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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 #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/secure_seq.h>
76 #include <net/tcp_memcontrol.h>
77 #include <net/busy_poll.h>
78
79 #include <linux/inet.h>
80 #include <linux/ipv6.h>
81 #include <linux/stddef.h>
82 #include <linux/proc_fs.h>
83 #include <linux/seq_file.h>
84
85 #include <linux/crypto.h>
86 #include <linux/scatterlist.h>
87
88 int sysctl_tcp_tw_reuse __read_mostly;
89 int sysctl_tcp_low_latency __read_mostly;
90 EXPORT_SYMBOL(sysctl_tcp_low_latency);
91
92 #ifdef CONFIG_TCP_MD5SIG
93 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
94 __be32 daddr, __be32 saddr, const struct tcphdr *th);
95 #endif
96
97 struct inet_hashinfo tcp_hashinfo;
98 EXPORT_SYMBOL(tcp_hashinfo);
99
100 static __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
101 {
102 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
103 ip_hdr(skb)->saddr,
104 tcp_hdr(skb)->dest,
105 tcp_hdr(skb)->source);
106 }
107
108 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
109 {
110 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
111 struct tcp_sock *tp = tcp_sk(sk);
112
113 /* With PAWS, it is safe from the viewpoint
114 of data integrity. Even without PAWS it is safe provided sequence
115 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
116
117 Actually, the idea is close to VJ's one, only timestamp cache is
118 held not per host, but per port pair and TW bucket is used as state
119 holder.
120
121 If TW bucket has been already destroyed we fall back to VJ's scheme
122 and use initial timestamp retrieved from peer table.
123 */
124 if (tcptw->tw_ts_recent_stamp &&
125 (!twp || (sysctl_tcp_tw_reuse &&
126 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
127 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
128 if (tp->write_seq == 0)
129 tp->write_seq = 1;
130 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
131 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
132 sock_hold(sktw);
133 return 1;
134 }
135
136 return 0;
137 }
138 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
139
140 /* This will initiate an outgoing connection. */
141 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
142 {
143 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
144 struct inet_sock *inet = inet_sk(sk);
145 struct tcp_sock *tp = tcp_sk(sk);
146 __be16 orig_sport, orig_dport;
147 __be32 daddr, nexthop;
148 struct flowi4 *fl4;
149 struct rtable *rt;
150 int err;
151 struct ip_options_rcu *inet_opt;
152
153 if (addr_len < sizeof(struct sockaddr_in))
154 return -EINVAL;
155
156 if (usin->sin_family != AF_INET)
157 return -EAFNOSUPPORT;
158
159 nexthop = daddr = usin->sin_addr.s_addr;
160 inet_opt = rcu_dereference_protected(inet->inet_opt,
161 sock_owned_by_user(sk));
162 if (inet_opt && inet_opt->opt.srr) {
163 if (!daddr)
164 return -EINVAL;
165 nexthop = inet_opt->opt.faddr;
166 }
167
168 orig_sport = inet->inet_sport;
169 orig_dport = usin->sin_port;
170 fl4 = &inet->cork.fl.u.ip4;
171 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
172 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
173 IPPROTO_TCP,
174 orig_sport, orig_dport, sk);
175 if (IS_ERR(rt)) {
176 err = PTR_ERR(rt);
177 if (err == -ENETUNREACH)
178 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
179 return err;
180 }
181
182 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
183 ip_rt_put(rt);
184 return -ENETUNREACH;
185 }
186
187 if (!inet_opt || !inet_opt->opt.srr)
188 daddr = fl4->daddr;
189
190 if (!inet->inet_saddr)
191 inet->inet_saddr = fl4->saddr;
192 sk_rcv_saddr_set(sk, inet->inet_saddr);
193
194 if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
195 /* Reset inherited state */
196 tp->rx_opt.ts_recent = 0;
197 tp->rx_opt.ts_recent_stamp = 0;
198 if (likely(!tp->repair))
199 tp->write_seq = 0;
200 }
201
202 if (tcp_death_row.sysctl_tw_recycle &&
203 !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
204 tcp_fetch_timewait_stamp(sk, &rt->dst);
205
206 inet->inet_dport = usin->sin_port;
207 sk_daddr_set(sk, daddr);
208
209 inet_csk(sk)->icsk_ext_hdr_len = 0;
210 if (inet_opt)
211 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
212
213 tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
214
215 /* Socket identity is still unknown (sport may be zero).
216 * However we set state to SYN-SENT and not releasing socket
217 * lock select source port, enter ourselves into the hash tables and
218 * complete initialization after this.
219 */
220 tcp_set_state(sk, TCP_SYN_SENT);
221 err = inet_hash_connect(&tcp_death_row, sk);
222 if (err)
223 goto failure;
224
225 inet_set_txhash(sk);
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
254 failure:
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 }
265 EXPORT_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 */
272 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 EXPORT_SYMBOL(tcp_v4_mtu_reduced);
304
305 static void do_redirect(struct sk_buff *skb, struct sock *sk)
306 {
307 struct dst_entry *dst = __sk_dst_check(sk, 0);
308
309 if (dst)
310 dst->ops->redirect(dst, sk, skb);
311 }
312
313
314 /* handle ICMP messages on TCP_NEW_SYN_RECV request sockets */
315 void tcp_req_err(struct sock *sk, u32 seq)
316 {
317 struct request_sock *req = inet_reqsk(sk);
318 struct net *net = sock_net(sk);
319
320 /* ICMPs are not backlogged, hence we cannot get
321 * an established socket here.
322 */
323 WARN_ON(req->sk);
324
325 if (seq != tcp_rsk(req)->snt_isn) {
326 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
327 reqsk_put(req);
328 } else {
329 /*
330 * Still in SYN_RECV, just remove it silently.
331 * There is no good way to pass the error to the newly
332 * created socket, and POSIX does not want network
333 * errors returned from accept().
334 */
335 NET_INC_STATS_BH(net, LINUX_MIB_LISTENDROPS);
336 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
337 }
338 }
339 EXPORT_SYMBOL(tcp_req_err);
340
341 /*
342 * This routine is called by the ICMP module when it gets some
343 * sort of error condition. If err < 0 then the socket should
344 * be closed and the error returned to the user. If err > 0
345 * it's just the icmp type << 8 | icmp code. After adjustment
346 * header points to the first 8 bytes of the tcp header. We need
347 * to find the appropriate port.
348 *
349 * The locking strategy used here is very "optimistic". When
350 * someone else accesses the socket the ICMP is just dropped
351 * and for some paths there is no check at all.
352 * A more general error queue to queue errors for later handling
353 * is probably better.
354 *
355 */
356
357 void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
358 {
359 const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
360 struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
361 struct inet_connection_sock *icsk;
362 struct tcp_sock *tp;
363 struct inet_sock *inet;
364 const int type = icmp_hdr(icmp_skb)->type;
365 const int code = icmp_hdr(icmp_skb)->code;
366 struct sock *sk;
367 struct sk_buff *skb;
368 struct request_sock *fastopen;
369 __u32 seq, snd_una;
370 __u32 remaining;
371 int err;
372 struct net *net = dev_net(icmp_skb->dev);
373
374 sk = __inet_lookup_established(net, &tcp_hashinfo, iph->daddr,
375 th->dest, iph->saddr, ntohs(th->source),
376 inet_iif(icmp_skb));
377 if (!sk) {
378 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
379 return;
380 }
381 if (sk->sk_state == TCP_TIME_WAIT) {
382 inet_twsk_put(inet_twsk(sk));
383 return;
384 }
385 seq = ntohl(th->seq);
386 if (sk->sk_state == TCP_NEW_SYN_RECV)
387 return tcp_req_err(sk, seq);
388
389 bh_lock_sock(sk);
390 /* If too many ICMPs get dropped on busy
391 * servers this needs to be solved differently.
392 * We do take care of PMTU discovery (RFC1191) special case :
393 * we can receive locally generated ICMP messages while socket is held.
394 */
395 if (sock_owned_by_user(sk)) {
396 if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
397 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
398 }
399 if (sk->sk_state == TCP_CLOSE)
400 goto out;
401
402 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
403 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
404 goto out;
405 }
406
407 icsk = inet_csk(sk);
408 tp = tcp_sk(sk);
409 /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
410 fastopen = tp->fastopen_rsk;
411 snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
412 if (sk->sk_state != TCP_LISTEN &&
413 !between(seq, snd_una, tp->snd_nxt)) {
414 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
415 goto out;
416 }
417
418 switch (type) {
419 case ICMP_REDIRECT:
420 do_redirect(icmp_skb, sk);
421 goto out;
422 case ICMP_SOURCE_QUENCH:
423 /* Just silently ignore these. */
424 goto out;
425 case ICMP_PARAMETERPROB:
426 err = EPROTO;
427 break;
428 case ICMP_DEST_UNREACH:
429 if (code > NR_ICMP_UNREACH)
430 goto out;
431
432 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
433 /* We are not interested in TCP_LISTEN and open_requests
434 * (SYN-ACKs send out by Linux are always <576bytes so
435 * they should go through unfragmented).
436 */
437 if (sk->sk_state == TCP_LISTEN)
438 goto out;
439
440 tp->mtu_info = info;
441 if (!sock_owned_by_user(sk)) {
442 tcp_v4_mtu_reduced(sk);
443 } else {
444 if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
445 sock_hold(sk);
446 }
447 goto out;
448 }
449
450 err = icmp_err_convert[code].errno;
451 /* check if icmp_skb allows revert of backoff
452 * (see draft-zimmermann-tcp-lcd) */
453 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
454 break;
455 if (seq != tp->snd_una || !icsk->icsk_retransmits ||
456 !icsk->icsk_backoff || fastopen)
457 break;
458
459 if (sock_owned_by_user(sk))
460 break;
461
462 icsk->icsk_backoff--;
463 icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) :
464 TCP_TIMEOUT_INIT;
465 icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
466
467 skb = tcp_write_queue_head(sk);
468 BUG_ON(!skb);
469
470 remaining = icsk->icsk_rto -
471 min(icsk->icsk_rto,
472 tcp_time_stamp - tcp_skb_timestamp(skb));
473
474 if (remaining) {
475 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
476 remaining, TCP_RTO_MAX);
477 } else {
478 /* RTO revert clocked out retransmission.
479 * Will retransmit now */
480 tcp_retransmit_timer(sk);
481 }
482
483 break;
484 case ICMP_TIME_EXCEEDED:
485 err = EHOSTUNREACH;
486 break;
487 default:
488 goto out;
489 }
490
491 switch (sk->sk_state) {
492 case TCP_SYN_SENT:
493 case TCP_SYN_RECV:
494 /* Only in fast or simultaneous open. If a fast open socket is
495 * is already accepted it is treated as a connected one below.
496 */
497 if (fastopen && !fastopen->sk)
498 break;
499
500 if (!sock_owned_by_user(sk)) {
501 sk->sk_err = err;
502
503 sk->sk_error_report(sk);
504
505 tcp_done(sk);
506 } else {
507 sk->sk_err_soft = err;
508 }
509 goto out;
510 }
511
512 /* If we've already connected we will keep trying
513 * until we time out, or the user gives up.
514 *
515 * rfc1122 4.2.3.9 allows to consider as hard errors
516 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
517 * but it is obsoleted by pmtu discovery).
518 *
519 * Note, that in modern internet, where routing is unreliable
520 * and in each dark corner broken firewalls sit, sending random
521 * errors ordered by their masters even this two messages finally lose
522 * their original sense (even Linux sends invalid PORT_UNREACHs)
523 *
524 * Now we are in compliance with RFCs.
525 * --ANK (980905)
526 */
527
528 inet = inet_sk(sk);
529 if (!sock_owned_by_user(sk) && inet->recverr) {
530 sk->sk_err = err;
531 sk->sk_error_report(sk);
532 } else { /* Only an error on timeout */
533 sk->sk_err_soft = err;
534 }
535
536 out:
537 bh_unlock_sock(sk);
538 sock_put(sk);
539 }
540
541 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
542 {
543 struct tcphdr *th = tcp_hdr(skb);
544
545 if (skb->ip_summed == CHECKSUM_PARTIAL) {
546 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
547 skb->csum_start = skb_transport_header(skb) - skb->head;
548 skb->csum_offset = offsetof(struct tcphdr, check);
549 } else {
550 th->check = tcp_v4_check(skb->len, saddr, daddr,
551 csum_partial(th,
552 th->doff << 2,
553 skb->csum));
554 }
555 }
556
557 /* This routine computes an IPv4 TCP checksum. */
558 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
559 {
560 const struct inet_sock *inet = inet_sk(sk);
561
562 __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
563 }
564 EXPORT_SYMBOL(tcp_v4_send_check);
565
566 /*
567 * This routine will send an RST to the other tcp.
568 *
569 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
570 * for reset.
571 * Answer: if a packet caused RST, it is not for a socket
572 * existing in our system, if it is matched to a socket,
573 * it is just duplicate segment or bug in other side's TCP.
574 * So that we build reply only basing on parameters
575 * arrived with segment.
576 * Exception: precedence violation. We do not implement it in any case.
577 */
578
579 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
580 {
581 const struct tcphdr *th = tcp_hdr(skb);
582 struct {
583 struct tcphdr th;
584 #ifdef CONFIG_TCP_MD5SIG
585 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
586 #endif
587 } rep;
588 struct ip_reply_arg arg;
589 #ifdef CONFIG_TCP_MD5SIG
590 struct tcp_md5sig_key *key;
591 const __u8 *hash_location = NULL;
592 unsigned char newhash[16];
593 int genhash;
594 struct sock *sk1 = NULL;
595 #endif
596 struct net *net;
597
598 /* Never send a reset in response to a reset. */
599 if (th->rst)
600 return;
601
602 /* If sk not NULL, it means we did a successful lookup and incoming
603 * route had to be correct. prequeue might have dropped our dst.
604 */
605 if (!sk && skb_rtable(skb)->rt_type != RTN_LOCAL)
606 return;
607
608 /* Swap the send and the receive. */
609 memset(&rep, 0, sizeof(rep));
610 rep.th.dest = th->source;
611 rep.th.source = th->dest;
612 rep.th.doff = sizeof(struct tcphdr) / 4;
613 rep.th.rst = 1;
614
615 if (th->ack) {
616 rep.th.seq = th->ack_seq;
617 } else {
618 rep.th.ack = 1;
619 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
620 skb->len - (th->doff << 2));
621 }
622
623 memset(&arg, 0, sizeof(arg));
624 arg.iov[0].iov_base = (unsigned char *)&rep;
625 arg.iov[0].iov_len = sizeof(rep.th);
626
627 net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
628 #ifdef CONFIG_TCP_MD5SIG
629 hash_location = tcp_parse_md5sig_option(th);
630 if (!sk && hash_location) {
631 /*
632 * active side is lost. Try to find listening socket through
633 * source port, and then find md5 key through listening socket.
634 * we are not loose security here:
635 * Incoming packet is checked with md5 hash with finding key,
636 * no RST generated if md5 hash doesn't match.
637 */
638 sk1 = __inet_lookup_listener(net,
639 &tcp_hashinfo, ip_hdr(skb)->saddr,
640 th->source, ip_hdr(skb)->daddr,
641 ntohs(th->source), inet_iif(skb));
642 /* don't send rst if it can't find key */
643 if (!sk1)
644 return;
645 rcu_read_lock();
646 key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
647 &ip_hdr(skb)->saddr, AF_INET);
648 if (!key)
649 goto release_sk1;
650
651 genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
652 if (genhash || memcmp(hash_location, newhash, 16) != 0)
653 goto release_sk1;
654 } else {
655 key = sk ? tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
656 &ip_hdr(skb)->saddr,
657 AF_INET) : NULL;
658 }
659
660 if (key) {
661 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
662 (TCPOPT_NOP << 16) |
663 (TCPOPT_MD5SIG << 8) |
664 TCPOLEN_MD5SIG);
665 /* Update length and the length the header thinks exists */
666 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
667 rep.th.doff = arg.iov[0].iov_len / 4;
668
669 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
670 key, ip_hdr(skb)->saddr,
671 ip_hdr(skb)->daddr, &rep.th);
672 }
673 #endif
674 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
675 ip_hdr(skb)->saddr, /* XXX */
676 arg.iov[0].iov_len, IPPROTO_TCP, 0);
677 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
678 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
679 /* When socket is gone, all binding information is lost.
680 * routing might fail in this case. No choice here, if we choose to force
681 * input interface, we will misroute in case of asymmetric route.
682 */
683 if (sk)
684 arg.bound_dev_if = sk->sk_bound_dev_if;
685
686 arg.tos = ip_hdr(skb)->tos;
687 ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
688 skb, &TCP_SKB_CB(skb)->header.h4.opt,
689 ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
690 &arg, arg.iov[0].iov_len);
691
692 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
693 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
694
695 #ifdef CONFIG_TCP_MD5SIG
696 release_sk1:
697 if (sk1) {
698 rcu_read_unlock();
699 sock_put(sk1);
700 }
701 #endif
702 }
703
704 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
705 outside socket context is ugly, certainly. What can I do?
706 */
707
708 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
709 u32 win, u32 tsval, u32 tsecr, int oif,
710 struct tcp_md5sig_key *key,
711 int reply_flags, u8 tos)
712 {
713 const struct tcphdr *th = tcp_hdr(skb);
714 struct {
715 struct tcphdr th;
716 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
717 #ifdef CONFIG_TCP_MD5SIG
718 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
719 #endif
720 ];
721 } rep;
722 struct ip_reply_arg arg;
723 struct net *net = dev_net(skb_dst(skb)->dev);
724
725 memset(&rep.th, 0, sizeof(struct tcphdr));
726 memset(&arg, 0, sizeof(arg));
727
728 arg.iov[0].iov_base = (unsigned char *)&rep;
729 arg.iov[0].iov_len = sizeof(rep.th);
730 if (tsecr) {
731 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
732 (TCPOPT_TIMESTAMP << 8) |
733 TCPOLEN_TIMESTAMP);
734 rep.opt[1] = htonl(tsval);
735 rep.opt[2] = htonl(tsecr);
736 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
737 }
738
739 /* Swap the send and the receive. */
740 rep.th.dest = th->source;
741 rep.th.source = th->dest;
742 rep.th.doff = arg.iov[0].iov_len / 4;
743 rep.th.seq = htonl(seq);
744 rep.th.ack_seq = htonl(ack);
745 rep.th.ack = 1;
746 rep.th.window = htons(win);
747
748 #ifdef CONFIG_TCP_MD5SIG
749 if (key) {
750 int offset = (tsecr) ? 3 : 0;
751
752 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
753 (TCPOPT_NOP << 16) |
754 (TCPOPT_MD5SIG << 8) |
755 TCPOLEN_MD5SIG);
756 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
757 rep.th.doff = arg.iov[0].iov_len/4;
758
759 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
760 key, ip_hdr(skb)->saddr,
761 ip_hdr(skb)->daddr, &rep.th);
762 }
763 #endif
764 arg.flags = reply_flags;
765 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
766 ip_hdr(skb)->saddr, /* XXX */
767 arg.iov[0].iov_len, IPPROTO_TCP, 0);
768 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
769 if (oif)
770 arg.bound_dev_if = oif;
771 arg.tos = tos;
772 ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),
773 skb, &TCP_SKB_CB(skb)->header.h4.opt,
774 ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
775 &arg, arg.iov[0].iov_len);
776
777 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
778 }
779
780 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
781 {
782 struct inet_timewait_sock *tw = inet_twsk(sk);
783 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
784
785 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
786 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
787 tcp_time_stamp + tcptw->tw_ts_offset,
788 tcptw->tw_ts_recent,
789 tw->tw_bound_dev_if,
790 tcp_twsk_md5_key(tcptw),
791 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
792 tw->tw_tos
793 );
794
795 inet_twsk_put(tw);
796 }
797
798 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
799 struct request_sock *req)
800 {
801 /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
802 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
803 */
804 tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
805 tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
806 tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
807 tcp_time_stamp,
808 req->ts_recent,
809 0,
810 tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
811 AF_INET),
812 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
813 ip_hdr(skb)->tos);
814 }
815
816 /*
817 * Send a SYN-ACK after having received a SYN.
818 * This still operates on a request_sock only, not on a big
819 * socket.
820 */
821 static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
822 struct flowi *fl,
823 struct request_sock *req,
824 u16 queue_mapping,
825 struct tcp_fastopen_cookie *foc)
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, foc);
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 }
847
848 return err;
849 }
850
851 /*
852 * IPv4 request_sock destructor.
853 */
854 static void tcp_v4_reqsk_destructor(struct request_sock *req)
855 {
856 kfree(inet_rsk(req)->opt);
857 }
858
859
860 #ifdef CONFIG_TCP_MD5SIG
861 /*
862 * RFC2385 MD5 checksumming requires a mapping of
863 * IP address->MD5 Key.
864 * We need to maintain these in the sk structure.
865 */
866
867 /* Find the Key structure for an address. */
868 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
869 const union tcp_md5_addr *addr,
870 int family)
871 {
872 const struct tcp_sock *tp = tcp_sk(sk);
873 struct tcp_md5sig_key *key;
874 unsigned int size = sizeof(struct in_addr);
875 const struct tcp_md5sig_info *md5sig;
876
877 /* caller either holds rcu_read_lock() or socket lock */
878 md5sig = rcu_dereference_check(tp->md5sig_info,
879 sock_owned_by_user(sk) ||
880 lockdep_is_held(&sk->sk_lock.slock));
881 if (!md5sig)
882 return NULL;
883 #if IS_ENABLED(CONFIG_IPV6)
884 if (family == AF_INET6)
885 size = sizeof(struct in6_addr);
886 #endif
887 hlist_for_each_entry_rcu(key, &md5sig->head, node) {
888 if (key->family != family)
889 continue;
890 if (!memcmp(&key->addr, addr, size))
891 return key;
892 }
893 return NULL;
894 }
895 EXPORT_SYMBOL(tcp_md5_do_lookup);
896
897 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
898 const struct sock *addr_sk)
899 {
900 const union tcp_md5_addr *addr;
901
902 addr = (const union tcp_md5_addr *)&addr_sk->sk_daddr;
903 return tcp_md5_do_lookup(sk, addr, AF_INET);
904 }
905 EXPORT_SYMBOL(tcp_v4_md5_lookup);
906
907 /* This can be called on a newly created socket, from other files */
908 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
909 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
910 {
911 /* Add Key to the list */
912 struct tcp_md5sig_key *key;
913 struct tcp_sock *tp = tcp_sk(sk);
914 struct tcp_md5sig_info *md5sig;
915
916 key = tcp_md5_do_lookup(sk, addr, family);
917 if (key) {
918 /* Pre-existing entry - just update that one. */
919 memcpy(key->key, newkey, newkeylen);
920 key->keylen = newkeylen;
921 return 0;
922 }
923
924 md5sig = rcu_dereference_protected(tp->md5sig_info,
925 sock_owned_by_user(sk));
926 if (!md5sig) {
927 md5sig = kmalloc(sizeof(*md5sig), gfp);
928 if (!md5sig)
929 return -ENOMEM;
930
931 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
932 INIT_HLIST_HEAD(&md5sig->head);
933 rcu_assign_pointer(tp->md5sig_info, md5sig);
934 }
935
936 key = sock_kmalloc(sk, sizeof(*key), gfp);
937 if (!key)
938 return -ENOMEM;
939 if (!tcp_alloc_md5sig_pool()) {
940 sock_kfree_s(sk, key, sizeof(*key));
941 return -ENOMEM;
942 }
943
944 memcpy(key->key, newkey, newkeylen);
945 key->keylen = newkeylen;
946 key->family = family;
947 memcpy(&key->addr, addr,
948 (family == AF_INET6) ? sizeof(struct in6_addr) :
949 sizeof(struct in_addr));
950 hlist_add_head_rcu(&key->node, &md5sig->head);
951 return 0;
952 }
953 EXPORT_SYMBOL(tcp_md5_do_add);
954
955 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
956 {
957 struct tcp_md5sig_key *key;
958
959 key = tcp_md5_do_lookup(sk, addr, family);
960 if (!key)
961 return -ENOENT;
962 hlist_del_rcu(&key->node);
963 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
964 kfree_rcu(key, rcu);
965 return 0;
966 }
967 EXPORT_SYMBOL(tcp_md5_do_del);
968
969 static void tcp_clear_md5_list(struct sock *sk)
970 {
971 struct tcp_sock *tp = tcp_sk(sk);
972 struct tcp_md5sig_key *key;
973 struct hlist_node *n;
974 struct tcp_md5sig_info *md5sig;
975
976 md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
977
978 hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
979 hlist_del_rcu(&key->node);
980 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
981 kfree_rcu(key, rcu);
982 }
983 }
984
985 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
986 int optlen)
987 {
988 struct tcp_md5sig cmd;
989 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
990
991 if (optlen < sizeof(cmd))
992 return -EINVAL;
993
994 if (copy_from_user(&cmd, optval, sizeof(cmd)))
995 return -EFAULT;
996
997 if (sin->sin_family != AF_INET)
998 return -EINVAL;
999
1000 if (!cmd.tcpm_keylen)
1001 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1002 AF_INET);
1003
1004 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1005 return -EINVAL;
1006
1007 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1008 AF_INET, cmd.tcpm_key, cmd.tcpm_keylen,
1009 GFP_KERNEL);
1010 }
1011
1012 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1013 __be32 daddr, __be32 saddr, int nbytes)
1014 {
1015 struct tcp4_pseudohdr *bp;
1016 struct scatterlist sg;
1017
1018 bp = &hp->md5_blk.ip4;
1019
1020 /*
1021 * 1. the TCP pseudo-header (in the order: source IP address,
1022 * destination IP address, zero-padded protocol number, and
1023 * segment length)
1024 */
1025 bp->saddr = saddr;
1026 bp->daddr = daddr;
1027 bp->pad = 0;
1028 bp->protocol = IPPROTO_TCP;
1029 bp->len = cpu_to_be16(nbytes);
1030
1031 sg_init_one(&sg, bp, sizeof(*bp));
1032 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1033 }
1034
1035 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
1036 __be32 daddr, __be32 saddr, const struct tcphdr *th)
1037 {
1038 struct tcp_md5sig_pool *hp;
1039 struct hash_desc *desc;
1040
1041 hp = tcp_get_md5sig_pool();
1042 if (!hp)
1043 goto clear_hash_noput;
1044 desc = &hp->md5_desc;
1045
1046 if (crypto_hash_init(desc))
1047 goto clear_hash;
1048 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1049 goto clear_hash;
1050 if (tcp_md5_hash_header(hp, th))
1051 goto clear_hash;
1052 if (tcp_md5_hash_key(hp, key))
1053 goto clear_hash;
1054 if (crypto_hash_final(desc, md5_hash))
1055 goto clear_hash;
1056
1057 tcp_put_md5sig_pool();
1058 return 0;
1059
1060 clear_hash:
1061 tcp_put_md5sig_pool();
1062 clear_hash_noput:
1063 memset(md5_hash, 0, 16);
1064 return 1;
1065 }
1066
1067 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1068 const struct sock *sk,
1069 const struct sk_buff *skb)
1070 {
1071 struct tcp_md5sig_pool *hp;
1072 struct hash_desc *desc;
1073 const struct tcphdr *th = tcp_hdr(skb);
1074 __be32 saddr, daddr;
1075
1076 if (sk) { /* valid for establish/request sockets */
1077 saddr = sk->sk_rcv_saddr;
1078 daddr = sk->sk_daddr;
1079 } else {
1080 const struct iphdr *iph = ip_hdr(skb);
1081 saddr = iph->saddr;
1082 daddr = iph->daddr;
1083 }
1084
1085 hp = tcp_get_md5sig_pool();
1086 if (!hp)
1087 goto clear_hash_noput;
1088 desc = &hp->md5_desc;
1089
1090 if (crypto_hash_init(desc))
1091 goto clear_hash;
1092
1093 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1094 goto clear_hash;
1095 if (tcp_md5_hash_header(hp, th))
1096 goto clear_hash;
1097 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1098 goto clear_hash;
1099 if (tcp_md5_hash_key(hp, key))
1100 goto clear_hash;
1101 if (crypto_hash_final(desc, md5_hash))
1102 goto clear_hash;
1103
1104 tcp_put_md5sig_pool();
1105 return 0;
1106
1107 clear_hash:
1108 tcp_put_md5sig_pool();
1109 clear_hash_noput:
1110 memset(md5_hash, 0, 16);
1111 return 1;
1112 }
1113 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1114
1115 /* Called with rcu_read_lock() */
1116 static bool tcp_v4_inbound_md5_hash(struct sock *sk,
1117 const struct sk_buff *skb)
1118 {
1119 /*
1120 * This gets called for each TCP segment that arrives
1121 * so we want to be efficient.
1122 * We have 3 drop cases:
1123 * o No MD5 hash and one expected.
1124 * o MD5 hash and we're not expecting one.
1125 * o MD5 hash and its wrong.
1126 */
1127 const __u8 *hash_location = NULL;
1128 struct tcp_md5sig_key *hash_expected;
1129 const struct iphdr *iph = ip_hdr(skb);
1130 const struct tcphdr *th = tcp_hdr(skb);
1131 int genhash;
1132 unsigned char newhash[16];
1133
1134 hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr,
1135 AF_INET);
1136 hash_location = tcp_parse_md5sig_option(th);
1137
1138 /* We've parsed the options - do we have a hash? */
1139 if (!hash_expected && !hash_location)
1140 return false;
1141
1142 if (hash_expected && !hash_location) {
1143 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1144 return true;
1145 }
1146
1147 if (!hash_expected && hash_location) {
1148 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1149 return true;
1150 }
1151
1152 /* Okay, so this is hash_expected and hash_location -
1153 * so we need to calculate the checksum.
1154 */
1155 genhash = tcp_v4_md5_hash_skb(newhash,
1156 hash_expected,
1157 NULL, skb);
1158
1159 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1160 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1161 &iph->saddr, ntohs(th->source),
1162 &iph->daddr, ntohs(th->dest),
1163 genhash ? " tcp_v4_calc_md5_hash failed"
1164 : "");
1165 return true;
1166 }
1167 return false;
1168 }
1169 #endif
1170
1171 static void tcp_v4_init_req(struct request_sock *req, struct sock *sk_listener,
1172 struct sk_buff *skb)
1173 {
1174 struct inet_request_sock *ireq = inet_rsk(req);
1175
1176 sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr);
1177 sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
1178 ireq->no_srccheck = inet_sk(sk_listener)->transparent;
1179 ireq->opt = tcp_v4_save_options(skb);
1180 }
1181
1182 static struct dst_entry *tcp_v4_route_req(struct sock *sk, struct flowi *fl,
1183 const struct request_sock *req,
1184 bool *strict)
1185 {
1186 struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req);
1187
1188 if (strict) {
1189 if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr)
1190 *strict = true;
1191 else
1192 *strict = false;
1193 }
1194
1195 return dst;
1196 }
1197
1198 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1199 .family = PF_INET,
1200 .obj_size = sizeof(struct tcp_request_sock),
1201 .rtx_syn_ack = tcp_rtx_synack,
1202 .send_ack = tcp_v4_reqsk_send_ack,
1203 .destructor = tcp_v4_reqsk_destructor,
1204 .send_reset = tcp_v4_send_reset,
1205 .syn_ack_timeout = tcp_syn_ack_timeout,
1206 };
1207
1208 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1209 .mss_clamp = TCP_MSS_DEFAULT,
1210 #ifdef CONFIG_TCP_MD5SIG
1211 .req_md5_lookup = tcp_v4_md5_lookup,
1212 .calc_md5_hash = tcp_v4_md5_hash_skb,
1213 #endif
1214 .init_req = tcp_v4_init_req,
1215 #ifdef CONFIG_SYN_COOKIES
1216 .cookie_init_seq = cookie_v4_init_sequence,
1217 #endif
1218 .route_req = tcp_v4_route_req,
1219 .init_seq = tcp_v4_init_sequence,
1220 .send_synack = tcp_v4_send_synack,
1221 .queue_hash_add = inet_csk_reqsk_queue_hash_add,
1222 };
1223
1224 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1225 {
1226 /* Never answer to SYNs send to broadcast or multicast */
1227 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1228 goto drop;
1229
1230 return tcp_conn_request(&tcp_request_sock_ops,
1231 &tcp_request_sock_ipv4_ops, sk, skb);
1232
1233 drop:
1234 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1235 return 0;
1236 }
1237 EXPORT_SYMBOL(tcp_v4_conn_request);
1238
1239
1240 /*
1241 * The three way handshake has completed - we got a valid synack -
1242 * now create the new socket.
1243 */
1244 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1245 struct request_sock *req,
1246 struct dst_entry *dst)
1247 {
1248 struct inet_request_sock *ireq;
1249 struct inet_sock *newinet;
1250 struct tcp_sock *newtp;
1251 struct sock *newsk;
1252 #ifdef CONFIG_TCP_MD5SIG
1253 struct tcp_md5sig_key *key;
1254 #endif
1255 struct ip_options_rcu *inet_opt;
1256
1257 if (sk_acceptq_is_full(sk))
1258 goto exit_overflow;
1259
1260 newsk = tcp_create_openreq_child(sk, req, skb);
1261 if (!newsk)
1262 goto exit_nonewsk;
1263
1264 newsk->sk_gso_type = SKB_GSO_TCPV4;
1265 inet_sk_rx_dst_set(newsk, skb);
1266
1267 newtp = tcp_sk(newsk);
1268 newinet = inet_sk(newsk);
1269 ireq = inet_rsk(req);
1270 sk_daddr_set(newsk, ireq->ir_rmt_addr);
1271 sk_rcv_saddr_set(newsk, ireq->ir_loc_addr);
1272 newinet->inet_saddr = ireq->ir_loc_addr;
1273 inet_opt = ireq->opt;
1274 rcu_assign_pointer(newinet->inet_opt, inet_opt);
1275 ireq->opt = NULL;
1276 newinet->mc_index = inet_iif(skb);
1277 newinet->mc_ttl = ip_hdr(skb)->ttl;
1278 newinet->rcv_tos = ip_hdr(skb)->tos;
1279 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1280 inet_set_txhash(newsk);
1281 if (inet_opt)
1282 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
1283 newinet->inet_id = newtp->write_seq ^ jiffies;
1284
1285 if (!dst) {
1286 dst = inet_csk_route_child_sock(sk, newsk, req);
1287 if (!dst)
1288 goto put_and_exit;
1289 } else {
1290 /* syncookie case : see end of cookie_v4_check() */
1291 }
1292 sk_setup_caps(newsk, dst);
1293
1294 tcp_ca_openreq_child(newsk, dst);
1295
1296 tcp_sync_mss(newsk, dst_mtu(dst));
1297 newtp->advmss = dst_metric_advmss(dst);
1298 if (tcp_sk(sk)->rx_opt.user_mss &&
1299 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1300 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1301
1302 tcp_initialize_rcv_mss(newsk);
1303
1304 #ifdef CONFIG_TCP_MD5SIG
1305 /* Copy over the MD5 key from the original socket */
1306 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr,
1307 AF_INET);
1308 if (key) {
1309 /*
1310 * We're using one, so create a matching key
1311 * on the newsk structure. If we fail to get
1312 * memory, then we end up not copying the key
1313 * across. Shucks.
1314 */
1315 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr,
1316 AF_INET, key->key, key->keylen, GFP_ATOMIC);
1317 sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1318 }
1319 #endif
1320
1321 if (__inet_inherit_port(sk, newsk) < 0)
1322 goto put_and_exit;
1323 __inet_hash_nolisten(newsk, NULL);
1324
1325 return newsk;
1326
1327 exit_overflow:
1328 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1329 exit_nonewsk:
1330 dst_release(dst);
1331 exit:
1332 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1333 return NULL;
1334 put_and_exit:
1335 inet_csk_prepare_forced_close(newsk);
1336 tcp_done(newsk);
1337 goto exit;
1338 }
1339 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1340
1341 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1342 {
1343 const struct tcphdr *th = tcp_hdr(skb);
1344 const struct iphdr *iph = ip_hdr(skb);
1345 struct request_sock *req;
1346 struct sock *nsk;
1347
1348 req = inet_csk_search_req(sk, th->source, iph->saddr, iph->daddr);
1349 if (req) {
1350 nsk = tcp_check_req(sk, skb, req, false);
1351 if (!nsk)
1352 reqsk_put(req);
1353 return nsk;
1354 }
1355
1356 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1357 th->source, iph->daddr, th->dest, inet_iif(skb));
1358
1359 if (nsk) {
1360 if (nsk->sk_state != TCP_TIME_WAIT) {
1361 bh_lock_sock(nsk);
1362 return nsk;
1363 }
1364 inet_twsk_put(inet_twsk(nsk));
1365 return NULL;
1366 }
1367
1368 #ifdef CONFIG_SYN_COOKIES
1369 if (!th->syn)
1370 sk = cookie_v4_check(sk, skb);
1371 #endif
1372 return sk;
1373 }
1374
1375 /* The socket must have it's spinlock held when we get
1376 * here.
1377 *
1378 * We have a potential double-lock case here, so even when
1379 * doing backlog processing we use the BH locking scheme.
1380 * This is because we cannot sleep with the original spinlock
1381 * held.
1382 */
1383 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1384 {
1385 struct sock *rsk;
1386
1387 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1388 struct dst_entry *dst = sk->sk_rx_dst;
1389
1390 sock_rps_save_rxhash(sk, skb);
1391 sk_mark_napi_id(sk, skb);
1392 if (dst) {
1393 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
1394 !dst->ops->check(dst, 0)) {
1395 dst_release(dst);
1396 sk->sk_rx_dst = NULL;
1397 }
1398 }
1399 tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len);
1400 return 0;
1401 }
1402
1403 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1404 goto csum_err;
1405
1406 if (sk->sk_state == TCP_LISTEN) {
1407 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1408 if (!nsk)
1409 goto discard;
1410
1411 if (nsk != sk) {
1412 sock_rps_save_rxhash(nsk, skb);
1413 sk_mark_napi_id(sk, skb);
1414 if (tcp_child_process(sk, nsk, skb)) {
1415 rsk = nsk;
1416 goto reset;
1417 }
1418 return 0;
1419 }
1420 } else
1421 sock_rps_save_rxhash(sk, skb);
1422
1423 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1424 rsk = sk;
1425 goto reset;
1426 }
1427 return 0;
1428
1429 reset:
1430 tcp_v4_send_reset(rsk, skb);
1431 discard:
1432 kfree_skb(skb);
1433 /* Be careful here. If this function gets more complicated and
1434 * gcc suffers from register pressure on the x86, sk (in %ebx)
1435 * might be destroyed here. This current version compiles correctly,
1436 * but you have been warned.
1437 */
1438 return 0;
1439
1440 csum_err:
1441 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
1442 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1443 goto discard;
1444 }
1445 EXPORT_SYMBOL(tcp_v4_do_rcv);
1446
1447 void tcp_v4_early_demux(struct sk_buff *skb)
1448 {
1449 const struct iphdr *iph;
1450 const struct tcphdr *th;
1451 struct sock *sk;
1452
1453 if (skb->pkt_type != PACKET_HOST)
1454 return;
1455
1456 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
1457 return;
1458
1459 iph = ip_hdr(skb);
1460 th = tcp_hdr(skb);
1461
1462 if (th->doff < sizeof(struct tcphdr) / 4)
1463 return;
1464
1465 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
1466 iph->saddr, th->source,
1467 iph->daddr, ntohs(th->dest),
1468 skb->skb_iif);
1469 if (sk) {
1470 skb->sk = sk;
1471 skb->destructor = sock_edemux;
1472 if (sk_fullsock(sk)) {
1473 struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
1474
1475 if (dst)
1476 dst = dst_check(dst, 0);
1477 if (dst &&
1478 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
1479 skb_dst_set_noref(skb, dst);
1480 }
1481 }
1482 }
1483
1484 /* Packet is added to VJ-style prequeue for processing in process
1485 * context, if a reader task is waiting. Apparently, this exciting
1486 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1487 * failed somewhere. Latency? Burstiness? Well, at least now we will
1488 * see, why it failed. 8)8) --ANK
1489 *
1490 */
1491 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1492 {
1493 struct tcp_sock *tp = tcp_sk(sk);
1494
1495 if (sysctl_tcp_low_latency || !tp->ucopy.task)
1496 return false;
1497
1498 if (skb->len <= tcp_hdrlen(skb) &&
1499 skb_queue_len(&tp->ucopy.prequeue) == 0)
1500 return false;
1501
1502 /* Before escaping RCU protected region, we need to take care of skb
1503 * dst. Prequeue is only enabled for established sockets.
1504 * For such sockets, we might need the skb dst only to set sk->sk_rx_dst
1505 * Instead of doing full sk_rx_dst validity here, let's perform
1506 * an optimistic check.
1507 */
1508 if (likely(sk->sk_rx_dst))
1509 skb_dst_drop(skb);
1510 else
1511 skb_dst_force(skb);
1512
1513 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1514 tp->ucopy.memory += skb->truesize;
1515 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1516 struct sk_buff *skb1;
1517
1518 BUG_ON(sock_owned_by_user(sk));
1519
1520 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1521 sk_backlog_rcv(sk, skb1);
1522 NET_INC_STATS_BH(sock_net(sk),
1523 LINUX_MIB_TCPPREQUEUEDROPPED);
1524 }
1525
1526 tp->ucopy.memory = 0;
1527 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1528 wake_up_interruptible_sync_poll(sk_sleep(sk),
1529 POLLIN | POLLRDNORM | POLLRDBAND);
1530 if (!inet_csk_ack_scheduled(sk))
1531 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1532 (3 * tcp_rto_min(sk)) / 4,
1533 TCP_RTO_MAX);
1534 }
1535 return true;
1536 }
1537 EXPORT_SYMBOL(tcp_prequeue);
1538
1539 /*
1540 * From tcp_input.c
1541 */
1542
1543 int tcp_v4_rcv(struct sk_buff *skb)
1544 {
1545 const struct iphdr *iph;
1546 const struct tcphdr *th;
1547 struct sock *sk;
1548 int ret;
1549 struct net *net = dev_net(skb->dev);
1550
1551 if (skb->pkt_type != PACKET_HOST)
1552 goto discard_it;
1553
1554 /* Count it even if it's bad */
1555 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1556
1557 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1558 goto discard_it;
1559
1560 th = tcp_hdr(skb);
1561
1562 if (th->doff < sizeof(struct tcphdr) / 4)
1563 goto bad_packet;
1564 if (!pskb_may_pull(skb, th->doff * 4))
1565 goto discard_it;
1566
1567 /* An explanation is required here, I think.
1568 * Packet length and doff are validated by header prediction,
1569 * provided case of th->doff==0 is eliminated.
1570 * So, we defer the checks. */
1571
1572 if (skb_checksum_init(skb, IPPROTO_TCP, inet_compute_pseudo))
1573 goto csum_error;
1574
1575 th = tcp_hdr(skb);
1576 iph = ip_hdr(skb);
1577 /* This is tricky : We move IPCB at its correct location into TCP_SKB_CB()
1578 * barrier() makes sure compiler wont play fool^Waliasing games.
1579 */
1580 memmove(&TCP_SKB_CB(skb)->header.h4, IPCB(skb),
1581 sizeof(struct inet_skb_parm));
1582 barrier();
1583
1584 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1585 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1586 skb->len - th->doff * 4);
1587 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1588 TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
1589 TCP_SKB_CB(skb)->tcp_tw_isn = 0;
1590 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
1591 TCP_SKB_CB(skb)->sacked = 0;
1592
1593 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1594 if (!sk)
1595 goto no_tcp_socket;
1596
1597 process:
1598 if (sk->sk_state == TCP_TIME_WAIT)
1599 goto do_time_wait;
1600
1601 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
1602 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1603 goto discard_and_relse;
1604 }
1605
1606 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1607 goto discard_and_relse;
1608
1609 #ifdef CONFIG_TCP_MD5SIG
1610 /*
1611 * We really want to reject the packet as early as possible
1612 * if:
1613 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1614 * o There is an MD5 option and we're not expecting one
1615 */
1616 if (tcp_v4_inbound_md5_hash(sk, skb))
1617 goto discard_and_relse;
1618 #endif
1619
1620 nf_reset(skb);
1621
1622 if (sk_filter(sk, skb))
1623 goto discard_and_relse;
1624
1625 sk_incoming_cpu_update(sk);
1626 skb->dev = NULL;
1627
1628 bh_lock_sock_nested(sk);
1629 ret = 0;
1630 if (!sock_owned_by_user(sk)) {
1631 if (!tcp_prequeue(sk, skb))
1632 ret = tcp_v4_do_rcv(sk, skb);
1633 } else if (unlikely(sk_add_backlog(sk, skb,
1634 sk->sk_rcvbuf + sk->sk_sndbuf))) {
1635 bh_unlock_sock(sk);
1636 NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
1637 goto discard_and_relse;
1638 }
1639 bh_unlock_sock(sk);
1640
1641 sock_put(sk);
1642
1643 return ret;
1644
1645 no_tcp_socket:
1646 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
1647 goto discard_it;
1648
1649 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
1650 csum_error:
1651 TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
1652 bad_packet:
1653 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
1654 } else {
1655 tcp_v4_send_reset(NULL, skb);
1656 }
1657
1658 discard_it:
1659 /* Discard frame. */
1660 kfree_skb(skb);
1661 return 0;
1662
1663 discard_and_relse:
1664 sock_put(sk);
1665 goto discard_it;
1666
1667 do_time_wait:
1668 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1669 inet_twsk_put(inet_twsk(sk));
1670 goto discard_it;
1671 }
1672
1673 if (skb->len < (th->doff << 2)) {
1674 inet_twsk_put(inet_twsk(sk));
1675 goto bad_packet;
1676 }
1677 if (tcp_checksum_complete(skb)) {
1678 inet_twsk_put(inet_twsk(sk));
1679 goto csum_error;
1680 }
1681 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
1682 case TCP_TW_SYN: {
1683 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
1684 &tcp_hashinfo,
1685 iph->saddr, th->source,
1686 iph->daddr, th->dest,
1687 inet_iif(skb));
1688 if (sk2) {
1689 inet_twsk_deschedule(inet_twsk(sk));
1690 inet_twsk_put(inet_twsk(sk));
1691 sk = sk2;
1692 goto process;
1693 }
1694 /* Fall through to ACK */
1695 }
1696 case TCP_TW_ACK:
1697 tcp_v4_timewait_ack(sk, skb);
1698 break;
1699 case TCP_TW_RST:
1700 goto no_tcp_socket;
1701 case TCP_TW_SUCCESS:;
1702 }
1703 goto discard_it;
1704 }
1705
1706 static struct timewait_sock_ops tcp_timewait_sock_ops = {
1707 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
1708 .twsk_unique = tcp_twsk_unique,
1709 .twsk_destructor= tcp_twsk_destructor,
1710 };
1711
1712 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
1713 {
1714 struct dst_entry *dst = skb_dst(skb);
1715
1716 if (dst) {
1717 dst_hold(dst);
1718 sk->sk_rx_dst = dst;
1719 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
1720 }
1721 }
1722 EXPORT_SYMBOL(inet_sk_rx_dst_set);
1723
1724 const struct inet_connection_sock_af_ops ipv4_specific = {
1725 .queue_xmit = ip_queue_xmit,
1726 .send_check = tcp_v4_send_check,
1727 .rebuild_header = inet_sk_rebuild_header,
1728 .sk_rx_dst_set = inet_sk_rx_dst_set,
1729 .conn_request = tcp_v4_conn_request,
1730 .syn_recv_sock = tcp_v4_syn_recv_sock,
1731 .net_header_len = sizeof(struct iphdr),
1732 .setsockopt = ip_setsockopt,
1733 .getsockopt = ip_getsockopt,
1734 .addr2sockaddr = inet_csk_addr2sockaddr,
1735 .sockaddr_len = sizeof(struct sockaddr_in),
1736 .bind_conflict = inet_csk_bind_conflict,
1737 #ifdef CONFIG_COMPAT
1738 .compat_setsockopt = compat_ip_setsockopt,
1739 .compat_getsockopt = compat_ip_getsockopt,
1740 #endif
1741 .mtu_reduced = tcp_v4_mtu_reduced,
1742 };
1743 EXPORT_SYMBOL(ipv4_specific);
1744
1745 #ifdef CONFIG_TCP_MD5SIG
1746 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
1747 .md5_lookup = tcp_v4_md5_lookup,
1748 .calc_md5_hash = tcp_v4_md5_hash_skb,
1749 .md5_parse = tcp_v4_parse_md5_keys,
1750 };
1751 #endif
1752
1753 /* NOTE: A lot of things set to zero explicitly by call to
1754 * sk_alloc() so need not be done here.
1755 */
1756 static int tcp_v4_init_sock(struct sock *sk)
1757 {
1758 struct inet_connection_sock *icsk = inet_csk(sk);
1759
1760 tcp_init_sock(sk);
1761
1762 icsk->icsk_af_ops = &ipv4_specific;
1763
1764 #ifdef CONFIG_TCP_MD5SIG
1765 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
1766 #endif
1767
1768 return 0;
1769 }
1770
1771 void tcp_v4_destroy_sock(struct sock *sk)
1772 {
1773 struct tcp_sock *tp = tcp_sk(sk);
1774
1775 tcp_clear_xmit_timers(sk);
1776
1777 tcp_cleanup_congestion_control(sk);
1778
1779 /* Cleanup up the write buffer. */
1780 tcp_write_queue_purge(sk);
1781
1782 /* Cleans up our, hopefully empty, out_of_order_queue. */
1783 __skb_queue_purge(&tp->out_of_order_queue);
1784
1785 #ifdef CONFIG_TCP_MD5SIG
1786 /* Clean up the MD5 key list, if any */
1787 if (tp->md5sig_info) {
1788 tcp_clear_md5_list(sk);
1789 kfree_rcu(tp->md5sig_info, rcu);
1790 tp->md5sig_info = NULL;
1791 }
1792 #endif
1793
1794 /* Clean prequeue, it must be empty really */
1795 __skb_queue_purge(&tp->ucopy.prequeue);
1796
1797 /* Clean up a referenced TCP bind bucket. */
1798 if (inet_csk(sk)->icsk_bind_hash)
1799 inet_put_port(sk);
1800
1801 BUG_ON(tp->fastopen_rsk);
1802
1803 /* If socket is aborted during connect operation */
1804 tcp_free_fastopen_req(tp);
1805
1806 sk_sockets_allocated_dec(sk);
1807 sock_release_memcg(sk);
1808 }
1809 EXPORT_SYMBOL(tcp_v4_destroy_sock);
1810
1811 #ifdef CONFIG_PROC_FS
1812 /* Proc filesystem TCP sock list dumping. */
1813
1814 /*
1815 * Get next listener socket follow cur. If cur is NULL, get first socket
1816 * starting from bucket given in st->bucket; when st->bucket is zero the
1817 * very first socket in the hash table is returned.
1818 */
1819 static void *listening_get_next(struct seq_file *seq, void *cur)
1820 {
1821 struct inet_connection_sock *icsk;
1822 struct hlist_nulls_node *node;
1823 struct sock *sk = cur;
1824 struct inet_listen_hashbucket *ilb;
1825 struct tcp_iter_state *st = seq->private;
1826 struct net *net = seq_file_net(seq);
1827
1828 if (!sk) {
1829 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1830 spin_lock_bh(&ilb->lock);
1831 sk = sk_nulls_head(&ilb->head);
1832 st->offset = 0;
1833 goto get_sk;
1834 }
1835 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1836 ++st->num;
1837 ++st->offset;
1838
1839 if (st->state == TCP_SEQ_STATE_OPENREQ) {
1840 struct request_sock *req = cur;
1841
1842 icsk = inet_csk(st->syn_wait_sk);
1843 req = req->dl_next;
1844 while (1) {
1845 while (req) {
1846 if (req->rsk_ops->family == st->family) {
1847 cur = req;
1848 goto out;
1849 }
1850 req = req->dl_next;
1851 }
1852 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
1853 break;
1854 get_req:
1855 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
1856 }
1857 sk = sk_nulls_next(st->syn_wait_sk);
1858 st->state = TCP_SEQ_STATE_LISTENING;
1859 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1860 } else {
1861 icsk = inet_csk(sk);
1862 spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1863 if (reqsk_queue_len(&icsk->icsk_accept_queue))
1864 goto start_req;
1865 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1866 sk = sk_nulls_next(sk);
1867 }
1868 get_sk:
1869 sk_nulls_for_each_from(sk, node) {
1870 if (!net_eq(sock_net(sk), net))
1871 continue;
1872 if (sk->sk_family == st->family) {
1873 cur = sk;
1874 goto out;
1875 }
1876 icsk = inet_csk(sk);
1877 spin_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1878 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
1879 start_req:
1880 st->uid = sock_i_uid(sk);
1881 st->syn_wait_sk = sk;
1882 st->state = TCP_SEQ_STATE_OPENREQ;
1883 st->sbucket = 0;
1884 goto get_req;
1885 }
1886 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
1887 }
1888 spin_unlock_bh(&ilb->lock);
1889 st->offset = 0;
1890 if (++st->bucket < INET_LHTABLE_SIZE) {
1891 ilb = &tcp_hashinfo.listening_hash[st->bucket];
1892 spin_lock_bh(&ilb->lock);
1893 sk = sk_nulls_head(&ilb->head);
1894 goto get_sk;
1895 }
1896 cur = NULL;
1897 out:
1898 return cur;
1899 }
1900
1901 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
1902 {
1903 struct tcp_iter_state *st = seq->private;
1904 void *rc;
1905
1906 st->bucket = 0;
1907 st->offset = 0;
1908 rc = listening_get_next(seq, NULL);
1909
1910 while (rc && *pos) {
1911 rc = listening_get_next(seq, rc);
1912 --*pos;
1913 }
1914 return rc;
1915 }
1916
1917 static inline bool empty_bucket(const struct tcp_iter_state *st)
1918 {
1919 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain);
1920 }
1921
1922 /*
1923 * Get first established socket starting from bucket given in st->bucket.
1924 * If st->bucket is zero, the very first socket in the hash is returned.
1925 */
1926 static void *established_get_first(struct seq_file *seq)
1927 {
1928 struct tcp_iter_state *st = seq->private;
1929 struct net *net = seq_file_net(seq);
1930 void *rc = NULL;
1931
1932 st->offset = 0;
1933 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
1934 struct sock *sk;
1935 struct hlist_nulls_node *node;
1936 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
1937
1938 /* Lockless fast path for the common case of empty buckets */
1939 if (empty_bucket(st))
1940 continue;
1941
1942 spin_lock_bh(lock);
1943 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
1944 if (sk->sk_family != st->family ||
1945 !net_eq(sock_net(sk), net)) {
1946 continue;
1947 }
1948 rc = sk;
1949 goto out;
1950 }
1951 spin_unlock_bh(lock);
1952 }
1953 out:
1954 return rc;
1955 }
1956
1957 static void *established_get_next(struct seq_file *seq, void *cur)
1958 {
1959 struct sock *sk = cur;
1960 struct hlist_nulls_node *node;
1961 struct tcp_iter_state *st = seq->private;
1962 struct net *net = seq_file_net(seq);
1963
1964 ++st->num;
1965 ++st->offset;
1966
1967 sk = sk_nulls_next(sk);
1968
1969 sk_nulls_for_each_from(sk, node) {
1970 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
1971 return sk;
1972 }
1973
1974 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
1975 ++st->bucket;
1976 return established_get_first(seq);
1977 }
1978
1979 static void *established_get_idx(struct seq_file *seq, loff_t pos)
1980 {
1981 struct tcp_iter_state *st = seq->private;
1982 void *rc;
1983
1984 st->bucket = 0;
1985 rc = established_get_first(seq);
1986
1987 while (rc && pos) {
1988 rc = established_get_next(seq, rc);
1989 --pos;
1990 }
1991 return rc;
1992 }
1993
1994 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
1995 {
1996 void *rc;
1997 struct tcp_iter_state *st = seq->private;
1998
1999 st->state = TCP_SEQ_STATE_LISTENING;
2000 rc = listening_get_idx(seq, &pos);
2001
2002 if (!rc) {
2003 st->state = TCP_SEQ_STATE_ESTABLISHED;
2004 rc = established_get_idx(seq, pos);
2005 }
2006
2007 return rc;
2008 }
2009
2010 static void *tcp_seek_last_pos(struct seq_file *seq)
2011 {
2012 struct tcp_iter_state *st = seq->private;
2013 int offset = st->offset;
2014 int orig_num = st->num;
2015 void *rc = NULL;
2016
2017 switch (st->state) {
2018 case TCP_SEQ_STATE_OPENREQ:
2019 case TCP_SEQ_STATE_LISTENING:
2020 if (st->bucket >= INET_LHTABLE_SIZE)
2021 break;
2022 st->state = TCP_SEQ_STATE_LISTENING;
2023 rc = listening_get_next(seq, NULL);
2024 while (offset-- && rc)
2025 rc = listening_get_next(seq, rc);
2026 if (rc)
2027 break;
2028 st->bucket = 0;
2029 st->state = TCP_SEQ_STATE_ESTABLISHED;
2030 /* Fallthrough */
2031 case TCP_SEQ_STATE_ESTABLISHED:
2032 if (st->bucket > tcp_hashinfo.ehash_mask)
2033 break;
2034 rc = established_get_first(seq);
2035 while (offset-- && rc)
2036 rc = established_get_next(seq, rc);
2037 }
2038
2039 st->num = orig_num;
2040
2041 return rc;
2042 }
2043
2044 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2045 {
2046 struct tcp_iter_state *st = seq->private;
2047 void *rc;
2048
2049 if (*pos && *pos == st->last_pos) {
2050 rc = tcp_seek_last_pos(seq);
2051 if (rc)
2052 goto out;
2053 }
2054
2055 st->state = TCP_SEQ_STATE_LISTENING;
2056 st->num = 0;
2057 st->bucket = 0;
2058 st->offset = 0;
2059 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2060
2061 out:
2062 st->last_pos = *pos;
2063 return rc;
2064 }
2065
2066 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2067 {
2068 struct tcp_iter_state *st = seq->private;
2069 void *rc = NULL;
2070
2071 if (v == SEQ_START_TOKEN) {
2072 rc = tcp_get_idx(seq, 0);
2073 goto out;
2074 }
2075
2076 switch (st->state) {
2077 case TCP_SEQ_STATE_OPENREQ:
2078 case TCP_SEQ_STATE_LISTENING:
2079 rc = listening_get_next(seq, v);
2080 if (!rc) {
2081 st->state = TCP_SEQ_STATE_ESTABLISHED;
2082 st->bucket = 0;
2083 st->offset = 0;
2084 rc = established_get_first(seq);
2085 }
2086 break;
2087 case TCP_SEQ_STATE_ESTABLISHED:
2088 rc = established_get_next(seq, v);
2089 break;
2090 }
2091 out:
2092 ++*pos;
2093 st->last_pos = *pos;
2094 return rc;
2095 }
2096
2097 static void tcp_seq_stop(struct seq_file *seq, void *v)
2098 {
2099 struct tcp_iter_state *st = seq->private;
2100
2101 switch (st->state) {
2102 case TCP_SEQ_STATE_OPENREQ:
2103 if (v) {
2104 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2105 spin_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2106 }
2107 case TCP_SEQ_STATE_LISTENING:
2108 if (v != SEQ_START_TOKEN)
2109 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2110 break;
2111 case TCP_SEQ_STATE_ESTABLISHED:
2112 if (v)
2113 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2114 break;
2115 }
2116 }
2117
2118 int tcp_seq_open(struct inode *inode, struct file *file)
2119 {
2120 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode);
2121 struct tcp_iter_state *s;
2122 int err;
2123
2124 err = seq_open_net(inode, file, &afinfo->seq_ops,
2125 sizeof(struct tcp_iter_state));
2126 if (err < 0)
2127 return err;
2128
2129 s = ((struct seq_file *)file->private_data)->private;
2130 s->family = afinfo->family;
2131 s->last_pos = 0;
2132 return 0;
2133 }
2134 EXPORT_SYMBOL(tcp_seq_open);
2135
2136 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2137 {
2138 int rc = 0;
2139 struct proc_dir_entry *p;
2140
2141 afinfo->seq_ops.start = tcp_seq_start;
2142 afinfo->seq_ops.next = tcp_seq_next;
2143 afinfo->seq_ops.stop = tcp_seq_stop;
2144
2145 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2146 afinfo->seq_fops, afinfo);
2147 if (!p)
2148 rc = -ENOMEM;
2149 return rc;
2150 }
2151 EXPORT_SYMBOL(tcp_proc_register);
2152
2153 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2154 {
2155 remove_proc_entry(afinfo->name, net->proc_net);
2156 }
2157 EXPORT_SYMBOL(tcp_proc_unregister);
2158
2159 static void get_openreq4(const struct request_sock *req,
2160 struct seq_file *f, int i, kuid_t uid)
2161 {
2162 const struct inet_request_sock *ireq = inet_rsk(req);
2163 long delta = req->rsk_timer.expires - jiffies;
2164
2165 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2166 " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK",
2167 i,
2168 ireq->ir_loc_addr,
2169 ireq->ir_num,
2170 ireq->ir_rmt_addr,
2171 ntohs(ireq->ir_rmt_port),
2172 TCP_SYN_RECV,
2173 0, 0, /* could print option size, but that is af dependent. */
2174 1, /* timers active (only the expire timer) */
2175 jiffies_delta_to_clock_t(delta),
2176 req->num_timeout,
2177 from_kuid_munged(seq_user_ns(f), uid),
2178 0, /* non standard timer */
2179 0, /* open_requests have no inode */
2180 0,
2181 req);
2182 }
2183
2184 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
2185 {
2186 int timer_active;
2187 unsigned long timer_expires;
2188 const struct tcp_sock *tp = tcp_sk(sk);
2189 const struct inet_connection_sock *icsk = inet_csk(sk);
2190 const struct inet_sock *inet = inet_sk(sk);
2191 struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;
2192 __be32 dest = inet->inet_daddr;
2193 __be32 src = inet->inet_rcv_saddr;
2194 __u16 destp = ntohs(inet->inet_dport);
2195 __u16 srcp = ntohs(inet->inet_sport);
2196 int rx_queue;
2197
2198 if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
2199 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
2200 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
2201 timer_active = 1;
2202 timer_expires = icsk->icsk_timeout;
2203 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2204 timer_active = 4;
2205 timer_expires = icsk->icsk_timeout;
2206 } else if (timer_pending(&sk->sk_timer)) {
2207 timer_active = 2;
2208 timer_expires = sk->sk_timer.expires;
2209 } else {
2210 timer_active = 0;
2211 timer_expires = jiffies;
2212 }
2213
2214 if (sk->sk_state == TCP_LISTEN)
2215 rx_queue = sk->sk_ack_backlog;
2216 else
2217 /*
2218 * because we dont lock socket, we might find a transient negative value
2219 */
2220 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
2221
2222 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2223 "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
2224 i, src, srcp, dest, destp, sk->sk_state,
2225 tp->write_seq - tp->snd_una,
2226 rx_queue,
2227 timer_active,
2228 jiffies_delta_to_clock_t(timer_expires - jiffies),
2229 icsk->icsk_retransmits,
2230 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
2231 icsk->icsk_probes_out,
2232 sock_i_ino(sk),
2233 atomic_read(&sk->sk_refcnt), sk,
2234 jiffies_to_clock_t(icsk->icsk_rto),
2235 jiffies_to_clock_t(icsk->icsk_ack.ato),
2236 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2237 tp->snd_cwnd,
2238 sk->sk_state == TCP_LISTEN ?
2239 (fastopenq ? fastopenq->max_qlen : 0) :
2240 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh));
2241 }
2242
2243 static void get_timewait4_sock(const struct inet_timewait_sock *tw,
2244 struct seq_file *f, int i)
2245 {
2246 long delta = tw->tw_timer.expires - jiffies;
2247 __be32 dest, src;
2248 __u16 destp, srcp;
2249
2250 dest = tw->tw_daddr;
2251 src = tw->tw_rcv_saddr;
2252 destp = ntohs(tw->tw_dport);
2253 srcp = ntohs(tw->tw_sport);
2254
2255 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2256 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",
2257 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2258 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
2259 atomic_read(&tw->tw_refcnt), tw);
2260 }
2261
2262 #define TMPSZ 150
2263
2264 static int tcp4_seq_show(struct seq_file *seq, void *v)
2265 {
2266 struct tcp_iter_state *st;
2267 struct sock *sk = v;
2268
2269 seq_setwidth(seq, TMPSZ - 1);
2270 if (v == SEQ_START_TOKEN) {
2271 seq_puts(seq, " sl local_address rem_address st tx_queue "
2272 "rx_queue tr tm->when retrnsmt uid timeout "
2273 "inode");
2274 goto out;
2275 }
2276 st = seq->private;
2277
2278 switch (st->state) {
2279 case TCP_SEQ_STATE_LISTENING:
2280 case TCP_SEQ_STATE_ESTABLISHED:
2281 if (sk->sk_state == TCP_TIME_WAIT)
2282 get_timewait4_sock(v, seq, st->num);
2283 else
2284 get_tcp4_sock(v, seq, st->num);
2285 break;
2286 case TCP_SEQ_STATE_OPENREQ:
2287 get_openreq4(v, seq, st->num, st->uid);
2288 break;
2289 }
2290 out:
2291 seq_pad(seq, '\n');
2292 return 0;
2293 }
2294
2295 static const struct file_operations tcp_afinfo_seq_fops = {
2296 .owner = THIS_MODULE,
2297 .open = tcp_seq_open,
2298 .read = seq_read,
2299 .llseek = seq_lseek,
2300 .release = seq_release_net
2301 };
2302
2303 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2304 .name = "tcp",
2305 .family = AF_INET,
2306 .seq_fops = &tcp_afinfo_seq_fops,
2307 .seq_ops = {
2308 .show = tcp4_seq_show,
2309 },
2310 };
2311
2312 static int __net_init tcp4_proc_init_net(struct net *net)
2313 {
2314 return tcp_proc_register(net, &tcp4_seq_afinfo);
2315 }
2316
2317 static void __net_exit tcp4_proc_exit_net(struct net *net)
2318 {
2319 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2320 }
2321
2322 static struct pernet_operations tcp4_net_ops = {
2323 .init = tcp4_proc_init_net,
2324 .exit = tcp4_proc_exit_net,
2325 };
2326
2327 int __init tcp4_proc_init(void)
2328 {
2329 return register_pernet_subsys(&tcp4_net_ops);
2330 }
2331
2332 void tcp4_proc_exit(void)
2333 {
2334 unregister_pernet_subsys(&tcp4_net_ops);
2335 }
2336 #endif /* CONFIG_PROC_FS */
2337
2338 struct proto tcp_prot = {
2339 .name = "TCP",
2340 .owner = THIS_MODULE,
2341 .close = tcp_close,
2342 .connect = tcp_v4_connect,
2343 .disconnect = tcp_disconnect,
2344 .accept = inet_csk_accept,
2345 .ioctl = tcp_ioctl,
2346 .init = tcp_v4_init_sock,
2347 .destroy = tcp_v4_destroy_sock,
2348 .shutdown = tcp_shutdown,
2349 .setsockopt = tcp_setsockopt,
2350 .getsockopt = tcp_getsockopt,
2351 .recvmsg = tcp_recvmsg,
2352 .sendmsg = tcp_sendmsg,
2353 .sendpage = tcp_sendpage,
2354 .backlog_rcv = tcp_v4_do_rcv,
2355 .release_cb = tcp_release_cb,
2356 .hash = inet_hash,
2357 .unhash = inet_unhash,
2358 .get_port = inet_csk_get_port,
2359 .enter_memory_pressure = tcp_enter_memory_pressure,
2360 .stream_memory_free = tcp_stream_memory_free,
2361 .sockets_allocated = &tcp_sockets_allocated,
2362 .orphan_count = &tcp_orphan_count,
2363 .memory_allocated = &tcp_memory_allocated,
2364 .memory_pressure = &tcp_memory_pressure,
2365 .sysctl_mem = sysctl_tcp_mem,
2366 .sysctl_wmem = sysctl_tcp_wmem,
2367 .sysctl_rmem = sysctl_tcp_rmem,
2368 .max_header = MAX_TCP_HEADER,
2369 .obj_size = sizeof(struct tcp_sock),
2370 .slab_flags = SLAB_DESTROY_BY_RCU,
2371 .twsk_prot = &tcp_timewait_sock_ops,
2372 .rsk_prot = &tcp_request_sock_ops,
2373 .h.hashinfo = &tcp_hashinfo,
2374 .no_autobind = true,
2375 #ifdef CONFIG_COMPAT
2376 .compat_setsockopt = compat_tcp_setsockopt,
2377 .compat_getsockopt = compat_tcp_getsockopt,
2378 #endif
2379 #ifdef CONFIG_MEMCG_KMEM
2380 .init_cgroup = tcp_init_cgroup,
2381 .destroy_cgroup = tcp_destroy_cgroup,
2382 .proto_cgroup = tcp_proto_cgroup,
2383 #endif
2384 };
2385 EXPORT_SYMBOL(tcp_prot);
2386
2387 static void __net_exit tcp_sk_exit(struct net *net)
2388 {
2389 int cpu;
2390
2391 for_each_possible_cpu(cpu)
2392 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu));
2393 free_percpu(net->ipv4.tcp_sk);
2394 }
2395
2396 static int __net_init tcp_sk_init(struct net *net)
2397 {
2398 int res, cpu;
2399
2400 net->ipv4.tcp_sk = alloc_percpu(struct sock *);
2401 if (!net->ipv4.tcp_sk)
2402 return -ENOMEM;
2403
2404 for_each_possible_cpu(cpu) {
2405 struct sock *sk;
2406
2407 res = inet_ctl_sock_create(&sk, PF_INET, SOCK_RAW,
2408 IPPROTO_TCP, net);
2409 if (res)
2410 goto fail;
2411 *per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk;
2412 }
2413 net->ipv4.sysctl_tcp_ecn = 2;
2414 net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS;
2415 net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
2416 net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;
2417 return 0;
2418
2419 fail:
2420 tcp_sk_exit(net);
2421
2422 return res;
2423 }
2424
2425 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
2426 {
2427 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2428 }
2429
2430 static struct pernet_operations __net_initdata tcp_sk_ops = {
2431 .init = tcp_sk_init,
2432 .exit = tcp_sk_exit,
2433 .exit_batch = tcp_sk_exit_batch,
2434 };
2435
2436 void __init tcp_v4_init(void)
2437 {
2438 inet_hashinfo_init(&tcp_hashinfo);
2439 if (register_pernet_subsys(&tcp_sk_ops))
2440 panic("Failed to create the TCP control socket.\n");
2441 }