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>
15 #include <linux/netfilter_ipv4/ip_tables.h>
16 #include <linux/netfilter/x_tables.h>
17 #include <linux/netfilter/xt_tcpudp.h>
18 #include <linux/netfilter/xt_SYNPROXY.h>
19 #include <net/netfilter/nf_conntrack.h>
20 #include <net/netfilter/nf_conntrack_extend.h>
21 #include <net/netfilter/nf_conntrack_seqadj.h>
22 #include <net/netfilter/nf_conntrack_synproxy.h>
25 EXPORT_SYMBOL_GPL(synproxy_net_id);
28 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
29 const struct tcphdr *th, struct synproxy_options *opts)
31 int length = (th->doff * 4) - sizeof(*th);
34 ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
58 if (opsize == TCPOLEN_MSS) {
59 opts->mss = get_unaligned_be16(ptr);
60 opts->options |= XT_SYNPROXY_OPT_MSS;
64 if (opsize == TCPOLEN_WINDOW) {
66 if (opts->wscale > 14)
68 opts->options |= XT_SYNPROXY_OPT_WSCALE;
71 case TCPOPT_TIMESTAMP:
72 if (opsize == TCPOLEN_TIMESTAMP) {
73 opts->tsval = get_unaligned_be32(ptr);
74 opts->tsecr = get_unaligned_be32(ptr + 4);
75 opts->options |= XT_SYNPROXY_OPT_TIMESTAMP;
78 case TCPOPT_SACK_PERM:
79 if (opsize == TCPOLEN_SACK_PERM)
80 opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
90 EXPORT_SYMBOL_GPL(synproxy_parse_options);
92 unsigned int synproxy_options_size(const struct synproxy_options *opts)
94 unsigned int size = 0;
96 if (opts->options & XT_SYNPROXY_OPT_MSS)
97 size += TCPOLEN_MSS_ALIGNED;
98 if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
99 size += TCPOLEN_TSTAMP_ALIGNED;
100 else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
101 size += TCPOLEN_SACKPERM_ALIGNED;
102 if (opts->options & XT_SYNPROXY_OPT_WSCALE)
103 size += TCPOLEN_WSCALE_ALIGNED;
107 EXPORT_SYMBOL_GPL(synproxy_options_size);
110 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
112 __be32 *ptr = (__be32 *)(th + 1);
113 u8 options = opts->options;
115 if (options & XT_SYNPROXY_OPT_MSS)
116 *ptr++ = htonl((TCPOPT_MSS << 24) |
117 (TCPOLEN_MSS << 16) |
120 if (options & XT_SYNPROXY_OPT_TIMESTAMP) {
121 if (options & XT_SYNPROXY_OPT_SACK_PERM)
122 *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
123 (TCPOLEN_SACK_PERM << 16) |
124 (TCPOPT_TIMESTAMP << 8) |
127 *ptr++ = htonl((TCPOPT_NOP << 24) |
129 (TCPOPT_TIMESTAMP << 8) |
132 *ptr++ = htonl(opts->tsval);
133 *ptr++ = htonl(opts->tsecr);
134 } else if (options & XT_SYNPROXY_OPT_SACK_PERM)
135 *ptr++ = htonl((TCPOPT_NOP << 24) |
137 (TCPOPT_SACK_PERM << 8) |
140 if (options & XT_SYNPROXY_OPT_WSCALE)
141 *ptr++ = htonl((TCPOPT_NOP << 24) |
142 (TCPOPT_WINDOW << 16) |
143 (TCPOLEN_WINDOW << 8) |
146 EXPORT_SYMBOL_GPL(synproxy_build_options);
148 void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
149 struct synproxy_options *opts)
151 opts->tsecr = opts->tsval;
152 opts->tsval = tcp_time_stamp & ~0x3f;
154 if (opts->options & XT_SYNPROXY_OPT_WSCALE)
155 opts->tsval |= info->wscale;
159 if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
160 opts->tsval |= 1 << 4;
162 if (opts->options & XT_SYNPROXY_OPT_ECN)
163 opts->tsval |= 1 << 5;
165 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
167 void synproxy_check_timestamp_cookie(struct synproxy_options *opts)
169 opts->wscale = opts->tsecr & 0xf;
170 if (opts->wscale != 0xf)
171 opts->options |= XT_SYNPROXY_OPT_WSCALE;
173 opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
175 opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0;
177 EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie);
179 unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
180 unsigned int protoff,
183 enum ip_conntrack_info ctinfo,
184 const struct nf_conn_synproxy *synproxy)
186 unsigned int optoff, optend;
189 if (synproxy->tsoff == 0)
192 optoff = protoff + sizeof(struct tcphdr);
193 optend = protoff + th->doff * 4;
195 if (!skb_make_writable(skb, optend))
198 while (optoff < optend) {
199 unsigned char *op = skb->data + optoff;
208 if (optoff + 1 == optend ||
209 optoff + op[1] > optend ||
212 if (op[0] == TCPOPT_TIMESTAMP &&
213 op[1] == TCPOLEN_TIMESTAMP) {
214 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
217 *ptr = htonl(ntohl(*ptr) -
222 *ptr = htonl(ntohl(*ptr) +
225 inet_proto_csum_replace4(&th->check, skb,
234 EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust);
236 static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
237 .len = sizeof(struct nf_conn_synproxy),
238 .align = __alignof__(struct nf_conn_synproxy),
239 .id = NF_CT_EXT_SYNPROXY,
242 #ifdef CONFIG_PROC_FS
243 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
245 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
249 return SEQ_START_TOKEN;
251 for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
252 if (!cpu_possible(cpu))
255 return per_cpu_ptr(snet->stats, cpu);
261 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
263 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
266 for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
267 if (!cpu_possible(cpu))
270 return per_cpu_ptr(snet->stats, cpu);
276 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
281 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
283 struct synproxy_stats *stats = v;
285 if (v == SEQ_START_TOKEN) {
286 seq_printf(seq, "entries\t\tsyn_received\t"
287 "cookie_invalid\tcookie_valid\t"
288 "cookie_retrans\tconn_reopened\n");
292 seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
294 stats->cookie_invalid,
296 stats->cookie_retrans,
297 stats->conn_reopened);
302 static const struct seq_operations synproxy_cpu_seq_ops = {
303 .start = synproxy_cpu_seq_start,
304 .next = synproxy_cpu_seq_next,
305 .stop = synproxy_cpu_seq_stop,
306 .show = synproxy_cpu_seq_show,
309 static int synproxy_cpu_seq_open(struct inode *inode, struct file *file)
311 return seq_open_net(inode, file, &synproxy_cpu_seq_ops,
312 sizeof(struct seq_net_private));
315 static const struct file_operations synproxy_cpu_seq_fops = {
316 .owner = THIS_MODULE,
317 .open = synproxy_cpu_seq_open,
320 .release = seq_release_net,
323 static int __net_init synproxy_proc_init(struct net *net)
325 if (!proc_create("synproxy", S_IRUGO, net->proc_net_stat,
326 &synproxy_cpu_seq_fops))
331 static void __net_exit synproxy_proc_exit(struct net *net)
333 remove_proc_entry("synproxy", net->proc_net_stat);
336 static int __net_init synproxy_proc_init(struct net *net)
341 static void __net_exit synproxy_proc_exit(struct net *net)
345 #endif /* CONFIG_PROC_FS */
347 static int __net_init synproxy_net_init(struct net *net)
349 struct synproxy_net *snet = synproxy_pernet(net);
350 struct nf_conntrack_tuple t;
354 memset(&t, 0, sizeof(t));
355 ct = nf_conntrack_alloc(net, 0, &t, &t, GFP_KERNEL);
361 if (!nfct_seqadj_ext_add(ct))
363 if (!nfct_synproxy_ext_add(ct))
365 __set_bit(IPS_TEMPLATE_BIT, &ct->status);
366 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
370 snet->stats = alloc_percpu(struct synproxy_stats);
371 if (snet->stats == NULL)
374 err = synproxy_proc_init(net);
381 free_percpu(snet->stats);
383 nf_conntrack_free(ct);
388 static void __net_exit synproxy_net_exit(struct net *net)
390 struct synproxy_net *snet = synproxy_pernet(net);
392 nf_conntrack_free(snet->tmpl);
393 synproxy_proc_exit(net);
394 free_percpu(snet->stats);
397 static struct pernet_operations synproxy_net_ops = {
398 .init = synproxy_net_init,
399 .exit = synproxy_net_exit,
400 .id = &synproxy_net_id,
401 .size = sizeof(struct synproxy_net),
404 static int __init synproxy_core_init(void)
408 err = nf_ct_extend_register(&nf_ct_synproxy_extend);
412 err = register_pernet_subsys(&synproxy_net_ops);
419 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
424 static void __exit synproxy_core_exit(void)
426 unregister_pernet_subsys(&synproxy_net_ops);
427 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
430 module_init(synproxy_core_init);
431 module_exit(synproxy_core_exit);
433 MODULE_LICENSE("GPL");
434 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");