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tcp: Fix MD5 signatures for non-linear skbs
[deliverable/linux.git] / net / ipv4 / tcp_ipv4.c
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Implementation of the Transmission Control Protocol(TCP).
7 *
8 * IPv4 specific functions
9 *
10 *
11 * code split from:
12 * linux/ipv4/tcp.c
13 * linux/ipv4/tcp_input.c
14 * linux/ipv4/tcp_output.c
15 *
16 * See tcp.c for author information
17 *
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
22 */
23
24 /*
25 * Changes:
26 * David S. Miller : New socket lookup architecture.
27 * This code is dedicated to John Dyson.
28 * David S. Miller : Change semantics of established hash,
29 * half is devoted to TIME_WAIT sockets
30 * and the rest go in the other half.
31 * Andi Kleen : Add support for syncookies and fixed
32 * some bugs: ip options weren't passed to
33 * the TCP layer, missed a check for an
34 * ACK bit.
35 * Andi Kleen : Implemented fast path mtu discovery.
36 * Fixed many serious bugs in the
37 * request_sock handling and moved
38 * most of it into the af independent code.
39 * Added tail drop and some other bugfixes.
40 * Added new listen semantics.
41 * Mike McLagan : Routing by source
42 * Juan Jose Ciarlante: ip_dynaddr bits
43 * Andi Kleen: various fixes.
44 * Vitaly E. Lavrov : Transparent proxy revived after year
45 * coma.
46 * Andi Kleen : Fix new listen.
47 * Andi Kleen : Fix accept error reporting.
48 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which
49 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind
50 * a single port at the same time.
51 */
52
53
54 #include <linux/types.h>
55 #include <linux/fcntl.h>
56 #include <linux/module.h>
57 #include <linux/random.h>
58 #include <linux/cache.h>
59 #include <linux/jhash.h>
60 #include <linux/init.h>
61 #include <linux/times.h>
62
63 #include <net/net_namespace.h>
64 #include <net/icmp.h>
65 #include <net/inet_hashtables.h>
66 #include <net/tcp.h>
67 #include <net/transp_v6.h>
68 #include <net/ipv6.h>
69 #include <net/inet_common.h>
70 #include <net/timewait_sock.h>
71 #include <net/xfrm.h>
72 #include <net/netdma.h>
73
74 #include <linux/inet.h>
75 #include <linux/ipv6.h>
76 #include <linux/stddef.h>
77 #include <linux/proc_fs.h>
78 #include <linux/seq_file.h>
79
80 #include <linux/crypto.h>
81 #include <linux/scatterlist.h>
82
83 int sysctl_tcp_tw_reuse __read_mostly;
84 int sysctl_tcp_low_latency __read_mostly;
85
86
87 #ifdef CONFIG_TCP_MD5SIG
88 static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
89 __be32 addr);
90 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
91 __be32 daddr, __be32 saddr, struct tcphdr *th);
92 #else
93 static inline
94 struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
95 {
96 return NULL;
97 }
98 #endif
99
100 struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
101 .lhash_lock = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
102 .lhash_users = ATOMIC_INIT(0),
103 .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
104 };
105
106 static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
107 {
108 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
109 ip_hdr(skb)->saddr,
110 tcp_hdr(skb)->dest,
111 tcp_hdr(skb)->source);
112 }
113
114 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
115 {
116 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
117 struct tcp_sock *tp = tcp_sk(sk);
118
119 /* With PAWS, it is safe from the viewpoint
120 of data integrity. Even without PAWS it is safe provided sequence
121 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
122
123 Actually, the idea is close to VJ's one, only timestamp cache is
124 held not per host, but per port pair and TW bucket is used as state
125 holder.
126
127 If TW bucket has been already destroyed we fall back to VJ's scheme
128 and use initial timestamp retrieved from peer table.
129 */
130 if (tcptw->tw_ts_recent_stamp &&
131 (twp == NULL || (sysctl_tcp_tw_reuse &&
132 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
133 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
134 if (tp->write_seq == 0)
135 tp->write_seq = 1;
136 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
137 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
138 sock_hold(sktw);
139 return 1;
140 }
141
142 return 0;
143 }
144
145 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
146
147 /* This will initiate an outgoing connection. */
148 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
149 {
150 struct inet_sock *inet = inet_sk(sk);
151 struct tcp_sock *tp = tcp_sk(sk);
152 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
153 struct rtable *rt;
154 __be32 daddr, nexthop;
155 int tmp;
156 int err;
157
158 if (addr_len < sizeof(struct sockaddr_in))
159 return -EINVAL;
160
161 if (usin->sin_family != AF_INET)
162 return -EAFNOSUPPORT;
163
164 nexthop = daddr = usin->sin_addr.s_addr;
165 if (inet->opt && inet->opt->srr) {
166 if (!daddr)
167 return -EINVAL;
168 nexthop = inet->opt->faddr;
169 }
170
171 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
172 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
173 IPPROTO_TCP,
174 inet->sport, usin->sin_port, sk, 1);
175 if (tmp < 0) {
176 if (tmp == -ENETUNREACH)
177 IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
178 return tmp;
179 }
180
181 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
182 ip_rt_put(rt);
183 return -ENETUNREACH;
184 }
185
186 if (!inet->opt || !inet->opt->srr)
187 daddr = rt->rt_dst;
188
189 if (!inet->saddr)
190 inet->saddr = rt->rt_src;
191 inet->rcv_saddr = inet->saddr;
192
193 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
194 /* Reset inherited state */
195 tp->rx_opt.ts_recent = 0;
196 tp->rx_opt.ts_recent_stamp = 0;
197 tp->write_seq = 0;
198 }
199
200 if (tcp_death_row.sysctl_tw_recycle &&
201 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
202 struct inet_peer *peer = rt_get_peer(rt);
203 /*
204 * VJ's idea. We save last timestamp seen from
205 * the destination in peer table, when entering state
206 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
207 * when trying new connection.
208 */
209 if (peer != NULL &&
210 peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {
211 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
212 tp->rx_opt.ts_recent = peer->tcp_ts;
213 }
214 }
215
216 inet->dport = usin->sin_port;
217 inet->daddr = daddr;
218
219 inet_csk(sk)->icsk_ext_hdr_len = 0;
220 if (inet->opt)
221 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
222
223 tp->rx_opt.mss_clamp = 536;
224
225 /* Socket identity is still unknown (sport may be zero).
226 * However we set state to SYN-SENT and not releasing socket
227 * lock select source port, enter ourselves into the hash tables and
228 * complete initialization after this.
229 */
230 tcp_set_state(sk, TCP_SYN_SENT);
231 err = inet_hash_connect(&tcp_death_row, sk);
232 if (err)
233 goto failure;
234
235 err = ip_route_newports(&rt, IPPROTO_TCP,
236 inet->sport, inet->dport, sk);
237 if (err)
238 goto failure;
239
240 /* OK, now commit destination to socket. */
241 sk->sk_gso_type = SKB_GSO_TCPV4;
242 sk_setup_caps(sk, &rt->u.dst);
243
244 if (!tp->write_seq)
245 tp->write_seq = secure_tcp_sequence_number(inet->saddr,
246 inet->daddr,
247 inet->sport,
248 usin->sin_port);
249
250 inet->id = tp->write_seq ^ jiffies;
251
252 err = tcp_connect(sk);
253 rt = NULL;
254 if (err)
255 goto failure;
256
257 return 0;
258
259 failure:
260 /*
261 * This unhashes the socket and releases the local port,
262 * if necessary.
263 */
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 const int type = icmp_hdr(skb)->type;
341 const int code = icmp_hdr(skb)->code;
342 struct sock *sk;
343 __u32 seq;
344 int err;
345 struct net *net = dev_net(skb->dev);
346
347 if (skb->len < (iph->ihl << 2) + 8) {
348 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
349 return;
350 }
351
352 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
353 iph->saddr, th->source, inet_iif(skb));
354 if (!sk) {
355 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
356 return;
357 }
358 if (sk->sk_state == TCP_TIME_WAIT) {
359 inet_twsk_put(inet_twsk(sk));
360 return;
361 }
362
363 bh_lock_sock(sk);
364 /* If too many ICMPs get dropped on busy
365 * servers this needs to be solved differently.
366 */
367 if (sock_owned_by_user(sk))
368 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
369
370 if (sk->sk_state == TCP_CLOSE)
371 goto out;
372
373 tp = tcp_sk(sk);
374 seq = ntohl(th->seq);
375 if (sk->sk_state != TCP_LISTEN &&
376 !between(seq, tp->snd_una, tp->snd_nxt)) {
377 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
378 goto out;
379 }
380
381 switch (type) {
382 case ICMP_SOURCE_QUENCH:
383 /* Just silently ignore these. */
384 goto out;
385 case ICMP_PARAMETERPROB:
386 err = EPROTO;
387 break;
388 case ICMP_DEST_UNREACH:
389 if (code > NR_ICMP_UNREACH)
390 goto out;
391
392 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
393 if (!sock_owned_by_user(sk))
394 do_pmtu_discovery(sk, iph, info);
395 goto out;
396 }
397
398 err = icmp_err_convert[code].errno;
399 break;
400 case ICMP_TIME_EXCEEDED:
401 err = EHOSTUNREACH;
402 break;
403 default:
404 goto out;
405 }
406
407 switch (sk->sk_state) {
408 struct request_sock *req, **prev;
409 case TCP_LISTEN:
410 if (sock_owned_by_user(sk))
411 goto out;
412
413 req = inet_csk_search_req(sk, &prev, th->dest,
414 iph->daddr, iph->saddr);
415 if (!req)
416 goto out;
417
418 /* ICMPs are not backlogged, hence we cannot get
419 an established socket here.
420 */
421 BUG_TRAP(!req->sk);
422
423 if (seq != tcp_rsk(req)->snt_isn) {
424 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
425 goto out;
426 }
427
428 /*
429 * Still in SYN_RECV, just remove it silently.
430 * There is no good way to pass the error to the newly
431 * created socket, and POSIX does not want network
432 * errors returned from accept().
433 */
434 inet_csk_reqsk_queue_drop(sk, req, prev);
435 goto out;
436
437 case TCP_SYN_SENT:
438 case TCP_SYN_RECV: /* Cannot happen.
439 It can f.e. if SYNs crossed.
440 */
441 if (!sock_owned_by_user(sk)) {
442 sk->sk_err = err;
443
444 sk->sk_error_report(sk);
445
446 tcp_done(sk);
447 } else {
448 sk->sk_err_soft = err;
449 }
450 goto out;
451 }
452
453 /* If we've already connected we will keep trying
454 * until we time out, or the user gives up.
455 *
456 * rfc1122 4.2.3.9 allows to consider as hard errors
457 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
458 * but it is obsoleted by pmtu discovery).
459 *
460 * Note, that in modern internet, where routing is unreliable
461 * and in each dark corner broken firewalls sit, sending random
462 * errors ordered by their masters even this two messages finally lose
463 * their original sense (even Linux sends invalid PORT_UNREACHs)
464 *
465 * Now we are in compliance with RFCs.
466 * --ANK (980905)
467 */
468
469 inet = inet_sk(sk);
470 if (!sock_owned_by_user(sk) && inet->recverr) {
471 sk->sk_err = err;
472 sk->sk_error_report(sk);
473 } else { /* Only an error on timeout */
474 sk->sk_err_soft = err;
475 }
476
477 out:
478 bh_unlock_sock(sk);
479 sock_put(sk);
480 }
481
482 /* This routine computes an IPv4 TCP checksum. */
483 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
484 {
485 struct inet_sock *inet = inet_sk(sk);
486 struct tcphdr *th = tcp_hdr(skb);
487
488 if (skb->ip_summed == CHECKSUM_PARTIAL) {
489 th->check = ~tcp_v4_check(len, inet->saddr,
490 inet->daddr, 0);
491 skb->csum_start = skb_transport_header(skb) - skb->head;
492 skb->csum_offset = offsetof(struct tcphdr, check);
493 } else {
494 th->check = tcp_v4_check(len, inet->saddr, inet->daddr,
495 csum_partial((char *)th,
496 th->doff << 2,
497 skb->csum));
498 }
499 }
500
501 int tcp_v4_gso_send_check(struct sk_buff *skb)
502 {
503 const struct iphdr *iph;
504 struct tcphdr *th;
505
506 if (!pskb_may_pull(skb, sizeof(*th)))
507 return -EINVAL;
508
509 iph = ip_hdr(skb);
510 th = tcp_hdr(skb);
511
512 th->check = 0;
513 th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0);
514 skb->csum_start = skb_transport_header(skb) - skb->head;
515 skb->csum_offset = offsetof(struct tcphdr, check);
516 skb->ip_summed = CHECKSUM_PARTIAL;
517 return 0;
518 }
519
520 /*
521 * This routine will send an RST to the other tcp.
522 *
523 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
524 * for reset.
525 * Answer: if a packet caused RST, it is not for a socket
526 * existing in our system, if it is matched to a socket,
527 * it is just duplicate segment or bug in other side's TCP.
528 * So that we build reply only basing on parameters
529 * arrived with segment.
530 * Exception: precedence violation. We do not implement it in any case.
531 */
532
533 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
534 {
535 struct tcphdr *th = tcp_hdr(skb);
536 struct {
537 struct tcphdr th;
538 #ifdef CONFIG_TCP_MD5SIG
539 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
540 #endif
541 } rep;
542 struct ip_reply_arg arg;
543 #ifdef CONFIG_TCP_MD5SIG
544 struct tcp_md5sig_key *key;
545 #endif
546 struct net *net;
547
548 /* Never send a reset in response to a reset. */
549 if (th->rst)
550 return;
551
552 if (skb->rtable->rt_type != RTN_LOCAL)
553 return;
554
555 /* Swap the send and the receive. */
556 memset(&rep, 0, sizeof(rep));
557 rep.th.dest = th->source;
558 rep.th.source = th->dest;
559 rep.th.doff = sizeof(struct tcphdr) / 4;
560 rep.th.rst = 1;
561
562 if (th->ack) {
563 rep.th.seq = th->ack_seq;
564 } else {
565 rep.th.ack = 1;
566 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
567 skb->len - (th->doff << 2));
568 }
569
570 memset(&arg, 0, sizeof(arg));
571 arg.iov[0].iov_base = (unsigned char *)&rep;
572 arg.iov[0].iov_len = sizeof(rep.th);
573
574 #ifdef CONFIG_TCP_MD5SIG
575 key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
576 if (key) {
577 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
578 (TCPOPT_NOP << 16) |
579 (TCPOPT_MD5SIG << 8) |
580 TCPOLEN_MD5SIG);
581 /* Update length and the length the header thinks exists */
582 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
583 rep.th.doff = arg.iov[0].iov_len / 4;
584
585 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
586 key, ip_hdr(skb)->daddr,
587 ip_hdr(skb)->saddr, &rep.th);
588 }
589 #endif
590 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
591 ip_hdr(skb)->saddr, /* XXX */
592 sizeof(struct tcphdr), IPPROTO_TCP, 0);
593 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
594
595 net = dev_net(skb->dst->dev);
596 ip_send_reply(net->ipv4.tcp_sock, skb,
597 &arg, arg.iov[0].iov_len);
598
599 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
600 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
601 }
602
603 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
604 outside socket context is ugly, certainly. What can I do?
605 */
606
607 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
608 u32 win, u32 ts, int oif,
609 struct tcp_md5sig_key *key)
610 {
611 struct tcphdr *th = tcp_hdr(skb);
612 struct {
613 struct tcphdr th;
614 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
615 #ifdef CONFIG_TCP_MD5SIG
616 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
617 #endif
618 ];
619 } rep;
620 struct ip_reply_arg arg;
621 struct net *net = dev_net(skb->dev);
622
623 memset(&rep.th, 0, sizeof(struct tcphdr));
624 memset(&arg, 0, sizeof(arg));
625
626 arg.iov[0].iov_base = (unsigned char *)&rep;
627 arg.iov[0].iov_len = sizeof(rep.th);
628 if (ts) {
629 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
630 (TCPOPT_TIMESTAMP << 8) |
631 TCPOLEN_TIMESTAMP);
632 rep.opt[1] = htonl(tcp_time_stamp);
633 rep.opt[2] = htonl(ts);
634 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
635 }
636
637 /* Swap the send and the receive. */
638 rep.th.dest = th->source;
639 rep.th.source = th->dest;
640 rep.th.doff = arg.iov[0].iov_len / 4;
641 rep.th.seq = htonl(seq);
642 rep.th.ack_seq = htonl(ack);
643 rep.th.ack = 1;
644 rep.th.window = htons(win);
645
646 #ifdef CONFIG_TCP_MD5SIG
647 if (key) {
648 int offset = (ts) ? 3 : 0;
649
650 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
651 (TCPOPT_NOP << 16) |
652 (TCPOPT_MD5SIG << 8) |
653 TCPOLEN_MD5SIG);
654 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
655 rep.th.doff = arg.iov[0].iov_len/4;
656
657 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
658 key, ip_hdr(skb)->daddr,
659 ip_hdr(skb)->saddr, &rep.th);
660 }
661 #endif
662 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
663 ip_hdr(skb)->saddr, /* XXX */
664 arg.iov[0].iov_len, IPPROTO_TCP, 0);
665 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
666 if (oif)
667 arg.bound_dev_if = oif;
668
669 ip_send_reply(net->ipv4.tcp_sock, skb,
670 &arg, arg.iov[0].iov_len);
671
672 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
673 }
674
675 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
676 {
677 struct inet_timewait_sock *tw = inet_twsk(sk);
678 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
679
680 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
681 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
682 tcptw->tw_ts_recent,
683 tw->tw_bound_dev_if,
684 tcp_twsk_md5_key(tcptw)
685 );
686
687 inet_twsk_put(tw);
688 }
689
690 static void tcp_v4_reqsk_send_ack(struct sk_buff *skb,
691 struct request_sock *req)
692 {
693 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
694 tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
695 req->ts_recent,
696 0,
697 tcp_v4_md5_do_lookup(skb->sk, ip_hdr(skb)->daddr));
698 }
699
700 /*
701 * Send a SYN-ACK after having received a SYN.
702 * This still operates on a request_sock only, not on a big
703 * socket.
704 */
705 static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
706 struct dst_entry *dst)
707 {
708 const struct inet_request_sock *ireq = inet_rsk(req);
709 int err = -1;
710 struct sk_buff * skb;
711
712 /* First, grab a route. */
713 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
714 return -1;
715
716 skb = tcp_make_synack(sk, dst, req);
717
718 if (skb) {
719 struct tcphdr *th = tcp_hdr(skb);
720
721 th->check = tcp_v4_check(skb->len,
722 ireq->loc_addr,
723 ireq->rmt_addr,
724 csum_partial((char *)th, skb->len,
725 skb->csum));
726
727 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
728 ireq->rmt_addr,
729 ireq->opt);
730 err = net_xmit_eval(err);
731 }
732
733 dst_release(dst);
734 return err;
735 }
736
737 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req)
738 {
739 return __tcp_v4_send_synack(sk, req, NULL);
740 }
741
742 /*
743 * IPv4 request_sock destructor.
744 */
745 static void tcp_v4_reqsk_destructor(struct request_sock *req)
746 {
747 kfree(inet_rsk(req)->opt);
748 }
749
750 #ifdef CONFIG_SYN_COOKIES
751 static void syn_flood_warning(struct sk_buff *skb)
752 {
753 static unsigned long warntime;
754
755 if (time_after(jiffies, (warntime + HZ * 60))) {
756 warntime = jiffies;
757 printk(KERN_INFO
758 "possible SYN flooding on port %d. Sending cookies.\n",
759 ntohs(tcp_hdr(skb)->dest));
760 }
761 }
762 #endif
763
764 /*
765 * Save and compile IPv4 options into the request_sock if needed.
766 */
767 static struct ip_options *tcp_v4_save_options(struct sock *sk,
768 struct sk_buff *skb)
769 {
770 struct ip_options *opt = &(IPCB(skb)->opt);
771 struct ip_options *dopt = NULL;
772
773 if (opt && opt->optlen) {
774 int opt_size = optlength(opt);
775 dopt = kmalloc(opt_size, GFP_ATOMIC);
776 if (dopt) {
777 if (ip_options_echo(dopt, skb)) {
778 kfree(dopt);
779 dopt = NULL;
780 }
781 }
782 }
783 return dopt;
784 }
785
786 #ifdef CONFIG_TCP_MD5SIG
787 /*
788 * RFC2385 MD5 checksumming requires a mapping of
789 * IP address->MD5 Key.
790 * We need to maintain these in the sk structure.
791 */
792
793 /* Find the Key structure for an address. */
794 static struct tcp_md5sig_key *
795 tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
796 {
797 struct tcp_sock *tp = tcp_sk(sk);
798 int i;
799
800 if (!tp->md5sig_info || !tp->md5sig_info->entries4)
801 return NULL;
802 for (i = 0; i < tp->md5sig_info->entries4; i++) {
803 if (tp->md5sig_info->keys4[i].addr == addr)
804 return &tp->md5sig_info->keys4[i].base;
805 }
806 return NULL;
807 }
808
809 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
810 struct sock *addr_sk)
811 {
812 return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->daddr);
813 }
814
815 EXPORT_SYMBOL(tcp_v4_md5_lookup);
816
817 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
818 struct request_sock *req)
819 {
820 return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
821 }
822
823 /* This can be called on a newly created socket, from other files */
824 int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
825 u8 *newkey, u8 newkeylen)
826 {
827 /* Add Key to the list */
828 struct tcp_md5sig_key *key;
829 struct tcp_sock *tp = tcp_sk(sk);
830 struct tcp4_md5sig_key *keys;
831
832 key = tcp_v4_md5_do_lookup(sk, addr);
833 if (key) {
834 /* Pre-existing entry - just update that one. */
835 kfree(key->key);
836 key->key = newkey;
837 key->keylen = newkeylen;
838 } else {
839 struct tcp_md5sig_info *md5sig;
840
841 if (!tp->md5sig_info) {
842 tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
843 GFP_ATOMIC);
844 if (!tp->md5sig_info) {
845 kfree(newkey);
846 return -ENOMEM;
847 }
848 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
849 }
850 if (tcp_alloc_md5sig_pool() == NULL) {
851 kfree(newkey);
852 return -ENOMEM;
853 }
854 md5sig = tp->md5sig_info;
855
856 if (md5sig->alloced4 == md5sig->entries4) {
857 keys = kmalloc((sizeof(*keys) *
858 (md5sig->entries4 + 1)), GFP_ATOMIC);
859 if (!keys) {
860 kfree(newkey);
861 tcp_free_md5sig_pool();
862 return -ENOMEM;
863 }
864
865 if (md5sig->entries4)
866 memcpy(keys, md5sig->keys4,
867 sizeof(*keys) * md5sig->entries4);
868
869 /* Free old key list, and reference new one */
870 kfree(md5sig->keys4);
871 md5sig->keys4 = keys;
872 md5sig->alloced4++;
873 }
874 md5sig->entries4++;
875 md5sig->keys4[md5sig->entries4 - 1].addr = addr;
876 md5sig->keys4[md5sig->entries4 - 1].base.key = newkey;
877 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
878 }
879 return 0;
880 }
881
882 EXPORT_SYMBOL(tcp_v4_md5_do_add);
883
884 static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
885 u8 *newkey, u8 newkeylen)
886 {
887 return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->daddr,
888 newkey, newkeylen);
889 }
890
891 int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
892 {
893 struct tcp_sock *tp = tcp_sk(sk);
894 int i;
895
896 for (i = 0; i < tp->md5sig_info->entries4; i++) {
897 if (tp->md5sig_info->keys4[i].addr == addr) {
898 /* Free the key */
899 kfree(tp->md5sig_info->keys4[i].base.key);
900 tp->md5sig_info->entries4--;
901
902 if (tp->md5sig_info->entries4 == 0) {
903 kfree(tp->md5sig_info->keys4);
904 tp->md5sig_info->keys4 = NULL;
905 tp->md5sig_info->alloced4 = 0;
906 } else if (tp->md5sig_info->entries4 != i) {
907 /* Need to do some manipulation */
908 memmove(&tp->md5sig_info->keys4[i],
909 &tp->md5sig_info->keys4[i+1],
910 (tp->md5sig_info->entries4 - i) *
911 sizeof(struct tcp4_md5sig_key));
912 }
913 tcp_free_md5sig_pool();
914 return 0;
915 }
916 }
917 return -ENOENT;
918 }
919
920 EXPORT_SYMBOL(tcp_v4_md5_do_del);
921
922 static void tcp_v4_clear_md5_list(struct sock *sk)
923 {
924 struct tcp_sock *tp = tcp_sk(sk);
925
926 /* Free each key, then the set of key keys,
927 * the crypto element, and then decrement our
928 * hold on the last resort crypto.
929 */
930 if (tp->md5sig_info->entries4) {
931 int i;
932 for (i = 0; i < tp->md5sig_info->entries4; i++)
933 kfree(tp->md5sig_info->keys4[i].base.key);
934 tp->md5sig_info->entries4 = 0;
935 tcp_free_md5sig_pool();
936 }
937 if (tp->md5sig_info->keys4) {
938 kfree(tp->md5sig_info->keys4);
939 tp->md5sig_info->keys4 = NULL;
940 tp->md5sig_info->alloced4 = 0;
941 }
942 }
943
944 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
945 int optlen)
946 {
947 struct tcp_md5sig cmd;
948 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
949 u8 *newkey;
950
951 if (optlen < sizeof(cmd))
952 return -EINVAL;
953
954 if (copy_from_user(&cmd, optval, sizeof(cmd)))
955 return -EFAULT;
956
957 if (sin->sin_family != AF_INET)
958 return -EINVAL;
959
960 if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
961 if (!tcp_sk(sk)->md5sig_info)
962 return -ENOENT;
963 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
964 }
965
966 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
967 return -EINVAL;
968
969 if (!tcp_sk(sk)->md5sig_info) {
970 struct tcp_sock *tp = tcp_sk(sk);
971 struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL);
972
973 if (!p)
974 return -EINVAL;
975
976 tp->md5sig_info = p;
977 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
978 }
979
980 newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
981 if (!newkey)
982 return -ENOMEM;
983 return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
984 newkey, cmd.tcpm_keylen);
985 }
986
987 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
988 __be32 daddr, __be32 saddr, int nbytes)
989 {
990 struct tcp4_pseudohdr *bp;
991 struct scatterlist sg;
992
993 bp = &hp->md5_blk.ip4;
994
995 /*
996 * 1. the TCP pseudo-header (in the order: source IP address,
997 * destination IP address, zero-padded protocol number, and
998 * segment length)
999 */
1000 bp->saddr = saddr;
1001 bp->daddr = daddr;
1002 bp->pad = 0;
1003 bp->protocol = IPPROTO_TCP;
1004 bp->len = cpu_to_be16(nbytes);
1005
1006 sg_init_one(&sg, bp, sizeof(*bp));
1007 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1008 }
1009
1010 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
1011 __be32 daddr, __be32 saddr, struct tcphdr *th)
1012 {
1013 struct tcp_md5sig_pool *hp;
1014 struct hash_desc *desc;
1015
1016 hp = tcp_get_md5sig_pool();
1017 if (!hp)
1018 goto clear_hash_noput;
1019 desc = &hp->md5_desc;
1020
1021 if (crypto_hash_init(desc))
1022 goto clear_hash;
1023 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1024 goto clear_hash;
1025 if (tcp_md5_hash_header(hp, th))
1026 goto clear_hash;
1027 if (tcp_md5_hash_key(hp, key))
1028 goto clear_hash;
1029 if (crypto_hash_final(desc, md5_hash))
1030 goto clear_hash;
1031
1032 tcp_put_md5sig_pool();
1033 return 0;
1034
1035 clear_hash:
1036 tcp_put_md5sig_pool();
1037 clear_hash_noput:
1038 memset(md5_hash, 0, 16);
1039 return 1;
1040 }
1041
1042 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1043 struct sock *sk, struct request_sock *req,
1044 struct sk_buff *skb)
1045 {
1046 struct tcp_md5sig_pool *hp;
1047 struct hash_desc *desc;
1048 struct tcphdr *th = tcp_hdr(skb);
1049 __be32 saddr, daddr;
1050
1051 if (sk) {
1052 saddr = inet_sk(sk)->saddr;
1053 daddr = inet_sk(sk)->daddr;
1054 } else if (req) {
1055 saddr = inet_rsk(req)->loc_addr;
1056 daddr = inet_rsk(req)->rmt_addr;
1057 } else {
1058 const struct iphdr *iph = ip_hdr(skb);
1059 saddr = iph->saddr;
1060 daddr = iph->daddr;
1061 }
1062
1063 hp = tcp_get_md5sig_pool();
1064 if (!hp)
1065 goto clear_hash_noput;
1066 desc = &hp->md5_desc;
1067
1068 if (crypto_hash_init(desc))
1069 goto clear_hash;
1070
1071 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1072 goto clear_hash;
1073 if (tcp_md5_hash_header(hp, th))
1074 goto clear_hash;
1075 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1076 goto clear_hash;
1077 if (tcp_md5_hash_key(hp, key))
1078 goto clear_hash;
1079 if (crypto_hash_final(desc, md5_hash))
1080 goto clear_hash;
1081
1082 tcp_put_md5sig_pool();
1083 return 0;
1084
1085 clear_hash:
1086 tcp_put_md5sig_pool();
1087 clear_hash_noput:
1088 memset(md5_hash, 0, 16);
1089 return 1;
1090 }
1091
1092 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1093
1094 static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1095 {
1096 /*
1097 * This gets called for each TCP segment that arrives
1098 * so we want to be efficient.
1099 * We have 3 drop cases:
1100 * o No MD5 hash and one expected.
1101 * o MD5 hash and we're not expecting one.
1102 * o MD5 hash and its wrong.
1103 */
1104 __u8 *hash_location = NULL;
1105 struct tcp_md5sig_key *hash_expected;
1106 const struct iphdr *iph = ip_hdr(skb);
1107 struct tcphdr *th = tcp_hdr(skb);
1108 int genhash;
1109 unsigned char newhash[16];
1110
1111 hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1112 hash_location = tcp_parse_md5sig_option(th);
1113
1114 /* We've parsed the options - do we have a hash? */
1115 if (!hash_expected && !hash_location)
1116 return 0;
1117
1118 if (hash_expected && !hash_location) {
1119 LIMIT_NETDEBUG(KERN_INFO "MD5 Hash expected but NOT found "
1120 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1121 NIPQUAD(iph->saddr), ntohs(th->source),
1122 NIPQUAD(iph->daddr), ntohs(th->dest));
1123 return 1;
1124 }
1125
1126 if (!hash_expected && hash_location) {
1127 LIMIT_NETDEBUG(KERN_INFO "MD5 Hash NOT expected but found "
1128 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)\n",
1129 NIPQUAD(iph->saddr), ntohs(th->source),
1130 NIPQUAD(iph->daddr), ntohs(th->dest));
1131 return 1;
1132 }
1133
1134 /* Okay, so this is hash_expected and hash_location -
1135 * so we need to calculate the checksum.
1136 */
1137 genhash = tcp_v4_md5_hash_skb(newhash,
1138 hash_expected,
1139 NULL, NULL, skb);
1140
1141 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1142 if (net_ratelimit()) {
1143 printk(KERN_INFO "MD5 Hash failed for "
1144 "(" NIPQUAD_FMT ", %d)->(" NIPQUAD_FMT ", %d)%s\n",
1145 NIPQUAD(iph->saddr), ntohs(th->source),
1146 NIPQUAD(iph->daddr), ntohs(th->dest),
1147 genhash ? " tcp_v4_calc_md5_hash failed" : "");
1148 }
1149 return 1;
1150 }
1151 return 0;
1152 }
1153
1154 #endif
1155
1156 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1157 .family = PF_INET,
1158 .obj_size = sizeof(struct tcp_request_sock),
1159 .rtx_syn_ack = tcp_v4_send_synack,
1160 .send_ack = tcp_v4_reqsk_send_ack,
1161 .destructor = tcp_v4_reqsk_destructor,
1162 .send_reset = tcp_v4_send_reset,
1163 };
1164
1165 #ifdef CONFIG_TCP_MD5SIG
1166 static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1167 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1168 };
1169 #endif
1170
1171 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1172 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1173 .twsk_unique = tcp_twsk_unique,
1174 .twsk_destructor= tcp_twsk_destructor,
1175 };
1176
1177 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1178 {
1179 struct inet_request_sock *ireq;
1180 struct tcp_options_received tmp_opt;
1181 struct request_sock *req;
1182 __be32 saddr = ip_hdr(skb)->saddr;
1183 __be32 daddr = ip_hdr(skb)->daddr;
1184 __u32 isn = TCP_SKB_CB(skb)->when;
1185 struct dst_entry *dst = NULL;
1186 #ifdef CONFIG_SYN_COOKIES
1187 int want_cookie = 0;
1188 #else
1189 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
1190 #endif
1191
1192 /* Never answer to SYNs send to broadcast or multicast */
1193 if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1194 goto drop;
1195
1196 /* TW buckets are converted to open requests without
1197 * limitations, they conserve resources and peer is
1198 * evidently real one.
1199 */
1200 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1201 #ifdef CONFIG_SYN_COOKIES
1202 if (sysctl_tcp_syncookies) {
1203 want_cookie = 1;
1204 } else
1205 #endif
1206 goto drop;
1207 }
1208
1209 /* Accept backlog is full. If we have already queued enough
1210 * of warm entries in syn queue, drop request. It is better than
1211 * clogging syn queue with openreqs with exponentially increasing
1212 * timeout.
1213 */
1214 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1215 goto drop;
1216
1217 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1218 if (!req)
1219 goto drop;
1220
1221 #ifdef CONFIG_TCP_MD5SIG
1222 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1223 #endif
1224
1225 tcp_clear_options(&tmp_opt);
1226 tmp_opt.mss_clamp = 536;
1227 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
1228
1229 tcp_parse_options(skb, &tmp_opt, 0);
1230
1231 if (want_cookie && !tmp_opt.saw_tstamp)
1232 tcp_clear_options(&tmp_opt);
1233
1234 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
1235 /* Some OSes (unknown ones, but I see them on web server, which
1236 * contains information interesting only for windows'
1237 * users) do not send their stamp in SYN. It is easy case.
1238 * We simply do not advertise TS support.
1239 */
1240 tmp_opt.saw_tstamp = 0;
1241 tmp_opt.tstamp_ok = 0;
1242 }
1243 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1244
1245 tcp_openreq_init(req, &tmp_opt, skb);
1246
1247 if (security_inet_conn_request(sk, skb, req))
1248 goto drop_and_free;
1249
1250 ireq = inet_rsk(req);
1251 ireq->loc_addr = daddr;
1252 ireq->rmt_addr = saddr;
1253 ireq->opt = tcp_v4_save_options(sk, skb);
1254 if (!want_cookie)
1255 TCP_ECN_create_request(req, tcp_hdr(skb));
1256
1257 if (want_cookie) {
1258 #ifdef CONFIG_SYN_COOKIES
1259 syn_flood_warning(skb);
1260 req->cookie_ts = tmp_opt.tstamp_ok;
1261 #endif
1262 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1263 } else if (!isn) {
1264 struct inet_peer *peer = NULL;
1265
1266 /* VJ's idea. We save last timestamp seen
1267 * from the destination in peer table, when entering
1268 * state TIME-WAIT, and check against it before
1269 * accepting new connection request.
1270 *
1271 * If "isn" is not zero, this request hit alive
1272 * timewait bucket, so that all the necessary checks
1273 * are made in the function processing timewait state.
1274 */
1275 if (tmp_opt.saw_tstamp &&
1276 tcp_death_row.sysctl_tw_recycle &&
1277 (dst = inet_csk_route_req(sk, req)) != NULL &&
1278 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1279 peer->v4daddr == saddr) {
1280 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1281 (s32)(peer->tcp_ts - req->ts_recent) >
1282 TCP_PAWS_WINDOW) {
1283 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1284 goto drop_and_release;
1285 }
1286 }
1287 /* Kill the following clause, if you dislike this way. */
1288 else if (!sysctl_tcp_syncookies &&
1289 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1290 (sysctl_max_syn_backlog >> 2)) &&
1291 (!peer || !peer->tcp_ts_stamp) &&
1292 (!dst || !dst_metric(dst, RTAX_RTT))) {
1293 /* Without syncookies last quarter of
1294 * backlog is filled with destinations,
1295 * proven to be alive.
1296 * It means that we continue to communicate
1297 * to destinations, already remembered
1298 * to the moment of synflood.
1299 */
1300 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open "
1301 "request from " NIPQUAD_FMT "/%u\n",
1302 NIPQUAD(saddr),
1303 ntohs(tcp_hdr(skb)->source));
1304 goto drop_and_release;
1305 }
1306
1307 isn = tcp_v4_init_sequence(skb);
1308 }
1309 tcp_rsk(req)->snt_isn = isn;
1310
1311 if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
1312 goto drop_and_free;
1313
1314 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1315 return 0;
1316
1317 drop_and_release:
1318 dst_release(dst);
1319 drop_and_free:
1320 reqsk_free(req);
1321 drop:
1322 return 0;
1323 }
1324
1325
1326 /*
1327 * The three way handshake has completed - we got a valid synack -
1328 * now create the new socket.
1329 */
1330 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1331 struct request_sock *req,
1332 struct dst_entry *dst)
1333 {
1334 struct inet_request_sock *ireq;
1335 struct inet_sock *newinet;
1336 struct tcp_sock *newtp;
1337 struct sock *newsk;
1338 #ifdef CONFIG_TCP_MD5SIG
1339 struct tcp_md5sig_key *key;
1340 #endif
1341
1342 if (sk_acceptq_is_full(sk))
1343 goto exit_overflow;
1344
1345 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1346 goto exit;
1347
1348 newsk = tcp_create_openreq_child(sk, req, skb);
1349 if (!newsk)
1350 goto exit;
1351
1352 newsk->sk_gso_type = SKB_GSO_TCPV4;
1353 sk_setup_caps(newsk, dst);
1354
1355 newtp = tcp_sk(newsk);
1356 newinet = inet_sk(newsk);
1357 ireq = inet_rsk(req);
1358 newinet->daddr = ireq->rmt_addr;
1359 newinet->rcv_saddr = ireq->loc_addr;
1360 newinet->saddr = ireq->loc_addr;
1361 newinet->opt = ireq->opt;
1362 ireq->opt = NULL;
1363 newinet->mc_index = inet_iif(skb);
1364 newinet->mc_ttl = ip_hdr(skb)->ttl;
1365 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1366 if (newinet->opt)
1367 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1368 newinet->id = newtp->write_seq ^ jiffies;
1369
1370 tcp_mtup_init(newsk);
1371 tcp_sync_mss(newsk, dst_mtu(dst));
1372 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1373 tcp_initialize_rcv_mss(newsk);
1374
1375 #ifdef CONFIG_TCP_MD5SIG
1376 /* Copy over the MD5 key from the original socket */
1377 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
1378 /*
1379 * We're using one, so create a matching key
1380 * on the newsk structure. If we fail to get
1381 * memory, then we end up not copying the key
1382 * across. Shucks.
1383 */
1384 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1385 if (newkey != NULL)
1386 tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
1387 newkey, key->keylen);
1388 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1389 }
1390 #endif
1391
1392 __inet_hash_nolisten(newsk);
1393 __inet_inherit_port(sk, newsk);
1394
1395 return newsk;
1396
1397 exit_overflow:
1398 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1399 exit:
1400 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1401 dst_release(dst);
1402 return NULL;
1403 }
1404
1405 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1406 {
1407 struct tcphdr *th = tcp_hdr(skb);
1408 const struct iphdr *iph = ip_hdr(skb);
1409 struct sock *nsk;
1410 struct request_sock **prev;
1411 /* Find possible connection requests. */
1412 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1413 iph->saddr, iph->daddr);
1414 if (req)
1415 return tcp_check_req(sk, skb, req, prev);
1416
1417 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1418 th->source, iph->daddr, th->dest, inet_iif(skb));
1419
1420 if (nsk) {
1421 if (nsk->sk_state != TCP_TIME_WAIT) {
1422 bh_lock_sock(nsk);
1423 return nsk;
1424 }
1425 inet_twsk_put(inet_twsk(nsk));
1426 return NULL;
1427 }
1428
1429 #ifdef CONFIG_SYN_COOKIES
1430 if (!th->rst && !th->syn && th->ack)
1431 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1432 #endif
1433 return sk;
1434 }
1435
1436 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1437 {
1438 const struct iphdr *iph = ip_hdr(skb);
1439
1440 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1441 if (!tcp_v4_check(skb->len, iph->saddr,
1442 iph->daddr, skb->csum)) {
1443 skb->ip_summed = CHECKSUM_UNNECESSARY;
1444 return 0;
1445 }
1446 }
1447
1448 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1449 skb->len, IPPROTO_TCP, 0);
1450
1451 if (skb->len <= 76) {
1452 return __skb_checksum_complete(skb);
1453 }
1454 return 0;
1455 }
1456
1457
1458 /* The socket must have it's spinlock held when we get
1459 * here.
1460 *
1461 * We have a potential double-lock case here, so even when
1462 * doing backlog processing we use the BH locking scheme.
1463 * This is because we cannot sleep with the original spinlock
1464 * held.
1465 */
1466 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1467 {
1468 struct sock *rsk;
1469 #ifdef CONFIG_TCP_MD5SIG
1470 /*
1471 * We really want to reject the packet as early as possible
1472 * if:
1473 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1474 * o There is an MD5 option and we're not expecting one
1475 */
1476 if (tcp_v4_inbound_md5_hash(sk, skb))
1477 goto discard;
1478 #endif
1479
1480 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1481 TCP_CHECK_TIMER(sk);
1482 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1483 rsk = sk;
1484 goto reset;
1485 }
1486 TCP_CHECK_TIMER(sk);
1487 return 0;
1488 }
1489
1490 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1491 goto csum_err;
1492
1493 if (sk->sk_state == TCP_LISTEN) {
1494 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1495 if (!nsk)
1496 goto discard;
1497
1498 if (nsk != sk) {
1499 if (tcp_child_process(sk, nsk, skb)) {
1500 rsk = nsk;
1501 goto reset;
1502 }
1503 return 0;
1504 }
1505 }
1506
1507 TCP_CHECK_TIMER(sk);
1508 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1509 rsk = sk;
1510 goto reset;
1511 }
1512 TCP_CHECK_TIMER(sk);
1513 return 0;
1514
1515 reset:
1516 tcp_v4_send_reset(rsk, skb);
1517 discard:
1518 kfree_skb(skb);
1519 /* Be careful here. If this function gets more complicated and
1520 * gcc suffers from register pressure on the x86, sk (in %ebx)
1521 * might be destroyed here. This current version compiles correctly,
1522 * but you have been warned.
1523 */
1524 return 0;
1525
1526 csum_err:
1527 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1528 goto discard;
1529 }
1530
1531 /*
1532 * From tcp_input.c
1533 */
1534
1535 int tcp_v4_rcv(struct sk_buff *skb)
1536 {
1537 const struct iphdr *iph;
1538 struct tcphdr *th;
1539 struct sock *sk;
1540 int ret;
1541 struct net *net = dev_net(skb->dev);
1542
1543 if (skb->pkt_type != PACKET_HOST)
1544 goto discard_it;
1545
1546 /* Count it even if it's bad */
1547 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1548
1549 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1550 goto discard_it;
1551
1552 th = tcp_hdr(skb);
1553
1554 if (th->doff < sizeof(struct tcphdr) / 4)
1555 goto bad_packet;
1556 if (!pskb_may_pull(skb, th->doff * 4))
1557 goto discard_it;
1558
1559 /* An explanation is required here, I think.
1560 * Packet length and doff are validated by header prediction,
1561 * provided case of th->doff==0 is eliminated.
1562 * So, we defer the checks. */
1563 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1564 goto bad_packet;
1565
1566 th = tcp_hdr(skb);
1567 iph = ip_hdr(skb);
1568 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1569 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1570 skb->len - th->doff * 4);
1571 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1572 TCP_SKB_CB(skb)->when = 0;
1573 TCP_SKB_CB(skb)->flags = iph->tos;
1574 TCP_SKB_CB(skb)->sacked = 0;
1575
1576 sk = __inet_lookup(net, &tcp_hashinfo, iph->saddr,
1577 th->source, iph->daddr, th->dest, inet_iif(skb));
1578 if (!sk)
1579 goto no_tcp_socket;
1580
1581 process:
1582 if (sk->sk_state == TCP_TIME_WAIT)
1583 goto do_time_wait;
1584
1585 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1586 goto discard_and_relse;
1587 nf_reset(skb);
1588
1589 if (sk_filter(sk, skb))
1590 goto discard_and_relse;
1591
1592 skb->dev = NULL;
1593
1594 bh_lock_sock_nested(sk);
1595 ret = 0;
1596 if (!sock_owned_by_user(sk)) {
1597 #ifdef CONFIG_NET_DMA
1598 struct tcp_sock *tp = tcp_sk(sk);
1599 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1600 tp->ucopy.dma_chan = get_softnet_dma();
1601 if (tp->ucopy.dma_chan)
1602 ret = tcp_v4_do_rcv(sk, skb);
1603 else
1604 #endif
1605 {
1606 if (!tcp_prequeue(sk, skb))
1607 ret = tcp_v4_do_rcv(sk, skb);
1608 }
1609 } else
1610 sk_add_backlog(sk, skb);
1611 bh_unlock_sock(sk);
1612
1613 sock_put(sk);
1614
1615 return ret;
1616
1617 no_tcp_socket:
1618 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1619 goto discard_it;
1620
1621 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1622 bad_packet:
1623 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1624 } else {
1625 tcp_v4_send_reset(NULL, skb);
1626 }
1627
1628 discard_it:
1629 /* Discard frame. */
1630 kfree_skb(skb);
1631 return 0;
1632
1633 discard_and_relse:
1634 sock_put(sk);
1635 goto discard_it;
1636
1637 do_time_wait:
1638 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1639 inet_twsk_put(inet_twsk(sk));
1640 goto discard_it;
1641 }
1642
1643 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1644 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1645 inet_twsk_put(inet_twsk(sk));
1646 goto discard_it;
1647 }
1648 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1649 case TCP_TW_SYN: {
1650 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1651 &tcp_hashinfo,
1652 iph->daddr, th->dest,
1653 inet_iif(skb));
1654 if (sk2) {
1655 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1656 inet_twsk_put(inet_twsk(sk));
1657 sk = sk2;
1658 goto process;
1659 }
1660 /* Fall through to ACK */
1661 }
1662 case TCP_TW_ACK:
1663 tcp_v4_timewait_ack(sk, skb);
1664 break;
1665 case TCP_TW_RST:
1666 goto no_tcp_socket;
1667 case TCP_TW_SUCCESS:;
1668 }
1669 goto discard_it;
1670 }
1671
1672 /* VJ's idea. Save last timestamp seen from this destination
1673 * and hold it at least for normal timewait interval to use for duplicate
1674 * segment detection in subsequent connections, before they enter synchronized
1675 * state.
1676 */
1677
1678 int tcp_v4_remember_stamp(struct sock *sk)
1679 {
1680 struct inet_sock *inet = inet_sk(sk);
1681 struct tcp_sock *tp = tcp_sk(sk);
1682 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1683 struct inet_peer *peer = NULL;
1684 int release_it = 0;
1685
1686 if (!rt || rt->rt_dst != inet->daddr) {
1687 peer = inet_getpeer(inet->daddr, 1);
1688 release_it = 1;
1689 } else {
1690 if (!rt->peer)
1691 rt_bind_peer(rt, 1);
1692 peer = rt->peer;
1693 }
1694
1695 if (peer) {
1696 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1697 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1698 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1699 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1700 peer->tcp_ts = tp->rx_opt.ts_recent;
1701 }
1702 if (release_it)
1703 inet_putpeer(peer);
1704 return 1;
1705 }
1706
1707 return 0;
1708 }
1709
1710 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1711 {
1712 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1713
1714 if (peer) {
1715 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1716
1717 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1718 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1719 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1720 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1721 peer->tcp_ts = tcptw->tw_ts_recent;
1722 }
1723 inet_putpeer(peer);
1724 return 1;
1725 }
1726
1727 return 0;
1728 }
1729
1730 struct inet_connection_sock_af_ops ipv4_specific = {
1731 .queue_xmit = ip_queue_xmit,
1732 .send_check = tcp_v4_send_check,
1733 .rebuild_header = inet_sk_rebuild_header,
1734 .conn_request = tcp_v4_conn_request,
1735 .syn_recv_sock = tcp_v4_syn_recv_sock,
1736 .remember_stamp = tcp_v4_remember_stamp,
1737 .net_header_len = sizeof(struct iphdr),
1738 .setsockopt = ip_setsockopt,
1739 .getsockopt = ip_getsockopt,
1740 .addr2sockaddr = inet_csk_addr2sockaddr,
1741 .sockaddr_len = sizeof(struct sockaddr_in),
1742 .bind_conflict = inet_csk_bind_conflict,
1743 #ifdef CONFIG_COMPAT
1744 .compat_setsockopt = compat_ip_setsockopt,
1745 .compat_getsockopt = compat_ip_getsockopt,
1746 #endif
1747 };
1748
1749 #ifdef CONFIG_TCP_MD5SIG
1750 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1751 .md5_lookup = tcp_v4_md5_lookup,
1752 .calc_md5_hash = tcp_v4_md5_hash_skb,
1753 .md5_add = tcp_v4_md5_add_func,
1754 .md5_parse = tcp_v4_parse_md5_keys,
1755 };
1756 #endif
1757
1758 /* NOTE: A lot of things set to zero explicitly by call to
1759 * sk_alloc() so need not be done here.
1760 */
1761 static int tcp_v4_init_sock(struct sock *sk)
1762 {
1763 struct inet_connection_sock *icsk = inet_csk(sk);
1764 struct tcp_sock *tp = tcp_sk(sk);
1765
1766 skb_queue_head_init(&tp->out_of_order_queue);
1767 tcp_init_xmit_timers(sk);
1768 tcp_prequeue_init(tp);
1769
1770 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1771 tp->mdev = TCP_TIMEOUT_INIT;
1772
1773 /* So many TCP implementations out there (incorrectly) count the
1774 * initial SYN frame in their delayed-ACK and congestion control
1775 * algorithms that we must have the following bandaid to talk
1776 * efficiently to them. -DaveM
1777 */
1778 tp->snd_cwnd = 2;
1779
1780 /* See draft-stevens-tcpca-spec-01 for discussion of the
1781 * initialization of these values.
1782 */
1783 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1784 tp->snd_cwnd_clamp = ~0;
1785 tp->mss_cache = 536;
1786
1787 tp->reordering = sysctl_tcp_reordering;
1788 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1789
1790 sk->sk_state = TCP_CLOSE;
1791
1792 sk->sk_write_space = sk_stream_write_space;
1793 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1794
1795 icsk->icsk_af_ops = &ipv4_specific;
1796 icsk->icsk_sync_mss = tcp_sync_mss;
1797 #ifdef CONFIG_TCP_MD5SIG
1798 tp->af_specific = &tcp_sock_ipv4_specific;
1799 #endif
1800
1801 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1802 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1803
1804 atomic_inc(&tcp_sockets_allocated);
1805
1806 return 0;
1807 }
1808
1809 void tcp_v4_destroy_sock(struct sock *sk)
1810 {
1811 struct tcp_sock *tp = tcp_sk(sk);
1812
1813 tcp_clear_xmit_timers(sk);
1814
1815 tcp_cleanup_congestion_control(sk);
1816
1817 /* Cleanup up the write buffer. */
1818 tcp_write_queue_purge(sk);
1819
1820 /* Cleans up our, hopefully empty, out_of_order_queue. */
1821 __skb_queue_purge(&tp->out_of_order_queue);
1822
1823 #ifdef CONFIG_TCP_MD5SIG
1824 /* Clean up the MD5 key list, if any */
1825 if (tp->md5sig_info) {
1826 tcp_v4_clear_md5_list(sk);
1827 kfree(tp->md5sig_info);
1828 tp->md5sig_info = NULL;
1829 }
1830 #endif
1831
1832 #ifdef CONFIG_NET_DMA
1833 /* Cleans up our sk_async_wait_queue */
1834 __skb_queue_purge(&sk->sk_async_wait_queue);
1835 #endif
1836
1837 /* Clean prequeue, it must be empty really */
1838 __skb_queue_purge(&tp->ucopy.prequeue);
1839
1840 /* Clean up a referenced TCP bind bucket. */
1841 if (inet_csk(sk)->icsk_bind_hash)
1842 inet_put_port(sk);
1843
1844 /*
1845 * If sendmsg cached page exists, toss it.
1846 */
1847 if (sk->sk_sndmsg_page) {
1848 __free_page(sk->sk_sndmsg_page);
1849 sk->sk_sndmsg_page = NULL;
1850 }
1851
1852 atomic_dec(&tcp_sockets_allocated);
1853 }
1854
1855 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1856
1857 #ifdef CONFIG_PROC_FS
1858 /* Proc filesystem TCP sock list dumping. */
1859
1860 static inline struct inet_timewait_sock *tw_head(struct hlist_head *head)
1861 {
1862 return hlist_empty(head) ? NULL :
1863 list_entry(head->first, struct inet_timewait_sock, tw_node);
1864 }
1865
1866 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1867 {
1868 return tw->tw_node.next ?
1869 hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1870 }
1871
1872 static void *listening_get_next(struct seq_file *seq, void *cur)
1873 {
1874 struct inet_connection_sock *icsk;
1875 struct hlist_node *node;
1876 struct sock *sk = cur;
1877 struct tcp_iter_state* st = seq->private;
1878 struct net *net = seq_file_net(seq);
1879
1880 if (!sk) {
1881 st->bucket = 0;
1882 sk = sk_head(&tcp_hashinfo.listening_hash[0]);
1883 goto get_sk;
1884 }
1885
1886 ++st->num;
1887
1888 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1889 struct request_sock *req = cur;
1890
1891 icsk = inet_csk(st->syn_wait_sk);
1892 req = req->dl_next;
1893 while (1) {
1894 while (req) {
1895 if (req->rsk_ops->family == st->family &&
1896 net_eq(sock_net(req->sk), net)) {
1897 cur = req;
1898 goto out;
1899 }
1900 req = req->dl_next;
1901 }
1902 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1903 break;
1904 get_req:
1905 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1906 }
1907 sk = sk_next(st->syn_wait_sk);
1908 st->state = TCP_SEQ_STATE_LISTENING;
1909 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1910 } else {
1911 icsk = inet_csk(sk);
1912 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1913 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1914 goto start_req;
1915 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1916 sk = sk_next(sk);
1917 }
1918 get_sk:
1919 sk_for_each_from(sk, node) {
1920 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
1921 cur = sk;
1922 goto out;
1923 }
1924 icsk = inet_csk(sk);
1925 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1926 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1927 start_req:
1928 st->uid = sock_i_uid(sk);
1929 st->syn_wait_sk = sk;
1930 st->state = TCP_SEQ_STATE_OPENREQ;
1931 st->sbucket = 0;
1932 goto get_req;
1933 }
1934 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1935 }
1936 if (++st->bucket < INET_LHTABLE_SIZE) {
1937 sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
1938 goto get_sk;
1939 }
1940 cur = NULL;
1941 out:
1942 return cur;
1943 }
1944
1945 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1946 {
1947 void *rc = listening_get_next(seq, NULL);
1948
1949 while (rc && *pos) {
1950 rc = listening_get_next(seq, rc);
1951 --*pos;
1952 }
1953 return rc;
1954 }
1955
1956 static void *established_get_first(struct seq_file *seq)
1957 {
1958 struct tcp_iter_state* st = seq->private;
1959 struct net *net = seq_file_net(seq);
1960 void *rc = NULL;
1961
1962 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1963 struct sock *sk;
1964 struct hlist_node *node;
1965 struct inet_timewait_sock *tw;
1966 rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1967
1968 read_lock_bh(lock);
1969 sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1970 if (sk->sk_family != st->family ||
1971 !net_eq(sock_net(sk), net)) {
1972 continue;
1973 }
1974 rc = sk;
1975 goto out;
1976 }
1977 st->state = TCP_SEQ_STATE_TIME_WAIT;
1978 inet_twsk_for_each(tw, node,
1979 &tcp_hashinfo.ehash[st->bucket].twchain) {
1980 if (tw->tw_family != st->family ||
1981 !net_eq(twsk_net(tw), net)) {
1982 continue;
1983 }
1984 rc = tw;
1985 goto out;
1986 }
1987 read_unlock_bh(lock);
1988 st->state = TCP_SEQ_STATE_ESTABLISHED;
1989 }
1990 out:
1991 return rc;
1992 }
1993
1994 static void *established_get_next(struct seq_file *seq, void *cur)
1995 {
1996 struct sock *sk = cur;
1997 struct inet_timewait_sock *tw;
1998 struct hlist_node *node;
1999 struct tcp_iter_state* st = seq->private;
2000 struct net *net = seq_file_net(seq);
2001
2002 ++st->num;
2003
2004 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2005 tw = cur;
2006 tw = tw_next(tw);
2007 get_tw:
2008 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2009 tw = tw_next(tw);
2010 }
2011 if (tw) {
2012 cur = tw;
2013 goto out;
2014 }
2015 read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2016 st->state = TCP_SEQ_STATE_ESTABLISHED;
2017
2018 if (++st->bucket < tcp_hashinfo.ehash_size) {
2019 read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2020 sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain);
2021 } else {
2022 cur = NULL;
2023 goto out;
2024 }
2025 } else
2026 sk = sk_next(sk);
2027
2028 sk_for_each_from(sk, node) {
2029 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2030 goto found;
2031 }
2032
2033 st->state = TCP_SEQ_STATE_TIME_WAIT;
2034 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2035 goto get_tw;
2036 found:
2037 cur = sk;
2038 out:
2039 return cur;
2040 }
2041
2042 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2043 {
2044 void *rc = established_get_first(seq);
2045
2046 while (rc && pos) {
2047 rc = established_get_next(seq, rc);
2048 --pos;
2049 }
2050 return rc;
2051 }
2052
2053 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2054 {
2055 void *rc;
2056 struct tcp_iter_state* st = seq->private;
2057
2058 inet_listen_lock(&tcp_hashinfo);
2059 st->state = TCP_SEQ_STATE_LISTENING;
2060 rc = listening_get_idx(seq, &pos);
2061
2062 if (!rc) {
2063 inet_listen_unlock(&tcp_hashinfo);
2064 st->state = TCP_SEQ_STATE_ESTABLISHED;
2065 rc = established_get_idx(seq, pos);
2066 }
2067
2068 return rc;
2069 }
2070
2071 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2072 {
2073 struct tcp_iter_state* st = seq->private;
2074 st->state = TCP_SEQ_STATE_LISTENING;
2075 st->num = 0;
2076 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2077 }
2078
2079 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2080 {
2081 void *rc = NULL;
2082 struct tcp_iter_state* st;
2083
2084 if (v == SEQ_START_TOKEN) {
2085 rc = tcp_get_idx(seq, 0);
2086 goto out;
2087 }
2088 st = seq->private;
2089
2090 switch (st->state) {
2091 case TCP_SEQ_STATE_OPENREQ:
2092 case TCP_SEQ_STATE_LISTENING:
2093 rc = listening_get_next(seq, v);
2094 if (!rc) {
2095 inet_listen_unlock(&tcp_hashinfo);
2096 st->state = TCP_SEQ_STATE_ESTABLISHED;
2097 rc = established_get_first(seq);
2098 }
2099 break;
2100 case TCP_SEQ_STATE_ESTABLISHED:
2101 case TCP_SEQ_STATE_TIME_WAIT:
2102 rc = established_get_next(seq, v);
2103 break;
2104 }
2105 out:
2106 ++*pos;
2107 return rc;
2108 }
2109
2110 static void tcp_seq_stop(struct seq_file *seq, void *v)
2111 {
2112 struct tcp_iter_state* st = seq->private;
2113
2114 switch (st->state) {
2115 case TCP_SEQ_STATE_OPENREQ:
2116 if (v) {
2117 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2118 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2119 }
2120 case TCP_SEQ_STATE_LISTENING:
2121 if (v != SEQ_START_TOKEN)
2122 inet_listen_unlock(&tcp_hashinfo);
2123 break;
2124 case TCP_SEQ_STATE_TIME_WAIT:
2125 case TCP_SEQ_STATE_ESTABLISHED:
2126 if (v)
2127 read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2128 break;
2129 }
2130 }
2131
2132 static int tcp_seq_open(struct inode *inode, struct file *file)
2133 {
2134 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2135 struct tcp_iter_state *s;
2136 int err;
2137
2138 err = seq_open_net(inode, file, &afinfo->seq_ops,
2139 sizeof(struct tcp_iter_state));
2140 if (err < 0)
2141 return err;
2142
2143 s = ((struct seq_file *)file->private_data)->private;
2144 s->family = afinfo->family;
2145 return 0;
2146 }
2147
2148 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2149 {
2150 int rc = 0;
2151 struct proc_dir_entry *p;
2152
2153 afinfo->seq_fops.open = tcp_seq_open;
2154 afinfo->seq_fops.read = seq_read;
2155 afinfo->seq_fops.llseek = seq_lseek;
2156 afinfo->seq_fops.release = seq_release_net;
2157
2158 afinfo->seq_ops.start = tcp_seq_start;
2159 afinfo->seq_ops.next = tcp_seq_next;
2160 afinfo->seq_ops.stop = tcp_seq_stop;
2161
2162 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2163 &afinfo->seq_fops, afinfo);
2164 if (!p)
2165 rc = -ENOMEM;
2166 return rc;
2167 }
2168
2169 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2170 {
2171 proc_net_remove(net, afinfo->name);
2172 }
2173
2174 static void get_openreq4(struct sock *sk, struct request_sock *req,
2175 struct seq_file *f, int i, int uid, int *len)
2176 {
2177 const struct inet_request_sock *ireq = inet_rsk(req);
2178 int ttd = req->expires - jiffies;
2179
2180 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2181 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
2182 i,
2183 ireq->loc_addr,
2184 ntohs(inet_sk(sk)->sport),
2185 ireq->rmt_addr,
2186 ntohs(ireq->rmt_port),
2187 TCP_SYN_RECV,
2188 0, 0, /* could print option size, but that is af dependent. */
2189 1, /* timers active (only the expire timer) */
2190 jiffies_to_clock_t(ttd),
2191 req->retrans,
2192 uid,
2193 0, /* non standard timer */
2194 0, /* open_requests have no inode */
2195 atomic_read(&sk->sk_refcnt),
2196 req,
2197 len);
2198 }
2199
2200 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2201 {
2202 int timer_active;
2203 unsigned long timer_expires;
2204 struct tcp_sock *tp = tcp_sk(sk);
2205 const struct inet_connection_sock *icsk = inet_csk(sk);
2206 struct inet_sock *inet = inet_sk(sk);
2207 __be32 dest = inet->daddr;
2208 __be32 src = inet->rcv_saddr;
2209 __u16 destp = ntohs(inet->dport);
2210 __u16 srcp = ntohs(inet->sport);
2211
2212 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2213 timer_active = 1;
2214 timer_expires = icsk->icsk_timeout;
2215 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2216 timer_active = 4;
2217 timer_expires = icsk->icsk_timeout;
2218 } else if (timer_pending(&sk->sk_timer)) {
2219 timer_active = 2;
2220 timer_expires = sk->sk_timer.expires;
2221 } else {
2222 timer_active = 0;
2223 timer_expires = jiffies;
2224 }
2225
2226 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2227 "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2228 i, src, srcp, dest, destp, sk->sk_state,
2229 tp->write_seq - tp->snd_una,
2230 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2231 (tp->rcv_nxt - tp->copied_seq),
2232 timer_active,
2233 jiffies_to_clock_t(timer_expires - jiffies),
2234 icsk->icsk_retransmits,
2235 sock_i_uid(sk),
2236 icsk->icsk_probes_out,
2237 sock_i_ino(sk),
2238 atomic_read(&sk->sk_refcnt), sk,
2239 jiffies_to_clock_t(icsk->icsk_rto),
2240 jiffies_to_clock_t(icsk->icsk_ack.ato),
2241 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2242 tp->snd_cwnd,
2243 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh,
2244 len);
2245 }
2246
2247 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2248 struct seq_file *f, int i, int *len)
2249 {
2250 __be32 dest, src;
2251 __u16 destp, srcp;
2252 int ttd = tw->tw_ttd - jiffies;
2253
2254 if (ttd < 0)
2255 ttd = 0;
2256
2257 dest = tw->tw_daddr;
2258 src = tw->tw_rcv_saddr;
2259 destp = ntohs(tw->tw_dport);
2260 srcp = ntohs(tw->tw_sport);
2261
2262 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2263 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
2264 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2265 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2266 atomic_read(&tw->tw_refcnt), tw, len);
2267 }
2268
2269 #define TMPSZ 150
2270
2271 static int tcp4_seq_show(struct seq_file *seq, void *v)
2272 {
2273 struct tcp_iter_state* st;
2274 int len;
2275
2276 if (v == SEQ_START_TOKEN) {
2277 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2278 " sl local_address rem_address st tx_queue "
2279 "rx_queue tr tm->when retrnsmt uid timeout "
2280 "inode");
2281 goto out;
2282 }
2283 st = seq->private;
2284
2285 switch (st->state) {
2286 case TCP_SEQ_STATE_LISTENING:
2287 case TCP_SEQ_STATE_ESTABLISHED:
2288 get_tcp4_sock(v, seq, st->num, &len);
2289 break;
2290 case TCP_SEQ_STATE_OPENREQ:
2291 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2292 break;
2293 case TCP_SEQ_STATE_TIME_WAIT:
2294 get_timewait4_sock(v, seq, st->num, &len);
2295 break;
2296 }
2297 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2298 out:
2299 return 0;
2300 }
2301
2302 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2303 .name = "tcp",
2304 .family = AF_INET,
2305 .seq_fops = {
2306 .owner = THIS_MODULE,
2307 },
2308 .seq_ops = {
2309 .show = tcp4_seq_show,
2310 },
2311 };
2312
2313 static int tcp4_proc_init_net(struct net *net)
2314 {
2315 return tcp_proc_register(net, &tcp4_seq_afinfo);
2316 }
2317
2318 static void tcp4_proc_exit_net(struct net *net)
2319 {
2320 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2321 }
2322
2323 static struct pernet_operations tcp4_net_ops = {
2324 .init = tcp4_proc_init_net,
2325 .exit = tcp4_proc_exit_net,
2326 };
2327
2328 int __init tcp4_proc_init(void)
2329 {
2330 return register_pernet_subsys(&tcp4_net_ops);
2331 }
2332
2333 void tcp4_proc_exit(void)
2334 {
2335 unregister_pernet_subsys(&tcp4_net_ops);
2336 }
2337 #endif /* CONFIG_PROC_FS */
2338
2339 struct proto tcp_prot = {
2340 .name = "TCP",
2341 .owner = THIS_MODULE,
2342 .close = tcp_close,
2343 .connect = tcp_v4_connect,
2344 .disconnect = tcp_disconnect,
2345 .accept = inet_csk_accept,
2346 .ioctl = tcp_ioctl,
2347 .init = tcp_v4_init_sock,
2348 .destroy = tcp_v4_destroy_sock,
2349 .shutdown = tcp_shutdown,
2350 .setsockopt = tcp_setsockopt,
2351 .getsockopt = tcp_getsockopt,
2352 .recvmsg = tcp_recvmsg,
2353 .backlog_rcv = tcp_v4_do_rcv,
2354 .hash = inet_hash,
2355 .unhash = inet_unhash,
2356 .get_port = inet_csk_get_port,
2357 .enter_memory_pressure = tcp_enter_memory_pressure,
2358 .sockets_allocated = &tcp_sockets_allocated,
2359 .orphan_count = &tcp_orphan_count,
2360 .memory_allocated = &tcp_memory_allocated,
2361 .memory_pressure = &tcp_memory_pressure,
2362 .sysctl_mem = sysctl_tcp_mem,
2363 .sysctl_wmem = sysctl_tcp_wmem,
2364 .sysctl_rmem = sysctl_tcp_rmem,
2365 .max_header = MAX_TCP_HEADER,
2366 .obj_size = sizeof(struct tcp_sock),
2367 .twsk_prot = &tcp_timewait_sock_ops,
2368 .rsk_prot = &tcp_request_sock_ops,
2369 .h.hashinfo = &tcp_hashinfo,
2370 #ifdef CONFIG_COMPAT
2371 .compat_setsockopt = compat_tcp_setsockopt,
2372 .compat_getsockopt = compat_tcp_getsockopt,
2373 #endif
2374 };
2375
2376
2377 static int __net_init tcp_sk_init(struct net *net)
2378 {
2379 return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2380 PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2381 }
2382
2383 static void __net_exit tcp_sk_exit(struct net *net)
2384 {
2385 inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2386 }
2387
2388 static struct pernet_operations __net_initdata tcp_sk_ops = {
2389 .init = tcp_sk_init,
2390 .exit = tcp_sk_exit,
2391 };
2392
2393 void __init tcp_v4_init(void)
2394 {
2395 if (register_pernet_device(&tcp_sk_ops))
2396 panic("Failed to create the TCP control socket.\n");
2397 }
2398
2399 EXPORT_SYMBOL(ipv4_specific);
2400 EXPORT_SYMBOL(tcp_hashinfo);
2401 EXPORT_SYMBOL(tcp_prot);
2402 EXPORT_SYMBOL(tcp_v4_conn_request);
2403 EXPORT_SYMBOL(tcp_v4_connect);
2404 EXPORT_SYMBOL(tcp_v4_do_rcv);
2405 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2406 EXPORT_SYMBOL(tcp_v4_send_check);
2407 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2408
2409 #ifdef CONFIG_PROC_FS
2410 EXPORT_SYMBOL(tcp_proc_register);
2411 EXPORT_SYMBOL(tcp_proc_unregister);
2412 #endif
2413 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2414
Linux kernel - Deliverables
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