1 /* 2 * firewall3 - 3rd OpenWrt UCI firewall implementation 3 * 4 * Copyright (C) 2013 Jo-Philipp Wich <jo@mein.io> 5 * 6 * Permission to use, copy, modify, and/or distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include "defaults.h" 20 21 22 #define C(f, tbl, def, fmt) \ 23 { FW3_FAMILY_##f, FW3_TABLE_##tbl, FW3_FLAG_##def, fmt } 24 25 static const struct fw3_chain_spec default_chains[] = { 26 C(ANY, FILTER, UNSPEC, "reject"), 27 C(ANY, FILTER, CUSTOM_CHAINS, "input_rule"), 28 C(ANY, FILTER, CUSTOM_CHAINS, "output_rule"), 29 C(ANY, FILTER, CUSTOM_CHAINS, "forwarding_rule"), 30 C(ANY, FILTER, SYN_FLOOD, "syn_flood"), 31 32 C(V4, NAT, CUSTOM_CHAINS, "prerouting_rule"), 33 C(V4, NAT, CUSTOM_CHAINS, "postrouting_rule"), 34 35 { } 36 }; 37 38 const struct fw3_option fw3_flag_opts[] = { 39 FW3_OPT("input", target, defaults, policy_input), 40 FW3_OPT("forward", target, defaults, policy_forward), 41 FW3_OPT("output", target, defaults, policy_output), 42 43 FW3_OPT("drop_invalid", bool, defaults, drop_invalid), 44 FW3_OPT("tcp_reject_code", reject_code, defaults, tcp_reject_code), 45 FW3_OPT("any_reject_code", reject_code, defaults, any_reject_code), 46 47 FW3_OPT("syn_flood", bool, defaults, syn_flood), 48 FW3_OPT("synflood_protect", bool, defaults, syn_flood), 49 FW3_OPT("synflood_rate", limit, defaults, syn_flood_rate), 50 FW3_OPT("synflood_burst", int, defaults, syn_flood_rate.burst), 51 52 FW3_OPT("tcp_syncookies", bool, defaults, tcp_syncookies), 53 FW3_OPT("tcp_ecn", int, defaults, tcp_ecn), 54 FW3_OPT("tcp_window_scaling", bool, defaults, tcp_window_scaling), 55 56 FW3_OPT("accept_redirects", bool, defaults, accept_redirects), 57 FW3_OPT("accept_source_route", bool, defaults, accept_source_route), 58 59 FW3_OPT("auto_helper", bool, defaults, auto_helper), 60 FW3_OPT("custom_chains", bool, defaults, custom_chains), 61 FW3_OPT("disable_ipv6", bool, defaults, disable_ipv6), 62 FW3_OPT("flow_offloading", bool, defaults, flow_offloading), 63 FW3_OPT("flow_offloading_hw", bool, defaults, flow_offloading_hw), 64 65 FW3_OPT("__flags_v4", int, defaults, flags[0]), 66 FW3_OPT("__flags_v6", int, defaults, flags[1]), 67 68 { } 69 }; 70 71 72 static void 73 check_policy(struct uci_element *e, enum fw3_flag *pol, const char *name) 74 { 75 if (*pol == FW3_FLAG_UNSPEC) 76 { 77 warn_elem(e, "has no %s policy specified, defaulting to DROP", name); 78 *pol = FW3_FLAG_DROP; 79 } 80 else if (*pol > FW3_FLAG_DROP) 81 { 82 warn_elem(e, "has invalid %s policy, defaulting to DROP", name); 83 *pol = FW3_FLAG_DROP; 84 } 85 } 86 87 static void 88 check_target(struct uci_element *e, bool *available, const char *target, const bool ipv6) 89 { 90 const bool b = fw3_has_target(ipv6, target); 91 if (!b) 92 { 93 warn_elem(e, "requires unavailable target extension %s, disabling", target); 94 } 95 *available = b; 96 } 97 98 static void 99 check_any_reject_code(struct uci_element *e, enum fw3_reject_code *any_reject_code) 100 { 101 if (*any_reject_code == FW3_REJECT_CODE_TCP_RESET) { 102 warn_elem(e, "tcp-reset not valid for any_reject_code, defaulting to port-unreach"); 103 *any_reject_code = FW3_REJECT_CODE_PORT_UNREACH; 104 } 105 } 106 107 static const char* 108 get_reject_code(enum fw3_family family, enum fw3_reject_code reject_code) 109 { 110 switch (reject_code) { 111 case FW3_REJECT_CODE_TCP_RESET: 112 return "tcp-reset"; 113 case FW3_REJECT_CODE_PORT_UNREACH: 114 return "port-unreach"; 115 case FW3_REJECT_CODE_ADM_PROHIBITED: 116 return family == FW3_FAMILY_V6 ? "adm-prohibited": "admin-prohib"; 117 default: 118 return "unknown"; 119 } 120 } 121 122 void 123 fw3_load_defaults(struct fw3_state *state, struct uci_package *p) 124 { 125 struct uci_section *s; 126 struct uci_element *e; 127 struct fw3_defaults *defs = &state->defaults; 128 129 bool flow_offload_avaliable = false; 130 bool seen = false; 131 132 defs->tcp_reject_code = FW3_REJECT_CODE_TCP_RESET; 133 defs->any_reject_code = FW3_REJECT_CODE_PORT_UNREACH; 134 defs->syn_flood_rate.rate = 25; 135 defs->syn_flood_rate.burst = 50; 136 defs->tcp_syncookies = true; 137 defs->tcp_window_scaling = true; 138 defs->custom_chains = true; 139 defs->auto_helper = true; 140 141 uci_foreach_element(&p->sections, e) 142 { 143 s = uci_to_section(e); 144 145 if (strcmp(s->type, "defaults")) 146 continue; 147 148 if (seen) 149 { 150 warn_elem(e, "ignoring duplicate section"); 151 continue; 152 } 153 154 if(!fw3_parse_options(&state->defaults, fw3_flag_opts, s)) 155 warn_elem(e, "has invalid options"); 156 157 check_policy(e, &defs->policy_input, "input"); 158 check_policy(e, &defs->policy_output, "output"); 159 check_policy(e, &defs->policy_forward, "forward"); 160 161 check_any_reject_code(e, &defs->any_reject_code); 162 163 /* exists in both ipv4 and ipv6, if at all, so only check ipv4 */ 164 check_target(e, &flow_offload_avaliable, "FLOWOFFLOAD", false); 165 166 if (!flow_offload_avaliable) 167 defs->flow_offloading = false; 168 } 169 } 170 171 void 172 fw3_print_default_chains(struct fw3_ipt_handle *handle, struct fw3_state *state, 173 bool reload) 174 { 175 struct fw3_defaults *defs = &state->defaults; 176 const struct fw3_chain_spec *c; 177 178 #define policy(t) \ 179 ((t == FW3_FLAG_REJECT) ? FW3_FLAG_DROP : t) 180 181 if (handle->family == FW3_FAMILY_V6 && defs->disable_ipv6) 182 return; 183 184 if (handle->table == FW3_TABLE_FILTER) 185 { 186 fw3_ipt_set_policy(handle, "INPUT", policy(defs->policy_input)); 187 fw3_ipt_set_policy(handle, "OUTPUT", policy(defs->policy_output)); 188 fw3_ipt_set_policy(handle, "FORWARD", policy(defs->policy_forward)); 189 } 190 191 if (defs->custom_chains) 192 set(defs->flags, handle->family, FW3_FLAG_CUSTOM_CHAINS); 193 194 if (defs->syn_flood) 195 set(defs->flags, handle->family, FW3_FLAG_SYN_FLOOD); 196 197 for (c = default_chains; c->format; c++) 198 { 199 /* don't touch user chains on selective stop */ 200 if (reload && c->flag == FW3_FLAG_CUSTOM_CHAINS) 201 continue; 202 203 if (!fw3_is_family(c, handle->family)) 204 continue; 205 206 if (c->table != handle->table) 207 continue; 208 209 if (c->flag && 210 !fw3_hasbit(defs->flags[handle->family == FW3_FAMILY_V6], c->flag)) 211 continue; 212 213 fw3_ipt_create_chain(handle, c->format); 214 } 215 216 set(defs->flags, handle->family, handle->table); 217 } 218 219 void 220 fw3_print_default_head_rules(struct fw3_ipt_handle *handle, 221 struct fw3_state *state, bool reload) 222 { 223 int i; 224 struct fw3_defaults *defs = &state->defaults; 225 struct fw3_device lodev = { .set = true }; 226 struct fw3_protocol tcp = { .protocol = 6 }; 227 struct fw3_ipt_rule *r; 228 229 const char *chains[] = { 230 "INPUT", "input", 231 "OUTPUT", "output", 232 "FORWARD", "forwarding", 233 }; 234 235 switch (handle->table) 236 { 237 case FW3_TABLE_FILTER: 238 239 sprintf(lodev.name, "lo"); 240 241 r = fw3_ipt_rule_create(handle, NULL, &lodev, NULL, NULL, NULL); 242 fw3_ipt_rule_target(r, "ACCEPT"); 243 fw3_ipt_rule_append(r, "INPUT"); 244 245 r = fw3_ipt_rule_create(handle, NULL, NULL, &lodev, NULL, NULL); 246 fw3_ipt_rule_target(r, "ACCEPT"); 247 fw3_ipt_rule_append(r, "OUTPUT"); 248 249 if (defs->custom_chains) 250 { 251 for (i = 0; i < ARRAY_SIZE(chains); i += 2) 252 { 253 r = fw3_ipt_rule_new(handle); 254 fw3_ipt_rule_comment(r, "Custom %s rule chain", chains[i+1]); 255 fw3_ipt_rule_target(r, "%s_rule", chains[i+1]); 256 fw3_ipt_rule_append(r, chains[i]); 257 } 258 } 259 260 if (defs->flow_offloading) 261 { 262 r = fw3_ipt_rule_new(handle); 263 fw3_ipt_rule_comment(r, "Traffic offloading"); 264 fw3_ipt_rule_extra(r, "-m conntrack --ctstate RELATED,ESTABLISHED"); 265 fw3_ipt_rule_target(r, "FLOWOFFLOAD"); 266 if (defs->flow_offloading_hw) 267 fw3_ipt_rule_addarg(r, false, "--hw", NULL); 268 fw3_ipt_rule_append(r, "FORWARD"); 269 } 270 271 for (i = 0; i < ARRAY_SIZE(chains); i += 2) 272 { 273 r = fw3_ipt_rule_new(handle); 274 fw3_ipt_rule_extra(r, "-m conntrack --ctstate RELATED,ESTABLISHED"); 275 fw3_ipt_rule_target(r, "ACCEPT"); 276 fw3_ipt_rule_append(r, chains[i]); 277 278 if (defs->drop_invalid) 279 { 280 r = fw3_ipt_rule_new(handle); 281 fw3_ipt_rule_extra(r, "-m conntrack --ctstate INVALID"); 282 fw3_ipt_rule_target(r, "DROP"); 283 fw3_ipt_rule_append(r, chains[i]); 284 } 285 } 286 287 if (defs->syn_flood) 288 { 289 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL); 290 fw3_ipt_rule_extra(r, "--syn"); 291 fw3_ipt_rule_limit(r, &defs->syn_flood_rate); 292 fw3_ipt_rule_target(r, "RETURN"); 293 fw3_ipt_rule_append(r, "syn_flood"); 294 295 r = fw3_ipt_rule_new(handle); 296 fw3_ipt_rule_target(r, "DROP"); 297 fw3_ipt_rule_append(r, "syn_flood"); 298 299 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL); 300 fw3_ipt_rule_extra(r, "--syn"); 301 fw3_ipt_rule_target(r, "syn_flood"); 302 fw3_ipt_rule_append(r, "INPUT"); 303 } 304 305 r = fw3_ipt_rule_create(handle, &tcp, NULL, NULL, NULL, NULL); 306 fw3_ipt_rule_target(r, "REJECT"); 307 fw3_ipt_rule_addarg(r, false, "--reject-with", get_reject_code(handle->family, defs->tcp_reject_code)); 308 fw3_ipt_rule_append(r, "reject"); 309 310 r = fw3_ipt_rule_new(handle); 311 fw3_ipt_rule_target(r, "REJECT"); 312 fw3_ipt_rule_addarg(r, false, "--reject-with", get_reject_code(handle->family, defs->any_reject_code)); 313 fw3_ipt_rule_append(r, "reject"); 314 315 break; 316 317 case FW3_TABLE_NAT: 318 if (defs->custom_chains) 319 { 320 r = fw3_ipt_rule_new(handle); 321 fw3_ipt_rule_comment(r, "Custom prerouting rule chain"); 322 fw3_ipt_rule_target(r, "prerouting_rule"); 323 fw3_ipt_rule_append(r, "PREROUTING"); 324 325 r = fw3_ipt_rule_new(handle); 326 fw3_ipt_rule_comment(r, "Custom postrouting rule chain"); 327 fw3_ipt_rule_target(r, "postrouting_rule"); 328 fw3_ipt_rule_append(r, "POSTROUTING"); 329 } 330 break; 331 332 default: 333 break; 334 } 335 } 336 337 void 338 fw3_print_default_tail_rules(struct fw3_ipt_handle *handle, 339 struct fw3_state *state, bool reload) 340 { 341 struct fw3_defaults *defs = &state->defaults; 342 struct fw3_ipt_rule *r; 343 344 if (handle->table != FW3_TABLE_FILTER) 345 return; 346 347 if (defs->policy_input == FW3_FLAG_REJECT) 348 { 349 r = fw3_ipt_rule_new(handle); 350 351 if (!r) 352 return; 353 354 fw3_ipt_rule_target(r, "reject"); 355 fw3_ipt_rule_append(r, "INPUT"); 356 } 357 358 if (defs->policy_output == FW3_FLAG_REJECT) 359 { 360 r = fw3_ipt_rule_new(handle); 361 362 if (!r) 363 return; 364 365 fw3_ipt_rule_target(r, "reject"); 366 fw3_ipt_rule_append(r, "OUTPUT"); 367 } 368 369 if (defs->policy_forward == FW3_FLAG_REJECT) 370 { 371 r = fw3_ipt_rule_new(handle); 372 373 if (!r) 374 return; 375 376 fw3_ipt_rule_target(r, "reject"); 377 fw3_ipt_rule_append(r, "FORWARD"); 378 } 379 } 380 381 static void 382 set_default(const char *name, int set) 383 { 384 FILE *f; 385 char path[sizeof("/proc/sys/net/ipv4/tcp_window_scaling\0")]; 386 387 snprintf(path, sizeof(path), "/proc/sys/net/ipv4/tcp_%s", name); 388 389 info(" * Set tcp_%s to %s", name, set ? "on" : "off"); 390 391 if (!(f = fopen(path, "w"))) 392 { 393 info(" ! Unable to write value: %s", strerror(errno)); 394 return; 395 } 396 397 fprintf(f, "%u\n", set); 398 fclose(f); 399 } 400 401 void 402 fw3_set_defaults(struct fw3_state *state) 403 { 404 set_default("ecn", state->defaults.tcp_ecn); 405 set_default("syncookies", state->defaults.tcp_syncookies); 406 set_default("window_scaling", state->defaults.tcp_window_scaling); 407 } 408 409 void 410 fw3_flush_rules(struct fw3_ipt_handle *handle, struct fw3_state *state, 411 bool reload) 412 { 413 enum fw3_flag policy = reload ? FW3_FLAG_DROP : FW3_FLAG_ACCEPT; 414 struct fw3_defaults *defs = &state->defaults; 415 const struct fw3_chain_spec *c; 416 417 if (!has(defs->flags, handle->family, handle->table)) 418 return; 419 420 if (handle->table == FW3_TABLE_FILTER) 421 { 422 fw3_ipt_set_policy(handle, "INPUT", policy); 423 fw3_ipt_set_policy(handle, "OUTPUT", policy); 424 fw3_ipt_set_policy(handle, "FORWARD", policy); 425 } 426 427 fw3_ipt_delete_id_rules(handle, "INPUT"); 428 fw3_ipt_delete_id_rules(handle, "OUTPUT"); 429 fw3_ipt_delete_id_rules(handle, "FORWARD"); 430 fw3_ipt_delete_id_rules(handle, "PREROUTING"); 431 fw3_ipt_delete_id_rules(handle, "POSTROUTING"); 432 433 for (c = default_chains; c->format; c++) 434 { 435 /* don't touch user chains on selective stop */ 436 if (reload && c->flag == FW3_FLAG_CUSTOM_CHAINS) 437 continue; 438 439 if (!fw3_is_family(c, handle->family)) 440 continue; 441 442 if (c->table != handle->table) 443 continue; 444 445 if (c->flag && !has(defs->flags, handle->family, c->flag)) 446 continue; 447 448 fw3_ipt_flush_chain(handle, c->format); 449 450 /* keep certain basic chains that do not depend on any settings to 451 avoid purging unrelated user rules pointing to them */ 452 if (reload && !c->flag) 453 continue; 454 455 fw3_ipt_delete_chain(handle, c->format); 456 } 457 458 del(defs->flags, handle->family, handle->table); 459 } 460 461 void 462 fw3_flush_all(struct fw3_ipt_handle *handle) 463 { 464 if (handle->table == FW3_TABLE_FILTER) 465 { 466 fw3_ipt_set_policy(handle, "INPUT", FW3_FLAG_ACCEPT); 467 fw3_ipt_set_policy(handle, "OUTPUT", FW3_FLAG_ACCEPT); 468 fw3_ipt_set_policy(handle, "FORWARD", FW3_FLAG_ACCEPT); 469 } 470 471 fw3_ipt_flush(handle); 472 } 473
This page was automatically generated by LXR 0.3.1. • OpenWrt