizeof(struct tcp_sock),
2450 .twsk_prot = &tcp_timewait_sock_ops,
2451 .rsk_prot = &tcp_request_sock_ops,
2452 #ifdef CONFIG_COMPAT
2453 .compat_setsockopt = compat_tcp_setsockopt,
2454 .compat_getsockopt = compat_tcp_getsockopt,
2455 #endif
2456 REF_PROTO_INUSE(tcp)
2457 };
2458
2459 void __init tcp_v4_init(struct net_proto_family *ops)
2460 {
2461 if (inet_csk_ctl_sock_create(&tcp_socket, PF_INET, SOCK_RAW,
2462 IPPROTO_TCP) < 0)
2463 panic("Failed to create the TCP control socket.\n");
2464 }
2465
2466 EXPORT_SYMBOL(ipv4_specific);
2467 EXPORT_SYMBOL(tcp_hashinfo);
2468 EXPORT_SYMBOL(tcp_prot);
2469 EXPORT_SYMBOL(tcp_unhash);
2470 EXPORT_SYMBOL(tcp_v4_conn_request);
2471 EXPORT_SYMBOL(tcp_v4_connect);
2472 EXPORT_SYMBOL(tcp_v4_do_rcv);
2473 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2474 EXPORT_SYMBOL(tcp_v4_send_check);
2475 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2476
2477 #ifdef CONFIG_PROC_FS
2478 EXPORT_SYMBOL(tcp_proc_register);
2479 EXPORT_SYMBOL(tcp_proc_unregister);
2480 #endif
2481 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2482
WRT350N Kernel Patches