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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt...
[linux-2.6/mini2440.git] / net / ipv4 / tcp_ipv4.c
blob6d88219c5e22bd4bf752a543bebfb5af4ae36a1f
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Implementation of the Transmission Control Protocol(TCP).
7 *
8 * IPv4 specific functions
9 *
10 *
11 * code split from:
12 * linux/ipv4/tcp.c
13 * linux/ipv4/tcp_input.c
14 * linux/ipv4/tcp_output.c
15 *
16 * See tcp.c for author information
17 *
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
22 */
23
24 /*
25 * Changes:
26 * David S. Miller : New socket lookup architecture.
27 * This code is dedicated to John Dyson.
28 * David S. Miller : Change semantics of established hash,
29 * half is devoted to TIME_WAIT sockets
30 * and the rest go in the other half.
31 * Andi Kleen : Add support for syncookies and fixed
32 * some bugs: ip options weren't passed to
33 * the TCP layer, missed a check for an
34 * ACK bit.
35 * Andi Kleen : Implemented fast path mtu discovery.
36 * Fixed many serious bugs in the
37 * request_sock handling and moved
38 * most of it into the af independent code.
39 * Added tail drop and some other bugfixes.
40 * Added new listen semantics.
41 * Mike McLagan : Routing by source
42 * Juan Jose Ciarlante: ip_dynaddr bits
43 * Andi Kleen: various fixes.
44 * Vitaly E. Lavrov : Transparent proxy revived after year
45 * coma.
46 * Andi Kleen : Fix new listen.
47 * Andi Kleen : Fix accept error reporting.
48 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which
49 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind
50 * a single port at the same time.
51 */
52
53
54 #include <linux/bottom_half.h>
55 #include <linux/types.h>
56 #include <linux/fcntl.h>
57 #include <linux/module.h>
58 #include <linux/random.h>
59 #include <linux/cache.h>
60 #include <linux/jhash.h>
61 #include <linux/init.h>
62 #include <linux/times.h>
63
64 #include <net/net_namespace.h>
65 #include <net/icmp.h>
66 #include <net/inet_hashtables.h>
67 #include <net/tcp.h>
68 #include <net/transp_v6.h>
69 #include <net/ipv6.h>
70 #include <net/inet_common.h>
71 #include <net/timewait_sock.h>
72 #include <net/xfrm.h>
73 #include <net/netdma.h>
74
75 #include <linux/inet.h>
76 #include <linux/ipv6.h>
77 #include <linux/stddef.h>
78 #include <linux/proc_fs.h>
79 #include <linux/seq_file.h>
80
81 #include <linux/crypto.h>
82 #include <linux/scatterlist.h>
83
84 int sysctl_tcp_tw_reuse __read_mostly;
85 int sysctl_tcp_low_latency __read_mostly;
86
87
88 #ifdef CONFIG_TCP_MD5SIG
89 static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
90 __be32 addr);
91 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
92 __be32 daddr, __be32 saddr, struct tcphdr *th);
93 #else
94 static inline
95 struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
96 {
97 return NULL;
98 }
99 #endif
100
101 struct inet_hashinfo tcp_hashinfo;
102
103 static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
104 {
105 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
106 ip_hdr(skb)->saddr,
107 tcp_hdr(skb)->dest,
108 tcp_hdr(skb)->source);
109 }
110
111 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
112 {
113 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
114 struct tcp_sock *tp = tcp_sk(sk);
115
116 /* With PAWS, it is safe from the viewpoint
117 of data integrity. Even without PAWS it is safe provided sequence
118 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
119
120 Actually, the idea is close to VJ's one, only timestamp cache is
121 held not per host, but per port pair and TW bucket is used as state
122 holder.
123
124 If TW bucket has been already destroyed we fall back to VJ's scheme
125 and use initial timestamp retrieved from peer table.
126 */
127 if (tcptw->tw_ts_recent_stamp &&
128 (twp == NULL || (sysctl_tcp_tw_reuse &&
129 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
130 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
131 if (tp->write_seq == 0)
132 tp->write_seq = 1;
133 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
134 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
135 sock_hold(sktw);
136 return 1;
137 }
138
139 return 0;
140 }
141
142 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
143
144 /* This will initiate an outgoing connection. */
145 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
146 {
147 struct inet_sock *inet = inet_sk(sk);
148 struct tcp_sock *tp = tcp_sk(sk);
149 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
150 struct rtable *rt;
151 __be32 daddr, nexthop;
152 int tmp;
153 int err;
154
155 if (addr_len < sizeof(struct sockaddr_in))
156 return -EINVAL;
157
158 if (usin->sin_family != AF_INET)
159 return -EAFNOSUPPORT;
160
161 nexthop = daddr = usin->sin_addr.s_addr;
162 if (inet->opt && inet->opt->srr) {
163 if (!daddr)
164 return -EINVAL;
165 nexthop = inet->opt->faddr;
166 }
167
168 tmp = ip_route_connect(&rt, nexthop, inet->saddr,
169 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
170 IPPROTO_TCP,
171 inet->sport, usin->sin_port, sk, 1);
172 if (tmp < 0) {
173 if (tmp == -ENETUNREACH)
174 IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
175 return tmp;
176 }
177
178 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
179 ip_rt_put(rt);
180 return -ENETUNREACH;
181 }
182
183 if (!inet->opt || !inet->opt->srr)
184 daddr = rt->rt_dst;
185
186 if (!inet->saddr)
187 inet->saddr = rt->rt_src;
188 inet->rcv_saddr = inet->saddr;
189
190 if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
191 /* Reset inherited state */
192 tp->rx_opt.ts_recent = 0;
193 tp->rx_opt.ts_recent_stamp = 0;
194 tp->write_seq = 0;
195 }
196
197 if (tcp_death_row.sysctl_tw_recycle &&
198 !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
199 struct inet_peer *peer = rt_get_peer(rt);
200 /*
201 * VJ's idea. We save last timestamp seen from
202 * the destination in peer table, when entering state
203 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
204 * when trying new connection.
205 */
206 if (peer != NULL &&
207 peer->tcp_ts_stamp + TCP_PAWS_MSL >= get_seconds()) {
208 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
209 tp->rx_opt.ts_recent = peer->tcp_ts;
210 }
211 }
212
213 inet->dport = usin->sin_port;
214 inet->daddr = daddr;
215
216 inet_csk(sk)->icsk_ext_hdr_len = 0;
217 if (inet->opt)
218 inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
219
220 tp->rx_opt.mss_clamp = 536;
221
222 /* Socket identity is still unknown (sport may be zero).
223 * However we set state to SYN-SENT and not releasing socket
224 * lock select source port, enter ourselves into the hash tables and
225 * complete initialization after this.
226 */
227 tcp_set_state(sk, TCP_SYN_SENT);
228 err = inet_hash_connect(&tcp_death_row, sk);
229 if (err)
230 goto failure;
231
232 err = ip_route_newports(&rt, IPPROTO_TCP,
233 inet->sport, inet->dport, sk);
234 if (err)
235 goto failure;
236
237 /* OK, now commit destination to socket. */
238 sk->sk_gso_type = SKB_GSO_TCPV4;
239 sk_setup_caps(sk, &rt->u.dst);
240
241 if (!tp->write_seq)
242 tp->write_seq = secure_tcp_sequence_number(inet->saddr,
243 inet->daddr,
244 inet->sport,
245 usin->sin_port);
246
247 inet->id = tp->write_seq ^ jiffies;
248
249 err = tcp_connect(sk);
250 rt = NULL;
251 if (err)
252 goto failure;
253
254 return 0;
255
256 failure:
257 /*
258 * This unhashes the socket and releases the local port,
259 * if necessary.
260 */
261 tcp_set_state(sk, TCP_CLOSE);
262 ip_rt_put(rt);
263 sk->sk_route_caps = 0;
264 inet->dport = 0;
265 return err;
266 }
267
268 /*
269 * This routine does path mtu discovery as defined in RFC1191.
270 */
271 static void do_pmtu_discovery(struct sock *sk, struct iphdr *iph, u32 mtu)
272 {
273 struct dst_entry *dst;
274 struct inet_sock *inet = inet_sk(sk);
275
276 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
277 * send out by Linux are always <576bytes so they should go through
278 * unfragmented).
279 */
280 if (sk->sk_state == TCP_LISTEN)
281 return;
282
283 /* We don't check in the destentry if pmtu discovery is forbidden
284 * on this route. We just assume that no packet_to_big packets
285 * are send back when pmtu discovery is not active.
286 * There is a small race when the user changes this flag in the
287 * route, but I think that's acceptable.
288 */
289 if ((dst = __sk_dst_check(sk, 0)) == NULL)
290 return;
291
292 dst->ops->update_pmtu(dst, mtu);
293
294 /* Something is about to be wrong... Remember soft error
295 * for the case, if this connection will not able to recover.
296 */
297 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
298 sk->sk_err_soft = EMSGSIZE;
299
300 mtu = dst_mtu(dst);
301
302 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
303 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
304 tcp_sync_mss(sk, mtu);
305
306 /* Resend the TCP packet because it's
307 * clear that the old packet has been
308 * dropped. This is the new "fast" path mtu
309 * discovery.
310 */
311 tcp_simple_retransmit(sk);
312 } /* else let the usual retransmit timer handle it */
313 }
314
315 /*
316 * This routine is called by the ICMP module when it gets some
317 * sort of error condition. If err < 0 then the socket should
318 * be closed and the error returned to the user. If err > 0
319 * it's just the icmp type << 8 | icmp code. After adjustment
320 * header points to the first 8 bytes of the tcp header. We need
321 * to find the appropriate port.
322 *
323 * The locking strategy used here is very "optimistic". When
324 * someone else accesses the socket the ICMP is just dropped
325 * and for some paths there is no check at all.
326 * A more general error queue to queue errors for later handling
327 * is probably better.
328 *
329 */
330
331 void tcp_v4_err(struct sk_buff *skb, u32 info)
332 {
333 struct iphdr *iph = (struct iphdr *)skb->data;
334 struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
335 struct tcp_sock *tp;
336 struct inet_sock *inet;
337 const int type = icmp_hdr(skb)->type;
338 const int code = icmp_hdr(skb)->code;
339 struct sock *sk;
340 __u32 seq;
341 int err;
342 struct net *net = dev_net(skb->dev);
343
344 if (skb->len < (iph->ihl << 2) + 8) {
345 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
346 return;
347 }
348
349 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
350 iph->saddr, th->source, inet_iif(skb));
351 if (!sk) {
352 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
353 return;
354 }
355 if (sk->sk_state == TCP_TIME_WAIT) {
356 inet_twsk_put(inet_twsk(sk));
357 return;
358 }
359
360 bh_lock_sock(sk);
361 /* If too many ICMPs get dropped on busy
362 * servers this needs to be solved differently.
363 */
364 if (sock_owned_by_user(sk))
365 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
366
367 if (sk->sk_state == TCP_CLOSE)
368 goto out;
369
370 tp = tcp_sk(sk);
371 seq = ntohl(th->seq);
372 if (sk->sk_state != TCP_LISTEN &&
373 !between(seq, tp->snd_una, tp->snd_nxt)) {
374 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
375 goto out;
376 }
377
378 switch (type) {
379 case ICMP_SOURCE_QUENCH:
380 /* Just silently ignore these. */
381 goto out;
382 case ICMP_PARAMETERPROB:
383 err = EPROTO;
384 break;
385 case ICMP_DEST_UNREACH:
386 if (code > NR_ICMP_UNREACH)
387 goto out;
388
389 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
390 if (!sock_owned_by_user(sk))
391 do_pmtu_discovery(sk, iph, info);
392 goto out;
393 }
394
395 err = icmp_err_convert[code].errno;
396 break;
397 case ICMP_TIME_EXCEEDED:
398 err = EHOSTUNREACH;
399 break;
400 default:
401 goto out;
402 }
403
404 switch (sk->sk_state) {
405 struct request_sock *req, **prev;
406 case TCP_LISTEN:
407 if (sock_owned_by_user(sk))
408 goto out;
409
410 req = inet_csk_search_req(sk, &prev, th->dest,
411 iph->daddr, iph->saddr);
412 if (!req)
413 goto out;
414
415 /* ICMPs are not backlogged, hence we cannot get
416 an established socket here.
417 */
418 WARN_ON(req->sk);
419
420 if (seq != tcp_rsk(req)->snt_isn) {
421 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
422 goto out;
423 }
424
425 /*
426 * Still in SYN_RECV, just remove it silently.
427 * There is no good way to pass the error to the newly
428 * created socket, and POSIX does not want network
429 * errors returned from accept().
430 */
431 inet_csk_reqsk_queue_drop(sk, req, prev);
432 goto out;
433
434 case TCP_SYN_SENT:
435 case TCP_SYN_RECV: /* Cannot happen.
436 It can f.e. if SYNs crossed.
437 */
438 if (!sock_owned_by_user(sk)) {
439 sk->sk_err = err;
440
441 sk->sk_error_report(sk);
442
443 tcp_done(sk);
444 } else {
445 sk->sk_err_soft = err;
446 }
447 goto out;
448 }
449
450 /* If we've already connected we will keep trying
451 * until we time out, or the user gives up.
452 *
453 * rfc1122 4.2.3.9 allows to consider as hard errors
454 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
455 * but it is obsoleted by pmtu discovery).
456 *
457 * Note, that in modern internet, where routing is unreliable
458 * and in each dark corner broken firewalls sit, sending random
459 * errors ordered by their masters even this two messages finally lose
460 * their original sense (even Linux sends invalid PORT_UNREACHs)
461 *
462 * Now we are in compliance with RFCs.
463 * --ANK (980905)
464 */
465
466 inet = inet_sk(sk);
467 if (!sock_owned_by_user(sk) && inet->recverr) {
468 sk->sk_err = err;
469 sk->sk_error_report(sk);
470 } else { /* Only an error on timeout */
471 sk->sk_err_soft = err;
472 }
473
474 out:
475 bh_unlock_sock(sk);
476 sock_put(sk);
477 }
478
479 /* This routine computes an IPv4 TCP checksum. */
480 void tcp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb)
481 {
482 struct inet_sock *inet = inet_sk(sk);
483 struct tcphdr *th = tcp_hdr(skb);
484
485 if (skb->ip_summed == CHECKSUM_PARTIAL) {
486 th->check = ~tcp_v4_check(len, inet->saddr,
487 inet->daddr, 0);
488 skb->csum_start = skb_transport_header(skb) - skb->head;
489 skb->csum_offset = offsetof(struct tcphdr, check);
490 } else {
491 th->check = tcp_v4_check(len, inet->saddr, inet->daddr,
492 csum_partial(th,
493 th->doff << 2,
494 skb->csum));
495 }
496 }
497
498 int tcp_v4_gso_send_check(struct sk_buff *skb)
499 {
500 const struct iphdr *iph;
501 struct tcphdr *th;
502
503 if (!pskb_may_pull(skb, sizeof(*th)))
504 return -EINVAL;
505
506 iph = ip_hdr(skb);
507 th = tcp_hdr(skb);
508
509 th->check = 0;
510 th->check = ~tcp_v4_check(skb->len, iph->saddr, iph->daddr, 0);
511 skb->csum_start = skb_transport_header(skb) - skb->head;
512 skb->csum_offset = offsetof(struct tcphdr, check);
513 skb->ip_summed = CHECKSUM_PARTIAL;
514 return 0;
515 }
516
517 /*
518 * This routine will send an RST to the other tcp.
519 *
520 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
521 * for reset.
522 * Answer: if a packet caused RST, it is not for a socket
523 * existing in our system, if it is matched to a socket,
524 * it is just duplicate segment or bug in other side's TCP.
525 * So that we build reply only basing on parameters
526 * arrived with segment.
527 * Exception: precedence violation. We do not implement it in any case.
528 */
529
530 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
531 {
532 struct tcphdr *th = tcp_hdr(skb);
533 struct {
534 struct tcphdr th;
535 #ifdef CONFIG_TCP_MD5SIG
536 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
537 #endif
538 } rep;
539 struct ip_reply_arg arg;
540 #ifdef CONFIG_TCP_MD5SIG
541 struct tcp_md5sig_key *key;
542 #endif
543 struct net *net;
544
545 /* Never send a reset in response to a reset. */
546 if (th->rst)
547 return;
548
549 if (skb_rtable(skb)->rt_type != RTN_LOCAL)
550 return;
551
552 /* Swap the send and the receive. */
553 memset(&rep, 0, sizeof(rep));
554 rep.th.dest = th->source;
555 rep.th.source = th->dest;
556 rep.th.doff = sizeof(struct tcphdr) / 4;
557 rep.th.rst = 1;
558
559 if (th->ack) {
560 rep.th.seq = th->ack_seq;
561 } else {
562 rep.th.ack = 1;
563 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
564 skb->len - (th->doff << 2));
565 }
566
567 memset(&arg, 0, sizeof(arg));
568 arg.iov[0].iov_base = (unsigned char *)&rep;
569 arg.iov[0].iov_len = sizeof(rep.th);
570
571 #ifdef CONFIG_TCP_MD5SIG
572 key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
573 if (key) {
574 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
575 (TCPOPT_NOP << 16) |
576 (TCPOPT_MD5SIG << 8) |
577 TCPOLEN_MD5SIG);
578 /* Update length and the length the header thinks exists */
579 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
580 rep.th.doff = arg.iov[0].iov_len / 4;
581
582 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
583 key, ip_hdr(skb)->saddr,
584 ip_hdr(skb)->daddr, &rep.th);
585 }
586 #endif
587 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
588 ip_hdr(skb)->saddr, /* XXX */
589 arg.iov[0].iov_len, IPPROTO_TCP, 0);
590 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
591 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
592
593 net = dev_net(skb_dst(skb)->dev);
594 ip_send_reply(net->ipv4.tcp_sock, skb,
595 &arg, arg.iov[0].iov_len);
596
597 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
598 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
599 }
600
601 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
602 outside socket context is ugly, certainly. What can I do?
603 */
604
605 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
606 u32 win, u32 ts, int oif,
607 struct tcp_md5sig_key *key,
608 int reply_flags)
609 {
610 struct tcphdr *th = tcp_hdr(skb);
611 struct {
612 struct tcphdr th;
613 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
614 #ifdef CONFIG_TCP_MD5SIG
615 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
616 #endif
617 ];
618 } rep;
619 struct ip_reply_arg arg;
620 struct net *net = dev_net(skb_dst(skb)->dev);
621
622 memset(&rep.th, 0, sizeof(struct tcphdr));
623 memset(&arg, 0, sizeof(arg));
624
625 arg.iov[0].iov_base = (unsigned char *)&rep;
626 arg.iov[0].iov_len = sizeof(rep.th);
627 if (ts) {
628 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
629 (TCPOPT_TIMESTAMP << 8) |
630 TCPOLEN_TIMESTAMP);
631 rep.opt[1] = htonl(tcp_time_stamp);
632 rep.opt[2] = htonl(ts);
633 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
634 }
635
636 /* Swap the send and the receive. */
637 rep.th.dest = th->source;
638 rep.th.source = th->dest;
639 rep.th.doff = arg.iov[0].iov_len / 4;
640 rep.th.seq = htonl(seq);
641 rep.th.ack_seq = htonl(ack);
642 rep.th.ack = 1;
643 rep.th.window = htons(win);
644
645 #ifdef CONFIG_TCP_MD5SIG
646 if (key) {
647 int offset = (ts) ? 3 : 0;
648
649 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
650 (TCPOPT_NOP << 16) |
651 (TCPOPT_MD5SIG << 8) |
652 TCPOLEN_MD5SIG);
653 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
654 rep.th.doff = arg.iov[0].iov_len/4;
655
656 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
657 key, ip_hdr(skb)->saddr,
658 ip_hdr(skb)->daddr, &rep.th);
659 }
660 #endif
661 arg.flags = reply_flags;
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 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0
686 );
687
688 inet_twsk_put(tw);
689 }
690
691 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
692 struct request_sock *req)
693 {
694 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
695 tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
696 req->ts_recent,
697 0,
698 tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr),
699 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0);
700 }
701
702 /*
703 * Send a SYN-ACK after having received a SYN.
704 * This still operates on a request_sock only, not on a big
705 * socket.
706 */
707 static int __tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
708 struct dst_entry *dst)
709 {
710 const struct inet_request_sock *ireq = inet_rsk(req);
711 int err = -1;
712 struct sk_buff * skb;
713
714 /* First, grab a route. */
715 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
716 return -1;
717
718 skb = tcp_make_synack(sk, dst, req);
719
720 if (skb) {
721 struct tcphdr *th = tcp_hdr(skb);
722
723 th->check = tcp_v4_check(skb->len,
724 ireq->loc_addr,
725 ireq->rmt_addr,
726 csum_partial(th, skb->len,
727 skb->csum));
728
729 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
730 ireq->rmt_addr,
731 ireq->opt);
732 err = net_xmit_eval(err);
733 }
734
735 dst_release(dst);
736 return err;
737 }
738
739 static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req)
740 {
741 return __tcp_v4_send_synack(sk, req, NULL);
742 }
743
744 /*
745 * IPv4 request_sock destructor.
746 */
747 static void tcp_v4_reqsk_destructor(struct request_sock *req)
748 {
749 kfree(inet_rsk(req)->opt);
750 }
751
752 #ifdef CONFIG_SYN_COOKIES
753 static void syn_flood_warning(struct sk_buff *skb)
754 {
755 static unsigned long warntime;
756
757 if (time_after(jiffies, (warntime + HZ * 60))) {
758 warntime = jiffies;
759 printk(KERN_INFO
760 "possible SYN flooding on port %d. Sending cookies.\n",
761 ntohs(tcp_hdr(skb)->dest));
762 }
763 }
764 #endif
765
766 /*
767 * Save and compile IPv4 options into the request_sock if needed.
768 */
769 static struct ip_options *tcp_v4_save_options(struct sock *sk,
770 struct sk_buff *skb)
771 {
772 struct ip_options *opt = &(IPCB(skb)->opt);
773 struct ip_options *dopt = NULL;
774
775 if (opt && opt->optlen) {
776 int opt_size = optlength(opt);
777 dopt = kmalloc(opt_size, GFP_ATOMIC);
778 if (dopt) {
779 if (ip_options_echo(dopt, skb)) {
780 kfree(dopt);
781 dopt = NULL;
782 }
783 }
784 }
785 return dopt;
786 }
787
788 #ifdef CONFIG_TCP_MD5SIG
789 /*
790 * RFC2385 MD5 checksumming requires a mapping of
791 * IP address->MD5 Key.
792 * We need to maintain these in the sk structure.
793 */
794
795 /* Find the Key structure for an address. */
796 static struct tcp_md5sig_key *
797 tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
798 {
799 struct tcp_sock *tp = tcp_sk(sk);
800 int i;
801
802 if (!tp->md5sig_info || !tp->md5sig_info->entries4)
803 return NULL;
804 for (i = 0; i < tp->md5sig_info->entries4; i++) {
805 if (tp->md5sig_info->keys4[i].addr == addr)
806 return &tp->md5sig_info->keys4[i].base;
807 }
808 return NULL;
809 }
810
811 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
812 struct sock *addr_sk)
813 {
814 return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->daddr);
815 }
816
817 EXPORT_SYMBOL(tcp_v4_md5_lookup);
818
819 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
820 struct request_sock *req)
821 {
822 return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
823 }
824
825 /* This can be called on a newly created socket, from other files */
826 int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
827 u8 *newkey, u8 newkeylen)
828 {
829 /* Add Key to the list */
830 struct tcp_md5sig_key *key;
831 struct tcp_sock *tp = tcp_sk(sk);
832 struct tcp4_md5sig_key *keys;
833
834 key = tcp_v4_md5_do_lookup(sk, addr);
835 if (key) {
836 /* Pre-existing entry - just update that one. */
837 kfree(key->key);
838 key->key = newkey;
839 key->keylen = newkeylen;
840 } else {
841 struct tcp_md5sig_info *md5sig;
842
843 if (!tp->md5sig_info) {
844 tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
845 GFP_ATOMIC);
846 if (!tp->md5sig_info) {
847 kfree(newkey);
848 return -ENOMEM;
849 }
850 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
851 }
852 if (tcp_alloc_md5sig_pool() == NULL) {
853 kfree(newkey);
854 return -ENOMEM;
855 }
856 md5sig = tp->md5sig_info;
857
858 if (md5sig->alloced4 == md5sig->entries4) {
859 keys = kmalloc((sizeof(*keys) *
860 (md5sig->entries4 + 1)), GFP_ATOMIC);
861 if (!keys) {
862 kfree(newkey);
863 tcp_free_md5sig_pool();
864 return -ENOMEM;
865 }
866
867 if (md5sig->entries4)
868 memcpy(keys, md5sig->keys4,
869 sizeof(*keys) * md5sig->entries4);
870
871 /* Free old key list, and reference new one */
872 kfree(md5sig->keys4);
873 md5sig->keys4 = keys;
874 md5sig->alloced4++;
875 }
876 md5sig->entries4++;
877 md5sig->keys4[md5sig->entries4 - 1].addr = addr;
878 md5sig->keys4[md5sig->entries4 - 1].base.key = newkey;
879 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
880 }
881 return 0;
882 }
883
884 EXPORT_SYMBOL(tcp_v4_md5_do_add);
885
886 static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
887 u8 *newkey, u8 newkeylen)
888 {
889 return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->daddr,
890 newkey, newkeylen);
891 }
892
893 int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
894 {
895 struct tcp_sock *tp = tcp_sk(sk);
896 int i;
897
898 for (i = 0; i < tp->md5sig_info->entries4; i++) {
899 if (tp->md5sig_info->keys4[i].addr == addr) {
900 /* Free the key */
901 kfree(tp->md5sig_info->keys4[i].base.key);
902 tp->md5sig_info->entries4--;
903
904 if (tp->md5sig_info->entries4 == 0) {
905 kfree(tp->md5sig_info->keys4);
906 tp->md5sig_info->keys4 = NULL;
907 tp->md5sig_info->alloced4 = 0;
908 } else if (tp->md5sig_info->entries4 != i) {
909 /* Need to do some manipulation */
910 memmove(&tp->md5sig_info->keys4[i],
911 &tp->md5sig_info->keys4[i+1],
912 (tp->md5sig_info->entries4 - i) *
913 sizeof(struct tcp4_md5sig_key));
914 }
915 tcp_free_md5sig_pool();
916 return 0;
917 }
918 }
919 return -ENOENT;
920 }
921
922 EXPORT_SYMBOL(tcp_v4_md5_do_del);
923
924 static void tcp_v4_clear_md5_list(struct sock *sk)
925 {
926 struct tcp_sock *tp = tcp_sk(sk);
927
928 /* Free each key, then the set of key keys,
929 * the crypto element, and then decrement our
930 * hold on the last resort crypto.
931 */
932 if (tp->md5sig_info->entries4) {
933 int i;
934 for (i = 0; i < tp->md5sig_info->entries4; i++)
935 kfree(tp->md5sig_info->keys4[i].base.key);
936 tp->md5sig_info->entries4 = 0;
937 tcp_free_md5sig_pool();
938 }
939 if (tp->md5sig_info->keys4) {
940 kfree(tp->md5sig_info->keys4);
941 tp->md5sig_info->keys4 = NULL;
942 tp->md5sig_info->alloced4 = 0;
943 }
944 }
945
946 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
947 int optlen)
948 {
949 struct tcp_md5sig cmd;
950 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
951 u8 *newkey;
952
953 if (optlen < sizeof(cmd))
954 return -EINVAL;
955
956 if (copy_from_user(&cmd, optval, sizeof(cmd)))
957 return -EFAULT;
958
959 if (sin->sin_family != AF_INET)
960 return -EINVAL;
961
962 if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
963 if (!tcp_sk(sk)->md5sig_info)
964 return -ENOENT;
965 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
966 }
967
968 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
969 return -EINVAL;
970
971 if (!tcp_sk(sk)->md5sig_info) {
972 struct tcp_sock *tp = tcp_sk(sk);
973 struct tcp_md5sig_info *p = kzalloc(sizeof(*p), GFP_KERNEL);
974
975 if (!p)
976 return -EINVAL;
977
978 tp->md5sig_info = p;
979 sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
980 }
981
982 newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
983 if (!newkey)
984 return -ENOMEM;
985 return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
986 newkey, cmd.tcpm_keylen);
987 }
988
989 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
990 __be32 daddr, __be32 saddr, int nbytes)
991 {
992 struct tcp4_pseudohdr *bp;
993 struct scatterlist sg;
994
995 bp = &hp->md5_blk.ip4;
996
997 /*
998 * 1. the TCP pseudo-header (in the order: source IP address,
999 * destination IP address, zero-padded protocol number, and
1000 * segment length)
1001 */
1002 bp->saddr = saddr;
1003 bp->daddr = daddr;
1004 bp->pad = 0;
1005 bp->protocol = IPPROTO_TCP;
1006 bp->len = cpu_to_be16(nbytes);
1007
1008 sg_init_one(&sg, bp, sizeof(*bp));
1009 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1010 }
1011
1012 static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
1013 __be32 daddr, __be32 saddr, struct tcphdr *th)
1014 {
1015 struct tcp_md5sig_pool *hp;
1016 struct hash_desc *desc;
1017
1018 hp = tcp_get_md5sig_pool();
1019 if (!hp)
1020 goto clear_hash_noput;
1021 desc = &hp->md5_desc;
1022
1023 if (crypto_hash_init(desc))
1024 goto clear_hash;
1025 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1026 goto clear_hash;
1027 if (tcp_md5_hash_header(hp, th))
1028 goto clear_hash;
1029 if (tcp_md5_hash_key(hp, key))
1030 goto clear_hash;
1031 if (crypto_hash_final(desc, md5_hash))
1032 goto clear_hash;
1033
1034 tcp_put_md5sig_pool();
1035 return 0;
1036
1037 clear_hash:
1038 tcp_put_md5sig_pool();
1039 clear_hash_noput:
1040 memset(md5_hash, 0, 16);
1041 return 1;
1042 }
1043
1044 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1045 struct sock *sk, struct request_sock *req,
1046 struct sk_buff *skb)
1047 {
1048 struct tcp_md5sig_pool *hp;
1049 struct hash_desc *desc;
1050 struct tcphdr *th = tcp_hdr(skb);
1051 __be32 saddr, daddr;
1052
1053 if (sk) {
1054 saddr = inet_sk(sk)->saddr;
1055 daddr = inet_sk(sk)->daddr;
1056 } else if (req) {
1057 saddr = inet_rsk(req)->loc_addr;
1058 daddr = inet_rsk(req)->rmt_addr;
1059 } else {
1060 const struct iphdr *iph = ip_hdr(skb);
1061 saddr = iph->saddr;
1062 daddr = iph->daddr;
1063 }
1064
1065 hp = tcp_get_md5sig_pool();
1066 if (!hp)
1067 goto clear_hash_noput;
1068 desc = &hp->md5_desc;
1069
1070 if (crypto_hash_init(desc))
1071 goto clear_hash;
1072
1073 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1074 goto clear_hash;
1075 if (tcp_md5_hash_header(hp, th))
1076 goto clear_hash;
1077 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1078 goto clear_hash;
1079 if (tcp_md5_hash_key(hp, key))
1080 goto clear_hash;
1081 if (crypto_hash_final(desc, md5_hash))
1082 goto clear_hash;
1083
1084 tcp_put_md5sig_pool();
1085 return 0;
1086
1087 clear_hash:
1088 tcp_put_md5sig_pool();
1089 clear_hash_noput:
1090 memset(md5_hash, 0, 16);
1091 return 1;
1092 }
1093
1094 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1095
1096 static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1097 {
1098 /*
1099 * This gets called for each TCP segment that arrives
1100 * so we want to be efficient.
1101 * We have 3 drop cases:
1102 * o No MD5 hash and one expected.
1103 * o MD5 hash and we're not expecting one.
1104 * o MD5 hash and its wrong.
1105 */
1106 __u8 *hash_location = NULL;
1107 struct tcp_md5sig_key *hash_expected;
1108 const struct iphdr *iph = ip_hdr(skb);
1109 struct tcphdr *th = tcp_hdr(skb);
1110 int genhash;
1111 unsigned char newhash[16];
1112
1113 hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1114 hash_location = tcp_parse_md5sig_option(th);
1115
1116 /* We've parsed the options - do we have a hash? */
1117 if (!hash_expected && !hash_location)
1118 return 0;
1119
1120 if (hash_expected && !hash_location) {
1121 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1122 return 1;
1123 }
1124
1125 if (!hash_expected && hash_location) {
1126 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1127 return 1;
1128 }
1129
1130 /* Okay, so this is hash_expected and hash_location -
1131 * so we need to calculate the checksum.
1132 */
1133 genhash = tcp_v4_md5_hash_skb(newhash,
1134 hash_expected,
1135 NULL, NULL, skb);
1136
1137 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1138 if (net_ratelimit()) {
1139 printk(KERN_INFO "MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1140 &iph->saddr, ntohs(th->source),
1141 &iph->daddr, ntohs(th->dest),
1142 genhash ? " tcp_v4_calc_md5_hash failed" : "");
1143 }
1144 return 1;
1145 }
1146 return 0;
1147 }
1148
1149 #endif
1150
1151 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1152 .family = PF_INET,
1153 .obj_size = sizeof(struct tcp_request_sock),
1154 .rtx_syn_ack = tcp_v4_send_synack,
1155 .send_ack = tcp_v4_reqsk_send_ack,
1156 .destructor = tcp_v4_reqsk_destructor,
1157 .send_reset = tcp_v4_send_reset,
1158 };
1159
1160 #ifdef CONFIG_TCP_MD5SIG
1161 static struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1162 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1163 .calc_md5_hash = tcp_v4_md5_hash_skb,
1164 };
1165 #endif
1166
1167 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1168 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1169 .twsk_unique = tcp_twsk_unique,
1170 .twsk_destructor= tcp_twsk_destructor,
1171 };
1172
1173 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1174 {
1175 struct inet_request_sock *ireq;
1176 struct tcp_options_received tmp_opt;
1177 struct request_sock *req;
1178 __be32 saddr = ip_hdr(skb)->saddr;
1179 __be32 daddr = ip_hdr(skb)->daddr;
1180 __u32 isn = TCP_SKB_CB(skb)->when;
1181 struct dst_entry *dst = NULL;
1182 #ifdef CONFIG_SYN_COOKIES
1183 int want_cookie = 0;
1184 #else
1185 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
1186 #endif
1187
1188 /* Never answer to SYNs send to broadcast or multicast */
1189 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1190 goto drop;
1191
1192 /* TW buckets are converted to open requests without
1193 * limitations, they conserve resources and peer is
1194 * evidently real one.
1195 */
1196 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1197 #ifdef CONFIG_SYN_COOKIES
1198 if (sysctl_tcp_syncookies) {
1199 want_cookie = 1;
1200 } else
1201 #endif
1202 goto drop;
1203 }
1204
1205 /* Accept backlog is full. If we have already queued enough
1206 * of warm entries in syn queue, drop request. It is better than
1207 * clogging syn queue with openreqs with exponentially increasing
1208 * timeout.
1209 */
1210 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1211 goto drop;
1212
1213 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1214 if (!req)
1215 goto drop;
1216
1217 #ifdef CONFIG_TCP_MD5SIG
1218 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1219 #endif
1220
1221 tcp_clear_options(&tmp_opt);
1222 tmp_opt.mss_clamp = 536;
1223 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
1224
1225 tcp_parse_options(skb, &tmp_opt, 0);
1226
1227 if (want_cookie && !tmp_opt.saw_tstamp)
1228 tcp_clear_options(&tmp_opt);
1229
1230 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1231
1232 tcp_openreq_init(req, &tmp_opt, skb);
1233
1234 ireq = inet_rsk(req);
1235 ireq->loc_addr = daddr;
1236 ireq->rmt_addr = saddr;
1237 ireq->no_srccheck = inet_sk(sk)->transparent;
1238 ireq->opt = tcp_v4_save_options(sk, skb);
1239
1240 if (security_inet_conn_request(sk, skb, req))
1241 goto drop_and_free;
1242
1243 if (!want_cookie)
1244 TCP_ECN_create_request(req, tcp_hdr(skb));
1245
1246 if (want_cookie) {
1247 #ifdef CONFIG_SYN_COOKIES
1248 syn_flood_warning(skb);
1249 req->cookie_ts = tmp_opt.tstamp_ok;
1250 #endif
1251 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1252 } else if (!isn) {
1253 struct inet_peer *peer = NULL;
1254
1255 /* VJ's idea. We save last timestamp seen
1256 * from the destination in peer table, when entering
1257 * state TIME-WAIT, and check against it before
1258 * accepting new connection request.
1259 *
1260 * If "isn" is not zero, this request hit alive
1261 * timewait bucket, so that all the necessary checks
1262 * are made in the function processing timewait state.
1263 */
1264 if (tmp_opt.saw_tstamp &&
1265 tcp_death_row.sysctl_tw_recycle &&
1266 (dst = inet_csk_route_req(sk, req)) != NULL &&
1267 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1268 peer->v4daddr == saddr) {
1269 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1270 (s32)(peer->tcp_ts - req->ts_recent) >
1271 TCP_PAWS_WINDOW) {
1272 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1273 goto drop_and_release;
1274 }
1275 }
1276 /* Kill the following clause, if you dislike this way. */
1277 else if (!sysctl_tcp_syncookies &&
1278 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1279 (sysctl_max_syn_backlog >> 2)) &&
1280 (!peer || !peer->tcp_ts_stamp) &&
1281 (!dst || !dst_metric(dst, RTAX_RTT))) {
1282 /* Without syncookies last quarter of
1283 * backlog is filled with destinations,
1284 * proven to be alive.
1285 * It means that we continue to communicate
1286 * to destinations, already remembered
1287 * to the moment of synflood.
1288 */
1289 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
1290 &saddr, ntohs(tcp_hdr(skb)->source));
1291 goto drop_and_release;
1292 }
1293
1294 isn = tcp_v4_init_sequence(skb);
1295 }
1296 tcp_rsk(req)->snt_isn = isn;
1297
1298 if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
1299 goto drop_and_free;
1300
1301 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1302 return 0;
1303
1304 drop_and_release:
1305 dst_release(dst);
1306 drop_and_free:
1307 reqsk_free(req);
1308 drop:
1309 return 0;
1310 }
1311
1312
1313 /*
1314 * The three way handshake has completed - we got a valid synack -
1315 * now create the new socket.
1316 */
1317 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1318 struct request_sock *req,
1319 struct dst_entry *dst)
1320 {
1321 struct inet_request_sock *ireq;
1322 struct inet_sock *newinet;
1323 struct tcp_sock *newtp;
1324 struct sock *newsk;
1325 #ifdef CONFIG_TCP_MD5SIG
1326 struct tcp_md5sig_key *key;
1327 #endif
1328
1329 if (sk_acceptq_is_full(sk))
1330 goto exit_overflow;
1331
1332 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1333 goto exit;
1334
1335 newsk = tcp_create_openreq_child(sk, req, skb);
1336 if (!newsk)
1337 goto exit;
1338
1339 newsk->sk_gso_type = SKB_GSO_TCPV4;
1340 sk_setup_caps(newsk, dst);
1341
1342 newtp = tcp_sk(newsk);
1343 newinet = inet_sk(newsk);
1344 ireq = inet_rsk(req);
1345 newinet->daddr = ireq->rmt_addr;
1346 newinet->rcv_saddr = ireq->loc_addr;
1347 newinet->saddr = ireq->loc_addr;
1348 newinet->opt = ireq->opt;
1349 ireq->opt = NULL;
1350 newinet->mc_index = inet_iif(skb);
1351 newinet->mc_ttl = ip_hdr(skb)->ttl;
1352 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1353 if (newinet->opt)
1354 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1355 newinet->id = newtp->write_seq ^ jiffies;
1356
1357 tcp_mtup_init(newsk);
1358 tcp_sync_mss(newsk, dst_mtu(dst));
1359 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1360 if (tcp_sk(sk)->rx_opt.user_mss &&
1361 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1362 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1363
1364 tcp_initialize_rcv_mss(newsk);
1365
1366 #ifdef CONFIG_TCP_MD5SIG
1367 /* Copy over the MD5 key from the original socket */
1368 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
1369 /*
1370 * We're using one, so create a matching key
1371 * on the newsk structure. If we fail to get
1372 * memory, then we end up not copying the key
1373 * across. Shucks.
1374 */
1375 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1376 if (newkey != NULL)
1377 tcp_v4_md5_do_add(newsk, newinet->daddr,
1378 newkey, key->keylen);
1379 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1380 }
1381 #endif
1382
1383 __inet_hash_nolisten(newsk);
1384 __inet_inherit_port(sk, newsk);
1385
1386 return newsk;
1387
1388 exit_overflow:
1389 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1390 exit:
1391 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1392 dst_release(dst);
1393 return NULL;
1394 }
1395
1396 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1397 {
1398 struct tcphdr *th = tcp_hdr(skb);
1399 const struct iphdr *iph = ip_hdr(skb);
1400 struct sock *nsk;
1401 struct request_sock **prev;
1402 /* Find possible connection requests. */
1403 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1404 iph->saddr, iph->daddr);
1405 if (req)
1406 return tcp_check_req(sk, skb, req, prev);
1407
1408 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1409 th->source, iph->daddr, th->dest, inet_iif(skb));
1410
1411 if (nsk) {
1412 if (nsk->sk_state != TCP_TIME_WAIT) {
1413 bh_lock_sock(nsk);
1414 return nsk;
1415 }
1416 inet_twsk_put(inet_twsk(nsk));
1417 return NULL;
1418 }
1419
1420 #ifdef CONFIG_SYN_COOKIES
1421 if (!th->rst && !th->syn && th->ack)
1422 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1423 #endif
1424 return sk;
1425 }
1426
1427 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1428 {
1429 const struct iphdr *iph = ip_hdr(skb);
1430
1431 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1432 if (!tcp_v4_check(skb->len, iph->saddr,
1433 iph->daddr, skb->csum)) {
1434 skb->ip_summed = CHECKSUM_UNNECESSARY;
1435 return 0;
1436 }
1437 }
1438
1439 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1440 skb->len, IPPROTO_TCP, 0);
1441
1442 if (skb->len <= 76) {
1443 return __skb_checksum_complete(skb);
1444 }
1445 return 0;
1446 }
1447
1448
1449 /* The socket must have it's spinlock held when we get
1450 * here.
1451 *
1452 * We have a potential double-lock case here, so even when
1453 * doing backlog processing we use the BH locking scheme.
1454 * This is because we cannot sleep with the original spinlock
1455 * held.
1456 */
1457 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1458 {
1459 struct sock *rsk;
1460 #ifdef CONFIG_TCP_MD5SIG
1461 /*
1462 * We really want to reject the packet as early as possible
1463 * if:
1464 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1465 * o There is an MD5 option and we're not expecting one
1466 */
1467 if (tcp_v4_inbound_md5_hash(sk, skb))
1468 goto discard;
1469 #endif
1470
1471 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1472 TCP_CHECK_TIMER(sk);
1473 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1474 rsk = sk;
1475 goto reset;
1476 }
1477 TCP_CHECK_TIMER(sk);
1478 return 0;
1479 }
1480
1481 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1482 goto csum_err;
1483
1484 if (sk->sk_state == TCP_LISTEN) {
1485 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1486 if (!nsk)
1487 goto discard;
1488
1489 if (nsk != sk) {
1490 if (tcp_child_process(sk, nsk, skb)) {
1491 rsk = nsk;
1492 goto reset;
1493 }
1494 return 0;
1495 }
1496 }
1497
1498 TCP_CHECK_TIMER(sk);
1499 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1500 rsk = sk;
1501 goto reset;
1502 }
1503 TCP_CHECK_TIMER(sk);
1504 return 0;
1505
1506 reset:
1507 tcp_v4_send_reset(rsk, skb);
1508 discard:
1509 kfree_skb(skb);
1510 /* Be careful here. If this function gets more complicated and
1511 * gcc suffers from register pressure on the x86, sk (in %ebx)
1512 * might be destroyed here. This current version compiles correctly,
1513 * but you have been warned.
1514 */
1515 return 0;
1516
1517 csum_err:
1518 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1519 goto discard;
1520 }
1521
1522 /*
1523 * From tcp_input.c
1524 */
1525
1526 int tcp_v4_rcv(struct sk_buff *skb)
1527 {
1528 const struct iphdr *iph;
1529 struct tcphdr *th;
1530 struct sock *sk;
1531 int ret;
1532 struct net *net = dev_net(skb->dev);
1533
1534 if (skb->pkt_type != PACKET_HOST)
1535 goto discard_it;
1536
1537 /* Count it even if it's bad */
1538 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1539
1540 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1541 goto discard_it;
1542
1543 th = tcp_hdr(skb);
1544
1545 if (th->doff < sizeof(struct tcphdr) / 4)
1546 goto bad_packet;
1547 if (!pskb_may_pull(skb, th->doff * 4))
1548 goto discard_it;
1549
1550 /* An explanation is required here, I think.
1551 * Packet length and doff are validated by header prediction,
1552 * provided case of th->doff==0 is eliminated.
1553 * So, we defer the checks. */
1554 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1555 goto bad_packet;
1556
1557 th = tcp_hdr(skb);
1558 iph = ip_hdr(skb);
1559 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1560 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1561 skb->len - th->doff * 4);
1562 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1563 TCP_SKB_CB(skb)->when = 0;
1564 TCP_SKB_CB(skb)->flags = iph->tos;
1565 TCP_SKB_CB(skb)->sacked = 0;
1566
1567 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1568 if (!sk)
1569 goto no_tcp_socket;
1570
1571 process:
1572 if (sk->sk_state == TCP_TIME_WAIT)
1573 goto do_time_wait;
1574
1575 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1576 goto discard_and_relse;
1577 nf_reset(skb);
1578
1579 if (sk_filter(sk, skb))
1580 goto discard_and_relse;
1581
1582 skb->dev = NULL;
1583
1584 bh_lock_sock_nested(sk);
1585 ret = 0;
1586 if (!sock_owned_by_user(sk)) {
1587 #ifdef CONFIG_NET_DMA
1588 struct tcp_sock *tp = tcp_sk(sk);
1589 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1590 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1591 if (tp->ucopy.dma_chan)
1592 ret = tcp_v4_do_rcv(sk, skb);
1593 else
1594 #endif
1595 {
1596 if (!tcp_prequeue(sk, skb))
1597 ret = tcp_v4_do_rcv(sk, skb);
1598 }
1599 } else
1600 sk_add_backlog(sk, skb);
1601 bh_unlock_sock(sk);
1602
1603 sock_put(sk);
1604
1605 return ret;
1606
1607 no_tcp_socket:
1608 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1609 goto discard_it;
1610
1611 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1612 bad_packet:
1613 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1614 } else {
1615 tcp_v4_send_reset(NULL, skb);
1616 }
1617
1618 discard_it:
1619 /* Discard frame. */
1620 kfree_skb(skb);
1621 return 0;
1622
1623 discard_and_relse:
1624 sock_put(sk);
1625 goto discard_it;
1626
1627 do_time_wait:
1628 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1629 inet_twsk_put(inet_twsk(sk));
1630 goto discard_it;
1631 }
1632
1633 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1634 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1635 inet_twsk_put(inet_twsk(sk));
1636 goto discard_it;
1637 }
1638 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1639 case TCP_TW_SYN: {
1640 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1641 &tcp_hashinfo,
1642 iph->daddr, th->dest,
1643 inet_iif(skb));
1644 if (sk2) {
1645 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1646 inet_twsk_put(inet_twsk(sk));
1647 sk = sk2;
1648 goto process;
1649 }
1650 /* Fall through to ACK */
1651 }
1652 case TCP_TW_ACK:
1653 tcp_v4_timewait_ack(sk, skb);
1654 break;
1655 case TCP_TW_RST:
1656 goto no_tcp_socket;
1657 case TCP_TW_SUCCESS:;
1658 }
1659 goto discard_it;
1660 }
1661
1662 /* VJ's idea. Save last timestamp seen from this destination
1663 * and hold it at least for normal timewait interval to use for duplicate
1664 * segment detection in subsequent connections, before they enter synchronized
1665 * state.
1666 */
1667
1668 int tcp_v4_remember_stamp(struct sock *sk)
1669 {
1670 struct inet_sock *inet = inet_sk(sk);
1671 struct tcp_sock *tp = tcp_sk(sk);
1672 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1673 struct inet_peer *peer = NULL;
1674 int release_it = 0;
1675
1676 if (!rt || rt->rt_dst != inet->daddr) {
1677 peer = inet_getpeer(inet->daddr, 1);
1678 release_it = 1;
1679 } else {
1680 if (!rt->peer)
1681 rt_bind_peer(rt, 1);
1682 peer = rt->peer;
1683 }
1684
1685 if (peer) {
1686 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1687 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1688 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1689 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1690 peer->tcp_ts = tp->rx_opt.ts_recent;
1691 }
1692 if (release_it)
1693 inet_putpeer(peer);
1694 return 1;
1695 }
1696
1697 return 0;
1698 }
1699
1700 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1701 {
1702 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1703
1704 if (peer) {
1705 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1706
1707 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1708 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1709 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1710 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1711 peer->tcp_ts = tcptw->tw_ts_recent;
1712 }
1713 inet_putpeer(peer);
1714 return 1;
1715 }
1716
1717 return 0;
1718 }
1719
1720 struct inet_connection_sock_af_ops ipv4_specific = {
1721 .queue_xmit = ip_queue_xmit,
1722 .send_check = tcp_v4_send_check,
1723 .rebuild_header = inet_sk_rebuild_header,
1724 .conn_request = tcp_v4_conn_request,
1725 .syn_recv_sock = tcp_v4_syn_recv_sock,
1726 .remember_stamp = tcp_v4_remember_stamp,
1727 .net_header_len = sizeof(struct iphdr),
1728 .setsockopt = ip_setsockopt,
1729 .getsockopt = ip_getsockopt,
1730 .addr2sockaddr = inet_csk_addr2sockaddr,
1731 .sockaddr_len = sizeof(struct sockaddr_in),
1732 .bind_conflict = inet_csk_bind_conflict,
1733 #ifdef CONFIG_COMPAT
1734 .compat_setsockopt = compat_ip_setsockopt,
1735 .compat_getsockopt = compat_ip_getsockopt,
1736 #endif
1737 };
1738
1739 #ifdef CONFIG_TCP_MD5SIG
1740 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1741 .md5_lookup = tcp_v4_md5_lookup,
1742 .calc_md5_hash = tcp_v4_md5_hash_skb,
1743 .md5_add = tcp_v4_md5_add_func,
1744 .md5_parse = tcp_v4_parse_md5_keys,
1745 };
1746 #endif
1747
1748 /* NOTE: A lot of things set to zero explicitly by call to
1749 * sk_alloc() so need not be done here.
1750 */
1751 static int tcp_v4_init_sock(struct sock *sk)
1752 {
1753 struct inet_connection_sock *icsk = inet_csk(sk);
1754 struct tcp_sock *tp = tcp_sk(sk);
1755
1756 skb_queue_head_init(&tp->out_of_order_queue);
1757 tcp_init_xmit_timers(sk);
1758 tcp_prequeue_init(tp);
1759
1760 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1761 tp->mdev = TCP_TIMEOUT_INIT;
1762
1763 /* So many TCP implementations out there (incorrectly) count the
1764 * initial SYN frame in their delayed-ACK and congestion control
1765 * algorithms that we must have the following bandaid to talk
1766 * efficiently to them. -DaveM
1767 */
1768 tp->snd_cwnd = 2;
1769
1770 /* See draft-stevens-tcpca-spec-01 for discussion of the
1771 * initialization of these values.
1772 */
1773 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1774 tp->snd_cwnd_clamp = ~0;
1775 tp->mss_cache = 536;
1776
1777 tp->reordering = sysctl_tcp_reordering;
1778 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1779
1780 sk->sk_state = TCP_CLOSE;
1781
1782 sk->sk_write_space = sk_stream_write_space;
1783 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1784
1785 icsk->icsk_af_ops = &ipv4_specific;
1786 icsk->icsk_sync_mss = tcp_sync_mss;
1787 #ifdef CONFIG_TCP_MD5SIG
1788 tp->af_specific = &tcp_sock_ipv4_specific;
1789 #endif
1790
1791 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1792 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1793
1794 local_bh_disable();
1795 percpu_counter_inc(&tcp_sockets_allocated);
1796 local_bh_enable();
1797
1798 return 0;
1799 }
1800
1801 void tcp_v4_destroy_sock(struct sock *sk)
1802 {
1803 struct tcp_sock *tp = tcp_sk(sk);
1804
1805 tcp_clear_xmit_timers(sk);
1806
1807 tcp_cleanup_congestion_control(sk);
1808
1809 /* Cleanup up the write buffer. */
1810 tcp_write_queue_purge(sk);
1811
1812 /* Cleans up our, hopefully empty, out_of_order_queue. */
1813 __skb_queue_purge(&tp->out_of_order_queue);
1814
1815 #ifdef CONFIG_TCP_MD5SIG
1816 /* Clean up the MD5 key list, if any */
1817 if (tp->md5sig_info) {
1818 tcp_v4_clear_md5_list(sk);
1819 kfree(tp->md5sig_info);
1820 tp->md5sig_info = NULL;
1821 }
1822 #endif
1823
1824 #ifdef CONFIG_NET_DMA
1825 /* Cleans up our sk_async_wait_queue */
1826 __skb_queue_purge(&sk->sk_async_wait_queue);
1827 #endif
1828
1829 /* Clean prequeue, it must be empty really */
1830 __skb_queue_purge(&tp->ucopy.prequeue);
1831
1832 /* Clean up a referenced TCP bind bucket. */
1833 if (inet_csk(sk)->icsk_bind_hash)
1834 inet_put_port(sk);
1835
1836 /*
1837 * If sendmsg cached page exists, toss it.
1838 */
1839 if (sk->sk_sndmsg_page) {
1840 __free_page(sk->sk_sndmsg_page);
1841 sk->sk_sndmsg_page = NULL;
1842 }
1843
1844 percpu_counter_dec(&tcp_sockets_allocated);
1845 }
1846
1847 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1848
1849 #ifdef CONFIG_PROC_FS
1850 /* Proc filesystem TCP sock list dumping. */
1851
1852 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
1853 {
1854 return hlist_nulls_empty(head) ? NULL :
1855 list_entry(head->first, struct inet_timewait_sock, tw_node);
1856 }
1857
1858 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1859 {
1860 return !is_a_nulls(tw->tw_node.next) ?
1861 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1862 }
1863
1864 static void *listening_get_next(struct seq_file *seq, void *cur)
1865 {
1866 struct inet_connection_sock *icsk;
1867 struct hlist_nulls_node *node;
1868 struct sock *sk = cur;
1869 struct inet_listen_hashbucket *ilb;
1870 struct tcp_iter_state *st = seq->private;
1871 struct net *net = seq_file_net(seq);
1872
1873 if (!sk) {
1874 st->bucket = 0;
1875 ilb = &tcp_hashinfo.listening_hash[0];
1876 spin_lock_bh(&ilb->lock);
1877 sk = sk_nulls_head(&ilb->head);
1878 goto get_sk;
1879 }
1880 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1881 ++st->num;
1882
1883 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1884 struct request_sock *req = cur;
1885
1886 icsk = inet_csk(st->syn_wait_sk);
1887 req = req->dl_next;
1888 while (1) {
1889 while (req) {
1890 if (req->rsk_ops->family == st->family) {
1891 cur = req;
1892 goto out;
1893 }
1894 req = req->dl_next;
1895 }
1896 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1897 break;
1898 get_req:
1899 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1900 }
1901 sk = sk_next(st->syn_wait_sk);
1902 st->state = TCP_SEQ_STATE_LISTENING;
1903 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1904 } else {
1905 icsk = inet_csk(sk);
1906 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1907 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1908 goto start_req;
1909 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1910 sk = sk_next(sk);
1911 }
1912 get_sk:
1913 sk_nulls_for_each_from(sk, node) {
1914 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
1915 cur = sk;
1916 goto out;
1917 }
1918 icsk = inet_csk(sk);
1919 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1920 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1921 start_req:
1922 st->uid = sock_i_uid(sk);
1923 st->syn_wait_sk = sk;
1924 st->state = TCP_SEQ_STATE_OPENREQ;
1925 st->sbucket = 0;
1926 goto get_req;
1927 }
1928 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1929 }
1930 spin_unlock_bh(&ilb->lock);
1931 if (++st->bucket < INET_LHTABLE_SIZE) {
1932 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1933 spin_lock_bh(&ilb->lock);
1934 sk = sk_nulls_head(&ilb->head);
1935 goto get_sk;
1936 }
1937 cur = NULL;
1938 out:
1939 return cur;
1940 }
1941
1942 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1943 {
1944 void *rc = listening_get_next(seq, NULL);
1945
1946 while (rc && *pos) {
1947 rc = listening_get_next(seq, rc);
1948 --*pos;
1949 }
1950 return rc;
1951 }
1952
1953 static inline int empty_bucket(struct tcp_iter_state *st)
1954 {
1955 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
1956 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
1957 }
1958
1959 static void *established_get_first(struct seq_file *seq)
1960 {
1961 struct tcp_iter_state *st = seq->private;
1962 struct net *net = seq_file_net(seq);
1963 void *rc = NULL;
1964
1965 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1966 struct sock *sk;
1967 struct hlist_nulls_node *node;
1968 struct inet_timewait_sock *tw;
1969 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1970
1971 /* Lockless fast path for the common case of empty buckets */
1972 if (empty_bucket(st))
1973 continue;
1974
1975 spin_lock_bh(lock);
1976 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1977 if (sk->sk_family != st->family ||
1978 !net_eq(sock_net(sk), net)) {
1979 continue;
1980 }
1981 rc = sk;
1982 goto out;
1983 }
1984 st->state = TCP_SEQ_STATE_TIME_WAIT;
1985 inet_twsk_for_each(tw, node,
1986 &tcp_hashinfo.ehash[st->bucket].twchain) {
1987 if (tw->tw_family != st->family ||
1988 !net_eq(twsk_net(tw), net)) {
1989 continue;
1990 }
1991 rc = tw;
1992 goto out;
1993 }
1994 spin_unlock_bh(lock);
1995 st->state = TCP_SEQ_STATE_ESTABLISHED;
1996 }
1997 out:
1998 return rc;
1999 }
2000
2001 static void *established_get_next(struct seq_file *seq, void *cur)
2002 {
2003 struct sock *sk = cur;
2004 struct inet_timewait_sock *tw;
2005 struct hlist_nulls_node *node;
2006 struct tcp_iter_state *st = seq->private;
2007 struct net *net = seq_file_net(seq);
2008
2009 ++st->num;
2010
2011 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2012 tw = cur;
2013 tw = tw_next(tw);
2014 get_tw:
2015 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2016 tw = tw_next(tw);
2017 }
2018 if (tw) {
2019 cur = tw;
2020 goto out;
2021 }
2022 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2023 st->state = TCP_SEQ_STATE_ESTABLISHED;
2024
2025 /* Look for next non empty bucket */
2026 while (++st->bucket < tcp_hashinfo.ehash_size &&
2027 empty_bucket(st))
2028 ;
2029 if (st->bucket >= tcp_hashinfo.ehash_size)
2030 return NULL;
2031
2032 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2033 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2034 } else
2035 sk = sk_nulls_next(sk);
2036
2037 sk_nulls_for_each_from(sk, node) {
2038 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2039 goto found;
2040 }
2041
2042 st->state = TCP_SEQ_STATE_TIME_WAIT;
2043 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2044 goto get_tw;
2045 found:
2046 cur = sk;
2047 out:
2048 return cur;
2049 }
2050
2051 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2052 {
2053 void *rc = established_get_first(seq);
2054
2055 while (rc && pos) {
2056 rc = established_get_next(seq, rc);
2057 --pos;
2058 }
2059 return rc;
2060 }
2061
2062 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2063 {
2064 void *rc;
2065 struct tcp_iter_state *st = seq->private;
2066
2067 st->state = TCP_SEQ_STATE_LISTENING;
2068 rc = listening_get_idx(seq, &pos);
2069
2070 if (!rc) {
2071 st->state = TCP_SEQ_STATE_ESTABLISHED;
2072 rc = established_get_idx(seq, pos);
2073 }
2074
2075 return rc;
2076 }
2077
2078 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2079 {
2080 struct tcp_iter_state *st = seq->private;
2081 st->state = TCP_SEQ_STATE_LISTENING;
2082 st->num = 0;
2083 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2084 }
2085
2086 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2087 {
2088 void *rc = NULL;
2089 struct tcp_iter_state *st;
2090
2091 if (v == SEQ_START_TOKEN) {
2092 rc = tcp_get_idx(seq, 0);
2093 goto out;
2094 }
2095 st = seq->private;
2096
2097 switch (st->state) {
2098 case TCP_SEQ_STATE_OPENREQ:
2099 case TCP_SEQ_STATE_LISTENING:
2100 rc = listening_get_next(seq, v);
2101 if (!rc) {
2102 st->state = TCP_SEQ_STATE_ESTABLISHED;
2103 rc = established_get_first(seq);
2104 }
2105 break;
2106 case TCP_SEQ_STATE_ESTABLISHED:
2107 case TCP_SEQ_STATE_TIME_WAIT:
2108 rc = established_get_next(seq, v);
2109 break;
2110 }
2111 out:
2112 ++*pos;
2113 return rc;
2114 }
2115
2116 static void tcp_seq_stop(struct seq_file *seq, void *v)
2117 {
2118 struct tcp_iter_state *st = seq->private;
2119
2120 switch (st->state) {
2121 case TCP_SEQ_STATE_OPENREQ:
2122 if (v) {
2123 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2124 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2125 }
2126 case TCP_SEQ_STATE_LISTENING:
2127 if (v != SEQ_START_TOKEN)
2128 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2129 break;
2130 case TCP_SEQ_STATE_TIME_WAIT:
2131 case TCP_SEQ_STATE_ESTABLISHED:
2132 if (v)
2133 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2134 break;
2135 }
2136 }
2137
2138 static int tcp_seq_open(struct inode *inode, struct file *file)
2139 {
2140 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2141 struct tcp_iter_state *s;
2142 int err;
2143
2144 err = seq_open_net(inode, file, &afinfo->seq_ops,
2145 sizeof(struct tcp_iter_state));
2146 if (err < 0)
2147 return err;
2148
2149 s = ((struct seq_file *)file->private_data)->private;
2150 s->family = afinfo->family;
2151 return 0;
2152 }
2153
2154 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2155 {
2156 int rc = 0;
2157 struct proc_dir_entry *p;
2158
2159 afinfo->seq_fops.open = tcp_seq_open;
2160 afinfo->seq_fops.read = seq_read;
2161 afinfo->seq_fops.llseek = seq_lseek;
2162 afinfo->seq_fops.release = seq_release_net;
2163
2164 afinfo->seq_ops.start = tcp_seq_start;
2165 afinfo->seq_ops.next = tcp_seq_next;
2166 afinfo->seq_ops.stop = tcp_seq_stop;
2167
2168 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2169 &afinfo->seq_fops, afinfo);
2170 if (!p)
2171 rc = -ENOMEM;
2172 return rc;
2173 }
2174
2175 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2176 {
2177 proc_net_remove(net, afinfo->name);
2178 }
2179
2180 static void get_openreq4(struct sock *sk, struct request_sock *req,
2181 struct seq_file *f, int i, int uid, int *len)
2182 {
2183 const struct inet_request_sock *ireq = inet_rsk(req);
2184 int ttd = req->expires - jiffies;
2185
2186 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2187 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
2188 i,
2189 ireq->loc_addr,
2190 ntohs(inet_sk(sk)->sport),
2191 ireq->rmt_addr,
2192 ntohs(ireq->rmt_port),
2193 TCP_SYN_RECV,
2194 0, 0, /* could print option size, but that is af dependent. */
2195 1, /* timers active (only the expire timer) */
2196 jiffies_to_clock_t(ttd),
2197 req->retrans,
2198 uid,
2199 0, /* non standard timer */
2200 0, /* open_requests have no inode */
2201 atomic_read(&sk->sk_refcnt),
2202 req,
2203 len);
2204 }
2205
2206 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2207 {
2208 int timer_active;
2209 unsigned long timer_expires;
2210 struct tcp_sock *tp = tcp_sk(sk);
2211 const struct inet_connection_sock *icsk = inet_csk(sk);
2212 struct inet_sock *inet = inet_sk(sk);
2213 __be32 dest = inet->daddr;
2214 __be32 src = inet->rcv_saddr;
2215 __u16 destp = ntohs(inet->dport);
2216 __u16 srcp = ntohs(inet->sport);
2217
2218 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2219 timer_active = 1;
2220 timer_expires = icsk->icsk_timeout;
2221 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2222 timer_active = 4;
2223 timer_expires = icsk->icsk_timeout;
2224 } else if (timer_pending(&sk->sk_timer)) {
2225 timer_active = 2;
2226 timer_expires = sk->sk_timer.expires;
2227 } else {
2228 timer_active = 0;
2229 timer_expires = jiffies;
2230 }
2231
2232 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2233 "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2234 i, src, srcp, dest, destp, sk->sk_state,
2235 tp->write_seq - tp->snd_una,
2236 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2237 (tp->rcv_nxt - tp->copied_seq),
2238 timer_active,
2239 jiffies_to_clock_t(timer_expires - jiffies),
2240 icsk->icsk_retransmits,
2241 sock_i_uid(sk),
2242 icsk->icsk_probes_out,
2243 sock_i_ino(sk),
2244 atomic_read(&sk->sk_refcnt), sk,
2245 jiffies_to_clock_t(icsk->icsk_rto),
2246 jiffies_to_clock_t(icsk->icsk_ack.ato),
2247 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2248 tp->snd_cwnd,
2249 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh,
2250 len);
2251 }
2252
2253 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2254 struct seq_file *f, int i, int *len)
2255 {
2256 __be32 dest, src;
2257 __u16 destp, srcp;
2258 int ttd = tw->tw_ttd - jiffies;
2259
2260 if (ttd < 0)
2261 ttd = 0;
2262
2263 dest = tw->tw_daddr;
2264 src = tw->tw_rcv_saddr;
2265 destp = ntohs(tw->tw_dport);
2266 srcp = ntohs(tw->tw_sport);
2267
2268 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2269 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
2270 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2271 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2272 atomic_read(&tw->tw_refcnt), tw, len);
2273 }
2274
2275 #define TMPSZ 150
2276
2277 static int tcp4_seq_show(struct seq_file *seq, void *v)
2278 {
2279 struct tcp_iter_state *st;
2280 int len;
2281
2282 if (v == SEQ_START_TOKEN) {
2283 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2284 " sl local_address rem_address st tx_queue "
2285 "rx_queue tr tm->when retrnsmt uid timeout "
2286 "inode");
2287 goto out;
2288 }
2289 st = seq->private;
2290
2291 switch (st->state) {
2292 case TCP_SEQ_STATE_LISTENING:
2293 case TCP_SEQ_STATE_ESTABLISHED:
2294 get_tcp4_sock(v, seq, st->num, &len);
2295 break;
2296 case TCP_SEQ_STATE_OPENREQ:
2297 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2298 break;
2299 case TCP_SEQ_STATE_TIME_WAIT:
2300 get_timewait4_sock(v, seq, st->num, &len);
2301 break;
2302 }
2303 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2304 out:
2305 return 0;
2306 }
2307
2308 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2309 .name = "tcp",
2310 .family = AF_INET,
2311 .seq_fops = {
2312 .owner = THIS_MODULE,
2313 },
2314 .seq_ops = {
2315 .show = tcp4_seq_show,
2316 },
2317 };
2318
2319 static int tcp4_proc_init_net(struct net *net)
2320 {
2321 return tcp_proc_register(net, &tcp4_seq_afinfo);
2322 }
2323
2324 static void tcp4_proc_exit_net(struct net *net)
2325 {
2326 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2327 }
2328
2329 static struct pernet_operations tcp4_net_ops = {
2330 .init = tcp4_proc_init_net,
2331 .exit = tcp4_proc_exit_net,
2332 };
2333
2334 int __init tcp4_proc_init(void)
2335 {
2336 return register_pernet_subsys(&tcp4_net_ops);
2337 }
2338
2339 void tcp4_proc_exit(void)
2340 {
2341 unregister_pernet_subsys(&tcp4_net_ops);
2342 }
2343 #endif /* CONFIG_PROC_FS */
2344
2345 struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2346 {
2347 struct iphdr *iph = skb_gro_network_header(skb);
2348
2349 switch (skb->ip_summed) {
2350 case CHECKSUM_COMPLETE:
2351 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
2352 skb->csum)) {
2353 skb->ip_summed = CHECKSUM_UNNECESSARY;
2354 break;
2355 }
2356
2357 /* fall through */
2358 case CHECKSUM_NONE:
2359 NAPI_GRO_CB(skb)->flush = 1;
2360 return NULL;
2361 }
2362
2363 return tcp_gro_receive(head, skb);
2364 }
2365 EXPORT_SYMBOL(tcp4_gro_receive);
2366
2367 int tcp4_gro_complete(struct sk_buff *skb)
2368 {
2369 struct iphdr *iph = ip_hdr(skb);
2370 struct tcphdr *th = tcp_hdr(skb);
2371
2372 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
2373 iph->saddr, iph->daddr, 0);
2374 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
2375
2376 return tcp_gro_complete(skb);
2377 }
2378 EXPORT_SYMBOL(tcp4_gro_complete);
2379
2380 struct proto tcp_prot = {
2381 .name = "TCP",
2382 .owner = THIS_MODULE,
2383 .close = tcp_close,
2384 .connect = tcp_v4_connect,
2385 .disconnect = tcp_disconnect,
2386 .accept = inet_csk_accept,
2387 .ioctl = tcp_ioctl,
2388 .init = tcp_v4_init_sock,
2389 .destroy = tcp_v4_destroy_sock,
2390 .shutdown = tcp_shutdown,
2391 .setsockopt = tcp_setsockopt,
2392 .getsockopt = tcp_getsockopt,
2393 .recvmsg = tcp_recvmsg,
2394 .backlog_rcv = tcp_v4_do_rcv,
2395 .hash = inet_hash,
2396 .unhash = inet_unhash,
2397 .get_port = inet_csk_get_port,
2398 .enter_memory_pressure = tcp_enter_memory_pressure,
2399 .sockets_allocated = &tcp_sockets_allocated,
2400 .orphan_count = &tcp_orphan_count,
2401 .memory_allocated = &tcp_memory_allocated,
2402 .memory_pressure = &tcp_memory_pressure,
2403 .sysctl_mem = sysctl_tcp_mem,
2404 .sysctl_wmem = sysctl_tcp_wmem,
2405 .sysctl_rmem = sysctl_tcp_rmem,
2406 .max_header = MAX_TCP_HEADER,
2407 .obj_size = sizeof(struct tcp_sock),
2408 .slab_flags = SLAB_DESTROY_BY_RCU,
2409 .twsk_prot = &tcp_timewait_sock_ops,
2410 .rsk_prot = &tcp_request_sock_ops,
2411 .h.hashinfo = &tcp_hashinfo,
2412 #ifdef CONFIG_COMPAT
2413 .compat_setsockopt = compat_tcp_setsockopt,
2414 .compat_getsockopt = compat_tcp_getsockopt,
2415 #endif
2416 };
2417
2418
2419 static int __net_init tcp_sk_init(struct net *net)
2420 {
2421 return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2422 PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2423 }
2424
2425 static void __net_exit tcp_sk_exit(struct net *net)
2426 {
2427 inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2428 inet_twsk_purge(net, &tcp_hashinfo, &tcp_death_row, AF_INET);
2429 }
2430
2431 static struct pernet_operations __net_initdata tcp_sk_ops = {
2432 .init = tcp_sk_init,
2433 .exit = tcp_sk_exit,
2434 };
2435
2436 void __init tcp_v4_init(void)
2437 {
2438 inet_hashinfo_init(&tcp_hashinfo);
2439 if (register_pernet_subsys(&tcp_sk_ops))
2440 panic("Failed to create the TCP control socket.\n");
2441 }
2442
2443 EXPORT_SYMBOL(ipv4_specific);
2444 EXPORT_SYMBOL(tcp_hashinfo);
2445 EXPORT_SYMBOL(tcp_prot);
2446 EXPORT_SYMBOL(tcp_v4_conn_request);
2447 EXPORT_SYMBOL(tcp_v4_connect);
2448 EXPORT_SYMBOL(tcp_v4_do_rcv);
2449 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2450 EXPORT_SYMBOL(tcp_v4_send_check);
2451 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2452
2453 #ifdef CONFIG_PROC_FS
2454 EXPORT_SYMBOL(tcp_proc_register);
2455 EXPORT_SYMBOL(tcp_proc_unregister);
2456 #endif
2457 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2458
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