net/netfilter/x_tables.c

   1 /*
   2  * x_tables core - Backend for {ip,ip6,arp}_tables
   3  *
   4  * Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>
   5  *
   6  * Based on existing ip_tables code which is
   7  *   Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   8  *   Copyright (C) 2000-2005 Netfilter Core Team <coreteam@netfilter.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/kernel.h>
  18 #include <linux/socket.h>
  19 #include <linux/net.h>
  20 #include <linux/proc_fs.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/string.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/mutex.h>
  25
  26 #include <linux/netfilter/x_tables.h>
  27 #include <linux/netfilter_arp.h>
  28
  29
  30 MODULE_LICENSE("GPL");
  31 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  32 MODULE_DESCRIPTION("[ip,ip6,arp]_tables backend module");
  33
  34 #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
  35
  36 struct xt_af {
  37         struct mutex mutex;
  38         struct list_head match;
  39         struct list_head target;
  40         struct list_head tables;
  41 };
  42
  43 static struct xt_af *xt;
  44
  45 #ifdef DEBUG_IP_FIREWALL_USER
  46 #define duprintf(format, args...) printk(format , ## args)
  47 #else
  48 #define duprintf(format, args...)
  49 #endif
  50
  51 enum {
  52         TABLE,
  53         TARGET,
  54         MATCH,
  55 };
  56
  57 static const char *xt_prefix[NPROTO] = {
  58         [AF_INET]       = "ip",
  59         [AF_INET6]      = "ip6",
  60         [NF_ARP]        = "arp",
  61 };
  62
  63 /* Registration hooks for targets. */
  64 int
  65 xt_register_target(struct xt_target *target)
  66 {
  67         int ret, af = target->family;
  68
  69         ret = mutex_lock_interruptible(&xt[af].mutex);
  70         if (ret != 0)
  71                 return ret;
  72         list_add(&target->list, &xt[af].target);
  73         mutex_unlock(&xt[af].mutex);
  74         return ret;
  75 }
  76 EXPORT_SYMBOL(xt_register_target);
  77
  78 void
  79 xt_unregister_target(struct xt_target *target)
  80 {
  81         int af = target->family;
  82
  83         mutex_lock(&xt[af].mutex);
  84         LIST_DELETE(&xt[af].target, target);
  85         mutex_unlock(&xt[af].mutex);
  86 }
  87 EXPORT_SYMBOL(xt_unregister_target);
  88
  89 int
  90 xt_register_match(struct xt_match *match)
  91 {
  92         int ret, af = match->family;
  93
  94         ret = mutex_lock_interruptible(&xt[af].mutex);
  95         if (ret != 0)
  96                 return ret;
  97
  98         list_add(&match->list, &xt[af].match);
  99         mutex_unlock(&xt[af].mutex);
 100
 101         return ret;
 102 }
 103 EXPORT_SYMBOL(xt_register_match);
 104
 105 void
 106 xt_unregister_match(struct xt_match *match)
 107 {
 108         int af =  match->family;
 109
 110         mutex_lock(&xt[af].mutex);
 111         LIST_DELETE(&xt[af].match, match);
 112         mutex_unlock(&xt[af].mutex);
 113 }
 114 EXPORT_SYMBOL(xt_unregister_match);
 115
 116
 117 /*
 118  * These are weird, but module loading must not be done with mutex
 119  * held (since they will register), and we have to have a single
 120  * function to use try_then_request_module().
 121  */
 122
 123 /* Find match, grabs ref.  Returns ERR_PTR() on error. */
 124 struct xt_match *xt_find_match(int af, const char *name, u8 revision)
 125 {
 126         struct xt_match *m;
 127         int err = 0;
 128
 129         if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 130                 return ERR_PTR(-EINTR);
 131
 132         list_for_each_entry(m, &xt[af].match, list) {
 133                 if (strcmp(m->name, name) == 0) {
 134                         if (m->revision == revision) {
 135                                 if (try_module_get(m->me)) {
 136                                         mutex_unlock(&xt[af].mutex);
 137                                         return m;
 138                                 }
 139                         } else
 140                                 err = -EPROTOTYPE; /* Found something. */
 141                 }
 142         }
 143         mutex_unlock(&xt[af].mutex);
 144         return ERR_PTR(err);
 145 }
 146 EXPORT_SYMBOL(xt_find_match);
 147
 148 /* Find target, grabs ref.  Returns ERR_PTR() on error. */
 149 struct xt_target *xt_find_target(int af, const char *name, u8 revision)
 150 {
 151         struct xt_target *t;
 152         int err = 0;
 153
 154         if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 155                 return ERR_PTR(-EINTR);
 156
 157         list_for_each_entry(t, &xt[af].target, list) {
 158                 if (strcmp(t->name, name) == 0) {
 159                         if (t->revision == revision) {
 160                                 if (try_module_get(t->me)) {
 161                                         mutex_unlock(&xt[af].mutex);
 162                                         return t;
 163                                 }
 164                         } else
 165                                 err = -EPROTOTYPE; /* Found something. */
 166                 }
 167         }
 168         mutex_unlock(&xt[af].mutex);
 169         return ERR_PTR(err);
 170 }
 171 EXPORT_SYMBOL(xt_find_target);
 172
 173 struct xt_target *xt_request_find_target(int af, const char *name, u8 revision)
 174 {
 175         struct xt_target *target;
 176
 177         target = try_then_request_module(xt_find_target(af, name, revision),
 178                                          "%st_%s", xt_prefix[af], name);
 179         if (IS_ERR(target) || !target)
 180                 return NULL;
 181         return target;
 182 }
 183 EXPORT_SYMBOL_GPL(xt_request_find_target);
 184
 185 static int match_revfn(int af, const char *name, u8 revision, int *bestp)
 186 {
 187         struct xt_match *m;
 188         int have_rev = 0;
 189
 190         list_for_each_entry(m, &xt[af].match, list) {
 191                 if (strcmp(m->name, name) == 0) {
 192                         if (m->revision > *bestp)
 193                                 *bestp = m->revision;
 194                         if (m->revision == revision)
 195                                 have_rev = 1;
 196                 }
 197         }
 198         return have_rev;
 199 }
 200
 201 static int target_revfn(int af, const char *name, u8 revision, int *bestp)
 202 {
 203         struct xt_target *t;
 204         int have_rev = 0;
 205
 206         list_for_each_entry(t, &xt[af].target, list) {
 207                 if (strcmp(t->name, name) == 0) {
 208                         if (t->revision > *bestp)
 209                                 *bestp = t->revision;
 210                         if (t->revision == revision)
 211                                 have_rev = 1;
 212                 }
 213         }
 214         return have_rev;
 215 }
 216
 217 /* Returns true or false (if no such extension at all) */
 218 int xt_find_revision(int af, const char *name, u8 revision, int target,
 219                      int *err)
 220 {
 221         int have_rev, best = -1;
 222
 223         if (mutex_lock_interruptible(&xt[af].mutex) != 0) {
 224                 *err = -EINTR;
 225                 return 1;
 226         }
 227         if (target == 1)
 228                 have_rev = target_revfn(af, name, revision, &best);
 229         else
 230                 have_rev = match_revfn(af, name, revision, &best);
 231         mutex_unlock(&xt[af].mutex);
 232
 233         /* Nothing at all?  Return 0 to try loading module. */
 234         if (best == -1) {
 235                 *err = -ENOENT;
 236                 return 0;
 237         }
 238
 239         *err = best;
 240         if (!have_rev)
 241                 *err = -EPROTONOSUPPORT;
 242         return 1;
 243 }
 244 EXPORT_SYMBOL_GPL(xt_find_revision);
 245
 246 int xt_check_match(const struct xt_match *match, unsigned short family,
 247                    unsigned int size, const char *table, unsigned int hook_mask,
 248                    unsigned short proto, int inv_proto)
 249 {
 250         if (XT_ALIGN(match->matchsize) != size) {
 251                 printk("%s_tables: %s match: invalid size %Zu != %u\n",
 252                        xt_prefix[family], match->name,
 253                        XT_ALIGN(match->matchsize), size);
 254                 return -EINVAL;
 255         }
 256         if (match->table && strcmp(match->table, table)) {
 257                 printk("%s_tables: %s match: only valid in %s table, not %s\n",
 258                        xt_prefix[family], match->name, match->table, table);
 259                 return -EINVAL;
 260         }
 261         if (match->hooks && (hook_mask & ~match->hooks) != 0) {
 262                 printk("%s_tables: %s match: bad hook_mask %u\n",
 263                        xt_prefix[family], match->name, hook_mask);
 264                 return -EINVAL;
 265         }
 266         if (match->proto && (match->proto != proto || inv_proto)) {
 267                 printk("%s_tables: %s match: only valid for protocol %u\n",
 268                        xt_prefix[family], match->name, match->proto);
 269                 return -EINVAL;
 270         }
 271         return 0;
 272 }
 273 EXPORT_SYMBOL_GPL(xt_check_match);
 274
 275 int xt_check_target(const struct xt_target *target, unsigned short family,
 276                     unsigned int size, const char *table, unsigned int hook_mask,
 277                     unsigned short proto, int inv_proto)
 278 {
 279         if (XT_ALIGN(target->targetsize) != size) {
 280                 printk("%s_tables: %s target: invalid size %Zu != %u\n",
 281                        xt_prefix[family], target->name,
 282                        XT_ALIGN(target->targetsize), size);
 283                 return -EINVAL;
 284         }
 285         if (target->table && strcmp(target->table, table)) {
 286                 printk("%s_tables: %s target: only valid in %s table, not %s\n",
 287                        xt_prefix[family], target->name, target->table, table);
 288                 return -EINVAL;
 289         }
 290         if (target->hooks && (hook_mask & ~target->hooks) != 0) {
 291                 printk("%s_tables: %s target: bad hook_mask %u\n",
 292                        xt_prefix[family], target->name, hook_mask);
 293                 return -EINVAL;
 294         }
 295         if (target->proto && (target->proto != proto || inv_proto)) {
 296                 printk("%s_tables: %s target: only valid for protocol %u\n",
 297                        xt_prefix[family], target->name, target->proto);
 298                 return -EINVAL;
 299         }
 300         return 0;
 301 }
 302 EXPORT_SYMBOL_GPL(xt_check_target);
 303
 304 struct xt_table_info *xt_alloc_table_info(unsigned int size)
 305 {
 306         struct xt_table_info *newinfo;
 307         int cpu;
 308
 309         /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
 310         if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > num_physpages)
 311                 return NULL;
 312
 313         newinfo = kzalloc(sizeof(struct xt_table_info), GFP_KERNEL);
 314         if (!newinfo)
 315                 return NULL;
 316
 317         newinfo->size = size;
 318
 319         for_each_cpu(cpu) {
 320                 if (size <= PAGE_SIZE)
 321                         newinfo->entries[cpu] = kmalloc_node(size,
 322                                                         GFP_KERNEL,
 323                                                         cpu_to_node(cpu));
 324                 else
 325                         newinfo->entries[cpu] = vmalloc_node(size,
 326                                                         cpu_to_node(cpu));
 327
 328                 if (newinfo->entries[cpu] == NULL) {
 329                         xt_free_table_info(newinfo);
 330                         return NULL;
 331                 }
 332         }
 333
 334         return newinfo;
 335 }
 336 EXPORT_SYMBOL(xt_alloc_table_info);
 337
 338 void xt_free_table_info(struct xt_table_info *info)
 339 {
 340         int cpu;
 341
 342         for_each_cpu(cpu) {
 343                 if (info->size <= PAGE_SIZE)
 344                         kfree(info->entries[cpu]);
 345                 else
 346                         vfree(info->entries[cpu]);
 347         }
 348         kfree(info);
 349 }
 350 EXPORT_SYMBOL(xt_free_table_info);
 351
 352 /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
 353 struct xt_table *xt_find_table_lock(int af, const char *name)
 354 {
 355         struct xt_table *t;
 356
 357         if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 358                 return ERR_PTR(-EINTR);
 359
 360         list_for_each_entry(t, &xt[af].tables, list)
 361                 if (strcmp(t->name, name) == 0 && try_module_get(t->me))
 362                         return t;
 363         mutex_unlock(&xt[af].mutex);
 364         return NULL;
 365 }
 366 EXPORT_SYMBOL_GPL(xt_find_table_lock);
 367
 368 void xt_table_unlock(struct xt_table *table)
 369 {
 370         mutex_unlock(&xt[table->af].mutex);
 371 }
 372 EXPORT_SYMBOL_GPL(xt_table_unlock);
 373
 374
 375 struct xt_table_info *
 376 xt_replace_table(struct xt_table *table,
 377               unsigned int num_counters,
 378               struct xt_table_info *newinfo,
 379               int *error)
 380 {
 381         struct xt_table_info *oldinfo, *private;
 382
 383         /* Do the substitution. */
 384         write_lock_bh(&table->lock);
 385         private = table->private;
 386         /* Check inside lock: is the old number correct? */
 387         if (num_counters != private->number) {
 388                 duprintf("num_counters != table->private->number (%u/%u)\n",
 389                          num_counters, private->number);
 390                 write_unlock_bh(&table->lock);
 391                 *error = -EAGAIN;
 392                 return NULL;
 393         }
 394         oldinfo = private;
 395         table->private = newinfo;
 396         newinfo->initial_entries = oldinfo->initial_entries;
 397         write_unlock_bh(&table->lock);
 398
 399         return oldinfo;
 400 }
 401 EXPORT_SYMBOL_GPL(xt_replace_table);
 402
 403 int xt_register_table(struct xt_table *table,
 404                       struct xt_table_info *bootstrap,
 405                       struct xt_table_info *newinfo)
 406 {
 407         int ret;
 408         struct xt_table_info *private;
 409
 410         ret = mutex_lock_interruptible(&xt[table->af].mutex);
 411         if (ret != 0)
 412                 return ret;
 413
 414         /* Don't autoload: we'd eat our tail... */
 415         if (list_named_find(&xt[table->af].tables, table->name)) {
 416                 ret = -EEXIST;
 417                 goto unlock;
 418         }
 419
 420         /* Simplifies replace_table code. */
 421         table->private = bootstrap;
 422         if (!xt_replace_table(table, 0, newinfo, &ret))
 423                 goto unlock;
 424
 425         private = table->private;
 426         duprintf("table->private->number = %u\n", private->number);
 427
 428         /* save number of initial entries */
 429         private->initial_entries = private->number;
 430
 431         rwlock_init(&table->lock);
 432         list_prepend(&xt[table->af].tables, table);
 433
 434         ret = 0;
 435  unlock:
 436         mutex_unlock(&xt[table->af].mutex);
 437         return ret;
 438 }
 439 EXPORT_SYMBOL_GPL(xt_register_table);
 440
 441 void *xt_unregister_table(struct xt_table *table)
 442 {
 443         struct xt_table_info *private;
 444
 445         mutex_lock(&xt[table->af].mutex);
 446         private = table->private;
 447         LIST_DELETE(&xt[table->af].tables, table);
 448         mutex_unlock(&xt[table->af].mutex);
 449
 450         return private;
 451 }
 452 EXPORT_SYMBOL_GPL(xt_unregister_table);
 453
 454 #ifdef CONFIG_PROC_FS
 455 static char *xt_proto_prefix[NPROTO] = {
 456         [AF_INET]       = "ip",
 457         [AF_INET6]      = "ip6",
 458         [NF_ARP]        = "arp",
 459 };
 460
 461 static struct list_head *xt_get_idx(struct list_head *list, struct seq_file *seq, loff_t pos)
 462 {
 463         struct list_head *head = list->next;
 464
 465         if (!head || list_empty(list))
 466                 return NULL;
 467
 468         while (pos && (head = head->next)) {
 469                 if (head == list)
 470                         return NULL;
 471                 pos--;
 472         }
 473         return pos ? NULL : head;
 474 }
 475
 476 static struct list_head *type2list(u_int16_t af, u_int16_t type)
 477 {
 478         struct list_head *list;
 479
 480         switch (type) {
 481         case TARGET:
 482                 list = &xt[af].target;
 483                 break;
 484         case MATCH:
 485                 list = &xt[af].match;
 486                 break;
 487         case TABLE:
 488                 list = &xt[af].tables;
 489                 break;
 490         default:
 491                 list = NULL;
 492                 break;
 493         }
 494
 495         return list;
 496 }
 497
 498 static void *xt_tgt_seq_start(struct seq_file *seq, loff_t *pos)
 499 {
 500         struct proc_dir_entry *pde = (struct proc_dir_entry *) seq->private;
 501         u_int16_t af = (unsigned long)pde->data & 0xffff;
 502         u_int16_t type = (unsigned long)pde->data >> 16;
 503         struct list_head *list;
 504
 505         if (af >= NPROTO)
 506                 return NULL;
 507
 508         list = type2list(af, type);
 509         if (!list)
 510                 return NULL;
 511
 512         if (mutex_lock_interruptible(&xt[af].mutex) != 0)
 513                 return NULL;
 514
 515         return xt_get_idx(list, seq, *pos);
 516 }
 517
 518 static void *xt_tgt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 519 {
 520         struct proc_dir_entry *pde = seq->private;
 521         u_int16_t af = (unsigned long)pde->data & 0xffff;
 522         u_int16_t type = (unsigned long)pde->data >> 16;
 523         struct list_head *list;
 524
 525         if (af >= NPROTO)
 526                 return NULL;
 527
 528         list = type2list(af, type);
 529         if (!list)
 530                 return NULL;
 531
 532         (*pos)++;
 533         return xt_get_idx(list, seq, *pos);
 534 }
 535
 536 static void xt_tgt_seq_stop(struct seq_file *seq, void *v)
 537 {
 538         struct proc_dir_entry *pde = seq->private;
 539         u_int16_t af = (unsigned long)pde->data & 0xffff;
 540
 541         mutex_unlock(&xt[af].mutex);
 542 }
 543
 544 static int xt_name_seq_show(struct seq_file *seq, void *v)
 545 {
 546         char *name = (char *)v + sizeof(struct list_head);
 547
 548         if (strlen(name))
 549                 return seq_printf(seq, "%s\n", name);
 550         else
 551                 return 0;
 552 }
 553
 554 static struct seq_operations xt_tgt_seq_ops = {
 555         .start  = xt_tgt_seq_start,
 556         .next   = xt_tgt_seq_next,
 557         .stop   = xt_tgt_seq_stop,
 558         .show   = xt_name_seq_show,
 559 };
 560
 561 static int xt_tgt_open(struct inode *inode, struct file *file)
 562 {
 563         int ret;
 564
 565         ret = seq_open(file, &xt_tgt_seq_ops);
 566         if (!ret) {
 567                 struct seq_file *seq = file->private_data;
 568                 struct proc_dir_entry *pde = PDE(inode);
 569
 570                 seq->private = pde;
 571         }
 572
 573         return ret;
 574 }
 575
 576 static struct file_operations xt_file_ops = {
 577         .owner   = THIS_MODULE,
 578         .open    = xt_tgt_open,
 579         .read    = seq_read,
 580         .llseek  = seq_lseek,
 581         .release = seq_release,
 582 };
 583
 584 #define FORMAT_TABLES   "_tables_names"
 585 #define FORMAT_MATCHES  "_tables_matches"
 586 #define FORMAT_TARGETS  "_tables_targets"
 587
 588 #endif /* CONFIG_PROC_FS */
 589
 590 int xt_proto_init(int af)
 591 {
 592 #ifdef CONFIG_PROC_FS
 593         char buf[XT_FUNCTION_MAXNAMELEN];
 594         struct proc_dir_entry *proc;
 595 #endif
 596
 597         if (af >= NPROTO)
 598                 return -EINVAL;
 599
 600
 601 #ifdef CONFIG_PROC_FS
 602         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 603         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 604         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 605         if (!proc)
 606                 goto out;
 607         proc->data = (void *) ((unsigned long) af | (TABLE << 16));
 608
 609
 610         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 611         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 612         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 613         if (!proc)
 614                 goto out_remove_tables;
 615         proc->data = (void *) ((unsigned long) af | (MATCH << 16));
 616
 617         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 618         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
 619         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 620         if (!proc)
 621                 goto out_remove_matches;
 622         proc->data = (void *) ((unsigned long) af | (TARGET << 16));
 623 #endif
 624
 625         return 0;
 626
 627 #ifdef CONFIG_PROC_FS
 628 out_remove_matches:
 629         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 630         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 631         proc_net_remove(buf);
 632
 633 out_remove_tables:
 634         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 635         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 636         proc_net_remove(buf);
 637 out:
 638         return -1;
 639 #endif
 640 }
 641 EXPORT_SYMBOL_GPL(xt_proto_init);
 642
 643 void xt_proto_fini(int af)
 644 {
 645 #ifdef CONFIG_PROC_FS
 646         char buf[XT_FUNCTION_MAXNAMELEN];
 647
 648         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 649         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 650         proc_net_remove(buf);
 651
 652         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 653         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
 654         proc_net_remove(buf);
 655
 656         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 657         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 658         proc_net_remove(buf);
 659 #endif /*CONFIG_PROC_FS*/
 660 }
 661 EXPORT_SYMBOL_GPL(xt_proto_fini);
 662
 663
 664 static int __init xt_init(void)
 665 {
 666         int i;
 667
 668         xt = kmalloc(sizeof(struct xt_af) * NPROTO, GFP_KERNEL);
 669         if (!xt)
 670                 return -ENOMEM;
 671
 672         for (i = 0; i < NPROTO; i++) {
 673                 mutex_init(&xt[i].mutex);
 674                 INIT_LIST_HEAD(&xt[i].target);
 675                 INIT_LIST_HEAD(&xt[i].match);
 676                 INIT_LIST_HEAD(&xt[i].tables);
 677         }
 678         return 0;
 679 }
 680
 681 static void __exit xt_fini(void)
 682 {
 683         kfree(xt);
 684 }
 685
 686 module_init(xt_init);
 687 module_exit(xt_fini);
 688