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tcp: Like icmp use register_pernet_subsys
[deliverable/linux.git] / net / ipv4 / tcp_ipv4.c
1 /*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Implementation of the Transmission Control Protocol(TCP).
7 *
8 * IPv4 specific functions
9 *
10 *
11 * code split from:
12 * linux/ipv4/tcp.c
13 * linux/ipv4/tcp_input.c
14 * linux/ipv4/tcp_output.c
15 *
16 * See tcp.c for author information
17 *
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
22 */
23
24 /*
25 * Changes:
26 * David S. Miller : New socket lookup architecture.
27 * This code is dedicated to John Dyson.
28 * David S. Miller : Change semantics of established hash,
29 * half is devoted to TIME_WAIT sockets
30 * and the rest go in the other half.
31 * Andi Kleen : Add support for syncookies and fixed
32 * some bugs: ip options weren't passed to
33 * the TCP layer, missed a check for an
34 * ACK bit.
35 * Andi Kleen : Implemented fast path mtu discovery.
36 * Fixed many serious bugs in the
37 * request_sock handling and moved
38 * most of it into the af independent code.
39 * Added tail drop and some other bugfixes.
40 * Added new listen semantics.
41 * Mike McLagan : Routing by source
42 * Juan Jose Ciarlante: ip_dynaddr bits
43 * Andi Kleen: various fixes.
44 * Vitaly E. Lavrov : Transparent proxy revived after year
45 * coma.
46 * Andi Kleen : Fix new listen.
47 * Andi Kleen : Fix accept error reporting.
48 * YOSHIFUJI Hideaki @USAGI and: Support IPV6_V6ONLY socket option, which
49 * Alexey Kuznetsov allow both IPv4 and IPv6 sockets to bind
50 * a single port at the same time.
51 */
52
53
54 #include <linux/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 if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
1230 /* Some OSes (unknown ones, but I see them on web server, which
1231 * contains information interesting only for windows'
1232 * users) do not send their stamp in SYN. It is easy case.
1233 * We simply do not advertise TS support.
1234 */
1235 tmp_opt.saw_tstamp = 0;
1236 tmp_opt.tstamp_ok = 0;
1237 }
1238 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1239
1240 tcp_openreq_init(req, &tmp_opt, skb);
1241
1242 if (security_inet_conn_request(sk, skb, req))
1243 goto drop_and_free;
1244
1245 ireq = inet_rsk(req);
1246 ireq->loc_addr = daddr;
1247 ireq->rmt_addr = saddr;
1248 ireq->no_srccheck = inet_sk(sk)->transparent;
1249 ireq->opt = tcp_v4_save_options(sk, skb);
1250 if (!want_cookie)
1251 TCP_ECN_create_request(req, tcp_hdr(skb));
1252
1253 if (want_cookie) {
1254 #ifdef CONFIG_SYN_COOKIES
1255 syn_flood_warning(skb);
1256 req->cookie_ts = tmp_opt.tstamp_ok;
1257 #endif
1258 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1259 } else if (!isn) {
1260 struct inet_peer *peer = NULL;
1261
1262 /* VJ's idea. We save last timestamp seen
1263 * from the destination in peer table, when entering
1264 * state TIME-WAIT, and check against it before
1265 * accepting new connection request.
1266 *
1267 * If "isn" is not zero, this request hit alive
1268 * timewait bucket, so that all the necessary checks
1269 * are made in the function processing timewait state.
1270 */
1271 if (tmp_opt.saw_tstamp &&
1272 tcp_death_row.sysctl_tw_recycle &&
1273 (dst = inet_csk_route_req(sk, req)) != NULL &&
1274 (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
1275 peer->v4daddr == saddr) {
1276 if (get_seconds() < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
1277 (s32)(peer->tcp_ts - req->ts_recent) >
1278 TCP_PAWS_WINDOW) {
1279 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1280 goto drop_and_release;
1281 }
1282 }
1283 /* Kill the following clause, if you dislike this way. */
1284 else if (!sysctl_tcp_syncookies &&
1285 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1286 (sysctl_max_syn_backlog >> 2)) &&
1287 (!peer || !peer->tcp_ts_stamp) &&
1288 (!dst || !dst_metric(dst, RTAX_RTT))) {
1289 /* Without syncookies last quarter of
1290 * backlog is filled with destinations,
1291 * proven to be alive.
1292 * It means that we continue to communicate
1293 * to destinations, already remembered
1294 * to the moment of synflood.
1295 */
1296 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
1297 &saddr, ntohs(tcp_hdr(skb)->source));
1298 goto drop_and_release;
1299 }
1300
1301 isn = tcp_v4_init_sequence(skb);
1302 }
1303 tcp_rsk(req)->snt_isn = isn;
1304
1305 if (__tcp_v4_send_synack(sk, req, dst) || want_cookie)
1306 goto drop_and_free;
1307
1308 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1309 return 0;
1310
1311 drop_and_release:
1312 dst_release(dst);
1313 drop_and_free:
1314 reqsk_free(req);
1315 drop:
1316 return 0;
1317 }
1318
1319
1320 /*
1321 * The three way handshake has completed - we got a valid synack -
1322 * now create the new socket.
1323 */
1324 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1325 struct request_sock *req,
1326 struct dst_entry *dst)
1327 {
1328 struct inet_request_sock *ireq;
1329 struct inet_sock *newinet;
1330 struct tcp_sock *newtp;
1331 struct sock *newsk;
1332 #ifdef CONFIG_TCP_MD5SIG
1333 struct tcp_md5sig_key *key;
1334 #endif
1335
1336 if (sk_acceptq_is_full(sk))
1337 goto exit_overflow;
1338
1339 if (!dst && (dst = inet_csk_route_req(sk, req)) == NULL)
1340 goto exit;
1341
1342 newsk = tcp_create_openreq_child(sk, req, skb);
1343 if (!newsk)
1344 goto exit;
1345
1346 newsk->sk_gso_type = SKB_GSO_TCPV4;
1347 sk_setup_caps(newsk, dst);
1348
1349 newtp = tcp_sk(newsk);
1350 newinet = inet_sk(newsk);
1351 ireq = inet_rsk(req);
1352 newinet->daddr = ireq->rmt_addr;
1353 newinet->rcv_saddr = ireq->loc_addr;
1354 newinet->saddr = ireq->loc_addr;
1355 newinet->opt = ireq->opt;
1356 ireq->opt = NULL;
1357 newinet->mc_index = inet_iif(skb);
1358 newinet->mc_ttl = ip_hdr(skb)->ttl;
1359 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1360 if (newinet->opt)
1361 inet_csk(newsk)->icsk_ext_hdr_len = newinet->opt->optlen;
1362 newinet->id = newtp->write_seq ^ jiffies;
1363
1364 tcp_mtup_init(newsk);
1365 tcp_sync_mss(newsk, dst_mtu(dst));
1366 newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
1367 if (tcp_sk(sk)->rx_opt.user_mss &&
1368 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1369 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1370
1371 tcp_initialize_rcv_mss(newsk);
1372
1373 #ifdef CONFIG_TCP_MD5SIG
1374 /* Copy over the MD5 key from the original socket */
1375 if ((key = tcp_v4_md5_do_lookup(sk, newinet->daddr)) != NULL) {
1376 /*
1377 * We're using one, so create a matching key
1378 * on the newsk structure. If we fail to get
1379 * memory, then we end up not copying the key
1380 * across. Shucks.
1381 */
1382 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1383 if (newkey != NULL)
1384 tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
1385 newkey, key->keylen);
1386 newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
1387 }
1388 #endif
1389
1390 __inet_hash_nolisten(newsk);
1391 __inet_inherit_port(sk, newsk);
1392
1393 return newsk;
1394
1395 exit_overflow:
1396 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1397 exit:
1398 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1399 dst_release(dst);
1400 return NULL;
1401 }
1402
1403 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1404 {
1405 struct tcphdr *th = tcp_hdr(skb);
1406 const struct iphdr *iph = ip_hdr(skb);
1407 struct sock *nsk;
1408 struct request_sock **prev;
1409 /* Find possible connection requests. */
1410 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1411 iph->saddr, iph->daddr);
1412 if (req)
1413 return tcp_check_req(sk, skb, req, prev);
1414
1415 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1416 th->source, iph->daddr, th->dest, inet_iif(skb));
1417
1418 if (nsk) {
1419 if (nsk->sk_state != TCP_TIME_WAIT) {
1420 bh_lock_sock(nsk);
1421 return nsk;
1422 }
1423 inet_twsk_put(inet_twsk(nsk));
1424 return NULL;
1425 }
1426
1427 #ifdef CONFIG_SYN_COOKIES
1428 if (!th->rst && !th->syn && th->ack)
1429 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1430 #endif
1431 return sk;
1432 }
1433
1434 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1435 {
1436 const struct iphdr *iph = ip_hdr(skb);
1437
1438 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1439 if (!tcp_v4_check(skb->len, iph->saddr,
1440 iph->daddr, skb->csum)) {
1441 skb->ip_summed = CHECKSUM_UNNECESSARY;
1442 return 0;
1443 }
1444 }
1445
1446 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1447 skb->len, IPPROTO_TCP, 0);
1448
1449 if (skb->len <= 76) {
1450 return __skb_checksum_complete(skb);
1451 }
1452 return 0;
1453 }
1454
1455
1456 /* The socket must have it's spinlock held when we get
1457 * here.
1458 *
1459 * We have a potential double-lock case here, so even when
1460 * doing backlog processing we use the BH locking scheme.
1461 * This is because we cannot sleep with the original spinlock
1462 * held.
1463 */
1464 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1465 {
1466 struct sock *rsk;
1467 #ifdef CONFIG_TCP_MD5SIG
1468 /*
1469 * We really want to reject the packet as early as possible
1470 * if:
1471 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1472 * o There is an MD5 option and we're not expecting one
1473 */
1474 if (tcp_v4_inbound_md5_hash(sk, skb))
1475 goto discard;
1476 #endif
1477
1478 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1479 TCP_CHECK_TIMER(sk);
1480 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1481 rsk = sk;
1482 goto reset;
1483 }
1484 TCP_CHECK_TIMER(sk);
1485 return 0;
1486 }
1487
1488 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1489 goto csum_err;
1490
1491 if (sk->sk_state == TCP_LISTEN) {
1492 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1493 if (!nsk)
1494 goto discard;
1495
1496 if (nsk != sk) {
1497 if (tcp_child_process(sk, nsk, skb)) {
1498 rsk = nsk;
1499 goto reset;
1500 }
1501 return 0;
1502 }
1503 }
1504
1505 TCP_CHECK_TIMER(sk);
1506 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1507 rsk = sk;
1508 goto reset;
1509 }
1510 TCP_CHECK_TIMER(sk);
1511 return 0;
1512
1513 reset:
1514 tcp_v4_send_reset(rsk, skb);
1515 discard:
1516 kfree_skb(skb);
1517 /* Be careful here. If this function gets more complicated and
1518 * gcc suffers from register pressure on the x86, sk (in %ebx)
1519 * might be destroyed here. This current version compiles correctly,
1520 * but you have been warned.
1521 */
1522 return 0;
1523
1524 csum_err:
1525 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1526 goto discard;
1527 }
1528
1529 /*
1530 * From tcp_input.c
1531 */
1532
1533 int tcp_v4_rcv(struct sk_buff *skb)
1534 {
1535 const struct iphdr *iph;
1536 struct tcphdr *th;
1537 struct sock *sk;
1538 int ret;
1539 struct net *net = dev_net(skb->dev);
1540
1541 if (skb->pkt_type != PACKET_HOST)
1542 goto discard_it;
1543
1544 /* Count it even if it's bad */
1545 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1546
1547 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1548 goto discard_it;
1549
1550 th = tcp_hdr(skb);
1551
1552 if (th->doff < sizeof(struct tcphdr) / 4)
1553 goto bad_packet;
1554 if (!pskb_may_pull(skb, th->doff * 4))
1555 goto discard_it;
1556
1557 /* An explanation is required here, I think.
1558 * Packet length and doff are validated by header prediction,
1559 * provided case of th->doff==0 is eliminated.
1560 * So, we defer the checks. */
1561 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1562 goto bad_packet;
1563
1564 th = tcp_hdr(skb);
1565 iph = ip_hdr(skb);
1566 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1567 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1568 skb->len - th->doff * 4);
1569 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1570 TCP_SKB_CB(skb)->when = 0;
1571 TCP_SKB_CB(skb)->flags = iph->tos;
1572 TCP_SKB_CB(skb)->sacked = 0;
1573
1574 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1575 if (!sk)
1576 goto no_tcp_socket;
1577
1578 process:
1579 if (sk->sk_state == TCP_TIME_WAIT)
1580 goto do_time_wait;
1581
1582 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1583 goto discard_and_relse;
1584 nf_reset(skb);
1585
1586 if (sk_filter(sk, skb))
1587 goto discard_and_relse;
1588
1589 skb->dev = NULL;
1590
1591 bh_lock_sock_nested(sk);
1592 ret = 0;
1593 if (!sock_owned_by_user(sk)) {
1594 #ifdef CONFIG_NET_DMA
1595 struct tcp_sock *tp = tcp_sk(sk);
1596 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1597 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1598 if (tp->ucopy.dma_chan)
1599 ret = tcp_v4_do_rcv(sk, skb);
1600 else
1601 #endif
1602 {
1603 if (!tcp_prequeue(sk, skb))
1604 ret = tcp_v4_do_rcv(sk, skb);
1605 }
1606 } else
1607 sk_add_backlog(sk, skb);
1608 bh_unlock_sock(sk);
1609
1610 sock_put(sk);
1611
1612 return ret;
1613
1614 no_tcp_socket:
1615 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1616 goto discard_it;
1617
1618 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1619 bad_packet:
1620 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1621 } else {
1622 tcp_v4_send_reset(NULL, skb);
1623 }
1624
1625 discard_it:
1626 /* Discard frame. */
1627 kfree_skb(skb);
1628 return 0;
1629
1630 discard_and_relse:
1631 sock_put(sk);
1632 goto discard_it;
1633
1634 do_time_wait:
1635 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1636 inet_twsk_put(inet_twsk(sk));
1637 goto discard_it;
1638 }
1639
1640 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1641 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1642 inet_twsk_put(inet_twsk(sk));
1643 goto discard_it;
1644 }
1645 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1646 case TCP_TW_SYN: {
1647 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1648 &tcp_hashinfo,
1649 iph->daddr, th->dest,
1650 inet_iif(skb));
1651 if (sk2) {
1652 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1653 inet_twsk_put(inet_twsk(sk));
1654 sk = sk2;
1655 goto process;
1656 }
1657 /* Fall through to ACK */
1658 }
1659 case TCP_TW_ACK:
1660 tcp_v4_timewait_ack(sk, skb);
1661 break;
1662 case TCP_TW_RST:
1663 goto no_tcp_socket;
1664 case TCP_TW_SUCCESS:;
1665 }
1666 goto discard_it;
1667 }
1668
1669 /* VJ's idea. Save last timestamp seen from this destination
1670 * and hold it at least for normal timewait interval to use for duplicate
1671 * segment detection in subsequent connections, before they enter synchronized
1672 * state.
1673 */
1674
1675 int tcp_v4_remember_stamp(struct sock *sk)
1676 {
1677 struct inet_sock *inet = inet_sk(sk);
1678 struct tcp_sock *tp = tcp_sk(sk);
1679 struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
1680 struct inet_peer *peer = NULL;
1681 int release_it = 0;
1682
1683 if (!rt || rt->rt_dst != inet->daddr) {
1684 peer = inet_getpeer(inet->daddr, 1);
1685 release_it = 1;
1686 } else {
1687 if (!rt->peer)
1688 rt_bind_peer(rt, 1);
1689 peer = rt->peer;
1690 }
1691
1692 if (peer) {
1693 if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
1694 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1695 peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
1696 peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
1697 peer->tcp_ts = tp->rx_opt.ts_recent;
1698 }
1699 if (release_it)
1700 inet_putpeer(peer);
1701 return 1;
1702 }
1703
1704 return 0;
1705 }
1706
1707 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw)
1708 {
1709 struct inet_peer *peer = inet_getpeer(tw->tw_daddr, 1);
1710
1711 if (peer) {
1712 const struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
1713
1714 if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 ||
1715 (peer->tcp_ts_stamp + TCP_PAWS_MSL < get_seconds() &&
1716 peer->tcp_ts_stamp <= tcptw->tw_ts_recent_stamp)) {
1717 peer->tcp_ts_stamp = tcptw->tw_ts_recent_stamp;
1718 peer->tcp_ts = tcptw->tw_ts_recent;
1719 }
1720 inet_putpeer(peer);
1721 return 1;
1722 }
1723
1724 return 0;
1725 }
1726
1727 struct inet_connection_sock_af_ops ipv4_specific = {
1728 .queue_xmit = ip_queue_xmit,
1729 .send_check = tcp_v4_send_check,
1730 .rebuild_header = inet_sk_rebuild_header,
1731 .conn_request = tcp_v4_conn_request,
1732 .syn_recv_sock = tcp_v4_syn_recv_sock,
1733 .remember_stamp = tcp_v4_remember_stamp,
1734 .net_header_len = sizeof(struct iphdr),
1735 .setsockopt = ip_setsockopt,
1736 .getsockopt = ip_getsockopt,
1737 .addr2sockaddr = inet_csk_addr2sockaddr,
1738 .sockaddr_len = sizeof(struct sockaddr_in),
1739 .bind_conflict = inet_csk_bind_conflict,
1740 #ifdef CONFIG_COMPAT
1741 .compat_setsockopt = compat_ip_setsockopt,
1742 .compat_getsockopt = compat_ip_getsockopt,
1743 #endif
1744 };
1745
1746 #ifdef CONFIG_TCP_MD5SIG
1747 static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1748 .md5_lookup = tcp_v4_md5_lookup,
1749 .calc_md5_hash = tcp_v4_md5_hash_skb,
1750 .md5_add = tcp_v4_md5_add_func,
1751 .md5_parse = tcp_v4_parse_md5_keys,
1752 };
1753 #endif
1754
1755 /* NOTE: A lot of things set to zero explicitly by call to
1756 * sk_alloc() so need not be done here.
1757 */
1758 static int tcp_v4_init_sock(struct sock *sk)
1759 {
1760 struct inet_connection_sock *icsk = inet_csk(sk);
1761 struct tcp_sock *tp = tcp_sk(sk);
1762
1763 skb_queue_head_init(&tp->out_of_order_queue);
1764 tcp_init_xmit_timers(sk);
1765 tcp_prequeue_init(tp);
1766
1767 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1768 tp->mdev = TCP_TIMEOUT_INIT;
1769
1770 /* So many TCP implementations out there (incorrectly) count the
1771 * initial SYN frame in their delayed-ACK and congestion control
1772 * algorithms that we must have the following bandaid to talk
1773 * efficiently to them. -DaveM
1774 */
1775 tp->snd_cwnd = 2;
1776
1777 /* See draft-stevens-tcpca-spec-01 for discussion of the
1778 * initialization of these values.
1779 */
1780 tp->snd_ssthresh = 0x7fffffff; /* Infinity */
1781 tp->snd_cwnd_clamp = ~0;
1782 tp->mss_cache = 536;
1783
1784 tp->reordering = sysctl_tcp_reordering;
1785 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1786
1787 sk->sk_state = TCP_CLOSE;
1788
1789 sk->sk_write_space = sk_stream_write_space;
1790 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1791
1792 icsk->icsk_af_ops = &ipv4_specific;
1793 icsk->icsk_sync_mss = tcp_sync_mss;
1794 #ifdef CONFIG_TCP_MD5SIG
1795 tp->af_specific = &tcp_sock_ipv4_specific;
1796 #endif
1797
1798 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1799 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1800
1801 local_bh_disable();
1802 percpu_counter_inc(&tcp_sockets_allocated);
1803 local_bh_enable();
1804
1805 return 0;
1806 }
1807
1808 void tcp_v4_destroy_sock(struct sock *sk)
1809 {
1810 struct tcp_sock *tp = tcp_sk(sk);
1811
1812 tcp_clear_xmit_timers(sk);
1813
1814 tcp_cleanup_congestion_control(sk);
1815
1816 /* Cleanup up the write buffer. */
1817 tcp_write_queue_purge(sk);
1818
1819 /* Cleans up our, hopefully empty, out_of_order_queue. */
1820 __skb_queue_purge(&tp->out_of_order_queue);
1821
1822 #ifdef CONFIG_TCP_MD5SIG
1823 /* Clean up the MD5 key list, if any */
1824 if (tp->md5sig_info) {
1825 tcp_v4_clear_md5_list(sk);
1826 kfree(tp->md5sig_info);
1827 tp->md5sig_info = NULL;
1828 }
1829 #endif
1830
1831 #ifdef CONFIG_NET_DMA
1832 /* Cleans up our sk_async_wait_queue */
1833 __skb_queue_purge(&sk->sk_async_wait_queue);
1834 #endif
1835
1836 /* Clean prequeue, it must be empty really */
1837 __skb_queue_purge(&tp->ucopy.prequeue);
1838
1839 /* Clean up a referenced TCP bind bucket. */
1840 if (inet_csk(sk)->icsk_bind_hash)
1841 inet_put_port(sk);
1842
1843 /*
1844 * If sendmsg cached page exists, toss it.
1845 */
1846 if (sk->sk_sndmsg_page) {
1847 __free_page(sk->sk_sndmsg_page);
1848 sk->sk_sndmsg_page = NULL;
1849 }
1850
1851 percpu_counter_dec(&tcp_sockets_allocated);
1852 }
1853
1854 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1855
1856 #ifdef CONFIG_PROC_FS
1857 /* Proc filesystem TCP sock list dumping. */
1858
1859 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
1860 {
1861 return hlist_nulls_empty(head) ? NULL :
1862 list_entry(head->first, struct inet_timewait_sock, tw_node);
1863 }
1864
1865 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1866 {
1867 return !is_a_nulls(tw->tw_node.next) ?
1868 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1869 }
1870
1871 static void *listening_get_next(struct seq_file *seq, void *cur)
1872 {
1873 struct inet_connection_sock *icsk;
1874 struct hlist_nulls_node *node;
1875 struct sock *sk = cur;
1876 struct inet_listen_hashbucket *ilb;
1877 struct tcp_iter_state *st = seq->private;
1878 struct net *net = seq_file_net(seq);
1879
1880 if (!sk) {
1881 st->bucket = 0;
1882 ilb = &tcp_hashinfo.listening_hash[0];
1883 spin_lock_bh(&ilb->lock);
1884 sk = sk_nulls_head(&ilb->head);
1885 goto get_sk;
1886 }
1887 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1888 ++st->num;
1889
1890 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1891 struct request_sock *req = cur;
1892
1893 icsk = inet_csk(st->syn_wait_sk);
1894 req = req->dl_next;
1895 while (1) {
1896 while (req) {
1897 if (req->rsk_ops->family == st->family) {
1898 cur = req;
1899 goto out;
1900 }
1901 req = req->dl_next;
1902 }
1903 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1904 break;
1905 get_req:
1906 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1907 }
1908 sk = sk_next(st->syn_wait_sk);
1909 st->state = TCP_SEQ_STATE_LISTENING;
1910 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1911 } else {
1912 icsk = inet_csk(sk);
1913 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1914 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1915 goto start_req;
1916 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1917 sk = sk_next(sk);
1918 }
1919 get_sk:
1920 sk_nulls_for_each_from(sk, node) {
1921 if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) {
1922 cur = sk;
1923 goto out;
1924 }
1925 icsk = inet_csk(sk);
1926 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1927 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1928 start_req:
1929 st->uid = sock_i_uid(sk);
1930 st->syn_wait_sk = sk;
1931 st->state = TCP_SEQ_STATE_OPENREQ;
1932 st->sbucket = 0;
1933 goto get_req;
1934 }
1935 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1936 }
1937 spin_unlock_bh(&ilb->lock);
1938 if (++st->bucket < INET_LHTABLE_SIZE) {
1939 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1940 spin_lock_bh(&ilb->lock);
1941 sk = sk_nulls_head(&ilb->head);
1942 goto get_sk;
1943 }
1944 cur = NULL;
1945 out:
1946 return cur;
1947 }
1948
1949 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1950 {
1951 void *rc = listening_get_next(seq, NULL);
1952
1953 while (rc && *pos) {
1954 rc = listening_get_next(seq, rc);
1955 --*pos;
1956 }
1957 return rc;
1958 }
1959
1960 static inline int empty_bucket(struct tcp_iter_state *st)
1961 {
1962 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
1963 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
1964 }
1965
1966 static void *established_get_first(struct seq_file *seq)
1967 {
1968 struct tcp_iter_state *st = seq->private;
1969 struct net *net = seq_file_net(seq);
1970 void *rc = NULL;
1971
1972 for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) {
1973 struct sock *sk;
1974 struct hlist_nulls_node *node;
1975 struct inet_timewait_sock *tw;
1976 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1977
1978 /* Lockless fast path for the common case of empty buckets */
1979 if (empty_bucket(st))
1980 continue;
1981
1982 spin_lock_bh(lock);
1983 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1984 if (sk->sk_family != st->family ||
1985 !net_eq(sock_net(sk), net)) {
1986 continue;
1987 }
1988 rc = sk;
1989 goto out;
1990 }
1991 st->state = TCP_SEQ_STATE_TIME_WAIT;
1992 inet_twsk_for_each(tw, node,
1993 &tcp_hashinfo.ehash[st->bucket].twchain) {
1994 if (tw->tw_family != st->family ||
1995 !net_eq(twsk_net(tw), net)) {
1996 continue;
1997 }
1998 rc = tw;
1999 goto out;
2000 }
2001 spin_unlock_bh(lock);
2002 st->state = TCP_SEQ_STATE_ESTABLISHED;
2003 }
2004 out:
2005 return rc;
2006 }
2007
2008 static void *established_get_next(struct seq_file *seq, void *cur)
2009 {
2010 struct sock *sk = cur;
2011 struct inet_timewait_sock *tw;
2012 struct hlist_nulls_node *node;
2013 struct tcp_iter_state *st = seq->private;
2014 struct net *net = seq_file_net(seq);
2015
2016 ++st->num;
2017
2018 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2019 tw = cur;
2020 tw = tw_next(tw);
2021 get_tw:
2022 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2023 tw = tw_next(tw);
2024 }
2025 if (tw) {
2026 cur = tw;
2027 goto out;
2028 }
2029 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2030 st->state = TCP_SEQ_STATE_ESTABLISHED;
2031
2032 /* Look for next non empty bucket */
2033 while (++st->bucket < tcp_hashinfo.ehash_size &&
2034 empty_bucket(st))
2035 ;
2036 if (st->bucket >= tcp_hashinfo.ehash_size)
2037 return NULL;
2038
2039 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2040 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2041 } else
2042 sk = sk_nulls_next(sk);
2043
2044 sk_nulls_for_each_from(sk, node) {
2045 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2046 goto found;
2047 }
2048
2049 st->state = TCP_SEQ_STATE_TIME_WAIT;
2050 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2051 goto get_tw;
2052 found:
2053 cur = sk;
2054 out:
2055 return cur;
2056 }
2057
2058 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2059 {
2060 void *rc = established_get_first(seq);
2061
2062 while (rc && pos) {
2063 rc = established_get_next(seq, rc);
2064 --pos;
2065 }
2066 return rc;
2067 }
2068
2069 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2070 {
2071 void *rc;
2072 struct tcp_iter_state *st = seq->private;
2073
2074 st->state = TCP_SEQ_STATE_LISTENING;
2075 rc = listening_get_idx(seq, &pos);
2076
2077 if (!rc) {
2078 st->state = TCP_SEQ_STATE_ESTABLISHED;
2079 rc = established_get_idx(seq, pos);
2080 }
2081
2082 return rc;
2083 }
2084
2085 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2086 {
2087 struct tcp_iter_state *st = seq->private;
2088 st->state = TCP_SEQ_STATE_LISTENING;
2089 st->num = 0;
2090 return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2091 }
2092
2093 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2094 {
2095 void *rc = NULL;
2096 struct tcp_iter_state *st;
2097
2098 if (v == SEQ_START_TOKEN) {
2099 rc = tcp_get_idx(seq, 0);
2100 goto out;
2101 }
2102 st = seq->private;
2103
2104 switch (st->state) {
2105 case TCP_SEQ_STATE_OPENREQ:
2106 case TCP_SEQ_STATE_LISTENING:
2107 rc = listening_get_next(seq, v);
2108 if (!rc) {
2109 st->state = TCP_SEQ_STATE_ESTABLISHED;
2110 rc = established_get_first(seq);
2111 }
2112 break;
2113 case TCP_SEQ_STATE_ESTABLISHED:
2114 case TCP_SEQ_STATE_TIME_WAIT:
2115 rc = established_get_next(seq, v);
2116 break;
2117 }
2118 out:
2119 ++*pos;
2120 return rc;
2121 }
2122
2123 static void tcp_seq_stop(struct seq_file *seq, void *v)
2124 {
2125 struct tcp_iter_state *st = seq->private;
2126
2127 switch (st->state) {
2128 case TCP_SEQ_STATE_OPENREQ:
2129 if (v) {
2130 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2131 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2132 }
2133 case TCP_SEQ_STATE_LISTENING:
2134 if (v != SEQ_START_TOKEN)
2135 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2136 break;
2137 case TCP_SEQ_STATE_TIME_WAIT:
2138 case TCP_SEQ_STATE_ESTABLISHED:
2139 if (v)
2140 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2141 break;
2142 }
2143 }
2144
2145 static int tcp_seq_open(struct inode *inode, struct file *file)
2146 {
2147 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2148 struct tcp_iter_state *s;
2149 int err;
2150
2151 err = seq_open_net(inode, file, &afinfo->seq_ops,
2152 sizeof(struct tcp_iter_state));
2153 if (err < 0)
2154 return err;
2155
2156 s = ((struct seq_file *)file->private_data)->private;
2157 s->family = afinfo->family;
2158 return 0;
2159 }
2160
2161 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2162 {
2163 int rc = 0;
2164 struct proc_dir_entry *p;
2165
2166 afinfo->seq_fops.open = tcp_seq_open;
2167 afinfo->seq_fops.read = seq_read;
2168 afinfo->seq_fops.llseek = seq_lseek;
2169 afinfo->seq_fops.release = seq_release_net;
2170
2171 afinfo->seq_ops.start = tcp_seq_start;
2172 afinfo->seq_ops.next = tcp_seq_next;
2173 afinfo->seq_ops.stop = tcp_seq_stop;
2174
2175 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2176 &afinfo->seq_fops, afinfo);
2177 if (!p)
2178 rc = -ENOMEM;
2179 return rc;
2180 }
2181
2182 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2183 {
2184 proc_net_remove(net, afinfo->name);
2185 }
2186
2187 static void get_openreq4(struct sock *sk, struct request_sock *req,
2188 struct seq_file *f, int i, int uid, int *len)
2189 {
2190 const struct inet_request_sock *ireq = inet_rsk(req);
2191 int ttd = req->expires - jiffies;
2192
2193 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2194 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
2195 i,
2196 ireq->loc_addr,
2197 ntohs(inet_sk(sk)->sport),
2198 ireq->rmt_addr,
2199 ntohs(ireq->rmt_port),
2200 TCP_SYN_RECV,
2201 0, 0, /* could print option size, but that is af dependent. */
2202 1, /* timers active (only the expire timer) */
2203 jiffies_to_clock_t(ttd),
2204 req->retrans,
2205 uid,
2206 0, /* non standard timer */
2207 0, /* open_requests have no inode */
2208 atomic_read(&sk->sk_refcnt),
2209 req,
2210 len);
2211 }
2212
2213 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2214 {
2215 int timer_active;
2216 unsigned long timer_expires;
2217 struct tcp_sock *tp = tcp_sk(sk);
2218 const struct inet_connection_sock *icsk = inet_csk(sk);
2219 struct inet_sock *inet = inet_sk(sk);
2220 __be32 dest = inet->daddr;
2221 __be32 src = inet->rcv_saddr;
2222 __u16 destp = ntohs(inet->dport);
2223 __u16 srcp = ntohs(inet->sport);
2224
2225 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2226 timer_active = 1;
2227 timer_expires = icsk->icsk_timeout;
2228 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2229 timer_active = 4;
2230 timer_expires = icsk->icsk_timeout;
2231 } else if (timer_pending(&sk->sk_timer)) {
2232 timer_active = 2;
2233 timer_expires = sk->sk_timer.expires;
2234 } else {
2235 timer_active = 0;
2236 timer_expires = jiffies;
2237 }
2238
2239 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2240 "%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
2241 i, src, srcp, dest, destp, sk->sk_state,
2242 tp->write_seq - tp->snd_una,
2243 sk->sk_state == TCP_LISTEN ? sk->sk_ack_backlog :
2244 (tp->rcv_nxt - tp->copied_seq),
2245 timer_active,
2246 jiffies_to_clock_t(timer_expires - jiffies),
2247 icsk->icsk_retransmits,
2248 sock_i_uid(sk),
2249 icsk->icsk_probes_out,
2250 sock_i_ino(sk),
2251 atomic_read(&sk->sk_refcnt), sk,
2252 jiffies_to_clock_t(icsk->icsk_rto),
2253 jiffies_to_clock_t(icsk->icsk_ack.ato),
2254 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2255 tp->snd_cwnd,
2256 tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh,
2257 len);
2258 }
2259
2260 static void get_timewait4_sock(struct inet_timewait_sock *tw,
2261 struct seq_file *f, int i, int *len)
2262 {
2263 __be32 dest, src;
2264 __u16 destp, srcp;
2265 int ttd = tw->tw_ttd - jiffies;
2266
2267 if (ttd < 0)
2268 ttd = 0;
2269
2270 dest = tw->tw_daddr;
2271 src = tw->tw_rcv_saddr;
2272 destp = ntohs(tw->tw_dport);
2273 srcp = ntohs(tw->tw_sport);
2274
2275 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2276 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
2277 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2278 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2279 atomic_read(&tw->tw_refcnt), tw, len);
2280 }
2281
2282 #define TMPSZ 150
2283
2284 static int tcp4_seq_show(struct seq_file *seq, void *v)
2285 {
2286 struct tcp_iter_state *st;
2287 int len;
2288
2289 if (v == SEQ_START_TOKEN) {
2290 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2291 " sl local_address rem_address st tx_queue "
2292 "rx_queue tr tm->when retrnsmt uid timeout "
2293 "inode");
2294 goto out;
2295 }
2296 st = seq->private;
2297
2298 switch (st->state) {
2299 case TCP_SEQ_STATE_LISTENING:
2300 case TCP_SEQ_STATE_ESTABLISHED:
2301 get_tcp4_sock(v, seq, st->num, &len);
2302 break;
2303 case TCP_SEQ_STATE_OPENREQ:
2304 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2305 break;
2306 case TCP_SEQ_STATE_TIME_WAIT:
2307 get_timewait4_sock(v, seq, st->num, &len);
2308 break;
2309 }
2310 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2311 out:
2312 return 0;
2313 }
2314
2315 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2316 .name = "tcp",
2317 .family = AF_INET,
2318 .seq_fops = {
2319 .owner = THIS_MODULE,
2320 },
2321 .seq_ops = {
2322 .show = tcp4_seq_show,
2323 },
2324 };
2325
2326 static int tcp4_proc_init_net(struct net *net)
2327 {
2328 return tcp_proc_register(net, &tcp4_seq_afinfo);
2329 }
2330
2331 static void tcp4_proc_exit_net(struct net *net)
2332 {
2333 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2334 }
2335
2336 static struct pernet_operations tcp4_net_ops = {
2337 .init = tcp4_proc_init_net,
2338 .exit = tcp4_proc_exit_net,
2339 };
2340
2341 int __init tcp4_proc_init(void)
2342 {
2343 return register_pernet_subsys(&tcp4_net_ops);
2344 }
2345
2346 void tcp4_proc_exit(void)
2347 {
2348 unregister_pernet_subsys(&tcp4_net_ops);
2349 }
2350 #endif /* CONFIG_PROC_FS */
2351
2352 struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2353 {
2354 struct iphdr *iph = ip_hdr(skb);
2355
2356 switch (skb->ip_summed) {
2357 case CHECKSUM_COMPLETE:
2358 if (!tcp_v4_check(skb->len, iph->saddr, iph->daddr,
2359 skb->csum)) {
2360 skb->ip_summed = CHECKSUM_UNNECESSARY;
2361 break;
2362 }
2363
2364 /* fall through */
2365 case CHECKSUM_NONE:
2366 NAPI_GRO_CB(skb)->flush = 1;
2367 return NULL;
2368 }
2369
2370 return tcp_gro_receive(head, skb);
2371 }
2372 EXPORT_SYMBOL(tcp4_gro_receive);
2373
2374 int tcp4_gro_complete(struct sk_buff *skb)
2375 {
2376 struct iphdr *iph = ip_hdr(skb);
2377 struct tcphdr *th = tcp_hdr(skb);
2378
2379 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
2380 iph->saddr, iph->daddr, 0);
2381 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
2382
2383 return tcp_gro_complete(skb);
2384 }
2385 EXPORT_SYMBOL(tcp4_gro_complete);
2386
2387 struct proto tcp_prot = {
2388 .name = "TCP",
2389 .owner = THIS_MODULE,
2390 .close = tcp_close,
2391 .connect = tcp_v4_connect,
2392 .disconnect = tcp_disconnect,
2393 .accept = inet_csk_accept,
2394 .ioctl = tcp_ioctl,
2395 .init = tcp_v4_init_sock,
2396 .destroy = tcp_v4_destroy_sock,
2397 .shutdown = tcp_shutdown,
2398 .setsockopt = tcp_setsockopt,
2399 .getsockopt = tcp_getsockopt,
2400 .recvmsg = tcp_recvmsg,
2401 .backlog_rcv = tcp_v4_do_rcv,
2402 .hash = inet_hash,
2403 .unhash = inet_unhash,
2404 .get_port = inet_csk_get_port,
2405 .enter_memory_pressure = tcp_enter_memory_pressure,
2406 .sockets_allocated = &tcp_sockets_allocated,
2407 .orphan_count = &tcp_orphan_count,
2408 .memory_allocated = &tcp_memory_allocated,
2409 .memory_pressure = &tcp_memory_pressure,
2410 .sysctl_mem = sysctl_tcp_mem,
2411 .sysctl_wmem = sysctl_tcp_wmem,
2412 .sysctl_rmem = sysctl_tcp_rmem,
2413 .max_header = MAX_TCP_HEADER,
2414 .obj_size = sizeof(struct tcp_sock),
2415 .slab_flags = SLAB_DESTROY_BY_RCU,
2416 .twsk_prot = &tcp_timewait_sock_ops,
2417 .rsk_prot = &tcp_request_sock_ops,
2418 .h.hashinfo = &tcp_hashinfo,
2419 #ifdef CONFIG_COMPAT
2420 .compat_setsockopt = compat_tcp_setsockopt,
2421 .compat_getsockopt = compat_tcp_getsockopt,
2422 #endif
2423 };
2424
2425
2426 static int __net_init tcp_sk_init(struct net *net)
2427 {
2428 return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2429 PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2430 }
2431
2432 static void __net_exit tcp_sk_exit(struct net *net)
2433 {
2434 inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2435 inet_twsk_purge(net, &tcp_hashinfo, &tcp_death_row, AF_INET);
2436 }
2437
2438 static struct pernet_operations __net_initdata tcp_sk_ops = {
2439 .init = tcp_sk_init,
2440 .exit = tcp_sk_exit,
2441 };
2442
2443 void __init tcp_v4_init(void)
2444 {
2445 inet_hashinfo_init(&tcp_hashinfo);
2446 if (register_pernet_subsys(&tcp_sk_ops))
2447 panic("Failed to create the TCP control socket.\n");
2448 }
2449
2450 EXPORT_SYMBOL(ipv4_specific);
2451 EXPORT_SYMBOL(tcp_hashinfo);
2452 EXPORT_SYMBOL(tcp_prot);
2453 EXPORT_SYMBOL(tcp_v4_conn_request);
2454 EXPORT_SYMBOL(tcp_v4_connect);
2455 EXPORT_SYMBOL(tcp_v4_do_rcv);
2456 EXPORT_SYMBOL(tcp_v4_remember_stamp);
2457 EXPORT_SYMBOL(tcp_v4_send_check);
2458 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
2459
2460 #ifdef CONFIG_PROC_FS
2461 EXPORT_SYMBOL(tcp_proc_register);
2462 EXPORT_SYMBOL(tcp_proc_unregister);
2463 #endif
2464 EXPORT_SYMBOL(sysctl_tcp_low_latency);
2465
Linux kernel - Deliverables
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