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blkcg: misc preparations for unified hierarchy interface
[linux-2.6/btrfs-unstable.git] / net / netfilter / nf_synproxy_core.c
blob789feeae6c44a82b44e040ae2a6bec6f26cbe450
1 /*
2 * Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
3 *
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.
7 */
8
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <asm/unaligned.h>
12 #include <net/tcp.h>
13 #include <net/netns/generic.h>
14 #include <linux/proc_fs.h>
15
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>
24
25 int synproxy_net_id;
26 EXPORT_SYMBOL_GPL(synproxy_net_id);
27
28 bool
29 synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
30 const struct tcphdr *th, struct synproxy_options *opts)
31 {
32 int length = (th->doff * 4) - sizeof(*th);
33 u8 buf[40], *ptr;
34
35 ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
36 if (ptr == NULL)
37 return false;
38
39 opts->options = 0;
40 while (length > 0) {
41 int opcode = *ptr++;
42 int opsize;
43
44 switch (opcode) {
45 case TCPOPT_EOL:
46 return true;
47 case TCPOPT_NOP:
48 length--;
49 continue;
50 default:
51 opsize = *ptr++;
52 if (opsize < 2)
53 return true;
54 if (opsize > length)
55 return true;
56
57 switch (opcode) {
58 case TCPOPT_MSS:
59 if (opsize == TCPOLEN_MSS) {
60 opts->mss = get_unaligned_be16(ptr);
61 opts->options |= XT_SYNPROXY_OPT_MSS;
62 }
63 break;
64 case TCPOPT_WINDOW:
65 if (opsize == TCPOLEN_WINDOW) {
66 opts->wscale = *ptr;
67 if (opts->wscale > 14)
68 opts->wscale = 14;
69 opts->options |= XT_SYNPROXY_OPT_WSCALE;
70 }
71 break;
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;
77 }
78 break;
79 case TCPOPT_SACK_PERM:
80 if (opsize == TCPOLEN_SACK_PERM)
81 opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
82 break;
83 }
84
85 ptr += opsize - 2;
86 length -= opsize;
87 }
88 }
89 return true;
90 }
91 EXPORT_SYMBOL_GPL(synproxy_parse_options);
92
93 unsigned int synproxy_options_size(const struct synproxy_options *opts)
94 {
95 unsigned int size = 0;
96
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;
105
106 return size;
107 }
108 EXPORT_SYMBOL_GPL(synproxy_options_size);
109
110 void
111 synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
112 {
113 __be32 *ptr = (__be32 *)(th + 1);
114 u8 options = opts->options;
115
116 if (options & XT_SYNPROXY_OPT_MSS)
117 *ptr++ = htonl((TCPOPT_MSS << 24) |
118 (TCPOLEN_MSS << 16) |
119 opts->mss);
120
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) |
126 TCPOLEN_TIMESTAMP);
127 else
128 *ptr++ = htonl((TCPOPT_NOP << 24) |
129 (TCPOPT_NOP << 16) |
130 (TCPOPT_TIMESTAMP << 8) |
131 TCPOLEN_TIMESTAMP);
132
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) |
137 (TCPOPT_NOP << 16) |
138 (TCPOPT_SACK_PERM << 8) |
139 TCPOLEN_SACK_PERM);
140
141 if (options & XT_SYNPROXY_OPT_WSCALE)
142 *ptr++ = htonl((TCPOPT_NOP << 24) |
143 (TCPOPT_WINDOW << 16) |
144 (TCPOLEN_WINDOW << 8) |
145 opts->wscale);
146 }
147 EXPORT_SYMBOL_GPL(synproxy_build_options);
148
149 void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
150 struct synproxy_options *opts)
151 {
152 opts->tsecr = opts->tsval;
153 opts->tsval = tcp_time_stamp & ~0x3f;
154
155 if (opts->options & XT_SYNPROXY_OPT_WSCALE) {
156 opts->tsval |= opts->wscale;
157 opts->wscale = info->wscale;
158 } else
159 opts->tsval |= 0xf;
160
161 if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
162 opts->tsval |= 1 << 4;
163
164 if (opts->options & XT_SYNPROXY_OPT_ECN)
165 opts->tsval |= 1 << 5;
166 }
167 EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
168
169 void synproxy_check_timestamp_cookie(struct synproxy_options *opts)
170 {
171 opts->wscale = opts->tsecr & 0xf;
172 if (opts->wscale != 0xf)
173 opts->options |= XT_SYNPROXY_OPT_WSCALE;
174
175 opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
176
177 opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0;
178 }
179 EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie);
180
181 unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
182 unsigned int protoff,
183 struct tcphdr *th,
184 struct nf_conn *ct,
185 enum ip_conntrack_info ctinfo,
186 const struct nf_conn_synproxy *synproxy)
187 {
188 unsigned int optoff, optend;
189 u32 *ptr, old;
190
191 if (synproxy->tsoff == 0)
192 return 1;
193
194 optoff = protoff + sizeof(struct tcphdr);
195 optend = protoff + th->doff * 4;
196
197 if (!skb_make_writable(skb, optend))
198 return 0;
199
200 while (optoff < optend) {
201 unsigned char *op = skb->data + optoff;
202
203 switch (op[0]) {
204 case TCPOPT_EOL:
205 return 1;
206 case TCPOPT_NOP:
207 optoff++;
208 continue;
209 default:
210 if (optoff + 1 == optend ||
211 optoff + op[1] > optend ||
212 op[1] < 2)
213 return 0;
214 if (op[0] == TCPOPT_TIMESTAMP &&
215 op[1] == TCPOLEN_TIMESTAMP) {
216 if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
217 ptr = (u32 *)&op[2];
218 old = *ptr;
219 *ptr = htonl(ntohl(*ptr) -
220 synproxy->tsoff);
221 } else {
222 ptr = (u32 *)&op[6];
223 old = *ptr;
224 *ptr = htonl(ntohl(*ptr) +
225 synproxy->tsoff);
226 }
227 inet_proto_csum_replace4(&th->check, skb,
228 old, *ptr, 0);
229 return 1;
230 }
231 optoff += op[1];
232 }
233 }
234 return 1;
235 }
236 EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust);
237
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,
242 };
243
244 #ifdef CONFIG_PROC_FS
245 static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
246 {
247 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
248 int cpu;
249
250 if (*pos == 0)
251 return SEQ_START_TOKEN;
252
253 for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
254 if (!cpu_possible(cpu))
255 continue;
256 *pos = cpu + 1;
257 return per_cpu_ptr(snet->stats, cpu);
258 }
259
260 return NULL;
261 }
262
263 static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
264 {
265 struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
266 int cpu;
267
268 for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
269 if (!cpu_possible(cpu))
270 continue;
271 *pos = cpu + 1;
272 return per_cpu_ptr(snet->stats, cpu);
273 }
274
275 return NULL;
276 }
277
278 static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
279 {
280 return;
281 }
282
283 static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
284 {
285 struct synproxy_stats *stats = v;
286
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");
291 return 0;
292 }
293
294 seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
295 stats->syn_received,
296 stats->cookie_invalid,
297 stats->cookie_valid,
298 stats->cookie_retrans,
299 stats->conn_reopened);
300
301 return 0;
302 }
303
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,
309 };
310
311 static int synproxy_cpu_seq_open(struct inode *inode, struct file *file)
312 {
313 return seq_open_net(inode, file, &synproxy_cpu_seq_ops,
314 sizeof(struct seq_net_private));
315 }
316
317 static const struct file_operations synproxy_cpu_seq_fops = {
318 .owner = THIS_MODULE,
319 .open = synproxy_cpu_seq_open,
320 .read = seq_read,
321 .llseek = seq_lseek,
322 .release = seq_release_net,
323 };
324
325 static int __net_init synproxy_proc_init(struct net *net)
326 {
327 if (!proc_create("synproxy", S_IRUGO, net->proc_net_stat,
328 &synproxy_cpu_seq_fops))
329 return -ENOMEM;
330 return 0;
331 }
332
333 static void __net_exit synproxy_proc_exit(struct net *net)
334 {
335 remove_proc_entry("synproxy", net->proc_net_stat);
336 }
337 #else
338 static int __net_init synproxy_proc_init(struct net *net)
339 {
340 return 0;
341 }
342
343 static void __net_exit synproxy_proc_exit(struct net *net)
344 {
345 return;
346 }
347 #endif /* CONFIG_PROC_FS */
348
349 static int __net_init synproxy_net_init(struct net *net)
350 {
351 struct synproxy_net *snet = synproxy_pernet(net);
352 struct nf_conntrack_tuple t;
353 struct nf_conn *ct;
354 int err = -ENOMEM;
355
356 memset(&t, 0, sizeof(t));
357 ct = nf_conntrack_alloc(net, 0, &t, &t, GFP_KERNEL);
358 if (IS_ERR(ct)) {
359 err = PTR_ERR(ct);
360 goto err1;
361 }
362
363 if (!nfct_seqadj_ext_add(ct))
364 goto err2;
365 if (!nfct_synproxy_ext_add(ct))
366 goto err2;
367
368 nf_conntrack_tmpl_insert(net, ct);
369 snet->tmpl = ct;
370
371 snet->stats = alloc_percpu(struct synproxy_stats);
372 if (snet->stats == NULL)
373 goto err2;
374
375 err = synproxy_proc_init(net);
376 if (err < 0)
377 goto err3;
378
379 return 0;
380
381 err3:
382 free_percpu(snet->stats);
383 err2:
384 nf_conntrack_free(ct);
385 err1:
386 return err;
387 }
388
389 static void __net_exit synproxy_net_exit(struct net *net)
390 {
391 struct synproxy_net *snet = synproxy_pernet(net);
392
393 nf_ct_put(snet->tmpl);
394 synproxy_proc_exit(net);
395 free_percpu(snet->stats);
396 }
397
398 static struct pernet_operations synproxy_net_ops = {
399 .init = synproxy_net_init,
400 .exit = synproxy_net_exit,
401 .id = &synproxy_net_id,
402 .size = sizeof(struct synproxy_net),
403 };
404
405 static int __init synproxy_core_init(void)
406 {
407 int err;
408
409 err = nf_ct_extend_register(&nf_ct_synproxy_extend);
410 if (err < 0)
411 goto err1;
412
413 err = register_pernet_subsys(&synproxy_net_ops);
414 if (err < 0)
415 goto err2;
416
417 return 0;
418
419 err2:
420 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
421 err1:
422 return err;
423 }
424
425 static void __exit synproxy_core_exit(void)
426 {
427 unregister_pernet_subsys(&synproxy_net_ops);
428 nf_ct_extend_unregister(&nf_ct_synproxy_extend);
429 }
430
431 module_init(synproxy_core_init);
432 module_exit(synproxy_core_exit);
433
434 MODULE_LICENSE("GPL");
435 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
(deprecated) Btrfs devel tree