[NETFILTER]: nf_conntrack_expect: introduce nf_conntrack_expect_max sysct
[linux-3.10.git] / net / netfilter / nf_conntrack_expect.c
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 #include <linux/jhash.h>
23
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_core.h>
26 #include <net/netfilter/nf_conntrack_expect.h>
27 #include <net/netfilter/nf_conntrack_helper.h>
28 #include <net/netfilter/nf_conntrack_tuple.h>
29
30 struct hlist_head *nf_ct_expect_hash __read_mostly;
31 EXPORT_SYMBOL_GPL(nf_ct_expect_hash);
32
33 unsigned int nf_ct_expect_hsize __read_mostly;
34 EXPORT_SYMBOL_GPL(nf_ct_expect_hsize);
35
36 static unsigned int nf_ct_expect_hash_rnd __read_mostly;
37 static unsigned int nf_ct_expect_count;
38 unsigned int nf_ct_expect_max __read_mostly;
39 static int nf_ct_expect_hash_rnd_initted __read_mostly;
40 static int nf_ct_expect_vmalloc;
41
42 static struct kmem_cache *nf_ct_expect_cachep __read_mostly;
43 static unsigned int nf_ct_expect_next_id;
44
45 /* nf_conntrack_expect helper functions */
46 void nf_ct_unlink_expect(struct nf_conntrack_expect *exp)
47 {
48         struct nf_conn_help *master_help = nfct_help(exp->master);
49
50         NF_CT_ASSERT(master_help);
51         NF_CT_ASSERT(!timer_pending(&exp->timeout));
52
53         hlist_del(&exp->hnode);
54         nf_ct_expect_count--;
55
56         hlist_del(&exp->lnode);
57         master_help->expecting--;
58         nf_ct_expect_put(exp);
59
60         NF_CT_STAT_INC(expect_delete);
61 }
62 EXPORT_SYMBOL_GPL(nf_ct_unlink_expect);
63
64 static void nf_ct_expectation_timed_out(unsigned long ul_expect)
65 {
66         struct nf_conntrack_expect *exp = (void *)ul_expect;
67
68         write_lock_bh(&nf_conntrack_lock);
69         nf_ct_unlink_expect(exp);
70         write_unlock_bh(&nf_conntrack_lock);
71         nf_ct_expect_put(exp);
72 }
73
74 static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple)
75 {
76         if (unlikely(!nf_ct_expect_hash_rnd_initted)) {
77                 get_random_bytes(&nf_ct_expect_hash_rnd, 4);
78                 nf_ct_expect_hash_rnd_initted = 1;
79         }
80
81         return jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
82                       (((tuple->dst.protonum ^ tuple->src.l3num) << 16) |
83                        tuple->dst.u.all) ^ nf_ct_expect_hash_rnd) %
84                nf_ct_expect_hsize;
85 }
86
87 struct nf_conntrack_expect *
88 __nf_ct_expect_find(const struct nf_conntrack_tuple *tuple)
89 {
90         struct nf_conntrack_expect *i;
91         struct hlist_node *n;
92         unsigned int h;
93
94         if (!nf_ct_expect_count)
95                 return NULL;
96
97         h = nf_ct_expect_dst_hash(tuple);
98         hlist_for_each_entry(i, n, &nf_ct_expect_hash[h], hnode) {
99                 if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
100                         return i;
101         }
102         return NULL;
103 }
104 EXPORT_SYMBOL_GPL(__nf_ct_expect_find);
105
106 /* Just find a expectation corresponding to a tuple. */
107 struct nf_conntrack_expect *
108 nf_ct_expect_find_get(const struct nf_conntrack_tuple *tuple)
109 {
110         struct nf_conntrack_expect *i;
111
112         read_lock_bh(&nf_conntrack_lock);
113         i = __nf_ct_expect_find(tuple);
114         if (i)
115                 atomic_inc(&i->use);
116         read_unlock_bh(&nf_conntrack_lock);
117
118         return i;
119 }
120 EXPORT_SYMBOL_GPL(nf_ct_expect_find_get);
121
122 /* If an expectation for this connection is found, it gets delete from
123  * global list then returned. */
124 struct nf_conntrack_expect *
125 nf_ct_find_expectation(const struct nf_conntrack_tuple *tuple)
126 {
127         struct nf_conntrack_expect *exp;
128
129         exp = __nf_ct_expect_find(tuple);
130         if (!exp)
131                 return NULL;
132
133         /* If master is not in hash table yet (ie. packet hasn't left
134            this machine yet), how can other end know about expected?
135            Hence these are not the droids you are looking for (if
136            master ct never got confirmed, we'd hold a reference to it
137            and weird things would happen to future packets). */
138         if (!nf_ct_is_confirmed(exp->master))
139                 return NULL;
140
141         if (exp->flags & NF_CT_EXPECT_PERMANENT) {
142                 atomic_inc(&exp->use);
143                 return exp;
144         } else if (del_timer(&exp->timeout)) {
145                 nf_ct_unlink_expect(exp);
146                 return exp;
147         }
148
149         return NULL;
150 }
151
152 /* delete all expectations for this conntrack */
153 void nf_ct_remove_expectations(struct nf_conn *ct)
154 {
155         struct nf_conn_help *help = nfct_help(ct);
156         struct nf_conntrack_expect *exp;
157         struct hlist_node *n, *next;
158
159         /* Optimization: most connection never expect any others. */
160         if (!help || help->expecting == 0)
161                 return;
162
163         hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
164                 if (del_timer(&exp->timeout)) {
165                         nf_ct_unlink_expect(exp);
166                         nf_ct_expect_put(exp);
167                 }
168         }
169 }
170 EXPORT_SYMBOL_GPL(nf_ct_remove_expectations);
171
172 /* Would two expected things clash? */
173 static inline int expect_clash(const struct nf_conntrack_expect *a,
174                                const struct nf_conntrack_expect *b)
175 {
176         /* Part covered by intersection of masks must be unequal,
177            otherwise they clash */
178         struct nf_conntrack_tuple_mask intersect_mask;
179         int count;
180
181         intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all;
182
183         for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
184                 intersect_mask.src.u3.all[count] =
185                         a->mask.src.u3.all[count] & b->mask.src.u3.all[count];
186         }
187
188         return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask);
189 }
190
191 static inline int expect_matches(const struct nf_conntrack_expect *a,
192                                  const struct nf_conntrack_expect *b)
193 {
194         return a->master == b->master
195                 && nf_ct_tuple_equal(&a->tuple, &b->tuple)
196                 && nf_ct_tuple_mask_equal(&a->mask, &b->mask);
197 }
198
199 /* Generally a bad idea to call this: could have matched already. */
200 void nf_ct_unexpect_related(struct nf_conntrack_expect *exp)
201 {
202         write_lock_bh(&nf_conntrack_lock);
203         if (del_timer(&exp->timeout)) {
204                 nf_ct_unlink_expect(exp);
205                 nf_ct_expect_put(exp);
206         }
207         write_unlock_bh(&nf_conntrack_lock);
208 }
209 EXPORT_SYMBOL_GPL(nf_ct_unexpect_related);
210
211 /* We don't increase the master conntrack refcount for non-fulfilled
212  * conntracks. During the conntrack destruction, the expectations are
213  * always killed before the conntrack itself */
214 struct nf_conntrack_expect *nf_ct_expect_alloc(struct nf_conn *me)
215 {
216         struct nf_conntrack_expect *new;
217
218         new = kmem_cache_alloc(nf_ct_expect_cachep, GFP_ATOMIC);
219         if (!new)
220                 return NULL;
221
222         new->master = me;
223         atomic_set(&new->use, 1);
224         return new;
225 }
226 EXPORT_SYMBOL_GPL(nf_ct_expect_alloc);
227
228 void nf_ct_expect_init(struct nf_conntrack_expect *exp, int family,
229                        union nf_conntrack_address *saddr,
230                        union nf_conntrack_address *daddr,
231                        u_int8_t proto, __be16 *src, __be16 *dst)
232 {
233         int len;
234
235         if (family == AF_INET)
236                 len = 4;
237         else
238                 len = 16;
239
240         exp->flags = 0;
241         exp->expectfn = NULL;
242         exp->helper = NULL;
243         exp->tuple.src.l3num = family;
244         exp->tuple.dst.protonum = proto;
245
246         if (saddr) {
247                 memcpy(&exp->tuple.src.u3, saddr, len);
248                 if (sizeof(exp->tuple.src.u3) > len)
249                         /* address needs to be cleared for nf_ct_tuple_equal */
250                         memset((void *)&exp->tuple.src.u3 + len, 0x00,
251                                sizeof(exp->tuple.src.u3) - len);
252                 memset(&exp->mask.src.u3, 0xFF, len);
253                 if (sizeof(exp->mask.src.u3) > len)
254                         memset((void *)&exp->mask.src.u3 + len, 0x00,
255                                sizeof(exp->mask.src.u3) - len);
256         } else {
257                 memset(&exp->tuple.src.u3, 0x00, sizeof(exp->tuple.src.u3));
258                 memset(&exp->mask.src.u3, 0x00, sizeof(exp->mask.src.u3));
259         }
260
261         if (src) {
262                 exp->tuple.src.u.all = (__force u16)*src;
263                 exp->mask.src.u.all = 0xFFFF;
264         } else {
265                 exp->tuple.src.u.all = 0;
266                 exp->mask.src.u.all = 0;
267         }
268
269         memcpy(&exp->tuple.dst.u3, daddr, len);
270         if (sizeof(exp->tuple.dst.u3) > len)
271                 /* address needs to be cleared for nf_ct_tuple_equal */
272                 memset((void *)&exp->tuple.dst.u3 + len, 0x00,
273                        sizeof(exp->tuple.dst.u3) - len);
274
275         exp->tuple.dst.u.all = (__force u16)*dst;
276 }
277 EXPORT_SYMBOL_GPL(nf_ct_expect_init);
278
279 void nf_ct_expect_put(struct nf_conntrack_expect *exp)
280 {
281         if (atomic_dec_and_test(&exp->use))
282                 kmem_cache_free(nf_ct_expect_cachep, exp);
283 }
284 EXPORT_SYMBOL_GPL(nf_ct_expect_put);
285
286 static void nf_ct_expect_insert(struct nf_conntrack_expect *exp)
287 {
288         struct nf_conn_help *master_help = nfct_help(exp->master);
289         unsigned int h = nf_ct_expect_dst_hash(&exp->tuple);
290
291         atomic_inc(&exp->use);
292
293         hlist_add_head(&exp->lnode, &master_help->expectations);
294         master_help->expecting++;
295
296         hlist_add_head(&exp->hnode, &nf_ct_expect_hash[h]);
297         nf_ct_expect_count++;
298
299         setup_timer(&exp->timeout, nf_ct_expectation_timed_out,
300                     (unsigned long)exp);
301         exp->timeout.expires = jiffies + master_help->helper->timeout * HZ;
302         add_timer(&exp->timeout);
303
304         exp->id = ++nf_ct_expect_next_id;
305         atomic_inc(&exp->use);
306         NF_CT_STAT_INC(expect_create);
307 }
308
309 /* Race with expectations being used means we could have none to find; OK. */
310 static void evict_oldest_expect(struct nf_conn *master)
311 {
312         struct nf_conn_help *master_help = nfct_help(master);
313         struct nf_conntrack_expect *exp = NULL;
314         struct hlist_node *n;
315
316         hlist_for_each_entry(exp, n, &master_help->expectations, lnode)
317                 ; /* nothing */
318
319         if (exp && del_timer(&exp->timeout)) {
320                 nf_ct_unlink_expect(exp);
321                 nf_ct_expect_put(exp);
322         }
323 }
324
325 static inline int refresh_timer(struct nf_conntrack_expect *i)
326 {
327         struct nf_conn_help *master_help = nfct_help(i->master);
328
329         if (!del_timer(&i->timeout))
330                 return 0;
331
332         i->timeout.expires = jiffies + master_help->helper->timeout*HZ;
333         add_timer(&i->timeout);
334         return 1;
335 }
336
337 int nf_ct_expect_related(struct nf_conntrack_expect *expect)
338 {
339         struct nf_conntrack_expect *i;
340         struct nf_conn *master = expect->master;
341         struct nf_conn_help *master_help = nfct_help(master);
342         struct hlist_node *n;
343         unsigned int h;
344         int ret;
345
346         NF_CT_ASSERT(master_help);
347
348         write_lock_bh(&nf_conntrack_lock);
349         if (!master_help->helper) {
350                 ret = -ESHUTDOWN;
351                 goto out;
352         }
353         h = nf_ct_expect_dst_hash(&expect->tuple);
354         hlist_for_each_entry(i, n, &nf_ct_expect_hash[h], hnode) {
355                 if (expect_matches(i, expect)) {
356                         /* Refresh timer: if it's dying, ignore.. */
357                         if (refresh_timer(i)) {
358                                 ret = 0;
359                                 goto out;
360                         }
361                 } else if (expect_clash(i, expect)) {
362                         ret = -EBUSY;
363                         goto out;
364                 }
365         }
366         /* Will be over limit? */
367         if (master_help->helper->max_expected &&
368             master_help->expecting >= master_help->helper->max_expected)
369                 evict_oldest_expect(master);
370
371         if (nf_ct_expect_count >= nf_ct_expect_max) {
372                 if (net_ratelimit())
373                         printk(KERN_WARNING
374                                "nf_conntrack: expectation table full");
375                 ret = -EMFILE;
376                 goto out;
377         }
378
379         nf_ct_expect_insert(expect);
380         nf_ct_expect_event(IPEXP_NEW, expect);
381         ret = 0;
382 out:
383         write_unlock_bh(&nf_conntrack_lock);
384         return ret;
385 }
386 EXPORT_SYMBOL_GPL(nf_ct_expect_related);
387
388 #ifdef CONFIG_PROC_FS
389 struct ct_expect_iter_state {
390         unsigned int bucket;
391 };
392
393 static struct hlist_node *ct_expect_get_first(struct seq_file *seq)
394 {
395         struct ct_expect_iter_state *st = seq->private;
396
397         for (st->bucket = 0; st->bucket < nf_ct_expect_hsize; st->bucket++) {
398                 if (!hlist_empty(&nf_ct_expect_hash[st->bucket]))
399                         return nf_ct_expect_hash[st->bucket].first;
400         }
401         return NULL;
402 }
403
404 static struct hlist_node *ct_expect_get_next(struct seq_file *seq,
405                                              struct hlist_node *head)
406 {
407         struct ct_expect_iter_state *st = seq->private;
408
409         head = head->next;
410         while (head == NULL) {
411                 if (++st->bucket >= nf_ct_expect_hsize)
412                         return NULL;
413                 head = nf_ct_expect_hash[st->bucket].first;
414         }
415         return head;
416 }
417
418 static struct hlist_node *ct_expect_get_idx(struct seq_file *seq, loff_t pos)
419 {
420         struct hlist_node *head = ct_expect_get_first(seq);
421
422         if (head)
423                 while (pos && (head = ct_expect_get_next(seq, head)))
424                         pos--;
425         return pos ? NULL : head;
426 }
427
428 static void *exp_seq_start(struct seq_file *seq, loff_t *pos)
429 {
430         read_lock_bh(&nf_conntrack_lock);
431         return ct_expect_get_idx(seq, *pos);
432 }
433
434 static void *exp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
435 {
436         (*pos)++;
437         return ct_expect_get_next(seq, v);
438 }
439
440 static void exp_seq_stop(struct seq_file *seq, void *v)
441 {
442         read_unlock_bh(&nf_conntrack_lock);
443 }
444
445 static int exp_seq_show(struct seq_file *s, void *v)
446 {
447         struct nf_conntrack_expect *expect;
448         struct hlist_node *n = v;
449
450         expect = hlist_entry(n, struct nf_conntrack_expect, hnode);
451
452         if (expect->timeout.function)
453                 seq_printf(s, "%ld ", timer_pending(&expect->timeout)
454                            ? (long)(expect->timeout.expires - jiffies)/HZ : 0);
455         else
456                 seq_printf(s, "- ");
457         seq_printf(s, "l3proto = %u proto=%u ",
458                    expect->tuple.src.l3num,
459                    expect->tuple.dst.protonum);
460         print_tuple(s, &expect->tuple,
461                     __nf_ct_l3proto_find(expect->tuple.src.l3num),
462                     __nf_ct_l4proto_find(expect->tuple.src.l3num,
463                                        expect->tuple.dst.protonum));
464         return seq_putc(s, '\n');
465 }
466
467 static struct seq_operations exp_seq_ops = {
468         .start = exp_seq_start,
469         .next = exp_seq_next,
470         .stop = exp_seq_stop,
471         .show = exp_seq_show
472 };
473
474 static int exp_open(struct inode *inode, struct file *file)
475 {
476         struct seq_file *seq;
477         struct ct_expect_iter_state *st;
478         int ret;
479
480         st = kmalloc(sizeof(struct ct_expect_iter_state), GFP_KERNEL);
481         if (st == NULL)
482                 return -ENOMEM;
483         ret = seq_open(file, &exp_seq_ops);
484         if (ret)
485                 goto out_free;
486         seq          = file->private_data;
487         seq->private = st;
488         memset(st, 0, sizeof(struct ct_expect_iter_state));
489         return ret;
490 out_free:
491         kfree(st);
492         return ret;
493 }
494
495 static const struct file_operations exp_file_ops = {
496         .owner   = THIS_MODULE,
497         .open    = exp_open,
498         .read    = seq_read,
499         .llseek  = seq_lseek,
500         .release = seq_release_private,
501 };
502 #endif /* CONFIG_PROC_FS */
503
504 static int __init exp_proc_init(void)
505 {
506 #ifdef CONFIG_PROC_FS
507         struct proc_dir_entry *proc;
508
509         proc = proc_net_fops_create("nf_conntrack_expect", 0440, &exp_file_ops);
510         if (!proc)
511                 return -ENOMEM;
512 #endif /* CONFIG_PROC_FS */
513         return 0;
514 }
515
516 static void exp_proc_remove(void)
517 {
518 #ifdef CONFIG_PROC_FS
519         proc_net_remove("nf_conntrack_expect");
520 #endif /* CONFIG_PROC_FS */
521 }
522
523 module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0600);
524
525 int __init nf_conntrack_expect_init(void)
526 {
527         int err = -ENOMEM;
528
529         if (!nf_ct_expect_hsize) {
530                 nf_ct_expect_hsize = nf_conntrack_htable_size / 256;
531                 if (!nf_ct_expect_hsize)
532                         nf_ct_expect_hsize = 1;
533         }
534         nf_ct_expect_max = nf_ct_expect_hsize * 4;
535
536         nf_ct_expect_hash = nf_ct_alloc_hashtable(&nf_ct_expect_hsize,
537                                                   &nf_ct_expect_vmalloc);
538         if (nf_ct_expect_hash == NULL)
539                 goto err1;
540
541         nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect",
542                                         sizeof(struct nf_conntrack_expect),
543                                         0, 0, NULL, NULL);
544         if (!nf_ct_expect_cachep)
545                 goto err2;
546
547         err = exp_proc_init();
548         if (err < 0)
549                 goto err3;
550
551         return 0;
552
553 err3:
554         nf_ct_free_hashtable(nf_ct_expect_hash, nf_ct_expect_vmalloc,
555                              nf_ct_expect_hsize);
556 err2:
557         kmem_cache_destroy(nf_ct_expect_cachep);
558 err1:
559         return err;
560 }
561
562 void nf_conntrack_expect_fini(void)
563 {
564         exp_proc_remove();
565         kmem_cache_destroy(nf_ct_expect_cachep);
566         nf_ct_free_hashtable(nf_ct_expect_hash, nf_ct_expect_vmalloc,
567                              nf_ct_expect_hsize);
568 }