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