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 /* Registration hooks for targets. */
  56 int
  57 xt_register_target(int af, struct xt_target *target)
  58 {
  59         int ret;
  60
  61         ret = down_interruptible(&xt[af].mutex);
  62         if (ret != 0)
  63                 return ret;
  64         list_add(&target->list, &xt[af].target);
  65         up(&xt[af].mutex);
  66         return ret;
  67 }
  68 EXPORT_SYMBOL(xt_register_target);
  69
  70 void
  71 xt_unregister_target(int af, struct xt_target *target)
  72 {
  73         down(&xt[af].mutex);
  74         LIST_DELETE(&xt[af].target, target);
  75         up(&xt[af].mutex);
  76 }
  77 EXPORT_SYMBOL(xt_unregister_target);
  78
  79 int
  80 xt_register_match(int af, struct xt_match *match)
  81 {
  82         int ret;
  83
  84         ret = down_interruptible(&xt[af].mutex);
  85         if (ret != 0)
  86                 return ret;
  87
  88         list_add(&match->list, &xt[af].match);
  89         up(&xt[af].mutex);
  90
  91         return ret;
  92 }
  93 EXPORT_SYMBOL(xt_register_match);
  94
  95 void
  96 xt_unregister_match(int af, struct xt_match *match)
  97 {
  98         down(&xt[af].mutex);
  99         LIST_DELETE(&xt[af].match, match);
 100         up(&xt[af].mutex);
 101 }
 102 EXPORT_SYMBOL(xt_unregister_match);
 103
 104
 105 /*
 106  * These are weird, but module loading must not be done with mutex
 107  * held (since they will register), and we have to have a single
 108  * function to use try_then_request_module().
 109  */
 110
 111 /* Find match, grabs ref.  Returns ERR_PTR() on error. */
 112 struct xt_match *xt_find_match(int af, const char *name, u8 revision)
 113 {
 114         struct xt_match *m;
 115         int err = 0;
 116
 117         if (down_interruptible(&xt[af].mutex) != 0)
 118                 return ERR_PTR(-EINTR);
 119
 120         list_for_each_entry(m, &xt[af].match, list) {
 121                 if (strcmp(m->name, name) == 0) {
 122                         if (m->revision == revision) {
 123                                 if (try_module_get(m->me)) {
 124                                         up(&xt[af].mutex);
 125                                         return m;
 126                                 }
 127                         } else
 128                                 err = -EPROTOTYPE; /* Found something. */
 129                 }
 130         }
 131         up(&xt[af].mutex);
 132         return ERR_PTR(err);
 133 }
 134 EXPORT_SYMBOL(xt_find_match);
 135
 136 /* Find target, grabs ref.  Returns ERR_PTR() on error. */
 137 struct xt_target *xt_find_target(int af, const char *name, u8 revision)
 138 {
 139         struct xt_target *t;
 140         int err = 0;
 141
 142         if (down_interruptible(&xt[af].mutex) != 0)
 143                 return ERR_PTR(-EINTR);
 144
 145         list_for_each_entry(t, &xt[af].target, list) {
 146                 if (strcmp(t->name, name) == 0) {
 147                         if (t->revision == revision) {
 148                                 if (try_module_get(t->me)) {
 149                                         up(&xt[af].mutex);
 150                                         return t;
 151                                 }
 152                         } else
 153                                 err = -EPROTOTYPE; /* Found something. */
 154                 }
 155         }
 156         up(&xt[af].mutex);
 157         return ERR_PTR(err);
 158 }
 159 EXPORT_SYMBOL(xt_find_target);
 160
 161 static const char *xt_prefix[NPROTO] = {
 162         [AF_INET]       = "ipt_%s",
 163         [AF_INET6]      = "ip6t_%s",
 164         [NF_ARP]        = "arpt_%s",
 165 };
 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                                          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 struct xt_table_info *xt_alloc_table_info(unsigned int size)
 241 {
 242         struct xt_table_info *newinfo;
 243         int cpu;
 244
 245         /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
 246         if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > num_physpages)
 247                 return NULL;
 248
 249         newinfo = kzalloc(sizeof(struct xt_table_info), GFP_KERNEL);
 250         if (!newinfo)
 251                 return NULL;
 252
 253         newinfo->size = size;
 254
 255         for_each_cpu(cpu) {
 256                 if (size <= PAGE_SIZE)
 257                         newinfo->entries[cpu] = kmalloc_node(size,
 258                                                         GFP_KERNEL,
 259                                                         cpu_to_node(cpu));
 260                 else
 261                         newinfo->entries[cpu] = vmalloc_node(size,
 262                                                         cpu_to_node(cpu));
 263
 264                 if (newinfo->entries[cpu] == NULL) {
 265                         xt_free_table_info(newinfo);
 266                         return NULL;
 267                 }
 268         }
 269
 270         return newinfo;
 271 }
 272 EXPORT_SYMBOL(xt_alloc_table_info);
 273
 274 void xt_free_table_info(struct xt_table_info *info)
 275 {
 276         int cpu;
 277
 278         for_each_cpu(cpu) {
 279                 if (info->size <= PAGE_SIZE)
 280                         kfree(info->entries[cpu]);
 281                 else
 282                         vfree(info->entries[cpu]);
 283         }
 284         kfree(info);
 285 }
 286 EXPORT_SYMBOL(xt_free_table_info);
 287
 288 /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
 289 struct xt_table *xt_find_table_lock(int af, const char *name)
 290 {
 291         struct xt_table *t;
 292
 293         if (down_interruptible(&xt[af].mutex) != 0)
 294                 return ERR_PTR(-EINTR);
 295
 296         list_for_each_entry(t, &xt[af].tables, list)
 297                 if (strcmp(t->name, name) == 0 && try_module_get(t->me))
 298                         return t;
 299         up(&xt[af].mutex);
 300         return NULL;
 301 }
 302 EXPORT_SYMBOL_GPL(xt_find_table_lock);
 303
 304 void xt_table_unlock(struct xt_table *table)
 305 {
 306         up(&xt[table->af].mutex);
 307 }
 308 EXPORT_SYMBOL_GPL(xt_table_unlock);
 309
 310
 311 struct xt_table_info *
 312 xt_replace_table(struct xt_table *table,
 313               unsigned int num_counters,
 314               struct xt_table_info *newinfo,
 315               int *error)
 316 {
 317         struct xt_table_info *oldinfo, *private;
 318
 319         /* Do the substitution. */
 320         write_lock_bh(&table->lock);
 321         private = table->private;
 322         /* Check inside lock: is the old number correct? */
 323         if (num_counters != private->number) {
 324                 duprintf("num_counters != table->private->number (%u/%u)\n",
 325                          num_counters, private->number);
 326                 write_unlock_bh(&table->lock);
 327                 *error = -EAGAIN;
 328                 return NULL;
 329         }
 330         oldinfo = private;
 331         table->private = newinfo;
 332         newinfo->initial_entries = oldinfo->initial_entries;
 333         write_unlock_bh(&table->lock);
 334
 335         return oldinfo;
 336 }
 337 EXPORT_SYMBOL_GPL(xt_replace_table);
 338
 339 int xt_register_table(struct xt_table *table,
 340                       struct xt_table_info *bootstrap,
 341                       struct xt_table_info *newinfo)
 342 {
 343         int ret;
 344         struct xt_table_info *private;
 345
 346         ret = down_interruptible(&xt[table->af].mutex);
 347         if (ret != 0)
 348                 return ret;
 349
 350         /* Don't autoload: we'd eat our tail... */
 351         if (list_named_find(&xt[table->af].tables, table->name)) {
 352                 ret = -EEXIST;
 353                 goto unlock;
 354         }
 355
 356         /* Simplifies replace_table code. */
 357         table->private = bootstrap;
 358         if (!xt_replace_table(table, 0, newinfo, &ret))
 359                 goto unlock;
 360
 361         private = table->private;
 362         duprintf("table->private->number = %u\n", private->number);
 363
 364         /* save number of initial entries */
 365         private->initial_entries = private->number;
 366
 367         rwlock_init(&table->lock);
 368         list_prepend(&xt[table->af].tables, table);
 369
 370         ret = 0;
 371  unlock:
 372         up(&xt[table->af].mutex);
 373         return ret;
 374 }
 375 EXPORT_SYMBOL_GPL(xt_register_table);
 376
 377 void *xt_unregister_table(struct xt_table *table)
 378 {
 379         struct xt_table_info *private;
 380
 381         down(&xt[table->af].mutex);
 382         private = table->private;
 383         LIST_DELETE(&xt[table->af].tables, table);
 384         up(&xt[table->af].mutex);
 385
 386         return private;
 387 }
 388 EXPORT_SYMBOL_GPL(xt_unregister_table);
 389
 390 #ifdef CONFIG_PROC_FS
 391 static char *xt_proto_prefix[NPROTO] = {
 392         [AF_INET]       = "ip",
 393         [AF_INET6]      = "ip6",
 394         [NF_ARP]        = "arp",
 395 };
 396
 397 static struct list_head *xt_get_idx(struct list_head *list, struct seq_file *seq, loff_t pos)
 398 {
 399         struct list_head *head = list->next;
 400
 401         if (!head || list_empty(list))
 402                 return NULL;
 403
 404         while (pos && (head = head->next)) {
 405                 if (head == list)
 406                         return NULL;
 407                 pos--;
 408         }
 409         return pos ? NULL : head;
 410 }
 411
 412 static struct list_head *type2list(u_int16_t af, u_int16_t type)
 413 {
 414         struct list_head *list;
 415
 416         switch (type) {
 417         case TARGET:
 418                 list = &xt[af].target;
 419                 break;
 420         case MATCH:
 421                 list = &xt[af].match;
 422                 break;
 423         case TABLE:
 424                 list = &xt[af].tables;
 425                 break;
 426         default:
 427                 list = NULL;
 428                 break;
 429         }
 430
 431         return list;
 432 }
 433
 434 static void *xt_tgt_seq_start(struct seq_file *seq, loff_t *pos)
 435 {
 436         struct proc_dir_entry *pde = (struct proc_dir_entry *) seq->private;
 437         u_int16_t af = (unsigned long)pde->data & 0xffff;
 438         u_int16_t type = (unsigned long)pde->data >> 16;
 439         struct list_head *list;
 440
 441         if (af >= NPROTO)
 442                 return NULL;
 443
 444         list = type2list(af, type);
 445         if (!list)
 446                 return NULL;
 447
 448         if (down_interruptible(&xt[af].mutex) != 0)
 449                 return NULL;
 450
 451         return xt_get_idx(list, seq, *pos);
 452 }
 453
 454 static void *xt_tgt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 455 {
 456         struct proc_dir_entry *pde = seq->private;
 457         u_int16_t af = (unsigned long)pde->data & 0xffff;
 458         u_int16_t type = (unsigned long)pde->data >> 16;
 459         struct list_head *list;
 460
 461         if (af >= NPROTO)
 462                 return NULL;
 463
 464         list = type2list(af, type);
 465         if (!list)
 466                 return NULL;
 467
 468         (*pos)++;
 469         return xt_get_idx(list, seq, *pos);
 470 }
 471
 472 static void xt_tgt_seq_stop(struct seq_file *seq, void *v)
 473 {
 474         struct proc_dir_entry *pde = seq->private;
 475         u_int16_t af = (unsigned long)pde->data & 0xffff;
 476
 477         up(&xt[af].mutex);
 478 }
 479
 480 static int xt_name_seq_show(struct seq_file *seq, void *v)
 481 {
 482         char *name = (char *)v + sizeof(struct list_head);
 483
 484         if (strlen(name))
 485                 return seq_printf(seq, "%s\n", name);
 486         else
 487                 return 0;
 488 }
 489
 490 static struct seq_operations xt_tgt_seq_ops = {
 491         .start  = xt_tgt_seq_start,
 492         .next   = xt_tgt_seq_next,
 493         .stop   = xt_tgt_seq_stop,
 494         .show   = xt_name_seq_show,
 495 };
 496
 497 static int xt_tgt_open(struct inode *inode, struct file *file)
 498 {
 499         int ret;
 500
 501         ret = seq_open(file, &xt_tgt_seq_ops);
 502         if (!ret) {
 503                 struct seq_file *seq = file->private_data;
 504                 struct proc_dir_entry *pde = PDE(inode);
 505
 506                 seq->private = pde;
 507         }
 508
 509         return ret;
 510 }
 511
 512 static struct file_operations xt_file_ops = {
 513         .owner   = THIS_MODULE,
 514         .open    = xt_tgt_open,
 515         .read    = seq_read,
 516         .llseek  = seq_lseek,
 517         .release = seq_release,
 518 };
 519
 520 #define FORMAT_TABLES   "_tables_names"
 521 #define FORMAT_MATCHES  "_tables_matches"
 522 #define FORMAT_TARGETS  "_tables_targets"
 523
 524 #endif /* CONFIG_PROC_FS */
 525
 526 int xt_proto_init(int af)
 527 {
 528 #ifdef CONFIG_PROC_FS
 529         char buf[XT_FUNCTION_MAXNAMELEN];
 530         struct proc_dir_entry *proc;
 531 #endif
 532
 533         if (af >= NPROTO)
 534                 return -EINVAL;
 535
 536
 537 #ifdef CONFIG_PROC_FS
 538         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 539         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 540         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 541         if (!proc)
 542                 goto out;
 543         proc->data = (void *) ((unsigned long) af | (TABLE << 16));
 544
 545
 546         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 547         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 548         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 549         if (!proc)
 550                 goto out_remove_tables;
 551         proc->data = (void *) ((unsigned long) af | (MATCH << 16));
 552
 553         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 554         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
 555         proc = proc_net_fops_create(buf, 0440, &xt_file_ops);
 556         if (!proc)
 557                 goto out_remove_matches;
 558         proc->data = (void *) ((unsigned long) af | (TARGET << 16));
 559 #endif
 560
 561         return 0;
 562
 563 #ifdef CONFIG_PROC_FS
 564 out_remove_matches:
 565         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 566         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 567         proc_net_remove(buf);
 568
 569 out_remove_tables:
 570         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 571         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 572         proc_net_remove(buf);
 573 out:
 574         return -1;
 575 #endif
 576 }
 577 EXPORT_SYMBOL_GPL(xt_proto_init);
 578
 579 void xt_proto_fini(int af)
 580 {
 581 #ifdef CONFIG_PROC_FS
 582         char buf[XT_FUNCTION_MAXNAMELEN];
 583
 584         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 585         strlcat(buf, FORMAT_TABLES, sizeof(buf));
 586         proc_net_remove(buf);
 587
 588         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 589         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
 590         proc_net_remove(buf);
 591
 592         strlcpy(buf, xt_proto_prefix[af], sizeof(buf));
 593         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
 594         proc_net_remove(buf);
 595 #endif /*CONFIG_PROC_FS*/
 596 }
 597 EXPORT_SYMBOL_GPL(xt_proto_fini);
 598
 599
 600 static int __init xt_init(void)
 601 {
 602         int i;
 603
 604         xt = kmalloc(sizeof(struct xt_af) * NPROTO, GFP_KERNEL);
 605         if (!xt)
 606                 return -ENOMEM;
 607
 608         for (i = 0; i < NPROTO; i++) {
 609                 init_MUTEX(&xt[i].mutex);
 610                 INIT_LIST_HEAD(&xt[i].target);
 611                 INIT_LIST_HEAD(&xt[i].match);
 612                 INIT_LIST_HEAD(&xt[i].tables);
 613         }
 614         return 0;
 615 }
 616
 617 static void __exit xt_fini(void)
 618 {
 619         kfree(xt);
 620 }
 621
 622 module_init(xt_init);
 623 module_exit(xt_fini);
 624