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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
48b1de4c PM |
2 | /* |
3 | * Copyright (c) 2013 Patrick McHardy <kaber@trash.net> | |
48b1de4c PM |
4 | */ |
5 | ||
6 | #include <linux/module.h> | |
7 | #include <linux/skbuff.h> | |
8 | #include <asm/unaligned.h> | |
9 | #include <net/tcp.h> | |
10 | #include <net/netns/generic.h> | |
10c04a8e | 11 | #include <linux/proc_fs.h> |
48b1de4c | 12 | |
d7f9b2f1 | 13 | #include <linux/netfilter_ipv6.h> |
f0c1aab2 | 14 | #include <linux/netfilter/nf_synproxy.h> |
308ac914 | 15 | |
48b1de4c | 16 | #include <net/netfilter/nf_conntrack.h> |
d7f9b2f1 | 17 | #include <net/netfilter/nf_conntrack_ecache.h> |
48b1de4c PM |
18 | #include <net/netfilter/nf_conntrack_extend.h> |
19 | #include <net/netfilter/nf_conntrack_seqadj.h> | |
20 | #include <net/netfilter/nf_conntrack_synproxy.h> | |
308ac914 | 21 | #include <net/netfilter/nf_conntrack_zones.h> |
d7f9b2f1 | 22 | #include <net/netfilter/nf_synproxy.h> |
48b1de4c | 23 | |
c7d03a00 | 24 | unsigned int synproxy_net_id; |
48b1de4c PM |
25 | EXPORT_SYMBOL_GPL(synproxy_net_id); |
26 | ||
f4a87e7b | 27 | bool |
48b1de4c PM |
28 | synproxy_parse_options(const struct sk_buff *skb, unsigned int doff, |
29 | const struct tcphdr *th, struct synproxy_options *opts) | |
30 | { | |
31 | int length = (th->doff * 4) - sizeof(*th); | |
32 | u8 buf[40], *ptr; | |
33 | ||
5fc177ab MM |
34 | if (unlikely(length < 0)) |
35 | return false; | |
36 | ||
48b1de4c | 37 | ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf); |
f4a87e7b PM |
38 | if (ptr == NULL) |
39 | return false; | |
48b1de4c PM |
40 | |
41 | opts->options = 0; | |
42 | while (length > 0) { | |
43 | int opcode = *ptr++; | |
44 | int opsize; | |
45 | ||
46 | switch (opcode) { | |
47 | case TCPOPT_EOL: | |
f4a87e7b | 48 | return true; |
48b1de4c PM |
49 | case TCPOPT_NOP: |
50 | length--; | |
51 | continue; | |
52 | default: | |
5fc177ab MM |
53 | if (length < 2) |
54 | return true; | |
48b1de4c PM |
55 | opsize = *ptr++; |
56 | if (opsize < 2) | |
f4a87e7b | 57 | return true; |
48b1de4c | 58 | if (opsize > length) |
f4a87e7b | 59 | return true; |
48b1de4c PM |
60 | |
61 | switch (opcode) { | |
62 | case TCPOPT_MSS: | |
63 | if (opsize == TCPOLEN_MSS) { | |
8c0bb787 | 64 | opts->mss_option = get_unaligned_be16(ptr); |
d7f9b2f1 | 65 | opts->options |= NF_SYNPROXY_OPT_MSS; |
48b1de4c PM |
66 | } |
67 | break; | |
68 | case TCPOPT_WINDOW: | |
69 | if (opsize == TCPOLEN_WINDOW) { | |
70 | opts->wscale = *ptr; | |
122868b3 GF |
71 | if (opts->wscale > TCP_MAX_WSCALE) |
72 | opts->wscale = TCP_MAX_WSCALE; | |
d7f9b2f1 | 73 | opts->options |= NF_SYNPROXY_OPT_WSCALE; |
48b1de4c PM |
74 | } |
75 | break; | |
76 | case TCPOPT_TIMESTAMP: | |
77 | if (opsize == TCPOLEN_TIMESTAMP) { | |
78 | opts->tsval = get_unaligned_be32(ptr); | |
79 | opts->tsecr = get_unaligned_be32(ptr + 4); | |
d7f9b2f1 | 80 | opts->options |= NF_SYNPROXY_OPT_TIMESTAMP; |
48b1de4c PM |
81 | } |
82 | break; | |
83 | case TCPOPT_SACK_PERM: | |
84 | if (opsize == TCPOLEN_SACK_PERM) | |
d7f9b2f1 | 85 | opts->options |= NF_SYNPROXY_OPT_SACK_PERM; |
48b1de4c PM |
86 | break; |
87 | } | |
88 | ||
89 | ptr += opsize - 2; | |
90 | length -= opsize; | |
91 | } | |
92 | } | |
f4a87e7b | 93 | return true; |
48b1de4c PM |
94 | } |
95 | EXPORT_SYMBOL_GPL(synproxy_parse_options); | |
96 | ||
d7f9b2f1 FFM |
97 | static unsigned int |
98 | synproxy_options_size(const struct synproxy_options *opts) | |
48b1de4c PM |
99 | { |
100 | unsigned int size = 0; | |
101 | ||
d7f9b2f1 | 102 | if (opts->options & NF_SYNPROXY_OPT_MSS) |
48b1de4c | 103 | size += TCPOLEN_MSS_ALIGNED; |
d7f9b2f1 | 104 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) |
48b1de4c | 105 | size += TCPOLEN_TSTAMP_ALIGNED; |
d7f9b2f1 | 106 | else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c | 107 | size += TCPOLEN_SACKPERM_ALIGNED; |
d7f9b2f1 | 108 | if (opts->options & NF_SYNPROXY_OPT_WSCALE) |
48b1de4c PM |
109 | size += TCPOLEN_WSCALE_ALIGNED; |
110 | ||
111 | return size; | |
112 | } | |
48b1de4c | 113 | |
d7f9b2f1 | 114 | static void |
48b1de4c PM |
115 | synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts) |
116 | { | |
117 | __be32 *ptr = (__be32 *)(th + 1); | |
118 | u8 options = opts->options; | |
119 | ||
d7f9b2f1 | 120 | if (options & NF_SYNPROXY_OPT_MSS) |
48b1de4c PM |
121 | *ptr++ = htonl((TCPOPT_MSS << 24) | |
122 | (TCPOLEN_MSS << 16) | | |
8c0bb787 | 123 | opts->mss_option); |
48b1de4c | 124 | |
d7f9b2f1 FFM |
125 | if (options & NF_SYNPROXY_OPT_TIMESTAMP) { |
126 | if (options & NF_SYNPROXY_OPT_SACK_PERM) | |
48b1de4c PM |
127 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
128 | (TCPOLEN_SACK_PERM << 16) | | |
129 | (TCPOPT_TIMESTAMP << 8) | | |
130 | TCPOLEN_TIMESTAMP); | |
131 | else | |
132 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
133 | (TCPOPT_NOP << 16) | | |
134 | (TCPOPT_TIMESTAMP << 8) | | |
135 | TCPOLEN_TIMESTAMP); | |
136 | ||
137 | *ptr++ = htonl(opts->tsval); | |
138 | *ptr++ = htonl(opts->tsecr); | |
d7f9b2f1 | 139 | } else if (options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c PM |
140 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
141 | (TCPOPT_NOP << 16) | | |
142 | (TCPOPT_SACK_PERM << 8) | | |
143 | TCPOLEN_SACK_PERM); | |
144 | ||
d7f9b2f1 | 145 | if (options & NF_SYNPROXY_OPT_WSCALE) |
48b1de4c PM |
146 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
147 | (TCPOPT_WINDOW << 16) | | |
148 | (TCPOLEN_WINDOW << 8) | | |
149 | opts->wscale); | |
150 | } | |
48b1de4c | 151 | |
d7f9b2f1 | 152 | void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info, |
48b1de4c PM |
153 | struct synproxy_options *opts) |
154 | { | |
155 | opts->tsecr = opts->tsval; | |
9a568de4 | 156 | opts->tsval = tcp_time_stamp_raw() & ~0x3f; |
48b1de4c | 157 | |
d7f9b2f1 | 158 | if (opts->options & NF_SYNPROXY_OPT_WSCALE) { |
c1898c4c MT |
159 | opts->tsval |= opts->wscale; |
160 | opts->wscale = info->wscale; | |
161 | } else | |
48b1de4c PM |
162 | opts->tsval |= 0xf; |
163 | ||
d7f9b2f1 | 164 | if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c PM |
165 | opts->tsval |= 1 << 4; |
166 | ||
d7f9b2f1 | 167 | if (opts->options & NF_SYNPROXY_OPT_ECN) |
48b1de4c PM |
168 | opts->tsval |= 1 << 5; |
169 | } | |
170 | EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie); | |
171 | ||
d7f9b2f1 FFM |
172 | static void |
173 | synproxy_check_timestamp_cookie(struct synproxy_options *opts) | |
48b1de4c PM |
174 | { |
175 | opts->wscale = opts->tsecr & 0xf; | |
176 | if (opts->wscale != 0xf) | |
d7f9b2f1 | 177 | opts->options |= NF_SYNPROXY_OPT_WSCALE; |
48b1de4c | 178 | |
d7f9b2f1 | 179 | opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0; |
48b1de4c | 180 | |
d7f9b2f1 | 181 | opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0; |
48b1de4c | 182 | } |
48b1de4c | 183 | |
d7f9b2f1 FFM |
184 | static unsigned int |
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) | |
48b1de4c PM |
189 | { |
190 | unsigned int optoff, optend; | |
851345c5 | 191 | __be32 *ptr, old; |
48b1de4c PM |
192 | |
193 | if (synproxy->tsoff == 0) | |
194 | return 1; | |
195 | ||
196 | optoff = protoff + sizeof(struct tcphdr); | |
197 | optend = protoff + th->doff * 4; | |
198 | ||
2cf6bffc | 199 | if (skb_ensure_writable(skb, optend)) |
48b1de4c PM |
200 | return 0; |
201 | ||
202 | while (optoff < optend) { | |
203 | unsigned char *op = skb->data + optoff; | |
204 | ||
205 | switch (op[0]) { | |
206 | case TCPOPT_EOL: | |
207 | return 1; | |
208 | case TCPOPT_NOP: | |
209 | optoff++; | |
210 | continue; | |
211 | default: | |
212 | if (optoff + 1 == optend || | |
213 | optoff + op[1] > optend || | |
214 | op[1] < 2) | |
215 | return 0; | |
216 | if (op[0] == TCPOPT_TIMESTAMP && | |
217 | op[1] == TCPOLEN_TIMESTAMP) { | |
218 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) { | |
851345c5 | 219 | ptr = (__be32 *)&op[2]; |
48b1de4c PM |
220 | old = *ptr; |
221 | *ptr = htonl(ntohl(*ptr) - | |
222 | synproxy->tsoff); | |
223 | } else { | |
851345c5 | 224 | ptr = (__be32 *)&op[6]; |
48b1de4c PM |
225 | old = *ptr; |
226 | *ptr = htonl(ntohl(*ptr) + | |
227 | synproxy->tsoff); | |
228 | } | |
229 | inet_proto_csum_replace4(&th->check, skb, | |
4b048d6d | 230 | old, *ptr, false); |
48b1de4c PM |
231 | return 1; |
232 | } | |
233 | optoff += op[1]; | |
234 | } | |
235 | } | |
236 | return 1; | |
237 | } | |
48b1de4c | 238 | |
48b1de4c PM |
239 | #ifdef CONFIG_PROC_FS |
240 | static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos) | |
241 | { | |
242 | struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq)); | |
243 | int cpu; | |
244 | ||
245 | if (*pos == 0) | |
246 | return SEQ_START_TOKEN; | |
247 | ||
248 | for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) { | |
249 | if (!cpu_possible(cpu)) | |
250 | continue; | |
251 | *pos = cpu + 1; | |
252 | return per_cpu_ptr(snet->stats, cpu); | |
253 | } | |
254 | ||
255 | return NULL; | |
256 | } | |
257 | ||
258 | static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
259 | { | |
260 | struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq)); | |
261 | int cpu; | |
262 | ||
263 | for (cpu = *pos; cpu < nr_cpu_ids; cpu++) { | |
264 | if (!cpu_possible(cpu)) | |
265 | continue; | |
266 | *pos = cpu + 1; | |
267 | return per_cpu_ptr(snet->stats, cpu); | |
268 | } | |
bb71f846 | 269 | (*pos)++; |
48b1de4c PM |
270 | return NULL; |
271 | } | |
272 | ||
273 | static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v) | |
274 | { | |
275 | return; | |
276 | } | |
277 | ||
278 | static int synproxy_cpu_seq_show(struct seq_file *seq, void *v) | |
279 | { | |
280 | struct synproxy_stats *stats = v; | |
281 | ||
282 | if (v == SEQ_START_TOKEN) { | |
cdec2685 | 283 | seq_puts(seq, "entries\t\tsyn_received\t" |
284 | "cookie_invalid\tcookie_valid\t" | |
285 | "cookie_retrans\tconn_reopened\n"); | |
48b1de4c PM |
286 | return 0; |
287 | } | |
288 | ||
289 | seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0, | |
290 | stats->syn_received, | |
291 | stats->cookie_invalid, | |
292 | stats->cookie_valid, | |
293 | stats->cookie_retrans, | |
294 | stats->conn_reopened); | |
295 | ||
296 | return 0; | |
297 | } | |
298 | ||
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, | |
304 | }; | |
305 | ||
48b1de4c PM |
306 | static int __net_init synproxy_proc_init(struct net *net) |
307 | { | |
c3506372 CH |
308 | if (!proc_create_net("synproxy", 0444, net->proc_net_stat, |
309 | &synproxy_cpu_seq_ops, sizeof(struct seq_net_private))) | |
48b1de4c PM |
310 | return -ENOMEM; |
311 | return 0; | |
312 | } | |
313 | ||
314 | static void __net_exit synproxy_proc_exit(struct net *net) | |
315 | { | |
316 | remove_proc_entry("synproxy", net->proc_net_stat); | |
317 | } | |
318 | #else | |
319 | static int __net_init synproxy_proc_init(struct net *net) | |
320 | { | |
321 | return 0; | |
322 | } | |
323 | ||
324 | static void __net_exit synproxy_proc_exit(struct net *net) | |
325 | { | |
326 | return; | |
327 | } | |
328 | #endif /* CONFIG_PROC_FS */ | |
329 | ||
330 | static int __net_init synproxy_net_init(struct net *net) | |
331 | { | |
332 | struct synproxy_net *snet = synproxy_pernet(net); | |
48b1de4c PM |
333 | struct nf_conn *ct; |
334 | int err = -ENOMEM; | |
335 | ||
308ac914 | 336 | ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL); |
1a727c63 | 337 | if (!ct) |
48b1de4c | 338 | goto err1; |
48b1de4c | 339 | |
48b1de4c PM |
340 | if (!nfct_seqadj_ext_add(ct)) |
341 | goto err2; | |
342 | if (!nfct_synproxy_ext_add(ct)) | |
343 | goto err2; | |
344 | ||
0838aa7f | 345 | __set_bit(IPS_CONFIRMED_BIT, &ct->status); |
48b1de4c PM |
346 | snet->tmpl = ct; |
347 | ||
348 | snet->stats = alloc_percpu(struct synproxy_stats); | |
349 | if (snet->stats == NULL) | |
350 | goto err2; | |
351 | ||
352 | err = synproxy_proc_init(net); | |
353 | if (err < 0) | |
354 | goto err3; | |
355 | ||
356 | return 0; | |
357 | ||
358 | err3: | |
359 | free_percpu(snet->stats); | |
360 | err2: | |
9cf94eab | 361 | nf_ct_tmpl_free(ct); |
48b1de4c PM |
362 | err1: |
363 | return err; | |
364 | } | |
365 | ||
366 | static void __net_exit synproxy_net_exit(struct net *net) | |
367 | { | |
368 | struct synproxy_net *snet = synproxy_pernet(net); | |
369 | ||
e53376be | 370 | nf_ct_put(snet->tmpl); |
48b1de4c PM |
371 | synproxy_proc_exit(net); |
372 | free_percpu(snet->stats); | |
373 | } | |
374 | ||
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), | |
380 | }; | |
381 | ||
382 | static int __init synproxy_core_init(void) | |
383 | { | |
1015c3de | 384 | return register_pernet_subsys(&synproxy_net_ops); |
48b1de4c PM |
385 | } |
386 | ||
387 | static void __exit synproxy_core_exit(void) | |
388 | { | |
389 | unregister_pernet_subsys(&synproxy_net_ops); | |
48b1de4c PM |
390 | } |
391 | ||
392 | module_init(synproxy_core_init); | |
393 | module_exit(synproxy_core_exit); | |
394 | ||
d7f9b2f1 FFM |
395 | static struct iphdr * |
396 | synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr, | |
397 | __be32 daddr) | |
398 | { | |
399 | struct iphdr *iph; | |
400 | ||
401 | skb_reset_network_header(skb); | |
402 | iph = skb_put(skb, sizeof(*iph)); | |
403 | iph->version = 4; | |
404 | iph->ihl = sizeof(*iph) / 4; | |
405 | iph->tos = 0; | |
406 | iph->id = 0; | |
407 | iph->frag_off = htons(IP_DF); | |
8281b7ec | 408 | iph->ttl = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); |
d7f9b2f1 FFM |
409 | iph->protocol = IPPROTO_TCP; |
410 | iph->check = 0; | |
411 | iph->saddr = saddr; | |
412 | iph->daddr = daddr; | |
413 | ||
414 | return iph; | |
415 | } | |
416 | ||
417 | static void | |
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) | |
423 | { | |
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); | |
428 | ||
429 | skb_dst_set_noref(nskb, skb_dst(skb)); | |
430 | nskb->protocol = htons(ETH_P_IP); | |
46d6c5ae | 431 | if (ip_route_me_harder(net, nskb->sk, nskb, RTN_UNSPEC)) |
d7f9b2f1 FFM |
432 | goto free_nskb; |
433 | ||
434 | if (nfct) { | |
435 | nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); | |
436 | nf_conntrack_get(nfct); | |
437 | } | |
438 | ||
439 | ip_local_out(net, nskb->sk, nskb); | |
440 | return; | |
441 | ||
442 | free_nskb: | |
443 | kfree_skb(nskb); | |
444 | } | |
445 | ||
446 | void | |
447 | synproxy_send_client_synack(struct net *net, | |
448 | const struct sk_buff *skb, const struct tcphdr *th, | |
449 | const struct synproxy_options *opts) | |
450 | { | |
451 | struct sk_buff *nskb; | |
452 | struct iphdr *iph, *niph; | |
453 | struct tcphdr *nth; | |
454 | unsigned int tcp_hdr_size; | |
b83329fb | 455 | u16 mss = opts->mss_encode; |
d7f9b2f1 FFM |
456 | |
457 | iph = ip_hdr(skb); | |
458 | ||
459 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
460 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
461 | GFP_ATOMIC); | |
462 | if (!nskb) | |
463 | return; | |
464 | skb_reserve(nskb, MAX_TCP_HEADER); | |
465 | ||
466 | niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); | |
467 | ||
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; | |
478 | nth->window = 0; | |
479 | nth->check = 0; | |
480 | nth->urg_ptr = 0; | |
481 | ||
482 | synproxy_build_options(nth, opts); | |
483 | ||
484 | synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), | |
485 | IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); | |
486 | } | |
487 | EXPORT_SYMBOL_GPL(synproxy_send_client_synack); | |
488 | ||
489 | static void | |
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) | |
493 | { | |
494 | struct synproxy_net *snet = synproxy_pernet(net); | |
495 | struct sk_buff *nskb; | |
496 | struct iphdr *iph, *niph; | |
497 | struct tcphdr *nth; | |
498 | unsigned int tcp_hdr_size; | |
499 | ||
500 | iph = ip_hdr(skb); | |
501 | ||
502 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
503 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
504 | GFP_ATOMIC); | |
505 | if (!nskb) | |
506 | return; | |
507 | skb_reserve(nskb, MAX_TCP_HEADER); | |
508 | ||
509 | niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); | |
510 | ||
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. | |
518 | */ | |
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; | |
525 | nth->check = 0; | |
526 | nth->urg_ptr = 0; | |
527 | ||
528 | synproxy_build_options(nth, opts); | |
529 | ||
530 | synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW, | |
531 | niph, nth, tcp_hdr_size); | |
532 | } | |
533 | ||
534 | static void | |
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) | |
539 | { | |
540 | struct sk_buff *nskb; | |
541 | struct iphdr *iph, *niph; | |
542 | struct tcphdr *nth; | |
543 | unsigned int tcp_hdr_size; | |
544 | ||
545 | iph = ip_hdr(skb); | |
546 | ||
547 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
548 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
549 | GFP_ATOMIC); | |
550 | if (!nskb) | |
551 | return; | |
552 | skb_reserve(nskb, MAX_TCP_HEADER); | |
553 | ||
554 | niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); | |
555 | ||
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); | |
565 | nth->check = 0; | |
566 | nth->urg_ptr = 0; | |
567 | ||
568 | synproxy_build_options(nth, opts); | |
569 | ||
570 | synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); | |
571 | } | |
572 | ||
573 | static void | |
574 | synproxy_send_client_ack(struct net *net, | |
575 | const struct sk_buff *skb, const struct tcphdr *th, | |
576 | const struct synproxy_options *opts) | |
577 | { | |
578 | struct sk_buff *nskb; | |
579 | struct iphdr *iph, *niph; | |
580 | struct tcphdr *nth; | |
581 | unsigned int tcp_hdr_size; | |
582 | ||
583 | iph = ip_hdr(skb); | |
584 | ||
585 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
586 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
587 | GFP_ATOMIC); | |
588 | if (!nskb) | |
589 | return; | |
590 | skb_reserve(nskb, MAX_TCP_HEADER); | |
591 | ||
592 | niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); | |
593 | ||
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); | |
603 | nth->check = 0; | |
604 | nth->urg_ptr = 0; | |
605 | ||
606 | synproxy_build_options(nth, opts); | |
607 | ||
608 | synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), | |
609 | IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); | |
610 | } | |
611 | ||
612 | bool | |
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) | |
616 | { | |
617 | struct synproxy_net *snet = synproxy_pernet(net); | |
618 | int mss; | |
619 | ||
620 | mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1); | |
621 | if (mss == 0) { | |
622 | this_cpu_inc(snet->stats->cookie_invalid); | |
623 | return false; | |
624 | } | |
625 | ||
626 | this_cpu_inc(snet->stats->cookie_valid); | |
8c0bb787 | 627 | opts->mss_option = mss; |
d7f9b2f1 FFM |
628 | opts->options |= NF_SYNPROXY_OPT_MSS; |
629 | ||
630 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) | |
631 | synproxy_check_timestamp_cookie(opts); | |
632 | ||
633 | synproxy_send_server_syn(net, skb, th, opts, recv_seq); | |
634 | return true; | |
635 | } | |
636 | EXPORT_SYMBOL_GPL(synproxy_recv_client_ack); | |
637 | ||
638 | unsigned int | |
639 | ipv4_synproxy_hook(void *priv, struct sk_buff *skb, | |
640 | const struct nf_hook_state *nhs) | |
641 | { | |
642 | struct net *net = nhs->net; | |
643 | struct synproxy_net *snet = synproxy_pernet(net); | |
644 | enum ip_conntrack_info ctinfo; | |
645 | struct nf_conn *ct; | |
646 | struct nf_conn_synproxy *synproxy; | |
647 | struct synproxy_options opts = {}; | |
648 | const struct ip_ct_tcp *state; | |
649 | struct tcphdr *th, _th; | |
650 | unsigned int thoff; | |
651 | ||
652 | ct = nf_ct_get(skb, &ctinfo); | |
653 | if (!ct) | |
654 | return NF_ACCEPT; | |
655 | ||
656 | synproxy = nfct_synproxy(ct); | |
657 | if (!synproxy) | |
658 | return NF_ACCEPT; | |
659 | ||
660 | if (nf_is_loopback_packet(skb) || | |
661 | ip_hdr(skb)->protocol != IPPROTO_TCP) | |
662 | return NF_ACCEPT; | |
663 | ||
664 | thoff = ip_hdrlen(skb); | |
665 | th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); | |
666 | if (!th) | |
667 | return NF_DROP; | |
668 | ||
669 | state = &ct->proto.tcp; | |
670 | switch (state->state) { | |
671 | case TCP_CONNTRACK_CLOSE: | |
e971ceb8 | 672 | if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { |
d7f9b2f1 FFM |
673 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - |
674 | ntohl(th->seq) + 1); | |
675 | break; | |
676 | } | |
677 | ||
678 | if (!th->syn || th->ack || | |
679 | CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
680 | break; | |
681 | ||
682 | /* Reopened connection - reset the sequence number and timestamp | |
683 | * adjustments, they will get initialized once the connection is | |
684 | * reestablished. | |
685 | */ | |
686 | nf_ct_seqadj_init(ct, ctinfo, 0); | |
687 | synproxy->tsoff = 0; | |
688 | this_cpu_inc(snet->stats->conn_reopened); | |
954d8297 | 689 | fallthrough; |
d7f9b2f1 FFM |
690 | case TCP_CONNTRACK_SYN_SENT: |
691 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
692 | return NF_DROP; | |
693 | ||
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. | |
699 | */ | |
700 | if (synproxy_recv_client_ack(net, skb, th, &opts, | |
701 | ntohl(th->seq) + 1)) { | |
702 | this_cpu_inc(snet->stats->cookie_retrans); | |
703 | consume_skb(skb); | |
704 | return NF_STOLEN; | |
705 | } else { | |
706 | return NF_DROP; | |
707 | } | |
708 | } | |
709 | ||
710 | synproxy->isn = ntohl(th->ack_seq); | |
711 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) | |
712 | synproxy->its = opts.tsecr; | |
713 | ||
714 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
715 | break; | |
716 | case TCP_CONNTRACK_SYN_RECV: | |
717 | if (!th->syn || !th->ack) | |
718 | break; | |
719 | ||
720 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
721 | return NF_DROP; | |
722 | ||
723 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { | |
724 | synproxy->tsoff = opts.tsval - synproxy->its; | |
725 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
726 | } | |
727 | ||
728 | opts.options &= ~(NF_SYNPROXY_OPT_MSS | | |
729 | NF_SYNPROXY_OPT_WSCALE | | |
730 | NF_SYNPROXY_OPT_SACK_PERM); | |
731 | ||
732 | swap(opts.tsval, opts.tsecr); | |
733 | synproxy_send_server_ack(net, state, skb, th, &opts); | |
734 | ||
735 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); | |
736 | nf_conntrack_event_cache(IPCT_SEQADJ, ct); | |
737 | ||
738 | swap(opts.tsval, opts.tsecr); | |
739 | synproxy_send_client_ack(net, skb, th, &opts); | |
740 | ||
741 | consume_skb(skb); | |
742 | return NF_STOLEN; | |
743 | default: | |
744 | break; | |
745 | } | |
746 | ||
747 | synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); | |
748 | return NF_ACCEPT; | |
749 | } | |
750 | EXPORT_SYMBOL_GPL(ipv4_synproxy_hook); | |
751 | ||
752 | static const struct nf_hook_ops ipv4_synproxy_ops[] = { | |
753 | { | |
754 | .hook = ipv4_synproxy_hook, | |
755 | .pf = NFPROTO_IPV4, | |
756 | .hooknum = NF_INET_LOCAL_IN, | |
757 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
758 | }, | |
759 | { | |
760 | .hook = ipv4_synproxy_hook, | |
761 | .pf = NFPROTO_IPV4, | |
762 | .hooknum = NF_INET_POST_ROUTING, | |
763 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
764 | }, | |
765 | }; | |
766 | ||
767 | int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net) | |
768 | { | |
769 | int err; | |
770 | ||
771 | if (snet->hook_ref4 == 0) { | |
772 | err = nf_register_net_hooks(net, ipv4_synproxy_ops, | |
773 | ARRAY_SIZE(ipv4_synproxy_ops)); | |
774 | if (err) | |
775 | return err; | |
776 | } | |
777 | ||
778 | snet->hook_ref4++; | |
72c5e118 | 779 | return 0; |
d7f9b2f1 FFM |
780 | } |
781 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init); | |
782 | ||
783 | void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net) | |
784 | { | |
785 | snet->hook_ref4--; | |
786 | if (snet->hook_ref4 == 0) | |
787 | nf_unregister_net_hooks(net, ipv4_synproxy_ops, | |
788 | ARRAY_SIZE(ipv4_synproxy_ops)); | |
789 | } | |
790 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini); | |
791 | ||
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) | |
797 | { | |
798 | struct ipv6hdr *iph; | |
799 | ||
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; | |
805 | iph->saddr = *saddr; | |
806 | iph->daddr = *daddr; | |
807 | ||
808 | return iph; | |
809 | } | |
810 | ||
811 | static void | |
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) | |
817 | { | |
818 | struct dst_entry *dst; | |
819 | struct flowi6 fl6; | |
820 | int err; | |
821 | ||
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); | |
826 | ||
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, | |
3df98d79 | 834 | flowi6_to_flowi_common(&fl6)); |
d7f9b2f1 FFM |
835 | err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false); |
836 | if (err) { | |
837 | goto free_nskb; | |
838 | } | |
839 | ||
840 | dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); | |
841 | if (IS_ERR(dst)) | |
842 | goto free_nskb; | |
843 | ||
844 | skb_dst_set(nskb, dst); | |
845 | ||
846 | if (nfct) { | |
847 | nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); | |
848 | nf_conntrack_get(nfct); | |
849 | } | |
850 | ||
851 | ip6_local_out(net, nskb->sk, nskb); | |
852 | return; | |
853 | ||
854 | free_nskb: | |
855 | kfree_skb(nskb); | |
856 | } | |
857 | ||
858 | void | |
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) | |
863 | { | |
864 | struct sk_buff *nskb; | |
865 | struct ipv6hdr *iph, *niph; | |
866 | struct tcphdr *nth; | |
867 | unsigned int tcp_hdr_size; | |
b83329fb | 868 | u16 mss = opts->mss_encode; |
d7f9b2f1 FFM |
869 | |
870 | iph = ipv6_hdr(skb); | |
871 | ||
872 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
873 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
874 | GFP_ATOMIC); | |
875 | if (!nskb) | |
876 | return; | |
877 | skb_reserve(nskb, MAX_TCP_HEADER); | |
878 | ||
879 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); | |
880 | ||
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; | |
891 | nth->window = 0; | |
892 | nth->check = 0; | |
893 | nth->urg_ptr = 0; | |
894 | ||
895 | synproxy_build_options(nth, opts); | |
896 | ||
897 | synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), | |
898 | IP_CT_ESTABLISHED_REPLY, niph, nth, | |
899 | tcp_hdr_size); | |
900 | } | |
901 | EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6); | |
902 | ||
903 | static void | |
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) | |
907 | { | |
908 | struct synproxy_net *snet = synproxy_pernet(net); | |
909 | struct sk_buff *nskb; | |
910 | struct ipv6hdr *iph, *niph; | |
911 | struct tcphdr *nth; | |
912 | unsigned int tcp_hdr_size; | |
913 | ||
914 | iph = ipv6_hdr(skb); | |
915 | ||
916 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
917 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
918 | GFP_ATOMIC); | |
919 | if (!nskb) | |
920 | return; | |
921 | skb_reserve(nskb, MAX_TCP_HEADER); | |
922 | ||
923 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); | |
924 | ||
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. | |
932 | */ | |
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; | |
939 | nth->check = 0; | |
940 | nth->urg_ptr = 0; | |
941 | ||
942 | synproxy_build_options(nth, opts); | |
943 | ||
944 | synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general, | |
945 | IP_CT_NEW, niph, nth, tcp_hdr_size); | |
946 | } | |
947 | ||
948 | static void | |
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) | |
953 | { | |
954 | struct sk_buff *nskb; | |
955 | struct ipv6hdr *iph, *niph; | |
956 | struct tcphdr *nth; | |
957 | unsigned int tcp_hdr_size; | |
958 | ||
959 | iph = ipv6_hdr(skb); | |
960 | ||
961 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
962 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
963 | GFP_ATOMIC); | |
964 | if (!nskb) | |
965 | return; | |
966 | skb_reserve(nskb, MAX_TCP_HEADER); | |
967 | ||
968 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); | |
969 | ||
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); | |
979 | nth->check = 0; | |
980 | nth->urg_ptr = 0; | |
981 | ||
982 | synproxy_build_options(nth, opts); | |
983 | ||
984 | synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth, | |
985 | tcp_hdr_size); | |
986 | } | |
987 | ||
988 | static void | |
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) | |
992 | { | |
993 | struct sk_buff *nskb; | |
994 | struct ipv6hdr *iph, *niph; | |
995 | struct tcphdr *nth; | |
996 | unsigned int tcp_hdr_size; | |
997 | ||
998 | iph = ipv6_hdr(skb); | |
999 | ||
1000 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
1001 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
1002 | GFP_ATOMIC); | |
1003 | if (!nskb) | |
1004 | return; | |
1005 | skb_reserve(nskb, MAX_TCP_HEADER); | |
1006 | ||
1007 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); | |
1008 | ||
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); | |
1018 | nth->check = 0; | |
1019 | nth->urg_ptr = 0; | |
1020 | ||
1021 | synproxy_build_options(nth, opts); | |
1022 | ||
1023 | synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), | |
1024 | IP_CT_ESTABLISHED_REPLY, niph, nth, | |
1025 | tcp_hdr_size); | |
1026 | } | |
1027 | ||
1028 | bool | |
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) | |
1033 | { | |
1034 | struct synproxy_net *snet = synproxy_pernet(net); | |
1035 | int mss; | |
1036 | ||
22f2efd3 | 1037 | mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1); |
d7f9b2f1 FFM |
1038 | if (mss == 0) { |
1039 | this_cpu_inc(snet->stats->cookie_invalid); | |
1040 | return false; | |
1041 | } | |
1042 | ||
1043 | this_cpu_inc(snet->stats->cookie_valid); | |
8c0bb787 | 1044 | opts->mss_option = mss; |
d7f9b2f1 FFM |
1045 | opts->options |= NF_SYNPROXY_OPT_MSS; |
1046 | ||
1047 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) | |
1048 | synproxy_check_timestamp_cookie(opts); | |
1049 | ||
1050 | synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq); | |
1051 | return true; | |
1052 | } | |
1053 | EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6); | |
1054 | ||
1055 | unsigned int | |
1056 | ipv6_synproxy_hook(void *priv, struct sk_buff *skb, | |
1057 | const struct nf_hook_state *nhs) | |
1058 | { | |
1059 | struct net *net = nhs->net; | |
1060 | struct synproxy_net *snet = synproxy_pernet(net); | |
1061 | enum ip_conntrack_info ctinfo; | |
1062 | struct nf_conn *ct; | |
1063 | struct nf_conn_synproxy *synproxy; | |
1064 | struct synproxy_options opts = {}; | |
1065 | const struct ip_ct_tcp *state; | |
1066 | struct tcphdr *th, _th; | |
1067 | __be16 frag_off; | |
1068 | u8 nexthdr; | |
1069 | int thoff; | |
1070 | ||
1071 | ct = nf_ct_get(skb, &ctinfo); | |
1072 | if (!ct) | |
1073 | return NF_ACCEPT; | |
1074 | ||
1075 | synproxy = nfct_synproxy(ct); | |
1076 | if (!synproxy) | |
1077 | return NF_ACCEPT; | |
1078 | ||
1079 | if (nf_is_loopback_packet(skb)) | |
1080 | return NF_ACCEPT; | |
1081 | ||
1082 | nexthdr = ipv6_hdr(skb)->nexthdr; | |
1083 | thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, | |
1084 | &frag_off); | |
1085 | if (thoff < 0 || nexthdr != IPPROTO_TCP) | |
1086 | return NF_ACCEPT; | |
1087 | ||
1088 | th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); | |
1089 | if (!th) | |
1090 | return NF_DROP; | |
1091 | ||
1092 | state = &ct->proto.tcp; | |
1093 | switch (state->state) { | |
1094 | case TCP_CONNTRACK_CLOSE: | |
e971ceb8 | 1095 | if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { |
d7f9b2f1 FFM |
1096 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - |
1097 | ntohl(th->seq) + 1); | |
1098 | break; | |
1099 | } | |
1100 | ||
1101 | if (!th->syn || th->ack || | |
1102 | CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
1103 | break; | |
1104 | ||
1105 | /* Reopened connection - reset the sequence number and timestamp | |
1106 | * adjustments, they will get initialized once the connection is | |
1107 | * reestablished. | |
1108 | */ | |
1109 | nf_ct_seqadj_init(ct, ctinfo, 0); | |
1110 | synproxy->tsoff = 0; | |
1111 | this_cpu_inc(snet->stats->conn_reopened); | |
954d8297 | 1112 | fallthrough; |
d7f9b2f1 FFM |
1113 | case TCP_CONNTRACK_SYN_SENT: |
1114 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
1115 | return NF_DROP; | |
1116 | ||
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. | |
1122 | */ | |
1123 | if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts, | |
1124 | ntohl(th->seq) + 1)) { | |
1125 | this_cpu_inc(snet->stats->cookie_retrans); | |
1126 | consume_skb(skb); | |
1127 | return NF_STOLEN; | |
1128 | } else { | |
1129 | return NF_DROP; | |
1130 | } | |
1131 | } | |
1132 | ||
1133 | synproxy->isn = ntohl(th->ack_seq); | |
1134 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) | |
1135 | synproxy->its = opts.tsecr; | |
1136 | ||
1137 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
1138 | break; | |
1139 | case TCP_CONNTRACK_SYN_RECV: | |
1140 | if (!th->syn || !th->ack) | |
1141 | break; | |
1142 | ||
1143 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
1144 | return NF_DROP; | |
1145 | ||
1146 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { | |
1147 | synproxy->tsoff = opts.tsval - synproxy->its; | |
1148 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
1149 | } | |
1150 | ||
1151 | opts.options &= ~(NF_SYNPROXY_OPT_MSS | | |
1152 | NF_SYNPROXY_OPT_WSCALE | | |
1153 | NF_SYNPROXY_OPT_SACK_PERM); | |
1154 | ||
1155 | swap(opts.tsval, opts.tsecr); | |
1156 | synproxy_send_server_ack_ipv6(net, state, skb, th, &opts); | |
1157 | ||
1158 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); | |
1159 | nf_conntrack_event_cache(IPCT_SEQADJ, ct); | |
1160 | ||
1161 | swap(opts.tsval, opts.tsecr); | |
1162 | synproxy_send_client_ack_ipv6(net, skb, th, &opts); | |
1163 | ||
1164 | consume_skb(skb); | |
1165 | return NF_STOLEN; | |
1166 | default: | |
1167 | break; | |
1168 | } | |
1169 | ||
1170 | synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); | |
1171 | return NF_ACCEPT; | |
1172 | } | |
1173 | EXPORT_SYMBOL_GPL(ipv6_synproxy_hook); | |
1174 | ||
1175 | static const struct nf_hook_ops ipv6_synproxy_ops[] = { | |
1176 | { | |
1177 | .hook = ipv6_synproxy_hook, | |
1178 | .pf = NFPROTO_IPV6, | |
1179 | .hooknum = NF_INET_LOCAL_IN, | |
1180 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
1181 | }, | |
1182 | { | |
1183 | .hook = ipv6_synproxy_hook, | |
1184 | .pf = NFPROTO_IPV6, | |
1185 | .hooknum = NF_INET_POST_ROUTING, | |
1186 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
1187 | }, | |
1188 | }; | |
1189 | ||
1190 | int | |
1191 | nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net) | |
1192 | { | |
1193 | int err; | |
1194 | ||
1195 | if (snet->hook_ref6 == 0) { | |
1196 | err = nf_register_net_hooks(net, ipv6_synproxy_ops, | |
1197 | ARRAY_SIZE(ipv6_synproxy_ops)); | |
1198 | if (err) | |
1199 | return err; | |
1200 | } | |
1201 | ||
1202 | snet->hook_ref6++; | |
72c5e118 | 1203 | return 0; |
d7f9b2f1 FFM |
1204 | } |
1205 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init); | |
1206 | ||
1207 | void | |
1208 | nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net) | |
1209 | { | |
1210 | snet->hook_ref6--; | |
1211 | if (snet->hook_ref6 == 0) | |
1212 | nf_unregister_net_hooks(net, ipv6_synproxy_ops, | |
1213 | ARRAY_SIZE(ipv6_synproxy_ops)); | |
1214 | } | |
1215 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini); | |
1216 | #endif /* CONFIG_IPV6 */ | |
1217 | ||
48b1de4c PM |
1218 | MODULE_LICENSE("GPL"); |
1219 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
4cacc395 | 1220 | MODULE_DESCRIPTION("nftables SYNPROXY expression support"); |