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>
21 #include <net/netfilter/nf_conntrack.h>
22 #include <net/netfilter/nf_conntrack_extend.h>
23 #include <net/netfilter/nf_conntrack_seqadj.h>
24 #include <net/netfilter/nf_conntrack_synproxy.h>
25 #include <net/netfilter/nf_conntrack_zones.h>
27 unsigned int synproxy_net_id;
28 EXPORT_SYMBOL_GPL(synproxy_net_id);
31 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
32 const struct tcphdr *th, struct synproxy_options *opts)
34 int length = (th->doff * 4) - sizeof(*th);
37 ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
61 if (opsize == TCPOLEN_MSS) {
62 opts->mss = get_unaligned_be16(ptr);
63 opts->options |= XT_SYNPROXY_OPT_MSS;
67 if (opsize == TCPOLEN_WINDOW) {
69 if (opts->wscale > TCP_MAX_WSCALE)
70 opts->wscale = TCP_MAX_WSCALE;
71 opts->options |= XT_SYNPROXY_OPT_WSCALE;
74 case TCPOPT_TIMESTAMP:
75 if (opsize == TCPOLEN_TIMESTAMP) {
76 opts->tsval = get_unaligned_be32(ptr);
77 opts->tsecr = get_unaligned_be32(ptr + 4);
78 opts->options |= XT_SYNPROXY_OPT_TIMESTAMP;
81 case TCPOPT_SACK_PERM:
82 if (opsize == TCPOLEN_SACK_PERM)
83 opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
93 EXPORT_SYMBOL_GPL(synproxy_parse_options);
95 unsigned int synproxy_options_size(const struct synproxy_options *opts)
97 unsigned int size = 0;
99 if (opts->options & XT_SYNPROXY_OPT_MSS)
100 size += TCPOLEN_MSS_ALIGNED;
101 if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
102 size += TCPOLEN_TSTAMP_ALIGNED;
103 else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
104 size += TCPOLEN_SACKPERM_ALIGNED;
105 if (opts->options & XT_SYNPROXY_OPT_WSCALE)
106 size += TCPOLEN_WSCALE_ALIGNED;
110 EXPORT_SYMBOL_GPL(synproxy_options_size);
113 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
115 __be32 *ptr = (__be32 *)(th + 1);
116 u8 options = opts->options;
118 if (options & XT_SYNPROXY_OPT_MSS)
119 *ptr++ = htonl((TCPOPT_MSS << 24) |
120 (TCPOLEN_MSS << 16) |
123 if (options & XT_SYNPROXY_OPT_TIMESTAMP) {
124 if (options & XT_SYNPROXY_OPT_SACK_PERM)
125 *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
126 (TCPOLEN_SACK_PERM << 16) |
127 (TCPOPT_TIMESTAMP << 8) |
130 *ptr++ = htonl((TCPOPT_NOP << 24) |
132 (TCPOPT_TIMESTAMP << 8) |
135 *ptr++ = htonl(opts->tsval);
136 *ptr++ = htonl(opts->tsecr);
137 } else if (options & XT_SYNPROXY_OPT_SACK_PERM)
138 *ptr++ = htonl((TCPOPT_NOP << 24) |
140 (TCPOPT_SACK_PERM << 8) |
143 if (options & XT_SYNPROXY_OPT_WSCALE)
144 *ptr++ = htonl((TCPOPT_NOP << 24) |
145 (TCPOPT_WINDOW << 16) |
146 (TCPOLEN_WINDOW << 8) |
149 EXPORT_SYMBOL_GPL(synproxy_build_options);
151 void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
152 struct synproxy_options *opts)
154 opts->tsecr = opts->tsval;
155 opts->tsval = tcp_time_stamp_raw() & ~0x3f;
157 if (opts->options & XT_SYNPROXY_OPT_WSCALE) {
158 opts->tsval |= opts->wscale;
159 opts->wscale = info->wscale;
163 if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
164 opts->tsval |= 1 << 4;
166 if (opts->options & XT_SYNPROXY_OPT_ECN)
167 opts->tsval |= 1 << 5;
169 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
171 void synproxy_check_timestamp_cookie(struct synproxy_options *opts)
173 opts->wscale = opts->tsecr & 0xf;
174 if (opts->wscale != 0xf)
175 opts->options |= XT_SYNPROXY_OPT_WSCALE;
177 opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
179 opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0;
181 EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie);
183 unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
184 unsigned int protoff,
187 enum ip_conntrack_info ctinfo,
188 const struct nf_conn_synproxy *synproxy)
190 unsigned int optoff, optend;
193 if (synproxy->tsoff == 0)
196 optoff = protoff + sizeof(struct tcphdr);
197 optend = protoff + th->doff * 4;
199 if (!skb_make_writable(skb, optend))
202 while (optoff < optend) {
203 unsigned char *op = skb->data + optoff;
212 if (optoff + 1 == optend ||
213 optoff + op[1] > optend ||
216 if (op[0] == TCPOPT_TIMESTAMP &&
217 op[1] == TCPOLEN_TIMESTAMP) {
218 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
219 ptr = (__be32 *)&op[2];
221 *ptr = htonl(ntohl(*ptr) -
224 ptr = (__be32 *)&op[6];
226 *ptr = htonl(ntohl(*ptr) +
229 inet_proto_csum_replace4(&th->check, skb,
238 EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust);
240 static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
241 .len = sizeof(struct nf_conn_synproxy),
242 .align = __alignof__(struct nf_conn_synproxy),
243 .id = NF_CT_EXT_SYNPROXY,
246 #ifdef CONFIG_PROC_FS
247 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
249 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
253 return SEQ_START_TOKEN;
255 for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
256 if (!cpu_possible(cpu))
259 return per_cpu_ptr(snet->stats, cpu);
265 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
267 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
270 for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
271 if (!cpu_possible(cpu))
274 return per_cpu_ptr(snet->stats, cpu);
280 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
285 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
287 struct synproxy_stats *stats = v;
289 if (v == SEQ_START_TOKEN) {
290 seq_puts(seq, "entries\t\tsyn_received\t"
291 "cookie_invalid\tcookie_valid\t"
292 "cookie_retrans\tconn_reopened\n");
296 seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
298 stats->cookie_invalid,
300 stats->cookie_retrans,
301 stats->conn_reopened);
306 static const struct seq_operations synproxy_cpu_seq_ops = {
307 .start = synproxy_cpu_seq_start,
308 .next = synproxy_cpu_seq_next,
309 .stop = synproxy_cpu_seq_stop,
310 .show = synproxy_cpu_seq_show,
313 static int __net_init synproxy_proc_init(struct net *net)
315 if (!proc_create_net("synproxy", 0444, net->proc_net_stat,
316 &synproxy_cpu_seq_ops, sizeof(struct seq_net_private)))
321 static void __net_exit synproxy_proc_exit(struct net *net)
323 remove_proc_entry("synproxy", net->proc_net_stat);
326 static int __net_init synproxy_proc_init(struct net *net)
331 static void __net_exit synproxy_proc_exit(struct net *net)
335 #endif /* CONFIG_PROC_FS */
337 static int __net_init synproxy_net_init(struct net *net)
339 struct synproxy_net *snet = synproxy_pernet(net);
343 ct = nf_ct_tmpl_alloc(net, &nf_ct_zone_dflt, GFP_KERNEL);
347 if (!nfct_seqadj_ext_add(ct))
349 if (!nfct_synproxy_ext_add(ct))
352 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
353 nf_conntrack_get(&ct->ct_general);
356 snet->stats = alloc_percpu(struct synproxy_stats);
357 if (snet->stats == NULL)
360 err = synproxy_proc_init(net);
367 free_percpu(snet->stats);
374 static void __net_exit synproxy_net_exit(struct net *net)
376 struct synproxy_net *snet = synproxy_pernet(net);
378 nf_ct_put(snet->tmpl);
379 synproxy_proc_exit(net);
380 free_percpu(snet->stats);
383 static struct pernet_operations synproxy_net_ops = {
384 .init = synproxy_net_init,
385 .exit = synproxy_net_exit,
386 .id = &synproxy_net_id,
387 .size = sizeof(struct synproxy_net),
390 static int __init synproxy_core_init(void)
394 err = nf_ct_extend_register(&nf_ct_synproxy_extend);
398 err = register_pernet_subsys(&synproxy_net_ops);
405 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
410 static void __exit synproxy_core_exit(void)
412 unregister_pernet_subsys(&synproxy_net_ops);
413 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
416 module_init(synproxy_core_init);
417 module_exit(synproxy_core_exit);
419 MODULE_LICENSE("GPL");
420 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");