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x86, irq: Remove IRQ_DISABLED check in process context IRQ move
[linux-2.6/mini2440.git] / net / ipv4 / tcp_ipv4.c
blob5d427f86b4142115cbc6c02222b8bbd0b34f9506
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->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->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->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 };
1164 #endif
1165
1166 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1167 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1168 .twsk_unique = tcp_twsk_unique,
1169 .twsk_destructor= tcp_twsk_destructor,
1170 };
1171
1172 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1173 {
1174 struct inet_request_sock *ireq;
1175 struct tcp_options_received tmp_opt;
1176 struct request_sock *req;
1177 __be32 saddr = ip_hdr(skb)->saddr;
1178 __be32 daddr = ip_hdr(skb)->daddr;
1179 __u32 isn = TCP_SKB_CB(skb)->when;
1180 struct dst_entry *dst = NULL;
1181 #ifdef CONFIG_SYN_COOKIES
1182 int want_cookie = 0;
1183 #else
1184 #define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
1185 #endif
1186
1187 /* Never answer to SYNs send to broadcast or multicast */
1188 if (skb->rtable->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1189 goto drop;
1190
1191 /* TW buckets are converted to open requests without
1192 * limitations, they conserve resources and peer is
1193 * evidently real one.
1194 */
1195 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1196 #ifdef CONFIG_SYN_COOKIES
1197 if (sysctl_tcp_syncookies) {
1198 want_cookie = 1;
1199 } else
1200 #endif
1201 goto drop;
1202 }
1203
1204 /* Accept backlog is full. If we have already queued enough
1205 * of warm entries in syn queue, drop request. It is better than
1206 * clogging syn queue with openreqs with exponentially increasing
1207 * timeout.
1208 */
1209 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1210 goto drop;
1211
1212 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1213 if (!req)
1214 goto drop;
1215
1216 #ifdef CONFIG_TCP_MD5SIG
1217 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1218 #endif
1219
1220 tcp_clear_options(&tmp_opt);
1221 tmp_opt.mss_clamp = 536;
1222 tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
1223
1224 tcp_parse_options(skb, &tmp_opt, 0);
1225
1226 if (want_cookie && !tmp_opt.saw_tstamp)
1227 tcp_clear_options(&tmp_opt);
1228
1229 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1230
1231 tcp_openreq_init(req, &tmp_opt, skb);
1232
1233 ireq = inet_rsk(req);
1234 ireq->loc_addr = daddr;
1235 ireq->rmt_addr = saddr;
1236 ireq->no_srccheck = inet_sk(sk)->transparent;
1237 ireq->opt = tcp_v4_save_options(sk, skb);
1238
1239 if (security_inet_conn_request(sk, skb, req))
1240 goto drop_and_free;
1241
1242 if (!want_cookie)
1243 TCP_ECN_create_request(req, tcp_hdr(skb));
1244
1245 if (want_cookie) {
1246 #ifdef CONFIG_SYN_COOKIES
1247 syn_flood_warning(skb);
1248 req->cookie_ts = tmp_opt.tstamp_ok;
1249 #endif
1250 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1251 } else if (!isn) {
1252 struct inet_peer *peer = NULL;
1253
1254 /* VJ's idea. We save last timestamp seen
1255 * from the destination in peer table, when entering
1256 * state TIME-WAIT, and check against it before
1257 * accepting new connection request.
1258 *
1259 * If "isn" is not zero, this request hit alive
1260 * timewait bucket, so that all the necessary checks
1261 * are made in the function processing timewait state.
1262 */
1263 if (tmp_opt.saw_tstamp &&
1264 tcp_death_row.sysctl_tw_recycle &&
1265 (dst = inet_csk_route_req(sk, req)) != NULL &&
1266 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1267 peer->v4daddr == saddr) {
1268 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1269 (s32)(peer->tcp_ts - req->ts_recent) >
1270 TCP_PAWS_WINDOW) {
1271 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1272 goto drop_and_release;
1273 }
1274 }
1275 /* Kill the following clause, if you dislike this way. */
1276 else if (!sysctl_tcp_syncookies &&
1277 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1278 (sysctl_max_syn_backlog >> 2)) &&
1279 (!peer || !peer->tcp_ts_stamp) &&
1280 (!dst || !dst_metric(dst, RTAX_RTT))) {
1281 /* Without syncookies last quarter of
1282 * backlog is filled with destinations,
1283 * proven to be alive.
1284 * It means that we continue to communicate
1285 * to destinations, already remembered
1286 * to the moment of synflood.
1287 */
1288 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
1289 &saddr, ntohs(tcp_hdr(skb)->source));
1290 goto drop_and_release;
1291 }
1292
1293 isn = tcp_v4_init_sequence(skb);
1294 }
1295 tcp_rsk(req)->snt_isn = isn;
1296
1297 if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
1298 goto drop_and_free;
1299
1300 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1301 return 0;
1302
1303 drop_and_release:
1304 dst_release(dst);
1305 drop_and_free:
1306 reqsk_free(req);
1307 drop:
1308 return 0;
1309 }
1310
1311
1312 /*
1313 * The three way handshake has completed - we got a valid synack -
1314 * now create the new socket.
1315 */
1316 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1317 struct request_sock *req,
1318 struct dst_entry *dst)
1319 {
1320 struct inet_request_sock *ireq;
1321 struct inet_sock *newinet;
1322 struct tcp_sock *newtp;
1323 struct sock *newsk;
1324 #ifdef CONFIG_TCP_MD5SIG
1325 struct tcp_md5sig_key *key;
1326 #endif
1327
1328 if (sk_acceptq_is_full(sk))
1329 goto exit_overflow;
1330
1331 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1332 goto exit;
1333
1334 newsk = tcp_create_openreq_child(sk, req, skb);
1335 if (!newsk)
1336 goto exit;
1337
1338 newsk->sk_gso_type = SKB_GSO_TCPV4;
1339 sk_setup_caps(newsk, dst);
1340
1341 newtp = tcp_sk(newsk);
1342 newinet = inet_sk(newsk);
1343 ireq = inet_rsk(req);
1344 newinet->daddr = ireq->rmt_addr;
1345 newinet->rcv_saddr = ireq->loc_addr;
1346 newinet->saddr = ireq->loc_addr;
1347 newinet->opt = ireq->opt;
1348 ireq->opt = NULL;
1349 newinet->mc_index = inet_iif(skb);
1350 newinet->mc_ttl = ip_hdr(skb)->ttl;
1351 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1352 if (newinet->opt)
1353 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1354 newinet->id = newtp->write_seq ^ jiffies;
1355
1356 tcp_mtup_init(newsk);
1357 tcp_sync_mss(newsk, dst_mtu(dst));
1358 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1359 if (tcp_sk(sk)->rx_opt.user_mss &&
1360 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1361 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1362
1363 tcp_initialize_rcv_mss(newsk);
1364
1365 #ifdef CONFIG_TCP_MD5SIG
1366 /* Copy over the MD5 key from the original socket */
1367 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
1368 /*
1369 * We're using one, so create a matching key
1370 * on the newsk structure. If we fail to get
1371 * memory, then we end up not copying the key
1372 * across. Shucks.
1373 */
1374 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1375 if (newkey != NULL)
1376 tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
1377 newkey, key->keylen);
1378 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1379 }
1380 #endif
1381
1382 __inet_hash_nolisten(newsk);
1383 __inet_inherit_port(sk, newsk);
1384
1385 return newsk;
1386
1387 exit_overflow:
1388 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1389 exit:
1390 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1391 dst_release(dst);
1392 return NULL;
1393 }
1394
1395 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1396 {
1397 struct tcphdr *th = tcp_hdr(skb);
1398 const struct iphdr *iph = ip_hdr(skb);
1399 struct sock *nsk;
1400 struct request_sock **prev;
1401 /* Find possible connection requests. */
1402 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1403 iph->saddr, iph->daddr);
1404 if (req)
1405 return tcp_check_req(sk, skb, req, prev);
1406
1407 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1408 th->source, iph->daddr, th->dest, inet_iif(skb));
1409
1410 if (nsk) {
1411 if (nsk->sk_state != TCP_TIME_WAIT) {
1412 bh_lock_sock(nsk);
1413 return nsk;
1414 }
1415 inet_twsk_put(inet_twsk(nsk));
1416 return NULL;
1417 }
1418
1419 #ifdef CONFIG_SYN_COOKIES
1420 if (!th->rst && !th->syn && th->ack)
1421 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1422 #endif
1423 return sk;
1424 }
1425
1426 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1427 {
1428 const struct iphdr *iph = ip_hdr(skb);
1429
1430 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1431 if (!tcp_v4_check(skb->len, iph->saddr,
1432 iph->daddr, skb->csum)) {
1433 skb->ip_summed = CHECKSUM_UNNECESSARY;
1434 return 0;
1435 }
1436 }
1437
1438 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1439 skb->len, IPPROTO_TCP, 0);
1440
1441 if (skb->len <= 76) {
1442 return __skb_checksum_complete(skb);
1443 }
1444 return 0;
1445 }
1446
1447
1448 /* The socket must have it's spinlock held when we get
1449 * here.
1450 *
1451 * We have a potential double-lock case here, so even when
1452 * doing backlog processing we use the BH locking scheme.
1453 * This is because we cannot sleep with the original spinlock
1454 * held.
1455 */
1456 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1457 {
1458 struct sock *rsk;
1459 #ifdef CONFIG_TCP_MD5SIG
1460 /*
1461 * We really want to reject the packet as early as possible
1462 * if:
1463 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1464 * o There is an MD5 option and we're not expecting one
1465 */
1466 if (tcp_v4_inbound_md5_hash(sk, skb))
1467 goto discard;
1468 #endif
1469
1470 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1471 TCP_CHECK_TIMER(sk);
1472 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1473 rsk = sk;
1474 goto reset;
1475 }
1476 TCP_CHECK_TIMER(sk);
1477 return 0;
1478 }
1479
1480 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1481 goto csum_err;
1482
1483 if (sk->sk_state == TCP_LISTEN) {
1484 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1485 if (!nsk)
1486 goto discard;
1487
1488 if (nsk != sk) {
1489 if (tcp_child_process(sk, nsk, skb)) {
1490 rsk = nsk;
1491 goto reset;
1492 }
1493 return 0;
1494 }
1495 }
1496
1497 TCP_CHECK_TIMER(sk);
1498 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1499 rsk = sk;
1500 goto reset;
1501 }
1502 TCP_CHECK_TIMER(sk);
1503 return 0;
1504
1505 reset:
1506 tcp_v4_send_reset(rsk, skb);
1507 discard:
1508 kfree_skb(skb);
1509 /* Be careful here. If this function gets more complicated and
1510 * gcc suffers from register pressure on the x86, sk (in %ebx)
1511 * might be destroyed here. This current version compiles correctly,
1512 * but you have been warned.
1513 */
1514 return 0;
1515
1516 csum_err:
1517 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1518 goto discard;
1519 }
1520
1521 /*
1522 * From tcp_input.c
1523 */
1524
1525 int tcp_v4_rcv(struct sk_buff *skb)
1526 {
1527 const struct iphdr *iph;
1528 struct tcphdr *th;
1529 struct sock *sk;
1530 int ret;
1531 struct net *net = dev_net(skb->dev);
1532
1533 if (skb->pkt_type != PACKET_HOST)
1534 goto discard_it;
1535
1536 /* Count it even if it's bad */
1537 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1538
1539 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1540 goto discard_it;
1541
1542 th = tcp_hdr(skb);
1543
1544 if (th->doff < sizeof(struct tcphdr) / 4)
1545 goto bad_packet;
1546 if (!pskb_may_pull(skb, th->doff * 4))
1547 goto discard_it;
1548
1549 /* An explanation is required here, I think.
1550 * Packet length and doff are validated by header prediction,
1551 * provided case of th->doff==0 is eliminated.
1552 * So, we defer the checks. */
1553 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1554 goto bad_packet;
1555
1556 th = tcp_hdr(skb);
1557 iph = ip_hdr(skb);
1558 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1559 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1560 skb->len - th->doff * 4);
1561 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1562 TCP_SKB_CB(skb)->when = 0;
1563 TCP_SKB_CB(skb)->flags = iph->tos;
1564 TCP_SKB_CB(skb)->sacked = 0;
1565
1566 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1567 if (!sk)
1568 goto no_tcp_socket;
1569
1570 process:
1571 if (sk->sk_state == TCP_TIME_WAIT)
1572 goto do_time_wait;
1573
1574 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1575 goto discard_and_relse;
1576 nf_reset(skb);
1577
1578 if (sk_filter(sk, skb))
1579 goto discard_and_relse;
1580
1581 skb->dev = NULL;
1582
1583 bh_lock_sock_nested(sk);
1584 ret = 0;
1585 if (!sock_owned_by_user(sk)) {
1586 #ifdef CONFIG_NET_DMA
1587 struct tcp_sock *tp = tcp_sk(sk);
1588 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1589 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1590 if (tp->ucopy.dma_chan)
1591 ret = tcp_v4_do_rcv(sk, skb);
1592 else
1593 #endif
1594 {
1595 if (!tcp_prequeue(sk, skb))
1596 ret = tcp_v4_do_rcv(sk, skb);
1597 }
1598 } else
1599 sk_add_backlog(sk, skb);
1600 bh_unlock_sock(sk);
1601
1602 sock_put(sk);
1603
1604 return ret;
1605
1606 no_tcp_socket:
1607 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1608 goto discard_it;
1609
1610 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1611 bad_packet:
1612 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1613 } else {
1614 tcp_v4_send_reset(NULL, skb);
1615 }
1616
1617 discard_it:
1618 /* Discard frame. */
1619 kfree_skb(skb);
1620 return 0;
1621
1622 discard_and_relse:
1623 sock_put(sk);
1624 goto discard_it;
1625
1626 do_time_wait:
1627 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1628 inet_twsk_put(inet_twsk(sk));
1629 goto discard_it;
1630 }
1631
1632 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1633 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1634 inet_twsk_put(inet_twsk(sk));
1635 goto discard_it;
1636 }
1637 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1638 case TCP_TW_SYN: {
1639 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1640 &tcp_hashinfo,
1641 iph->daddr, th->dest,
1642 inet_iif(skb));
1643 if (sk2) {
1644 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1645 inet_twsk_put(inet_twsk(sk));
1646 sk = sk2;
1647 goto process;
1648 }
1649 /* Fall through to ACK */
1650 }
1651 case TCP_TW_ACK:
1652 tcp_v4_timewait_ack(sk, skb);
1653 break;
1654 case TCP_TW_RST:
1655 goto no_tcp_socket;
1656 case TCP_TW_SUCCESS:;
1657 }
1658 goto discard_it;
1659 }
1660
1661 /* VJ's idea. Save last timestamp seen from this destination
1662 * and hold it at least for normal timewait interval to use for duplicate
1663 * segment detection in subsequent connections, before they enter synchronized
1664 * state.
1665 */
1666
1667 int tcp_v4_remember_stamp(struct sock *sk)
1668 {
1669 struct inet_sock *inet = inet_sk(sk);
1670 struct tcp_sock *tp = tcp_sk(sk);
1671 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1672 struct inet_peer *peer = NULL;
1673 int release_it = 0;
1674
1675 if (!rt || rt->rt_dst != inet->daddr) {
1676 peer = inet_getpeer(inet->daddr, 1);
1677 release_it = 1;
1678 } else {
1679 if (!rt->peer)
1680 rt_bind_peer(rt, 1);
1681 peer = rt->peer;
1682 }
1683
1684 if (peer) {
1685 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1686 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1687 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1688 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1689 peer->tcp_ts = tp->rx_opt.ts_recent;
1690 }
1691 if (release_it)
1692 inet_putpeer(peer);
1693 return 1;
1694 }
1695
1696 return 0;
1697 }
1698
1699 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1700 {
1701 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1702
1703 if (peer) {
1704 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1705
1706 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1707 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1708 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1709 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1710 peer->tcp_ts = tcptw->tw_ts_recent;
1711 }
1712 inet_putpeer(peer);
1713 return 1;
1714 }
1715
1716 return 0;
1717 }
1718
1719 struct inet_connection_sock_af_ops ipv4_specific = {
1720 .queue_xmit = ip_queue_xmit,
1721 .send_check = tcp_v4_send_check,
1722 .rebuild_header = inet_sk_rebuild_header,
1723 .conn_request = tcp_v4_conn_request,
1724 .syn_recv_sock = tcp_v4_syn_recv_sock,
1725 .remember_stamp = tcp_v4_remember_stamp,
1726 .net_header_len = sizeof(struct iphdr),
1727 .setsockopt = ip_setsockopt,
1728 .getsockopt = ip_getsockopt,
1729 .addr2sockaddr = inet_csk_addr2sockaddr,
1730 .sockaddr_len = sizeof(struct sockaddr_in),
1731 .bind_conflict = inet_csk_bind_conflict,
1732 #ifdef CONFIG_COMPAT
1733 .compat_setsockopt = compat_ip_setsockopt,
1734 .compat_getsockopt = compat_ip_getsockopt,
1735 #endif
1736 };
1737
1738 #ifdef CONFIG_TCP_MD5SIG
1739 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1740 .md5_lookup = tcp_v4_md5_lookup,
1741 .calc_md5_hash = tcp_v4_md5_hash_skb,
1742 .md5_add = tcp_v4_md5_add_func,
1743 .md5_parse = tcp_v4_parse_md5_keys,
1744 };
1745 #endif
1746
1747 /* NOTE: A lot of things set to zero explicitly by call to
1748 * sk_alloc() so need not be done here.
1749 */
1750 static int tcp_v4_init_sock(struct sock *sk)
1751 {
1752 struct inet_connection_sock *icsk = inet_csk(sk);
1753 struct tcp_sock *tp = tcp_sk(sk);
1754
1755 skb_queue_head_init(&tp->out_of_order_queue);
1756 tcp_init_xmit_timers(sk);
1757 tcp_prequeue_init(tp);
1758
1759 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1760 tp->mdev = TCP_TIMEOUT_INIT;
1761
1762 /* So many TCP implementations out there (incorrectly) count the
1763 * initial SYN frame in their delayed-ACK and congestion control
1764 * algorithms that we must have the following bandaid to talk
1765 * efficiently to them. -DaveM
1766 */
1767 tp->snd_cwnd = 2;
1768
1769 /* See draft-stevens-tcpca-spec-01 for discussion of the
1770 * initialization of these values.
1771 */
1772 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1773 tp->snd_cwnd_clamp = ~0;
1774 tp->mss_cache = 536;
1775
1776 tp->reordering = sysctl_tcp_reordering;
1777 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1778
1779 sk->sk_state = TCP_CLOSE;
1780
1781 sk->sk_write_space = sk_stream_write_space;
1782 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1783
1784 icsk->icsk_af_ops = &ipv4_specific;
1785 icsk->icsk_sync_mss = tcp_sync_mss;
1786 #ifdef CONFIG_TCP_MD5SIG
1787 tp->af_specific = &tcp_sock_ipv4_specific;
1788 #endif
1789
1790 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1791 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1792
1793 local_bh_disable();
1794 percpu_counter_inc(&tcp_sockets_allocated);
1795 local_bh_enable();
1796
1797 return 0;
1798 }
1799
1800 void tcp_v4_destroy_sock(struct sock *sk)
1801 {
1802 struct tcp_sock *tp = tcp_sk(sk);
1803
1804 tcp_clear_xmit_timers(sk);
1805
1806 tcp_cleanup_congestion_control(sk);
1807
1808 /* Cleanup up the write buffer. */
1809 tcp_write_queue_purge(sk);
1810
1811 /* Cleans up our, hopefully empty, out_of_order_queue. */
1812 __skb_queue_purge(&tp->out_of_order_queue);
1813
1814 #ifdef CONFIG_TCP_MD5SIG
1815 /* Clean up the MD5 key list, if any */
1816 if (tp->md5sig_info) {
1817 tcp_v4_clear_md5_list(sk);
1818 kfree(tp->md5sig_info);
1819 tp->md5sig_info = NULL;
1820 }
1821 #endif
1822
1823 #ifdef CONFIG_NET_DMA
1824 /* Cleans up our sk_async_wait_queue */
1825 __skb_queue_purge(&sk->sk_async_wait_queue);
1826 #endif
1827
1828 /* Clean prequeue, it must be empty really */
1829 __skb_queue_purge(&tp->ucopy.prequeue);
1830
1831 /* Clean up a referenced TCP bind bucket. */
1832 if (inet_csk(sk)->icsk_bind_hash)
1833 inet_put_port(sk);
1834
1835 /*
1836 * If sendmsg cached page exists, toss it.
1837 */
1838 if (sk->sk_sndmsg_page) {
1839 __free_page(sk->sk_sndmsg_page);
1840 sk->sk_sndmsg_page = NULL;
1841 }
1842
1843 percpu_counter_dec(&tcp_sockets_allocated);
1844 }
1845
1846 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1847
1848 #ifdef CONFIG_PROC_FS
1849 /* Proc filesystem TCP sock list dumping. */
1850
1851 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
1852 {
1853 return hlist_nulls_empty(head) ? NULL :
1854 list_entry(head->first, struct inet_timewait_sock, tw_node);
1855 }
1856
1857 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1858 {
1859 return !is_a_nulls(tw->tw_node.next) ?
1860 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1861 }
1862
1863 static void *listening_get_next(struct seq_file *seq, void *cur)
1864 {
1865 struct inet_connection_sock *icsk;
1866 struct hlist_nulls_node *node;
1867 struct sock *sk = cur;
1868 struct inet_listen_hashbucket *ilb;
1869 struct tcp_iter_state *st = seq->private;
1870 struct net *net = seq_file_net(seq);
1871
1872 if (!sk) {
1873 st->bucket = 0;
1874 ilb = &tcp_hashinfo.listening_hash[0];
1875 spin_lock_bh(&ilb->lock);
1876 sk = sk_nulls_head(&ilb->head);
1877 goto get_sk;
1878 }
1879 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1880 ++st->num;
1881
1882 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1883 struct request_sock *req = cur;
1884
1885 icsk = inet_csk(st->syn_wait_sk);
1886 req = req->dl_next;
1887 while (1) {
1888 while (req) {
1889 if (req->rsk_ops->family == st->family) {
1890 cur = req;
1891 goto out;
1892 }
1893 req = req->dl_next;
1894 }
1895 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1896 break;
1897 get_req:
1898 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1899 }
1900 sk = sk_next(st->syn_wait_sk);
1901 st->state = TCP_SEQ_STATE_LISTENING;
1902 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1903 } else {
1904 icsk = inet_csk(sk);
1905 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1906 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1907 goto start_req;
1908 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1909 sk = sk_next(sk);
1910 }
1911 get_sk:
1912 sk_nulls_for_each_from(sk, node) {
1913 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
1914 cur = sk;
1915 goto out;
1916 }
1917 icsk = inet_csk(sk);
1918 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1919 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1920 start_req:
1921 st->uid = sock_i_uid(sk);
1922 st->syn_wait_sk = sk;
1923 st->state = TCP_SEQ_STATE_OPENREQ;
1924 st->sbucket = 0;
1925 goto get_req;
1926 }
1927 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1928 }
1929 spin_unlock_bh(&ilb->lock);
1930 if (++st->bucket < INET_LHTABLE_SIZE) {
1931 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1932 spin_lock_bh(&ilb->lock);
1933 sk = sk_nulls_head(&ilb->head);
1934 goto get_sk;
1935 }
1936 cur = NULL;
1937 out:
1938 return cur;
1939 }
1940
1941 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1942 {
1943 void *rc = listening_get_next(seq, NULL);
1944
1945 while (rc && *pos) {
1946 rc = listening_get_next(seq, rc);
1947 --*pos;
1948 }
1949 return rc;
1950 }
1951
1952 static inline int empty_bucket(struct tcp_iter_state *st)
1953 {
1954 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
1955 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
1956 }
1957
1958 static void *established_get_first(struct seq_file *seq)
1959 {
1960 struct tcp_iter_state *st = seq->private;
1961 struct net *net = seq_file_net(seq);
1962 void *rc = NULL;
1963
1964 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1965 struct sock *sk;
1966 struct hlist_nulls_node *node;
1967 struct inet_timewait_sock *tw;
1968 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1969
1970 /* Lockless fast path for the common case of empty buckets */
1971 if (empty_bucket(st))
1972 continue;
1973
1974 spin_lock_bh(lock);
1975 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1976 if (sk->sk_family != st->family ||
1977 !net_eq(sock_net(sk), net)) {
1978 continue;
1979 }
1980 rc = sk;
1981 goto out;
1982 }
1983 st->state = TCP_SEQ_STATE_TIME_WAIT;
1984 inet_twsk_for_each(tw, node,
1985 &tcp_hashinfo.ehash[st->bucket].twchain) {
1986 if (tw->tw_family != st->family ||
1987 !net_eq(twsk_net(tw), net)) {
1988 continue;
1989 }
1990 rc = tw;
1991 goto out;
1992 }
1993 spin_unlock_bh(lock);
1994 st->state = TCP_SEQ_STATE_ESTABLISHED;
1995 }
1996 out:
1997 return rc;
1998 }
1999
2000 static void *established_get_next(struct seq_file *seq, void *cur)
2001 {
2002 struct sock *sk = cur;
2003 struct inet_timewait_sock *tw;
2004 struct hlist_nulls_node *node;
2005 struct tcp_iter_state *st = seq->private;
2006 struct net *net = seq_file_net(seq);
2007
2008 ++st->num;
2009
2010 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2011 tw = cur;
2012 tw = tw_next(tw);
2013 get_tw:
2014 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2015 tw = tw_next(tw);
2016 }
2017 if (tw) {
2018 cur = tw;
2019 goto out;
2020 }
2021 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2022 st->state = TCP_SEQ_STATE_ESTABLISHED;
2023
2024 /* Look for next non empty bucket */
2025 while (++st->bucket < tcp_hashinfo.ehash_size &&
2026 empty_bucket(st))
2027 ;
2028 if (st->bucket >= tcp_hashinfo.ehash_size)
2029 return NULL;
2030
2031 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2032 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2033 } else
2034 sk = sk_nulls_next(sk);
2035
2036 sk_nulls_for_each_from(sk, node) {
2037 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2038 goto found;
2039 }
2040
2041 st->state = TCP_SEQ_STATE_TIME_WAIT;
2042 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2043 goto get_tw;
2044 found:
2045 cur = sk;
2046 out:
2047 return cur;
2048 }
2049
2050 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2051 {
2052 void *rc = established_get_first(seq);
2053
2054 while (rc && pos) {
2055 rc = established_get_next(seq, rc);
2056 --pos;
2057 }
2058 return rc;
2059 }
2060
2061 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2062 {
2063 void *rc;
2064 struct tcp_iter_state *st = seq->private;
2065
2066 st->state = TCP_SEQ_STATE_LISTENING;
2067 rc = listening_get_idx(seq, &pos);
2068
2069 if (!rc) {
2070 st->state = TCP_SEQ_STATE_ESTABLISHED;
2071 rc = established_get_idx(seq, pos);
2072 }
2073
2074 return rc;
2075 }
2076
2077 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2078 {
2079 struct tcp_iter_state *st = seq->private;
2080 st->state = TCP_SEQ_STATE_LISTENING;
2081 st->num = 0;
2082 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2083 }
2084
2085 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2086 {
2087 void *rc = NULL;
2088 struct tcp_iter_state *st;
2089
2090 if (v == SEQ_START_TOKEN) {
2091 rc = tcp_get_idx(seq, 0);
2092 goto out;
2093 }
2094 st = seq->private;
2095
2096 switch (st->state) {
2097 case TCP_SEQ_STATE_OPENREQ:
2098 case TCP_SEQ_STATE_LISTENING:
2099 rc = listening_get_next(seq, v);
2100 if (!rc) {
2101 st->state = TCP_SEQ_STATE_ESTABLISHED;
2102 rc = established_get_first(seq);
2103 }
2104 break;
2105 case TCP_SEQ_STATE_ESTABLISHED:
2106 case TCP_SEQ_STATE_TIME_WAIT:
2107 rc = established_get_next(seq, v);
2108 break;
2109 }
2110 out:
2111 ++*pos;
2112 return rc;
2113 }
2114
2115 static void tcp_seq_stop(struct seq_file *seq, void *v)
2116 {
2117 struct tcp_iter_state *st = seq->private;
2118
2119 switch (st->state) {
2120 case TCP_SEQ_STATE_OPENREQ:
2121 if (v) {
2122 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2123 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2124 }
2125 case TCP_SEQ_STATE_LISTENING:
2126 if (v != SEQ_START_TOKEN)
2127 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2128 break;
2129 case TCP_SEQ_STATE_TIME_WAIT:
2130 case TCP_SEQ_STATE_ESTABLISHED:
2131 if (v)
2132 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2133 break;
2134 }
2135 }
2136
2137 static int tcp_seq_open(struct inode *inode, struct file *file)
2138 {
2139 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2140 struct tcp_iter_state *s;
2141 int err;
2142
2143 err = seq_open_net(inode, file, &afinfo->seq_ops,
2144 sizeof(struct tcp_iter_state));
2145 if (err < 0)
2146 return err;
2147
2148 s = ((struct seq_file *)file->private_data)->private;
2149 s->family = afinfo->family;
2150 return 0;
2151 }
2152
2153 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2154 {
2155 int rc = 0;
2156 struct proc_dir_entry *p;
2157
2158 afinfo->seq_fops.open = tcp_seq_open;
2159 afinfo->seq_fops.read = seq_read;
2160 afinfo->seq_fops.llseek = seq_lseek;
2161 afinfo->seq_fops.release = seq_release_net;
2162
2163 afinfo->seq_ops.start = tcp_seq_start;
2164 afinfo->seq_ops.next = tcp_seq_next;
2165 afinfo->seq_ops.stop = tcp_seq_stop;
2166
2167 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2168 &afinfo->seq_fops, afinfo);
2169 if (!p)
2170 rc = -ENOMEM;
2171 return rc;
2172 }
2173
2174 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2175 {
2176 proc_net_remove(net, afinfo->name);
2177 }
2178
2179 static void get_openreq4(struct sock *sk, struct request_sock *req,
2180 struct seq_file *f, int i, int uid, int *len)
2181 {
2182 const struct inet_request_sock *ireq = inet_rsk(req);
2183 int ttd = req->expires - jiffies;
2184
2185 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2186 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
2187 i,
2188 ireq->loc_addr,
2189 ntohs(inet_sk(sk)->sport),
2190 ireq->rmt_addr,
2191 ntohs(ireq->rmt_port),
2192 TCP_SYN_RECV,
2193 0, 0, /* could print option size, but that is af dependent. */
2194 1, /* timers active (only the expire timer) */
2195 jiffies_to_clock_t(ttd),
2196 req->retrans,
2197 uid,
2198 0, /* non standard timer */
2199 0, /* open_requests have no inode */
2200 atomic_read(&sk->sk_refcnt),
2201 req,
2202 len);
2203 }
2204
2205 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2206 {
2207 int timer_active;
2208 unsigned long timer_expires;
2209 struct tcp_sock *tp = tcp_sk(sk);
2210 const struct inet_connection_sock *icsk = inet_csk(sk);
2211 struct inet_sock *inet = inet_sk(sk);
2212 __be32 dest = inet->daddr;
2213 __be32 src = inet->rcv_saddr;
2214 __u16 destp = ntohs(inet->dport);
2215 __u16 srcp = ntohs(inet->sport);
2216
2217 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2218 timer_active = 1;
2219 timer_expires = icsk->icsk_timeout;
2220 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2221 timer_active = 4;
2222 timer_expires = icsk->icsk_timeout;
2223 } else if (timer_pending(&sk->sk_timer)) {
2224 timer_active = 2;
2225 timer_expires = sk->sk_timer.expires;
2226 } else {
2227 timer_active = 0;
2228 timer_expires = jiffies;
2229 }
2230
2231 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2232 "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2233 i, src, srcp, dest, destp, sk->sk_state,
2234 tp->write_seq - tp->snd_una,
2235 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2236 (tp->rcv_nxt - tp->copied_seq),
2237 timer_active,
2238 jiffies_to_clock_t(timer_expires - jiffies),
2239 icsk->icsk_retransmits,
2240 sock_i_uid(sk),
2241 icsk->icsk_probes_out,
2242 sock_i_ino(sk),
2243 atomic_read(&sk->sk_refcnt), sk,
2244 jiffies_to_clock_t(icsk->icsk_rto),
2245 jiffies_to_clock_t(icsk->icsk_ack.ato),
2246 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2247 tp->snd_cwnd,
2248 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh,
2249 len);
2250 }
2251
2252 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2253 struct seq_file *f, int i, int *len)
2254 {
2255 __be32 dest, src;
2256 __u16 destp, srcp;
2257 int ttd = tw->tw_ttd - jiffies;
2258
2259 if (ttd < 0)
2260 ttd = 0;
2261
2262 dest = tw->tw_daddr;
2263 src = tw->tw_rcv_saddr;
2264 destp = ntohs(tw->tw_dport);
2265 srcp = ntohs(tw->tw_sport);
2266
2267 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2268 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
2269 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2270 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2271 atomic_read(&tw->tw_refcnt), tw, len);
2272 }
2273
2274 #define TMPSZ 150
2275
2276 static int tcp4_seq_show(struct seq_file *seq, void *v)
2277 {
2278 struct tcp_iter_state *st;
2279 int len;
2280
2281 if (v == SEQ_START_TOKEN) {
2282 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2283 " sl local_address rem_address st tx_queue "
2284 "rx_queue tr tm->when retrnsmt uid timeout "
2285 "inode");
2286 goto out;
2287 }
2288 st = seq->private;
2289
2290 switch (st->state) {
2291 case TCP_SEQ_STATE_LISTENING:
2292 case TCP_SEQ_STATE_ESTABLISHED:
2293 get_tcp4_sock(v, seq, st->num, &len);
2294 break;
2295 case TCP_SEQ_STATE_OPENREQ:
2296 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2297 break;
2298 case TCP_SEQ_STATE_TIME_WAIT:
2299 get_timewait4_sock(v, seq, st->num, &len);
2300 break;
2301 }
2302 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2303 out:
2304 return 0;
2305 }
2306
2307 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2308 .name = "tcp",
2309 .family = AF_INET,
2310 .seq_fops = {
2311 .owner = THIS_MODULE,
2312 },
2313 .seq_ops = {
2314 .show = tcp4_seq_show,
2315 },
2316 };
2317
2318 static int tcp4_proc_init_net(struct net *net)
2319 {
2320 return tcp_proc_register(net, &tcp4_seq_afinfo);
2321 }
2322
2323 static void tcp4_proc_exit_net(struct net *net)
2324 {
2325 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2326 }
2327
2328 static struct pernet_operations tcp4_net_ops = {
2329 .init = tcp4_proc_init_net,
2330 .exit = tcp4_proc_exit_net,
2331 };
2332
2333 int __init tcp4_proc_init(void)
2334 {
2335 return register_pernet_subsys(&tcp4_net_ops);
2336 }
2337
2338 void tcp4_proc_exit(void)
2339 {
2340 unregister_pernet_subsys(&tcp4_net_ops);
2341 }
2342 #endif /* CONFIG_PROC_FS */
2343
2344 struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2345 {
2346 struct iphdr *iph = ip_hdr(skb);
2347
2348 switch (skb->ip_summed) {
2349 case CHECKSUM_COMPLETE:
2350 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
2351 skb->csum)) {
2352 skb->ip_summed = CHECKSUM_UNNECESSARY;
2353 break;
2354 }
2355
2356 /* fall through */
2357 case CHECKSUM_NONE:
2358 NAPI_GRO_CB(skb)->flush = 1;
2359 return NULL;
2360 }
2361
2362 return tcp_gro_receive(head, skb);
2363 }
2364 EXPORT_SYMBOL(tcp4_gro_receive);
2365
2366 int tcp4_gro_complete(struct sk_buff *skb)
2367 {
2368 struct iphdr *iph = ip_hdr(skb);
2369 struct tcphdr *th = tcp_hdr(skb);
2370
2371 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
2372 iph->saddr, iph->daddr, 0);
2373 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
2374
2375 return tcp_gro_complete(skb);
2376 }
2377 EXPORT_SYMBOL(tcp4_gro_complete);
2378
2379 struct proto tcp_prot = {
2380 .name = "TCP",
2381 .owner = THIS_MODULE,
2382 .close = tcp_close,
2383 .connect = tcp_v4_connect,
2384 .disconnect = tcp_disconnect,
2385 .accept = inet_csk_accept,
2386 .ioctl = tcp_ioctl,
2387 .init = tcp_v4_init_sock,
2388 .destroy = tcp_v4_destroy_sock,
2389 .shutdown = tcp_shutdown,
2390 .setsockopt = tcp_setsockopt,
2391 .getsockopt = tcp_getsockopt,
2392 .recvmsg = tcp_recvmsg,
2393 .backlog_rcv = tcp_v4_do_rcv,
2394 .hash = inet_hash,
2395 .unhash = inet_unhash,
2396 .get_port = inet_csk_get_port,
2397 .enter_memory_pressure = tcp_enter_memory_pressure,
2398 .sockets_allocated = &tcp_sockets_allocated,
2399 .orphan_count = &tcp_orphan_count,
2400 .memory_allocated = &tcp_memory_allocated,
2401 .memory_pressure = &tcp_memory_pressure,
2402 .sysctl_mem = sysctl_tcp_mem,
2403 .sysctl_wmem = sysctl_tcp_wmem,
2404 .sysctl_rmem = sysctl_tcp_rmem,
2405 .max_header = MAX_TCP_HEADER,
2406 .obj_size = sizeof(struct tcp_sock),
2407 .slab_flags = SLAB_DESTROY_BY_RCU,
2408 .twsk_prot = &tcp_timewait_sock_ops,
2409 .rsk_prot = &tcp_request_sock_ops,
2410 .h.hashinfo = &tcp_hashinfo,
2411 #ifdef CONFIG_COMPAT
2412 .compat_setsockopt = compat_tcp_setsockopt,
2413 .compat_getsockopt = compat_tcp_getsockopt,
2414 #endif
2415 };
2416
2417
2418 static int __net_init tcp_sk_init(struct net *net)
2419 {
2420 return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2421 PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2422 }
2423
2424 static void __net_exit tcp_sk_exit(struct net *net)
2425 {
2426 inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2427 inet_twsk_purge(net, &tcp_hashinfo, &tcp_death_row, AF_INET);
2428 }
2429
2430 static struct pernet_operations __net_initdata tcp_sk_ops = {
2431 .init = tcp_sk_init,
2432 .exit = tcp_sk_exit,
2433 };
2434
2435 void __init tcp_v4_init(void)
2436 {
2437 inet_hashinfo_init(&tcp_hashinfo);
2438 if (register_pernet_subsys(&tcp_sk_ops))
2439 panic("Failed to create the TCP control socket.\n");
2440 }
2441
2442 EXPORT_SYMBOL(ipv4_specific);
2443 EXPORT_SYMBOL(tcp_hashinfo);
2444 EXPORT_SYMBOL(tcp_prot);
2445 EXPORT_SYMBOL(tcp_v4_conn_request);
2446 EXPORT_SYMBOL(tcp_v4_connect);
2447 EXPORT_SYMBOL(tcp_v4_do_rcv);
2448 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2449 EXPORT_SYMBOL(tcp_v4_send_check);
2450 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2451
2452 #ifdef CONFIG_PROC_FS
2453 EXPORT_SYMBOL(tcp_proc_register);
2454 EXPORT_SYMBOL(tcp_proc_unregister);
2455 #endif
2456 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2457
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