2 * Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <asm/unaligned.h>
13 #include <net/netns/generic.h>
14 #include <linux/proc_fs.h>
16 #include <linux/netfilter_ipv4/ip_tables.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_tcpudp.h>
19 #include <linux/netfilter/xt_SYNPROXY.h>
20 #include <net/netfilter/nf_conntrack.h>
21 #include <net/netfilter/nf_conntrack_extend.h>
22 #include <net/netfilter/nf_conntrack_seqadj.h>
23 #include <net/netfilter/nf_conntrack_synproxy.h>
26 EXPORT_SYMBOL_GPL(synproxy_net_id);
29 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
30 const struct tcphdr *th, struct synproxy_options *opts)
32 int length = (th->doff * 4) - sizeof(*th);
35 ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
59 if (opsize == TCPOLEN_MSS) {
60 opts->mss = get_unaligned_be16(ptr);
61 opts->options |= XT_SYNPROXY_OPT_MSS;
65 if (opsize == TCPOLEN_WINDOW) {
67 if (opts->wscale > 14)
69 opts->options |= XT_SYNPROXY_OPT_WSCALE;
72 case TCPOPT_TIMESTAMP:
73 if (opsize == TCPOLEN_TIMESTAMP) {
74 opts->tsval = get_unaligned_be32(ptr);
75 opts->tsecr = get_unaligned_be32(ptr + 4);
76 opts->options |= XT_SYNPROXY_OPT_TIMESTAMP;
79 case TCPOPT_SACK_PERM:
80 if (opsize == TCPOLEN_SACK_PERM)
81 opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
91 EXPORT_SYMBOL_GPL(synproxy_parse_options);
93 unsigned int synproxy_options_size(const struct synproxy_options *opts)
95 unsigned int size = 0;
97 if (opts->options & XT_SYNPROXY_OPT_MSS)
98 size += TCPOLEN_MSS_ALIGNED;
99 if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
100 size += TCPOLEN_TSTAMP_ALIGNED;
101 else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
102 size += TCPOLEN_SACKPERM_ALIGNED;
103 if (opts->options & XT_SYNPROXY_OPT_WSCALE)
104 size += TCPOLEN_WSCALE_ALIGNED;
108 EXPORT_SYMBOL_GPL(synproxy_options_size);
111 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
113 __be32 *ptr = (__be32 *)(th + 1);
114 u8 options = opts->options;
116 if (options & XT_SYNPROXY_OPT_MSS)
117 *ptr++ = htonl((TCPOPT_MSS << 24) |
118 (TCPOLEN_MSS << 16) |
121 if (options & XT_SYNPROXY_OPT_TIMESTAMP) {
122 if (options & XT_SYNPROXY_OPT_SACK_PERM)
123 *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
124 (TCPOLEN_SACK_PERM << 16) |
125 (TCPOPT_TIMESTAMP << 8) |
128 *ptr++ = htonl((TCPOPT_NOP << 24) |
130 (TCPOPT_TIMESTAMP << 8) |
133 *ptr++ = htonl(opts->tsval);
134 *ptr++ = htonl(opts->tsecr);
135 } else if (options & XT_SYNPROXY_OPT_SACK_PERM)
136 *ptr++ = htonl((TCPOPT_NOP << 24) |
138 (TCPOPT_SACK_PERM << 8) |
141 if (options & XT_SYNPROXY_OPT_WSCALE)
142 *ptr++ = htonl((TCPOPT_NOP << 24) |
143 (TCPOPT_WINDOW << 16) |
144 (TCPOLEN_WINDOW << 8) |
147 EXPORT_SYMBOL_GPL(synproxy_build_options);
149 void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
150 struct synproxy_options *opts)
152 opts->tsecr = opts->tsval;
153 opts->tsval = tcp_time_stamp & ~0x3f;
155 if (opts->options & XT_SYNPROXY_OPT_WSCALE) {
156 opts->tsval |= opts->wscale;
157 opts->wscale = info->wscale;
161 if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
162 opts->tsval |= 1 << 4;
164 if (opts->options & XT_SYNPROXY_OPT_ECN)
165 opts->tsval |= 1 << 5;
167 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
169 void synproxy_check_timestamp_cookie(struct synproxy_options *opts)
171 opts->wscale = opts->tsecr & 0xf;
172 if (opts->wscale != 0xf)
173 opts->options |= XT_SYNPROXY_OPT_WSCALE;
175 opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
177 opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0;
179 EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie);
181 unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
182 unsigned int protoff,
185 enum ip_conntrack_info ctinfo,
186 const struct nf_conn_synproxy *synproxy)
188 unsigned int optoff, optend;
191 if (synproxy->tsoff == 0)
194 optoff = protoff + sizeof(struct tcphdr);
195 optend = protoff + th->doff * 4;
197 if (!skb_make_writable(skb, optend))
200 while (optoff < optend) {
201 unsigned char *op = skb->data + optoff;
210 if (optoff + 1 == optend ||
211 optoff + op[1] > optend ||
214 if (op[0] == TCPOPT_TIMESTAMP &&
215 op[1] == TCPOLEN_TIMESTAMP) {
216 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
219 *ptr = htonl(ntohl(*ptr) -
224 *ptr = htonl(ntohl(*ptr) +
227 inet_proto_csum_replace4(&th->check, skb,
236 EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust);
238 static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
239 .len = sizeof(struct nf_conn_synproxy),
240 .align = __alignof__(struct nf_conn_synproxy),
241 .id = NF_CT_EXT_SYNPROXY,
244 #ifdef CONFIG_PROC_FS
245 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
247 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
251 return SEQ_START_TOKEN;
253 for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
254 if (!cpu_possible(cpu))
257 return per_cpu_ptr(snet->stats, cpu);
263 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
265 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
268 for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
269 if (!cpu_possible(cpu))
272 return per_cpu_ptr(snet->stats, cpu);
278 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
283 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
285 struct synproxy_stats *stats = v;
287 if (v == SEQ_START_TOKEN) {
288 seq_printf(seq, "entries\t\tsyn_received\t"
289 "cookie_invalid\tcookie_valid\t"
290 "cookie_retrans\tconn_reopened\n");
294 seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
296 stats->cookie_invalid,
298 stats->cookie_retrans,
299 stats->conn_reopened);
304 static const struct seq_operations synproxy_cpu_seq_ops = {
305 .start = synproxy_cpu_seq_start,
306 .next = synproxy_cpu_seq_next,
307 .stop = synproxy_cpu_seq_stop,
308 .show = synproxy_cpu_seq_show,
311 static int synproxy_cpu_seq_open(struct inode *inode, struct file *file)
313 return seq_open_net(inode, file, &synproxy_cpu_seq_ops,
314 sizeof(struct seq_net_private));
317 static const struct file_operations synproxy_cpu_seq_fops = {
318 .owner = THIS_MODULE,
319 .open = synproxy_cpu_seq_open,
322 .release = seq_release_net,
325 static int __net_init synproxy_proc_init(struct net *net)
327 if (!proc_create("synproxy", S_IRUGO, net->proc_net_stat,
328 &synproxy_cpu_seq_fops))
333 static void __net_exit synproxy_proc_exit(struct net *net)
335 remove_proc_entry("synproxy", net->proc_net_stat);
338 static int __net_init synproxy_proc_init(struct net *net)
343 static void __net_exit synproxy_proc_exit(struct net *net)
347 #endif /* CONFIG_PROC_FS */
349 static int __net_init synproxy_net_init(struct net *net)
351 struct synproxy_net *snet = synproxy_pernet(net);
355 ct = nf_ct_tmpl_alloc(net, 0, GFP_KERNEL);
359 if (!nfct_seqadj_ext_add(ct))
361 if (!nfct_synproxy_ext_add(ct))
364 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
365 nf_conntrack_get(&ct->ct_general);
368 snet->stats = alloc_percpu(struct synproxy_stats);
369 if (snet->stats == NULL)
372 err = synproxy_proc_init(net);
379 free_percpu(snet->stats);
381 nf_conntrack_free(ct);
386 static void __net_exit synproxy_net_exit(struct net *net)
388 struct synproxy_net *snet = synproxy_pernet(net);
390 nf_ct_put(snet->tmpl);
391 synproxy_proc_exit(net);
392 free_percpu(snet->stats);
395 static struct pernet_operations synproxy_net_ops = {
396 .init = synproxy_net_init,
397 .exit = synproxy_net_exit,
398 .id = &synproxy_net_id,
399 .size = sizeof(struct synproxy_net),
402 static int __init synproxy_core_init(void)
406 err = nf_ct_extend_register(&nf_ct_synproxy_extend);
410 err = register_pernet_subsys(&synproxy_net_ops);
417 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
422 static void __exit synproxy_core_exit(void)
424 unregister_pernet_subsys(&synproxy_net_ops);
425 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
428 module_init(synproxy_core_init);
429 module_exit(synproxy_core_exit);
431 MODULE_LICENSE("GPL");
432 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");