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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#include <linux/slab.h>
64
65#include <net/net_namespace.h>
66#include <net/icmp.h>
67#include <net/inet_hashtables.h>
68#include <net/tcp.h>
69#include <net/transp_v6.h>
70#include <net/ipv6.h>
71#include <net/inet_common.h>
72#include <net/timewait_sock.h>
73#include <net/xfrm.h>
74#include <net/netdma.h>
75#include <net/secure_seq.h>
76
77#include <linux/inet.h>
78#include <linux/ipv6.h>
79#include <linux/stddef.h>
80#include <linux/proc_fs.h>
81#include <linux/seq_file.h>
82
83#include <linux/crypto.h>
84#include <linux/scatterlist.h>
85
86int sysctl_tcp_tw_reuse __read_mostly;
87int sysctl_tcp_low_latency __read_mostly;
88EXPORT_SYMBOL(sysctl_tcp_low_latency);
89
90
91#ifdef CONFIG_TCP_MD5SIG
92static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
93 __be32 addr);
94static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
95 __be32 daddr, __be32 saddr, struct tcphdr *th);
96#else
97static inline
98struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
99{
100 return NULL;
101}
102#endif
103
104struct inet_hashinfo tcp_hashinfo;
105EXPORT_SYMBOL(tcp_hashinfo);
106
107static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
108{
109 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
110 ip_hdr(skb)->saddr,
111 tcp_hdr(skb)->dest,
112 tcp_hdr(skb)->source);
113}
114
115int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
116{
117 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
118 struct tcp_sock *tp = tcp_sk(sk);
119
120 /* With PAWS, it is safe from the viewpoint
121 of data integrity. Even without PAWS it is safe provided sequence
122 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
123
124 Actually, the idea is close to VJ's one, only timestamp cache is
125 held not per host, but per port pair and TW bucket is used as state
126 holder.
127
128 If TW bucket has been already destroyed we fall back to VJ's scheme
129 and use initial timestamp retrieved from peer table.
130 */
131 if (tcptw->tw_ts_recent_stamp &&
132 (twp == NULL || (sysctl_tcp_tw_reuse &&
133 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
134 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
135 if (tp->write_seq == 0)
136 tp->write_seq = 1;
137 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
138 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
139 sock_hold(sktw);
140 return 1;
141 }
142
143 return 0;
144}
145EXPORT_SYMBOL_GPL(tcp_twsk_unique);
146
147/* This will initiate an outgoing connection. */
148int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
149{
150 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
151 struct inet_sock *inet = inet_sk(sk);
152 struct tcp_sock *tp = tcp_sk(sk);
153 __be16 orig_sport, orig_dport;
154 __be32 daddr, nexthop;
155 struct flowi4 *fl4;
156 struct rtable *rt;
157 int err;
158 struct ip_options_rcu *inet_opt;
159
160 if (addr_len < sizeof(struct sockaddr_in))
161 return -EINVAL;
162
163 if (usin->sin_family != AF_INET)
164 return -EAFNOSUPPORT;
165
166 nexthop = daddr = usin->sin_addr.s_addr;
167 inet_opt = rcu_dereference_protected(inet->inet_opt,
168 sock_owned_by_user(sk));
169 if (inet_opt && inet_opt->opt.srr) {
170 if (!daddr)
171 return -EINVAL;
172 nexthop = inet_opt->opt.faddr;
173 }
174
175 orig_sport = inet->inet_sport;
176 orig_dport = usin->sin_port;
177 fl4 = &inet->cork.fl.u.ip4;
178 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
179 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
180 IPPROTO_TCP,
181 orig_sport, orig_dport, sk, true);
182 if (IS_ERR(rt)) {
183 err = PTR_ERR(rt);
184 if (err == -ENETUNREACH)
185 IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
186 return err;
187 }
188
189 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
190 ip_rt_put(rt);
191 return -ENETUNREACH;
192 }
193
194 if (!inet_opt || !inet_opt->opt.srr)
195 daddr = fl4->daddr;
196
197 if (!inet->inet_saddr)
198 inet->inet_saddr = fl4->saddr;
199 inet->inet_rcv_saddr = inet->inet_saddr;
200
201 if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
202 /* Reset inherited state */
203 tp->rx_opt.ts_recent = 0;
204 tp->rx_opt.ts_recent_stamp = 0;
205 tp->write_seq = 0;
206 }
207
208 if (tcp_death_row.sysctl_tw_recycle &&
209 !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr) {
210 struct inet_peer *peer = rt_get_peer(rt, fl4->daddr);
211 /*
212 * VJ's idea. We save last timestamp seen from
213 * the destination in peer table, when entering state
214 * TIME-WAIT * and initialize rx_opt.ts_recent from it,
215 * when trying new connection.
216 */
217 if (peer) {
218 inet_peer_refcheck(peer);
219 if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
220 tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
221 tp->rx_opt.ts_recent = peer->tcp_ts;
222 }
223 }
224 }
225
226 inet->inet_dport = usin->sin_port;
227 inet->inet_daddr = daddr;
228
229 inet_csk(sk)->icsk_ext_hdr_len = 0;
230 if (inet_opt)
231 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
232
233 tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
234
235 /* Socket identity is still unknown (sport may be zero).
236 * However we set state to SYN-SENT and not releasing socket
237 * lock select source port, enter ourselves into the hash tables and
238 * complete initialization after this.
239 */
240 tcp_set_state(sk, TCP_SYN_SENT);
241 err = inet_hash_connect(&tcp_death_row, sk);
242 if (err)
243 goto failure;
244
245 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
246 inet->inet_sport, inet->inet_dport, sk);
247 if (IS_ERR(rt)) {
248 err = PTR_ERR(rt);
249 rt = NULL;
250 goto failure;
251 }
252 /* OK, now commit destination to socket. */
253 sk->sk_gso_type = SKB_GSO_TCPV4;
254 sk_setup_caps(sk, &rt->dst);
255
256 if (!tp->write_seq)
257 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
258 inet->inet_daddr,
259 inet->inet_sport,
260 usin->sin_port);
261
262 inet->inet_id = tp->write_seq ^ jiffies;
263
264 err = tcp_connect(sk);
265 rt = NULL;
266 if (err)
267 goto failure;
268
269 return 0;
270
271failure:
272 /*
273 * This unhashes the socket and releases the local port,
274 * if necessary.
275 */
276 tcp_set_state(sk, TCP_CLOSE);
277 ip_rt_put(rt);
278 sk->sk_route_caps = 0;
279 inet->inet_dport = 0;
280 return err;
281}
282EXPORT_SYMBOL(tcp_v4_connect);
283
284/*
285 * This routine does path mtu discovery as defined in RFC1191.
286 */
287static void do_pmtu_discovery(struct sock *sk, const struct iphdr *iph, u32 mtu)
288{
289 struct dst_entry *dst;
290 struct inet_sock *inet = inet_sk(sk);
291
292 /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
293 * send out by Linux are always <576bytes so they should go through
294 * unfragmented).
295 */
296 if (sk->sk_state == TCP_LISTEN)
297 return;
298
299 /* We don't check in the destentry if pmtu discovery is forbidden
300 * on this route. We just assume that no packet_to_big packets
301 * are send back when pmtu discovery is not active.
302 * There is a small race when the user changes this flag in the
303 * route, but I think that's acceptable.
304 */
305 if ((dst = __sk_dst_check(sk, 0)) == NULL)
306 return;
307
308 dst->ops->update_pmtu(dst, mtu);
309
310 /* Something is about to be wrong... Remember soft error
311 * for the case, if this connection will not able to recover.
312 */
313 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
314 sk->sk_err_soft = EMSGSIZE;
315
316 mtu = dst_mtu(dst);
317
318 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
319 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
320 tcp_sync_mss(sk, mtu);
321
322 /* Resend the TCP packet because it's
323 * clear that the old packet has been
324 * dropped. This is the new "fast" path mtu
325 * discovery.
326 */
327 tcp_simple_retransmit(sk);
328 } /* else let the usual retransmit timer handle it */
329}
330
331/*
332 * This routine is called by the ICMP module when it gets some
333 * sort of error condition. If err < 0 then the socket should
334 * be closed and the error returned to the user. If err > 0
335 * it's just the icmp type << 8 | icmp code. After adjustment
336 * header points to the first 8 bytes of the tcp header. We need
337 * to find the appropriate port.
338 *
339 * The locking strategy used here is very "optimistic". When
340 * someone else accesses the socket the ICMP is just dropped
341 * and for some paths there is no check at all.
342 * A more general error queue to queue errors for later handling
343 * is probably better.
344 *
345 */
346
347void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
348{
349 const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
350 struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
351 struct inet_connection_sock *icsk;
352 struct tcp_sock *tp;
353 struct inet_sock *inet;
354 const int type = icmp_hdr(icmp_skb)->type;
355 const int code = icmp_hdr(icmp_skb)->code;
356 struct sock *sk;
357 struct sk_buff *skb;
358 __u32 seq;
359 __u32 remaining;
360 int err;
361 struct net *net = dev_net(icmp_skb->dev);
362
363 if (icmp_skb->len < (iph->ihl << 2) + 8) {
364 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
365 return;
366 }
367
368 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
369 iph->saddr, th->source, inet_iif(icmp_skb));
370 if (!sk) {
371 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
372 return;
373 }
374 if (sk->sk_state == TCP_TIME_WAIT) {
375 inet_twsk_put(inet_twsk(sk));
376 return;
377 }
378
379 bh_lock_sock(sk);
380 /* If too many ICMPs get dropped on busy
381 * servers this needs to be solved differently.
382 */
383 if (sock_owned_by_user(sk))
384 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
385
386 if (sk->sk_state == TCP_CLOSE)
387 goto out;
388
389 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
390 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
391 goto out;
392 }
393
394 icsk = inet_csk(sk);
395 tp = tcp_sk(sk);
396 seq = ntohl(th->seq);
397 if (sk->sk_state != TCP_LISTEN &&
398 !between(seq, tp->snd_una, tp->snd_nxt)) {
399 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
400 goto out;
401 }
402
403 switch (type) {
404 case ICMP_SOURCE_QUENCH:
405 /* Just silently ignore these. */
406 goto out;
407 case ICMP_PARAMETERPROB:
408 err = EPROTO;
409 break;
410 case ICMP_DEST_UNREACH:
411 if (code > NR_ICMP_UNREACH)
412 goto out;
413
414 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
415 if (!sock_owned_by_user(sk))
416 do_pmtu_discovery(sk, iph, info);
417 goto out;
418 }
419
420 err = icmp_err_convert[code].errno;
421 /* check if icmp_skb allows revert of backoff
422 * (see draft-zimmermann-tcp-lcd) */
423 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
424 break;
425 if (seq != tp->snd_una || !icsk->icsk_retransmits ||
426 !icsk->icsk_backoff)
427 break;
428
429 if (sock_owned_by_user(sk))
430 break;
431
432 icsk->icsk_backoff--;
433 inet_csk(sk)->icsk_rto = (tp->srtt ? __tcp_set_rto(tp) :
434 TCP_TIMEOUT_INIT) << icsk->icsk_backoff;
435 tcp_bound_rto(sk);
436
437 skb = tcp_write_queue_head(sk);
438 BUG_ON(!skb);
439
440 remaining = icsk->icsk_rto - min(icsk->icsk_rto,
441 tcp_time_stamp - TCP_SKB_CB(skb)->when);
442
443 if (remaining) {
444 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
445 remaining, TCP_RTO_MAX);
446 } else {
447 /* RTO revert clocked out retransmission.
448 * Will retransmit now */
449 tcp_retransmit_timer(sk);
450 }
451
452 break;
453 case ICMP_TIME_EXCEEDED:
454 err = EHOSTUNREACH;
455 break;
456 default:
457 goto out;
458 }
459
460 switch (sk->sk_state) {
461 struct request_sock *req, **prev;
462 case TCP_LISTEN:
463 if (sock_owned_by_user(sk))
464 goto out;
465
466 req = inet_csk_search_req(sk, &prev, th->dest,
467 iph->daddr, iph->saddr);
468 if (!req)
469 goto out;
470
471 /* ICMPs are not backlogged, hence we cannot get
472 an established socket here.
473 */
474 WARN_ON(req->sk);
475
476 if (seq != tcp_rsk(req)->snt_isn) {
477 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
478 goto out;
479 }
480
481 /*
482 * Still in SYN_RECV, just remove it silently.
483 * There is no good way to pass the error to the newly
484 * created socket, and POSIX does not want network
485 * errors returned from accept().
486 */
487 inet_csk_reqsk_queue_drop(sk, req, prev);
488 goto out;
489
490 case TCP_SYN_SENT:
491 case TCP_SYN_RECV: /* Cannot happen.
492 It can f.e. if SYNs crossed.
493 */
494 if (!sock_owned_by_user(sk)) {
495 sk->sk_err = err;
496
497 sk->sk_error_report(sk);
498
499 tcp_done(sk);
500 } else {
501 sk->sk_err_soft = err;
502 }
503 goto out;
504 }
505
506 /* If we've already connected we will keep trying
507 * until we time out, or the user gives up.
508 *
509 * rfc1122 4.2.3.9 allows to consider as hard errors
510 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
511 * but it is obsoleted by pmtu discovery).
512 *
513 * Note, that in modern internet, where routing is unreliable
514 * and in each dark corner broken firewalls sit, sending random
515 * errors ordered by their masters even this two messages finally lose
516 * their original sense (even Linux sends invalid PORT_UNREACHs)
517 *
518 * Now we are in compliance with RFCs.
519 * --ANK (980905)
520 */
521
522 inet = inet_sk(sk);
523 if (!sock_owned_by_user(sk) && inet->recverr) {
524 sk->sk_err = err;
525 sk->sk_error_report(sk);
526 } else { /* Only an error on timeout */
527 sk->sk_err_soft = err;
528 }
529
530out:
531 bh_unlock_sock(sk);
532 sock_put(sk);
533}
534
535static void __tcp_v4_send_check(struct sk_buff *skb,
536 __be32 saddr, __be32 daddr)
537{
538 struct tcphdr *th = tcp_hdr(skb);
539
540 if (skb->ip_summed == CHECKSUM_PARTIAL) {
541 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
542 skb->csum_start = skb_transport_header(skb) - skb->head;
543 skb->csum_offset = offsetof(struct tcphdr, check);
544 } else {
545 th->check = tcp_v4_check(skb->len, saddr, daddr,
546 csum_partial(th,
547 th->doff << 2,
548 skb->csum));
549 }
550}
551
552/* This routine computes an IPv4 TCP checksum. */
553void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
554{
555 struct inet_sock *inet = inet_sk(sk);
556
557 __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
558}
559EXPORT_SYMBOL(tcp_v4_send_check);
560
561int tcp_v4_gso_send_check(struct sk_buff *skb)
562{
563 const struct iphdr *iph;
564 struct tcphdr *th;
565
566 if (!pskb_may_pull(skb, sizeof(*th)))
567 return -EINVAL;
568
569 iph = ip_hdr(skb);
570 th = tcp_hdr(skb);
571
572 th->check = 0;
573 skb->ip_summed = CHECKSUM_PARTIAL;
574 __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
575 return 0;
576}
577
578/*
579 * This routine will send an RST to the other tcp.
580 *
581 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
582 * for reset.
583 * Answer: if a packet caused RST, it is not for a socket
584 * existing in our system, if it is matched to a socket,
585 * it is just duplicate segment or bug in other side's TCP.
586 * So that we build reply only basing on parameters
587 * arrived with segment.
588 * Exception: precedence violation. We do not implement it in any case.
589 */
590
591static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
592{
593 struct tcphdr *th = tcp_hdr(skb);
594 struct {
595 struct tcphdr th;
596#ifdef CONFIG_TCP_MD5SIG
597 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
598#endif
599 } rep;
600 struct ip_reply_arg arg;
601#ifdef CONFIG_TCP_MD5SIG
602 struct tcp_md5sig_key *key;
603#endif
604 struct net *net;
605
606 /* Never send a reset in response to a reset. */
607 if (th->rst)
608 return;
609
610 if (skb_rtable(skb)->rt_type != RTN_LOCAL)
611 return;
612
613 /* Swap the send and the receive. */
614 memset(&rep, 0, sizeof(rep));
615 rep.th.dest = th->source;
616 rep.th.source = th->dest;
617 rep.th.doff = sizeof(struct tcphdr) / 4;
618 rep.th.rst = 1;
619
620 if (th->ack) {
621 rep.th.seq = th->ack_seq;
622 } else {
623 rep.th.ack = 1;
624 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
625 skb->len - (th->doff << 2));
626 }
627
628 memset(&arg, 0, sizeof(arg));
629 arg.iov[0].iov_base = (unsigned char *)&rep;
630 arg.iov[0].iov_len = sizeof(rep.th);
631
632#ifdef CONFIG_TCP_MD5SIG
633 key = sk ? tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr) : NULL;
634 if (key) {
635 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
636 (TCPOPT_NOP << 16) |
637 (TCPOPT_MD5SIG << 8) |
638 TCPOLEN_MD5SIG);
639 /* Update length and the length the header thinks exists */
640 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
641 rep.th.doff = arg.iov[0].iov_len / 4;
642
643 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
644 key, ip_hdr(skb)->saddr,
645 ip_hdr(skb)->daddr, &rep.th);
646 }
647#endif
648 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
649 ip_hdr(skb)->saddr, /* XXX */
650 arg.iov[0].iov_len, IPPROTO_TCP, 0);
651 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
652 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
653
654 net = dev_net(skb_dst(skb)->dev);
655 ip_send_reply(net->ipv4.tcp_sock, skb, ip_hdr(skb)->saddr,
656 &arg, arg.iov[0].iov_len);
657
658 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
659 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
660}
661
662/* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
663 outside socket context is ugly, certainly. What can I do?
664 */
665
666static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
667 u32 win, u32 ts, int oif,
668 struct tcp_md5sig_key *key,
669 int reply_flags)
670{
671 struct tcphdr *th = tcp_hdr(skb);
672 struct {
673 struct tcphdr th;
674 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
675#ifdef CONFIG_TCP_MD5SIG
676 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
677#endif
678 ];
679 } rep;
680 struct ip_reply_arg arg;
681 struct net *net = dev_net(skb_dst(skb)->dev);
682
683 memset(&rep.th, 0, sizeof(struct tcphdr));
684 memset(&arg, 0, sizeof(arg));
685
686 arg.iov[0].iov_base = (unsigned char *)&rep;
687 arg.iov[0].iov_len = sizeof(rep.th);
688 if (ts) {
689 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
690 (TCPOPT_TIMESTAMP << 8) |
691 TCPOLEN_TIMESTAMP);
692 rep.opt[1] = htonl(tcp_time_stamp);
693 rep.opt[2] = htonl(ts);
694 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
695 }
696
697 /* Swap the send and the receive. */
698 rep.th.dest = th->source;
699 rep.th.source = th->dest;
700 rep.th.doff = arg.iov[0].iov_len / 4;
701 rep.th.seq = htonl(seq);
702 rep.th.ack_seq = htonl(ack);
703 rep.th.ack = 1;
704 rep.th.window = htons(win);
705
706#ifdef CONFIG_TCP_MD5SIG
707 if (key) {
708 int offset = (ts) ? 3 : 0;
709
710 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
711 (TCPOPT_NOP << 16) |
712 (TCPOPT_MD5SIG << 8) |
713 TCPOLEN_MD5SIG);
714 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
715 rep.th.doff = arg.iov[0].iov_len/4;
716
717 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
718 key, ip_hdr(skb)->saddr,
719 ip_hdr(skb)->daddr, &rep.th);
720 }
721#endif
722 arg.flags = reply_flags;
723 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
724 ip_hdr(skb)->saddr, /* XXX */
725 arg.iov[0].iov_len, IPPROTO_TCP, 0);
726 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
727 if (oif)
728 arg.bound_dev_if = oif;
729
730 ip_send_reply(net->ipv4.tcp_sock, skb, ip_hdr(skb)->saddr,
731 &arg, arg.iov[0].iov_len);
732
733 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
734}
735
736static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
737{
738 struct inet_timewait_sock *tw = inet_twsk(sk);
739 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
740
741 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
742 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
743 tcptw->tw_ts_recent,
744 tw->tw_bound_dev_if,
745 tcp_twsk_md5_key(tcptw),
746 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0
747 );
748
749 inet_twsk_put(tw);
750}
751
752static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
753 struct request_sock *req)
754{
755 tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
756 tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
757 req->ts_recent,
758 0,
759 tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr),
760 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0);
761}
762
763/*
764 * Send a SYN-ACK after having received a SYN.
765 * This still operates on a request_sock only, not on a big
766 * socket.
767 */
768static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
769 struct request_sock *req,
770 struct request_values *rvp)
771{
772 const struct inet_request_sock *ireq = inet_rsk(req);
773 struct flowi4 fl4;
774 int err = -1;
775 struct sk_buff * skb;
776
777 /* First, grab a route. */
778 if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
779 return -1;
780
781 skb = tcp_make_synack(sk, dst, req, rvp);
782
783 if (skb) {
784 __tcp_v4_send_check(skb, ireq->loc_addr, ireq->rmt_addr);
785
786 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
787 ireq->rmt_addr,
788 ireq->opt);
789 err = net_xmit_eval(err);
790 }
791
792 dst_release(dst);
793 return err;
794}
795
796static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req,
797 struct request_values *rvp)
798{
799 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
800 return tcp_v4_send_synack(sk, NULL, req, rvp);
801}
802
803/*
804 * IPv4 request_sock destructor.
805 */
806static void tcp_v4_reqsk_destructor(struct request_sock *req)
807{
808 kfree(inet_rsk(req)->opt);
809}
810
811/*
812 * Return 1 if a syncookie should be sent
813 */
814int tcp_syn_flood_action(struct sock *sk,
815 const struct sk_buff *skb,
816 const char *proto)
817{
818 const char *msg = "Dropping request";
819 int want_cookie = 0;
820 struct listen_sock *lopt;
821
822
823
824#ifdef CONFIG_SYN_COOKIES
825 if (sysctl_tcp_syncookies) {
826 msg = "Sending cookies";
827 want_cookie = 1;
828 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDOCOOKIES);
829 } else
830#endif
831 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
832
833 lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
834 if (!lopt->synflood_warned) {
835 lopt->synflood_warned = 1;
836 pr_info("%s: Possible SYN flooding on port %d. %s. "
837 " Check SNMP counters.\n",
838 proto, ntohs(tcp_hdr(skb)->dest), msg);
839 }
840 return want_cookie;
841}
842EXPORT_SYMBOL(tcp_syn_flood_action);
843
844/*
845 * Save and compile IPv4 options into the request_sock if needed.
846 */
847static struct ip_options_rcu *tcp_v4_save_options(struct sock *sk,
848 struct sk_buff *skb)
849{
850 const struct ip_options *opt = &(IPCB(skb)->opt);
851 struct ip_options_rcu *dopt = NULL;
852
853 if (opt && opt->optlen) {
854 int opt_size = sizeof(*dopt) + opt->optlen;
855
856 dopt = kmalloc(opt_size, GFP_ATOMIC);
857 if (dopt) {
858 if (ip_options_echo(&dopt->opt, skb)) {
859 kfree(dopt);
860 dopt = NULL;
861 }
862 }
863 }
864 return dopt;
865}
866
867#ifdef CONFIG_TCP_MD5SIG
868/*
869 * RFC2385 MD5 checksumming requires a mapping of
870 * IP address->MD5 Key.
871 * We need to maintain these in the sk structure.
872 */
873
874/* Find the Key structure for an address. */
875static struct tcp_md5sig_key *
876 tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
877{
878 struct tcp_sock *tp = tcp_sk(sk);
879 int i;
880
881 if (!tp->md5sig_info || !tp->md5sig_info->entries4)
882 return NULL;
883 for (i = 0; i < tp->md5sig_info->entries4; i++) {
884 if (tp->md5sig_info->keys4[i].addr == addr)
885 return &tp->md5sig_info->keys4[i].base;
886 }
887 return NULL;
888}
889
890struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
891 struct sock *addr_sk)
892{
893 return tcp_v4_md5_do_lookup(sk, inet_sk(addr_sk)->inet_daddr);
894}
895EXPORT_SYMBOL(tcp_v4_md5_lookup);
896
897static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
898 struct request_sock *req)
899{
900 return tcp_v4_md5_do_lookup(sk, inet_rsk(req)->rmt_addr);
901}
902
903/* This can be called on a newly created socket, from other files */
904int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
905 u8 *newkey, u8 newkeylen)
906{
907 /* Add Key to the list */
908 struct tcp_md5sig_key *key;
909 struct tcp_sock *tp = tcp_sk(sk);
910 struct tcp4_md5sig_key *keys;
911
912 key = tcp_v4_md5_do_lookup(sk, addr);
913 if (key) {
914 /* Pre-existing entry - just update that one. */
915 kfree(key->key);
916 key->key = newkey;
917 key->keylen = newkeylen;
918 } else {
919 struct tcp_md5sig_info *md5sig;
920
921 if (!tp->md5sig_info) {
922 tp->md5sig_info = kzalloc(sizeof(*tp->md5sig_info),
923 GFP_ATOMIC);
924 if (!tp->md5sig_info) {
925 kfree(newkey);
926 return -ENOMEM;
927 }
928 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
929 }
930
931 md5sig = tp->md5sig_info;
932 if (md5sig->entries4 == 0 &&
933 tcp_alloc_md5sig_pool(sk) == NULL) {
934 kfree(newkey);
935 return -ENOMEM;
936 }
937
938 if (md5sig->alloced4 == md5sig->entries4) {
939 keys = kmalloc((sizeof(*keys) *
940 (md5sig->entries4 + 1)), GFP_ATOMIC);
941 if (!keys) {
942 kfree(newkey);
943 if (md5sig->entries4 == 0)
944 tcp_free_md5sig_pool();
945 return -ENOMEM;
946 }
947
948 if (md5sig->entries4)
949 memcpy(keys, md5sig->keys4,
950 sizeof(*keys) * md5sig->entries4);
951
952 /* Free old key list, and reference new one */
953 kfree(md5sig->keys4);
954 md5sig->keys4 = keys;
955 md5sig->alloced4++;
956 }
957 md5sig->entries4++;
958 md5sig->keys4[md5sig->entries4 - 1].addr = addr;
959 md5sig->keys4[md5sig->entries4 - 1].base.key = newkey;
960 md5sig->keys4[md5sig->entries4 - 1].base.keylen = newkeylen;
961 }
962 return 0;
963}
964EXPORT_SYMBOL(tcp_v4_md5_do_add);
965
966static int tcp_v4_md5_add_func(struct sock *sk, struct sock *addr_sk,
967 u8 *newkey, u8 newkeylen)
968{
969 return tcp_v4_md5_do_add(sk, inet_sk(addr_sk)->inet_daddr,
970 newkey, newkeylen);
971}
972
973int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
974{
975 struct tcp_sock *tp = tcp_sk(sk);
976 int i;
977
978 for (i = 0; i < tp->md5sig_info->entries4; i++) {
979 if (tp->md5sig_info->keys4[i].addr == addr) {
980 /* Free the key */
981 kfree(tp->md5sig_info->keys4[i].base.key);
982 tp->md5sig_info->entries4--;
983
984 if (tp->md5sig_info->entries4 == 0) {
985 kfree(tp->md5sig_info->keys4);
986 tp->md5sig_info->keys4 = NULL;
987 tp->md5sig_info->alloced4 = 0;
988 tcp_free_md5sig_pool();
989 } else if (tp->md5sig_info->entries4 != i) {
990 /* Need to do some manipulation */
991 memmove(&tp->md5sig_info->keys4[i],
992 &tp->md5sig_info->keys4[i+1],
993 (tp->md5sig_info->entries4 - i) *
994 sizeof(struct tcp4_md5sig_key));
995 }
996 return 0;
997 }
998 }
999 return -ENOENT;
1000}
1001EXPORT_SYMBOL(tcp_v4_md5_do_del);
1002
1003static void tcp_v4_clear_md5_list(struct sock *sk)
1004{
1005 struct tcp_sock *tp = tcp_sk(sk);
1006
1007 /* Free each key, then the set of key keys,
1008 * the crypto element, and then decrement our
1009 * hold on the last resort crypto.
1010 */
1011 if (tp->md5sig_info->entries4) {
1012 int i;
1013 for (i = 0; i < tp->md5sig_info->entries4; i++)
1014 kfree(tp->md5sig_info->keys4[i].base.key);
1015 tp->md5sig_info->entries4 = 0;
1016 tcp_free_md5sig_pool();
1017 }
1018 if (tp->md5sig_info->keys4) {
1019 kfree(tp->md5sig_info->keys4);
1020 tp->md5sig_info->keys4 = NULL;
1021 tp->md5sig_info->alloced4 = 0;
1022 }
1023}
1024
1025static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
1026 int optlen)
1027{
1028 struct tcp_md5sig cmd;
1029 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
1030 u8 *newkey;
1031
1032 if (optlen < sizeof(cmd))
1033 return -EINVAL;
1034
1035 if (copy_from_user(&cmd, optval, sizeof(cmd)))
1036 return -EFAULT;
1037
1038 if (sin->sin_family != AF_INET)
1039 return -EINVAL;
1040
1041 if (!cmd.tcpm_key || !cmd.tcpm_keylen) {
1042 if (!tcp_sk(sk)->md5sig_info)
1043 return -ENOENT;
1044 return tcp_v4_md5_do_del(sk, sin->sin_addr.s_addr);
1045 }
1046
1047 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1048 return -EINVAL;
1049
1050 if (!tcp_sk(sk)->md5sig_info) {
1051 struct tcp_sock *tp = tcp_sk(sk);
1052 struct tcp_md5sig_info *p;
1053
1054 p = kzalloc(sizeof(*p), sk->sk_allocation);
1055 if (!p)
1056 return -EINVAL;
1057
1058 tp->md5sig_info = p;
1059 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
1060 }
1061
1062 newkey = kmemdup(cmd.tcpm_key, cmd.tcpm_keylen, sk->sk_allocation);
1063 if (!newkey)
1064 return -ENOMEM;
1065 return tcp_v4_md5_do_add(sk, sin->sin_addr.s_addr,
1066 newkey, cmd.tcpm_keylen);
1067}
1068
1069static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1070 __be32 daddr, __be32 saddr, int nbytes)
1071{
1072 struct tcp4_pseudohdr *bp;
1073 struct scatterlist sg;
1074
1075 bp = &hp->md5_blk.ip4;
1076
1077 /*
1078 * 1. the TCP pseudo-header (in the order: source IP address,
1079 * destination IP address, zero-padded protocol number, and
1080 * segment length)
1081 */
1082 bp->saddr = saddr;
1083 bp->daddr = daddr;
1084 bp->pad = 0;
1085 bp->protocol = IPPROTO_TCP;
1086 bp->len = cpu_to_be16(nbytes);
1087
1088 sg_init_one(&sg, bp, sizeof(*bp));
1089 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1090}
1091
1092static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
1093 __be32 daddr, __be32 saddr, struct tcphdr *th)
1094{
1095 struct tcp_md5sig_pool *hp;
1096 struct hash_desc *desc;
1097
1098 hp = tcp_get_md5sig_pool();
1099 if (!hp)
1100 goto clear_hash_noput;
1101 desc = &hp->md5_desc;
1102
1103 if (crypto_hash_init(desc))
1104 goto clear_hash;
1105 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1106 goto clear_hash;
1107 if (tcp_md5_hash_header(hp, th))
1108 goto clear_hash;
1109 if (tcp_md5_hash_key(hp, key))
1110 goto clear_hash;
1111 if (crypto_hash_final(desc, md5_hash))
1112 goto clear_hash;
1113
1114 tcp_put_md5sig_pool();
1115 return 0;
1116
1117clear_hash:
1118 tcp_put_md5sig_pool();
1119clear_hash_noput:
1120 memset(md5_hash, 0, 16);
1121 return 1;
1122}
1123
1124int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1125 struct sock *sk, struct request_sock *req,
1126 struct sk_buff *skb)
1127{
1128 struct tcp_md5sig_pool *hp;
1129 struct hash_desc *desc;
1130 struct tcphdr *th = tcp_hdr(skb);
1131 __be32 saddr, daddr;
1132
1133 if (sk) {
1134 saddr = inet_sk(sk)->inet_saddr;
1135 daddr = inet_sk(sk)->inet_daddr;
1136 } else if (req) {
1137 saddr = inet_rsk(req)->loc_addr;
1138 daddr = inet_rsk(req)->rmt_addr;
1139 } else {
1140 const struct iphdr *iph = ip_hdr(skb);
1141 saddr = iph->saddr;
1142 daddr = iph->daddr;
1143 }
1144
1145 hp = tcp_get_md5sig_pool();
1146 if (!hp)
1147 goto clear_hash_noput;
1148 desc = &hp->md5_desc;
1149
1150 if (crypto_hash_init(desc))
1151 goto clear_hash;
1152
1153 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1154 goto clear_hash;
1155 if (tcp_md5_hash_header(hp, th))
1156 goto clear_hash;
1157 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1158 goto clear_hash;
1159 if (tcp_md5_hash_key(hp, key))
1160 goto clear_hash;
1161 if (crypto_hash_final(desc, md5_hash))
1162 goto clear_hash;
1163
1164 tcp_put_md5sig_pool();
1165 return 0;
1166
1167clear_hash:
1168 tcp_put_md5sig_pool();
1169clear_hash_noput:
1170 memset(md5_hash, 0, 16);
1171 return 1;
1172}
1173EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1174
1175static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
1176{
1177 /*
1178 * This gets called for each TCP segment that arrives
1179 * so we want to be efficient.
1180 * We have 3 drop cases:
1181 * o No MD5 hash and one expected.
1182 * o MD5 hash and we're not expecting one.
1183 * o MD5 hash and its wrong.
1184 */
1185 __u8 *hash_location = NULL;
1186 struct tcp_md5sig_key *hash_expected;
1187 const struct iphdr *iph = ip_hdr(skb);
1188 struct tcphdr *th = tcp_hdr(skb);
1189 int genhash;
1190 unsigned char newhash[16];
1191
1192 hash_expected = tcp_v4_md5_do_lookup(sk, iph->saddr);
1193 hash_location = tcp_parse_md5sig_option(th);
1194
1195 /* We've parsed the options - do we have a hash? */
1196 if (!hash_expected && !hash_location)
1197 return 0;
1198
1199 if (hash_expected && !hash_location) {
1200 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1201 return 1;
1202 }
1203
1204 if (!hash_expected && hash_location) {
1205 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1206 return 1;
1207 }
1208
1209 /* Okay, so this is hash_expected and hash_location -
1210 * so we need to calculate the checksum.
1211 */
1212 genhash = tcp_v4_md5_hash_skb(newhash,
1213 hash_expected,
1214 NULL, NULL, skb);
1215
1216 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1217 if (net_ratelimit()) {
1218 printk(KERN_INFO "MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1219 &iph->saddr, ntohs(th->source),
1220 &iph->daddr, ntohs(th->dest),
1221 genhash ? " tcp_v4_calc_md5_hash failed" : "");
1222 }
1223 return 1;
1224 }
1225 return 0;
1226}
1227
1228#endif
1229
1230struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1231 .family = PF_INET,
1232 .obj_size = sizeof(struct tcp_request_sock),
1233 .rtx_syn_ack = tcp_v4_rtx_synack,
1234 .send_ack = tcp_v4_reqsk_send_ack,
1235 .destructor = tcp_v4_reqsk_destructor,
1236 .send_reset = tcp_v4_send_reset,
1237 .syn_ack_timeout = tcp_syn_ack_timeout,
1238};
1239
1240#ifdef CONFIG_TCP_MD5SIG
1241static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1242 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1243 .calc_md5_hash = tcp_v4_md5_hash_skb,
1244};
1245#endif
1246
1247int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1248{
1249 struct tcp_extend_values tmp_ext;
1250 struct tcp_options_received tmp_opt;
1251 u8 *hash_location;
1252 struct request_sock *req;
1253 struct inet_request_sock *ireq;
1254 struct tcp_sock *tp = tcp_sk(sk);
1255 struct dst_entry *dst = NULL;
1256 __be32 saddr = ip_hdr(skb)->saddr;
1257 __be32 daddr = ip_hdr(skb)->daddr;
1258 __u32 isn = TCP_SKB_CB(skb)->when;
1259 int want_cookie = 0;
1260
1261 /* Never answer to SYNs send to broadcast or multicast */
1262 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1263 goto drop;
1264
1265 /* TW buckets are converted to open requests without
1266 * limitations, they conserve resources and peer is
1267 * evidently real one.
1268 */
1269 if (inet_csk_reqsk_queue_is_full(sk) && !isn) {
1270 want_cookie = tcp_syn_flood_action(sk, skb, "TCP");
1271 if (!want_cookie)
1272 goto drop;
1273 }
1274
1275 /* Accept backlog is full. If we have already queued enough
1276 * of warm entries in syn queue, drop request. It is better than
1277 * clogging syn queue with openreqs with exponentially increasing
1278 * timeout.
1279 */
1280 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
1281 goto drop;
1282
1283 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1284 if (!req)
1285 goto drop;
1286
1287#ifdef CONFIG_TCP_MD5SIG
1288 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1289#endif
1290
1291 tcp_clear_options(&tmp_opt);
1292 tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
1293 tmp_opt.user_mss = tp->rx_opt.user_mss;
1294 tcp_parse_options(skb, &tmp_opt, &hash_location, 0);
1295
1296 if (tmp_opt.cookie_plus > 0 &&
1297 tmp_opt.saw_tstamp &&
1298 !tp->rx_opt.cookie_out_never &&
1299 (sysctl_tcp_cookie_size > 0 ||
1300 (tp->cookie_values != NULL &&
1301 tp->cookie_values->cookie_desired > 0))) {
1302 u8 *c;
1303 u32 *mess = &tmp_ext.cookie_bakery[COOKIE_DIGEST_WORDS];
1304 int l = tmp_opt.cookie_plus - TCPOLEN_COOKIE_BASE;
1305
1306 if (tcp_cookie_generator(&tmp_ext.cookie_bakery[0]) != 0)
1307 goto drop_and_release;
1308
1309 /* Secret recipe starts with IP addresses */
1310 *mess++ ^= (__force u32)daddr;
1311 *mess++ ^= (__force u32)saddr;
1312
1313 /* plus variable length Initiator Cookie */
1314 c = (u8 *)mess;
1315 while (l-- > 0)
1316 *c++ ^= *hash_location++;
1317
1318 want_cookie = 0; /* not our kind of cookie */
1319 tmp_ext.cookie_out_never = 0; /* false */
1320 tmp_ext.cookie_plus = tmp_opt.cookie_plus;
1321 } else if (!tp->rx_opt.cookie_in_always) {
1322 /* redundant indications, but ensure initialization. */
1323 tmp_ext.cookie_out_never = 1; /* true */
1324 tmp_ext.cookie_plus = 0;
1325 } else {
1326 goto drop_and_release;
1327 }
1328 tmp_ext.cookie_in_always = tp->rx_opt.cookie_in_always;
1329
1330 if (want_cookie && !tmp_opt.saw_tstamp)
1331 tcp_clear_options(&tmp_opt);
1332
1333 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1334 tcp_openreq_init(req, &tmp_opt, skb);
1335
1336 ireq = inet_rsk(req);
1337 ireq->loc_addr = daddr;
1338 ireq->rmt_addr = saddr;
1339 ireq->no_srccheck = inet_sk(sk)->transparent;
1340 ireq->opt = tcp_v4_save_options(sk, skb);
1341
1342 if (security_inet_conn_request(sk, skb, req))
1343 goto drop_and_free;
1344
1345 if (!want_cookie || tmp_opt.tstamp_ok)
1346 TCP_ECN_create_request(req, tcp_hdr(skb));
1347
1348 if (want_cookie) {
1349 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1350 req->cookie_ts = tmp_opt.tstamp_ok;
1351 } else if (!isn) {
1352 struct inet_peer *peer = NULL;
1353 struct flowi4 fl4;
1354
1355 /* VJ's idea. We save last timestamp seen
1356 * from the destination in peer table, when entering
1357 * state TIME-WAIT, and check against it before
1358 * accepting new connection request.
1359 *
1360 * If "isn" is not zero, this request hit alive
1361 * timewait bucket, so that all the necessary checks
1362 * are made in the function processing timewait state.
1363 */
1364 if (tmp_opt.saw_tstamp &&
1365 tcp_death_row.sysctl_tw_recycle &&
1366 (dst = inet_csk_route_req(sk, &fl4, req)) != NULL &&
1367 fl4.daddr == saddr &&
1368 (peer = rt_get_peer((struct rtable *)dst, fl4.daddr)) != NULL) {
1369 inet_peer_refcheck(peer);
1370 if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
1371 (s32)(peer->tcp_ts - req->ts_recent) >
1372 TCP_PAWS_WINDOW) {
1373 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1374 goto drop_and_release;
1375 }
1376 }
1377 /* Kill the following clause, if you dislike this way. */
1378 else if (!sysctl_tcp_syncookies &&
1379 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1380 (sysctl_max_syn_backlog >> 2)) &&
1381 (!peer || !peer->tcp_ts_stamp) &&
1382 (!dst || !dst_metric(dst, RTAX_RTT))) {
1383 /* Without syncookies last quarter of
1384 * backlog is filled with destinations,
1385 * proven to be alive.
1386 * It means that we continue to communicate
1387 * to destinations, already remembered
1388 * to the moment of synflood.
1389 */
1390 LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI4/%u\n",
1391 &saddr, ntohs(tcp_hdr(skb)->source));
1392 goto drop_and_release;
1393 }
1394
1395 isn = tcp_v4_init_sequence(skb);
1396 }
1397 tcp_rsk(req)->snt_isn = isn;
1398 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1399
1400 if (tcp_v4_send_synack(sk, dst, req,
1401 (struct request_values *)&tmp_ext) ||
1402 want_cookie)
1403 goto drop_and_free;
1404
1405 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1406 return 0;
1407
1408drop_and_release:
1409 dst_release(dst);
1410drop_and_free:
1411 reqsk_free(req);
1412drop:
1413 return 0;
1414}
1415EXPORT_SYMBOL(tcp_v4_conn_request);
1416
1417
1418/*
1419 * The three way handshake has completed - we got a valid synack -
1420 * now create the new socket.
1421 */
1422struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1423 struct request_sock *req,
1424 struct dst_entry *dst)
1425{
1426 struct inet_request_sock *ireq;
1427 struct inet_sock *newinet;
1428 struct tcp_sock *newtp;
1429 struct sock *newsk;
1430#ifdef CONFIG_TCP_MD5SIG
1431 struct tcp_md5sig_key *key;
1432#endif
1433 struct ip_options_rcu *inet_opt;
1434
1435 if (sk_acceptq_is_full(sk))
1436 goto exit_overflow;
1437
1438 newsk = tcp_create_openreq_child(sk, req, skb);
1439 if (!newsk)
1440 goto exit_nonewsk;
1441
1442 newsk->sk_gso_type = SKB_GSO_TCPV4;
1443
1444 newtp = tcp_sk(newsk);
1445 newinet = inet_sk(newsk);
1446 ireq = inet_rsk(req);
1447 newinet->inet_daddr = ireq->rmt_addr;
1448 newinet->inet_rcv_saddr = ireq->loc_addr;
1449 newinet->inet_saddr = ireq->loc_addr;
1450 inet_opt = ireq->opt;
1451 rcu_assign_pointer(newinet->inet_opt, inet_opt);
1452 ireq->opt = NULL;
1453 newinet->mc_index = inet_iif(skb);
1454 newinet->mc_ttl = ip_hdr(skb)->ttl;
1455 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1456 if (inet_opt)
1457 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
1458 newinet->inet_id = newtp->write_seq ^ jiffies;
1459
1460 if (!dst && (dst = inet_csk_route_child_sock(sk, newsk, req)) == NULL)
1461 goto put_and_exit;
1462
1463 sk_setup_caps(newsk, dst);
1464
1465 tcp_mtup_init(newsk);
1466 tcp_sync_mss(newsk, dst_mtu(dst));
1467 newtp->advmss = dst_metric_advmss(dst);
1468 if (tcp_sk(sk)->rx_opt.user_mss &&
1469 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1470 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1471
1472 tcp_initialize_rcv_mss(newsk);
1473 if (tcp_rsk(req)->snt_synack)
1474 tcp_valid_rtt_meas(newsk,
1475 tcp_time_stamp - tcp_rsk(req)->snt_synack);
1476 newtp->total_retrans = req->retrans;
1477
1478#ifdef CONFIG_TCP_MD5SIG
1479 /* Copy over the MD5 key from the original socket */
1480 key = tcp_v4_md5_do_lookup(sk, newinet->inet_daddr);
1481 if (key != NULL) {
1482 /*
1483 * We're using one, so create a matching key
1484 * on the newsk structure. If we fail to get
1485 * memory, then we end up not copying the key
1486 * across. Shucks.
1487 */
1488 char *newkey = kmemdup(key->key, key->keylen, GFP_ATOMIC);
1489 if (newkey != NULL)
1490 tcp_v4_md5_do_add(newsk, newinet->inet_daddr,
1491 newkey, key->keylen);
1492 sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1493 }
1494#endif
1495
1496 if (__inet_inherit_port(sk, newsk) < 0)
1497 goto put_and_exit;
1498 __inet_hash_nolisten(newsk, NULL);
1499
1500 return newsk;
1501
1502exit_overflow:
1503 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1504exit_nonewsk:
1505 dst_release(dst);
1506exit:
1507 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1508 return NULL;
1509put_and_exit:
1510 sock_put(newsk);
1511 goto exit;
1512}
1513EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1514
1515static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1516{
1517 struct tcphdr *th = tcp_hdr(skb);
1518 const struct iphdr *iph = ip_hdr(skb);
1519 struct sock *nsk;
1520 struct request_sock **prev;
1521 /* Find possible connection requests. */
1522 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1523 iph->saddr, iph->daddr);
1524 if (req)
1525 return tcp_check_req(sk, skb, req, prev);
1526
1527 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1528 th->source, iph->daddr, th->dest, inet_iif(skb));
1529
1530 if (nsk) {
1531 if (nsk->sk_state != TCP_TIME_WAIT) {
1532 bh_lock_sock(nsk);
1533 return nsk;
1534 }
1535 inet_twsk_put(inet_twsk(nsk));
1536 return NULL;
1537 }
1538
1539#ifdef CONFIG_SYN_COOKIES
1540 if (!th->syn)
1541 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1542#endif
1543 return sk;
1544}
1545
1546static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1547{
1548 const struct iphdr *iph = ip_hdr(skb);
1549
1550 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1551 if (!tcp_v4_check(skb->len, iph->saddr,
1552 iph->daddr, skb->csum)) {
1553 skb->ip_summed = CHECKSUM_UNNECESSARY;
1554 return 0;
1555 }
1556 }
1557
1558 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1559 skb->len, IPPROTO_TCP, 0);
1560
1561 if (skb->len <= 76) {
1562 return __skb_checksum_complete(skb);
1563 }
1564 return 0;
1565}
1566
1567
1568/* The socket must have it's spinlock held when we get
1569 * here.
1570 *
1571 * We have a potential double-lock case here, so even when
1572 * doing backlog processing we use the BH locking scheme.
1573 * This is because we cannot sleep with the original spinlock
1574 * held.
1575 */
1576int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1577{
1578 struct sock *rsk;
1579#ifdef CONFIG_TCP_MD5SIG
1580 /*
1581 * We really want to reject the packet as early as possible
1582 * if:
1583 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1584 * o There is an MD5 option and we're not expecting one
1585 */
1586 if (tcp_v4_inbound_md5_hash(sk, skb))
1587 goto discard;
1588#endif
1589
1590 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1591 sock_rps_save_rxhash(sk, skb->rxhash);
1592 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1593 rsk = sk;
1594 goto reset;
1595 }
1596 return 0;
1597 }
1598
1599 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1600 goto csum_err;
1601
1602 if (sk->sk_state == TCP_LISTEN) {
1603 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1604 if (!nsk)
1605 goto discard;
1606
1607 if (nsk != sk) {
1608 sock_rps_save_rxhash(nsk, skb->rxhash);
1609 if (tcp_child_process(sk, nsk, skb)) {
1610 rsk = nsk;
1611 goto reset;
1612 }
1613 return 0;
1614 }
1615 } else
1616 sock_rps_save_rxhash(sk, skb->rxhash);
1617
1618 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1619 rsk = sk;
1620 goto reset;
1621 }
1622 return 0;
1623
1624reset:
1625 tcp_v4_send_reset(rsk, skb);
1626discard:
1627 kfree_skb(skb);
1628 /* Be careful here. If this function gets more complicated and
1629 * gcc suffers from register pressure on the x86, sk (in %ebx)
1630 * might be destroyed here. This current version compiles correctly,
1631 * but you have been warned.
1632 */
1633 return 0;
1634
1635csum_err:
1636 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1637 goto discard;
1638}
1639EXPORT_SYMBOL(tcp_v4_do_rcv);
1640
1641/*
1642 * From tcp_input.c
1643 */
1644
1645int tcp_v4_rcv(struct sk_buff *skb)
1646{
1647 const struct iphdr *iph;
1648 struct tcphdr *th;
1649 struct sock *sk;
1650 int ret;
1651 struct net *net = dev_net(skb->dev);
1652
1653 if (skb->pkt_type != PACKET_HOST)
1654 goto discard_it;
1655
1656 /* Count it even if it's bad */
1657 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1658
1659 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1660 goto discard_it;
1661
1662 th = tcp_hdr(skb);
1663
1664 if (th->doff < sizeof(struct tcphdr) / 4)
1665 goto bad_packet;
1666 if (!pskb_may_pull(skb, th->doff * 4))
1667 goto discard_it;
1668
1669 /* An explanation is required here, I think.
1670 * Packet length and doff are validated by header prediction,
1671 * provided case of th->doff==0 is eliminated.
1672 * So, we defer the checks. */
1673 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1674 goto bad_packet;
1675
1676 th = tcp_hdr(skb);
1677 iph = ip_hdr(skb);
1678 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1679 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1680 skb->len - th->doff * 4);
1681 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1682 TCP_SKB_CB(skb)->when = 0;
1683 TCP_SKB_CB(skb)->flags = iph->tos;
1684 TCP_SKB_CB(skb)->sacked = 0;
1685
1686 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1687 if (!sk)
1688 goto no_tcp_socket;
1689
1690process:
1691 if (sk->sk_state == TCP_TIME_WAIT)
1692 goto do_time_wait;
1693
1694 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
1695 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1696 goto discard_and_relse;
1697 }
1698
1699 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1700 goto discard_and_relse;
1701 nf_reset(skb);
1702
1703 if (sk_filter(sk, skb))
1704 goto discard_and_relse;
1705
1706 skb->dev = NULL;
1707
1708 bh_lock_sock_nested(sk);
1709 ret = 0;
1710 if (!sock_owned_by_user(sk)) {
1711#ifdef CONFIG_NET_DMA
1712 struct tcp_sock *tp = tcp_sk(sk);
1713 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
1714 tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
1715 if (tp->ucopy.dma_chan)
1716 ret = tcp_v4_do_rcv(sk, skb);
1717 else
1718#endif
1719 {
1720 if (!tcp_prequeue(sk, skb))
1721 ret = tcp_v4_do_rcv(sk, skb);
1722 }
1723 } else if (unlikely(sk_add_backlog(sk, skb))) {
1724 bh_unlock_sock(sk);
1725 NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
1726 goto discard_and_relse;
1727 }
1728 bh_unlock_sock(sk);
1729
1730 sock_put(sk);
1731
1732 return ret;
1733
1734no_tcp_socket:
1735 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1736 goto discard_it;
1737
1738 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1739bad_packet:
1740 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1741 } else {
1742 tcp_v4_send_reset(NULL, skb);
1743 }
1744
1745discard_it:
1746 /* Discard frame. */
1747 kfree_skb(skb);
1748 return 0;
1749
1750discard_and_relse:
1751 sock_put(sk);
1752 goto discard_it;
1753
1754do_time_wait:
1755 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1756 inet_twsk_put(inet_twsk(sk));
1757 goto discard_it;
1758 }
1759
1760 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1761 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1762 inet_twsk_put(inet_twsk(sk));
1763 goto discard_it;
1764 }
1765 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1766 case TCP_TW_SYN: {
1767 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1768 &tcp_hashinfo,
1769 iph->daddr, th->dest,
1770 inet_iif(skb));
1771 if (sk2) {
1772 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
1773 inet_twsk_put(inet_twsk(sk));
1774 sk = sk2;
1775 goto process;
1776 }
1777 /* Fall through to ACK */
1778 }
1779 case TCP_TW_ACK:
1780 tcp_v4_timewait_ack(sk, skb);
1781 break;
1782 case TCP_TW_RST:
1783 goto no_tcp_socket;
1784 case TCP_TW_SUCCESS:;
1785 }
1786 goto discard_it;
1787}
1788
1789struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it)
1790{
1791 struct rtable *rt = (struct rtable *) __sk_dst_get(sk);
1792 struct inet_sock *inet = inet_sk(sk);
1793 struct inet_peer *peer;
1794
1795 if (!rt ||
1796 inet->cork.fl.u.ip4.daddr != inet->inet_daddr) {
1797 peer = inet_getpeer_v4(inet->inet_daddr, 1);
1798 *release_it = true;
1799 } else {
1800 if (!rt->peer)
1801 rt_bind_peer(rt, inet->inet_daddr, 1);
1802 peer = rt->peer;
1803 *release_it = false;
1804 }
1805
1806 return peer;
1807}
1808EXPORT_SYMBOL(tcp_v4_get_peer);
1809
1810void *tcp_v4_tw_get_peer(struct sock *sk)
1811{
1812 struct inet_timewait_sock *tw = inet_twsk(sk);
1813
1814 return inet_getpeer_v4(tw->tw_daddr, 1);
1815}
1816EXPORT_SYMBOL(tcp_v4_tw_get_peer);
1817
1818static struct timewait_sock_ops tcp_timewait_sock_ops = {
1819 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1820 .twsk_unique = tcp_twsk_unique,
1821 .twsk_destructor= tcp_twsk_destructor,
1822 .twsk_getpeer = tcp_v4_tw_get_peer,
1823};
1824
1825const struct inet_connection_sock_af_ops ipv4_specific = {
1826 .queue_xmit = ip_queue_xmit,
1827 .send_check = tcp_v4_send_check,
1828 .rebuild_header = inet_sk_rebuild_header,
1829 .conn_request = tcp_v4_conn_request,
1830 .syn_recv_sock = tcp_v4_syn_recv_sock,
1831 .get_peer = tcp_v4_get_peer,
1832 .net_header_len = sizeof(struct iphdr),
1833 .setsockopt = ip_setsockopt,
1834 .getsockopt = ip_getsockopt,
1835 .addr2sockaddr = inet_csk_addr2sockaddr,
1836 .sockaddr_len = sizeof(struct sockaddr_in),
1837 .bind_conflict = inet_csk_bind_conflict,
1838#ifdef CONFIG_COMPAT
1839 .compat_setsockopt = compat_ip_setsockopt,
1840 .compat_getsockopt = compat_ip_getsockopt,
1841#endif
1842};
1843EXPORT_SYMBOL(ipv4_specific);
1844
1845#ifdef CONFIG_TCP_MD5SIG
1846static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1847 .md5_lookup = tcp_v4_md5_lookup,
1848 .calc_md5_hash = tcp_v4_md5_hash_skb,
1849 .md5_add = tcp_v4_md5_add_func,
1850 .md5_parse = tcp_v4_parse_md5_keys,
1851};
1852#endif
1853
1854/* NOTE: A lot of things set to zero explicitly by call to
1855 * sk_alloc() so need not be done here.
1856 */
1857static int tcp_v4_init_sock(struct sock *sk)
1858{
1859 struct inet_connection_sock *icsk = inet_csk(sk);
1860 struct tcp_sock *tp = tcp_sk(sk);
1861
1862 skb_queue_head_init(&tp->out_of_order_queue);
1863 tcp_init_xmit_timers(sk);
1864 tcp_prequeue_init(tp);
1865
1866 icsk->icsk_rto = TCP_TIMEOUT_INIT;
1867 tp->mdev = TCP_TIMEOUT_INIT;
1868
1869 /* So many TCP implementations out there (incorrectly) count the
1870 * initial SYN frame in their delayed-ACK and congestion control
1871 * algorithms that we must have the following bandaid to talk
1872 * efficiently to them. -DaveM
1873 */
1874 tp->snd_cwnd = TCP_INIT_CWND;
1875
1876 /* See draft-stevens-tcpca-spec-01 for discussion of the
1877 * initialization of these values.
1878 */
1879 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
1880 tp->snd_cwnd_clamp = ~0;
1881 tp->mss_cache = TCP_MSS_DEFAULT;
1882
1883 tp->reordering = sysctl_tcp_reordering;
1884 icsk->icsk_ca_ops = &tcp_init_congestion_ops;
1885
1886 sk->sk_state = TCP_CLOSE;
1887
1888 sk->sk_write_space = sk_stream_write_space;
1889 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1890
1891 icsk->icsk_af_ops = &ipv4_specific;
1892 icsk->icsk_sync_mss = tcp_sync_mss;
1893#ifdef CONFIG_TCP_MD5SIG
1894 tp->af_specific = &tcp_sock_ipv4_specific;
1895#endif
1896
1897 /* TCP Cookie Transactions */
1898 if (sysctl_tcp_cookie_size > 0) {
1899 /* Default, cookies without s_data_payload. */
1900 tp->cookie_values =
1901 kzalloc(sizeof(*tp->cookie_values),
1902 sk->sk_allocation);
1903 if (tp->cookie_values != NULL)
1904 kref_init(&tp->cookie_values->kref);
1905 }
1906 /* Presumed zeroed, in order of appearance:
1907 * cookie_in_always, cookie_out_never,
1908 * s_data_constant, s_data_in, s_data_out
1909 */
1910 sk->sk_sndbuf = sysctl_tcp_wmem[1];
1911 sk->sk_rcvbuf = sysctl_tcp_rmem[1];
1912
1913 local_bh_disable();
1914 percpu_counter_inc(&tcp_sockets_allocated);
1915 local_bh_enable();
1916
1917 return 0;
1918}
1919
1920void tcp_v4_destroy_sock(struct sock *sk)
1921{
1922 struct tcp_sock *tp = tcp_sk(sk);
1923
1924 tcp_clear_xmit_timers(sk);
1925
1926 tcp_cleanup_congestion_control(sk);
1927
1928 /* Cleanup up the write buffer. */
1929 tcp_write_queue_purge(sk);
1930
1931 /* Cleans up our, hopefully empty, out_of_order_queue. */
1932 __skb_queue_purge(&tp->out_of_order_queue);
1933
1934#ifdef CONFIG_TCP_MD5SIG
1935 /* Clean up the MD5 key list, if any */
1936 if (tp->md5sig_info) {
1937 tcp_v4_clear_md5_list(sk);
1938 kfree(tp->md5sig_info);
1939 tp->md5sig_info = NULL;
1940 }
1941#endif
1942
1943#ifdef CONFIG_NET_DMA
1944 /* Cleans up our sk_async_wait_queue */
1945 __skb_queue_purge(&sk->sk_async_wait_queue);
1946#endif
1947
1948 /* Clean prequeue, it must be empty really */
1949 __skb_queue_purge(&tp->ucopy.prequeue);
1950
1951 /* Clean up a referenced TCP bind bucket. */
1952 if (inet_csk(sk)->icsk_bind_hash)
1953 inet_put_port(sk);
1954
1955 /*
1956 * If sendmsg cached page exists, toss it.
1957 */
1958 if (sk->sk_sndmsg_page) {
1959 __free_page(sk->sk_sndmsg_page);
1960 sk->sk_sndmsg_page = NULL;
1961 }
1962
1963 /* TCP Cookie Transactions */
1964 if (tp->cookie_values != NULL) {
1965 kref_put(&tp->cookie_values->kref,
1966 tcp_cookie_values_release);
1967 tp->cookie_values = NULL;
1968 }
1969
1970 percpu_counter_dec(&tcp_sockets_allocated);
1971}
1972EXPORT_SYMBOL(tcp_v4_destroy_sock);
1973
1974#ifdef CONFIG_PROC_FS
1975/* Proc filesystem TCP sock list dumping. */
1976
1977static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
1978{
1979 return hlist_nulls_empty(head) ? NULL :
1980 list_entry(head->first, struct inet_timewait_sock, tw_node);
1981}
1982
1983static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
1984{
1985 return !is_a_nulls(tw->tw_node.next) ?
1986 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
1987}
1988
1989/*
1990 * Get next listener socket follow cur. If cur is NULL, get first socket
1991 * starting from bucket given in st->bucket; when st->bucket is zero the
1992 * very first socket in the hash table is returned.
1993 */
1994static void *listening_get_next(struct seq_file *seq, void *cur)
1995{
1996 struct inet_connection_sock *icsk;
1997 struct hlist_nulls_node *node;
1998 struct sock *sk = cur;
1999 struct inet_listen_hashbucket *ilb;
2000 struct tcp_iter_state *st = seq->private;
2001 struct net *net = seq_file_net(seq);
2002
2003 if (!sk) {
2004 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2005 spin_lock_bh(&ilb->lock);
2006 sk = sk_nulls_head(&ilb->head);
2007 st->offset = 0;
2008 goto get_sk;
2009 }
2010 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2011 ++st->num;
2012 ++st->offset;
2013
2014 if (st->state == TCP_SEQ_STATE_OPENREQ) {
2015 struct request_sock *req = cur;
2016
2017 icsk = inet_csk(st->syn_wait_sk);
2018 req = req->dl_next;
2019 while (1) {
2020 while (req) {
2021 if (req->rsk_ops->family == st->family) {
2022 cur = req;
2023 goto out;
2024 }
2025 req = req->dl_next;
2026 }
2027 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
2028 break;
2029get_req:
2030 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
2031 }
2032 sk = sk_nulls_next(st->syn_wait_sk);
2033 st->state = TCP_SEQ_STATE_LISTENING;
2034 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2035 } else {
2036 icsk = inet_csk(sk);
2037 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2038 if (reqsk_queue_len(&icsk->icsk_accept_queue))
2039 goto start_req;
2040 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2041 sk = sk_nulls_next(sk);
2042 }
2043get_sk:
2044 sk_nulls_for_each_from(sk, node) {
2045 if (!net_eq(sock_net(sk), net))
2046 continue;
2047 if (sk->sk_family == st->family) {
2048 cur = sk;
2049 goto out;
2050 }
2051 icsk = inet_csk(sk);
2052 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2053 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
2054start_req:
2055 st->uid = sock_i_uid(sk);
2056 st->syn_wait_sk = sk;
2057 st->state = TCP_SEQ_STATE_OPENREQ;
2058 st->sbucket = 0;
2059 goto get_req;
2060 }
2061 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2062 }
2063 spin_unlock_bh(&ilb->lock);
2064 st->offset = 0;
2065 if (++st->bucket < INET_LHTABLE_SIZE) {
2066 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2067 spin_lock_bh(&ilb->lock);
2068 sk = sk_nulls_head(&ilb->head);
2069 goto get_sk;
2070 }
2071 cur = NULL;
2072out:
2073 return cur;
2074}
2075
2076static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
2077{
2078 struct tcp_iter_state *st = seq->private;
2079 void *rc;
2080
2081 st->bucket = 0;
2082 st->offset = 0;
2083 rc = listening_get_next(seq, NULL);
2084
2085 while (rc && *pos) {
2086 rc = listening_get_next(seq, rc);
2087 --*pos;
2088 }
2089 return rc;
2090}
2091
2092static inline int empty_bucket(struct tcp_iter_state *st)
2093{
2094 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
2095 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
2096}
2097
2098/*
2099 * Get first established socket starting from bucket given in st->bucket.
2100 * If st->bucket is zero, the very first socket in the hash is returned.
2101 */
2102static void *established_get_first(struct seq_file *seq)
2103{
2104 struct tcp_iter_state *st = seq->private;
2105 struct net *net = seq_file_net(seq);
2106 void *rc = NULL;
2107
2108 st->offset = 0;
2109 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
2110 struct sock *sk;
2111 struct hlist_nulls_node *node;
2112 struct inet_timewait_sock *tw;
2113 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
2114
2115 /* Lockless fast path for the common case of empty buckets */
2116 if (empty_bucket(st))
2117 continue;
2118
2119 spin_lock_bh(lock);
2120 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2121 if (sk->sk_family != st->family ||
2122 !net_eq(sock_net(sk), net)) {
2123 continue;
2124 }
2125 rc = sk;
2126 goto out;
2127 }
2128 st->state = TCP_SEQ_STATE_TIME_WAIT;
2129 inet_twsk_for_each(tw, node,
2130 &tcp_hashinfo.ehash[st->bucket].twchain) {
2131 if (tw->tw_family != st->family ||
2132 !net_eq(twsk_net(tw), net)) {
2133 continue;
2134 }
2135 rc = tw;
2136 goto out;
2137 }
2138 spin_unlock_bh(lock);
2139 st->state = TCP_SEQ_STATE_ESTABLISHED;
2140 }
2141out:
2142 return rc;
2143}
2144
2145static void *established_get_next(struct seq_file *seq, void *cur)
2146{
2147 struct sock *sk = cur;
2148 struct inet_timewait_sock *tw;
2149 struct hlist_nulls_node *node;
2150 struct tcp_iter_state *st = seq->private;
2151 struct net *net = seq_file_net(seq);
2152
2153 ++st->num;
2154 ++st->offset;
2155
2156 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2157 tw = cur;
2158 tw = tw_next(tw);
2159get_tw:
2160 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2161 tw = tw_next(tw);
2162 }
2163 if (tw) {
2164 cur = tw;
2165 goto out;
2166 }
2167 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2168 st->state = TCP_SEQ_STATE_ESTABLISHED;
2169
2170 /* Look for next non empty bucket */
2171 st->offset = 0;
2172 while (++st->bucket <= tcp_hashinfo.ehash_mask &&
2173 empty_bucket(st))
2174 ;
2175 if (st->bucket > tcp_hashinfo.ehash_mask)
2176 return NULL;
2177
2178 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2179 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2180 } else
2181 sk = sk_nulls_next(sk);
2182
2183 sk_nulls_for_each_from(sk, node) {
2184 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2185 goto found;
2186 }
2187
2188 st->state = TCP_SEQ_STATE_TIME_WAIT;
2189 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2190 goto get_tw;
2191found:
2192 cur = sk;
2193out:
2194 return cur;
2195}
2196
2197static void *established_get_idx(struct seq_file *seq, loff_t pos)
2198{
2199 struct tcp_iter_state *st = seq->private;
2200 void *rc;
2201
2202 st->bucket = 0;
2203 rc = established_get_first(seq);
2204
2205 while (rc && pos) {
2206 rc = established_get_next(seq, rc);
2207 --pos;
2208 }
2209 return rc;
2210}
2211
2212static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2213{
2214 void *rc;
2215 struct tcp_iter_state *st = seq->private;
2216
2217 st->state = TCP_SEQ_STATE_LISTENING;
2218 rc = listening_get_idx(seq, &pos);
2219
2220 if (!rc) {
2221 st->state = TCP_SEQ_STATE_ESTABLISHED;
2222 rc = established_get_idx(seq, pos);
2223 }
2224
2225 return rc;
2226}
2227
2228static void *tcp_seek_last_pos(struct seq_file *seq)
2229{
2230 struct tcp_iter_state *st = seq->private;
2231 int offset = st->offset;
2232 int orig_num = st->num;
2233 void *rc = NULL;
2234
2235 switch (st->state) {
2236 case TCP_SEQ_STATE_OPENREQ:
2237 case TCP_SEQ_STATE_LISTENING:
2238 if (st->bucket >= INET_LHTABLE_SIZE)
2239 break;
2240 st->state = TCP_SEQ_STATE_LISTENING;
2241 rc = listening_get_next(seq, NULL);
2242 while (offset-- && rc)
2243 rc = listening_get_next(seq, rc);
2244 if (rc)
2245 break;
2246 st->bucket = 0;
2247 /* Fallthrough */
2248 case TCP_SEQ_STATE_ESTABLISHED:
2249 case TCP_SEQ_STATE_TIME_WAIT:
2250 st->state = TCP_SEQ_STATE_ESTABLISHED;
2251 if (st->bucket > tcp_hashinfo.ehash_mask)
2252 break;
2253 rc = established_get_first(seq);
2254 while (offset-- && rc)
2255 rc = established_get_next(seq, rc);
2256 }
2257
2258 st->num = orig_num;
2259
2260 return rc;
2261}
2262
2263static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2264{
2265 struct tcp_iter_state *st = seq->private;
2266 void *rc;
2267
2268 if (*pos && *pos == st->last_pos) {
2269 rc = tcp_seek_last_pos(seq);
2270 if (rc)
2271 goto out;
2272 }
2273
2274 st->state = TCP_SEQ_STATE_LISTENING;
2275 st->num = 0;
2276 st->bucket = 0;
2277 st->offset = 0;
2278 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2279
2280out:
2281 st->last_pos = *pos;
2282 return rc;
2283}
2284
2285static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2286{
2287 struct tcp_iter_state *st = seq->private;
2288 void *rc = NULL;
2289
2290 if (v == SEQ_START_TOKEN) {
2291 rc = tcp_get_idx(seq, 0);
2292 goto out;
2293 }
2294
2295 switch (st->state) {
2296 case TCP_SEQ_STATE_OPENREQ:
2297 case TCP_SEQ_STATE_LISTENING:
2298 rc = listening_get_next(seq, v);
2299 if (!rc) {
2300 st->state = TCP_SEQ_STATE_ESTABLISHED;
2301 st->bucket = 0;
2302 st->offset = 0;
2303 rc = established_get_first(seq);
2304 }
2305 break;
2306 case TCP_SEQ_STATE_ESTABLISHED:
2307 case TCP_SEQ_STATE_TIME_WAIT:
2308 rc = established_get_next(seq, v);
2309 break;
2310 }
2311out:
2312 ++*pos;
2313 st->last_pos = *pos;
2314 return rc;
2315}
2316
2317static void tcp_seq_stop(struct seq_file *seq, void *v)
2318{
2319 struct tcp_iter_state *st = seq->private;
2320
2321 switch (st->state) {
2322 case TCP_SEQ_STATE_OPENREQ:
2323 if (v) {
2324 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2325 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2326 }
2327 case TCP_SEQ_STATE_LISTENING:
2328 if (v != SEQ_START_TOKEN)
2329 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2330 break;
2331 case TCP_SEQ_STATE_TIME_WAIT:
2332 case TCP_SEQ_STATE_ESTABLISHED:
2333 if (v)
2334 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2335 break;
2336 }
2337}
2338
2339static int tcp_seq_open(struct inode *inode, struct file *file)
2340{
2341 struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
2342 struct tcp_iter_state *s;
2343 int err;
2344
2345 err = seq_open_net(inode, file, &afinfo->seq_ops,
2346 sizeof(struct tcp_iter_state));
2347 if (err < 0)
2348 return err;
2349
2350 s = ((struct seq_file *)file->private_data)->private;
2351 s->family = afinfo->family;
2352 s->last_pos = 0;
2353 return 0;
2354}
2355
2356int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2357{
2358 int rc = 0;
2359 struct proc_dir_entry *p;
2360
2361 afinfo->seq_fops.open = tcp_seq_open;
2362 afinfo->seq_fops.read = seq_read;
2363 afinfo->seq_fops.llseek = seq_lseek;
2364 afinfo->seq_fops.release = seq_release_net;
2365
2366 afinfo->seq_ops.start = tcp_seq_start;
2367 afinfo->seq_ops.next = tcp_seq_next;
2368 afinfo->seq_ops.stop = tcp_seq_stop;
2369
2370 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2371 &afinfo->seq_fops, afinfo);
2372 if (!p)
2373 rc = -ENOMEM;
2374 return rc;
2375}
2376EXPORT_SYMBOL(tcp_proc_register);
2377
2378void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2379{
2380 proc_net_remove(net, afinfo->name);
2381}
2382EXPORT_SYMBOL(tcp_proc_unregister);
2383
2384static void get_openreq4(struct sock *sk, struct request_sock *req,
2385 struct seq_file *f, int i, int uid, int *len)
2386{
2387 const struct inet_request_sock *ireq = inet_rsk(req);
2388 int ttd = req->expires - jiffies;
2389
2390 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2391 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %pK%n",
2392 i,
2393 ireq->loc_addr,
2394 ntohs(inet_sk(sk)->inet_sport),
2395 ireq->rmt_addr,
2396 ntohs(ireq->rmt_port),
2397 TCP_SYN_RECV,
2398 0, 0, /* could print option size, but that is af dependent. */
2399 1, /* timers active (only the expire timer) */
2400 jiffies_to_clock_t(ttd),
2401 req->retrans,
2402 uid,
2403 0, /* non standard timer */
2404 0, /* open_requests have no inode */
2405 atomic_read(&sk->sk_refcnt),
2406 req,
2407 len);
2408}
2409
2410static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2411{
2412 int timer_active;
2413 unsigned long timer_expires;
2414 struct tcp_sock *tp = tcp_sk(sk);
2415 const struct inet_connection_sock *icsk = inet_csk(sk);
2416 struct inet_sock *inet = inet_sk(sk);
2417 __be32 dest = inet->inet_daddr;
2418 __be32 src = inet->inet_rcv_saddr;
2419 __u16 destp = ntohs(inet->inet_dport);
2420 __u16 srcp = ntohs(inet->inet_sport);
2421 int rx_queue;
2422
2423 if (icsk->icsk_pending == ICSK_TIME_RETRANS) {
2424 timer_active = 1;
2425 timer_expires = icsk->icsk_timeout;
2426 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2427 timer_active = 4;
2428 timer_expires = icsk->icsk_timeout;
2429 } else if (timer_pending(&sk->sk_timer)) {
2430 timer_active = 2;
2431 timer_expires = sk->sk_timer.expires;
2432 } else {
2433 timer_active = 0;
2434 timer_expires = jiffies;
2435 }
2436
2437 if (sk->sk_state == TCP_LISTEN)
2438 rx_queue = sk->sk_ack_backlog;
2439 else
2440 /*
2441 * because we dont lock socket, we might find a transient negative value
2442 */
2443 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
2444
2445 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2446 "%08X %5d %8d %lu %d %pK %lu %lu %u %u %d%n",
2447 i, src, srcp, dest, destp, sk->sk_state,
2448 tp->write_seq - tp->snd_una,
2449 rx_queue,
2450 timer_active,
2451 jiffies_to_clock_t(timer_expires - jiffies),
2452 icsk->icsk_retransmits,
2453 sock_i_uid(sk),
2454 icsk->icsk_probes_out,
2455 sock_i_ino(sk),
2456 atomic_read(&sk->sk_refcnt), sk,
2457 jiffies_to_clock_t(icsk->icsk_rto),
2458 jiffies_to_clock_t(icsk->icsk_ack.ato),
2459 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2460 tp->snd_cwnd,
2461 tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh,
2462 len);
2463}
2464
2465static void get_timewait4_sock(struct inet_timewait_sock *tw,
2466 struct seq_file *f, int i, int *len)
2467{
2468 __be32 dest, src;
2469 __u16 destp, srcp;
2470 int ttd = tw->tw_ttd - jiffies;
2471
2472 if (ttd < 0)
2473 ttd = 0;
2474
2475 dest = tw->tw_daddr;
2476 src = tw->tw_rcv_saddr;
2477 destp = ntohs(tw->tw_dport);
2478 srcp = ntohs(tw->tw_sport);
2479
2480 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2481 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
2482 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2483 3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
2484 atomic_read(&tw->tw_refcnt), tw, len);
2485}
2486
2487#define TMPSZ 150
2488
2489static int tcp4_seq_show(struct seq_file *seq, void *v)
2490{
2491 struct tcp_iter_state *st;
2492 int len;
2493
2494 if (v == SEQ_START_TOKEN) {
2495 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2496 " sl local_address rem_address st tx_queue "
2497 "rx_queue tr tm->when retrnsmt uid timeout "
2498 "inode");
2499 goto out;
2500 }
2501 st = seq->private;
2502
2503 switch (st->state) {
2504 case TCP_SEQ_STATE_LISTENING:
2505 case TCP_SEQ_STATE_ESTABLISHED:
2506 get_tcp4_sock(v, seq, st->num, &len);
2507 break;
2508 case TCP_SEQ_STATE_OPENREQ:
2509 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2510 break;
2511 case TCP_SEQ_STATE_TIME_WAIT:
2512 get_timewait4_sock(v, seq, st->num, &len);
2513 break;
2514 }
2515 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2516out:
2517 return 0;
2518}
2519
2520static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2521 .name = "tcp",
2522 .family = AF_INET,
2523 .seq_fops = {
2524 .owner = THIS_MODULE,
2525 },
2526 .seq_ops = {
2527 .show = tcp4_seq_show,
2528 },
2529};
2530
2531static int __net_init tcp4_proc_init_net(struct net *net)
2532{
2533 return tcp_proc_register(net, &tcp4_seq_afinfo);
2534}
2535
2536static void __net_exit tcp4_proc_exit_net(struct net *net)
2537{
2538 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2539}
2540
2541static struct pernet_operations tcp4_net_ops = {
2542 .init = tcp4_proc_init_net,
2543 .exit = tcp4_proc_exit_net,
2544};
2545
2546int __init tcp4_proc_init(void)
2547{
2548 return register_pernet_subsys(&tcp4_net_ops);
2549}
2550
2551void tcp4_proc_exit(void)
2552{
2553 unregister_pernet_subsys(&tcp4_net_ops);
2554}
2555#endif /* CONFIG_PROC_FS */
2556
2557struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
2558{
2559 const struct iphdr *iph = skb_gro_network_header(skb);
2560
2561 switch (skb->ip_summed) {
2562 case CHECKSUM_COMPLETE:
2563 if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
2564 skb->csum)) {
2565 skb->ip_summed = CHECKSUM_UNNECESSARY;
2566 break;
2567 }
2568
2569 /* fall through */
2570 case CHECKSUM_NONE:
2571 NAPI_GRO_CB(skb)->flush = 1;
2572 return NULL;
2573 }
2574
2575 return tcp_gro_receive(head, skb);
2576}
2577
2578int tcp4_gro_complete(struct sk_buff *skb)
2579{
2580 const struct iphdr *iph = ip_hdr(skb);
2581 struct tcphdr *th = tcp_hdr(skb);
2582
2583 th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
2584 iph->saddr, iph->daddr, 0);
2585 skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
2586
2587 return tcp_gro_complete(skb);
2588}
2589
2590struct proto tcp_prot = {
2591 .name = "TCP",
2592 .owner = THIS_MODULE,
2593 .close = tcp_close,
2594 .connect = tcp_v4_connect,
2595 .disconnect = tcp_disconnect,
2596 .accept = inet_csk_accept,
2597 .ioctl = tcp_ioctl,
2598 .init = tcp_v4_init_sock,
2599 .destroy = tcp_v4_destroy_sock,
2600 .shutdown = tcp_shutdown,
2601 .setsockopt = tcp_setsockopt,
2602 .getsockopt = tcp_getsockopt,
2603 .recvmsg = tcp_recvmsg,
2604 .sendmsg = tcp_sendmsg,
2605 .sendpage = tcp_sendpage,
2606 .backlog_rcv = tcp_v4_do_rcv,
2607 .hash = inet_hash,
2608 .unhash = inet_unhash,
2609 .get_port = inet_csk_get_port,
2610 .enter_memory_pressure = tcp_enter_memory_pressure,
2611 .sockets_allocated = &tcp_sockets_allocated,
2612 .orphan_count = &tcp_orphan_count,
2613 .memory_allocated = &tcp_memory_allocated,
2614 .memory_pressure = &tcp_memory_pressure,
2615 .sysctl_mem = sysctl_tcp_mem,
2616 .sysctl_wmem = sysctl_tcp_wmem,
2617 .sysctl_rmem = sysctl_tcp_rmem,
2618 .max_header = MAX_TCP_HEADER,
2619 .obj_size = sizeof(struct tcp_sock),
2620 .slab_flags = SLAB_DESTROY_BY_RCU,
2621 .twsk_prot = &tcp_timewait_sock_ops,
2622 .rsk_prot = &tcp_request_sock_ops,
2623 .h.hashinfo = &tcp_hashinfo,
2624 .no_autobind = true,
2625#ifdef CONFIG_COMPAT
2626 .compat_setsockopt = compat_tcp_setsockopt,
2627 .compat_getsockopt = compat_tcp_getsockopt,
2628#endif
2629};
2630EXPORT_SYMBOL(tcp_prot);
2631
2632
2633static int __net_init tcp_sk_init(struct net *net)
2634{
2635 return inet_ctl_sock_create(&net->ipv4.tcp_sock,
2636 PF_INET, SOCK_RAW, IPPROTO_TCP, net);
2637}
2638
2639static void __net_exit tcp_sk_exit(struct net *net)
2640{
2641 inet_ctl_sock_destroy(net->ipv4.tcp_sock);
2642}
2643
2644static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
2645{
2646 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2647}
2648
2649static struct pernet_operations __net_initdata tcp_sk_ops = {
2650 .init = tcp_sk_init,
2651 .exit = tcp_sk_exit,
2652 .exit_batch = tcp_sk_exit_batch,
2653};
2654
2655void __init tcp_v4_init(void)
2656{
2657 inet_hashinfo_init(&tcp_hashinfo);
2658 if (register_pernet_subsys(&tcp_sk_ops))
2659 panic("Failed to create the TCP control socket.\n");
2660}
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#define pr_fmt(fmt) "TCP: " fmt
54
55#include <linux/bottom_half.h>
56#include <linux/types.h>
57#include <linux/fcntl.h>
58#include <linux/module.h>
59#include <linux/random.h>
60#include <linux/cache.h>
61#include <linux/jhash.h>
62#include <linux/init.h>
63#include <linux/times.h>
64#include <linux/slab.h>
65
66#include <net/net_namespace.h>
67#include <net/icmp.h>
68#include <net/inet_hashtables.h>
69#include <net/tcp.h>
70#include <net/transp_v6.h>
71#include <net/ipv6.h>
72#include <net/inet_common.h>
73#include <net/timewait_sock.h>
74#include <net/xfrm.h>
75#include <net/netdma.h>
76#include <net/secure_seq.h>
77#include <net/tcp_memcontrol.h>
78#include <net/busy_poll.h>
79
80#include <linux/inet.h>
81#include <linux/ipv6.h>
82#include <linux/stddef.h>
83#include <linux/proc_fs.h>
84#include <linux/seq_file.h>
85
86#include <linux/crypto.h>
87#include <linux/scatterlist.h>
88
89int sysctl_tcp_tw_reuse __read_mostly;
90int sysctl_tcp_low_latency __read_mostly;
91EXPORT_SYMBOL(sysctl_tcp_low_latency);
92
93
94#ifdef CONFIG_TCP_MD5SIG
95static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
96 __be32 daddr, __be32 saddr, const struct tcphdr *th);
97#endif
98
99struct inet_hashinfo tcp_hashinfo;
100EXPORT_SYMBOL(tcp_hashinfo);
101
102static inline __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
103{
104 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
105 ip_hdr(skb)->saddr,
106 tcp_hdr(skb)->dest,
107 tcp_hdr(skb)->source);
108}
109
110int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
111{
112 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
113 struct tcp_sock *tp = tcp_sk(sk);
114
115 /* With PAWS, it is safe from the viewpoint
116 of data integrity. Even without PAWS it is safe provided sequence
117 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
118
119 Actually, the idea is close to VJ's one, only timestamp cache is
120 held not per host, but per port pair and TW bucket is used as state
121 holder.
122
123 If TW bucket has been already destroyed we fall back to VJ's scheme
124 and use initial timestamp retrieved from peer table.
125 */
126 if (tcptw->tw_ts_recent_stamp &&
127 (twp == NULL || (sysctl_tcp_tw_reuse &&
128 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
129 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
130 if (tp->write_seq == 0)
131 tp->write_seq = 1;
132 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
133 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
134 sock_hold(sktw);
135 return 1;
136 }
137
138 return 0;
139}
140EXPORT_SYMBOL_GPL(tcp_twsk_unique);
141
142/* This will initiate an outgoing connection. */
143int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
144{
145 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
146 struct inet_sock *inet = inet_sk(sk);
147 struct tcp_sock *tp = tcp_sk(sk);
148 __be16 orig_sport, orig_dport;
149 __be32 daddr, nexthop;
150 struct flowi4 *fl4;
151 struct rtable *rt;
152 int err;
153 struct ip_options_rcu *inet_opt;
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 inet_opt = rcu_dereference_protected(inet->inet_opt,
163 sock_owned_by_user(sk));
164 if (inet_opt && inet_opt->opt.srr) {
165 if (!daddr)
166 return -EINVAL;
167 nexthop = inet_opt->opt.faddr;
168 }
169
170 orig_sport = inet->inet_sport;
171 orig_dport = usin->sin_port;
172 fl4 = &inet->cork.fl.u.ip4;
173 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
174 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
175 IPPROTO_TCP,
176 orig_sport, orig_dport, sk);
177 if (IS_ERR(rt)) {
178 err = PTR_ERR(rt);
179 if (err == -ENETUNREACH)
180 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
181 return err;
182 }
183
184 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
185 ip_rt_put(rt);
186 return -ENETUNREACH;
187 }
188
189 if (!inet_opt || !inet_opt->opt.srr)
190 daddr = fl4->daddr;
191
192 if (!inet->inet_saddr)
193 inet->inet_saddr = fl4->saddr;
194 inet->inet_rcv_saddr = inet->inet_saddr;
195
196 if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
197 /* Reset inherited state */
198 tp->rx_opt.ts_recent = 0;
199 tp->rx_opt.ts_recent_stamp = 0;
200 if (likely(!tp->repair))
201 tp->write_seq = 0;
202 }
203
204 if (tcp_death_row.sysctl_tw_recycle &&
205 !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
206 tcp_fetch_timewait_stamp(sk, &rt->dst);
207
208 inet->inet_dport = usin->sin_port;
209 inet->inet_daddr = daddr;
210
211 inet_csk(sk)->icsk_ext_hdr_len = 0;
212 if (inet_opt)
213 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
214
215 tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
216
217 /* Socket identity is still unknown (sport may be zero).
218 * However we set state to SYN-SENT and not releasing socket
219 * lock select source port, enter ourselves into the hash tables and
220 * complete initialization after this.
221 */
222 tcp_set_state(sk, TCP_SYN_SENT);
223 err = inet_hash_connect(&tcp_death_row, sk);
224 if (err)
225 goto failure;
226
227 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
228 inet->inet_sport, inet->inet_dport, sk);
229 if (IS_ERR(rt)) {
230 err = PTR_ERR(rt);
231 rt = NULL;
232 goto failure;
233 }
234 /* OK, now commit destination to socket. */
235 sk->sk_gso_type = SKB_GSO_TCPV4;
236 sk_setup_caps(sk, &rt->dst);
237
238 if (!tp->write_seq && likely(!tp->repair))
239 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
240 inet->inet_daddr,
241 inet->inet_sport,
242 usin->sin_port);
243
244 inet->inet_id = tp->write_seq ^ jiffies;
245
246 err = tcp_connect(sk);
247
248 rt = NULL;
249 if (err)
250 goto failure;
251
252 return 0;
253
254failure:
255 /*
256 * This unhashes the socket and releases the local port,
257 * if necessary.
258 */
259 tcp_set_state(sk, TCP_CLOSE);
260 ip_rt_put(rt);
261 sk->sk_route_caps = 0;
262 inet->inet_dport = 0;
263 return err;
264}
265EXPORT_SYMBOL(tcp_v4_connect);
266
267/*
268 * This routine reacts to ICMP_FRAG_NEEDED mtu indications as defined in RFC1191.
269 * It can be called through tcp_release_cb() if socket was owned by user
270 * at the time tcp_v4_err() was called to handle ICMP message.
271 */
272static void tcp_v4_mtu_reduced(struct sock *sk)
273{
274 struct dst_entry *dst;
275 struct inet_sock *inet = inet_sk(sk);
276 u32 mtu = tcp_sk(sk)->mtu_info;
277
278 dst = inet_csk_update_pmtu(sk, mtu);
279 if (!dst)
280 return;
281
282 /* Something is about to be wrong... Remember soft error
283 * for the case, if this connection will not able to recover.
284 */
285 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
286 sk->sk_err_soft = EMSGSIZE;
287
288 mtu = dst_mtu(dst);
289
290 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
291 ip_sk_accept_pmtu(sk) &&
292 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
293 tcp_sync_mss(sk, mtu);
294
295 /* Resend the TCP packet because it's
296 * clear that the old packet has been
297 * dropped. This is the new "fast" path mtu
298 * discovery.
299 */
300 tcp_simple_retransmit(sk);
301 } /* else let the usual retransmit timer handle it */
302}
303
304static void do_redirect(struct sk_buff *skb, struct sock *sk)
305{
306 struct dst_entry *dst = __sk_dst_check(sk, 0);
307
308 if (dst)
309 dst->ops->redirect(dst, sk, skb);
310}
311
312/*
313 * This routine is called by the ICMP module when it gets some
314 * sort of error condition. If err < 0 then the socket should
315 * be closed and the error returned to the user. If err > 0
316 * it's just the icmp type << 8 | icmp code. After adjustment
317 * header points to the first 8 bytes of the tcp header. We need
318 * to find the appropriate port.
319 *
320 * The locking strategy used here is very "optimistic". When
321 * someone else accesses the socket the ICMP is just dropped
322 * and for some paths there is no check at all.
323 * A more general error queue to queue errors for later handling
324 * is probably better.
325 *
326 */
327
328void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
329{
330 const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
331 struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
332 struct inet_connection_sock *icsk;
333 struct tcp_sock *tp;
334 struct inet_sock *inet;
335 const int type = icmp_hdr(icmp_skb)->type;
336 const int code = icmp_hdr(icmp_skb)->code;
337 struct sock *sk;
338 struct sk_buff *skb;
339 struct request_sock *req;
340 __u32 seq;
341 __u32 remaining;
342 int err;
343 struct net *net = dev_net(icmp_skb->dev);
344
345 if (icmp_skb->len < (iph->ihl << 2) + 8) {
346 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
347 return;
348 }
349
350 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
351 iph->saddr, th->source, inet_iif(icmp_skb));
352 if (!sk) {
353 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
354 return;
355 }
356 if (sk->sk_state == TCP_TIME_WAIT) {
357 inet_twsk_put(inet_twsk(sk));
358 return;
359 }
360
361 bh_lock_sock(sk);
362 /* If too many ICMPs get dropped on busy
363 * servers this needs to be solved differently.
364 * We do take care of PMTU discovery (RFC1191) special case :
365 * we can receive locally generated ICMP messages while socket is held.
366 */
367 if (sock_owned_by_user(sk)) {
368 if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
369 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
370 }
371 if (sk->sk_state == TCP_CLOSE)
372 goto out;
373
374 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
375 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
376 goto out;
377 }
378
379 icsk = inet_csk(sk);
380 tp = tcp_sk(sk);
381 req = tp->fastopen_rsk;
382 seq = ntohl(th->seq);
383 if (sk->sk_state != TCP_LISTEN &&
384 !between(seq, tp->snd_una, tp->snd_nxt) &&
385 (req == NULL || seq != tcp_rsk(req)->snt_isn)) {
386 /* For a Fast Open socket, allow seq to be snt_isn. */
387 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
388 goto out;
389 }
390
391 switch (type) {
392 case ICMP_REDIRECT:
393 do_redirect(icmp_skb, sk);
394 goto out;
395 case ICMP_SOURCE_QUENCH:
396 /* Just silently ignore these. */
397 goto out;
398 case ICMP_PARAMETERPROB:
399 err = EPROTO;
400 break;
401 case ICMP_DEST_UNREACH:
402 if (code > NR_ICMP_UNREACH)
403 goto out;
404
405 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
406 /* We are not interested in TCP_LISTEN and open_requests
407 * (SYN-ACKs send out by Linux are always <576bytes so
408 * they should go through unfragmented).
409 */
410 if (sk->sk_state == TCP_LISTEN)
411 goto out;
412
413 tp->mtu_info = info;
414 if (!sock_owned_by_user(sk)) {
415 tcp_v4_mtu_reduced(sk);
416 } else {
417 if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
418 sock_hold(sk);
419 }
420 goto out;
421 }
422
423 err = icmp_err_convert[code].errno;
424 /* check if icmp_skb allows revert of backoff
425 * (see draft-zimmermann-tcp-lcd) */
426 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
427 break;
428 if (seq != tp->snd_una || !icsk->icsk_retransmits ||
429 !icsk->icsk_backoff)
430 break;
431
432 /* XXX (TFO) - revisit the following logic for TFO */
433
434 if (sock_owned_by_user(sk))
435 break;
436
437 icsk->icsk_backoff--;
438 inet_csk(sk)->icsk_rto = (tp->srtt_us ? __tcp_set_rto(tp) :
439 TCP_TIMEOUT_INIT) << icsk->icsk_backoff;
440 tcp_bound_rto(sk);
441
442 skb = tcp_write_queue_head(sk);
443 BUG_ON(!skb);
444
445 remaining = icsk->icsk_rto - min(icsk->icsk_rto,
446 tcp_time_stamp - TCP_SKB_CB(skb)->when);
447
448 if (remaining) {
449 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
450 remaining, TCP_RTO_MAX);
451 } else {
452 /* RTO revert clocked out retransmission.
453 * Will retransmit now */
454 tcp_retransmit_timer(sk);
455 }
456
457 break;
458 case ICMP_TIME_EXCEEDED:
459 err = EHOSTUNREACH;
460 break;
461 default:
462 goto out;
463 }
464
465 /* XXX (TFO) - if it's a TFO socket and has been accepted, rather
466 * than following the TCP_SYN_RECV case and closing the socket,
467 * we ignore the ICMP error and keep trying like a fully established
468 * socket. Is this the right thing to do?
469 */
470 if (req && req->sk == NULL)
471 goto out;
472
473 switch (sk->sk_state) {
474 struct request_sock *req, **prev;
475 case TCP_LISTEN:
476 if (sock_owned_by_user(sk))
477 goto out;
478
479 req = inet_csk_search_req(sk, &prev, th->dest,
480 iph->daddr, iph->saddr);
481 if (!req)
482 goto out;
483
484 /* ICMPs are not backlogged, hence we cannot get
485 an established socket here.
486 */
487 WARN_ON(req->sk);
488
489 if (seq != tcp_rsk(req)->snt_isn) {
490 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
491 goto out;
492 }
493
494 /*
495 * Still in SYN_RECV, just remove it silently.
496 * There is no good way to pass the error to the newly
497 * created socket, and POSIX does not want network
498 * errors returned from accept().
499 */
500 inet_csk_reqsk_queue_drop(sk, req, prev);
501 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
502 goto out;
503
504 case TCP_SYN_SENT:
505 case TCP_SYN_RECV: /* Cannot happen.
506 It can f.e. if SYNs crossed,
507 or Fast Open.
508 */
509 if (!sock_owned_by_user(sk)) {
510 sk->sk_err = err;
511
512 sk->sk_error_report(sk);
513
514 tcp_done(sk);
515 } else {
516 sk->sk_err_soft = err;
517 }
518 goto out;
519 }
520
521 /* If we've already connected we will keep trying
522 * until we time out, or the user gives up.
523 *
524 * rfc1122 4.2.3.9 allows to consider as hard errors
525 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
526 * but it is obsoleted by pmtu discovery).
527 *
528 * Note, that in modern internet, where routing is unreliable
529 * and in each dark corner broken firewalls sit, sending random
530 * errors ordered by their masters even this two messages finally lose
531 * their original sense (even Linux sends invalid PORT_UNREACHs)
532 *
533 * Now we are in compliance with RFCs.
534 * --ANK (980905)
535 */
536
537 inet = inet_sk(sk);
538 if (!sock_owned_by_user(sk) && inet->recverr) {
539 sk->sk_err = err;
540 sk->sk_error_report(sk);
541 } else { /* Only an error on timeout */
542 sk->sk_err_soft = err;
543 }
544
545out:
546 bh_unlock_sock(sk);
547 sock_put(sk);
548}
549
550void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
551{
552 struct tcphdr *th = tcp_hdr(skb);
553
554 if (skb->ip_summed == CHECKSUM_PARTIAL) {
555 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
556 skb->csum_start = skb_transport_header(skb) - skb->head;
557 skb->csum_offset = offsetof(struct tcphdr, check);
558 } else {
559 th->check = tcp_v4_check(skb->len, saddr, daddr,
560 csum_partial(th,
561 th->doff << 2,
562 skb->csum));
563 }
564}
565
566/* This routine computes an IPv4 TCP checksum. */
567void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
568{
569 const struct inet_sock *inet = inet_sk(sk);
570
571 __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
572}
573EXPORT_SYMBOL(tcp_v4_send_check);
574
575/*
576 * This routine will send an RST to the other tcp.
577 *
578 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
579 * for reset.
580 * Answer: if a packet caused RST, it is not for a socket
581 * existing in our system, if it is matched to a socket,
582 * it is just duplicate segment or bug in other side's TCP.
583 * So that we build reply only basing on parameters
584 * arrived with segment.
585 * Exception: precedence violation. We do not implement it in any case.
586 */
587
588static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
589{
590 const struct tcphdr *th = tcp_hdr(skb);
591 struct {
592 struct tcphdr th;
593#ifdef CONFIG_TCP_MD5SIG
594 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
595#endif
596 } rep;
597 struct ip_reply_arg arg;
598#ifdef CONFIG_TCP_MD5SIG
599 struct tcp_md5sig_key *key;
600 const __u8 *hash_location = NULL;
601 unsigned char newhash[16];
602 int genhash;
603 struct sock *sk1 = NULL;
604#endif
605 struct net *net;
606
607 /* Never send a reset in response to a reset. */
608 if (th->rst)
609 return;
610
611 if (skb_rtable(skb)->rt_type != RTN_LOCAL)
612 return;
613
614 /* Swap the send and the receive. */
615 memset(&rep, 0, sizeof(rep));
616 rep.th.dest = th->source;
617 rep.th.source = th->dest;
618 rep.th.doff = sizeof(struct tcphdr) / 4;
619 rep.th.rst = 1;
620
621 if (th->ack) {
622 rep.th.seq = th->ack_seq;
623 } else {
624 rep.th.ack = 1;
625 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
626 skb->len - (th->doff << 2));
627 }
628
629 memset(&arg, 0, sizeof(arg));
630 arg.iov[0].iov_base = (unsigned char *)&rep;
631 arg.iov[0].iov_len = sizeof(rep.th);
632
633#ifdef CONFIG_TCP_MD5SIG
634 hash_location = tcp_parse_md5sig_option(th);
635 if (!sk && hash_location) {
636 /*
637 * active side is lost. Try to find listening socket through
638 * source port, and then find md5 key through listening socket.
639 * we are not loose security here:
640 * Incoming packet is checked with md5 hash with finding key,
641 * no RST generated if md5 hash doesn't match.
642 */
643 sk1 = __inet_lookup_listener(dev_net(skb_dst(skb)->dev),
644 &tcp_hashinfo, ip_hdr(skb)->saddr,
645 th->source, ip_hdr(skb)->daddr,
646 ntohs(th->source), inet_iif(skb));
647 /* don't send rst if it can't find key */
648 if (!sk1)
649 return;
650 rcu_read_lock();
651 key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
652 &ip_hdr(skb)->saddr, AF_INET);
653 if (!key)
654 goto release_sk1;
655
656 genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, NULL, skb);
657 if (genhash || memcmp(hash_location, newhash, 16) != 0)
658 goto release_sk1;
659 } else {
660 key = sk ? tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
661 &ip_hdr(skb)->saddr,
662 AF_INET) : NULL;
663 }
664
665 if (key) {
666 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
667 (TCPOPT_NOP << 16) |
668 (TCPOPT_MD5SIG << 8) |
669 TCPOLEN_MD5SIG);
670 /* Update length and the length the header thinks exists */
671 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
672 rep.th.doff = arg.iov[0].iov_len / 4;
673
674 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
675 key, ip_hdr(skb)->saddr,
676 ip_hdr(skb)->daddr, &rep.th);
677 }
678#endif
679 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
680 ip_hdr(skb)->saddr, /* XXX */
681 arg.iov[0].iov_len, IPPROTO_TCP, 0);
682 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
683 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
684 /* When socket is gone, all binding information is lost.
685 * routing might fail in this case. No choice here, if we choose to force
686 * input interface, we will misroute in case of asymmetric route.
687 */
688 if (sk)
689 arg.bound_dev_if = sk->sk_bound_dev_if;
690
691 net = dev_net(skb_dst(skb)->dev);
692 arg.tos = ip_hdr(skb)->tos;
693 ip_send_unicast_reply(net, skb, ip_hdr(skb)->saddr,
694 ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len);
695
696 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
697 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
698
699#ifdef CONFIG_TCP_MD5SIG
700release_sk1:
701 if (sk1) {
702 rcu_read_unlock();
703 sock_put(sk1);
704 }
705#endif
706}
707
708/* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
709 outside socket context is ugly, certainly. What can I do?
710 */
711
712static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
713 u32 win, u32 tsval, u32 tsecr, int oif,
714 struct tcp_md5sig_key *key,
715 int reply_flags, u8 tos)
716{
717 const struct tcphdr *th = tcp_hdr(skb);
718 struct {
719 struct tcphdr th;
720 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
721#ifdef CONFIG_TCP_MD5SIG
722 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
723#endif
724 ];
725 } rep;
726 struct ip_reply_arg arg;
727 struct net *net = dev_net(skb_dst(skb)->dev);
728
729 memset(&rep.th, 0, sizeof(struct tcphdr));
730 memset(&arg, 0, sizeof(arg));
731
732 arg.iov[0].iov_base = (unsigned char *)&rep;
733 arg.iov[0].iov_len = sizeof(rep.th);
734 if (tsecr) {
735 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
736 (TCPOPT_TIMESTAMP << 8) |
737 TCPOLEN_TIMESTAMP);
738 rep.opt[1] = htonl(tsval);
739 rep.opt[2] = htonl(tsecr);
740 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
741 }
742
743 /* Swap the send and the receive. */
744 rep.th.dest = th->source;
745 rep.th.source = th->dest;
746 rep.th.doff = arg.iov[0].iov_len / 4;
747 rep.th.seq = htonl(seq);
748 rep.th.ack_seq = htonl(ack);
749 rep.th.ack = 1;
750 rep.th.window = htons(win);
751
752#ifdef CONFIG_TCP_MD5SIG
753 if (key) {
754 int offset = (tsecr) ? 3 : 0;
755
756 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
757 (TCPOPT_NOP << 16) |
758 (TCPOPT_MD5SIG << 8) |
759 TCPOLEN_MD5SIG);
760 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
761 rep.th.doff = arg.iov[0].iov_len/4;
762
763 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
764 key, ip_hdr(skb)->saddr,
765 ip_hdr(skb)->daddr, &rep.th);
766 }
767#endif
768 arg.flags = reply_flags;
769 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
770 ip_hdr(skb)->saddr, /* XXX */
771 arg.iov[0].iov_len, IPPROTO_TCP, 0);
772 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
773 if (oif)
774 arg.bound_dev_if = oif;
775 arg.tos = tos;
776 ip_send_unicast_reply(net, skb, ip_hdr(skb)->saddr,
777 ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len);
778
779 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
780}
781
782static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
783{
784 struct inet_timewait_sock *tw = inet_twsk(sk);
785 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
786
787 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
788 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
789 tcp_time_stamp + tcptw->tw_ts_offset,
790 tcptw->tw_ts_recent,
791 tw->tw_bound_dev_if,
792 tcp_twsk_md5_key(tcptw),
793 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
794 tw->tw_tos
795 );
796
797 inet_twsk_put(tw);
798}
799
800static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
801 struct request_sock *req)
802{
803 /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
804 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
805 */
806 tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
807 tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
808 tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
809 tcp_time_stamp,
810 req->ts_recent,
811 0,
812 tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
813 AF_INET),
814 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
815 ip_hdr(skb)->tos);
816}
817
818/*
819 * Send a SYN-ACK after having received a SYN.
820 * This still operates on a request_sock only, not on a big
821 * socket.
822 */
823static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
824 struct request_sock *req,
825 u16 queue_mapping)
826{
827 const struct inet_request_sock *ireq = inet_rsk(req);
828 struct flowi4 fl4;
829 int err = -1;
830 struct sk_buff *skb;
831
832 /* First, grab a route. */
833 if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
834 return -1;
835
836 skb = tcp_make_synack(sk, dst, req, NULL);
837
838 if (skb) {
839 __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
840
841 skb_set_queue_mapping(skb, queue_mapping);
842 err = ip_build_and_send_pkt(skb, sk, ireq->ir_loc_addr,
843 ireq->ir_rmt_addr,
844 ireq->opt);
845 err = net_xmit_eval(err);
846 if (!tcp_rsk(req)->snt_synack && !err)
847 tcp_rsk(req)->snt_synack = tcp_time_stamp;
848 }
849
850 return err;
851}
852
853static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req)
854{
855 int res = tcp_v4_send_synack(sk, NULL, req, 0);
856
857 if (!res) {
858 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
859 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
860 }
861 return res;
862}
863
864/*
865 * IPv4 request_sock destructor.
866 */
867static void tcp_v4_reqsk_destructor(struct request_sock *req)
868{
869 kfree(inet_rsk(req)->opt);
870}
871
872/*
873 * Return true if a syncookie should be sent
874 */
875bool tcp_syn_flood_action(struct sock *sk,
876 const struct sk_buff *skb,
877 const char *proto)
878{
879 const char *msg = "Dropping request";
880 bool want_cookie = false;
881 struct listen_sock *lopt;
882
883#ifdef CONFIG_SYN_COOKIES
884 if (sysctl_tcp_syncookies) {
885 msg = "Sending cookies";
886 want_cookie = true;
887 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDOCOOKIES);
888 } else
889#endif
890 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
891
892 lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
893 if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {
894 lopt->synflood_warned = 1;
895 pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n",
896 proto, ntohs(tcp_hdr(skb)->dest), msg);
897 }
898 return want_cookie;
899}
900EXPORT_SYMBOL(tcp_syn_flood_action);
901
902/*
903 * Save and compile IPv4 options into the request_sock if needed.
904 */
905static struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
906{
907 const struct ip_options *opt = &(IPCB(skb)->opt);
908 struct ip_options_rcu *dopt = NULL;
909
910 if (opt && opt->optlen) {
911 int opt_size = sizeof(*dopt) + opt->optlen;
912
913 dopt = kmalloc(opt_size, GFP_ATOMIC);
914 if (dopt) {
915 if (ip_options_echo(&dopt->opt, skb)) {
916 kfree(dopt);
917 dopt = NULL;
918 }
919 }
920 }
921 return dopt;
922}
923
924#ifdef CONFIG_TCP_MD5SIG
925/*
926 * RFC2385 MD5 checksumming requires a mapping of
927 * IP address->MD5 Key.
928 * We need to maintain these in the sk structure.
929 */
930
931/* Find the Key structure for an address. */
932struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
933 const union tcp_md5_addr *addr,
934 int family)
935{
936 struct tcp_sock *tp = tcp_sk(sk);
937 struct tcp_md5sig_key *key;
938 unsigned int size = sizeof(struct in_addr);
939 struct tcp_md5sig_info *md5sig;
940
941 /* caller either holds rcu_read_lock() or socket lock */
942 md5sig = rcu_dereference_check(tp->md5sig_info,
943 sock_owned_by_user(sk) ||
944 lockdep_is_held(&sk->sk_lock.slock));
945 if (!md5sig)
946 return NULL;
947#if IS_ENABLED(CONFIG_IPV6)
948 if (family == AF_INET6)
949 size = sizeof(struct in6_addr);
950#endif
951 hlist_for_each_entry_rcu(key, &md5sig->head, node) {
952 if (key->family != family)
953 continue;
954 if (!memcmp(&key->addr, addr, size))
955 return key;
956 }
957 return NULL;
958}
959EXPORT_SYMBOL(tcp_md5_do_lookup);
960
961struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
962 struct sock *addr_sk)
963{
964 union tcp_md5_addr *addr;
965
966 addr = (union tcp_md5_addr *)&inet_sk(addr_sk)->inet_daddr;
967 return tcp_md5_do_lookup(sk, addr, AF_INET);
968}
969EXPORT_SYMBOL(tcp_v4_md5_lookup);
970
971static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
972 struct request_sock *req)
973{
974 union tcp_md5_addr *addr;
975
976 addr = (union tcp_md5_addr *)&inet_rsk(req)->ir_rmt_addr;
977 return tcp_md5_do_lookup(sk, addr, AF_INET);
978}
979
980/* This can be called on a newly created socket, from other files */
981int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
982 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
983{
984 /* Add Key to the list */
985 struct tcp_md5sig_key *key;
986 struct tcp_sock *tp = tcp_sk(sk);
987 struct tcp_md5sig_info *md5sig;
988
989 key = tcp_md5_do_lookup(sk, addr, family);
990 if (key) {
991 /* Pre-existing entry - just update that one. */
992 memcpy(key->key, newkey, newkeylen);
993 key->keylen = newkeylen;
994 return 0;
995 }
996
997 md5sig = rcu_dereference_protected(tp->md5sig_info,
998 sock_owned_by_user(sk));
999 if (!md5sig) {
1000 md5sig = kmalloc(sizeof(*md5sig), gfp);
1001 if (!md5sig)
1002 return -ENOMEM;
1003
1004 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
1005 INIT_HLIST_HEAD(&md5sig->head);
1006 rcu_assign_pointer(tp->md5sig_info, md5sig);
1007 }
1008
1009 key = sock_kmalloc(sk, sizeof(*key), gfp);
1010 if (!key)
1011 return -ENOMEM;
1012 if (!tcp_alloc_md5sig_pool()) {
1013 sock_kfree_s(sk, key, sizeof(*key));
1014 return -ENOMEM;
1015 }
1016
1017 memcpy(key->key, newkey, newkeylen);
1018 key->keylen = newkeylen;
1019 key->family = family;
1020 memcpy(&key->addr, addr,
1021 (family == AF_INET6) ? sizeof(struct in6_addr) :
1022 sizeof(struct in_addr));
1023 hlist_add_head_rcu(&key->node, &md5sig->head);
1024 return 0;
1025}
1026EXPORT_SYMBOL(tcp_md5_do_add);
1027
1028int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
1029{
1030 struct tcp_md5sig_key *key;
1031
1032 key = tcp_md5_do_lookup(sk, addr, family);
1033 if (!key)
1034 return -ENOENT;
1035 hlist_del_rcu(&key->node);
1036 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
1037 kfree_rcu(key, rcu);
1038 return 0;
1039}
1040EXPORT_SYMBOL(tcp_md5_do_del);
1041
1042static void tcp_clear_md5_list(struct sock *sk)
1043{
1044 struct tcp_sock *tp = tcp_sk(sk);
1045 struct tcp_md5sig_key *key;
1046 struct hlist_node *n;
1047 struct tcp_md5sig_info *md5sig;
1048
1049 md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
1050
1051 hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
1052 hlist_del_rcu(&key->node);
1053 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
1054 kfree_rcu(key, rcu);
1055 }
1056}
1057
1058static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
1059 int optlen)
1060{
1061 struct tcp_md5sig cmd;
1062 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
1063
1064 if (optlen < sizeof(cmd))
1065 return -EINVAL;
1066
1067 if (copy_from_user(&cmd, optval, sizeof(cmd)))
1068 return -EFAULT;
1069
1070 if (sin->sin_family != AF_INET)
1071 return -EINVAL;
1072
1073 if (!cmd.tcpm_key || !cmd.tcpm_keylen)
1074 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1075 AF_INET);
1076
1077 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1078 return -EINVAL;
1079
1080 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1081 AF_INET, cmd.tcpm_key, cmd.tcpm_keylen,
1082 GFP_KERNEL);
1083}
1084
1085static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1086 __be32 daddr, __be32 saddr, int nbytes)
1087{
1088 struct tcp4_pseudohdr *bp;
1089 struct scatterlist sg;
1090
1091 bp = &hp->md5_blk.ip4;
1092
1093 /*
1094 * 1. the TCP pseudo-header (in the order: source IP address,
1095 * destination IP address, zero-padded protocol number, and
1096 * segment length)
1097 */
1098 bp->saddr = saddr;
1099 bp->daddr = daddr;
1100 bp->pad = 0;
1101 bp->protocol = IPPROTO_TCP;
1102 bp->len = cpu_to_be16(nbytes);
1103
1104 sg_init_one(&sg, bp, sizeof(*bp));
1105 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1106}
1107
1108static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
1109 __be32 daddr, __be32 saddr, const struct tcphdr *th)
1110{
1111 struct tcp_md5sig_pool *hp;
1112 struct hash_desc *desc;
1113
1114 hp = tcp_get_md5sig_pool();
1115 if (!hp)
1116 goto clear_hash_noput;
1117 desc = &hp->md5_desc;
1118
1119 if (crypto_hash_init(desc))
1120 goto clear_hash;
1121 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1122 goto clear_hash;
1123 if (tcp_md5_hash_header(hp, th))
1124 goto clear_hash;
1125 if (tcp_md5_hash_key(hp, key))
1126 goto clear_hash;
1127 if (crypto_hash_final(desc, md5_hash))
1128 goto clear_hash;
1129
1130 tcp_put_md5sig_pool();
1131 return 0;
1132
1133clear_hash:
1134 tcp_put_md5sig_pool();
1135clear_hash_noput:
1136 memset(md5_hash, 0, 16);
1137 return 1;
1138}
1139
1140int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1141 const struct sock *sk, const struct request_sock *req,
1142 const struct sk_buff *skb)
1143{
1144 struct tcp_md5sig_pool *hp;
1145 struct hash_desc *desc;
1146 const struct tcphdr *th = tcp_hdr(skb);
1147 __be32 saddr, daddr;
1148
1149 if (sk) {
1150 saddr = inet_sk(sk)->inet_saddr;
1151 daddr = inet_sk(sk)->inet_daddr;
1152 } else if (req) {
1153 saddr = inet_rsk(req)->ir_loc_addr;
1154 daddr = inet_rsk(req)->ir_rmt_addr;
1155 } else {
1156 const struct iphdr *iph = ip_hdr(skb);
1157 saddr = iph->saddr;
1158 daddr = iph->daddr;
1159 }
1160
1161 hp = tcp_get_md5sig_pool();
1162 if (!hp)
1163 goto clear_hash_noput;
1164 desc = &hp->md5_desc;
1165
1166 if (crypto_hash_init(desc))
1167 goto clear_hash;
1168
1169 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1170 goto clear_hash;
1171 if (tcp_md5_hash_header(hp, th))
1172 goto clear_hash;
1173 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1174 goto clear_hash;
1175 if (tcp_md5_hash_key(hp, key))
1176 goto clear_hash;
1177 if (crypto_hash_final(desc, md5_hash))
1178 goto clear_hash;
1179
1180 tcp_put_md5sig_pool();
1181 return 0;
1182
1183clear_hash:
1184 tcp_put_md5sig_pool();
1185clear_hash_noput:
1186 memset(md5_hash, 0, 16);
1187 return 1;
1188}
1189EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1190
1191static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
1192{
1193 /*
1194 * This gets called for each TCP segment that arrives
1195 * so we want to be efficient.
1196 * We have 3 drop cases:
1197 * o No MD5 hash and one expected.
1198 * o MD5 hash and we're not expecting one.
1199 * o MD5 hash and its wrong.
1200 */
1201 const __u8 *hash_location = NULL;
1202 struct tcp_md5sig_key *hash_expected;
1203 const struct iphdr *iph = ip_hdr(skb);
1204 const struct tcphdr *th = tcp_hdr(skb);
1205 int genhash;
1206 unsigned char newhash[16];
1207
1208 hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr,
1209 AF_INET);
1210 hash_location = tcp_parse_md5sig_option(th);
1211
1212 /* We've parsed the options - do we have a hash? */
1213 if (!hash_expected && !hash_location)
1214 return false;
1215
1216 if (hash_expected && !hash_location) {
1217 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1218 return true;
1219 }
1220
1221 if (!hash_expected && hash_location) {
1222 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1223 return true;
1224 }
1225
1226 /* Okay, so this is hash_expected and hash_location -
1227 * so we need to calculate the checksum.
1228 */
1229 genhash = tcp_v4_md5_hash_skb(newhash,
1230 hash_expected,
1231 NULL, NULL, skb);
1232
1233 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1234 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1235 &iph->saddr, ntohs(th->source),
1236 &iph->daddr, ntohs(th->dest),
1237 genhash ? " tcp_v4_calc_md5_hash failed"
1238 : "");
1239 return true;
1240 }
1241 return false;
1242}
1243
1244#endif
1245
1246struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1247 .family = PF_INET,
1248 .obj_size = sizeof(struct tcp_request_sock),
1249 .rtx_syn_ack = tcp_v4_rtx_synack,
1250 .send_ack = tcp_v4_reqsk_send_ack,
1251 .destructor = tcp_v4_reqsk_destructor,
1252 .send_reset = tcp_v4_send_reset,
1253 .syn_ack_timeout = tcp_syn_ack_timeout,
1254};
1255
1256#ifdef CONFIG_TCP_MD5SIG
1257static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1258 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1259 .calc_md5_hash = tcp_v4_md5_hash_skb,
1260};
1261#endif
1262
1263static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
1264 struct request_sock *req,
1265 struct tcp_fastopen_cookie *foc,
1266 struct tcp_fastopen_cookie *valid_foc)
1267{
1268 bool skip_cookie = false;
1269 struct fastopen_queue *fastopenq;
1270
1271 if (likely(!fastopen_cookie_present(foc))) {
1272 /* See include/net/tcp.h for the meaning of these knobs */
1273 if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
1274 ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
1275 (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
1276 skip_cookie = true; /* no cookie to validate */
1277 else
1278 return false;
1279 }
1280 fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
1281 /* A FO option is present; bump the counter. */
1282 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
1283
1284 /* Make sure the listener has enabled fastopen, and we don't
1285 * exceed the max # of pending TFO requests allowed before trying
1286 * to validating the cookie in order to avoid burning CPU cycles
1287 * unnecessarily.
1288 *
1289 * XXX (TFO) - The implication of checking the max_qlen before
1290 * processing a cookie request is that clients can't differentiate
1291 * between qlen overflow causing Fast Open to be disabled
1292 * temporarily vs a server not supporting Fast Open at all.
1293 */
1294 if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
1295 fastopenq == NULL || fastopenq->max_qlen == 0)
1296 return false;
1297
1298 if (fastopenq->qlen >= fastopenq->max_qlen) {
1299 struct request_sock *req1;
1300 spin_lock(&fastopenq->lock);
1301 req1 = fastopenq->rskq_rst_head;
1302 if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
1303 spin_unlock(&fastopenq->lock);
1304 NET_INC_STATS_BH(sock_net(sk),
1305 LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
1306 /* Avoid bumping LINUX_MIB_TCPFASTOPENPASSIVEFAIL*/
1307 foc->len = -1;
1308 return false;
1309 }
1310 fastopenq->rskq_rst_head = req1->dl_next;
1311 fastopenq->qlen--;
1312 spin_unlock(&fastopenq->lock);
1313 reqsk_free(req1);
1314 }
1315 if (skip_cookie) {
1316 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1317 return true;
1318 }
1319
1320 if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
1321 if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
1322 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
1323 ip_hdr(skb)->daddr, valid_foc);
1324 if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
1325 memcmp(&foc->val[0], &valid_foc->val[0],
1326 TCP_FASTOPEN_COOKIE_SIZE) != 0)
1327 return false;
1328 valid_foc->len = -1;
1329 }
1330 /* Acknowledge the data received from the peer. */
1331 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1332 return true;
1333 } else if (foc->len == 0) { /* Client requesting a cookie */
1334 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
1335 ip_hdr(skb)->daddr, valid_foc);
1336 NET_INC_STATS_BH(sock_net(sk),
1337 LINUX_MIB_TCPFASTOPENCOOKIEREQD);
1338 } else {
1339 /* Client sent a cookie with wrong size. Treat it
1340 * the same as invalid and return a valid one.
1341 */
1342 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
1343 ip_hdr(skb)->daddr, valid_foc);
1344 }
1345 return false;
1346}
1347
1348static int tcp_v4_conn_req_fastopen(struct sock *sk,
1349 struct sk_buff *skb,
1350 struct sk_buff *skb_synack,
1351 struct request_sock *req)
1352{
1353 struct tcp_sock *tp = tcp_sk(sk);
1354 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1355 const struct inet_request_sock *ireq = inet_rsk(req);
1356 struct sock *child;
1357 int err;
1358
1359 req->num_retrans = 0;
1360 req->num_timeout = 0;
1361 req->sk = NULL;
1362
1363 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
1364 if (child == NULL) {
1365 NET_INC_STATS_BH(sock_net(sk),
1366 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
1367 kfree_skb(skb_synack);
1368 return -1;
1369 }
1370 err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
1371 ireq->ir_rmt_addr, ireq->opt);
1372 err = net_xmit_eval(err);
1373 if (!err)
1374 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1375 /* XXX (TFO) - is it ok to ignore error and continue? */
1376
1377 spin_lock(&queue->fastopenq->lock);
1378 queue->fastopenq->qlen++;
1379 spin_unlock(&queue->fastopenq->lock);
1380
1381 /* Initialize the child socket. Have to fix some values to take
1382 * into account the child is a Fast Open socket and is created
1383 * only out of the bits carried in the SYN packet.
1384 */
1385 tp = tcp_sk(child);
1386
1387 tp->fastopen_rsk = req;
1388 /* Do a hold on the listner sk so that if the listener is being
1389 * closed, the child that has been accepted can live on and still
1390 * access listen_lock.
1391 */
1392 sock_hold(sk);
1393 tcp_rsk(req)->listener = sk;
1394
1395 /* RFC1323: The window in SYN & SYN/ACK segments is never
1396 * scaled. So correct it appropriately.
1397 */
1398 tp->snd_wnd = ntohs(tcp_hdr(skb)->window);
1399
1400 /* Activate the retrans timer so that SYNACK can be retransmitted.
1401 * The request socket is not added to the SYN table of the parent
1402 * because it's been added to the accept queue directly.
1403 */
1404 inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
1405 TCP_TIMEOUT_INIT, TCP_RTO_MAX);
1406
1407 /* Add the child socket directly into the accept queue */
1408 inet_csk_reqsk_queue_add(sk, req, child);
1409
1410 /* Now finish processing the fastopen child socket. */
1411 inet_csk(child)->icsk_af_ops->rebuild_header(child);
1412 tcp_init_congestion_control(child);
1413 tcp_mtup_init(child);
1414 tcp_init_metrics(child);
1415 tcp_init_buffer_space(child);
1416
1417 /* Queue the data carried in the SYN packet. We need to first
1418 * bump skb's refcnt because the caller will attempt to free it.
1419 *
1420 * XXX (TFO) - we honor a zero-payload TFO request for now.
1421 * (Any reason not to?)
1422 */
1423 if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
1424 /* Don't queue the skb if there is no payload in SYN.
1425 * XXX (TFO) - How about SYN+FIN?
1426 */
1427 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1428 } else {
1429 skb = skb_get(skb);
1430 skb_dst_drop(skb);
1431 __skb_pull(skb, tcp_hdr(skb)->doff * 4);
1432 skb_set_owner_r(skb, child);
1433 __skb_queue_tail(&child->sk_receive_queue, skb);
1434 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1435 tp->syn_data_acked = 1;
1436 }
1437 sk->sk_data_ready(sk);
1438 bh_unlock_sock(child);
1439 sock_put(child);
1440 WARN_ON(req->sk == NULL);
1441 return 0;
1442}
1443
1444int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1445{
1446 struct tcp_options_received tmp_opt;
1447 struct request_sock *req;
1448 struct inet_request_sock *ireq;
1449 struct tcp_sock *tp = tcp_sk(sk);
1450 struct dst_entry *dst = NULL;
1451 __be32 saddr = ip_hdr(skb)->saddr;
1452 __be32 daddr = ip_hdr(skb)->daddr;
1453 __u32 isn = TCP_SKB_CB(skb)->when;
1454 bool want_cookie = false;
1455 struct flowi4 fl4;
1456 struct tcp_fastopen_cookie foc = { .len = -1 };
1457 struct tcp_fastopen_cookie valid_foc = { .len = -1 };
1458 struct sk_buff *skb_synack;
1459 int do_fastopen;
1460
1461 /* Never answer to SYNs send to broadcast or multicast */
1462 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1463 goto drop;
1464
1465 /* TW buckets are converted to open requests without
1466 * limitations, they conserve resources and peer is
1467 * evidently real one.
1468 */
1469 if ((sysctl_tcp_syncookies == 2 ||
1470 inet_csk_reqsk_queue_is_full(sk)) && !isn) {
1471 want_cookie = tcp_syn_flood_action(sk, skb, "TCP");
1472 if (!want_cookie)
1473 goto drop;
1474 }
1475
1476 /* Accept backlog is full. If we have already queued enough
1477 * of warm entries in syn queue, drop request. It is better than
1478 * clogging syn queue with openreqs with exponentially increasing
1479 * timeout.
1480 */
1481 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
1482 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1483 goto drop;
1484 }
1485
1486 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1487 if (!req)
1488 goto drop;
1489
1490#ifdef CONFIG_TCP_MD5SIG
1491 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1492#endif
1493
1494 tcp_clear_options(&tmp_opt);
1495 tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
1496 tmp_opt.user_mss = tp->rx_opt.user_mss;
1497 tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
1498
1499 if (want_cookie && !tmp_opt.saw_tstamp)
1500 tcp_clear_options(&tmp_opt);
1501
1502 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1503 tcp_openreq_init(req, &tmp_opt, skb);
1504
1505 ireq = inet_rsk(req);
1506 ireq->ir_loc_addr = daddr;
1507 ireq->ir_rmt_addr = saddr;
1508 ireq->no_srccheck = inet_sk(sk)->transparent;
1509 ireq->opt = tcp_v4_save_options(skb);
1510
1511 if (security_inet_conn_request(sk, skb, req))
1512 goto drop_and_free;
1513
1514 if (!want_cookie || tmp_opt.tstamp_ok)
1515 TCP_ECN_create_request(req, skb, sock_net(sk));
1516
1517 if (want_cookie) {
1518 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1519 req->cookie_ts = tmp_opt.tstamp_ok;
1520 } else if (!isn) {
1521 /* VJ's idea. We save last timestamp seen
1522 * from the destination in peer table, when entering
1523 * state TIME-WAIT, and check against it before
1524 * accepting new connection request.
1525 *
1526 * If "isn" is not zero, this request hit alive
1527 * timewait bucket, so that all the necessary checks
1528 * are made in the function processing timewait state.
1529 */
1530 if (tmp_opt.saw_tstamp &&
1531 tcp_death_row.sysctl_tw_recycle &&
1532 (dst = inet_csk_route_req(sk, &fl4, req)) != NULL &&
1533 fl4.daddr == saddr) {
1534 if (!tcp_peer_is_proven(req, dst, true)) {
1535 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1536 goto drop_and_release;
1537 }
1538 }
1539 /* Kill the following clause, if you dislike this way. */
1540 else if (!sysctl_tcp_syncookies &&
1541 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1542 (sysctl_max_syn_backlog >> 2)) &&
1543 !tcp_peer_is_proven(req, dst, false)) {
1544 /* Without syncookies last quarter of
1545 * backlog is filled with destinations,
1546 * proven to be alive.
1547 * It means that we continue to communicate
1548 * to destinations, already remembered
1549 * to the moment of synflood.
1550 */
1551 LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
1552 &saddr, ntohs(tcp_hdr(skb)->source));
1553 goto drop_and_release;
1554 }
1555
1556 isn = tcp_v4_init_sequence(skb);
1557 }
1558 tcp_rsk(req)->snt_isn = isn;
1559
1560 if (dst == NULL) {
1561 dst = inet_csk_route_req(sk, &fl4, req);
1562 if (dst == NULL)
1563 goto drop_and_free;
1564 }
1565 do_fastopen = tcp_fastopen_check(sk, skb, req, &foc, &valid_foc);
1566
1567 /* We don't call tcp_v4_send_synack() directly because we need
1568 * to make sure a child socket can be created successfully before
1569 * sending back synack!
1570 *
1571 * XXX (TFO) - Ideally one would simply call tcp_v4_send_synack()
1572 * (or better yet, call tcp_send_synack() in the child context
1573 * directly, but will have to fix bunch of other code first)
1574 * after syn_recv_sock() except one will need to first fix the
1575 * latter to remove its dependency on the current implementation
1576 * of tcp_v4_send_synack()->tcp_select_initial_window().
1577 */
1578 skb_synack = tcp_make_synack(sk, dst, req,
1579 fastopen_cookie_present(&valid_foc) ? &valid_foc : NULL);
1580
1581 if (skb_synack) {
1582 __tcp_v4_send_check(skb_synack, ireq->ir_loc_addr, ireq->ir_rmt_addr);
1583 skb_set_queue_mapping(skb_synack, skb_get_queue_mapping(skb));
1584 } else
1585 goto drop_and_free;
1586
1587 if (likely(!do_fastopen)) {
1588 int err;
1589 err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
1590 ireq->ir_rmt_addr, ireq->opt);
1591 err = net_xmit_eval(err);
1592 if (err || want_cookie)
1593 goto drop_and_free;
1594
1595 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1596 tcp_rsk(req)->listener = NULL;
1597 /* Add the request_sock to the SYN table */
1598 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1599 if (fastopen_cookie_present(&foc) && foc.len != 0)
1600 NET_INC_STATS_BH(sock_net(sk),
1601 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
1602 } else if (tcp_v4_conn_req_fastopen(sk, skb, skb_synack, req))
1603 goto drop_and_free;
1604
1605 return 0;
1606
1607drop_and_release:
1608 dst_release(dst);
1609drop_and_free:
1610 reqsk_free(req);
1611drop:
1612 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1613 return 0;
1614}
1615EXPORT_SYMBOL(tcp_v4_conn_request);
1616
1617
1618/*
1619 * The three way handshake has completed - we got a valid synack -
1620 * now create the new socket.
1621 */
1622struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1623 struct request_sock *req,
1624 struct dst_entry *dst)
1625{
1626 struct inet_request_sock *ireq;
1627 struct inet_sock *newinet;
1628 struct tcp_sock *newtp;
1629 struct sock *newsk;
1630#ifdef CONFIG_TCP_MD5SIG
1631 struct tcp_md5sig_key *key;
1632#endif
1633 struct ip_options_rcu *inet_opt;
1634
1635 if (sk_acceptq_is_full(sk))
1636 goto exit_overflow;
1637
1638 newsk = tcp_create_openreq_child(sk, req, skb);
1639 if (!newsk)
1640 goto exit_nonewsk;
1641
1642 newsk->sk_gso_type = SKB_GSO_TCPV4;
1643 inet_sk_rx_dst_set(newsk, skb);
1644
1645 newtp = tcp_sk(newsk);
1646 newinet = inet_sk(newsk);
1647 ireq = inet_rsk(req);
1648 newinet->inet_daddr = ireq->ir_rmt_addr;
1649 newinet->inet_rcv_saddr = ireq->ir_loc_addr;
1650 newinet->inet_saddr = ireq->ir_loc_addr;
1651 inet_opt = ireq->opt;
1652 rcu_assign_pointer(newinet->inet_opt, inet_opt);
1653 ireq->opt = NULL;
1654 newinet->mc_index = inet_iif(skb);
1655 newinet->mc_ttl = ip_hdr(skb)->ttl;
1656 newinet->rcv_tos = ip_hdr(skb)->tos;
1657 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1658 if (inet_opt)
1659 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
1660 newinet->inet_id = newtp->write_seq ^ jiffies;
1661
1662 if (!dst) {
1663 dst = inet_csk_route_child_sock(sk, newsk, req);
1664 if (!dst)
1665 goto put_and_exit;
1666 } else {
1667 /* syncookie case : see end of cookie_v4_check() */
1668 }
1669 sk_setup_caps(newsk, dst);
1670
1671 tcp_sync_mss(newsk, dst_mtu(dst));
1672 newtp->advmss = dst_metric_advmss(dst);
1673 if (tcp_sk(sk)->rx_opt.user_mss &&
1674 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1675 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1676
1677 tcp_initialize_rcv_mss(newsk);
1678
1679#ifdef CONFIG_TCP_MD5SIG
1680 /* Copy over the MD5 key from the original socket */
1681 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr,
1682 AF_INET);
1683 if (key != NULL) {
1684 /*
1685 * We're using one, so create a matching key
1686 * on the newsk structure. If we fail to get
1687 * memory, then we end up not copying the key
1688 * across. Shucks.
1689 */
1690 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr,
1691 AF_INET, key->key, key->keylen, GFP_ATOMIC);
1692 sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1693 }
1694#endif
1695
1696 if (__inet_inherit_port(sk, newsk) < 0)
1697 goto put_and_exit;
1698 __inet_hash_nolisten(newsk, NULL);
1699
1700 return newsk;
1701
1702exit_overflow:
1703 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1704exit_nonewsk:
1705 dst_release(dst);
1706exit:
1707 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1708 return NULL;
1709put_and_exit:
1710 inet_csk_prepare_forced_close(newsk);
1711 tcp_done(newsk);
1712 goto exit;
1713}
1714EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1715
1716static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1717{
1718 struct tcphdr *th = tcp_hdr(skb);
1719 const struct iphdr *iph = ip_hdr(skb);
1720 struct sock *nsk;
1721 struct request_sock **prev;
1722 /* Find possible connection requests. */
1723 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1724 iph->saddr, iph->daddr);
1725 if (req)
1726 return tcp_check_req(sk, skb, req, prev, false);
1727
1728 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1729 th->source, iph->daddr, th->dest, inet_iif(skb));
1730
1731 if (nsk) {
1732 if (nsk->sk_state != TCP_TIME_WAIT) {
1733 bh_lock_sock(nsk);
1734 return nsk;
1735 }
1736 inet_twsk_put(inet_twsk(nsk));
1737 return NULL;
1738 }
1739
1740#ifdef CONFIG_SYN_COOKIES
1741 if (!th->syn)
1742 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1743#endif
1744 return sk;
1745}
1746
1747static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1748{
1749 const struct iphdr *iph = ip_hdr(skb);
1750
1751 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1752 if (!tcp_v4_check(skb->len, iph->saddr,
1753 iph->daddr, skb->csum)) {
1754 skb->ip_summed = CHECKSUM_UNNECESSARY;
1755 return 0;
1756 }
1757 }
1758
1759 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1760 skb->len, IPPROTO_TCP, 0);
1761
1762 if (skb->len <= 76) {
1763 return __skb_checksum_complete(skb);
1764 }
1765 return 0;
1766}
1767
1768
1769/* The socket must have it's spinlock held when we get
1770 * here.
1771 *
1772 * We have a potential double-lock case here, so even when
1773 * doing backlog processing we use the BH locking scheme.
1774 * This is because we cannot sleep with the original spinlock
1775 * held.
1776 */
1777int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1778{
1779 struct sock *rsk;
1780#ifdef CONFIG_TCP_MD5SIG
1781 /*
1782 * We really want to reject the packet as early as possible
1783 * if:
1784 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1785 * o There is an MD5 option and we're not expecting one
1786 */
1787 if (tcp_v4_inbound_md5_hash(sk, skb))
1788 goto discard;
1789#endif
1790
1791 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1792 struct dst_entry *dst = sk->sk_rx_dst;
1793
1794 sock_rps_save_rxhash(sk, skb);
1795 if (dst) {
1796 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
1797 dst->ops->check(dst, 0) == NULL) {
1798 dst_release(dst);
1799 sk->sk_rx_dst = NULL;
1800 }
1801 }
1802 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
1803 return 0;
1804 }
1805
1806 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1807 goto csum_err;
1808
1809 if (sk->sk_state == TCP_LISTEN) {
1810 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1811 if (!nsk)
1812 goto discard;
1813
1814 if (nsk != sk) {
1815 sock_rps_save_rxhash(nsk, skb);
1816 if (tcp_child_process(sk, nsk, skb)) {
1817 rsk = nsk;
1818 goto reset;
1819 }
1820 return 0;
1821 }
1822 } else
1823 sock_rps_save_rxhash(sk, skb);
1824
1825 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1826 rsk = sk;
1827 goto reset;
1828 }
1829 return 0;
1830
1831reset:
1832 tcp_v4_send_reset(rsk, skb);
1833discard:
1834 kfree_skb(skb);
1835 /* Be careful here. If this function gets more complicated and
1836 * gcc suffers from register pressure on the x86, sk (in %ebx)
1837 * might be destroyed here. This current version compiles correctly,
1838 * but you have been warned.
1839 */
1840 return 0;
1841
1842csum_err:
1843 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
1844 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1845 goto discard;
1846}
1847EXPORT_SYMBOL(tcp_v4_do_rcv);
1848
1849void tcp_v4_early_demux(struct sk_buff *skb)
1850{
1851 const struct iphdr *iph;
1852 const struct tcphdr *th;
1853 struct sock *sk;
1854
1855 if (skb->pkt_type != PACKET_HOST)
1856 return;
1857
1858 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
1859 return;
1860
1861 iph = ip_hdr(skb);
1862 th = tcp_hdr(skb);
1863
1864 if (th->doff < sizeof(struct tcphdr) / 4)
1865 return;
1866
1867 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
1868 iph->saddr, th->source,
1869 iph->daddr, ntohs(th->dest),
1870 skb->skb_iif);
1871 if (sk) {
1872 skb->sk = sk;
1873 skb->destructor = sock_edemux;
1874 if (sk->sk_state != TCP_TIME_WAIT) {
1875 struct dst_entry *dst = sk->sk_rx_dst;
1876
1877 if (dst)
1878 dst = dst_check(dst, 0);
1879 if (dst &&
1880 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
1881 skb_dst_set_noref(skb, dst);
1882 }
1883 }
1884}
1885
1886/* Packet is added to VJ-style prequeue for processing in process
1887 * context, if a reader task is waiting. Apparently, this exciting
1888 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1889 * failed somewhere. Latency? Burstiness? Well, at least now we will
1890 * see, why it failed. 8)8) --ANK
1891 *
1892 */
1893bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1894{
1895 struct tcp_sock *tp = tcp_sk(sk);
1896
1897 if (sysctl_tcp_low_latency || !tp->ucopy.task)
1898 return false;
1899
1900 if (skb->len <= tcp_hdrlen(skb) &&
1901 skb_queue_len(&tp->ucopy.prequeue) == 0)
1902 return false;
1903
1904 skb_dst_force(skb);
1905 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1906 tp->ucopy.memory += skb->truesize;
1907 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1908 struct sk_buff *skb1;
1909
1910 BUG_ON(sock_owned_by_user(sk));
1911
1912 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1913 sk_backlog_rcv(sk, skb1);
1914 NET_INC_STATS_BH(sock_net(sk),
1915 LINUX_MIB_TCPPREQUEUEDROPPED);
1916 }
1917
1918 tp->ucopy.memory = 0;
1919 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1920 wake_up_interruptible_sync_poll(sk_sleep(sk),
1921 POLLIN | POLLRDNORM | POLLRDBAND);
1922 if (!inet_csk_ack_scheduled(sk))
1923 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1924 (3 * tcp_rto_min(sk)) / 4,
1925 TCP_RTO_MAX);
1926 }
1927 return true;
1928}
1929EXPORT_SYMBOL(tcp_prequeue);
1930
1931/*
1932 * From tcp_input.c
1933 */
1934
1935int tcp_v4_rcv(struct sk_buff *skb)
1936{
1937 const struct iphdr *iph;
1938 const struct tcphdr *th;
1939 struct sock *sk;
1940 int ret;
1941 struct net *net = dev_net(skb->dev);
1942
1943 if (skb->pkt_type != PACKET_HOST)
1944 goto discard_it;
1945
1946 /* Count it even if it's bad */
1947 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1948
1949 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1950 goto discard_it;
1951
1952 th = tcp_hdr(skb);
1953
1954 if (th->doff < sizeof(struct tcphdr) / 4)
1955 goto bad_packet;
1956 if (!pskb_may_pull(skb, th->doff * 4))
1957 goto discard_it;
1958
1959 /* An explanation is required here, I think.
1960 * Packet length and doff are validated by header prediction,
1961 * provided case of th->doff==0 is eliminated.
1962 * So, we defer the checks. */
1963 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1964 goto csum_error;
1965
1966 th = tcp_hdr(skb);
1967 iph = ip_hdr(skb);
1968 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1969 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1970 skb->len - th->doff * 4);
1971 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1972 TCP_SKB_CB(skb)->when = 0;
1973 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
1974 TCP_SKB_CB(skb)->sacked = 0;
1975
1976 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1977 if (!sk)
1978 goto no_tcp_socket;
1979
1980process:
1981 if (sk->sk_state == TCP_TIME_WAIT)
1982 goto do_time_wait;
1983
1984 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
1985 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1986 goto discard_and_relse;
1987 }
1988
1989 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1990 goto discard_and_relse;
1991 nf_reset(skb);
1992
1993 if (sk_filter(sk, skb))
1994 goto discard_and_relse;
1995
1996 sk_mark_napi_id(sk, skb);
1997 skb->dev = NULL;
1998
1999 bh_lock_sock_nested(sk);
2000 ret = 0;
2001 if (!sock_owned_by_user(sk)) {
2002#ifdef CONFIG_NET_DMA
2003 struct tcp_sock *tp = tcp_sk(sk);
2004 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
2005 tp->ucopy.dma_chan = net_dma_find_channel();
2006 if (tp->ucopy.dma_chan)
2007 ret = tcp_v4_do_rcv(sk, skb);
2008 else
2009#endif
2010 {
2011 if (!tcp_prequeue(sk, skb))
2012 ret = tcp_v4_do_rcv(sk, skb);
2013 }
2014 } else if (unlikely(sk_add_backlog(sk, skb,
2015 sk->sk_rcvbuf + sk->sk_sndbuf))) {
2016 bh_unlock_sock(sk);
2017 NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
2018 goto discard_and_relse;
2019 }
2020 bh_unlock_sock(sk);
2021
2022 sock_put(sk);
2023
2024 return ret;
2025
2026no_tcp_socket:
2027 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
2028 goto discard_it;
2029
2030 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
2031csum_error:
2032 TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
2033bad_packet:
2034 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
2035 } else {
2036 tcp_v4_send_reset(NULL, skb);
2037 }
2038
2039discard_it:
2040 /* Discard frame. */
2041 kfree_skb(skb);
2042 return 0;
2043
2044discard_and_relse:
2045 sock_put(sk);
2046 goto discard_it;
2047
2048do_time_wait:
2049 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
2050 inet_twsk_put(inet_twsk(sk));
2051 goto discard_it;
2052 }
2053
2054 if (skb->len < (th->doff << 2)) {
2055 inet_twsk_put(inet_twsk(sk));
2056 goto bad_packet;
2057 }
2058 if (tcp_checksum_complete(skb)) {
2059 inet_twsk_put(inet_twsk(sk));
2060 goto csum_error;
2061 }
2062 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
2063 case TCP_TW_SYN: {
2064 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
2065 &tcp_hashinfo,
2066 iph->saddr, th->source,
2067 iph->daddr, th->dest,
2068 inet_iif(skb));
2069 if (sk2) {
2070 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
2071 inet_twsk_put(inet_twsk(sk));
2072 sk = sk2;
2073 goto process;
2074 }
2075 /* Fall through to ACK */
2076 }
2077 case TCP_TW_ACK:
2078 tcp_v4_timewait_ack(sk, skb);
2079 break;
2080 case TCP_TW_RST:
2081 goto no_tcp_socket;
2082 case TCP_TW_SUCCESS:;
2083 }
2084 goto discard_it;
2085}
2086
2087static struct timewait_sock_ops tcp_timewait_sock_ops = {
2088 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
2089 .twsk_unique = tcp_twsk_unique,
2090 .twsk_destructor= tcp_twsk_destructor,
2091};
2092
2093void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
2094{
2095 struct dst_entry *dst = skb_dst(skb);
2096
2097 dst_hold(dst);
2098 sk->sk_rx_dst = dst;
2099 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
2100}
2101EXPORT_SYMBOL(inet_sk_rx_dst_set);
2102
2103const struct inet_connection_sock_af_ops ipv4_specific = {
2104 .queue_xmit = ip_queue_xmit,
2105 .send_check = tcp_v4_send_check,
2106 .rebuild_header = inet_sk_rebuild_header,
2107 .sk_rx_dst_set = inet_sk_rx_dst_set,
2108 .conn_request = tcp_v4_conn_request,
2109 .syn_recv_sock = tcp_v4_syn_recv_sock,
2110 .net_header_len = sizeof(struct iphdr),
2111 .setsockopt = ip_setsockopt,
2112 .getsockopt = ip_getsockopt,
2113 .addr2sockaddr = inet_csk_addr2sockaddr,
2114 .sockaddr_len = sizeof(struct sockaddr_in),
2115 .bind_conflict = inet_csk_bind_conflict,
2116#ifdef CONFIG_COMPAT
2117 .compat_setsockopt = compat_ip_setsockopt,
2118 .compat_getsockopt = compat_ip_getsockopt,
2119#endif
2120};
2121EXPORT_SYMBOL(ipv4_specific);
2122
2123#ifdef CONFIG_TCP_MD5SIG
2124static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
2125 .md5_lookup = tcp_v4_md5_lookup,
2126 .calc_md5_hash = tcp_v4_md5_hash_skb,
2127 .md5_parse = tcp_v4_parse_md5_keys,
2128};
2129#endif
2130
2131/* NOTE: A lot of things set to zero explicitly by call to
2132 * sk_alloc() so need not be done here.
2133 */
2134static int tcp_v4_init_sock(struct sock *sk)
2135{
2136 struct inet_connection_sock *icsk = inet_csk(sk);
2137
2138 tcp_init_sock(sk);
2139
2140 icsk->icsk_af_ops = &ipv4_specific;
2141
2142#ifdef CONFIG_TCP_MD5SIG
2143 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
2144#endif
2145
2146 return 0;
2147}
2148
2149void tcp_v4_destroy_sock(struct sock *sk)
2150{
2151 struct tcp_sock *tp = tcp_sk(sk);
2152
2153 tcp_clear_xmit_timers(sk);
2154
2155 tcp_cleanup_congestion_control(sk);
2156
2157 /* Cleanup up the write buffer. */
2158 tcp_write_queue_purge(sk);
2159
2160 /* Cleans up our, hopefully empty, out_of_order_queue. */
2161 __skb_queue_purge(&tp->out_of_order_queue);
2162
2163#ifdef CONFIG_TCP_MD5SIG
2164 /* Clean up the MD5 key list, if any */
2165 if (tp->md5sig_info) {
2166 tcp_clear_md5_list(sk);
2167 kfree_rcu(tp->md5sig_info, rcu);
2168 tp->md5sig_info = NULL;
2169 }
2170#endif
2171
2172#ifdef CONFIG_NET_DMA
2173 /* Cleans up our sk_async_wait_queue */
2174 __skb_queue_purge(&sk->sk_async_wait_queue);
2175#endif
2176
2177 /* Clean prequeue, it must be empty really */
2178 __skb_queue_purge(&tp->ucopy.prequeue);
2179
2180 /* Clean up a referenced TCP bind bucket. */
2181 if (inet_csk(sk)->icsk_bind_hash)
2182 inet_put_port(sk);
2183
2184 BUG_ON(tp->fastopen_rsk != NULL);
2185
2186 /* If socket is aborted during connect operation */
2187 tcp_free_fastopen_req(tp);
2188
2189 sk_sockets_allocated_dec(sk);
2190 sock_release_memcg(sk);
2191}
2192EXPORT_SYMBOL(tcp_v4_destroy_sock);
2193
2194#ifdef CONFIG_PROC_FS
2195/* Proc filesystem TCP sock list dumping. */
2196
2197/*
2198 * Get next listener socket follow cur. If cur is NULL, get first socket
2199 * starting from bucket given in st->bucket; when st->bucket is zero the
2200 * very first socket in the hash table is returned.
2201 */
2202static void *listening_get_next(struct seq_file *seq, void *cur)
2203{
2204 struct inet_connection_sock *icsk;
2205 struct hlist_nulls_node *node;
2206 struct sock *sk = cur;
2207 struct inet_listen_hashbucket *ilb;
2208 struct tcp_iter_state *st = seq->private;
2209 struct net *net = seq_file_net(seq);
2210
2211 if (!sk) {
2212 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2213 spin_lock_bh(&ilb->lock);
2214 sk = sk_nulls_head(&ilb->head);
2215 st->offset = 0;
2216 goto get_sk;
2217 }
2218 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2219 ++st->num;
2220 ++st->offset;
2221
2222 if (st->state == TCP_SEQ_STATE_OPENREQ) {
2223 struct request_sock *req = cur;
2224
2225 icsk = inet_csk(st->syn_wait_sk);
2226 req = req->dl_next;
2227 while (1) {
2228 while (req) {
2229 if (req->rsk_ops->family == st->family) {
2230 cur = req;
2231 goto out;
2232 }
2233 req = req->dl_next;
2234 }
2235 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
2236 break;
2237get_req:
2238 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
2239 }
2240 sk = sk_nulls_next(st->syn_wait_sk);
2241 st->state = TCP_SEQ_STATE_LISTENING;
2242 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2243 } else {
2244 icsk = inet_csk(sk);
2245 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2246 if (reqsk_queue_len(&icsk->icsk_accept_queue))
2247 goto start_req;
2248 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2249 sk = sk_nulls_next(sk);
2250 }
2251get_sk:
2252 sk_nulls_for_each_from(sk, node) {
2253 if (!net_eq(sock_net(sk), net))
2254 continue;
2255 if (sk->sk_family == st->family) {
2256 cur = sk;
2257 goto out;
2258 }
2259 icsk = inet_csk(sk);
2260 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2261 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
2262start_req:
2263 st->uid = sock_i_uid(sk);
2264 st->syn_wait_sk = sk;
2265 st->state = TCP_SEQ_STATE_OPENREQ;
2266 st->sbucket = 0;
2267 goto get_req;
2268 }
2269 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2270 }
2271 spin_unlock_bh(&ilb->lock);
2272 st->offset = 0;
2273 if (++st->bucket < INET_LHTABLE_SIZE) {
2274 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2275 spin_lock_bh(&ilb->lock);
2276 sk = sk_nulls_head(&ilb->head);
2277 goto get_sk;
2278 }
2279 cur = NULL;
2280out:
2281 return cur;
2282}
2283
2284static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
2285{
2286 struct tcp_iter_state *st = seq->private;
2287 void *rc;
2288
2289 st->bucket = 0;
2290 st->offset = 0;
2291 rc = listening_get_next(seq, NULL);
2292
2293 while (rc && *pos) {
2294 rc = listening_get_next(seq, rc);
2295 --*pos;
2296 }
2297 return rc;
2298}
2299
2300static inline bool empty_bucket(const struct tcp_iter_state *st)
2301{
2302 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain);
2303}
2304
2305/*
2306 * Get first established socket starting from bucket given in st->bucket.
2307 * If st->bucket is zero, the very first socket in the hash is returned.
2308 */
2309static void *established_get_first(struct seq_file *seq)
2310{
2311 struct tcp_iter_state *st = seq->private;
2312 struct net *net = seq_file_net(seq);
2313 void *rc = NULL;
2314
2315 st->offset = 0;
2316 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
2317 struct sock *sk;
2318 struct hlist_nulls_node *node;
2319 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
2320
2321 /* Lockless fast path for the common case of empty buckets */
2322 if (empty_bucket(st))
2323 continue;
2324
2325 spin_lock_bh(lock);
2326 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2327 if (sk->sk_family != st->family ||
2328 !net_eq(sock_net(sk), net)) {
2329 continue;
2330 }
2331 rc = sk;
2332 goto out;
2333 }
2334 spin_unlock_bh(lock);
2335 }
2336out:
2337 return rc;
2338}
2339
2340static void *established_get_next(struct seq_file *seq, void *cur)
2341{
2342 struct sock *sk = cur;
2343 struct hlist_nulls_node *node;
2344 struct tcp_iter_state *st = seq->private;
2345 struct net *net = seq_file_net(seq);
2346
2347 ++st->num;
2348 ++st->offset;
2349
2350 sk = sk_nulls_next(sk);
2351
2352 sk_nulls_for_each_from(sk, node) {
2353 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2354 return sk;
2355 }
2356
2357 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2358 ++st->bucket;
2359 return established_get_first(seq);
2360}
2361
2362static void *established_get_idx(struct seq_file *seq, loff_t pos)
2363{
2364 struct tcp_iter_state *st = seq->private;
2365 void *rc;
2366
2367 st->bucket = 0;
2368 rc = established_get_first(seq);
2369
2370 while (rc && pos) {
2371 rc = established_get_next(seq, rc);
2372 --pos;
2373 }
2374 return rc;
2375}
2376
2377static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2378{
2379 void *rc;
2380 struct tcp_iter_state *st = seq->private;
2381
2382 st->state = TCP_SEQ_STATE_LISTENING;
2383 rc = listening_get_idx(seq, &pos);
2384
2385 if (!rc) {
2386 st->state = TCP_SEQ_STATE_ESTABLISHED;
2387 rc = established_get_idx(seq, pos);
2388 }
2389
2390 return rc;
2391}
2392
2393static void *tcp_seek_last_pos(struct seq_file *seq)
2394{
2395 struct tcp_iter_state *st = seq->private;
2396 int offset = st->offset;
2397 int orig_num = st->num;
2398 void *rc = NULL;
2399
2400 switch (st->state) {
2401 case TCP_SEQ_STATE_OPENREQ:
2402 case TCP_SEQ_STATE_LISTENING:
2403 if (st->bucket >= INET_LHTABLE_SIZE)
2404 break;
2405 st->state = TCP_SEQ_STATE_LISTENING;
2406 rc = listening_get_next(seq, NULL);
2407 while (offset-- && rc)
2408 rc = listening_get_next(seq, rc);
2409 if (rc)
2410 break;
2411 st->bucket = 0;
2412 st->state = TCP_SEQ_STATE_ESTABLISHED;
2413 /* Fallthrough */
2414 case TCP_SEQ_STATE_ESTABLISHED:
2415 if (st->bucket > tcp_hashinfo.ehash_mask)
2416 break;
2417 rc = established_get_first(seq);
2418 while (offset-- && rc)
2419 rc = established_get_next(seq, rc);
2420 }
2421
2422 st->num = orig_num;
2423
2424 return rc;
2425}
2426
2427static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2428{
2429 struct tcp_iter_state *st = seq->private;
2430 void *rc;
2431
2432 if (*pos && *pos == st->last_pos) {
2433 rc = tcp_seek_last_pos(seq);
2434 if (rc)
2435 goto out;
2436 }
2437
2438 st->state = TCP_SEQ_STATE_LISTENING;
2439 st->num = 0;
2440 st->bucket = 0;
2441 st->offset = 0;
2442 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2443
2444out:
2445 st->last_pos = *pos;
2446 return rc;
2447}
2448
2449static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2450{
2451 struct tcp_iter_state *st = seq->private;
2452 void *rc = NULL;
2453
2454 if (v == SEQ_START_TOKEN) {
2455 rc = tcp_get_idx(seq, 0);
2456 goto out;
2457 }
2458
2459 switch (st->state) {
2460 case TCP_SEQ_STATE_OPENREQ:
2461 case TCP_SEQ_STATE_LISTENING:
2462 rc = listening_get_next(seq, v);
2463 if (!rc) {
2464 st->state = TCP_SEQ_STATE_ESTABLISHED;
2465 st->bucket = 0;
2466 st->offset = 0;
2467 rc = established_get_first(seq);
2468 }
2469 break;
2470 case TCP_SEQ_STATE_ESTABLISHED:
2471 rc = established_get_next(seq, v);
2472 break;
2473 }
2474out:
2475 ++*pos;
2476 st->last_pos = *pos;
2477 return rc;
2478}
2479
2480static void tcp_seq_stop(struct seq_file *seq, void *v)
2481{
2482 struct tcp_iter_state *st = seq->private;
2483
2484 switch (st->state) {
2485 case TCP_SEQ_STATE_OPENREQ:
2486 if (v) {
2487 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2488 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2489 }
2490 case TCP_SEQ_STATE_LISTENING:
2491 if (v != SEQ_START_TOKEN)
2492 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2493 break;
2494 case TCP_SEQ_STATE_ESTABLISHED:
2495 if (v)
2496 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2497 break;
2498 }
2499}
2500
2501int tcp_seq_open(struct inode *inode, struct file *file)
2502{
2503 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode);
2504 struct tcp_iter_state *s;
2505 int err;
2506
2507 err = seq_open_net(inode, file, &afinfo->seq_ops,
2508 sizeof(struct tcp_iter_state));
2509 if (err < 0)
2510 return err;
2511
2512 s = ((struct seq_file *)file->private_data)->private;
2513 s->family = afinfo->family;
2514 s->last_pos = 0;
2515 return 0;
2516}
2517EXPORT_SYMBOL(tcp_seq_open);
2518
2519int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2520{
2521 int rc = 0;
2522 struct proc_dir_entry *p;
2523
2524 afinfo->seq_ops.start = tcp_seq_start;
2525 afinfo->seq_ops.next = tcp_seq_next;
2526 afinfo->seq_ops.stop = tcp_seq_stop;
2527
2528 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2529 afinfo->seq_fops, afinfo);
2530 if (!p)
2531 rc = -ENOMEM;
2532 return rc;
2533}
2534EXPORT_SYMBOL(tcp_proc_register);
2535
2536void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2537{
2538 remove_proc_entry(afinfo->name, net->proc_net);
2539}
2540EXPORT_SYMBOL(tcp_proc_unregister);
2541
2542static void get_openreq4(const struct sock *sk, const struct request_sock *req,
2543 struct seq_file *f, int i, kuid_t uid)
2544{
2545 const struct inet_request_sock *ireq = inet_rsk(req);
2546 long delta = req->expires - jiffies;
2547
2548 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2549 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
2550 i,
2551 ireq->ir_loc_addr,
2552 ntohs(inet_sk(sk)->inet_sport),
2553 ireq->ir_rmt_addr,
2554 ntohs(ireq->ir_rmt_port),
2555 TCP_SYN_RECV,
2556 0, 0, /* could print option size, but that is af dependent. */
2557 1, /* timers active (only the expire timer) */
2558 jiffies_delta_to_clock_t(delta),
2559 req->num_timeout,
2560 from_kuid_munged(seq_user_ns(f), uid),
2561 0, /* non standard timer */
2562 0, /* open_requests have no inode */
2563 atomic_read(&sk->sk_refcnt),
2564 req);
2565}
2566
2567static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
2568{
2569 int timer_active;
2570 unsigned long timer_expires;
2571 const struct tcp_sock *tp = tcp_sk(sk);
2572 const struct inet_connection_sock *icsk = inet_csk(sk);
2573 const struct inet_sock *inet = inet_sk(sk);
2574 struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;
2575 __be32 dest = inet->inet_daddr;
2576 __be32 src = inet->inet_rcv_saddr;
2577 __u16 destp = ntohs(inet->inet_dport);
2578 __u16 srcp = ntohs(inet->inet_sport);
2579 int rx_queue;
2580
2581 if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
2582 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
2583 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
2584 timer_active = 1;
2585 timer_expires = icsk->icsk_timeout;
2586 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2587 timer_active = 4;
2588 timer_expires = icsk->icsk_timeout;
2589 } else if (timer_pending(&sk->sk_timer)) {
2590 timer_active = 2;
2591 timer_expires = sk->sk_timer.expires;
2592 } else {
2593 timer_active = 0;
2594 timer_expires = jiffies;
2595 }
2596
2597 if (sk->sk_state == TCP_LISTEN)
2598 rx_queue = sk->sk_ack_backlog;
2599 else
2600 /*
2601 * because we dont lock socket, we might find a transient negative value
2602 */
2603 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
2604
2605 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2606 "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
2607 i, src, srcp, dest, destp, sk->sk_state,
2608 tp->write_seq - tp->snd_una,
2609 rx_queue,
2610 timer_active,
2611 jiffies_delta_to_clock_t(timer_expires - jiffies),
2612 icsk->icsk_retransmits,
2613 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
2614 icsk->icsk_probes_out,
2615 sock_i_ino(sk),
2616 atomic_read(&sk->sk_refcnt), sk,
2617 jiffies_to_clock_t(icsk->icsk_rto),
2618 jiffies_to_clock_t(icsk->icsk_ack.ato),
2619 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2620 tp->snd_cwnd,
2621 sk->sk_state == TCP_LISTEN ?
2622 (fastopenq ? fastopenq->max_qlen : 0) :
2623 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
2624}
2625
2626static void get_timewait4_sock(const struct inet_timewait_sock *tw,
2627 struct seq_file *f, int i)
2628{
2629 __be32 dest, src;
2630 __u16 destp, srcp;
2631 s32 delta = tw->tw_ttd - inet_tw_time_stamp();
2632
2633 dest = tw->tw_daddr;
2634 src = tw->tw_rcv_saddr;
2635 destp = ntohs(tw->tw_dport);
2636 srcp = ntohs(tw->tw_sport);
2637
2638 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2639 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
2640 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2641 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
2642 atomic_read(&tw->tw_refcnt), tw);
2643}
2644
2645#define TMPSZ 150
2646
2647static int tcp4_seq_show(struct seq_file *seq, void *v)
2648{
2649 struct tcp_iter_state *st;
2650 struct sock *sk = v;
2651
2652 seq_setwidth(seq, TMPSZ - 1);
2653 if (v == SEQ_START_TOKEN) {
2654 seq_puts(seq, " sl local_address rem_address st tx_queue "
2655 "rx_queue tr tm->when retrnsmt uid timeout "
2656 "inode");
2657 goto out;
2658 }
2659 st = seq->private;
2660
2661 switch (st->state) {
2662 case TCP_SEQ_STATE_LISTENING:
2663 case TCP_SEQ_STATE_ESTABLISHED:
2664 if (sk->sk_state == TCP_TIME_WAIT)
2665 get_timewait4_sock(v, seq, st->num);
2666 else
2667 get_tcp4_sock(v, seq, st->num);
2668 break;
2669 case TCP_SEQ_STATE_OPENREQ:
2670 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid);
2671 break;
2672 }
2673out:
2674 seq_pad(seq, '\n');
2675 return 0;
2676}
2677
2678static const struct file_operations tcp_afinfo_seq_fops = {
2679 .owner = THIS_MODULE,
2680 .open = tcp_seq_open,
2681 .read = seq_read,
2682 .llseek = seq_lseek,
2683 .release = seq_release_net
2684};
2685
2686static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2687 .name = "tcp",
2688 .family = AF_INET,
2689 .seq_fops = &tcp_afinfo_seq_fops,
2690 .seq_ops = {
2691 .show = tcp4_seq_show,
2692 },
2693};
2694
2695static int __net_init tcp4_proc_init_net(struct net *net)
2696{
2697 return tcp_proc_register(net, &tcp4_seq_afinfo);
2698}
2699
2700static void __net_exit tcp4_proc_exit_net(struct net *net)
2701{
2702 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2703}
2704
2705static struct pernet_operations tcp4_net_ops = {
2706 .init = tcp4_proc_init_net,
2707 .exit = tcp4_proc_exit_net,
2708};
2709
2710int __init tcp4_proc_init(void)
2711{
2712 return register_pernet_subsys(&tcp4_net_ops);
2713}
2714
2715void tcp4_proc_exit(void)
2716{
2717 unregister_pernet_subsys(&tcp4_net_ops);
2718}
2719#endif /* CONFIG_PROC_FS */
2720
2721struct proto tcp_prot = {
2722 .name = "TCP",
2723 .owner = THIS_MODULE,
2724 .close = tcp_close,
2725 .connect = tcp_v4_connect,
2726 .disconnect = tcp_disconnect,
2727 .accept = inet_csk_accept,
2728 .ioctl = tcp_ioctl,
2729 .init = tcp_v4_init_sock,
2730 .destroy = tcp_v4_destroy_sock,
2731 .shutdown = tcp_shutdown,
2732 .setsockopt = tcp_setsockopt,
2733 .getsockopt = tcp_getsockopt,
2734 .recvmsg = tcp_recvmsg,
2735 .sendmsg = tcp_sendmsg,
2736 .sendpage = tcp_sendpage,
2737 .backlog_rcv = tcp_v4_do_rcv,
2738 .release_cb = tcp_release_cb,
2739 .mtu_reduced = tcp_v4_mtu_reduced,
2740 .hash = inet_hash,
2741 .unhash = inet_unhash,
2742 .get_port = inet_csk_get_port,
2743 .enter_memory_pressure = tcp_enter_memory_pressure,
2744 .stream_memory_free = tcp_stream_memory_free,
2745 .sockets_allocated = &tcp_sockets_allocated,
2746 .orphan_count = &tcp_orphan_count,
2747 .memory_allocated = &tcp_memory_allocated,
2748 .memory_pressure = &tcp_memory_pressure,
2749 .sysctl_mem = sysctl_tcp_mem,
2750 .sysctl_wmem = sysctl_tcp_wmem,
2751 .sysctl_rmem = sysctl_tcp_rmem,
2752 .max_header = MAX_TCP_HEADER,
2753 .obj_size = sizeof(struct tcp_sock),
2754 .slab_flags = SLAB_DESTROY_BY_RCU,
2755 .twsk_prot = &tcp_timewait_sock_ops,
2756 .rsk_prot = &tcp_request_sock_ops,
2757 .h.hashinfo = &tcp_hashinfo,
2758 .no_autobind = true,
2759#ifdef CONFIG_COMPAT
2760 .compat_setsockopt = compat_tcp_setsockopt,
2761 .compat_getsockopt = compat_tcp_getsockopt,
2762#endif
2763#ifdef CONFIG_MEMCG_KMEM
2764 .init_cgroup = tcp_init_cgroup,
2765 .destroy_cgroup = tcp_destroy_cgroup,
2766 .proto_cgroup = tcp_proto_cgroup,
2767#endif
2768};
2769EXPORT_SYMBOL(tcp_prot);
2770
2771static int __net_init tcp_sk_init(struct net *net)
2772{
2773 net->ipv4.sysctl_tcp_ecn = 2;
2774 return 0;
2775}
2776
2777static void __net_exit tcp_sk_exit(struct net *net)
2778{
2779}
2780
2781static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
2782{
2783 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2784}
2785
2786static struct pernet_operations __net_initdata tcp_sk_ops = {
2787 .init = tcp_sk_init,
2788 .exit = tcp_sk_exit,
2789 .exit_batch = tcp_sk_exit_batch,
2790};
2791
2792void __init tcp_v4_init(void)
2793{
2794 inet_hashinfo_init(&tcp_hashinfo);
2795 if (register_pernet_subsys(&tcp_sk_ops))
2796 panic("Failed to create the TCP control socket.\n");
2797}