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