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Linux/net/ipv4/tcp_ipv4.c

  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              Implementation of the Transmission Control Protocol(TCP).
  7  *
  8  *              IPv4 specific functions
  9  *
 10  *
 11  *              code split from:
 12  *              linux/ipv4/tcp.c
 13  *              linux/ipv4/tcp_input.c
 14  *              linux/ipv4/tcp_output.c
 15  *
 16  *              See tcp.c for author information
 17  *
 18  *      This program is free software; you can redistribute it and/or
 19  *      modify it under the terms of the GNU General Public License
 20  *      as published by the Free Software Foundation; either version
 21  *      2 of the License, or (at your option) any later version.
 22  */
 23 
 24 /*
 25  * Changes:
 26  *              David S. Miller :       New socket lookup architecture.
 27  *                                      This code is dedicated to John Dyson.
 28  *              David S. Miller :       Change semantics of established hash,
 29  *                                      half is devoted to TIME_WAIT sockets
 30  *                                      and the rest go in the other half.
 31  *              Andi Kleen :            Add support for syncookies and fixed
 32  *                                      some bugs: ip options weren't passed to
 33  *                                      the TCP layer, missed a check for an
 34  *                                      ACK bit.
 35  *              Andi Kleen :            Implemented fast path mtu discovery.
 36  *                                      Fixed many serious bugs in the
 37  *                                      request_sock handling and moved
 38  *                                      most of it into the af independent code.
 39  *                                      Added tail drop and some other bugfixes.
 40  *                                      Added new listen semantics.
 41  *              Mike McLagan    :       Routing by source
 42  *      Juan Jose Ciarlante:            ip_dynaddr bits
 43  *              Andi Kleen:             various fixes.
 44  *      Vitaly E. Lavrov        :       Transparent proxy revived after year
 45  *                                      coma.
 46  *      Andi Kleen              :       Fix new listen.
 47  *      Andi Kleen              :       Fix accept error reporting.
 48  *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
 49  *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
 50  *                                      a single port at the same time.
 51  */
 52 
 53 #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 }
2442 

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