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 21 #ifdef DEBUG_CONNTRACK 22 #define inline 23 #endif 24 25 #if !defined(__ANDROID__) && (!defined(__GLIBC__) || (__GLIBC__ < 2)) 26 typedef unsigned int socklen_t; 27 #endif 28 29 #include "libiptc/libiptc.h" 30 31 #define IP_VERSION 4 32 #define IP_OFFSET 0x1FFF 33 34 #define HOOK_PRE_ROUTING NF_IP_PRE_ROUTING 35 #define HOOK_LOCAL_IN NF_IP_LOCAL_IN 36 #define HOOK_FORWARD NF_IP_FORWARD 37 #define HOOK_LOCAL_OUT NF_IP_LOCAL_OUT 38 #define HOOK_POST_ROUTING NF_IP_POST_ROUTING 39 40 #define STRUCT_ENTRY_TARGET struct xt_entry_target 41 #define STRUCT_ENTRY struct ipt_entry 42 #define STRUCT_ENTRY_MATCH struct xt_entry_match 43 #define STRUCT_GETINFO struct ipt_getinfo 44 #define STRUCT_GET_ENTRIES struct ipt_get_entries 45 #define STRUCT_COUNTERS struct xt_counters 46 #define STRUCT_COUNTERS_INFO struct xt_counters_info 47 #define STRUCT_STANDARD_TARGET struct xt_standard_target 48 #define STRUCT_REPLACE struct ipt_replace 49 50 #define ENTRY_ITERATE IPT_ENTRY_ITERATE 51 #define TABLE_MAXNAMELEN XT_TABLE_MAXNAMELEN 52 #define FUNCTION_MAXNAMELEN XT_FUNCTION_MAXNAMELEN 53 54 #define GET_TARGET ipt_get_target 55 56 #define ERROR_TARGET XT_ERROR_TARGET 57 #define NUMHOOKS NF_IP_NUMHOOKS 58 59 #define IPT_CHAINLABEL xt_chainlabel 60 61 #define TC_DUMP_ENTRIES dump_entries 62 #define TC_IS_CHAIN iptc_is_chain 63 #define TC_FIRST_CHAIN iptc_first_chain 64 #define TC_NEXT_CHAIN iptc_next_chain 65 #define TC_FIRST_RULE iptc_first_rule 66 #define TC_NEXT_RULE iptc_next_rule 67 #define TC_GET_TARGET iptc_get_target 68 #define TC_BUILTIN iptc_builtin 69 #define TC_GET_POLICY iptc_get_policy 70 #define TC_INSERT_ENTRY iptc_insert_entry 71 #define TC_REPLACE_ENTRY iptc_replace_entry 72 #define TC_APPEND_ENTRY iptc_append_entry 73 #define TC_CHECK_ENTRY iptc_check_entry 74 #define TC_DELETE_ENTRY iptc_delete_entry 75 #define TC_DELETE_NUM_ENTRY iptc_delete_num_entry 76 #define TC_FLUSH_ENTRIES iptc_flush_entries 77 #define TC_ZERO_ENTRIES iptc_zero_entries 78 #define TC_READ_COUNTER iptc_read_counter 79 #define TC_ZERO_COUNTER iptc_zero_counter 80 #define TC_SET_COUNTER iptc_set_counter 81 #define TC_CREATE_CHAIN iptc_create_chain 82 #define TC_GET_REFERENCES iptc_get_references 83 #define TC_DELETE_CHAIN iptc_delete_chain 84 #define TC_RENAME_CHAIN iptc_rename_chain 85 #define TC_SET_POLICY iptc_set_policy 86 #define TC_GET_RAW_SOCKET iptc_get_raw_socket 87 #define TC_INIT iptc_init 88 #define TC_FREE iptc_free 89 #define TC_COMMIT iptc_commit 90 #define TC_STRERROR iptc_strerror 91 #define TC_NUM_RULES iptc_num_rules 92 #define TC_GET_RULE iptc_get_rule 93 #define TC_OPS iptc_ops 94 95 #define TC_AF AF_INET 96 #define TC_IPPROTO IPPROTO_IP 97 98 #define SO_SET_REPLACE IPT_SO_SET_REPLACE 99 #define SO_SET_ADD_COUNTERS IPT_SO_SET_ADD_COUNTERS 100 #define SO_GET_INFO IPT_SO_GET_INFO 101 #define SO_GET_ENTRIES IPT_SO_GET_ENTRIES 102 #define SO_GET_VERSION IPT_SO_GET_VERSION 103 104 #define STANDARD_TARGET XT_STANDARD_TARGET 105 #define LABEL_RETURN IPTC_LABEL_RETURN 106 #define LABEL_ACCEPT IPTC_LABEL_ACCEPT 107 #define LABEL_DROP IPTC_LABEL_DROP 108 #define LABEL_QUEUE IPTC_LABEL_QUEUE 109 110 #define ALIGN XT_ALIGN 111 #define RETURN XT_RETURN 112 113 #include "libiptc.c" 114 115 #define IP_PARTS_NATIVE(n) \ 116 (unsigned int)((n)>>24)&0xFF, \ 117 (unsigned int)((n)>>16)&0xFF, \ 118 (unsigned int)((n)>>8)&0xFF, \ 119 (unsigned int)((n)&0xFF) 120 121 #define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n)) 122 123 static int 124 dump_entry(struct ipt_entry *e, struct xtc_handle *const handle) 125 { 126 size_t i; 127 STRUCT_ENTRY_TARGET *t; 128 129 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e), 130 iptcb_entry2offset(handle, e)); 131 printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n", 132 IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr)); 133 printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n", 134 IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr)); 135 printf("Interface: `%s'/", e->ip.iniface); 136 for (i = 0; i < IFNAMSIZ; i++) 137 printf("%c", e->ip.iniface_mask[i] ? 'X' : '.'); 138 printf("to `%s'/", e->ip.outiface); 139 for (i = 0; i < IFNAMSIZ; i++) 140 printf("%c", e->ip.outiface_mask[i] ? 'X' : '.'); 141 printf("\nProtocol: %u\n", e->ip.proto); 142 printf("Flags: %02X\n", e->ip.flags); 143 printf("Invflags: %02X\n", e->ip.invflags); 144 printf("Counters: %llu packets, %llu bytes\n", 145 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt); 146 printf("Cache: %08X\n", e->nfcache); 147 148 IPT_MATCH_ITERATE(e, print_match); 149 150 t = GET_TARGET(e); 151 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size); 152 if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) { 153 const unsigned char *data = t->data; 154 int pos = *(const int *)data; 155 if (pos < 0) 156 printf("verdict=%s\n", 157 pos == -NF_ACCEPT-1 ? "NF_ACCEPT" 158 : pos == -NF_DROP-1 ? "NF_DROP" 159 : pos == -NF_QUEUE-1 ? "NF_QUEUE" 160 : pos == RETURN ? "RETURN" 161 : "UNKNOWN"); 162 else 163 printf("verdict=%u\n", pos); 164 } else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0) 165 printf("error=`%s'\n", t->data); 166 167 printf("\n"); 168 return 0; 169 } 170 171 static unsigned char * 172 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask) 173 { 174 unsigned int i; 175 unsigned char *mptr; 176 177 /* Always compare head structures: ignore mask here. */ 178 if (a->ip.src.s_addr != b->ip.src.s_addr 179 || a->ip.dst.s_addr != b->ip.dst.s_addr 180 || a->ip.smsk.s_addr != b->ip.smsk.s_addr 181 || a->ip.dmsk.s_addr != b->ip.dmsk.s_addr 182 || a->ip.proto != b->ip.proto 183 || a->ip.flags != b->ip.flags 184 || a->ip.invflags != b->ip.invflags) 185 return NULL; 186 187 for (i = 0; i < IFNAMSIZ; i++) { 188 if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i]) 189 return NULL; 190 if ((a->ip.iniface[i] & a->ip.iniface_mask[i]) 191 != (b->ip.iniface[i] & b->ip.iniface_mask[i])) 192 return NULL; 193 if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i]) 194 return NULL; 195 if ((a->ip.outiface[i] & a->ip.outiface_mask[i]) 196 != (b->ip.outiface[i] & b->ip.outiface_mask[i])) 197 return NULL; 198 } 199 200 if (a->target_offset != b->target_offset 201 || a->next_offset != b->next_offset) 202 return NULL; 203 204 mptr = matchmask + sizeof(STRUCT_ENTRY); 205 if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr)) 206 return NULL; 207 mptr += XT_ALIGN(sizeof(struct xt_entry_target)); 208 209 return mptr; 210 } 211 212 #if 0 213 /***************************** DEBUGGING ********************************/ 214 static inline int 215 unconditional(const struct ipt_ip *ip) 216 { 217 unsigned int i; 218 219 for (i = 0; i < sizeof(*ip)/sizeof(uint32_t); i++) 220 if (((uint32_t *)ip)[i]) 221 return 0; 222 223 return 1; 224 } 225 226 static inline int 227 check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off) 228 { 229 assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH)); 230 assert(ALIGN(m->u.match_size) == m->u.match_size); 231 232 (*off) += m->u.match_size; 233 return 0; 234 } 235 236 static inline int 237 check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off, 238 unsigned int user_offset, int *was_return, 239 struct xtc_handle *h) 240 { 241 unsigned int toff; 242 STRUCT_STANDARD_TARGET *t; 243 244 assert(e->target_offset >= sizeof(STRUCT_ENTRY)); 245 assert(e->next_offset >= e->target_offset 246 + sizeof(STRUCT_ENTRY_TARGET)); 247 toff = sizeof(STRUCT_ENTRY); 248 IPT_MATCH_ITERATE(e, check_match, &toff); 249 250 assert(toff == e->target_offset); 251 252 t = (STRUCT_STANDARD_TARGET *) 253 GET_TARGET((STRUCT_ENTRY *)e); 254 /* next_offset will have to be multiple of entry alignment. */ 255 assert(e->next_offset == ALIGN(e->next_offset)); 256 assert(e->target_offset == ALIGN(e->target_offset)); 257 assert(t->target.u.target_size == ALIGN(t->target.u.target_size)); 258 assert(!TC_IS_CHAIN(t->target.u.user.name, h)); 259 260 if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) { 261 assert(t->target.u.target_size 262 == ALIGN(sizeof(STRUCT_STANDARD_TARGET))); 263 264 assert(t->verdict == -NF_DROP-1 265 || t->verdict == -NF_ACCEPT-1 266 || t->verdict == RETURN 267 || t->verdict < (int)h->entries->size); 268 269 if (t->verdict >= 0) { 270 STRUCT_ENTRY *te = get_entry(h, t->verdict); 271 int idx; 272 273 idx = iptcb_entry2index(h, te); 274 assert(strcmp(GET_TARGET(te)->u.user.name, 275 XT_ERROR_TARGET) 276 != 0); 277 assert(te != e); 278 279 /* Prior node must be error node, or this node. */ 280 assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset 281 || strcmp(GET_TARGET(index2entry(h, idx-1)) 282 ->u.user.name, XT_ERROR_TARGET) 283 == 0); 284 } 285 286 if (t->verdict == RETURN 287 && unconditional(&e->ip) 288 && e->target_offset == sizeof(*e)) 289 *was_return = 1; 290 else 291 *was_return = 0; 292 } else if (strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0) { 293 assert(t->target.u.target_size 294 == ALIGN(sizeof(struct ipt_error_target))); 295 296 /* If this is in user area, previous must have been return */ 297 if (*off > user_offset) 298 assert(*was_return); 299 300 *was_return = 0; 301 } 302 else *was_return = 0; 303 304 if (*off == user_offset) 305 assert(strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0); 306 307 (*off) += e->next_offset; 308 (*i)++; 309 return 0; 310 } 311 312 #ifdef IPTC_DEBUG 313 /* Do every conceivable sanity check on the handle */ 314 static void 315 do_check(struct xtc_handle *h, unsigned int line) 316 { 317 unsigned int i, n; 318 unsigned int user_offset; /* Offset of first user chain */ 319 int was_return; 320 321 assert(h->changed == 0 || h->changed == 1); 322 if (strcmp(h->info.name, "filter") == 0) { 323 assert(h->info.valid_hooks 324 == (1 << NF_IP_LOCAL_IN 325 | 1 << NF_IP_FORWARD 326 | 1 << NF_IP_LOCAL_OUT)); 327 328 /* Hooks should be first three */ 329 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0); 330 331 n = get_chain_end(h, 0); 332 n += get_entry(h, n)->next_offset; 333 assert(h->info.hook_entry[NF_IP_FORWARD] == n); 334 335 n = get_chain_end(h, n); 336 n += get_entry(h, n)->next_offset; 337 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 338 339 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 340 } else if (strcmp(h->info.name, "nat") == 0) { 341 assert((h->info.valid_hooks 342 == (1 << NF_IP_PRE_ROUTING 343 | 1 << NF_IP_POST_ROUTING 344 | 1 << NF_IP_LOCAL_OUT)) || 345 (h->info.valid_hooks 346 == (1 << NF_IP_PRE_ROUTING 347 | 1 << NF_IP_LOCAL_IN 348 | 1 << NF_IP_POST_ROUTING 349 | 1 << NF_IP_LOCAL_OUT))); 350 351 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 352 353 n = get_chain_end(h, 0); 354 355 n += get_entry(h, n)->next_offset; 356 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n); 357 n = get_chain_end(h, n); 358 359 n += get_entry(h, n)->next_offset; 360 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 361 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 362 363 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) { 364 n = get_chain_end(h, n); 365 n += get_entry(h, n)->next_offset; 366 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n); 367 user_offset = h->info.hook_entry[NF_IP_LOCAL_IN]; 368 } 369 370 } else if (strcmp(h->info.name, "mangle") == 0) { 371 /* This code is getting ugly because linux < 2.4.18-pre6 had 372 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks 373 * */ 374 assert((h->info.valid_hooks 375 == (1 << NF_IP_PRE_ROUTING 376 | 1 << NF_IP_LOCAL_OUT)) || 377 (h->info.valid_hooks 378 == (1 << NF_IP_PRE_ROUTING 379 | 1 << NF_IP_LOCAL_IN 380 | 1 << NF_IP_FORWARD 381 | 1 << NF_IP_LOCAL_OUT 382 | 1 << NF_IP_POST_ROUTING))); 383 384 /* Hooks should be first five */ 385 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 386 387 n = get_chain_end(h, 0); 388 389 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) { 390 n += get_entry(h, n)->next_offset; 391 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n); 392 n = get_chain_end(h, n); 393 } 394 395 if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) { 396 n += get_entry(h, n)->next_offset; 397 assert(h->info.hook_entry[NF_IP_FORWARD] == n); 398 n = get_chain_end(h, n); 399 } 400 401 n += get_entry(h, n)->next_offset; 402 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 403 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 404 405 if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) { 406 n = get_chain_end(h, n); 407 n += get_entry(h, n)->next_offset; 408 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n); 409 user_offset = h->info.hook_entry[NF_IP_POST_ROUTING]; 410 } 411 } else if (strcmp(h->info.name, "raw") == 0) { 412 assert(h->info.valid_hooks 413 == (1 << NF_IP_PRE_ROUTING 414 | 1 << NF_IP_LOCAL_OUT)); 415 416 /* Hooks should be first three */ 417 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0); 418 419 n = get_chain_end(h, n); 420 n += get_entry(h, n)->next_offset; 421 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n); 422 423 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT]; 424 } else { 425 fprintf(stderr, "Unknown table `%s'\n", h->info.name); 426 abort(); 427 } 428 429 /* User chain == end of last builtin + policy entry */ 430 user_offset = get_chain_end(h, user_offset); 431 user_offset += get_entry(h, user_offset)->next_offset; 432 433 /* Overflows should be end of entry chains, and unconditional 434 policy nodes. */ 435 for (i = 0; i < NUMHOOKS; i++) { 436 STRUCT_ENTRY *e; 437 STRUCT_STANDARD_TARGET *t; 438 439 if (!(h->info.valid_hooks & (1 << i))) 440 continue; 441 assert(h->info.underflow[i] 442 == get_chain_end(h, h->info.hook_entry[i])); 443 444 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i])); 445 assert(unconditional(&e->ip)); 446 assert(e->target_offset == sizeof(*e)); 447 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e); 448 assert(t->target.u.target_size == ALIGN(sizeof(*t))); 449 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t))); 450 451 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0); 452 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1); 453 454 /* Hooks and underflows must be valid entries */ 455 entry2index(h, get_entry(h, h->info.hook_entry[i])); 456 entry2index(h, get_entry(h, h->info.underflow[i])); 457 } 458 459 assert(h->info.size 460 >= h->info.num_entries * (sizeof(STRUCT_ENTRY) 461 +sizeof(STRUCT_STANDARD_TARGET))); 462 463 assert(h->entries.size 464 >= (h->new_number 465 * (sizeof(STRUCT_ENTRY) 466 + sizeof(STRUCT_STANDARD_TARGET)))); 467 assert(strcmp(h->info.name, h->entries.name) == 0); 468 469 i = 0; n = 0; 470 was_return = 0; 471 /* Check all the entries. */ 472 ENTRY_ITERATE(h->entries.entrytable, h->entries.size, 473 check_entry, &i, &n, user_offset, &was_return, h); 474 475 assert(i == h->new_number); 476 assert(n == h->entries.size); 477 478 /* Final entry must be error node */ 479 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1)) 480 ->u.user.name, 481 ERROR_TARGET) == 0); 482 } 483 #endif /*IPTC_DEBUG*/ 484 485 #endif 486
