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.
6 * Implementation of the Transmission Control Protocol(TCP).
8 * IPv4 specific functions
13 * linux/ipv4/tcp_input.c
14 * linux/ipv4/tcp_output.c
16 * See tcp.c for author information
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.
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
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
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.
53 #define pr_fmt(fmt) "TCP: " fmt
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>
66 #include <net/net_namespace.h>
68 #include <net/inet_hashtables.h>
70 #include <net/transp_v6.h>
72 #include <net/inet_common.h>
73 #include <net/timewait_sock.h>
75 #include <net/netdma.h>
76 #include <net/secure_seq.h>
77 #include <net/tcp_memcontrol.h>
78 #include <net/busy_poll.h>
80 #include <linux/inet.h>
81 #include <linux/ipv6.h>
82 #include <linux/stddef.h>
83 #include <linux/proc_fs.h>
84 #include <linux/seq_file.h>
86 #include <linux/crypto.h>
87 #include <linux/scatterlist.h>
89 int sysctl_tcp_tw_reuse __read_mostly;
90 int sysctl_tcp_low_latency __read_mostly;
91 EXPORT_SYMBOL(sysctl_tcp_low_latency);
94 #ifdef CONFIG_TCP_MD5SIG
95 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
96 __be32 daddr, __be32 saddr, const struct tcphdr *th);
99 struct inet_hashinfo tcp_hashinfo;
100 EXPORT_SYMBOL(tcp_hashinfo);
102 static inline __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
104 return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
107 tcp_hdr(skb)->source);
110 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
112 const struct tcp_timewait_sock *tcptw = tcp_twsk(sktw);
113 struct tcp_sock *tp = tcp_sk(sk);
115 /* With PAWS, it is safe from the viewpoint
116 of data integrity. Even without PAWS it is safe provided sequence
117 spaces do not overlap i.e. at data rates <= 80Mbit/sec.
119 Actually, the idea is close to VJ's one, only timestamp cache is
120 held not per host, but per port pair and TW bucket is used as state
123 If TW bucket has been already destroyed we fall back to VJ's scheme
124 and use initial timestamp retrieved from peer table.
126 if (tcptw->tw_ts_recent_stamp &&
127 (twp == NULL || (sysctl_tcp_tw_reuse &&
128 get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
129 tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
130 if (tp->write_seq == 0)
132 tp->rx_opt.ts_recent = tcptw->tw_ts_recent;
133 tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
140 EXPORT_SYMBOL_GPL(tcp_twsk_unique);
142 /* This will initiate an outgoing connection. */
143 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
145 struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
146 struct inet_sock *inet = inet_sk(sk);
147 struct tcp_sock *tp = tcp_sk(sk);
148 __be16 orig_sport, orig_dport;
149 __be32 daddr, nexthop;
153 struct ip_options_rcu *inet_opt;
155 if (addr_len < sizeof(struct sockaddr_in))
158 if (usin->sin_family != AF_INET)
159 return -EAFNOSUPPORT;
161 nexthop = daddr = usin->sin_addr.s_addr;
162 inet_opt = rcu_dereference_protected(inet->inet_opt,
163 sock_owned_by_user(sk));
164 if (inet_opt && inet_opt->opt.srr) {
167 nexthop = inet_opt->opt.faddr;
170 orig_sport = inet->inet_sport;
171 orig_dport = usin->sin_port;
172 fl4 = &inet->cork.fl.u.ip4;
173 rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
174 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
176 orig_sport, orig_dport, sk, true);
179 if (err == -ENETUNREACH)
180 IP_INC_STATS_BH(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
184 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
189 if (!inet_opt || !inet_opt->opt.srr)
192 if (!inet->inet_saddr)
193 inet->inet_saddr = fl4->saddr;
194 inet->inet_rcv_saddr = inet->inet_saddr;
196 if (tp->rx_opt.ts_recent_stamp && inet->inet_daddr != daddr) {
197 /* Reset inherited state */
198 tp->rx_opt.ts_recent = 0;
199 tp->rx_opt.ts_recent_stamp = 0;
200 if (likely(!tp->repair))
204 if (tcp_death_row.sysctl_tw_recycle &&
205 !tp->rx_opt.ts_recent_stamp && fl4->daddr == daddr)
206 tcp_fetch_timewait_stamp(sk, &rt->dst);
208 inet->inet_dport = usin->sin_port;
209 inet->inet_daddr = daddr;
211 inet_csk(sk)->icsk_ext_hdr_len = 0;
213 inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
215 tp->rx_opt.mss_clamp = TCP_MSS_DEFAULT;
217 /* Socket identity is still unknown (sport may be zero).
218 * However we set state to SYN-SENT and not releasing socket
219 * lock select source port, enter ourselves into the hash tables and
220 * complete initialization after this.
222 tcp_set_state(sk, TCP_SYN_SENT);
223 err = inet_hash_connect(&tcp_death_row, sk);
227 rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
228 inet->inet_sport, inet->inet_dport, sk);
234 /* OK, now commit destination to socket. */
235 sk->sk_gso_type = SKB_GSO_TCPV4;
236 sk_setup_caps(sk, &rt->dst);
238 if (!tp->write_seq && likely(!tp->repair))
239 tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr,
244 inet->inet_id = tp->write_seq ^ jiffies;
246 err = tcp_connect(sk);
256 * This unhashes the socket and releases the local port,
259 tcp_set_state(sk, TCP_CLOSE);
261 sk->sk_route_caps = 0;
262 inet->inet_dport = 0;
265 EXPORT_SYMBOL(tcp_v4_connect);
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.
272 static void tcp_v4_mtu_reduced(struct sock *sk)
274 struct dst_entry *dst;
275 struct inet_sock *inet = inet_sk(sk);
276 u32 mtu = tcp_sk(sk)->mtu_info;
278 dst = inet_csk_update_pmtu(sk, mtu);
282 /* Something is about to be wrong... Remember soft error
283 * for the case, if this connection will not able to recover.
285 if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
286 sk->sk_err_soft = EMSGSIZE;
290 if (inet->pmtudisc != IP_PMTUDISC_DONT &&
291 inet_csk(sk)->icsk_pmtu_cookie > mtu) {
292 tcp_sync_mss(sk, mtu);
294 /* Resend the TCP packet because it's
295 * clear that the old packet has been
296 * dropped. This is the new "fast" path mtu
299 tcp_simple_retransmit(sk);
300 } /* else let the usual retransmit timer handle it */
303 static void do_redirect(struct sk_buff *skb, struct sock *sk)
305 struct dst_entry *dst = __sk_dst_check(sk, 0);
308 dst->ops->redirect(dst, sk, skb);
312 * This routine is called by the ICMP module when it gets some
313 * sort of error condition. If err < 0 then the socket should
314 * be closed and the error returned to the user. If err > 0
315 * it's just the icmp type << 8 | icmp code. After adjustment
316 * header points to the first 8 bytes of the tcp header. We need
317 * to find the appropriate port.
319 * The locking strategy used here is very "optimistic". When
320 * someone else accesses the socket the ICMP is just dropped
321 * and for some paths there is no check at all.
322 * A more general error queue to queue errors for later handling
323 * is probably better.
327 void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
329 const struct iphdr *iph = (const struct iphdr *)icmp_skb->data;
330 struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2));
331 struct inet_connection_sock *icsk;
333 struct inet_sock *inet;
334 const int type = icmp_hdr(icmp_skb)->type;
335 const int code = icmp_hdr(icmp_skb)->code;
338 struct request_sock *req;
342 struct net *net = dev_net(icmp_skb->dev);
344 if (icmp_skb->len < (iph->ihl << 2) + 8) {
345 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
349 sk = inet_lookup(net, &tcp_hashinfo, iph->daddr, th->dest,
350 iph->saddr, th->source, inet_iif(icmp_skb));
352 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
355 if (sk->sk_state == TCP_TIME_WAIT) {
356 inet_twsk_put(inet_twsk(sk));
361 /* If too many ICMPs get dropped on busy
362 * servers this needs to be solved differently.
363 * We do take care of PMTU discovery (RFC1191) special case :
364 * we can receive locally generated ICMP messages while socket is held.
366 if (sock_owned_by_user(sk)) {
367 if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
368 NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
370 if (sk->sk_state == TCP_CLOSE)
373 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
374 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
380 req = tp->fastopen_rsk;
381 seq = ntohl(th->seq);
382 if (sk->sk_state != TCP_LISTEN &&
383 !between(seq, tp->snd_una, tp->snd_nxt) &&
384 (req == NULL || seq != tcp_rsk(req)->snt_isn)) {
385 /* For a Fast Open socket, allow seq to be snt_isn. */
386 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
392 do_redirect(icmp_skb, sk);
394 case ICMP_SOURCE_QUENCH:
395 /* Just silently ignore these. */
397 case ICMP_PARAMETERPROB:
400 case ICMP_DEST_UNREACH:
401 if (code > NR_ICMP_UNREACH)
404 if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
405 /* We are not interested in TCP_LISTEN and open_requests
406 * (SYN-ACKs send out by Linux are always <576bytes so
407 * they should go through unfragmented).
409 if (sk->sk_state == TCP_LISTEN)
413 if (!sock_owned_by_user(sk)) {
414 tcp_v4_mtu_reduced(sk);
416 if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
422 err = icmp_err_convert[code].errno;
423 /* check if icmp_skb allows revert of backoff
424 * (see draft-zimmermann-tcp-lcd) */
425 if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)
427 if (seq != tp->snd_una || !icsk->icsk_retransmits ||
431 /* XXX (TFO) - revisit the following logic for TFO */
433 if (sock_owned_by_user(sk))
436 icsk->icsk_backoff--;
437 inet_csk(sk)->icsk_rto = (tp->srtt ? __tcp_set_rto(tp) :
438 TCP_TIMEOUT_INIT) << icsk->icsk_backoff;
441 skb = tcp_write_queue_head(sk);
444 remaining = icsk->icsk_rto - min(icsk->icsk_rto,
445 tcp_time_stamp - TCP_SKB_CB(skb)->when);
448 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
449 remaining, TCP_RTO_MAX);
451 /* RTO revert clocked out retransmission.
452 * Will retransmit now */
453 tcp_retransmit_timer(sk);
457 case ICMP_TIME_EXCEEDED:
464 /* XXX (TFO) - if it's a TFO socket and has been accepted, rather
465 * than following the TCP_SYN_RECV case and closing the socket,
466 * we ignore the ICMP error and keep trying like a fully established
467 * socket. Is this the right thing to do?
469 if (req && req->sk == NULL)
472 switch (sk->sk_state) {
473 struct request_sock *req, **prev;
475 if (sock_owned_by_user(sk))
478 req = inet_csk_search_req(sk, &prev, th->dest,
479 iph->daddr, iph->saddr);
483 /* ICMPs are not backlogged, hence we cannot get
484 an established socket here.
488 if (seq != tcp_rsk(req)->snt_isn) {
489 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
494 * Still in SYN_RECV, just remove it silently.
495 * There is no good way to pass the error to the newly
496 * created socket, and POSIX does not want network
497 * errors returned from accept().
499 inet_csk_reqsk_queue_drop(sk, req, prev);
500 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
504 case TCP_SYN_RECV: /* Cannot happen.
505 It can f.e. if SYNs crossed,
508 if (!sock_owned_by_user(sk)) {
511 sk->sk_error_report(sk);
515 sk->sk_err_soft = err;
520 /* If we've already connected we will keep trying
521 * until we time out, or the user gives up.
523 * rfc1122 4.2.3.9 allows to consider as hard errors
524 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
525 * but it is obsoleted by pmtu discovery).
527 * Note, that in modern internet, where routing is unreliable
528 * and in each dark corner broken firewalls sit, sending random
529 * errors ordered by their masters even this two messages finally lose
530 * their original sense (even Linux sends invalid PORT_UNREACHs)
532 * Now we are in compliance with RFCs.
537 if (!sock_owned_by_user(sk) && inet->recverr) {
539 sk->sk_error_report(sk);
540 } else { /* Only an error on timeout */
541 sk->sk_err_soft = err;
549 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr)
551 struct tcphdr *th = tcp_hdr(skb);
553 if (skb->ip_summed == CHECKSUM_PARTIAL) {
554 th->check = ~tcp_v4_check(skb->len, saddr, daddr, 0);
555 skb->csum_start = skb_transport_header(skb) - skb->head;
556 skb->csum_offset = offsetof(struct tcphdr, check);
558 th->check = tcp_v4_check(skb->len, saddr, daddr,
565 /* This routine computes an IPv4 TCP checksum. */
566 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)
568 const struct inet_sock *inet = inet_sk(sk);
570 __tcp_v4_send_check(skb, inet->inet_saddr, inet->inet_daddr);
572 EXPORT_SYMBOL(tcp_v4_send_check);
575 * This routine will send an RST to the other tcp.
577 * Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
579 * Answer: if a packet caused RST, it is not for a socket
580 * existing in our system, if it is matched to a socket,
581 * it is just duplicate segment or bug in other side's TCP.
582 * So that we build reply only basing on parameters
583 * arrived with segment.
584 * Exception: precedence violation. We do not implement it in any case.
587 static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
589 const struct tcphdr *th = tcp_hdr(skb);
592 #ifdef CONFIG_TCP_MD5SIG
593 __be32 opt[(TCPOLEN_MD5SIG_ALIGNED >> 2)];
596 struct ip_reply_arg arg;
597 #ifdef CONFIG_TCP_MD5SIG
598 struct tcp_md5sig_key *key;
599 const __u8 *hash_location = NULL;
600 unsigned char newhash[16];
602 struct sock *sk1 = NULL;
606 /* Never send a reset in response to a reset. */
610 if (skb_rtable(skb)->rt_type != RTN_LOCAL)
613 /* Swap the send and the receive. */
614 memset(&rep, 0, sizeof(rep));
615 rep.th.dest = th->source;
616 rep.th.source = th->dest;
617 rep.th.doff = sizeof(struct tcphdr) / 4;
621 rep.th.seq = th->ack_seq;
624 rep.th.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
625 skb->len - (th->doff << 2));
628 memset(&arg, 0, sizeof(arg));
629 arg.iov[0].iov_base = (unsigned char *)&rep;
630 arg.iov[0].iov_len = sizeof(rep.th);
632 #ifdef CONFIG_TCP_MD5SIG
633 hash_location = tcp_parse_md5sig_option(th);
634 if (!sk && hash_location) {
636 * active side is lost. Try to find listening socket through
637 * source port, and then find md5 key through listening socket.
638 * we are not loose security here:
639 * Incoming packet is checked with md5 hash with finding key,
640 * no RST generated if md5 hash doesn't match.
642 sk1 = __inet_lookup_listener(dev_net(skb_dst(skb)->dev),
643 &tcp_hashinfo, ip_hdr(skb)->saddr,
644 th->source, ip_hdr(skb)->daddr,
645 ntohs(th->source), inet_iif(skb));
646 /* don't send rst if it can't find key */
650 key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
651 &ip_hdr(skb)->saddr, AF_INET);
655 genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, NULL, skb);
656 if (genhash || memcmp(hash_location, newhash, 16) != 0)
659 key = sk ? tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
665 rep.opt[0] = htonl((TCPOPT_NOP << 24) |
667 (TCPOPT_MD5SIG << 8) |
669 /* Update length and the length the header thinks exists */
670 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
671 rep.th.doff = arg.iov[0].iov_len / 4;
673 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
674 key, ip_hdr(skb)->saddr,
675 ip_hdr(skb)->daddr, &rep.th);
678 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
679 ip_hdr(skb)->saddr, /* XXX */
680 arg.iov[0].iov_len, IPPROTO_TCP, 0);
681 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
682 arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
683 /* When socket is gone, all binding information is lost.
684 * routing might fail in this case. No choice here, if we choose to force
685 * input interface, we will misroute in case of asymmetric route.
688 arg.bound_dev_if = sk->sk_bound_dev_if;
690 net = dev_net(skb_dst(skb)->dev);
691 arg.tos = ip_hdr(skb)->tos;
692 ip_send_unicast_reply(net, skb, ip_hdr(skb)->saddr,
693 ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len);
695 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
696 TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
698 #ifdef CONFIG_TCP_MD5SIG
707 /* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
708 outside socket context is ugly, certainly. What can I do?
711 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
712 u32 win, u32 tsval, u32 tsecr, int oif,
713 struct tcp_md5sig_key *key,
714 int reply_flags, u8 tos)
716 const struct tcphdr *th = tcp_hdr(skb);
719 __be32 opt[(TCPOLEN_TSTAMP_ALIGNED >> 2)
720 #ifdef CONFIG_TCP_MD5SIG
721 + (TCPOLEN_MD5SIG_ALIGNED >> 2)
725 struct ip_reply_arg arg;
726 struct net *net = dev_net(skb_dst(skb)->dev);
728 memset(&rep.th, 0, sizeof(struct tcphdr));
729 memset(&arg, 0, sizeof(arg));
731 arg.iov[0].iov_base = (unsigned char *)&rep;
732 arg.iov[0].iov_len = sizeof(rep.th);
734 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
735 (TCPOPT_TIMESTAMP << 8) |
737 rep.opt[1] = htonl(tsval);
738 rep.opt[2] = htonl(tsecr);
739 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
742 /* Swap the send and the receive. */
743 rep.th.dest = th->source;
744 rep.th.source = th->dest;
745 rep.th.doff = arg.iov[0].iov_len / 4;
746 rep.th.seq = htonl(seq);
747 rep.th.ack_seq = htonl(ack);
749 rep.th.window = htons(win);
751 #ifdef CONFIG_TCP_MD5SIG
753 int offset = (tsecr) ? 3 : 0;
755 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
757 (TCPOPT_MD5SIG << 8) |
759 arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
760 rep.th.doff = arg.iov[0].iov_len/4;
762 tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
763 key, ip_hdr(skb)->saddr,
764 ip_hdr(skb)->daddr, &rep.th);
767 arg.flags = reply_flags;
768 arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
769 ip_hdr(skb)->saddr, /* XXX */
770 arg.iov[0].iov_len, IPPROTO_TCP, 0);
771 arg.csumoffset = offsetof(struct tcphdr, check) / 2;
773 arg.bound_dev_if = oif;
775 ip_send_unicast_reply(net, skb, ip_hdr(skb)->saddr,
776 ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len);
778 TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
781 static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
783 struct inet_timewait_sock *tw = inet_twsk(sk);
784 struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
786 tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
787 tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
788 tcp_time_stamp + tcptw->tw_ts_offset,
791 tcp_twsk_md5_key(tcptw),
792 tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
799 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
800 struct request_sock *req)
802 /* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
803 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
805 tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
806 tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
807 tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
811 tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
813 inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
818 * Send a SYN-ACK after having received a SYN.
819 * This still operates on a request_sock only, not on a big
822 static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
823 struct request_sock *req,
827 const struct inet_request_sock *ireq = inet_rsk(req);
830 struct sk_buff * skb;
832 /* First, grab a route. */
833 if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
836 skb = tcp_make_synack(sk, dst, req, NULL);
839 __tcp_v4_send_check(skb, ireq->loc_addr, ireq->rmt_addr);
841 skb_set_queue_mapping(skb, queue_mapping);
842 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
845 err = net_xmit_eval(err);
846 if (!tcp_rsk(req)->snt_synack && !err)
847 tcp_rsk(req)->snt_synack = tcp_time_stamp;
853 static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req)
855 int res = tcp_v4_send_synack(sk, NULL, req, 0, false);
858 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
863 * IPv4 request_sock destructor.
865 static void tcp_v4_reqsk_destructor(struct request_sock *req)
867 kfree(inet_rsk(req)->opt);
871 * Return true if a syncookie should be sent
873 bool tcp_syn_flood_action(struct sock *sk,
874 const struct sk_buff *skb,
877 const char *msg = "Dropping request";
878 bool want_cookie = false;
879 struct listen_sock *lopt;
883 #ifdef CONFIG_SYN_COOKIES
884 if (sysctl_tcp_syncookies) {
885 msg = "Sending cookies";
887 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDOCOOKIES);
890 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
892 lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
893 if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {
894 lopt->synflood_warned = 1;
895 pr_info("%s: Possible SYN flooding on port %d. %s. Check SNMP counters.\n",
896 proto, ntohs(tcp_hdr(skb)->dest), msg);
900 EXPORT_SYMBOL(tcp_syn_flood_action);
903 * Save and compile IPv4 options into the request_sock if needed.
905 static struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
907 const struct ip_options *opt = &(IPCB(skb)->opt);
908 struct ip_options_rcu *dopt = NULL;
910 if (opt && opt->optlen) {
911 int opt_size = sizeof(*dopt) + opt->optlen;
913 dopt = kmalloc(opt_size, GFP_ATOMIC);
915 if (ip_options_echo(&dopt->opt, skb)) {
924 #ifdef CONFIG_TCP_MD5SIG
926 * RFC2385 MD5 checksumming requires a mapping of
927 * IP address->MD5 Key.
928 * We need to maintain these in the sk structure.
931 /* Find the Key structure for an address. */
932 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
933 const union tcp_md5_addr *addr,
936 struct tcp_sock *tp = tcp_sk(sk);
937 struct tcp_md5sig_key *key;
938 unsigned int size = sizeof(struct in_addr);
939 struct tcp_md5sig_info *md5sig;
941 /* caller either holds rcu_read_lock() or socket lock */
942 md5sig = rcu_dereference_check(tp->md5sig_info,
943 sock_owned_by_user(sk) ||
944 lockdep_is_held(&sk->sk_lock.slock));
947 #if IS_ENABLED(CONFIG_IPV6)
948 if (family == AF_INET6)
949 size = sizeof(struct in6_addr);
951 hlist_for_each_entry_rcu(key, &md5sig->head, node) {
952 if (key->family != family)
954 if (!memcmp(&key->addr, addr, size))
959 EXPORT_SYMBOL(tcp_md5_do_lookup);
961 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
962 struct sock *addr_sk)
964 union tcp_md5_addr *addr;
966 addr = (union tcp_md5_addr *)&inet_sk(addr_sk)->inet_daddr;
967 return tcp_md5_do_lookup(sk, addr, AF_INET);
969 EXPORT_SYMBOL(tcp_v4_md5_lookup);
971 static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
972 struct request_sock *req)
974 union tcp_md5_addr *addr;
976 addr = (union tcp_md5_addr *)&inet_rsk(req)->rmt_addr;
977 return tcp_md5_do_lookup(sk, addr, AF_INET);
980 /* This can be called on a newly created socket, from other files */
981 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
982 int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
984 /* Add Key to the list */
985 struct tcp_md5sig_key *key;
986 struct tcp_sock *tp = tcp_sk(sk);
987 struct tcp_md5sig_info *md5sig;
989 key = tcp_md5_do_lookup(sk, addr, family);
991 /* Pre-existing entry - just update that one. */
992 memcpy(key->key, newkey, newkeylen);
993 key->keylen = newkeylen;
997 md5sig = rcu_dereference_protected(tp->md5sig_info,
998 sock_owned_by_user(sk));
1000 md5sig = kmalloc(sizeof(*md5sig), gfp);
1004 sk_nocaps_add(sk, NETIF_F_GSO_MASK);
1005 INIT_HLIST_HEAD(&md5sig->head);
1006 rcu_assign_pointer(tp->md5sig_info, md5sig);
1009 key = sock_kmalloc(sk, sizeof(*key), gfp);
1012 if (!tcp_alloc_md5sig_pool()) {
1013 sock_kfree_s(sk, key, sizeof(*key));
1017 memcpy(key->key, newkey, newkeylen);
1018 key->keylen = newkeylen;
1019 key->family = family;
1020 memcpy(&key->addr, addr,
1021 (family == AF_INET6) ? sizeof(struct in6_addr) :
1022 sizeof(struct in_addr));
1023 hlist_add_head_rcu(&key->node, &md5sig->head);
1026 EXPORT_SYMBOL(tcp_md5_do_add);
1028 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
1030 struct tcp_md5sig_key *key;
1032 key = tcp_md5_do_lookup(sk, addr, family);
1035 hlist_del_rcu(&key->node);
1036 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
1037 kfree_rcu(key, rcu);
1040 EXPORT_SYMBOL(tcp_md5_do_del);
1042 static void tcp_clear_md5_list(struct sock *sk)
1044 struct tcp_sock *tp = tcp_sk(sk);
1045 struct tcp_md5sig_key *key;
1046 struct hlist_node *n;
1047 struct tcp_md5sig_info *md5sig;
1049 md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
1051 hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
1052 hlist_del_rcu(&key->node);
1053 atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
1054 kfree_rcu(key, rcu);
1058 static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
1061 struct tcp_md5sig cmd;
1062 struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
1064 if (optlen < sizeof(cmd))
1067 if (copy_from_user(&cmd, optval, sizeof(cmd)))
1070 if (sin->sin_family != AF_INET)
1073 if (!cmd.tcpm_key || !cmd.tcpm_keylen)
1074 return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1077 if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
1080 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
1081 AF_INET, cmd.tcpm_key, cmd.tcpm_keylen,
1085 static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
1086 __be32 daddr, __be32 saddr, int nbytes)
1088 struct tcp4_pseudohdr *bp;
1089 struct scatterlist sg;
1091 bp = &hp->md5_blk.ip4;
1094 * 1. the TCP pseudo-header (in the order: source IP address,
1095 * destination IP address, zero-padded protocol number, and
1101 bp->protocol = IPPROTO_TCP;
1102 bp->len = cpu_to_be16(nbytes);
1104 sg_init_one(&sg, bp, sizeof(*bp));
1105 return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
1108 static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
1109 __be32 daddr, __be32 saddr, const struct tcphdr *th)
1111 struct tcp_md5sig_pool *hp;
1112 struct hash_desc *desc;
1114 hp = tcp_get_md5sig_pool();
1116 goto clear_hash_noput;
1117 desc = &hp->md5_desc;
1119 if (crypto_hash_init(desc))
1121 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
1123 if (tcp_md5_hash_header(hp, th))
1125 if (tcp_md5_hash_key(hp, key))
1127 if (crypto_hash_final(desc, md5_hash))
1130 tcp_put_md5sig_pool();
1134 tcp_put_md5sig_pool();
1136 memset(md5_hash, 0, 16);
1140 int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1141 const struct sock *sk, const struct request_sock *req,
1142 const struct sk_buff *skb)
1144 struct tcp_md5sig_pool *hp;
1145 struct hash_desc *desc;
1146 const struct tcphdr *th = tcp_hdr(skb);
1147 __be32 saddr, daddr;
1150 saddr = inet_sk(sk)->inet_saddr;
1151 daddr = inet_sk(sk)->inet_daddr;
1153 saddr = inet_rsk(req)->loc_addr;
1154 daddr = inet_rsk(req)->rmt_addr;
1156 const struct iphdr *iph = ip_hdr(skb);
1161 hp = tcp_get_md5sig_pool();
1163 goto clear_hash_noput;
1164 desc = &hp->md5_desc;
1166 if (crypto_hash_init(desc))
1169 if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
1171 if (tcp_md5_hash_header(hp, th))
1173 if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
1175 if (tcp_md5_hash_key(hp, key))
1177 if (crypto_hash_final(desc, md5_hash))
1180 tcp_put_md5sig_pool();
1184 tcp_put_md5sig_pool();
1186 memset(md5_hash, 0, 16);
1189 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
1191 static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
1194 * This gets called for each TCP segment that arrives
1195 * so we want to be efficient.
1196 * We have 3 drop cases:
1197 * o No MD5 hash and one expected.
1198 * o MD5 hash and we're not expecting one.
1199 * o MD5 hash and its wrong.
1201 const __u8 *hash_location = NULL;
1202 struct tcp_md5sig_key *hash_expected;
1203 const struct iphdr *iph = ip_hdr(skb);
1204 const struct tcphdr *th = tcp_hdr(skb);
1206 unsigned char newhash[16];
1208 hash_expected = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&iph->saddr,
1210 hash_location = tcp_parse_md5sig_option(th);
1212 /* We've parsed the options - do we have a hash? */
1213 if (!hash_expected && !hash_location)
1216 if (hash_expected && !hash_location) {
1217 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
1221 if (!hash_expected && hash_location) {
1222 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
1226 /* Okay, so this is hash_expected and hash_location -
1227 * so we need to calculate the checksum.
1229 genhash = tcp_v4_md5_hash_skb(newhash,
1233 if (genhash || memcmp(hash_location, newhash, 16) != 0) {
1234 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
1235 &iph->saddr, ntohs(th->source),
1236 &iph->daddr, ntohs(th->dest),
1237 genhash ? " tcp_v4_calc_md5_hash failed"
1246 struct request_sock_ops tcp_request_sock_ops __read_mostly = {
1248 .obj_size = sizeof(struct tcp_request_sock),
1249 .rtx_syn_ack = tcp_v4_rtx_synack,
1250 .send_ack = tcp_v4_reqsk_send_ack,
1251 .destructor = tcp_v4_reqsk_destructor,
1252 .send_reset = tcp_v4_send_reset,
1253 .syn_ack_timeout = tcp_syn_ack_timeout,
1256 #ifdef CONFIG_TCP_MD5SIG
1257 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
1258 .md5_lookup = tcp_v4_reqsk_md5_lookup,
1259 .calc_md5_hash = tcp_v4_md5_hash_skb,
1263 static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
1264 struct request_sock *req,
1265 struct tcp_fastopen_cookie *foc,
1266 struct tcp_fastopen_cookie *valid_foc)
1268 bool skip_cookie = false;
1269 struct fastopen_queue *fastopenq;
1271 if (likely(!fastopen_cookie_present(foc))) {
1272 /* See include/net/tcp.h for the meaning of these knobs */
1273 if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
1274 ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
1275 (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
1276 skip_cookie = true; /* no cookie to validate */
1280 fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
1281 /* A FO option is present; bump the counter. */
1282 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
1284 /* Make sure the listener has enabled fastopen, and we don't
1285 * exceed the max # of pending TFO requests allowed before trying
1286 * to validating the cookie in order to avoid burning CPU cycles
1289 * XXX (TFO) - The implication of checking the max_qlen before
1290 * processing a cookie request is that clients can't differentiate
1291 * between qlen overflow causing Fast Open to be disabled
1292 * temporarily vs a server not supporting Fast Open at all.
1294 if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
1295 fastopenq == NULL || fastopenq->max_qlen == 0)
1298 if (fastopenq->qlen >= fastopenq->max_qlen) {
1299 struct request_sock *req1;
1300 spin_lock(&fastopenq->lock);
1301 req1 = fastopenq->rskq_rst_head;
1302 if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
1303 spin_unlock(&fastopenq->lock);
1304 NET_INC_STATS_BH(sock_net(sk),
1305 LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
1306 /* Avoid bumping LINUX_MIB_TCPFASTOPENPASSIVEFAIL*/
1310 fastopenq->rskq_rst_head = req1->dl_next;
1312 spin_unlock(&fastopenq->lock);
1316 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1319 if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
1320 if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
1321 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
1322 if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
1323 memcmp(&foc->val[0], &valid_foc->val[0],
1324 TCP_FASTOPEN_COOKIE_SIZE) != 0)
1326 valid_foc->len = -1;
1328 /* Acknowledge the data received from the peer. */
1329 tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1331 } else if (foc->len == 0) { /* Client requesting a cookie */
1332 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
1333 NET_INC_STATS_BH(sock_net(sk),
1334 LINUX_MIB_TCPFASTOPENCOOKIEREQD);
1336 /* Client sent a cookie with wrong size. Treat it
1337 * the same as invalid and return a valid one.
1339 tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
1344 static int tcp_v4_conn_req_fastopen(struct sock *sk,
1345 struct sk_buff *skb,
1346 struct sk_buff *skb_synack,
1347 struct request_sock *req)
1349 struct tcp_sock *tp = tcp_sk(sk);
1350 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1351 const struct inet_request_sock *ireq = inet_rsk(req);
1355 req->num_retrans = 0;
1356 req->num_timeout = 0;
1359 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
1360 if (child == NULL) {
1361 NET_INC_STATS_BH(sock_net(sk),
1362 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
1363 kfree_skb(skb_synack);
1366 err = ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr,
1367 ireq->rmt_addr, ireq->opt);
1368 err = net_xmit_eval(err);
1370 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1371 /* XXX (TFO) - is it ok to ignore error and continue? */
1373 spin_lock(&queue->fastopenq->lock);
1374 queue->fastopenq->qlen++;
1375 spin_unlock(&queue->fastopenq->lock);
1377 /* Initialize the child socket. Have to fix some values to take
1378 * into account the child is a Fast Open socket and is created
1379 * only out of the bits carried in the SYN packet.
1383 tp->fastopen_rsk = req;
1384 /* Do a hold on the listner sk so that if the listener is being
1385 * closed, the child that has been accepted can live on and still
1386 * access listen_lock.
1389 tcp_rsk(req)->listener = sk;
1391 /* RFC1323: The window in SYN & SYN/ACK segments is never
1392 * scaled. So correct it appropriately.
1394 tp->snd_wnd = ntohs(tcp_hdr(skb)->window);
1396 /* Activate the retrans timer so that SYNACK can be retransmitted.
1397 * The request socket is not added to the SYN table of the parent
1398 * because it's been added to the accept queue directly.
1400 inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
1401 TCP_TIMEOUT_INIT, TCP_RTO_MAX);
1403 /* Add the child socket directly into the accept queue */
1404 inet_csk_reqsk_queue_add(sk, req, child);
1406 /* Now finish processing the fastopen child socket. */
1407 inet_csk(child)->icsk_af_ops->rebuild_header(child);
1408 tcp_init_congestion_control(child);
1409 tcp_mtup_init(child);
1410 tcp_init_buffer_space(child);
1411 tcp_init_metrics(child);
1413 /* Queue the data carried in the SYN packet. We need to first
1414 * bump skb's refcnt because the caller will attempt to free it.
1416 * XXX (TFO) - we honor a zero-payload TFO request for now.
1417 * (Any reason not to?)
1419 if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
1420 /* Don't queue the skb if there is no payload in SYN.
1421 * XXX (TFO) - How about SYN+FIN?
1423 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1427 __skb_pull(skb, tcp_hdr(skb)->doff * 4);
1428 skb_set_owner_r(skb, child);
1429 __skb_queue_tail(&child->sk_receive_queue, skb);
1430 tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
1431 tp->syn_data_acked = 1;
1433 sk->sk_data_ready(sk, 0);
1434 bh_unlock_sock(child);
1436 WARN_ON(req->sk == NULL);
1440 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
1442 struct tcp_options_received tmp_opt;
1443 struct request_sock *req;
1444 struct inet_request_sock *ireq;
1445 struct tcp_sock *tp = tcp_sk(sk);
1446 struct dst_entry *dst = NULL;
1447 __be32 saddr = ip_hdr(skb)->saddr;
1448 __be32 daddr = ip_hdr(skb)->daddr;
1449 __u32 isn = TCP_SKB_CB(skb)->when;
1450 bool want_cookie = false;
1452 struct tcp_fastopen_cookie foc = { .len = -1 };
1453 struct tcp_fastopen_cookie valid_foc = { .len = -1 };
1454 struct sk_buff *skb_synack;
1457 /* Never answer to SYNs send to broadcast or multicast */
1458 if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
1461 /* TW buckets are converted to open requests without
1462 * limitations, they conserve resources and peer is
1463 * evidently real one.
1465 if ((sysctl_tcp_syncookies == 2 ||
1466 inet_csk_reqsk_queue_is_full(sk)) && !isn) {
1467 want_cookie = tcp_syn_flood_action(sk, skb, "TCP");
1472 /* Accept backlog is full. If we have already queued enough
1473 * of warm entries in syn queue, drop request. It is better than
1474 * clogging syn queue with openreqs with exponentially increasing
1477 if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
1478 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1482 req = inet_reqsk_alloc(&tcp_request_sock_ops);
1486 #ifdef CONFIG_TCP_MD5SIG
1487 tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
1490 tcp_clear_options(&tmp_opt);
1491 tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
1492 tmp_opt.user_mss = tp->rx_opt.user_mss;
1493 tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
1495 if (want_cookie && !tmp_opt.saw_tstamp)
1496 tcp_clear_options(&tmp_opt);
1498 tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
1499 tcp_openreq_init(req, &tmp_opt, skb);
1501 ireq = inet_rsk(req);
1502 ireq->loc_addr = daddr;
1503 ireq->rmt_addr = saddr;
1504 ireq->no_srccheck = inet_sk(sk)->transparent;
1505 ireq->opt = tcp_v4_save_options(skb);
1507 if (security_inet_conn_request(sk, skb, req))
1510 if (!want_cookie || tmp_opt.tstamp_ok)
1511 TCP_ECN_create_request(req, skb, sock_net(sk));
1514 isn = cookie_v4_init_sequence(sk, skb, &req->mss);
1515 req->cookie_ts = tmp_opt.tstamp_ok;
1517 /* VJ's idea. We save last timestamp seen
1518 * from the destination in peer table, when entering
1519 * state TIME-WAIT, and check against it before
1520 * accepting new connection request.
1522 * If "isn" is not zero, this request hit alive
1523 * timewait bucket, so that all the necessary checks
1524 * are made in the function processing timewait state.
1526 if (tmp_opt.saw_tstamp &&
1527 tcp_death_row.sysctl_tw_recycle &&
1528 (dst = inet_csk_route_req(sk, &fl4, req)) != NULL &&
1529 fl4.daddr == saddr) {
1530 if (!tcp_peer_is_proven(req, dst, true)) {
1531 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
1532 goto drop_and_release;
1535 /* Kill the following clause, if you dislike this way. */
1536 else if (!sysctl_tcp_syncookies &&
1537 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
1538 (sysctl_max_syn_backlog >> 2)) &&
1539 !tcp_peer_is_proven(req, dst, false)) {
1540 /* Without syncookies last quarter of
1541 * backlog is filled with destinations,
1542 * proven to be alive.
1543 * It means that we continue to communicate
1544 * to destinations, already remembered
1545 * to the moment of synflood.
1547 LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
1548 &saddr, ntohs(tcp_hdr(skb)->source));
1549 goto drop_and_release;
1552 isn = tcp_v4_init_sequence(skb);
1554 tcp_rsk(req)->snt_isn = isn;
1557 dst = inet_csk_route_req(sk, &fl4, req);
1561 do_fastopen = tcp_fastopen_check(sk, skb, req, &foc, &valid_foc);
1563 /* We don't call tcp_v4_send_synack() directly because we need
1564 * to make sure a child socket can be created successfully before
1565 * sending back synack!
1567 * XXX (TFO) - Ideally one would simply call tcp_v4_send_synack()
1568 * (or better yet, call tcp_send_synack() in the child context
1569 * directly, but will have to fix bunch of other code first)
1570 * after syn_recv_sock() except one will need to first fix the
1571 * latter to remove its dependency on the current implementation
1572 * of tcp_v4_send_synack()->tcp_select_initial_window().
1574 skb_synack = tcp_make_synack(sk, dst, req,
1575 fastopen_cookie_present(&valid_foc) ? &valid_foc : NULL);
1578 __tcp_v4_send_check(skb_synack, ireq->loc_addr, ireq->rmt_addr);
1579 skb_set_queue_mapping(skb_synack, skb_get_queue_mapping(skb));
1583 if (likely(!do_fastopen)) {
1585 err = ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr,
1586 ireq->rmt_addr, ireq->opt);
1587 err = net_xmit_eval(err);
1588 if (err || want_cookie)
1591 tcp_rsk(req)->snt_synack = tcp_time_stamp;
1592 tcp_rsk(req)->listener = NULL;
1593 /* Add the request_sock to the SYN table */
1594 inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
1595 if (fastopen_cookie_present(&foc) && foc.len != 0)
1596 NET_INC_STATS_BH(sock_net(sk),
1597 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
1598 } else if (tcp_v4_conn_req_fastopen(sk, skb, skb_synack, req))
1608 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1611 EXPORT_SYMBOL(tcp_v4_conn_request);
1615 * The three way handshake has completed - we got a valid synack -
1616 * now create the new socket.
1618 struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
1619 struct request_sock *req,
1620 struct dst_entry *dst)
1622 struct inet_request_sock *ireq;
1623 struct inet_sock *newinet;
1624 struct tcp_sock *newtp;
1626 #ifdef CONFIG_TCP_MD5SIG
1627 struct tcp_md5sig_key *key;
1629 struct ip_options_rcu *inet_opt;
1631 if (sk_acceptq_is_full(sk))
1634 newsk = tcp_create_openreq_child(sk, req, skb);
1638 newsk->sk_gso_type = SKB_GSO_TCPV4;
1639 inet_sk_rx_dst_set(newsk, skb);
1641 newtp = tcp_sk(newsk);
1642 newinet = inet_sk(newsk);
1643 ireq = inet_rsk(req);
1644 newinet->inet_daddr = ireq->rmt_addr;
1645 newinet->inet_rcv_saddr = ireq->loc_addr;
1646 newinet->inet_saddr = ireq->loc_addr;
1647 inet_opt = ireq->opt;
1648 rcu_assign_pointer(newinet->inet_opt, inet_opt);
1650 newinet->mc_index = inet_iif(skb);
1651 newinet->mc_ttl = ip_hdr(skb)->ttl;
1652 newinet->rcv_tos = ip_hdr(skb)->tos;
1653 inet_csk(newsk)->icsk_ext_hdr_len = 0;
1655 inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
1656 newinet->inet_id = newtp->write_seq ^ jiffies;
1659 dst = inet_csk_route_child_sock(sk, newsk, req);
1663 /* syncookie case : see end of cookie_v4_check() */
1665 sk_setup_caps(newsk, dst);
1667 tcp_mtup_init(newsk);
1668 tcp_sync_mss(newsk, dst_mtu(dst));
1669 newtp->advmss = dst_metric_advmss(dst);
1670 if (tcp_sk(sk)->rx_opt.user_mss &&
1671 tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
1672 newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
1674 tcp_initialize_rcv_mss(newsk);
1676 #ifdef CONFIG_TCP_MD5SIG
1677 /* Copy over the MD5 key from the original socket */
1678 key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&newinet->inet_daddr,
1682 * We're using one, so create a matching key
1683 * on the newsk structure. If we fail to get
1684 * memory, then we end up not copying the key
1687 tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newinet->inet_daddr,
1688 AF_INET, key->key, key->keylen, GFP_ATOMIC);
1689 sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
1693 if (__inet_inherit_port(sk, newsk) < 0)
1695 __inet_hash_nolisten(newsk, NULL);
1700 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
1704 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
1707 inet_csk_prepare_forced_close(newsk);
1711 EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
1713 static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
1715 struct tcphdr *th = tcp_hdr(skb);
1716 const struct iphdr *iph = ip_hdr(skb);
1718 struct request_sock **prev;
1719 /* Find possible connection requests. */
1720 struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
1721 iph->saddr, iph->daddr);
1723 return tcp_check_req(sk, skb, req, prev, false);
1725 nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
1726 th->source, iph->daddr, th->dest, inet_iif(skb));
1729 if (nsk->sk_state != TCP_TIME_WAIT) {
1733 inet_twsk_put(inet_twsk(nsk));
1737 #ifdef CONFIG_SYN_COOKIES
1739 sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
1744 static __sum16 tcp_v4_checksum_init(struct sk_buff *skb)
1746 const struct iphdr *iph = ip_hdr(skb);
1748 if (skb->ip_summed == CHECKSUM_COMPLETE) {
1749 if (!tcp_v4_check(skb->len, iph->saddr,
1750 iph->daddr, skb->csum)) {
1751 skb->ip_summed = CHECKSUM_UNNECESSARY;
1756 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
1757 skb->len, IPPROTO_TCP, 0);
1759 if (skb->len <= 76) {
1760 return __skb_checksum_complete(skb);
1766 /* The socket must have it's spinlock held when we get
1769 * We have a potential double-lock case here, so even when
1770 * doing backlog processing we use the BH locking scheme.
1771 * This is because we cannot sleep with the original spinlock
1774 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
1777 #ifdef CONFIG_TCP_MD5SIG
1779 * We really want to reject the packet as early as possible
1781 * o We're expecting an MD5'd packet and this is no MD5 tcp option
1782 * o There is an MD5 option and we're not expecting one
1784 if (tcp_v4_inbound_md5_hash(sk, skb))
1788 if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
1789 struct dst_entry *dst = sk->sk_rx_dst;
1791 sock_rps_save_rxhash(sk, skb);
1793 if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
1794 dst->ops->check(dst, 0) == NULL) {
1796 sk->sk_rx_dst = NULL;
1799 if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
1806 if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
1809 if (sk->sk_state == TCP_LISTEN) {
1810 struct sock *nsk = tcp_v4_hnd_req(sk, skb);
1815 sock_rps_save_rxhash(nsk, skb);
1816 if (tcp_child_process(sk, nsk, skb)) {
1823 sock_rps_save_rxhash(sk, skb);
1825 if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) {
1832 tcp_v4_send_reset(rsk, skb);
1835 /* Be careful here. If this function gets more complicated and
1836 * gcc suffers from register pressure on the x86, sk (in %ebx)
1837 * might be destroyed here. This current version compiles correctly,
1838 * but you have been warned.
1843 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
1844 TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
1847 EXPORT_SYMBOL(tcp_v4_do_rcv);
1849 void tcp_v4_early_demux(struct sk_buff *skb)
1851 const struct iphdr *iph;
1852 const struct tcphdr *th;
1855 if (skb->pkt_type != PACKET_HOST)
1858 if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
1864 if (th->doff < sizeof(struct tcphdr) / 4)
1867 sk = __inet_lookup_established(dev_net(skb->dev), &tcp_hashinfo,
1868 iph->saddr, th->source,
1869 iph->daddr, ntohs(th->dest),
1873 skb->destructor = sock_edemux;
1874 if (sk->sk_state != TCP_TIME_WAIT) {
1875 struct dst_entry *dst = sk->sk_rx_dst;
1878 dst = dst_check(dst, 0);
1880 inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
1881 skb_dst_set_noref(skb, dst);
1886 /* Packet is added to VJ-style prequeue for processing in process
1887 * context, if a reader task is waiting. Apparently, this exciting
1888 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1889 * failed somewhere. Latency? Burstiness? Well, at least now we will
1890 * see, why it failed. 8)8) --ANK
1893 bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1895 struct tcp_sock *tp = tcp_sk(sk);
1897 if (sysctl_tcp_low_latency || !tp->ucopy.task)
1900 if (skb->len <= tcp_hdrlen(skb) &&
1901 skb_queue_len(&tp->ucopy.prequeue) == 0)
1905 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1906 tp->ucopy.memory += skb->truesize;
1907 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1908 struct sk_buff *skb1;
1910 BUG_ON(sock_owned_by_user(sk));
1912 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1913 sk_backlog_rcv(sk, skb1);
1914 NET_INC_STATS_BH(sock_net(sk),
1915 LINUX_MIB_TCPPREQUEUEDROPPED);
1918 tp->ucopy.memory = 0;
1919 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1920 wake_up_interruptible_sync_poll(sk_sleep(sk),
1921 POLLIN | POLLRDNORM | POLLRDBAND);
1922 if (!inet_csk_ack_scheduled(sk))
1923 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1924 (3 * tcp_rto_min(sk)) / 4,
1929 EXPORT_SYMBOL(tcp_prequeue);
1935 int tcp_v4_rcv(struct sk_buff *skb)
1937 const struct iphdr *iph;
1938 const struct tcphdr *th;
1941 struct net *net = dev_net(skb->dev);
1943 if (skb->pkt_type != PACKET_HOST)
1946 /* Count it even if it's bad */
1947 TCP_INC_STATS_BH(net, TCP_MIB_INSEGS);
1949 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
1954 if (th->doff < sizeof(struct tcphdr) / 4)
1956 if (!pskb_may_pull(skb, th->doff * 4))
1959 /* An explanation is required here, I think.
1960 * Packet length and doff are validated by header prediction,
1961 * provided case of th->doff==0 is eliminated.
1962 * So, we defer the checks. */
1963 if (!skb_csum_unnecessary(skb) && tcp_v4_checksum_init(skb))
1968 TCP_SKB_CB(skb)->seq = ntohl(th->seq);
1969 TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
1970 skb->len - th->doff * 4);
1971 TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
1972 TCP_SKB_CB(skb)->when = 0;
1973 TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
1974 TCP_SKB_CB(skb)->sacked = 0;
1976 sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
1981 if (sk->sk_state == TCP_TIME_WAIT)
1984 if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
1985 NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
1986 goto discard_and_relse;
1989 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
1990 goto discard_and_relse;
1993 if (sk_filter(sk, skb))
1994 goto discard_and_relse;
1996 sk_mark_napi_id(sk, skb);
1999 bh_lock_sock_nested(sk);
2001 if (!sock_owned_by_user(sk)) {
2002 #ifdef CONFIG_NET_DMA
2003 struct tcp_sock *tp = tcp_sk(sk);
2004 if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
2005 tp->ucopy.dma_chan = net_dma_find_channel();
2006 if (tp->ucopy.dma_chan)
2007 ret = tcp_v4_do_rcv(sk, skb);
2011 if (!tcp_prequeue(sk, skb))
2012 ret = tcp_v4_do_rcv(sk, skb);
2014 } else if (unlikely(sk_add_backlog(sk, skb,
2015 sk->sk_rcvbuf + sk->sk_sndbuf))) {
2017 NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
2018 goto discard_and_relse;
2027 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
2030 if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
2032 TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
2034 TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
2036 tcp_v4_send_reset(NULL, skb);
2040 /* Discard frame. */
2049 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
2050 inet_twsk_put(inet_twsk(sk));
2054 if (skb->len < (th->doff << 2)) {
2055 inet_twsk_put(inet_twsk(sk));
2058 if (tcp_checksum_complete(skb)) {
2059 inet_twsk_put(inet_twsk(sk));
2062 switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
2064 struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
2066 iph->saddr, th->source,
2067 iph->daddr, th->dest,
2070 inet_twsk_deschedule(inet_twsk(sk), &tcp_death_row);
2071 inet_twsk_put(inet_twsk(sk));
2075 /* Fall through to ACK */
2078 tcp_v4_timewait_ack(sk, skb);
2082 case TCP_TW_SUCCESS:;
2087 static struct timewait_sock_ops tcp_timewait_sock_ops = {
2088 .twsk_obj_size = sizeof(struct tcp_timewait_sock),
2089 .twsk_unique = tcp_twsk_unique,
2090 .twsk_destructor= tcp_twsk_destructor,
2093 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
2095 struct dst_entry *dst = skb_dst(skb);
2098 sk->sk_rx_dst = dst;
2099 inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
2101 EXPORT_SYMBOL(inet_sk_rx_dst_set);
2103 const struct inet_connection_sock_af_ops ipv4_specific = {
2104 .queue_xmit = ip_queue_xmit,
2105 .send_check = tcp_v4_send_check,
2106 .rebuild_header = inet_sk_rebuild_header,
2107 .sk_rx_dst_set = inet_sk_rx_dst_set,
2108 .conn_request = tcp_v4_conn_request,
2109 .syn_recv_sock = tcp_v4_syn_recv_sock,
2110 .net_header_len = sizeof(struct iphdr),
2111 .setsockopt = ip_setsockopt,
2112 .getsockopt = ip_getsockopt,
2113 .addr2sockaddr = inet_csk_addr2sockaddr,
2114 .sockaddr_len = sizeof(struct sockaddr_in),
2115 .bind_conflict = inet_csk_bind_conflict,
2116 #ifdef CONFIG_COMPAT
2117 .compat_setsockopt = compat_ip_setsockopt,
2118 .compat_getsockopt = compat_ip_getsockopt,
2121 EXPORT_SYMBOL(ipv4_specific);
2123 #ifdef CONFIG_TCP_MD5SIG
2124 static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
2125 .md5_lookup = tcp_v4_md5_lookup,
2126 .calc_md5_hash = tcp_v4_md5_hash_skb,
2127 .md5_parse = tcp_v4_parse_md5_keys,
2131 /* NOTE: A lot of things set to zero explicitly by call to
2132 * sk_alloc() so need not be done here.
2134 static int tcp_v4_init_sock(struct sock *sk)
2136 struct inet_connection_sock *icsk = inet_csk(sk);
2140 icsk->icsk_af_ops = &ipv4_specific;
2142 #ifdef CONFIG_TCP_MD5SIG
2143 tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
2149 void tcp_v4_destroy_sock(struct sock *sk)
2151 struct tcp_sock *tp = tcp_sk(sk);
2153 tcp_clear_xmit_timers(sk);
2155 tcp_cleanup_congestion_control(sk);
2157 /* Cleanup up the write buffer. */
2158 tcp_write_queue_purge(sk);
2160 /* Cleans up our, hopefully empty, out_of_order_queue. */
2161 __skb_queue_purge(&tp->out_of_order_queue);
2163 #ifdef CONFIG_TCP_MD5SIG
2164 /* Clean up the MD5 key list, if any */
2165 if (tp->md5sig_info) {
2166 tcp_clear_md5_list(sk);
2167 kfree_rcu(tp->md5sig_info, rcu);
2168 tp->md5sig_info = NULL;
2172 #ifdef CONFIG_NET_DMA
2173 /* Cleans up our sk_async_wait_queue */
2174 __skb_queue_purge(&sk->sk_async_wait_queue);
2177 /* Clean prequeue, it must be empty really */
2178 __skb_queue_purge(&tp->ucopy.prequeue);
2180 /* Clean up a referenced TCP bind bucket. */
2181 if (inet_csk(sk)->icsk_bind_hash)
2184 BUG_ON(tp->fastopen_rsk != NULL);
2186 /* If socket is aborted during connect operation */
2187 tcp_free_fastopen_req(tp);
2189 sk_sockets_allocated_dec(sk);
2190 sock_release_memcg(sk);
2192 EXPORT_SYMBOL(tcp_v4_destroy_sock);
2194 #ifdef CONFIG_PROC_FS
2195 /* Proc filesystem TCP sock list dumping. */
2197 static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head)
2199 return hlist_nulls_empty(head) ? NULL :
2200 list_entry(head->first, struct inet_timewait_sock, tw_node);
2203 static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw)
2205 return !is_a_nulls(tw->tw_node.next) ?
2206 hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
2210 * Get next listener socket follow cur. If cur is NULL, get first socket
2211 * starting from bucket given in st->bucket; when st->bucket is zero the
2212 * very first socket in the hash table is returned.
2214 static void *listening_get_next(struct seq_file *seq, void *cur)
2216 struct inet_connection_sock *icsk;
2217 struct hlist_nulls_node *node;
2218 struct sock *sk = cur;
2219 struct inet_listen_hashbucket *ilb;
2220 struct tcp_iter_state *st = seq->private;
2221 struct net *net = seq_file_net(seq);
2224 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2225 spin_lock_bh(&ilb->lock);
2226 sk = sk_nulls_head(&ilb->head);
2230 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2234 if (st->state == TCP_SEQ_STATE_OPENREQ) {
2235 struct request_sock *req = cur;
2237 icsk = inet_csk(st->syn_wait_sk);
2241 if (req->rsk_ops->family == st->family) {
2247 if (++st->sbucket >= icsk->icsk_accept_queue.listen_opt->nr_table_entries)
2250 req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
2252 sk = sk_nulls_next(st->syn_wait_sk);
2253 st->state = TCP_SEQ_STATE_LISTENING;
2254 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2256 icsk = inet_csk(sk);
2257 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2258 if (reqsk_queue_len(&icsk->icsk_accept_queue))
2260 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2261 sk = sk_nulls_next(sk);
2264 sk_nulls_for_each_from(sk, node) {
2265 if (!net_eq(sock_net(sk), net))
2267 if (sk->sk_family == st->family) {
2271 icsk = inet_csk(sk);
2272 read_lock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2273 if (reqsk_queue_len(&icsk->icsk_accept_queue)) {
2275 st->uid = sock_i_uid(sk);
2276 st->syn_wait_sk = sk;
2277 st->state = TCP_SEQ_STATE_OPENREQ;
2281 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2283 spin_unlock_bh(&ilb->lock);
2285 if (++st->bucket < INET_LHTABLE_SIZE) {
2286 ilb = &tcp_hashinfo.listening_hash[st->bucket];
2287 spin_lock_bh(&ilb->lock);
2288 sk = sk_nulls_head(&ilb->head);
2296 static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
2298 struct tcp_iter_state *st = seq->private;
2303 rc = listening_get_next(seq, NULL);
2305 while (rc && *pos) {
2306 rc = listening_get_next(seq, rc);
2312 static inline bool empty_bucket(struct tcp_iter_state *st)
2314 return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) &&
2315 hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain);
2319 * Get first established socket starting from bucket given in st->bucket.
2320 * If st->bucket is zero, the very first socket in the hash is returned.
2322 static void *established_get_first(struct seq_file *seq)
2324 struct tcp_iter_state *st = seq->private;
2325 struct net *net = seq_file_net(seq);
2329 for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) {
2331 struct hlist_nulls_node *node;
2332 struct inet_timewait_sock *tw;
2333 spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
2335 /* Lockless fast path for the common case of empty buckets */
2336 if (empty_bucket(st))
2340 sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
2341 if (sk->sk_family != st->family ||
2342 !net_eq(sock_net(sk), net)) {
2348 st->state = TCP_SEQ_STATE_TIME_WAIT;
2349 inet_twsk_for_each(tw, node,
2350 &tcp_hashinfo.ehash[st->bucket].twchain) {
2351 if (tw->tw_family != st->family ||
2352 !net_eq(twsk_net(tw), net)) {
2358 spin_unlock_bh(lock);
2359 st->state = TCP_SEQ_STATE_ESTABLISHED;
2365 static void *established_get_next(struct seq_file *seq, void *cur)
2367 struct sock *sk = cur;
2368 struct inet_timewait_sock *tw;
2369 struct hlist_nulls_node *node;
2370 struct tcp_iter_state *st = seq->private;
2371 struct net *net = seq_file_net(seq);
2376 if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
2380 while (tw && (tw->tw_family != st->family || !net_eq(twsk_net(tw), net))) {
2387 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2388 st->state = TCP_SEQ_STATE_ESTABLISHED;
2390 /* Look for next non empty bucket */
2392 while (++st->bucket <= tcp_hashinfo.ehash_mask &&
2395 if (st->bucket > tcp_hashinfo.ehash_mask)
2398 spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2399 sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
2401 sk = sk_nulls_next(sk);
2403 sk_nulls_for_each_from(sk, node) {
2404 if (sk->sk_family == st->family && net_eq(sock_net(sk), net))
2408 st->state = TCP_SEQ_STATE_TIME_WAIT;
2409 tw = tw_head(&tcp_hashinfo.ehash[st->bucket].twchain);
2417 static void *established_get_idx(struct seq_file *seq, loff_t pos)
2419 struct tcp_iter_state *st = seq->private;
2423 rc = established_get_first(seq);
2426 rc = established_get_next(seq, rc);
2432 static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
2435 struct tcp_iter_state *st = seq->private;
2437 st->state = TCP_SEQ_STATE_LISTENING;
2438 rc = listening_get_idx(seq, &pos);
2441 st->state = TCP_SEQ_STATE_ESTABLISHED;
2442 rc = established_get_idx(seq, pos);
2448 static void *tcp_seek_last_pos(struct seq_file *seq)
2450 struct tcp_iter_state *st = seq->private;
2451 int offset = st->offset;
2452 int orig_num = st->num;
2455 switch (st->state) {
2456 case TCP_SEQ_STATE_OPENREQ:
2457 case TCP_SEQ_STATE_LISTENING:
2458 if (st->bucket >= INET_LHTABLE_SIZE)
2460 st->state = TCP_SEQ_STATE_LISTENING;
2461 rc = listening_get_next(seq, NULL);
2462 while (offset-- && rc)
2463 rc = listening_get_next(seq, rc);
2468 case TCP_SEQ_STATE_ESTABLISHED:
2469 case TCP_SEQ_STATE_TIME_WAIT:
2470 st->state = TCP_SEQ_STATE_ESTABLISHED;
2471 if (st->bucket > tcp_hashinfo.ehash_mask)
2473 rc = established_get_first(seq);
2474 while (offset-- && rc)
2475 rc = established_get_next(seq, rc);
2483 static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
2485 struct tcp_iter_state *st = seq->private;
2488 if (*pos && *pos == st->last_pos) {
2489 rc = tcp_seek_last_pos(seq);
2494 st->state = TCP_SEQ_STATE_LISTENING;
2498 rc = *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2501 st->last_pos = *pos;
2505 static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2507 struct tcp_iter_state *st = seq->private;
2510 if (v == SEQ_START_TOKEN) {
2511 rc = tcp_get_idx(seq, 0);
2515 switch (st->state) {
2516 case TCP_SEQ_STATE_OPENREQ:
2517 case TCP_SEQ_STATE_LISTENING:
2518 rc = listening_get_next(seq, v);
2520 st->state = TCP_SEQ_STATE_ESTABLISHED;
2523 rc = established_get_first(seq);
2526 case TCP_SEQ_STATE_ESTABLISHED:
2527 case TCP_SEQ_STATE_TIME_WAIT:
2528 rc = established_get_next(seq, v);
2533 st->last_pos = *pos;
2537 static void tcp_seq_stop(struct seq_file *seq, void *v)
2539 struct tcp_iter_state *st = seq->private;
2541 switch (st->state) {
2542 case TCP_SEQ_STATE_OPENREQ:
2544 struct inet_connection_sock *icsk = inet_csk(st->syn_wait_sk);
2545 read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
2547 case TCP_SEQ_STATE_LISTENING:
2548 if (v != SEQ_START_TOKEN)
2549 spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
2551 case TCP_SEQ_STATE_TIME_WAIT:
2552 case TCP_SEQ_STATE_ESTABLISHED:
2554 spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
2559 int tcp_seq_open(struct inode *inode, struct file *file)
2561 struct tcp_seq_afinfo *afinfo = PDE_DATA(inode);
2562 struct tcp_iter_state *s;
2565 err = seq_open_net(inode, file, &afinfo->seq_ops,
2566 sizeof(struct tcp_iter_state));
2570 s = ((struct seq_file *)file->private_data)->private;
2571 s->family = afinfo->family;
2575 EXPORT_SYMBOL(tcp_seq_open);
2577 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo)
2580 struct proc_dir_entry *p;
2582 afinfo->seq_ops.start = tcp_seq_start;
2583 afinfo->seq_ops.next = tcp_seq_next;
2584 afinfo->seq_ops.stop = tcp_seq_stop;
2586 p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
2587 afinfo->seq_fops, afinfo);
2592 EXPORT_SYMBOL(tcp_proc_register);
2594 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
2596 remove_proc_entry(afinfo->name, net->proc_net);
2598 EXPORT_SYMBOL(tcp_proc_unregister);
2600 static void get_openreq4(const struct sock *sk, const struct request_sock *req,
2601 struct seq_file *f, int i, kuid_t uid, int *len)
2603 const struct inet_request_sock *ireq = inet_rsk(req);
2604 long delta = req->expires - jiffies;
2606 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2607 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %pK%n",
2610 ntohs(inet_sk(sk)->inet_sport),
2612 ntohs(ireq->rmt_port),
2614 0, 0, /* could print option size, but that is af dependent. */
2615 1, /* timers active (only the expire timer) */
2616 jiffies_delta_to_clock_t(delta),
2618 from_kuid_munged(seq_user_ns(f), uid),
2619 0, /* non standard timer */
2620 0, /* open_requests have no inode */
2621 atomic_read(&sk->sk_refcnt),
2626 static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
2629 unsigned long timer_expires;
2630 const struct tcp_sock *tp = tcp_sk(sk);
2631 const struct inet_connection_sock *icsk = inet_csk(sk);
2632 const struct inet_sock *inet = inet_sk(sk);
2633 struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;
2634 __be32 dest = inet->inet_daddr;
2635 __be32 src = inet->inet_rcv_saddr;
2636 __u16 destp = ntohs(inet->inet_dport);
2637 __u16 srcp = ntohs(inet->inet_sport);
2640 if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
2641 icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
2642 icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
2644 timer_expires = icsk->icsk_timeout;
2645 } else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
2647 timer_expires = icsk->icsk_timeout;
2648 } else if (timer_pending(&sk->sk_timer)) {
2650 timer_expires = sk->sk_timer.expires;
2653 timer_expires = jiffies;
2656 if (sk->sk_state == TCP_LISTEN)
2657 rx_queue = sk->sk_ack_backlog;
2660 * because we dont lock socket, we might find a transient negative value
2662 rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
2664 seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
2665 "%08X %5d %8d %lu %d %pK %lu %lu %u %u %d%n",
2666 i, src, srcp, dest, destp, sk->sk_state,
2667 tp->write_seq - tp->snd_una,
2670 jiffies_delta_to_clock_t(timer_expires - jiffies),
2671 icsk->icsk_retransmits,
2672 from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
2673 icsk->icsk_probes_out,
2675 atomic_read(&sk->sk_refcnt), sk,
2676 jiffies_to_clock_t(icsk->icsk_rto),
2677 jiffies_to_clock_t(icsk->icsk_ack.ato),
2678 (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
2680 sk->sk_state == TCP_LISTEN ?
2681 (fastopenq ? fastopenq->max_qlen : 0) :
2682 (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
2686 static void get_timewait4_sock(const struct inet_timewait_sock *tw,
2687 struct seq_file *f, int i, int *len)
2691 long delta = tw->tw_ttd - jiffies;
2693 dest = tw->tw_daddr;
2694 src = tw->tw_rcv_saddr;
2695 destp = ntohs(tw->tw_dport);
2696 srcp = ntohs(tw->tw_sport);
2698 seq_printf(f, "%4d: %08X:%04X %08X:%04X"
2699 " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
2700 i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
2701 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
2702 atomic_read(&tw->tw_refcnt), tw, len);
2707 static int tcp4_seq_show(struct seq_file *seq, void *v)
2709 struct tcp_iter_state *st;
2712 if (v == SEQ_START_TOKEN) {
2713 seq_printf(seq, "%-*s\n", TMPSZ - 1,
2714 " sl local_address rem_address st tx_queue "
2715 "rx_queue tr tm->when retrnsmt uid timeout "
2721 switch (st->state) {
2722 case TCP_SEQ_STATE_LISTENING:
2723 case TCP_SEQ_STATE_ESTABLISHED:
2724 get_tcp4_sock(v, seq, st->num, &len);
2726 case TCP_SEQ_STATE_OPENREQ:
2727 get_openreq4(st->syn_wait_sk, v, seq, st->num, st->uid, &len);
2729 case TCP_SEQ_STATE_TIME_WAIT:
2730 get_timewait4_sock(v, seq, st->num, &len);
2733 seq_printf(seq, "%*s\n", TMPSZ - 1 - len, "");
2738 static const struct file_operations tcp_afinfo_seq_fops = {
2739 .owner = THIS_MODULE,
2740 .open = tcp_seq_open,
2742 .llseek = seq_lseek,
2743 .release = seq_release_net
2746 static struct tcp_seq_afinfo tcp4_seq_afinfo = {
2749 .seq_fops = &tcp_afinfo_seq_fops,
2751 .show = tcp4_seq_show,
2755 static int __net_init tcp4_proc_init_net(struct net *net)
2757 return tcp_proc_register(net, &tcp4_seq_afinfo);
2760 static void __net_exit tcp4_proc_exit_net(struct net *net)
2762 tcp_proc_unregister(net, &tcp4_seq_afinfo);
2765 static struct pernet_operations tcp4_net_ops = {
2766 .init = tcp4_proc_init_net,
2767 .exit = tcp4_proc_exit_net,
2770 int __init tcp4_proc_init(void)
2772 return register_pernet_subsys(&tcp4_net_ops);
2775 void tcp4_proc_exit(void)
2777 unregister_pernet_subsys(&tcp4_net_ops);
2779 #endif /* CONFIG_PROC_FS */
2781 struct proto tcp_prot = {
2783 .owner = THIS_MODULE,
2785 .connect = tcp_v4_connect,
2786 .disconnect = tcp_disconnect,
2787 .accept = inet_csk_accept,
2789 .init = tcp_v4_init_sock,
2790 .destroy = tcp_v4_destroy_sock,
2791 .shutdown = tcp_shutdown,
2792 .setsockopt = tcp_setsockopt,
2793 .getsockopt = tcp_getsockopt,
2794 .recvmsg = tcp_recvmsg,
2795 .sendmsg = tcp_sendmsg,
2796 .sendpage = tcp_sendpage,
2797 .backlog_rcv = tcp_v4_do_rcv,
2798 .release_cb = tcp_release_cb,
2799 .mtu_reduced = tcp_v4_mtu_reduced,
2801 .unhash = inet_unhash,
2802 .get_port = inet_csk_get_port,
2803 .enter_memory_pressure = tcp_enter_memory_pressure,
2804 .stream_memory_free = tcp_stream_memory_free,
2805 .sockets_allocated = &tcp_sockets_allocated,
2806 .orphan_count = &tcp_orphan_count,
2807 .memory_allocated = &tcp_memory_allocated,
2808 .memory_pressure = &tcp_memory_pressure,
2809 .sysctl_wmem = sysctl_tcp_wmem,
2810 .sysctl_rmem = sysctl_tcp_rmem,
2811 .max_header = MAX_TCP_HEADER,
2812 .obj_size = sizeof(struct tcp_sock),
2813 .slab_flags = SLAB_DESTROY_BY_RCU,
2814 .twsk_prot = &tcp_timewait_sock_ops,
2815 .rsk_prot = &tcp_request_sock_ops,
2816 .h.hashinfo = &tcp_hashinfo,
2817 .no_autobind = true,
2818 #ifdef CONFIG_COMPAT
2819 .compat_setsockopt = compat_tcp_setsockopt,
2820 .compat_getsockopt = compat_tcp_getsockopt,
2822 #ifdef CONFIG_MEMCG_KMEM
2823 .init_cgroup = tcp_init_cgroup,
2824 .destroy_cgroup = tcp_destroy_cgroup,
2825 .proto_cgroup = tcp_proto_cgroup,
2828 EXPORT_SYMBOL(tcp_prot);
2830 static int __net_init tcp_sk_init(struct net *net)
2832 net->ipv4.sysctl_tcp_ecn = 2;
2836 static void __net_exit tcp_sk_exit(struct net *net)
2840 static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
2842 inet_twsk_purge(&tcp_hashinfo, &tcp_death_row, AF_INET);
2845 static struct pernet_operations __net_initdata tcp_sk_ops = {
2846 .init = tcp_sk_init,
2847 .exit = tcp_sk_exit,
2848 .exit_batch = tcp_sk_exit_batch,
2851 void __init tcp_v4_init(void)
2853 inet_hashinfo_init(&tcp_hashinfo);
2854 if (register_pernet_subsys(&tcp_sk_ops))
2855 panic("Failed to create the TCP control socket.\n");