1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
6 #include <linux/module.h>
7 #include <linux/skbuff.h>
8 #include <asm/unaligned.h>
10 #include <net/netns/generic.h>
11 #include <linux/proc_fs.h>
13 #include <linux/netfilter_ipv6.h>
14 #include <linux/netfilter/nf_synproxy.h>
16 #include <net/netfilter/nf_conntrack.h>
17 #include <net/netfilter/nf_conntrack_ecache.h>
18 #include <net/netfilter/nf_conntrack_extend.h>
19 #include <net/netfilter/nf_conntrack_seqadj.h>
20 #include <net/netfilter/nf_conntrack_synproxy.h>
21 #include <net/netfilter/nf_conntrack_zones.h>
22 #include <net/netfilter/nf_synproxy.h>
24 unsigned int synproxy_net_id;
25 EXPORT_SYMBOL_GPL(synproxy_net_id);
28 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
29 const struct tcphdr *th, struct synproxy_options *opts)
31 int length = (th->doff * 4) - sizeof(*th);
34 if (unlikely(length < 0))
37 ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
63 if (opsize == TCPOLEN_MSS) {
64 opts->mss_option = get_unaligned_be16(ptr);
65 opts->options |= NF_SYNPROXY_OPT_MSS;
69 if (opsize == TCPOLEN_WINDOW) {
71 if (opts->wscale > TCP_MAX_WSCALE)
72 opts->wscale = TCP_MAX_WSCALE;
73 opts->options |= NF_SYNPROXY_OPT_WSCALE;
76 case TCPOPT_TIMESTAMP:
77 if (opsize == TCPOLEN_TIMESTAMP) {
78 opts->tsval = get_unaligned_be32(ptr);
79 opts->tsecr = get_unaligned_be32(ptr + 4);
80 opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
83 case TCPOPT_SACK_PERM:
84 if (opsize == TCPOLEN_SACK_PERM)
85 opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
95 EXPORT_SYMBOL_GPL(synproxy_parse_options);
98 synproxy_options_size(const struct synproxy_options *opts)
100 unsigned int size = 0;
102 if (opts->options & NF_SYNPROXY_OPT_MSS)
103 size += TCPOLEN_MSS_ALIGNED;
104 if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
105 size += TCPOLEN_TSTAMP_ALIGNED;
106 else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
107 size += TCPOLEN_SACKPERM_ALIGNED;
108 if (opts->options & NF_SYNPROXY_OPT_WSCALE)
109 size += TCPOLEN_WSCALE_ALIGNED;
115 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
117 __be32 *ptr = (__be32 *)(th + 1);
118 u8 options = opts->options;
120 if (options & NF_SYNPROXY_OPT_MSS)
121 *ptr++ = htonl((TCPOPT_MSS << 24) |
122 (TCPOLEN_MSS << 16) |
125 if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
126 if (options & NF_SYNPROXY_OPT_SACK_PERM)
127 *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
128 (TCPOLEN_SACK_PERM << 16) |
129 (TCPOPT_TIMESTAMP << 8) |
132 *ptr++ = htonl((TCPOPT_NOP << 24) |
134 (TCPOPT_TIMESTAMP << 8) |
137 *ptr++ = htonl(opts->tsval);
138 *ptr++ = htonl(opts->tsecr);
139 } else if (options & NF_SYNPROXY_OPT_SACK_PERM)
140 *ptr++ = htonl((TCPOPT_NOP << 24) |
142 (TCPOPT_SACK_PERM << 8) |
145 if (options & NF_SYNPROXY_OPT_WSCALE)
146 *ptr++ = htonl((TCPOPT_NOP << 24) |
147 (TCPOPT_WINDOW << 16) |
148 (TCPOLEN_WINDOW << 8) |
152 void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
153 struct synproxy_options *opts)
155 opts->tsecr = opts->tsval;
156 opts->tsval = tcp_time_stamp_raw() & ~0x3f;
158 if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
159 opts->tsval |= opts->wscale;
160 opts->wscale = info->wscale;
164 if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
165 opts->tsval |= 1 << 4;
167 if (opts->options & NF_SYNPROXY_OPT_ECN)
168 opts->tsval |= 1 << 5;
170 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
173 synproxy_check_timestamp_cookie(struct synproxy_options *opts)
175 opts->wscale = opts->tsecr & 0xf;
176 if (opts->wscale != 0xf)
177 opts->options |= NF_SYNPROXY_OPT_WSCALE;
179 opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
181 opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
185 synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
186 struct tcphdr *th, struct nf_conn *ct,
187 enum ip_conntrack_info ctinfo,
188 const struct nf_conn_synproxy *synproxy)
190 unsigned int optoff, optend;
193 if (synproxy->tsoff == 0)
196 optoff = protoff + sizeof(struct tcphdr);
197 optend = protoff + th->doff * 4;
199 if (skb_ensure_writable(skb, optend))
202 while (optoff < optend) {
203 unsigned char *op = skb->data + optoff;
212 if (optoff + 1 == optend ||
213 optoff + op[1] > optend ||
216 if (op[0] == TCPOPT_TIMESTAMP &&
217 op[1] == TCPOLEN_TIMESTAMP) {
218 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
219 ptr = (__be32 *)&op[2];
221 *ptr = htonl(ntohl(*ptr) -
224 ptr = (__be32 *)&op[6];
226 *ptr = htonl(ntohl(*ptr) +
229 inet_proto_csum_replace4(&th->check, skb,
239 #ifdef CONFIG_PROC_FS
240 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
242 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
246 return SEQ_START_TOKEN;
248 for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
249 if (!cpu_possible(cpu))
252 return per_cpu_ptr(snet->stats, cpu);
258 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
260 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
263 for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
264 if (!cpu_possible(cpu))
267 return per_cpu_ptr(snet->stats, cpu);
273 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
278 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
280 struct synproxy_stats *stats = v;
282 if (v == SEQ_START_TOKEN) {
283 seq_puts(seq, "entries\t\tsyn_received\t"
284 "cookie_invalid\tcookie_valid\t"
285 "cookie_retrans\tconn_reopened\n");
289 seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
291 stats->cookie_invalid,
293 stats->cookie_retrans,
294 stats->conn_reopened);
299 static const struct seq_operations synproxy_cpu_seq_ops = {
300 .start = synproxy_cpu_seq_start,
301 .next = synproxy_cpu_seq_next,
302 .stop = synproxy_cpu_seq_stop,
303 .show = synproxy_cpu_seq_show,
306 static int __net_init synproxy_proc_init(struct net *net)
308 if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
309 &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
314 static void __net_exit synproxy_proc_exit(struct net *net)
316 remove_proc_entry("synproxy", net->proc_net_stat);
319 static int __net_init synproxy_proc_init(struct net *net)
324 static void __net_exit synproxy_proc_exit(struct net *net)
328 #endif /* CONFIG_PROC_FS */
330 static int __net_init synproxy_net_init(struct net *net)
332 struct synproxy_net *snet = synproxy_pernet(net);
336 ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
340 if (!nfct_seqadj_ext_add(ct))
342 if (!nfct_synproxy_ext_add(ct))
345 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
348 snet->stats = alloc_percpu(struct synproxy_stats);
349 if (snet->stats == NULL)
352 err = synproxy_proc_init(net);
359 free_percpu(snet->stats);
366 static void __net_exit synproxy_net_exit(struct net *net)
368 struct synproxy_net *snet = synproxy_pernet(net);
370 nf_ct_put(snet->tmpl);
371 synproxy_proc_exit(net);
372 free_percpu(snet->stats);
375 static struct pernet_operations synproxy_net_ops = {
376 .init = synproxy_net_init,
377 .exit = synproxy_net_exit,
378 .id = &synproxy_net_id,
379 .size = sizeof(struct synproxy_net),
382 static int __init synproxy_core_init(void)
384 return register_pernet_subsys(&synproxy_net_ops);
387 static void __exit synproxy_core_exit(void)
389 unregister_pernet_subsys(&synproxy_net_ops);
392 module_init(synproxy_core_init);
393 module_exit(synproxy_core_exit);
395 static struct iphdr *
396 synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
401 skb_reset_network_header(skb);
402 iph = skb_put(skb, sizeof(*iph));
404 iph->ihl = sizeof(*iph) / 4;
407 iph->frag_off = htons(IP_DF);
408 iph->ttl = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
409 iph->protocol = IPPROTO_TCP;
418 synproxy_send_tcp(struct net *net,
419 const struct sk_buff *skb, struct sk_buff *nskb,
420 struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
421 struct iphdr *niph, struct tcphdr *nth,
422 unsigned int tcp_hdr_size)
424 nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
425 nskb->ip_summed = CHECKSUM_PARTIAL;
426 nskb->csum_start = (unsigned char *)nth - nskb->head;
427 nskb->csum_offset = offsetof(struct tcphdr, check);
429 skb_dst_set_noref(nskb, skb_dst(skb));
430 nskb->protocol = htons(ETH_P_IP);
431 if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC))
435 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
436 nf_conntrack_get(nfct);
439 ip_local_out(net, nskb->sk, nskb);
447 synproxy_send_client_synack(struct net *net,
448 const struct sk_buff *skb, const struct tcphdr *th,
449 const struct synproxy_options *opts)
451 struct sk_buff *nskb;
452 struct iphdr *iph, *niph;
454 unsigned int tcp_hdr_size;
455 u16 mss = opts->mss_encode;
459 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
460 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
464 skb_reserve(nskb, MAX_TCP_HEADER);
466 niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
468 skb_reset_transport_header(nskb);
469 nth = skb_put(nskb, tcp_hdr_size);
470 nth->source = th->dest;
471 nth->dest = th->source;
472 nth->seq = htonl(__cookie_v4_init_sequence(iph, th, &mss));
473 nth->ack_seq = htonl(ntohl(th->seq) + 1);
474 tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
475 if (opts->options & NF_SYNPROXY_OPT_ECN)
476 tcp_flag_word(nth) |= TCP_FLAG_ECE;
477 nth->doff = tcp_hdr_size / 4;
482 synproxy_build_options(nth, opts);
484 synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
485 IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
487 EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
490 synproxy_send_server_syn(struct net *net,
491 const struct sk_buff *skb, const struct tcphdr *th,
492 const struct synproxy_options *opts, u32 recv_seq)
494 struct synproxy_net *snet = synproxy_pernet(net);
495 struct sk_buff *nskb;
496 struct iphdr *iph, *niph;
498 unsigned int tcp_hdr_size;
502 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
503 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
507 skb_reserve(nskb, MAX_TCP_HEADER);
509 niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
511 skb_reset_transport_header(nskb);
512 nth = skb_put(nskb, tcp_hdr_size);
513 nth->source = th->source;
514 nth->dest = th->dest;
515 nth->seq = htonl(recv_seq - 1);
516 /* ack_seq is used to relay our ISN to the synproxy hook to initialize
517 * sequence number translation once a connection tracking entry exists.
519 nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
520 tcp_flag_word(nth) = TCP_FLAG_SYN;
521 if (opts->options & NF_SYNPROXY_OPT_ECN)
522 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
523 nth->doff = tcp_hdr_size / 4;
524 nth->window = th->window;
528 synproxy_build_options(nth, opts);
530 synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
531 niph, nth, tcp_hdr_size);
535 synproxy_send_server_ack(struct net *net,
536 const struct ip_ct_tcp *state,
537 const struct sk_buff *skb, const struct tcphdr *th,
538 const struct synproxy_options *opts)
540 struct sk_buff *nskb;
541 struct iphdr *iph, *niph;
543 unsigned int tcp_hdr_size;
547 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
548 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
552 skb_reserve(nskb, MAX_TCP_HEADER);
554 niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
556 skb_reset_transport_header(nskb);
557 nth = skb_put(nskb, tcp_hdr_size);
558 nth->source = th->dest;
559 nth->dest = th->source;
560 nth->seq = htonl(ntohl(th->ack_seq));
561 nth->ack_seq = htonl(ntohl(th->seq) + 1);
562 tcp_flag_word(nth) = TCP_FLAG_ACK;
563 nth->doff = tcp_hdr_size / 4;
564 nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
568 synproxy_build_options(nth, opts);
570 synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
574 synproxy_send_client_ack(struct net *net,
575 const struct sk_buff *skb, const struct tcphdr *th,
576 const struct synproxy_options *opts)
578 struct sk_buff *nskb;
579 struct iphdr *iph, *niph;
581 unsigned int tcp_hdr_size;
585 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
586 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
590 skb_reserve(nskb, MAX_TCP_HEADER);
592 niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
594 skb_reset_transport_header(nskb);
595 nth = skb_put(nskb, tcp_hdr_size);
596 nth->source = th->source;
597 nth->dest = th->dest;
598 nth->seq = htonl(ntohl(th->seq) + 1);
599 nth->ack_seq = th->ack_seq;
600 tcp_flag_word(nth) = TCP_FLAG_ACK;
601 nth->doff = tcp_hdr_size / 4;
602 nth->window = htons(ntohs(th->window) >> opts->wscale);
606 synproxy_build_options(nth, opts);
608 synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
609 IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
613 synproxy_recv_client_ack(struct net *net,
614 const struct sk_buff *skb, const struct tcphdr *th,
615 struct synproxy_options *opts, u32 recv_seq)
617 struct synproxy_net *snet = synproxy_pernet(net);
620 mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
622 this_cpu_inc(snet->stats->cookie_invalid);
626 this_cpu_inc(snet->stats->cookie_valid);
627 opts->mss_option = mss;
628 opts->options |= NF_SYNPROXY_OPT_MSS;
630 if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
631 synproxy_check_timestamp_cookie(opts);
633 synproxy_send_server_syn(net, skb, th, opts, recv_seq);
636 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
639 ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
640 const struct nf_hook_state *nhs)
642 struct net *net = nhs->net;
643 struct synproxy_net *snet = synproxy_pernet(net);
644 enum ip_conntrack_info ctinfo;
646 struct nf_conn_synproxy *synproxy;
647 struct synproxy_options opts = {};
648 const struct ip_ct_tcp *state;
649 struct tcphdr *th, _th;
652 ct = nf_ct_get(skb, &ctinfo);
656 synproxy = nfct_synproxy(ct);
660 if (nf_is_loopback_packet(skb) ||
661 ip_hdr(skb)->protocol != IPPROTO_TCP)
664 thoff = ip_hdrlen(skb);
665 th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
669 state = &ct->proto.tcp;
670 switch (state->state) {
671 case TCP_CONNTRACK_CLOSE:
672 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
673 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
678 if (!th->syn || th->ack ||
679 CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
682 /* Reopened connection - reset the sequence number and timestamp
683 * adjustments, they will get initialized once the connection is
686 nf_ct_seqadj_init(ct, ctinfo, 0);
688 this_cpu_inc(snet->stats->conn_reopened);
690 case TCP_CONNTRACK_SYN_SENT:
691 if (!synproxy_parse_options(skb, thoff, th, &opts))
694 if (!th->syn && th->ack &&
695 CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
696 /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
697 * therefore we need to add 1 to make the SYN sequence
698 * number match the one of first SYN.
700 if (synproxy_recv_client_ack(net, skb, th, &opts,
701 ntohl(th->seq) + 1)) {
702 this_cpu_inc(snet->stats->cookie_retrans);
710 synproxy->isn = ntohl(th->ack_seq);
711 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
712 synproxy->its = opts.tsecr;
714 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
716 case TCP_CONNTRACK_SYN_RECV:
717 if (!th->syn || !th->ack)
720 if (!synproxy_parse_options(skb, thoff, th, &opts))
723 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
724 synproxy->tsoff = opts.tsval - synproxy->its;
725 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
728 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
729 NF_SYNPROXY_OPT_WSCALE |
730 NF_SYNPROXY_OPT_SACK_PERM);
732 swap(opts.tsval, opts.tsecr);
733 synproxy_send_server_ack(net, state, skb, th, &opts);
735 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
736 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
738 swap(opts.tsval, opts.tsecr);
739 synproxy_send_client_ack(net, skb, th, &opts);
747 synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
750 EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
752 static const struct nf_hook_ops ipv4_synproxy_ops[] = {
754 .hook = ipv4_synproxy_hook,
756 .hooknum = NF_INET_LOCAL_IN,
757 .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
760 .hook = ipv4_synproxy_hook,
762 .hooknum = NF_INET_POST_ROUTING,
763 .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
767 int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
771 if (snet->hook_ref4 == 0) {
772 err = nf_register_net_hooks(net, ipv4_synproxy_ops,
773 ARRAY_SIZE(ipv4_synproxy_ops));
781 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
783 void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
786 if (snet->hook_ref4 == 0)
787 nf_unregister_net_hooks(net, ipv4_synproxy_ops,
788 ARRAY_SIZE(ipv4_synproxy_ops));
790 EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
792 #if IS_ENABLED(CONFIG_IPV6)
793 static struct ipv6hdr *
794 synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
795 const struct in6_addr *saddr,
796 const struct in6_addr *daddr)
800 skb_reset_network_header(skb);
801 iph = skb_put(skb, sizeof(*iph));
802 ip6_flow_hdr(iph, 0, 0);
803 iph->hop_limit = net->ipv6.devconf_all->hop_limit;
804 iph->nexthdr = IPPROTO_TCP;
812 synproxy_send_tcp_ipv6(struct net *net,
813 const struct sk_buff *skb, struct sk_buff *nskb,
814 struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
815 struct ipv6hdr *niph, struct tcphdr *nth,
816 unsigned int tcp_hdr_size)
818 struct dst_entry *dst;
822 nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
823 nskb->ip_summed = CHECKSUM_PARTIAL;
824 nskb->csum_start = (unsigned char *)nth - nskb->head;
825 nskb->csum_offset = offsetof(struct tcphdr, check);
827 memset(&fl6, 0, sizeof(fl6));
828 fl6.flowi6_proto = IPPROTO_TCP;
829 fl6.saddr = niph->saddr;
830 fl6.daddr = niph->daddr;
831 fl6.fl6_sport = nth->source;
832 fl6.fl6_dport = nth->dest;
833 security_skb_classify_flow((struct sk_buff *)skb,
834 flowi6_to_flowi_common(&fl6));
835 err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
840 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
844 skb_dst_set(nskb, dst);
847 nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
848 nf_conntrack_get(nfct);
851 ip6_local_out(net, nskb->sk, nskb);
859 synproxy_send_client_synack_ipv6(struct net *net,
860 const struct sk_buff *skb,
861 const struct tcphdr *th,
862 const struct synproxy_options *opts)
864 struct sk_buff *nskb;
865 struct ipv6hdr *iph, *niph;
867 unsigned int tcp_hdr_size;
868 u16 mss = opts->mss_encode;
872 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
873 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
877 skb_reserve(nskb, MAX_TCP_HEADER);
879 niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
881 skb_reset_transport_header(nskb);
882 nth = skb_put(nskb, tcp_hdr_size);
883 nth->source = th->dest;
884 nth->dest = th->source;
885 nth->seq = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss));
886 nth->ack_seq = htonl(ntohl(th->seq) + 1);
887 tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
888 if (opts->options & NF_SYNPROXY_OPT_ECN)
889 tcp_flag_word(nth) |= TCP_FLAG_ECE;
890 nth->doff = tcp_hdr_size / 4;
895 synproxy_build_options(nth, opts);
897 synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
898 IP_CT_ESTABLISHED_REPLY, niph, nth,
901 EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
904 synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb,
905 const struct tcphdr *th,
906 const struct synproxy_options *opts, u32 recv_seq)
908 struct synproxy_net *snet = synproxy_pernet(net);
909 struct sk_buff *nskb;
910 struct ipv6hdr *iph, *niph;
912 unsigned int tcp_hdr_size;
916 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
917 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
921 skb_reserve(nskb, MAX_TCP_HEADER);
923 niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
925 skb_reset_transport_header(nskb);
926 nth = skb_put(nskb, tcp_hdr_size);
927 nth->source = th->source;
928 nth->dest = th->dest;
929 nth->seq = htonl(recv_seq - 1);
930 /* ack_seq is used to relay our ISN to the synproxy hook to initialize
931 * sequence number translation once a connection tracking entry exists.
933 nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
934 tcp_flag_word(nth) = TCP_FLAG_SYN;
935 if (opts->options & NF_SYNPROXY_OPT_ECN)
936 tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
937 nth->doff = tcp_hdr_size / 4;
938 nth->window = th->window;
942 synproxy_build_options(nth, opts);
944 synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
945 IP_CT_NEW, niph, nth, tcp_hdr_size);
949 synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state,
950 const struct sk_buff *skb,
951 const struct tcphdr *th,
952 const struct synproxy_options *opts)
954 struct sk_buff *nskb;
955 struct ipv6hdr *iph, *niph;
957 unsigned int tcp_hdr_size;
961 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
962 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
966 skb_reserve(nskb, MAX_TCP_HEADER);
968 niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr);
970 skb_reset_transport_header(nskb);
971 nth = skb_put(nskb, tcp_hdr_size);
972 nth->source = th->dest;
973 nth->dest = th->source;
974 nth->seq = htonl(ntohl(th->ack_seq));
975 nth->ack_seq = htonl(ntohl(th->seq) + 1);
976 tcp_flag_word(nth) = TCP_FLAG_ACK;
977 nth->doff = tcp_hdr_size / 4;
978 nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
982 synproxy_build_options(nth, opts);
984 synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth,
989 synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
990 const struct tcphdr *th,
991 const struct synproxy_options *opts)
993 struct sk_buff *nskb;
994 struct ipv6hdr *iph, *niph;
996 unsigned int tcp_hdr_size;
1000 tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
1001 nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
1005 skb_reserve(nskb, MAX_TCP_HEADER);
1007 niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr);
1009 skb_reset_transport_header(nskb);
1010 nth = skb_put(nskb, tcp_hdr_size);
1011 nth->source = th->source;
1012 nth->dest = th->dest;
1013 nth->seq = htonl(ntohl(th->seq) + 1);
1014 nth->ack_seq = th->ack_seq;
1015 tcp_flag_word(nth) = TCP_FLAG_ACK;
1016 nth->doff = tcp_hdr_size / 4;
1017 nth->window = htons(ntohs(th->window) >> opts->wscale);
1021 synproxy_build_options(nth, opts);
1023 synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb),
1024 IP_CT_ESTABLISHED_REPLY, niph, nth,
1029 synproxy_recv_client_ack_ipv6(struct net *net,
1030 const struct sk_buff *skb,
1031 const struct tcphdr *th,
1032 struct synproxy_options *opts, u32 recv_seq)
1034 struct synproxy_net *snet = synproxy_pernet(net);
1037 mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
1039 this_cpu_inc(snet->stats->cookie_invalid);
1043 this_cpu_inc(snet->stats->cookie_valid);
1044 opts->mss_option = mss;
1045 opts->options |= NF_SYNPROXY_OPT_MSS;
1047 if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
1048 synproxy_check_timestamp_cookie(opts);
1050 synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
1053 EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
1056 ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
1057 const struct nf_hook_state *nhs)
1059 struct net *net = nhs->net;
1060 struct synproxy_net *snet = synproxy_pernet(net);
1061 enum ip_conntrack_info ctinfo;
1063 struct nf_conn_synproxy *synproxy;
1064 struct synproxy_options opts = {};
1065 const struct ip_ct_tcp *state;
1066 struct tcphdr *th, _th;
1071 ct = nf_ct_get(skb, &ctinfo);
1075 synproxy = nfct_synproxy(ct);
1079 if (nf_is_loopback_packet(skb))
1082 nexthdr = ipv6_hdr(skb)->nexthdr;
1083 thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
1085 if (thoff < 0 || nexthdr != IPPROTO_TCP)
1088 th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
1092 state = &ct->proto.tcp;
1093 switch (state->state) {
1094 case TCP_CONNTRACK_CLOSE:
1095 if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
1096 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
1097 ntohl(th->seq) + 1);
1101 if (!th->syn || th->ack ||
1102 CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1105 /* Reopened connection - reset the sequence number and timestamp
1106 * adjustments, they will get initialized once the connection is
1109 nf_ct_seqadj_init(ct, ctinfo, 0);
1110 synproxy->tsoff = 0;
1111 this_cpu_inc(snet->stats->conn_reopened);
1113 case TCP_CONNTRACK_SYN_SENT:
1114 if (!synproxy_parse_options(skb, thoff, th, &opts))
1117 if (!th->syn && th->ack &&
1118 CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
1119 /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
1120 * therefore we need to add 1 to make the SYN sequence
1121 * number match the one of first SYN.
1123 if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
1124 ntohl(th->seq) + 1)) {
1125 this_cpu_inc(snet->stats->cookie_retrans);
1133 synproxy->isn = ntohl(th->ack_seq);
1134 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP)
1135 synproxy->its = opts.tsecr;
1137 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1139 case TCP_CONNTRACK_SYN_RECV:
1140 if (!th->syn || !th->ack)
1143 if (!synproxy_parse_options(skb, thoff, th, &opts))
1146 if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) {
1147 synproxy->tsoff = opts.tsval - synproxy->its;
1148 nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
1151 opts.options &= ~(NF_SYNPROXY_OPT_MSS |
1152 NF_SYNPROXY_OPT_WSCALE |
1153 NF_SYNPROXY_OPT_SACK_PERM);
1155 swap(opts.tsval, opts.tsecr);
1156 synproxy_send_server_ack_ipv6(net, state, skb, th, &opts);
1158 nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
1159 nf_conntrack_event_cache(IPCT_SEQADJ, ct);
1161 swap(opts.tsval, opts.tsecr);
1162 synproxy_send_client_ack_ipv6(net, skb, th, &opts);
1170 synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
1173 EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
1175 static const struct nf_hook_ops ipv6_synproxy_ops[] = {
1177 .hook = ipv6_synproxy_hook,
1179 .hooknum = NF_INET_LOCAL_IN,
1180 .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1183 .hook = ipv6_synproxy_hook,
1185 .hooknum = NF_INET_POST_ROUTING,
1186 .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
1191 nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
1195 if (snet->hook_ref6 == 0) {
1196 err = nf_register_net_hooks(net, ipv6_synproxy_ops,
1197 ARRAY_SIZE(ipv6_synproxy_ops));
1205 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
1208 nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
1211 if (snet->hook_ref6 == 0)
1212 nf_unregister_net_hooks(net, ipv6_synproxy_ops,
1213 ARRAY_SIZE(ipv6_synproxy_ops));
1215 EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
1216 #endif /* CONFIG_IPV6 */
1218 MODULE_LICENSE("GPL");
1219 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
1220 MODULE_DESCRIPTION("nftables SYNPROXY expression support");