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 #include <net/net_namespace.h>
  24
  25 #include <net/netfilter/nf_conntrack.h>
  26 #include <net/netfilter/nf_conntrack_core.h>
  27 #include <net/netfilter/nf_conntrack_expect.h>
  28 #include <net/netfilter/nf_conntrack_helper.h>
  29 #include <net/netfilter/nf_conntrack_tuple.h>
  30
  31 unsigned int nf_ct_expect_hsize __read_mostly;
  32 EXPORT_SYMBOL_GPL(nf_ct_expect_hsize);
  33
  34 static unsigned int nf_ct_expect_hash_rnd __read_mostly;
  35 unsigned int nf_ct_expect_max __read_mostly;
  36 static int nf_ct_expect_hash_rnd_initted __read_mostly;
  37
  38 static struct kmem_cache *nf_ct_expect_cachep __read_mostly;
  39
  40 /* nf_conntrack_expect helper functions */
  41 void nf_ct_unlink_expect(struct nf_conntrack_expect *exp)
  42 {
  43         struct nf_conn_help *master_help = nfct_help(exp->master);
  44         struct net *net = nf_ct_exp_net(exp);
  45
  46         NF_CT_ASSERT(master_help);
  47         NF_CT_ASSERT(!timer_pending(&exp->timeout));
  48
  49         hlist_del_rcu(&exp->hnode);
  50         net->ct.expect_count--;
  51
  52         hlist_del(&exp->lnode);
  53         master_help->expecting[exp->class]--;
  54         nf_ct_expect_put(exp);
  55
  56         NF_CT_STAT_INC(expect_delete);
  57 }
  58 EXPORT_SYMBOL_GPL(nf_ct_unlink_expect);
  59
  60 static void nf_ct_expectation_timed_out(unsigned long ul_expect)
  61 {
  62         struct nf_conntrack_expect *exp = (void *)ul_expect;
  63
  64         spin_lock_bh(&nf_conntrack_lock);
  65         nf_ct_unlink_expect(exp);
  66         spin_unlock_bh(&nf_conntrack_lock);
  67         nf_ct_expect_put(exp);
  68 }
  69
  70 static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple)
  71 {
  72         unsigned int hash;
  73
  74         if (unlikely(!nf_ct_expect_hash_rnd_initted)) {
  75                 get_random_bytes(&nf_ct_expect_hash_rnd, 4);
  76                 nf_ct_expect_hash_rnd_initted = 1;
  77         }
  78
  79         hash = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),
  80                       (((tuple->dst.protonum ^ tuple->src.l3num) << 16) |
  81                        (__force __u16)tuple->dst.u.all) ^ nf_ct_expect_hash_rnd);
  82         return ((u64)hash * nf_ct_expect_hsize) >> 32;
  83 }
  84
  85 struct nf_conntrack_expect *
  86 __nf_ct_expect_find(struct net *net, const struct nf_conntrack_tuple *tuple)
  87 {
  88         struct nf_conntrack_expect *i;
  89         struct hlist_node *n;
  90         unsigned int h;
  91
  92         if (!net->ct.expect_count)
  93                 return NULL;
  94
  95         h = nf_ct_expect_dst_hash(tuple);
  96         hlist_for_each_entry_rcu(i, n, &net->ct.expect_hash[h], hnode) {
  97                 if (nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask))
  98                         return i;
  99         }
 100         return NULL;
 101 }
 102 EXPORT_SYMBOL_GPL(__nf_ct_expect_find);
 103
 104 /* Just find a expectation corresponding to a tuple. */
 105 struct nf_conntrack_expect *
 106 nf_ct_expect_find_get(struct net *net, const struct nf_conntrack_tuple *tuple)
 107 {
 108         struct nf_conntrack_expect *i;
 109
 110         rcu_read_lock();
 111         i = __nf_ct_expect_find(net, tuple);
 112         if (i && !atomic_inc_not_zero(&i->use))
 113                 i = NULL;
 114         rcu_read_unlock();
 115
 116         return i;
 117 }
 118 EXPORT_SYMBOL_GPL(nf_ct_expect_find_get);
 119
 120 /* If an expectation for this connection is found, it gets delete from
 121  * global list then returned. */
 122 struct nf_conntrack_expect *
 123 nf_ct_find_expectation(struct net *net, const struct nf_conntrack_tuple *tuple)
 124 {
 125         struct nf_conntrack_expect *i, *exp = NULL;
 126         struct hlist_node *n;
 127         unsigned int h;
 128
 129         if (!net->ct.expect_count)
 130                 return NULL;
 131
 132         h = nf_ct_expect_dst_hash(tuple);
 133         hlist_for_each_entry(i, n, &net->ct.expect_hash[h], hnode) {
 134                 if (!(i->flags & NF_CT_EXPECT_INACTIVE) &&
 135                     nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) {
 136                         exp = i;
 137                         break;
 138                 }
 139         }
 140         if (!exp)
 141                 return NULL;
 142
 143         /* If master is not in hash table yet (ie. packet hasn't left
 144            this machine yet), how can other end know about expected?
 145            Hence these are not the droids you are looking for (if
 146            master ct never got confirmed, we'd hold a reference to it
 147            and weird things would happen to future packets). */
 148         if (!nf_ct_is_confirmed(exp->master))
 149                 return NULL;
 150
 151         if (exp->flags & NF_CT_EXPECT_PERMANENT) {
 152                 atomic_inc(&exp->use);
 153                 return exp;
 154         } else if (del_timer(&exp->timeout)) {
 155                 nf_ct_unlink_expect(exp);
 156                 return exp;
 157         }
 158
 159         return NULL;
 160 }
 161
 162 /* delete all expectations for this conntrack */
 163 void nf_ct_remove_expectations(struct nf_conn *ct)
 164 {
 165         struct nf_conn_help *help = nfct_help(ct);
 166         struct nf_conntrack_expect *exp;
 167         struct hlist_node *n, *next;
 168
 169         /* Optimization: most connection never expect any others. */
 170         if (!help)
 171                 return;
 172
 173         hlist_for_each_entry_safe(exp, n, next, &help->expectations, lnode) {
 174                 if (del_timer(&exp->timeout)) {
 175                         nf_ct_unlink_expect(exp);
 176                         nf_ct_expect_put(exp);
 177                 }
 178         }
 179 }
 180 EXPORT_SYMBOL_GPL(nf_ct_remove_expectations);
 181
 182 /* Would two expected things clash? */
 183 static inline int expect_clash(const struct nf_conntrack_expect *a,
 184                                const struct nf_conntrack_expect *b)
 185 {
 186         /* Part covered by intersection of masks must be unequal,
 187            otherwise they clash */
 188         struct nf_conntrack_tuple_mask intersect_mask;
 189         int count;
 190
 191         intersect_mask.src.u.all = a->mask.src.u.all & b->mask.src.u.all;
 192
 193         for (count = 0; count < NF_CT_TUPLE_L3SIZE; count++){
 194                 intersect_mask.src.u3.all[count] =
 195                         a->mask.src.u3.all[count] & b->mask.src.u3.all[count];
 196         }
 197
 198         return nf_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask);
 199 }
 200
 201 static inline int expect_matches(const struct nf_conntrack_expect *a,
 202                                  const struct nf_conntrack_expect *b)
 203 {
 204         return a->master == b->master && a->class == b->class
 205                 && nf_ct_tuple_equal(&a->tuple, &b->tuple)
 206                 && nf_ct_tuple_mask_equal(&a->mask, &b->mask);
 207 }
 208
 209 /* Generally a bad idea to call this: could have matched already. */
 210 void nf_ct_unexpect_related(struct nf_conntrack_expect *exp)
 211 {
 212         spin_lock_bh(&nf_conntrack_lock);
 213         if (del_timer(&exp->timeout)) {
 214                 nf_ct_unlink_expect(exp);
 215                 nf_ct_expect_put(exp);
 216         }
 217         spin_unlock_bh(&nf_conntrack_lock);
 218 }
 219 EXPORT_SYMBOL_GPL(nf_ct_unexpect_related);
 220
 221 /* We don't increase the master conntrack refcount for non-fulfilled
 222  * conntracks. During the conntrack destruction, the expectations are
 223  * always killed before the conntrack itself */
 224 struct nf_conntrack_expect *nf_ct_expect_alloc(struct nf_conn *me)
 225 {
 226         struct nf_conntrack_expect *new;
 227
 228         new = kmem_cache_alloc(nf_ct_expect_cachep, GFP_ATOMIC);
 229         if (!new)
 230                 return NULL;
 231
 232         new->master = me;
 233         atomic_set(&new->use, 1);
 234         INIT_RCU_HEAD(&new->rcu);
 235         return new;
 236 }
 237 EXPORT_SYMBOL_GPL(nf_ct_expect_alloc);
 238
 239 void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class,
 240                        u_int8_t family,
 241                        const union nf_inet_addr *saddr,
 242                        const union nf_inet_addr *daddr,
 243                        u_int8_t proto, const __be16 *src, const __be16 *dst)
 244 {
 245         int len;
 246
 247         if (family == AF_INET)
 248                 len = 4;
 249         else
 250                 len = 16;
 251
 252         exp->flags = 0;
 253         exp->class = class;
 254         exp->expectfn = NULL;
 255         exp->helper = NULL;
 256         exp->tuple.src.l3num = family;
 257         exp->tuple.dst.protonum = proto;
 258
 259         if (saddr) {
 260                 memcpy(&exp->tuple.src.u3, saddr, len);
 261                 if (sizeof(exp->tuple.src.u3) > len)
 262                         /* address needs to be cleared for nf_ct_tuple_equal */
 263                         memset((void *)&exp->tuple.src.u3 + len, 0x00,
 264                                sizeof(exp->tuple.src.u3) - len);
 265                 memset(&exp->mask.src.u3, 0xFF, len);
 266                 if (sizeof(exp->mask.src.u3) > len)
 267                         memset((void *)&exp->mask.src.u3 + len, 0x00,
 268                                sizeof(exp->mask.src.u3) - len);
 269         } else {
 270                 memset(&exp->tuple.src.u3, 0x00, sizeof(exp->tuple.src.u3));
 271                 memset(&exp->mask.src.u3, 0x00, sizeof(exp->mask.src.u3));
 272         }
 273
 274         if (src) {
 275                 exp->tuple.src.u.all = *src;
 276                 exp->mask.src.u.all = htons(0xFFFF);
 277         } else {
 278                 exp->tuple.src.u.all = 0;
 279                 exp->mask.src.u.all = 0;
 280         }
 281
 282         memcpy(&exp->tuple.dst.u3, daddr, len);
 283         if (sizeof(exp->tuple.dst.u3) > len)
 284                 /* address needs to be cleared for nf_ct_tuple_equal */
 285                 memset((void *)&exp->tuple.dst.u3 + len, 0x00,
 286                        sizeof(exp->tuple.dst.u3) - len);
 287
 288         exp->tuple.dst.u.all = *dst;
 289 }
 290 EXPORT_SYMBOL_GPL(nf_ct_expect_init);
 291
 292 static void nf_ct_expect_free_rcu(struct rcu_head *head)
 293 {
 294         struct nf_conntrack_expect *exp;
 295
 296         exp = container_of(head, struct nf_conntrack_expect, rcu);
 297         kmem_cache_free(nf_ct_expect_cachep, exp);
 298 }
 299
 300 void nf_ct_expect_put(struct nf_conntrack_expect *exp)
 301 {
 302         if (atomic_dec_and_test(&exp->use))
 303                 call_rcu(&exp->rcu, nf_ct_expect_free_rcu);
 304 }
 305 EXPORT_SYMBOL_GPL(nf_ct_expect_put);
 306
 307 static void nf_ct_expect_insert(struct nf_conntrack_expect *exp)
 308 {
 309         struct nf_conn_help *master_help = nfct_help(exp->master);
 310         struct net *net = nf_ct_exp_net(exp);
 311         const struct nf_conntrack_expect_policy *p;
 312         unsigned int h = nf_ct_expect_dst_hash(&exp->tuple);
 313
 314         atomic_inc(&exp->use);
 315
 316         hlist_add_head(&exp->lnode, &master_help->expectations);
 317         master_help->expecting[exp->class]++;
 318
 319         hlist_add_head_rcu(&exp->hnode, &net->ct.expect_hash[h]);
 320         net->ct.expect_count++;
 321
 322         setup_timer(&exp->timeout, nf_ct_expectation_timed_out,
 323                     (unsigned long)exp);
 324         p = &master_help->helper->expect_policy[exp->class];
 325         exp->timeout.expires = jiffies + p->timeout * HZ;
 326         add_timer(&exp->timeout);
 327
 328         atomic_inc(&exp->use);
 329         NF_CT_STAT_INC(expect_create);
 330 }
 331
 332 /* Race with expectations being used means we could have none to find; OK. */
 333 static void evict_oldest_expect(struct nf_conn *master,
 334                                 struct nf_conntrack_expect *new)
 335 {
 336         struct nf_conn_help *master_help = nfct_help(master);
 337         struct nf_conntrack_expect *exp, *last = NULL;
 338         struct hlist_node *n;
 339
 340         hlist_for_each_entry(exp, n, &master_help->expectations, lnode) {
 341                 if (exp->class == new->class)
 342                         last = exp;
 343         }
 344
 345         if (last && del_timer(&last->timeout)) {
 346                 nf_ct_unlink_expect(last);
 347                 nf_ct_expect_put(last);
 348         }
 349 }
 350
 351 static inline int refresh_timer(struct nf_conntrack_expect *i)
 352 {
 353         struct nf_conn_help *master_help = nfct_help(i->master);
 354         const struct nf_conntrack_expect_policy *p;
 355
 356         if (!del_timer(&i->timeout))
 357                 return 0;
 358
 359         p = &master_help->helper->expect_policy[i->class];
 360         i->timeout.expires = jiffies + p->timeout * HZ;
 361         add_timer(&i->timeout);
 362         return 1;
 363 }
 364
 365 int nf_ct_expect_related(struct nf_conntrack_expect *expect)
 366 {
 367         const struct nf_conntrack_expect_policy *p;
 368         struct nf_conntrack_expect *i;
 369         struct nf_conn *master = expect->master;
 370         struct nf_conn_help *master_help = nfct_help(master);
 371         struct net *net = nf_ct_exp_net(expect);
 372         struct hlist_node *n;
 373         unsigned int h;
 374         int ret;
 375
 376         NF_CT_ASSERT(master_help);
 377
 378         spin_lock_bh(&nf_conntrack_lock);
 379         if (!master_help->helper) {
 380                 ret = -ESHUTDOWN;
 381                 goto out;
 382         }
 383         h = nf_ct_expect_dst_hash(&expect->tuple);
 384         hlist_for_each_entry(i, n, &net->ct.expect_hash[h], hnode) {
 385                 if (expect_matches(i, expect)) {
 386                         /* Refresh timer: if it's dying, ignore.. */
 387                         if (refresh_timer(i)) {
 388                                 ret = 0;
 389                                 goto out;
 390                         }
 391                 } else if (expect_clash(i, expect)) {
 392                         ret = -EBUSY;
 393                         goto out;
 394                 }
 395         }
 396         /* Will be over limit? */
 397         p = &master_help->helper->expect_policy[expect->class];
 398         if (p->max_expected &&
 399             master_help->expecting[expect->class] >= p->max_expected) {
 400                 evict_oldest_expect(master, expect);
 401                 if (master_help->expecting[expect->class] >= p->max_expected) {
 402                         ret = -EMFILE;
 403                         goto out;
 404                 }
 405         }
 406
 407         if (net->ct.expect_count >= nf_ct_expect_max) {
 408                 if (net_ratelimit())
 409                         printk(KERN_WARNING
 410                                "nf_conntrack: expectation table full\n");
 411                 ret = -EMFILE;
 412                 goto out;
 413         }
 414
 415         nf_ct_expect_insert(expect);
 416         nf_ct_expect_event(IPEXP_NEW, expect);
 417         ret = 0;
 418 out:
 419         spin_unlock_bh(&nf_conntrack_lock);
 420         return ret;
 421 }
 422 EXPORT_SYMBOL_GPL(nf_ct_expect_related);
 423
 424 #ifdef CONFIG_PROC_FS
 425 struct ct_expect_iter_state {
 426         struct seq_net_private p;
 427         unsigned int bucket;
 428 };
 429
 430 static struct hlist_node *ct_expect_get_first(struct seq_file *seq)
 431 {
 432         struct net *net = seq_file_net(seq);
 433         struct ct_expect_iter_state *st = seq->private;
 434         struct hlist_node *n;
 435
 436         for (st->bucket = 0; st->bucket < nf_ct_expect_hsize; st->bucket++) {
 437                 n = rcu_dereference(net->ct.expect_hash[st->bucket].first);
 438                 if (n)
 439                         return n;
 440         }
 441         return NULL;
 442 }
 443
 444 static struct hlist_node *ct_expect_get_next(struct seq_file *seq,
 445                                              struct hlist_node *head)
 446 {
 447         struct net *net = seq_file_net(seq);
 448         struct ct_expect_iter_state *st = seq->private;
 449
 450         head = rcu_dereference(head->next);
 451         while (head == NULL) {
 452                 if (++st->bucket >= nf_ct_expect_hsize)
 453                         return NULL;
 454                 head = rcu_dereference(net->ct.expect_hash[st->bucket].first);
 455         }
 456         return head;
 457 }
 458
 459 static struct hlist_node *ct_expect_get_idx(struct seq_file *seq, loff_t pos)
 460 {
 461         struct hlist_node *head = ct_expect_get_first(seq);
 462
 463         if (head)
 464                 while (pos && (head = ct_expect_get_next(seq, head)))
 465                         pos--;
 466         return pos ? NULL : head;
 467 }
 468
 469 static void *exp_seq_start(struct seq_file *seq, loff_t *pos)
 470         __acquires(RCU)
 471 {
 472         rcu_read_lock();
 473         return ct_expect_get_idx(seq, *pos);
 474 }
 475
 476 static void *exp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 477 {
 478         (*pos)++;
 479         return ct_expect_get_next(seq, v);
 480 }
 481
 482 static void exp_seq_stop(struct seq_file *seq, void *v)
 483         __releases(RCU)
 484 {
 485         rcu_read_unlock();
 486 }
 487
 488 static int exp_seq_show(struct seq_file *s, void *v)
 489 {
 490         struct nf_conntrack_expect *expect;
 491         struct hlist_node *n = v;
 492         char *delim = "";
 493
 494         expect = hlist_entry(n, struct nf_conntrack_expect, hnode);
 495
 496         if (expect->timeout.function)
 497                 seq_printf(s, "%ld ", timer_pending(&expect->timeout)
 498                            ? (long)(expect->timeout.expires - jiffies)/HZ : 0);
 499         else
 500                 seq_printf(s, "- ");
 501         seq_printf(s, "l3proto = %u proto=%u ",
 502                    expect->tuple.src.l3num,
 503                    expect->tuple.dst.protonum);
 504         print_tuple(s, &expect->tuple,
 505                     __nf_ct_l3proto_find(expect->tuple.src.l3num),
 506                     __nf_ct_l4proto_find(expect->tuple.src.l3num,
 507                                        expect->tuple.dst.protonum));
 508
 509         if (expect->flags & NF_CT_EXPECT_PERMANENT) {
 510                 seq_printf(s, "PERMANENT");
 511                 delim = ",";
 512         }
 513         if (expect->flags & NF_CT_EXPECT_INACTIVE)
 514                 seq_printf(s, "%sINACTIVE", delim);
 515
 516         return seq_putc(s, '\n');
 517 }
 518
 519 static const struct seq_operations exp_seq_ops = {
 520         .start = exp_seq_start,
 521         .next = exp_seq_next,
 522         .stop = exp_seq_stop,
 523         .show = exp_seq_show
 524 };
 525
 526 static int exp_open(struct inode *inode, struct file *file)
 527 {
 528         return seq_open_net(inode, file, &exp_seq_ops,
 529                         sizeof(struct ct_expect_iter_state));
 530 }
 531
 532 static const struct file_operations exp_file_ops = {
 533         .owner   = THIS_MODULE,
 534         .open    = exp_open,
 535         .read    = seq_read,
 536         .llseek  = seq_lseek,
 537         .release = seq_release_net,
 538 };
 539 #endif /* CONFIG_PROC_FS */
 540
 541 static int exp_proc_init(struct net *net)
 542 {
 543 #ifdef CONFIG_PROC_FS
 544         struct proc_dir_entry *proc;
 545
 546         proc = proc_net_fops_create(net, "nf_conntrack_expect", 0440, &exp_file_ops);
 547         if (!proc)
 548                 return -ENOMEM;
 549 #endif /* CONFIG_PROC_FS */
 550         return 0;
 551 }
 552
 553 static void exp_proc_remove(struct net *net)
 554 {
 555 #ifdef CONFIG_PROC_FS
 556         proc_net_remove(net, "nf_conntrack_expect");
 557 #endif /* CONFIG_PROC_FS */
 558 }
 559
 560 module_param_named(expect_hashsize, nf_ct_expect_hsize, uint, 0600);
 561
 562 int nf_conntrack_expect_init(struct net *net)
 563 {
 564         int err = -ENOMEM;
 565
 566         if (!nf_ct_expect_hsize) {
 567                 nf_ct_expect_hsize = nf_conntrack_htable_size / 256;
 568                 if (!nf_ct_expect_hsize)
 569                         nf_ct_expect_hsize = 1;
 570         }
 571         nf_ct_expect_max = nf_ct_expect_hsize * 4;
 572
 573         net->ct.expect_count = 0;
 574         net->ct.expect_hash = nf_ct_alloc_hashtable(&nf_ct_expect_hsize,
 575                                                   &net->ct.expect_vmalloc);
 576         if (net->ct.expect_hash == NULL)
 577                 goto err1;
 578
 579         nf_ct_expect_cachep = kmem_cache_create("nf_conntrack_expect",
 580                                         sizeof(struct nf_conntrack_expect),
 581                                         0, 0, NULL);
 582         if (!nf_ct_expect_cachep)
 583                 goto err2;
 584
 585         err = exp_proc_init(net);
 586         if (err < 0)
 587                 goto err3;
 588
 589         return 0;
 590
 591 err3:
 592         kmem_cache_destroy(nf_ct_expect_cachep);
 593 err2:
 594         nf_ct_free_hashtable(net->ct.expect_hash, net->ct.expect_vmalloc,
 595                              nf_ct_expect_hsize);
 596 err1:
 597         return err;
 598 }
 599
 600 void nf_conntrack_expect_fini(struct net *net)
 601 {
 602         exp_proc_remove(net);
 603         kmem_cache_destroy(nf_ct_expect_cachep);
 604         nf_ct_free_hashtable(net->ct.expect_hash, net->ct.expect_vmalloc,
 605                              nf_ct_expect_hsize);
 606 }