Commit | Line | Data |
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77ab9cff MJ |
1 | /* Expectation handling for nf_conntrack. */ |
2 | ||
3 | /* (C) 1999-2001 Paul `Rusty' Russell | |
4 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
5 | * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #include <linux/types.h> | |
13 | #include <linux/netfilter.h> | |
14 | #include <linux/skbuff.h> | |
15 | #include <linux/proc_fs.h> | |
16 | #include <linux/seq_file.h> | |
17 | #include <linux/stddef.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/err.h> | |
20 | #include <linux/percpu.h> | |
21 | #include <linux/kernel.h> | |
22 | ||
23 | #include <net/netfilter/nf_conntrack.h> | |
24 | #include <net/netfilter/nf_conntrack_core.h> | |
25 | #include <net/netfilter/nf_conntrack_expect.h> | |
26 | #include <net/netfilter/nf_conntrack_helper.h> | |
27 | #include <net/netfilter/nf_conntrack_tuple.h> | |
28 | ||
29 | LIST_HEAD(nf_conntrack_expect_list); | |
30 | kmem_cache_t *nf_conntrack_expect_cachep __read_mostly; | |
77ab9cff MJ |
31 | static unsigned int nf_conntrack_expect_next_id; |
32 | ||
33 | /* nf_conntrack_expect helper functions */ | |
34 | void nf_ct_unlink_expect(struct nf_conntrack_expect *exp) | |
35 | { | |
36 | struct nf_conn_help *master_help = nfct_help(exp->master); | |
37 | ||
38 | NF_CT_ASSERT(master_help); | |
39 | NF_CT_ASSERT(!timer_pending(&exp->timeout)); | |
40 | ||
41 | list_del(&exp->list); | |
42 | NF_CT_STAT_INC(expect_delete); | |
43 | master_help->expecting--; | |
44 | nf_conntrack_expect_put(exp); | |
45 | } | |
46 | ||
47 | static void expectation_timed_out(unsigned long ul_expect) | |
48 | { | |
49 | struct nf_conntrack_expect *exp = (void *)ul_expect; | |
50 | ||
51 | write_lock_bh(&nf_conntrack_lock); | |
52 | nf_ct_unlink_expect(exp); | |
53 | write_unlock_bh(&nf_conntrack_lock); | |
54 | nf_conntrack_expect_put(exp); | |
55 | } | |
56 | ||
57 | struct nf_conntrack_expect * | |
58 | __nf_conntrack_expect_find(const struct nf_conntrack_tuple *tuple) | |
59 | { | |
60 | struct nf_conntrack_expect *i; | |
61 | ||
62 | list_for_each_entry(i, &nf_conntrack_expect_list, list) { | |
63 | if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) | |
64 | return i; | |
65 | } | |
66 | return NULL; | |
67 | } | |
68 | ||
69 | /* Just find a expectation corresponding to a tuple. */ | |
70 | struct nf_conntrack_expect * | |
468ec44b | 71 | nf_conntrack_expect_find_get(const struct nf_conntrack_tuple *tuple) |
77ab9cff MJ |
72 | { |
73 | struct nf_conntrack_expect *i; | |
74 | ||
75 | read_lock_bh(&nf_conntrack_lock); | |
76 | i = __nf_conntrack_expect_find(tuple); | |
77 | if (i) | |
78 | atomic_inc(&i->use); | |
79 | read_unlock_bh(&nf_conntrack_lock); | |
80 | ||
81 | return i; | |
82 | } | |
83 | ||
84 | /* If an expectation for this connection is found, it gets delete from | |
85 | * global list then returned. */ | |
86 | struct nf_conntrack_expect * | |
87 | find_expectation(const struct nf_conntrack_tuple *tuple) | |
88 | { | |
89 | struct nf_conntrack_expect *i; | |
90 | ||
91 | list_for_each_entry(i, &nf_conntrack_expect_list, list) { | |
92 | /* If master is not in hash table yet (ie. packet hasn't left | |
93 | this machine yet), how can other end know about expected? | |
94 | Hence these are not the droids you are looking for (if | |
95 | master ct never got confirmed, we'd hold a reference to it | |
96 | and weird things would happen to future packets). */ | |
97 | if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask) | |
98 | && nf_ct_is_confirmed(i->master)) { | |
99 | if (i->flags & NF_CT_EXPECT_PERMANENT) { | |
100 | atomic_inc(&i->use); | |
101 | return i; | |
102 | } else if (del_timer(&i->timeout)) { | |
103 | nf_ct_unlink_expect(i); | |
104 | return i; | |
105 | } | |
106 | } | |
107 | } | |
108 | return NULL; | |
109 | } | |
110 | ||
111 | /* delete all expectations for this conntrack */ | |
112 | void nf_ct_remove_expectations(struct nf_conn *ct) | |
113 | { | |
114 | struct nf_conntrack_expect *i, *tmp; | |
115 | struct nf_conn_help *help = nfct_help(ct); | |
116 | ||
117 | /* Optimization: most connection never expect any others. */ | |
118 | if (!help || help->expecting == 0) | |
119 | return; | |
120 | ||
121 | list_for_each_entry_safe(i, tmp, &nf_conntrack_expect_list, list) { | |
122 | if (i->master == ct && del_timer(&i->timeout)) { | |
123 | nf_ct_unlink_expect(i); | |
124 | nf_conntrack_expect_put(i); | |
125 | } | |
126 | } | |
127 | } | |
128 | ||
129 | /* Would two expected things clash? */ | |
130 | static inline int expect_clash(const struct nf_conntrack_expect *a, | |
131 | const struct nf_conntrack_expect *b) | |
132 | { | |
133 | /* Part covered by intersection of masks must be unequal, | |
134 | otherwise they clash */ | |
135 | struct nf_conntrack_tuple intersect_mask; | |
136 | int count; | |
137 | ||
138 | intersect_mask.src.l3num = a->mask.src.l3num & b->mask.src.l3num; | |
139 | intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all; | |
140 | intersect_mask.dst.u.all = a->mask.dst.u.all & b->mask.dst.u.all; | |
141 | intersect_mask.dst.protonum = a->mask.dst.protonum | |
142 | & b->mask.dst.protonum; | |
143 | ||
144 | for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){ | |
145 | intersect_mask.src.u3.all[count] = | |
146 | a->mask.src.u3.all[count] & b->mask.src.u3.all[count]; | |
147 | } | |
148 | ||
149 | for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){ | |
150 | intersect_mask.dst.u3.all[count] = | |
151 | a->mask.dst.u3.all[count] & b->mask.dst.u3.all[count]; | |
152 | } | |
153 | ||
154 | return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask); | |
155 | } | |
156 | ||
157 | static inline int expect_matches(const struct nf_conntrack_expect *a, | |
158 | const struct nf_conntrack_expect *b) | |
159 | { | |
160 | return a->master == b->master | |
161 | && nf_ct_tuple_equal(&a->tuple, &b->tuple) | |
162 | && nf_ct_tuple_equal(&a->mask, &b->mask); | |
163 | } | |
164 | ||
165 | /* Generally a bad idea to call this: could have matched already. */ | |
166 | void nf_conntrack_unexpect_related(struct nf_conntrack_expect *exp) | |
167 | { | |
168 | struct nf_conntrack_expect *i; | |
169 | ||
170 | write_lock_bh(&nf_conntrack_lock); | |
171 | /* choose the the oldest expectation to evict */ | |
172 | list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) { | |
173 | if (expect_matches(i, exp) && del_timer(&i->timeout)) { | |
174 | nf_ct_unlink_expect(i); | |
175 | write_unlock_bh(&nf_conntrack_lock); | |
176 | nf_conntrack_expect_put(i); | |
177 | return; | |
178 | } | |
179 | } | |
180 | write_unlock_bh(&nf_conntrack_lock); | |
181 | } | |
182 | ||
183 | /* We don't increase the master conntrack refcount for non-fulfilled | |
184 | * conntracks. During the conntrack destruction, the expectations are | |
185 | * always killed before the conntrack itself */ | |
186 | struct nf_conntrack_expect *nf_conntrack_expect_alloc(struct nf_conn *me) | |
187 | { | |
188 | struct nf_conntrack_expect *new; | |
189 | ||
190 | new = kmem_cache_alloc(nf_conntrack_expect_cachep, GFP_ATOMIC); | |
191 | if (!new) | |
192 | return NULL; | |
193 | ||
194 | new->master = me; | |
195 | atomic_set(&new->use, 1); | |
196 | return new; | |
197 | } | |
198 | ||
d6a9b650 PM |
199 | void nf_conntrack_expect_init(struct nf_conntrack_expect *exp, int family, |
200 | union nf_conntrack_address *saddr, | |
201 | union nf_conntrack_address *daddr, | |
202 | u_int8_t proto, __be16 *src, __be16 *dst) | |
203 | { | |
204 | int len; | |
205 | ||
206 | if (family == AF_INET) | |
207 | len = 4; | |
208 | else | |
209 | len = 16; | |
210 | ||
211 | exp->flags = 0; | |
212 | exp->expectfn = NULL; | |
213 | exp->helper = NULL; | |
214 | exp->tuple.src.l3num = family; | |
215 | exp->tuple.dst.protonum = proto; | |
216 | exp->mask.src.l3num = 0xFFFF; | |
217 | exp->mask.dst.protonum = 0xFF; | |
218 | ||
219 | if (saddr) { | |
220 | memcpy(&exp->tuple.src.u3, saddr, len); | |
221 | if (sizeof(exp->tuple.src.u3) > len) | |
222 | /* address needs to be cleared for nf_ct_tuple_equal */ | |
223 | memset((void *)&exp->tuple.src.u3 + len, 0x00, | |
224 | sizeof(exp->tuple.src.u3) - len); | |
225 | memset(&exp->mask.src.u3, 0xFF, len); | |
226 | if (sizeof(exp->mask.src.u3) > len) | |
227 | memset((void *)&exp->mask.src.u3 + len, 0x00, | |
228 | sizeof(exp->mask.src.u3) - len); | |
229 | } else { | |
230 | memset(&exp->tuple.src.u3, 0x00, sizeof(exp->tuple.src.u3)); | |
231 | memset(&exp->mask.src.u3, 0x00, sizeof(exp->mask.src.u3)); | |
232 | } | |
233 | ||
234 | if (daddr) { | |
235 | memcpy(&exp->tuple.dst.u3, daddr, len); | |
236 | if (sizeof(exp->tuple.dst.u3) > len) | |
237 | /* address needs to be cleared for nf_ct_tuple_equal */ | |
238 | memset((void *)&exp->tuple.dst.u3 + len, 0x00, | |
239 | sizeof(exp->tuple.dst.u3) - len); | |
240 | memset(&exp->mask.dst.u3, 0xFF, len); | |
241 | if (sizeof(exp->mask.dst.u3) > len) | |
242 | memset((void *)&exp->mask.dst.u3 + len, 0x00, | |
243 | sizeof(exp->mask.dst.u3) - len); | |
244 | } else { | |
245 | memset(&exp->tuple.dst.u3, 0x00, sizeof(exp->tuple.dst.u3)); | |
246 | memset(&exp->mask.dst.u3, 0x00, sizeof(exp->mask.dst.u3)); | |
247 | } | |
248 | ||
249 | if (src) { | |
250 | exp->tuple.src.u.all = (__force u16)*src; | |
251 | exp->mask.src.u.all = 0xFFFF; | |
252 | } else { | |
253 | exp->tuple.src.u.all = 0; | |
254 | exp->mask.src.u.all = 0; | |
255 | } | |
256 | ||
257 | if (dst) { | |
258 | exp->tuple.dst.u.all = (__force u16)*dst; | |
259 | exp->mask.dst.u.all = 0xFFFF; | |
260 | } else { | |
261 | exp->tuple.dst.u.all = 0; | |
262 | exp->mask.dst.u.all = 0; | |
263 | } | |
264 | } | |
265 | EXPORT_SYMBOL_GPL(nf_conntrack_expect_init); | |
266 | ||
77ab9cff MJ |
267 | void nf_conntrack_expect_put(struct nf_conntrack_expect *exp) |
268 | { | |
269 | if (atomic_dec_and_test(&exp->use)) | |
270 | kmem_cache_free(nf_conntrack_expect_cachep, exp); | |
271 | } | |
272 | ||
273 | static void nf_conntrack_expect_insert(struct nf_conntrack_expect *exp) | |
274 | { | |
275 | struct nf_conn_help *master_help = nfct_help(exp->master); | |
276 | ||
277 | atomic_inc(&exp->use); | |
278 | master_help->expecting++; | |
279 | list_add(&exp->list, &nf_conntrack_expect_list); | |
280 | ||
281 | init_timer(&exp->timeout); | |
282 | exp->timeout.data = (unsigned long)exp; | |
283 | exp->timeout.function = expectation_timed_out; | |
284 | exp->timeout.expires = jiffies + master_help->helper->timeout * HZ; | |
285 | add_timer(&exp->timeout); | |
286 | ||
287 | exp->id = ++nf_conntrack_expect_next_id; | |
288 | atomic_inc(&exp->use); | |
289 | NF_CT_STAT_INC(expect_create); | |
290 | } | |
291 | ||
292 | /* Race with expectations being used means we could have none to find; OK. */ | |
293 | static void evict_oldest_expect(struct nf_conn *master) | |
294 | { | |
295 | struct nf_conntrack_expect *i; | |
296 | ||
297 | list_for_each_entry_reverse(i, &nf_conntrack_expect_list, list) { | |
298 | if (i->master == master) { | |
299 | if (del_timer(&i->timeout)) { | |
300 | nf_ct_unlink_expect(i); | |
301 | nf_conntrack_expect_put(i); | |
302 | } | |
303 | break; | |
304 | } | |
305 | } | |
306 | } | |
307 | ||
308 | static inline int refresh_timer(struct nf_conntrack_expect *i) | |
309 | { | |
310 | struct nf_conn_help *master_help = nfct_help(i->master); | |
311 | ||
312 | if (!del_timer(&i->timeout)) | |
313 | return 0; | |
314 | ||
315 | i->timeout.expires = jiffies + master_help->helper->timeout*HZ; | |
316 | add_timer(&i->timeout); | |
317 | return 1; | |
318 | } | |
319 | ||
320 | int nf_conntrack_expect_related(struct nf_conntrack_expect *expect) | |
321 | { | |
322 | struct nf_conntrack_expect *i; | |
323 | struct nf_conn *master = expect->master; | |
324 | struct nf_conn_help *master_help = nfct_help(master); | |
325 | int ret; | |
326 | ||
327 | NF_CT_ASSERT(master_help); | |
328 | ||
329 | write_lock_bh(&nf_conntrack_lock); | |
330 | list_for_each_entry(i, &nf_conntrack_expect_list, list) { | |
331 | if (expect_matches(i, expect)) { | |
332 | /* Refresh timer: if it's dying, ignore.. */ | |
333 | if (refresh_timer(i)) { | |
334 | ret = 0; | |
335 | goto out; | |
336 | } | |
337 | } else if (expect_clash(i, expect)) { | |
338 | ret = -EBUSY; | |
339 | goto out; | |
340 | } | |
341 | } | |
342 | /* Will be over limit? */ | |
343 | if (master_help->helper->max_expected && | |
344 | master_help->expecting >= master_help->helper->max_expected) | |
345 | evict_oldest_expect(master); | |
346 | ||
347 | nf_conntrack_expect_insert(expect); | |
348 | nf_conntrack_expect_event(IPEXP_NEW, expect); | |
349 | ret = 0; | |
350 | out: | |
351 | write_unlock_bh(&nf_conntrack_lock); | |
352 | return ret; | |
353 | } | |
354 | ||
355 | #ifdef CONFIG_PROC_FS | |
356 | static void *exp_seq_start(struct seq_file *s, loff_t *pos) | |
357 | { | |
358 | struct list_head *e = &nf_conntrack_expect_list; | |
359 | loff_t i; | |
360 | ||
361 | /* strange seq_file api calls stop even if we fail, | |
362 | * thus we need to grab lock since stop unlocks */ | |
363 | read_lock_bh(&nf_conntrack_lock); | |
364 | ||
365 | if (list_empty(e)) | |
366 | return NULL; | |
367 | ||
368 | for (i = 0; i <= *pos; i++) { | |
369 | e = e->next; | |
370 | if (e == &nf_conntrack_expect_list) | |
371 | return NULL; | |
372 | } | |
373 | return e; | |
374 | } | |
375 | ||
376 | static void *exp_seq_next(struct seq_file *s, void *v, loff_t *pos) | |
377 | { | |
378 | struct list_head *e = v; | |
379 | ||
380 | ++*pos; | |
381 | e = e->next; | |
382 | ||
383 | if (e == &nf_conntrack_expect_list) | |
384 | return NULL; | |
385 | ||
386 | return e; | |
387 | } | |
388 | ||
389 | static void exp_seq_stop(struct seq_file *s, void *v) | |
390 | { | |
391 | read_unlock_bh(&nf_conntrack_lock); | |
392 | } | |
393 | ||
394 | static int exp_seq_show(struct seq_file *s, void *v) | |
395 | { | |
396 | struct nf_conntrack_expect *expect = v; | |
397 | ||
398 | if (expect->timeout.function) | |
399 | seq_printf(s, "%ld ", timer_pending(&expect->timeout) | |
400 | ? (long)(expect->timeout.expires - jiffies)/HZ : 0); | |
401 | else | |
402 | seq_printf(s, "- "); | |
403 | seq_printf(s, "l3proto = %u proto=%u ", | |
404 | expect->tuple.src.l3num, | |
405 | expect->tuple.dst.protonum); | |
406 | print_tuple(s, &expect->tuple, | |
407 | __nf_ct_l3proto_find(expect->tuple.src.l3num), | |
605dcad6 | 408 | __nf_ct_l4proto_find(expect->tuple.src.l3num, |
77ab9cff MJ |
409 | expect->tuple.dst.protonum)); |
410 | return seq_putc(s, '\n'); | |
411 | } | |
412 | ||
413 | static struct seq_operations exp_seq_ops = { | |
414 | .start = exp_seq_start, | |
415 | .next = exp_seq_next, | |
416 | .stop = exp_seq_stop, | |
417 | .show = exp_seq_show | |
418 | }; | |
419 | ||
420 | static int exp_open(struct inode *inode, struct file *file) | |
421 | { | |
422 | return seq_open(file, &exp_seq_ops); | |
423 | } | |
424 | ||
425 | struct file_operations exp_file_ops = { | |
426 | .owner = THIS_MODULE, | |
427 | .open = exp_open, | |
428 | .read = seq_read, | |
429 | .llseek = seq_lseek, | |
430 | .release = seq_release | |
431 | }; | |
432 | #endif /* CONFIG_PROC_FS */ |