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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 | ||
34 | ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf); | |
f4a87e7b PM |
35 | if (ptr == NULL) |
36 | return false; | |
48b1de4c PM |
37 | |
38 | opts->options = 0; | |
39 | while (length > 0) { | |
40 | int opcode = *ptr++; | |
41 | int opsize; | |
42 | ||
43 | switch (opcode) { | |
44 | case TCPOPT_EOL: | |
f4a87e7b | 45 | return true; |
48b1de4c PM |
46 | case TCPOPT_NOP: |
47 | length--; | |
48 | continue; | |
49 | default: | |
50 | opsize = *ptr++; | |
51 | if (opsize < 2) | |
f4a87e7b | 52 | return true; |
48b1de4c | 53 | if (opsize > length) |
f4a87e7b | 54 | return true; |
48b1de4c PM |
55 | |
56 | switch (opcode) { | |
57 | case TCPOPT_MSS: | |
58 | if (opsize == TCPOLEN_MSS) { | |
8c0bb787 | 59 | opts->mss_option = get_unaligned_be16(ptr); |
d7f9b2f1 | 60 | opts->options |= NF_SYNPROXY_OPT_MSS; |
48b1de4c PM |
61 | } |
62 | break; | |
63 | case TCPOPT_WINDOW: | |
64 | if (opsize == TCPOLEN_WINDOW) { | |
65 | opts->wscale = *ptr; | |
122868b3 GF |
66 | if (opts->wscale > TCP_MAX_WSCALE) |
67 | opts->wscale = TCP_MAX_WSCALE; | |
d7f9b2f1 | 68 | opts->options |= NF_SYNPROXY_OPT_WSCALE; |
48b1de4c PM |
69 | } |
70 | break; | |
71 | case TCPOPT_TIMESTAMP: | |
72 | if (opsize == TCPOLEN_TIMESTAMP) { | |
73 | opts->tsval = get_unaligned_be32(ptr); | |
74 | opts->tsecr = get_unaligned_be32(ptr + 4); | |
d7f9b2f1 | 75 | opts->options |= NF_SYNPROXY_OPT_TIMESTAMP; |
48b1de4c PM |
76 | } |
77 | break; | |
78 | case TCPOPT_SACK_PERM: | |
79 | if (opsize == TCPOLEN_SACK_PERM) | |
d7f9b2f1 | 80 | opts->options |= NF_SYNPROXY_OPT_SACK_PERM; |
48b1de4c PM |
81 | break; |
82 | } | |
83 | ||
84 | ptr += opsize - 2; | |
85 | length -= opsize; | |
86 | } | |
87 | } | |
f4a87e7b | 88 | return true; |
48b1de4c PM |
89 | } |
90 | EXPORT_SYMBOL_GPL(synproxy_parse_options); | |
91 | ||
d7f9b2f1 FFM |
92 | static unsigned int |
93 | synproxy_options_size(const struct synproxy_options *opts) | |
48b1de4c PM |
94 | { |
95 | unsigned int size = 0; | |
96 | ||
d7f9b2f1 | 97 | if (opts->options & NF_SYNPROXY_OPT_MSS) |
48b1de4c | 98 | size += TCPOLEN_MSS_ALIGNED; |
d7f9b2f1 | 99 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) |
48b1de4c | 100 | size += TCPOLEN_TSTAMP_ALIGNED; |
d7f9b2f1 | 101 | else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c | 102 | size += TCPOLEN_SACKPERM_ALIGNED; |
d7f9b2f1 | 103 | if (opts->options & NF_SYNPROXY_OPT_WSCALE) |
48b1de4c PM |
104 | size += TCPOLEN_WSCALE_ALIGNED; |
105 | ||
106 | return size; | |
107 | } | |
48b1de4c | 108 | |
d7f9b2f1 | 109 | static void |
48b1de4c PM |
110 | synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts) |
111 | { | |
112 | __be32 *ptr = (__be32 *)(th + 1); | |
113 | u8 options = opts->options; | |
114 | ||
d7f9b2f1 | 115 | if (options & NF_SYNPROXY_OPT_MSS) |
48b1de4c PM |
116 | *ptr++ = htonl((TCPOPT_MSS << 24) | |
117 | (TCPOLEN_MSS << 16) | | |
8c0bb787 | 118 | opts->mss_option); |
48b1de4c | 119 | |
d7f9b2f1 FFM |
120 | if (options & NF_SYNPROXY_OPT_TIMESTAMP) { |
121 | if (options & NF_SYNPROXY_OPT_SACK_PERM) | |
48b1de4c PM |
122 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
123 | (TCPOLEN_SACK_PERM << 16) | | |
124 | (TCPOPT_TIMESTAMP << 8) | | |
125 | TCPOLEN_TIMESTAMP); | |
126 | else | |
127 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
128 | (TCPOPT_NOP << 16) | | |
129 | (TCPOPT_TIMESTAMP << 8) | | |
130 | TCPOLEN_TIMESTAMP); | |
131 | ||
132 | *ptr++ = htonl(opts->tsval); | |
133 | *ptr++ = htonl(opts->tsecr); | |
d7f9b2f1 | 134 | } else if (options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c PM |
135 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
136 | (TCPOPT_NOP << 16) | | |
137 | (TCPOPT_SACK_PERM << 8) | | |
138 | TCPOLEN_SACK_PERM); | |
139 | ||
d7f9b2f1 | 140 | if (options & NF_SYNPROXY_OPT_WSCALE) |
48b1de4c PM |
141 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
142 | (TCPOPT_WINDOW << 16) | | |
143 | (TCPOLEN_WINDOW << 8) | | |
144 | opts->wscale); | |
145 | } | |
48b1de4c | 146 | |
d7f9b2f1 | 147 | void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info, |
48b1de4c PM |
148 | struct synproxy_options *opts) |
149 | { | |
150 | opts->tsecr = opts->tsval; | |
9a568de4 | 151 | opts->tsval = tcp_time_stamp_raw() & ~0x3f; |
48b1de4c | 152 | |
d7f9b2f1 | 153 | if (opts->options & NF_SYNPROXY_OPT_WSCALE) { |
c1898c4c MT |
154 | opts->tsval |= opts->wscale; |
155 | opts->wscale = info->wscale; | |
156 | } else | |
48b1de4c PM |
157 | opts->tsval |= 0xf; |
158 | ||
d7f9b2f1 | 159 | if (opts->options & NF_SYNPROXY_OPT_SACK_PERM) |
48b1de4c PM |
160 | opts->tsval |= 1 << 4; |
161 | ||
d7f9b2f1 | 162 | if (opts->options & NF_SYNPROXY_OPT_ECN) |
48b1de4c PM |
163 | opts->tsval |= 1 << 5; |
164 | } | |
165 | EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie); | |
166 | ||
d7f9b2f1 FFM |
167 | static void |
168 | synproxy_check_timestamp_cookie(struct synproxy_options *opts) | |
48b1de4c PM |
169 | { |
170 | opts->wscale = opts->tsecr & 0xf; | |
171 | if (opts->wscale != 0xf) | |
d7f9b2f1 | 172 | opts->options |= NF_SYNPROXY_OPT_WSCALE; |
48b1de4c | 173 | |
d7f9b2f1 | 174 | opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0; |
48b1de4c | 175 | |
d7f9b2f1 | 176 | opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0; |
48b1de4c | 177 | } |
48b1de4c | 178 | |
d7f9b2f1 FFM |
179 | static unsigned int |
180 | synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff, | |
181 | struct tcphdr *th, struct nf_conn *ct, | |
182 | enum ip_conntrack_info ctinfo, | |
183 | const struct nf_conn_synproxy *synproxy) | |
48b1de4c PM |
184 | { |
185 | unsigned int optoff, optend; | |
851345c5 | 186 | __be32 *ptr, old; |
48b1de4c PM |
187 | |
188 | if (synproxy->tsoff == 0) | |
189 | return 1; | |
190 | ||
191 | optoff = protoff + sizeof(struct tcphdr); | |
192 | optend = protoff + th->doff * 4; | |
193 | ||
2cf6bffc | 194 | if (skb_ensure_writable(skb, optend)) |
48b1de4c PM |
195 | return 0; |
196 | ||
197 | while (optoff < optend) { | |
198 | unsigned char *op = skb->data + optoff; | |
199 | ||
200 | switch (op[0]) { | |
201 | case TCPOPT_EOL: | |
202 | return 1; | |
203 | case TCPOPT_NOP: | |
204 | optoff++; | |
205 | continue; | |
206 | default: | |
207 | if (optoff + 1 == optend || | |
208 | optoff + op[1] > optend || | |
209 | op[1] < 2) | |
210 | return 0; | |
211 | if (op[0] == TCPOPT_TIMESTAMP && | |
212 | op[1] == TCPOLEN_TIMESTAMP) { | |
213 | if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) { | |
851345c5 | 214 | ptr = (__be32 *)&op[2]; |
48b1de4c PM |
215 | old = *ptr; |
216 | *ptr = htonl(ntohl(*ptr) - | |
217 | synproxy->tsoff); | |
218 | } else { | |
851345c5 | 219 | ptr = (__be32 *)&op[6]; |
48b1de4c PM |
220 | old = *ptr; |
221 | *ptr = htonl(ntohl(*ptr) + | |
222 | synproxy->tsoff); | |
223 | } | |
224 | inet_proto_csum_replace4(&th->check, skb, | |
4b048d6d | 225 | old, *ptr, false); |
48b1de4c PM |
226 | return 1; |
227 | } | |
228 | optoff += op[1]; | |
229 | } | |
230 | } | |
231 | return 1; | |
232 | } | |
48b1de4c PM |
233 | |
234 | static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = { | |
235 | .len = sizeof(struct nf_conn_synproxy), | |
236 | .align = __alignof__(struct nf_conn_synproxy), | |
237 | .id = NF_CT_EXT_SYNPROXY, | |
238 | }; | |
239 | ||
240 | #ifdef CONFIG_PROC_FS | |
241 | static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos) | |
242 | { | |
243 | struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq)); | |
244 | int cpu; | |
245 | ||
246 | if (*pos == 0) | |
247 | return SEQ_START_TOKEN; | |
248 | ||
249 | for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) { | |
250 | if (!cpu_possible(cpu)) | |
251 | continue; | |
252 | *pos = cpu + 1; | |
253 | return per_cpu_ptr(snet->stats, cpu); | |
254 | } | |
255 | ||
256 | return NULL; | |
257 | } | |
258 | ||
259 | static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
260 | { | |
261 | struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq)); | |
262 | int cpu; | |
263 | ||
264 | for (cpu = *pos; cpu < nr_cpu_ids; cpu++) { | |
265 | if (!cpu_possible(cpu)) | |
266 | continue; | |
267 | *pos = cpu + 1; | |
268 | return per_cpu_ptr(snet->stats, cpu); | |
269 | } | |
bb71f846 | 270 | (*pos)++; |
48b1de4c PM |
271 | return NULL; |
272 | } | |
273 | ||
274 | static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v) | |
275 | { | |
276 | return; | |
277 | } | |
278 | ||
279 | static int synproxy_cpu_seq_show(struct seq_file *seq, void *v) | |
280 | { | |
281 | struct synproxy_stats *stats = v; | |
282 | ||
283 | if (v == SEQ_START_TOKEN) { | |
cdec2685 | 284 | seq_puts(seq, "entries\t\tsyn_received\t" |
285 | "cookie_invalid\tcookie_valid\t" | |
286 | "cookie_retrans\tconn_reopened\n"); | |
48b1de4c PM |
287 | return 0; |
288 | } | |
289 | ||
290 | seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0, | |
291 | stats->syn_received, | |
292 | stats->cookie_invalid, | |
293 | stats->cookie_valid, | |
294 | stats->cookie_retrans, | |
295 | stats->conn_reopened); | |
296 | ||
297 | return 0; | |
298 | } | |
299 | ||
300 | static const struct seq_operations synproxy_cpu_seq_ops = { | |
301 | .start = synproxy_cpu_seq_start, | |
302 | .next = synproxy_cpu_seq_next, | |
303 | .stop = synproxy_cpu_seq_stop, | |
304 | .show = synproxy_cpu_seq_show, | |
305 | }; | |
306 | ||
48b1de4c PM |
307 | static int __net_init synproxy_proc_init(struct net *net) |
308 | { | |
c3506372 CH |
309 | if (!proc_create_net("synproxy", 0444, net->proc_net_stat, |
310 | &synproxy_cpu_seq_ops, sizeof(struct seq_net_private))) | |
48b1de4c PM |
311 | return -ENOMEM; |
312 | return 0; | |
313 | } | |
314 | ||
315 | static void __net_exit synproxy_proc_exit(struct net *net) | |
316 | { | |
317 | remove_proc_entry("synproxy", net->proc_net_stat); | |
318 | } | |
319 | #else | |
320 | static int __net_init synproxy_proc_init(struct net *net) | |
321 | { | |
322 | return 0; | |
323 | } | |
324 | ||
325 | static void __net_exit synproxy_proc_exit(struct net *net) | |
326 | { | |
327 | return; | |
328 | } | |
329 | #endif /* CONFIG_PROC_FS */ | |
330 | ||
331 | static int __net_init synproxy_net_init(struct net *net) | |
332 | { | |
333 | struct synproxy_net *snet = synproxy_pernet(net); | |
48b1de4c PM |
334 | struct nf_conn *ct; |
335 | int err = -ENOMEM; | |
336 | ||
308ac914 | 337 | ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL); |
1a727c63 | 338 | if (!ct) |
48b1de4c | 339 | goto err1; |
48b1de4c | 340 | |
48b1de4c PM |
341 | if (!nfct_seqadj_ext_add(ct)) |
342 | goto err2; | |
343 | if (!nfct_synproxy_ext_add(ct)) | |
344 | goto err2; | |
345 | ||
0838aa7f PNA |
346 | __set_bit(IPS_CONFIRMED_BIT, &ct->status); |
347 | nf_conntrack_get(&ct->ct_general); | |
48b1de4c PM |
348 | snet->tmpl = ct; |
349 | ||
350 | snet->stats = alloc_percpu(struct synproxy_stats); | |
351 | if (snet->stats == NULL) | |
352 | goto err2; | |
353 | ||
354 | err = synproxy_proc_init(net); | |
355 | if (err < 0) | |
356 | goto err3; | |
357 | ||
358 | return 0; | |
359 | ||
360 | err3: | |
361 | free_percpu(snet->stats); | |
362 | err2: | |
9cf94eab | 363 | nf_ct_tmpl_free(ct); |
48b1de4c PM |
364 | err1: |
365 | return err; | |
366 | } | |
367 | ||
368 | static void __net_exit synproxy_net_exit(struct net *net) | |
369 | { | |
370 | struct synproxy_net *snet = synproxy_pernet(net); | |
371 | ||
e53376be | 372 | nf_ct_put(snet->tmpl); |
48b1de4c PM |
373 | synproxy_proc_exit(net); |
374 | free_percpu(snet->stats); | |
375 | } | |
376 | ||
377 | static struct pernet_operations synproxy_net_ops = { | |
378 | .init = synproxy_net_init, | |
379 | .exit = synproxy_net_exit, | |
380 | .id = &synproxy_net_id, | |
381 | .size = sizeof(struct synproxy_net), | |
382 | }; | |
383 | ||
384 | static int __init synproxy_core_init(void) | |
385 | { | |
386 | int err; | |
387 | ||
388 | err = nf_ct_extend_register(&nf_ct_synproxy_extend); | |
389 | if (err < 0) | |
390 | goto err1; | |
391 | ||
392 | err = register_pernet_subsys(&synproxy_net_ops); | |
393 | if (err < 0) | |
394 | goto err2; | |
395 | ||
396 | return 0; | |
397 | ||
398 | err2: | |
399 | nf_ct_extend_unregister(&nf_ct_synproxy_extend); | |
400 | err1: | |
401 | return err; | |
402 | } | |
403 | ||
404 | static void __exit synproxy_core_exit(void) | |
405 | { | |
406 | unregister_pernet_subsys(&synproxy_net_ops); | |
407 | nf_ct_extend_unregister(&nf_ct_synproxy_extend); | |
408 | } | |
409 | ||
410 | module_init(synproxy_core_init); | |
411 | module_exit(synproxy_core_exit); | |
412 | ||
d7f9b2f1 FFM |
413 | static struct iphdr * |
414 | synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr, | |
415 | __be32 daddr) | |
416 | { | |
417 | struct iphdr *iph; | |
418 | ||
419 | skb_reset_network_header(skb); | |
420 | iph = skb_put(skb, sizeof(*iph)); | |
421 | iph->version = 4; | |
422 | iph->ihl = sizeof(*iph) / 4; | |
423 | iph->tos = 0; | |
424 | iph->id = 0; | |
425 | iph->frag_off = htons(IP_DF); | |
426 | iph->ttl = net->ipv4.sysctl_ip_default_ttl; | |
427 | iph->protocol = IPPROTO_TCP; | |
428 | iph->check = 0; | |
429 | iph->saddr = saddr; | |
430 | iph->daddr = daddr; | |
431 | ||
432 | return iph; | |
433 | } | |
434 | ||
435 | static void | |
436 | synproxy_send_tcp(struct net *net, | |
437 | const struct sk_buff *skb, struct sk_buff *nskb, | |
438 | struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo, | |
439 | struct iphdr *niph, struct tcphdr *nth, | |
440 | unsigned int tcp_hdr_size) | |
441 | { | |
442 | nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0); | |
443 | nskb->ip_summed = CHECKSUM_PARTIAL; | |
444 | nskb->csum_start = (unsigned char *)nth - nskb->head; | |
445 | nskb->csum_offset = offsetof(struct tcphdr, check); | |
446 | ||
447 | skb_dst_set_noref(nskb, skb_dst(skb)); | |
448 | nskb->protocol = htons(ETH_P_IP); | |
449 | if (ip_route_me_harder(net, nskb, RTN_UNSPEC)) | |
450 | goto free_nskb; | |
451 | ||
452 | if (nfct) { | |
453 | nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); | |
454 | nf_conntrack_get(nfct); | |
455 | } | |
456 | ||
457 | ip_local_out(net, nskb->sk, nskb); | |
458 | return; | |
459 | ||
460 | free_nskb: | |
461 | kfree_skb(nskb); | |
462 | } | |
463 | ||
464 | void | |
465 | synproxy_send_client_synack(struct net *net, | |
466 | const struct sk_buff *skb, const struct tcphdr *th, | |
467 | const struct synproxy_options *opts) | |
468 | { | |
469 | struct sk_buff *nskb; | |
470 | struct iphdr *iph, *niph; | |
471 | struct tcphdr *nth; | |
472 | unsigned int tcp_hdr_size; | |
b83329fb | 473 | u16 mss = opts->mss_encode; |
d7f9b2f1 FFM |
474 | |
475 | iph = ip_hdr(skb); | |
476 | ||
477 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
478 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
479 | GFP_ATOMIC); | |
480 | if (!nskb) | |
481 | return; | |
482 | skb_reserve(nskb, MAX_TCP_HEADER); | |
483 | ||
484 | niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); | |
485 | ||
486 | skb_reset_transport_header(nskb); | |
487 | nth = skb_put(nskb, tcp_hdr_size); | |
488 | nth->source = th->dest; | |
489 | nth->dest = th->source; | |
490 | nth->seq = htonl(__cookie_v4_init_sequence(iph, th, &mss)); | |
491 | nth->ack_seq = htonl(ntohl(th->seq) + 1); | |
492 | tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK; | |
493 | if (opts->options & NF_SYNPROXY_OPT_ECN) | |
494 | tcp_flag_word(nth) |= TCP_FLAG_ECE; | |
495 | nth->doff = tcp_hdr_size / 4; | |
496 | nth->window = 0; | |
497 | nth->check = 0; | |
498 | nth->urg_ptr = 0; | |
499 | ||
500 | synproxy_build_options(nth, opts); | |
501 | ||
502 | synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), | |
503 | IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); | |
504 | } | |
505 | EXPORT_SYMBOL_GPL(synproxy_send_client_synack); | |
506 | ||
507 | static void | |
508 | synproxy_send_server_syn(struct net *net, | |
509 | const struct sk_buff *skb, const struct tcphdr *th, | |
510 | const struct synproxy_options *opts, u32 recv_seq) | |
511 | { | |
512 | struct synproxy_net *snet = synproxy_pernet(net); | |
513 | struct sk_buff *nskb; | |
514 | struct iphdr *iph, *niph; | |
515 | struct tcphdr *nth; | |
516 | unsigned int tcp_hdr_size; | |
517 | ||
518 | iph = ip_hdr(skb); | |
519 | ||
520 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
521 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
522 | GFP_ATOMIC); | |
523 | if (!nskb) | |
524 | return; | |
525 | skb_reserve(nskb, MAX_TCP_HEADER); | |
526 | ||
527 | niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); | |
528 | ||
529 | skb_reset_transport_header(nskb); | |
530 | nth = skb_put(nskb, tcp_hdr_size); | |
531 | nth->source = th->source; | |
532 | nth->dest = th->dest; | |
533 | nth->seq = htonl(recv_seq - 1); | |
534 | /* ack_seq is used to relay our ISN to the synproxy hook to initialize | |
535 | * sequence number translation once a connection tracking entry exists. | |
536 | */ | |
537 | nth->ack_seq = htonl(ntohl(th->ack_seq) - 1); | |
538 | tcp_flag_word(nth) = TCP_FLAG_SYN; | |
539 | if (opts->options & NF_SYNPROXY_OPT_ECN) | |
540 | tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR; | |
541 | nth->doff = tcp_hdr_size / 4; | |
542 | nth->window = th->window; | |
543 | nth->check = 0; | |
544 | nth->urg_ptr = 0; | |
545 | ||
546 | synproxy_build_options(nth, opts); | |
547 | ||
548 | synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW, | |
549 | niph, nth, tcp_hdr_size); | |
550 | } | |
551 | ||
552 | static void | |
553 | synproxy_send_server_ack(struct net *net, | |
554 | const struct ip_ct_tcp *state, | |
555 | const struct sk_buff *skb, const struct tcphdr *th, | |
556 | const struct synproxy_options *opts) | |
557 | { | |
558 | struct sk_buff *nskb; | |
559 | struct iphdr *iph, *niph; | |
560 | struct tcphdr *nth; | |
561 | unsigned int tcp_hdr_size; | |
562 | ||
563 | iph = ip_hdr(skb); | |
564 | ||
565 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
566 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
567 | GFP_ATOMIC); | |
568 | if (!nskb) | |
569 | return; | |
570 | skb_reserve(nskb, MAX_TCP_HEADER); | |
571 | ||
572 | niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr); | |
573 | ||
574 | skb_reset_transport_header(nskb); | |
575 | nth = skb_put(nskb, tcp_hdr_size); | |
576 | nth->source = th->dest; | |
577 | nth->dest = th->source; | |
578 | nth->seq = htonl(ntohl(th->ack_seq)); | |
579 | nth->ack_seq = htonl(ntohl(th->seq) + 1); | |
580 | tcp_flag_word(nth) = TCP_FLAG_ACK; | |
581 | nth->doff = tcp_hdr_size / 4; | |
582 | nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin); | |
583 | nth->check = 0; | |
584 | nth->urg_ptr = 0; | |
585 | ||
586 | synproxy_build_options(nth, opts); | |
587 | ||
588 | synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); | |
589 | } | |
590 | ||
591 | static void | |
592 | synproxy_send_client_ack(struct net *net, | |
593 | const struct sk_buff *skb, const struct tcphdr *th, | |
594 | const struct synproxy_options *opts) | |
595 | { | |
596 | struct sk_buff *nskb; | |
597 | struct iphdr *iph, *niph; | |
598 | struct tcphdr *nth; | |
599 | unsigned int tcp_hdr_size; | |
600 | ||
601 | iph = ip_hdr(skb); | |
602 | ||
603 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
604 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
605 | GFP_ATOMIC); | |
606 | if (!nskb) | |
607 | return; | |
608 | skb_reserve(nskb, MAX_TCP_HEADER); | |
609 | ||
610 | niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr); | |
611 | ||
612 | skb_reset_transport_header(nskb); | |
613 | nth = skb_put(nskb, tcp_hdr_size); | |
614 | nth->source = th->source; | |
615 | nth->dest = th->dest; | |
616 | nth->seq = htonl(ntohl(th->seq) + 1); | |
617 | nth->ack_seq = th->ack_seq; | |
618 | tcp_flag_word(nth) = TCP_FLAG_ACK; | |
619 | nth->doff = tcp_hdr_size / 4; | |
620 | nth->window = htons(ntohs(th->window) >> opts->wscale); | |
621 | nth->check = 0; | |
622 | nth->urg_ptr = 0; | |
623 | ||
624 | synproxy_build_options(nth, opts); | |
625 | ||
626 | synproxy_send_tcp(net, skb, nskb, skb_nfct(skb), | |
627 | IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size); | |
628 | } | |
629 | ||
630 | bool | |
631 | synproxy_recv_client_ack(struct net *net, | |
632 | const struct sk_buff *skb, const struct tcphdr *th, | |
633 | struct synproxy_options *opts, u32 recv_seq) | |
634 | { | |
635 | struct synproxy_net *snet = synproxy_pernet(net); | |
636 | int mss; | |
637 | ||
638 | mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1); | |
639 | if (mss == 0) { | |
640 | this_cpu_inc(snet->stats->cookie_invalid); | |
641 | return false; | |
642 | } | |
643 | ||
644 | this_cpu_inc(snet->stats->cookie_valid); | |
8c0bb787 | 645 | opts->mss_option = mss; |
d7f9b2f1 FFM |
646 | opts->options |= NF_SYNPROXY_OPT_MSS; |
647 | ||
648 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) | |
649 | synproxy_check_timestamp_cookie(opts); | |
650 | ||
651 | synproxy_send_server_syn(net, skb, th, opts, recv_seq); | |
652 | return true; | |
653 | } | |
654 | EXPORT_SYMBOL_GPL(synproxy_recv_client_ack); | |
655 | ||
656 | unsigned int | |
657 | ipv4_synproxy_hook(void *priv, struct sk_buff *skb, | |
658 | const struct nf_hook_state *nhs) | |
659 | { | |
660 | struct net *net = nhs->net; | |
661 | struct synproxy_net *snet = synproxy_pernet(net); | |
662 | enum ip_conntrack_info ctinfo; | |
663 | struct nf_conn *ct; | |
664 | struct nf_conn_synproxy *synproxy; | |
665 | struct synproxy_options opts = {}; | |
666 | const struct ip_ct_tcp *state; | |
667 | struct tcphdr *th, _th; | |
668 | unsigned int thoff; | |
669 | ||
670 | ct = nf_ct_get(skb, &ctinfo); | |
671 | if (!ct) | |
672 | return NF_ACCEPT; | |
673 | ||
674 | synproxy = nfct_synproxy(ct); | |
675 | if (!synproxy) | |
676 | return NF_ACCEPT; | |
677 | ||
678 | if (nf_is_loopback_packet(skb) || | |
679 | ip_hdr(skb)->protocol != IPPROTO_TCP) | |
680 | return NF_ACCEPT; | |
681 | ||
682 | thoff = ip_hdrlen(skb); | |
683 | th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); | |
684 | if (!th) | |
685 | return NF_DROP; | |
686 | ||
687 | state = &ct->proto.tcp; | |
688 | switch (state->state) { | |
689 | case TCP_CONNTRACK_CLOSE: | |
e971ceb8 | 690 | if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { |
d7f9b2f1 FFM |
691 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - |
692 | ntohl(th->seq) + 1); | |
693 | break; | |
694 | } | |
695 | ||
696 | if (!th->syn || th->ack || | |
697 | CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
698 | break; | |
699 | ||
700 | /* Reopened connection - reset the sequence number and timestamp | |
701 | * adjustments, they will get initialized once the connection is | |
702 | * reestablished. | |
703 | */ | |
704 | nf_ct_seqadj_init(ct, ctinfo, 0); | |
705 | synproxy->tsoff = 0; | |
706 | this_cpu_inc(snet->stats->conn_reopened); | |
954d8297 | 707 | fallthrough; |
d7f9b2f1 FFM |
708 | case TCP_CONNTRACK_SYN_SENT: |
709 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
710 | return NF_DROP; | |
711 | ||
712 | if (!th->syn && th->ack && | |
713 | CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) { | |
714 | /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1, | |
715 | * therefore we need to add 1 to make the SYN sequence | |
716 | * number match the one of first SYN. | |
717 | */ | |
718 | if (synproxy_recv_client_ack(net, skb, th, &opts, | |
719 | ntohl(th->seq) + 1)) { | |
720 | this_cpu_inc(snet->stats->cookie_retrans); | |
721 | consume_skb(skb); | |
722 | return NF_STOLEN; | |
723 | } else { | |
724 | return NF_DROP; | |
725 | } | |
726 | } | |
727 | ||
728 | synproxy->isn = ntohl(th->ack_seq); | |
729 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) | |
730 | synproxy->its = opts.tsecr; | |
731 | ||
732 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
733 | break; | |
734 | case TCP_CONNTRACK_SYN_RECV: | |
735 | if (!th->syn || !th->ack) | |
736 | break; | |
737 | ||
738 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
739 | return NF_DROP; | |
740 | ||
741 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { | |
742 | synproxy->tsoff = opts.tsval - synproxy->its; | |
743 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
744 | } | |
745 | ||
746 | opts.options &= ~(NF_SYNPROXY_OPT_MSS | | |
747 | NF_SYNPROXY_OPT_WSCALE | | |
748 | NF_SYNPROXY_OPT_SACK_PERM); | |
749 | ||
750 | swap(opts.tsval, opts.tsecr); | |
751 | synproxy_send_server_ack(net, state, skb, th, &opts); | |
752 | ||
753 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); | |
754 | nf_conntrack_event_cache(IPCT_SEQADJ, ct); | |
755 | ||
756 | swap(opts.tsval, opts.tsecr); | |
757 | synproxy_send_client_ack(net, skb, th, &opts); | |
758 | ||
759 | consume_skb(skb); | |
760 | return NF_STOLEN; | |
761 | default: | |
762 | break; | |
763 | } | |
764 | ||
765 | synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); | |
766 | return NF_ACCEPT; | |
767 | } | |
768 | EXPORT_SYMBOL_GPL(ipv4_synproxy_hook); | |
769 | ||
770 | static const struct nf_hook_ops ipv4_synproxy_ops[] = { | |
771 | { | |
772 | .hook = ipv4_synproxy_hook, | |
773 | .pf = NFPROTO_IPV4, | |
774 | .hooknum = NF_INET_LOCAL_IN, | |
775 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
776 | }, | |
777 | { | |
778 | .hook = ipv4_synproxy_hook, | |
779 | .pf = NFPROTO_IPV4, | |
780 | .hooknum = NF_INET_POST_ROUTING, | |
781 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
782 | }, | |
783 | }; | |
784 | ||
785 | int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net) | |
786 | { | |
787 | int err; | |
788 | ||
789 | if (snet->hook_ref4 == 0) { | |
790 | err = nf_register_net_hooks(net, ipv4_synproxy_ops, | |
791 | ARRAY_SIZE(ipv4_synproxy_ops)); | |
792 | if (err) | |
793 | return err; | |
794 | } | |
795 | ||
796 | snet->hook_ref4++; | |
72c5e118 | 797 | return 0; |
d7f9b2f1 FFM |
798 | } |
799 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init); | |
800 | ||
801 | void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net) | |
802 | { | |
803 | snet->hook_ref4--; | |
804 | if (snet->hook_ref4 == 0) | |
805 | nf_unregister_net_hooks(net, ipv4_synproxy_ops, | |
806 | ARRAY_SIZE(ipv4_synproxy_ops)); | |
807 | } | |
808 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini); | |
809 | ||
810 | #if IS_ENABLED(CONFIG_IPV6) | |
811 | static struct ipv6hdr * | |
812 | synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb, | |
813 | const struct in6_addr *saddr, | |
814 | const struct in6_addr *daddr) | |
815 | { | |
816 | struct ipv6hdr *iph; | |
817 | ||
818 | skb_reset_network_header(skb); | |
819 | iph = skb_put(skb, sizeof(*iph)); | |
820 | ip6_flow_hdr(iph, 0, 0); | |
821 | iph->hop_limit = net->ipv6.devconf_all->hop_limit; | |
822 | iph->nexthdr = IPPROTO_TCP; | |
823 | iph->saddr = *saddr; | |
824 | iph->daddr = *daddr; | |
825 | ||
826 | return iph; | |
827 | } | |
828 | ||
829 | static void | |
830 | synproxy_send_tcp_ipv6(struct net *net, | |
831 | const struct sk_buff *skb, struct sk_buff *nskb, | |
832 | struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo, | |
833 | struct ipv6hdr *niph, struct tcphdr *nth, | |
834 | unsigned int tcp_hdr_size) | |
835 | { | |
836 | struct dst_entry *dst; | |
837 | struct flowi6 fl6; | |
838 | int err; | |
839 | ||
840 | nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0); | |
841 | nskb->ip_summed = CHECKSUM_PARTIAL; | |
842 | nskb->csum_start = (unsigned char *)nth - nskb->head; | |
843 | nskb->csum_offset = offsetof(struct tcphdr, check); | |
844 | ||
845 | memset(&fl6, 0, sizeof(fl6)); | |
846 | fl6.flowi6_proto = IPPROTO_TCP; | |
847 | fl6.saddr = niph->saddr; | |
848 | fl6.daddr = niph->daddr; | |
849 | fl6.fl6_sport = nth->source; | |
850 | fl6.fl6_dport = nth->dest; | |
851 | security_skb_classify_flow((struct sk_buff *)skb, | |
852 | flowi6_to_flowi(&fl6)); | |
853 | err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false); | |
854 | if (err) { | |
855 | goto free_nskb; | |
856 | } | |
857 | ||
858 | dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); | |
859 | if (IS_ERR(dst)) | |
860 | goto free_nskb; | |
861 | ||
862 | skb_dst_set(nskb, dst); | |
863 | ||
864 | if (nfct) { | |
865 | nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo); | |
866 | nf_conntrack_get(nfct); | |
867 | } | |
868 | ||
869 | ip6_local_out(net, nskb->sk, nskb); | |
870 | return; | |
871 | ||
872 | free_nskb: | |
873 | kfree_skb(nskb); | |
874 | } | |
875 | ||
876 | void | |
877 | synproxy_send_client_synack_ipv6(struct net *net, | |
878 | const struct sk_buff *skb, | |
879 | const struct tcphdr *th, | |
880 | const struct synproxy_options *opts) | |
881 | { | |
882 | struct sk_buff *nskb; | |
883 | struct ipv6hdr *iph, *niph; | |
884 | struct tcphdr *nth; | |
885 | unsigned int tcp_hdr_size; | |
b83329fb | 886 | u16 mss = opts->mss_encode; |
d7f9b2f1 FFM |
887 | |
888 | iph = ipv6_hdr(skb); | |
889 | ||
890 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
891 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
892 | GFP_ATOMIC); | |
893 | if (!nskb) | |
894 | return; | |
895 | skb_reserve(nskb, MAX_TCP_HEADER); | |
896 | ||
897 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); | |
898 | ||
899 | skb_reset_transport_header(nskb); | |
900 | nth = skb_put(nskb, tcp_hdr_size); | |
901 | nth->source = th->dest; | |
902 | nth->dest = th->source; | |
903 | nth->seq = htonl(nf_ipv6_cookie_init_sequence(iph, th, &mss)); | |
904 | nth->ack_seq = htonl(ntohl(th->seq) + 1); | |
905 | tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK; | |
906 | if (opts->options & NF_SYNPROXY_OPT_ECN) | |
907 | tcp_flag_word(nth) |= TCP_FLAG_ECE; | |
908 | nth->doff = tcp_hdr_size / 4; | |
909 | nth->window = 0; | |
910 | nth->check = 0; | |
911 | nth->urg_ptr = 0; | |
912 | ||
913 | synproxy_build_options(nth, opts); | |
914 | ||
915 | synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), | |
916 | IP_CT_ESTABLISHED_REPLY, niph, nth, | |
917 | tcp_hdr_size); | |
918 | } | |
919 | EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6); | |
920 | ||
921 | static void | |
922 | synproxy_send_server_syn_ipv6(struct net *net, const struct sk_buff *skb, | |
923 | const struct tcphdr *th, | |
924 | const struct synproxy_options *opts, u32 recv_seq) | |
925 | { | |
926 | struct synproxy_net *snet = synproxy_pernet(net); | |
927 | struct sk_buff *nskb; | |
928 | struct ipv6hdr *iph, *niph; | |
929 | struct tcphdr *nth; | |
930 | unsigned int tcp_hdr_size; | |
931 | ||
932 | iph = ipv6_hdr(skb); | |
933 | ||
934 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
935 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
936 | GFP_ATOMIC); | |
937 | if (!nskb) | |
938 | return; | |
939 | skb_reserve(nskb, MAX_TCP_HEADER); | |
940 | ||
941 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); | |
942 | ||
943 | skb_reset_transport_header(nskb); | |
944 | nth = skb_put(nskb, tcp_hdr_size); | |
945 | nth->source = th->source; | |
946 | nth->dest = th->dest; | |
947 | nth->seq = htonl(recv_seq - 1); | |
948 | /* ack_seq is used to relay our ISN to the synproxy hook to initialize | |
949 | * sequence number translation once a connection tracking entry exists. | |
950 | */ | |
951 | nth->ack_seq = htonl(ntohl(th->ack_seq) - 1); | |
952 | tcp_flag_word(nth) = TCP_FLAG_SYN; | |
953 | if (opts->options & NF_SYNPROXY_OPT_ECN) | |
954 | tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR; | |
955 | nth->doff = tcp_hdr_size / 4; | |
956 | nth->window = th->window; | |
957 | nth->check = 0; | |
958 | nth->urg_ptr = 0; | |
959 | ||
960 | synproxy_build_options(nth, opts); | |
961 | ||
962 | synproxy_send_tcp_ipv6(net, skb, nskb, &snet->tmpl->ct_general, | |
963 | IP_CT_NEW, niph, nth, tcp_hdr_size); | |
964 | } | |
965 | ||
966 | static void | |
967 | synproxy_send_server_ack_ipv6(struct net *net, const struct ip_ct_tcp *state, | |
968 | const struct sk_buff *skb, | |
969 | const struct tcphdr *th, | |
970 | const struct synproxy_options *opts) | |
971 | { | |
972 | struct sk_buff *nskb; | |
973 | struct ipv6hdr *iph, *niph; | |
974 | struct tcphdr *nth; | |
975 | unsigned int tcp_hdr_size; | |
976 | ||
977 | iph = ipv6_hdr(skb); | |
978 | ||
979 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
980 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
981 | GFP_ATOMIC); | |
982 | if (!nskb) | |
983 | return; | |
984 | skb_reserve(nskb, MAX_TCP_HEADER); | |
985 | ||
986 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->daddr, &iph->saddr); | |
987 | ||
988 | skb_reset_transport_header(nskb); | |
989 | nth = skb_put(nskb, tcp_hdr_size); | |
990 | nth->source = th->dest; | |
991 | nth->dest = th->source; | |
992 | nth->seq = htonl(ntohl(th->ack_seq)); | |
993 | nth->ack_seq = htonl(ntohl(th->seq) + 1); | |
994 | tcp_flag_word(nth) = TCP_FLAG_ACK; | |
995 | nth->doff = tcp_hdr_size / 4; | |
996 | nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin); | |
997 | nth->check = 0; | |
998 | nth->urg_ptr = 0; | |
999 | ||
1000 | synproxy_build_options(nth, opts); | |
1001 | ||
1002 | synproxy_send_tcp_ipv6(net, skb, nskb, NULL, 0, niph, nth, | |
1003 | tcp_hdr_size); | |
1004 | } | |
1005 | ||
1006 | static void | |
1007 | synproxy_send_client_ack_ipv6(struct net *net, const struct sk_buff *skb, | |
1008 | const struct tcphdr *th, | |
1009 | const struct synproxy_options *opts) | |
1010 | { | |
1011 | struct sk_buff *nskb; | |
1012 | struct ipv6hdr *iph, *niph; | |
1013 | struct tcphdr *nth; | |
1014 | unsigned int tcp_hdr_size; | |
1015 | ||
1016 | iph = ipv6_hdr(skb); | |
1017 | ||
1018 | tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts); | |
1019 | nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER, | |
1020 | GFP_ATOMIC); | |
1021 | if (!nskb) | |
1022 | return; | |
1023 | skb_reserve(nskb, MAX_TCP_HEADER); | |
1024 | ||
1025 | niph = synproxy_build_ip_ipv6(net, nskb, &iph->saddr, &iph->daddr); | |
1026 | ||
1027 | skb_reset_transport_header(nskb); | |
1028 | nth = skb_put(nskb, tcp_hdr_size); | |
1029 | nth->source = th->source; | |
1030 | nth->dest = th->dest; | |
1031 | nth->seq = htonl(ntohl(th->seq) + 1); | |
1032 | nth->ack_seq = th->ack_seq; | |
1033 | tcp_flag_word(nth) = TCP_FLAG_ACK; | |
1034 | nth->doff = tcp_hdr_size / 4; | |
1035 | nth->window = htons(ntohs(th->window) >> opts->wscale); | |
1036 | nth->check = 0; | |
1037 | nth->urg_ptr = 0; | |
1038 | ||
1039 | synproxy_build_options(nth, opts); | |
1040 | ||
1041 | synproxy_send_tcp_ipv6(net, skb, nskb, skb_nfct(skb), | |
1042 | IP_CT_ESTABLISHED_REPLY, niph, nth, | |
1043 | tcp_hdr_size); | |
1044 | } | |
1045 | ||
1046 | bool | |
1047 | synproxy_recv_client_ack_ipv6(struct net *net, | |
1048 | const struct sk_buff *skb, | |
1049 | const struct tcphdr *th, | |
1050 | struct synproxy_options *opts, u32 recv_seq) | |
1051 | { | |
1052 | struct synproxy_net *snet = synproxy_pernet(net); | |
1053 | int mss; | |
1054 | ||
22f2efd3 | 1055 | mss = nf_cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1); |
d7f9b2f1 FFM |
1056 | if (mss == 0) { |
1057 | this_cpu_inc(snet->stats->cookie_invalid); | |
1058 | return false; | |
1059 | } | |
1060 | ||
1061 | this_cpu_inc(snet->stats->cookie_valid); | |
8c0bb787 | 1062 | opts->mss_option = mss; |
d7f9b2f1 FFM |
1063 | opts->options |= NF_SYNPROXY_OPT_MSS; |
1064 | ||
1065 | if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP) | |
1066 | synproxy_check_timestamp_cookie(opts); | |
1067 | ||
1068 | synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq); | |
1069 | return true; | |
1070 | } | |
1071 | EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6); | |
1072 | ||
1073 | unsigned int | |
1074 | ipv6_synproxy_hook(void *priv, struct sk_buff *skb, | |
1075 | const struct nf_hook_state *nhs) | |
1076 | { | |
1077 | struct net *net = nhs->net; | |
1078 | struct synproxy_net *snet = synproxy_pernet(net); | |
1079 | enum ip_conntrack_info ctinfo; | |
1080 | struct nf_conn *ct; | |
1081 | struct nf_conn_synproxy *synproxy; | |
1082 | struct synproxy_options opts = {}; | |
1083 | const struct ip_ct_tcp *state; | |
1084 | struct tcphdr *th, _th; | |
1085 | __be16 frag_off; | |
1086 | u8 nexthdr; | |
1087 | int thoff; | |
1088 | ||
1089 | ct = nf_ct_get(skb, &ctinfo); | |
1090 | if (!ct) | |
1091 | return NF_ACCEPT; | |
1092 | ||
1093 | synproxy = nfct_synproxy(ct); | |
1094 | if (!synproxy) | |
1095 | return NF_ACCEPT; | |
1096 | ||
1097 | if (nf_is_loopback_packet(skb)) | |
1098 | return NF_ACCEPT; | |
1099 | ||
1100 | nexthdr = ipv6_hdr(skb)->nexthdr; | |
1101 | thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, | |
1102 | &frag_off); | |
1103 | if (thoff < 0 || nexthdr != IPPROTO_TCP) | |
1104 | return NF_ACCEPT; | |
1105 | ||
1106 | th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); | |
1107 | if (!th) | |
1108 | return NF_DROP; | |
1109 | ||
1110 | state = &ct->proto.tcp; | |
1111 | switch (state->state) { | |
1112 | case TCP_CONNTRACK_CLOSE: | |
e971ceb8 | 1113 | if (th->rst && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) { |
d7f9b2f1 FFM |
1114 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - |
1115 | ntohl(th->seq) + 1); | |
1116 | break; | |
1117 | } | |
1118 | ||
1119 | if (!th->syn || th->ack || | |
1120 | CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
1121 | break; | |
1122 | ||
1123 | /* Reopened connection - reset the sequence number and timestamp | |
1124 | * adjustments, they will get initialized once the connection is | |
1125 | * reestablished. | |
1126 | */ | |
1127 | nf_ct_seqadj_init(ct, ctinfo, 0); | |
1128 | synproxy->tsoff = 0; | |
1129 | this_cpu_inc(snet->stats->conn_reopened); | |
954d8297 | 1130 | fallthrough; |
d7f9b2f1 FFM |
1131 | case TCP_CONNTRACK_SYN_SENT: |
1132 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
1133 | return NF_DROP; | |
1134 | ||
1135 | if (!th->syn && th->ack && | |
1136 | CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) { | |
1137 | /* Keep-Alives are sent with SEG.SEQ = SND.NXT-1, | |
1138 | * therefore we need to add 1 to make the SYN sequence | |
1139 | * number match the one of first SYN. | |
1140 | */ | |
1141 | if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts, | |
1142 | ntohl(th->seq) + 1)) { | |
1143 | this_cpu_inc(snet->stats->cookie_retrans); | |
1144 | consume_skb(skb); | |
1145 | return NF_STOLEN; | |
1146 | } else { | |
1147 | return NF_DROP; | |
1148 | } | |
1149 | } | |
1150 | ||
1151 | synproxy->isn = ntohl(th->ack_seq); | |
1152 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) | |
1153 | synproxy->its = opts.tsecr; | |
1154 | ||
1155 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
1156 | break; | |
1157 | case TCP_CONNTRACK_SYN_RECV: | |
1158 | if (!th->syn || !th->ack) | |
1159 | break; | |
1160 | ||
1161 | if (!synproxy_parse_options(skb, thoff, th, &opts)) | |
1162 | return NF_DROP; | |
1163 | ||
1164 | if (opts.options & NF_SYNPROXY_OPT_TIMESTAMP) { | |
1165 | synproxy->tsoff = opts.tsval - synproxy->its; | |
1166 | nf_conntrack_event_cache(IPCT_SYNPROXY, ct); | |
1167 | } | |
1168 | ||
1169 | opts.options &= ~(NF_SYNPROXY_OPT_MSS | | |
1170 | NF_SYNPROXY_OPT_WSCALE | | |
1171 | NF_SYNPROXY_OPT_SACK_PERM); | |
1172 | ||
1173 | swap(opts.tsval, opts.tsecr); | |
1174 | synproxy_send_server_ack_ipv6(net, state, skb, th, &opts); | |
1175 | ||
1176 | nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq)); | |
1177 | nf_conntrack_event_cache(IPCT_SEQADJ, ct); | |
1178 | ||
1179 | swap(opts.tsval, opts.tsecr); | |
1180 | synproxy_send_client_ack_ipv6(net, skb, th, &opts); | |
1181 | ||
1182 | consume_skb(skb); | |
1183 | return NF_STOLEN; | |
1184 | default: | |
1185 | break; | |
1186 | } | |
1187 | ||
1188 | synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy); | |
1189 | return NF_ACCEPT; | |
1190 | } | |
1191 | EXPORT_SYMBOL_GPL(ipv6_synproxy_hook); | |
1192 | ||
1193 | static const struct nf_hook_ops ipv6_synproxy_ops[] = { | |
1194 | { | |
1195 | .hook = ipv6_synproxy_hook, | |
1196 | .pf = NFPROTO_IPV6, | |
1197 | .hooknum = NF_INET_LOCAL_IN, | |
1198 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
1199 | }, | |
1200 | { | |
1201 | .hook = ipv6_synproxy_hook, | |
1202 | .pf = NFPROTO_IPV6, | |
1203 | .hooknum = NF_INET_POST_ROUTING, | |
1204 | .priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1, | |
1205 | }, | |
1206 | }; | |
1207 | ||
1208 | int | |
1209 | nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net) | |
1210 | { | |
1211 | int err; | |
1212 | ||
1213 | if (snet->hook_ref6 == 0) { | |
1214 | err = nf_register_net_hooks(net, ipv6_synproxy_ops, | |
1215 | ARRAY_SIZE(ipv6_synproxy_ops)); | |
1216 | if (err) | |
1217 | return err; | |
1218 | } | |
1219 | ||
1220 | snet->hook_ref6++; | |
72c5e118 | 1221 | return 0; |
d7f9b2f1 FFM |
1222 | } |
1223 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init); | |
1224 | ||
1225 | void | |
1226 | nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net) | |
1227 | { | |
1228 | snet->hook_ref6--; | |
1229 | if (snet->hook_ref6 == 0) | |
1230 | nf_unregister_net_hooks(net, ipv6_synproxy_ops, | |
1231 | ARRAY_SIZE(ipv6_synproxy_ops)); | |
1232 | } | |
1233 | EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini); | |
1234 | #endif /* CONFIG_IPV6 */ | |
1235 | ||
48b1de4c PM |
1236 | MODULE_LICENSE("GPL"); |
1237 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
4cacc395 | 1238 | MODULE_DESCRIPTION("nftables SYNPROXY expression support"); |