1 /* Library which manipulates firewall rules. Version 0.1. */ 2 3 /* Architecture of firewall rules is as follows: 4 * 5 * Chains go INPUT, FORWARD, OUTPUT then user chains. 6 * Each user chain starts with an ERROR node. 7 * Every chain ends with an unconditional jump: a RETURN for user chains, 8 * and a POLICY for built-ins. 9 */ 10 11 /* (C)1999 Paul ``Rusty'' Russell - Placed under the GNU GPL (See 12 COPYING for details). */ 13 14 #include <assert.h> 15 #include <string.h> 16 #include <errno.h> 17 #include <stdlib.h> 18 #include <stdio.h> 19 #include <unistd.h> 20 #include <netinet/in.h> 21 22 #ifdef DEBUG_CONNTRACK 23 #define inline 24 #endif 25 26 #include "libiptc/libiptc.h" 27 28 #define IP_VERSION 4 29 #define IP_OFFSET 0x1FFF 30 31 #define HOOK_PRE_ROUTING NF_IP_PRE_ROUTING 32 #define HOOK_LOCAL_IN NF_IP_LOCAL_IN 33 #define HOOK_FORWARD NF_IP_FORWARD 34 #define HOOK_LOCAL_OUT NF_IP_LOCAL_OUT 35 #define HOOK_POST_ROUTING NF_IP_POST_ROUTING 36 #ifdef NF_IP_DROPPING 37 #define HOOK_DROPPING NF_IP_DROPPING 38 #endif 39 40 #define STRUCT_ENTRY_TARGET struct ipt_entry_target 41 #define STRUCT_ENTRY struct ipt_entry 42 #define STRUCT_ENTRY_MATCH struct ipt_entry_match 43 #define STRUCT_GETINFO struct ipt_getinfo 44 #define STRUCT_GET_ENTRIES struct ipt_get_entries 45 #define STRUCT_COUNTERS struct ipt_counters 46 #define STRUCT_COUNTERS_INFO struct ipt_counters_info 47 #define STRUCT_STANDARD_TARGET struct ipt_standard_target 48 #define STRUCT_REPLACE struct ipt_replace 49 50 #define STRUCT_TC_HANDLE struct iptc_handle 51 #define TC_HANDLE_T iptc_handle_t 52 53 #define ENTRY_ITERATE IPT_ENTRY_ITERATE 54 #define TABLE_MAXNAMELEN IPT_TABLE_MAXNAMELEN 55 #define FUNCTION_MAXNAMELEN IPT_FUNCTION_MAXNAMELEN 56 57 #define GET_TARGET ipt_get_target 58 59 #define ERROR_TARGET IPT_ERROR_TARGET 60 #define NUMHOOKS NF_IP_NUMHOOKS 61 62 #define IPT_CHAINLABEL ipt_chainlabel 63 64 #define TC_DUMP_ENTRIES dump_entries 65 #define TC_IS_CHAIN iptc_is_chain 66 #define TC_FIRST_CHAIN iptc_first_chain 67 #define TC_NEXT_CHAIN iptc_next_chain 68 #define TC_FIRST_RULE iptc_first_rule 69 #define TC_NEXT_RULE iptc_next_rule 70 #define TC_GET_TARGET iptc_get_target 71 #define TC_BUILTIN iptc_builtin 72 #define TC_GET_POLICY iptc_get_policy 73 #define TC_INSERT_ENTRY iptc_insert_entry 74 #define TC_REPLACE_ENTRY iptc_replace_entry 75 #define TC_APPEND_ENTRY iptc_append_entry 76 #define TC_DELETE_ENTRY iptc_delete_entry 77 #define TC_DELETE_NUM_ENTRY iptc_delete_num_entry 78 #define TC_CHECK_PACKET iptc_check_packet 79 #define TC_FLUSH_ENTRIES iptc_flush_entries 80 #define TC_ZERO_ENTRIES iptc_zero_entries 81 #define TC_READ_COUNTER iptc_read_counter 82 #define TC_ZERO_COUNTER iptc_zero_counter 83 #define TC_SET_COUNTER iptc_set_counter 84 #define TC_CREATE_CHAIN iptc_create_chain 85 #define TC_GET_REFERENCES iptc_get_references 86 #define TC_DELETE_CHAIN iptc_delete_chain 87 #define TC_RENAME_CHAIN iptc_rename_chain 88 #define TC_SET_POLICY iptc_set_policy 89 #define TC_GET_RAW_SOCKET iptc_get_raw_socket 90 #define TC_INIT iptc_init 91 #define TC_FREE iptc_free 92 #define TC_COMMIT iptc_commit 93 #define TC_STRERROR iptc_strerror 94 #define TC_NUM_RULES iptc_num_rules 95 #define TC_GET_RULE iptc_get_rule 96 97 #define TC_AF AF_INET 98 #define TC_IPPROTO IPPROTO_IP 99 100 #define SO_SET_REPLACE IPT_SO_SET_REPLACE 101 #define SO_SET_ADD_COUNTERS IPT_SO_SET_ADD_COUNTERS 102 #define SO_GET_INFO IPT_SO_GET_INFO 103 #define SO_GET_ENTRIES IPT_SO_GET_ENTRIES 104 #define SO_GET_VERSION IPT_SO_GET_VERSION 105 106 #define STANDARD_TARGET IPT_STANDARD_TARGET 107 #define LABEL_RETURN IPTC_LABEL_RETURN 108 #define LABEL_ACCEPT IPTC_LABEL_ACCEPT 109 #define LABEL_DROP IPTC_LABEL_DROP 110 #define LABEL_QUEUE IPTC_LABEL_QUEUE 111 112 #define ALIGN IPT_ALIGN 113 #define RETURN IPT_RETURN 114 115 #include "libiptc.c" 116 117 #define IP_PARTS_NATIVE(n) \ 118 (unsigned int)((n)>>24)&0xFF, \ 119 (unsigned int)((n)>>16)&0xFF, \ 120 (unsigned int)((n)>>8)&0xFF, \ 121 (unsigned int)((n)&0xFF) 122 123 #define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n)) 124 125 int 126 dump_entry(STRUCT_ENTRY *e, const TC_HANDLE_T handle) 127 { 128 size_t i; 129 STRUCT_ENTRY_TARGET *t; 130 131 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e), 132 iptcb_entry2offset(handle, e)); 133 printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n", 134 IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr)); 135 printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n", 136 IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr)); 137 printf("Interface: `%s'/", e->ip.iniface); 138 for (i = 0; i < IFNAMSIZ; i++) 139 printf("%c", e->ip.iniface_mask[i] ? 'X' : '.'); 140 printf("to `%s'/", e->ip.outiface); 141 for (i = 0; i < IFNAMSIZ; i++) 142 printf("%c", e->ip.outiface_mask[i] ? 'X' : '.'); 143 printf("\nProtocol: %u\n", e->ip.proto); 144 printf("Flags: %02X\n", e->ip.flags); 145 printf("Invflags: %02X\n", e->ip.invflags); 146 printf("Counters: %llu packets, %llu bytes\n", 147 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt); 148 printf("Cache: %08X ", e->nfcache); 149 if (e->nfcache & NFC_ALTERED) printf("ALTERED "); 150 if (e->nfcache & NFC_UNKNOWN) printf("UNKNOWN "); 151 printf("\n"); 152 153 IPT_MATCH_ITERATE(e, print_match); 154 155 t = GET_TARGET(e); 156 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size); 157 if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) { 158 int pos = *(int *)t->data; 159 if (pos < 0) 160 printf("verdict=%s\n", 161 pos == -NF_ACCEPT-1 ? "NF_ACCEPT" 162 : pos == -NF_DROP-1 ? "NF_DROP" 163 : pos == -NF_QUEUE-1 ? "NF_QUEUE" 164 : pos == RETURN ? "RETURN" 165 : "UNKNOWN"); 166 else 167 printf("verdict=%u\n", pos); 168 } else if (strcmp(t->u.user.name, IPT_ERROR_TARGET) == 0) 169 printf("error=`%s'\n", t->data); 170 171 printf("\n"); 172 return 0; 173 } 174 175 static unsigned char * 176 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask) 177 { 178 unsigned int i; 179 unsigned char *mptr; 180 181 /* Always compare head structures: ignore mask here. */ 182 if (a->ip.src.s_addr != b->ip.src.s_addr 183 || a->ip.dst.s_addr != b->ip.dst.s_addr 184 || a->ip.smsk.s_addr != b->ip.smsk.s_addr 185 || a->ip.dmsk.s_addr != b->ip.dmsk.s_addr 186 || a->ip.proto != b->ip.proto 187 || a->ip.flags != b->ip.flags 188 || a->ip.invflags != b->ip.invflags) 189 return NULL; 190 191 for (i = 0; i < IFNAMSIZ; i++) { 192 if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i]) 193 return NULL; 194 if ((a->ip.iniface[i] & a->ip.iniface_mask[i]) 195 != (b->ip.iniface[i] & b->ip.iniface_mask[i])) 196 return NULL; 197 if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i]) 198 return NULL; 199 if ((a->ip.outiface[i] & a->ip.outiface_mask[i]) 200 != (b->ip.outiface[i] & b->ip.outiface_mask[i])) 201 return NULL; 202 } 203 204 if (a->nfcache != b->nfcache 205 || a->target_offset != b->target_offset 206 || a->next_offset != b->next_offset) 207 return NULL; 208 209 mptr = matchmask + sizeof(STRUCT_ENTRY); 210 if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr)) 211 return NULL; 212 mptr += IPT_ALIGN(sizeof(struct ipt_entry_target)); 213 214 return mptr; 215 } 216 217 #if 0 218 /***************************** DEBUGGING ********************************/ 219 static inline int 220 unconditional(const struct ipt_ip *ip) 221 { 222 unsigned int i; 223 224 for (i = 0; i < sizeof(*ip)/sizeof(u_int32_t); i++) 225 if (((u_int32_t *)ip)[i]) 226 return 0; 227 228 return 1; 229 } 230 231 static inline int 232 check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off) 233 { 234 assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH)); 235 assert(ALIGN(m->u.match_size) == m->u.match_size); 236 237 (*off) += m->u.match_size; 238 return 0; 239 } 240 241 static inline int 242 check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off, 243 unsigned int user_offset, int *was_return, 244 TC_HANDLE_T h) 245 { 246 unsigned int toff; 247 STRUCT_STANDARD_TARGET *t; 248 249 assert(e->target_offset >= sizeof(STRUCT_ENTRY)); 250 assert(e->next_offset >= e->target_offset 251 + sizeof(STRUCT_ENTRY_TARGET)); 252 toff = sizeof(STRUCT_ENTRY); 253 IPT_MATCH_ITERATE(e, check_match, &toff); 254 255 assert(toff == e->target_offset); 256 257 t = (STRUCT_STANDARD_TARGET *) 258 GET_TARGET((STRUCT_ENTRY *)e); 259 /* next_offset will have to be multiple of entry alignment. */ 260 assert(e->next_offset == ALIGN(e->next_offset)); 261 assert(e->target_offset == ALIGN(e->target_offset)); 262 assert(t->target.u.target_size == ALIGN(t->target.u.target_size)); 263 assert(!TC_IS_CHAIN(t->target.u.user.name, h)); 264 265 if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) { 266 assert(t->target.u.target_size 267 == ALIGN(sizeof(STRUCT_STANDARD_TARGET))); 268 269 assert(t->verdict == -NF_DROP-1 270 || t->verdict == -NF_ACCEPT-1 271 || t->verdict == RETURN 272 || t->verdict < (int)h->entries->size); 273 274 if (t->verdict >= 0) { 275 STRUCT_ENTRY *te = get_entry(h, t->verdict); 276 int idx; 277 278 idx = iptcb_entry2index(h, te); 279 assert(strcmp(GET_TARGET(te)->u.user.name, 280 IPT_ERROR_TARGET) 281 != 0); 282 assert(te != e); 283 284 /* Prior node must be error node, or this node. */ 285 assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset 286 || strcmp(GET_TARGET(index2entry(h, idx-1)) 287 ->u.user.name, IPT_ERROR_TARGET) 288 == 0); 289 } 290 291 if (t->verdict == RETURN 292 && unconditional(&e->ip) 293 && e->target_offset == sizeof(*e)) 294 *was_return = 1; 295 else 296 *was_return = 0; 297 } else if (strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0) { 298 assert(t->target.u.target_size 299 == ALIGN(sizeof(struct ipt_error_target))); 300 301 /* If this is in user area, previous must have been return */ 302 if (*off > user_offset) 303 assert(*was_return); 304 305 *was_return = 0; 306 } 307 else *was_return = 0; 308 309 if (*off == user_offset) 310 assert(strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0); 311 312 (*off) += e->next_offset; 313 (*i)++; 314 return 0; 315 } 316 317 #ifdef IPTC_DEBUG 318 /* Do every conceivable sanity check on the handle */ 319 static void 320 do_check(TC_HANDLE_T h, unsigned int line) 321 { 322 unsigned int i, n; 323 unsigned int user_offset; /* Offset of first user chain */ 324 int was_return; 325 326 assert(h->changed == 0 || h->changed == 1); 327 if (strcmp(h->info.name, "filter") == 0) { 328 assert(h->info.valid_hooks 329 == (1 << NF_IP_LOCAL_IN 330 | 1 << NF_IP_FORWARD 331 | 1 << NF_IP_LOCAL_OUT)); 332 333 /* Hooks should be first three */ 334 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0); 335 336 n = get_chain_end(h, 0); 337 n += get_entry(h, n)->next_offset; 338 assert(h->info.hook_entry[NF_IP_FORWARD] == n); 339 340 n = get_chain_end(h, n); 341 n += get_entry(h, n)->next_offset; 342 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 343 344 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 345 } else if (strcmp(h->info.name, "nat") == 0) { 346 assert((h->info.valid_hooks 347 == (1 << NF_IP_PRE_ROUTING 348 | 1 << NF_IP_POST_ROUTING 349 | 1 << NF_IP_LOCAL_OUT)) || 350 (h->info.valid_hooks 351 == (1 << NF_IP_PRE_ROUTING 352 | 1 << NF_IP_LOCAL_IN 353 | 1 << NF_IP_POST_ROUTING 354 | 1 << NF_IP_LOCAL_OUT))); 355 356 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 357 358 n = get_chain_end(h, 0); 359 360 n += get_entry(h, n)->next_offset; 361 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n); 362 n = get_chain_end(h, n); 363 364 n += get_entry(h, n)->next_offset; 365 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 366 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 367 368 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) { 369 n = get_chain_end(h, n); 370 n += get_entry(h, n)->next_offset; 371 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n); 372 user_offset = h->info.hook_entry[NF_IP_LOCAL_IN]; 373 } 374 375 } else if (strcmp(h->info.name, "mangle") == 0) { 376 /* This code is getting ugly because linux < 2.4.18-pre6 had 377 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks 378 * */ 379 assert((h->info.valid_hooks 380 == (1 << NF_IP_PRE_ROUTING 381 | 1 << NF_IP_LOCAL_OUT)) || 382 (h->info.valid_hooks 383 == (1 << NF_IP_PRE_ROUTING 384 | 1 << NF_IP_LOCAL_IN 385 | 1 << NF_IP_FORWARD 386 | 1 << NF_IP_LOCAL_OUT 387 | 1 << NF_IP_POST_ROUTING))); 388 389 /* Hooks should be first five */ 390 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 391 392 n = get_chain_end(h, 0); 393 394 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) { 395 n += get_entry(h, n)->next_offset; 396 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n); 397 n = get_chain_end(h, n); 398 } 399 400 if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) { 401 n += get_entry(h, n)->next_offset; 402 assert(h->info.hook_entry[NF_IP_FORWARD] == n); 403 n = get_chain_end(h, n); 404 } 405 406 n += get_entry(h, n)->next_offset; 407 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 408 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 409 410 if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) { 411 n = get_chain_end(h, n); 412 n += get_entry(h, n)->next_offset; 413 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n); 414 user_offset = h->info.hook_entry[NF_IP_POST_ROUTING]; 415 } 416 } else if (strcmp(h->info.name, "raw") == 0) { 417 assert(h->info.valid_hooks 418 == (1 << NF_IP_PRE_ROUTING 419 | 1 << NF_IP_LOCAL_OUT)); 420 421 /* Hooks should be first three */ 422 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 423 424 n = get_chain_end(h, n); 425 n += get_entry(h, n)->next_offset; 426 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 427 428 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 429 430 #ifdef NF_IP_DROPPING 431 } else if (strcmp(h->info.name, "drop") == 0) { 432 assert(h->info.valid_hooks == (1 << NF_IP_DROPPING)); 433 434 /* Hook should be first */ 435 assert(h->info.hook_entry[NF_IP_DROPPING] == 0); 436 user_offset = 0; 437 #endif 438 } else { 439 fprintf(stderr, "Unknown table `%s'\n", h->info.name); 440 abort(); 441 } 442 443 /* User chain == end of last builtin + policy entry */ 444 user_offset = get_chain_end(h, user_offset); 445 user_offset += get_entry(h, user_offset)->next_offset; 446 447 /* Overflows should be end of entry chains, and unconditional 448 policy nodes. */ 449 for (i = 0; i < NUMHOOKS; i++) { 450 STRUCT_ENTRY *e; 451 STRUCT_STANDARD_TARGET *t; 452 453 if (!(h->info.valid_hooks & (1 << i))) 454 continue; 455 assert(h->info.underflow[i] 456 == get_chain_end(h, h->info.hook_entry[i])); 457 458 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i])); 459 assert(unconditional(&e->ip)); 460 assert(e->target_offset == sizeof(*e)); 461 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e); 462 assert(t->target.u.target_size == ALIGN(sizeof(*t))); 463 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t))); 464 465 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0); 466 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1); 467 468 /* Hooks and underflows must be valid entries */ 469 entry2index(h, get_entry(h, h->info.hook_entry[i])); 470 entry2index(h, get_entry(h, h->info.underflow[i])); 471 } 472 473 assert(h->info.size 474 >= h->info.num_entries * (sizeof(STRUCT_ENTRY) 475 +sizeof(STRUCT_STANDARD_TARGET))); 476 477 assert(h->entries.size 478 >= (h->new_number 479 * (sizeof(STRUCT_ENTRY) 480 + sizeof(STRUCT_STANDARD_TARGET)))); 481 assert(strcmp(h->info.name, h->entries.name) == 0); 482 483 i = 0; n = 0; 484 was_return = 0; 485 /* Check all the entries. */ 486 ENTRY_ITERATE(h->entries.entrytable, h->entries.size, 487 check_entry, &i, &n, user_offset, &was_return, h); 488 489 assert(i == h->new_number); 490 assert(n == h->entries.size); 491 492 /* Final entry must be error node */ 493 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1)) 494 ->u.user.name, 495 ERROR_TARGET) == 0); 496 } 497 #endif /*IPTC_DEBUG*/ 498 499 #endif 500
