1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * dhcpcd - DHCP client daemon 4 * Copyright (c) 2006-2019 Roy Marples <roy@marples.name> 5 * All rights reserved 6 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <arpa/inet.h> 30 31 #include <assert.h> 32 #include <errno.h> 33 #include <stdbool.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <unistd.h> 38 39 #define ELOOP_QUEUE 6 40 #include "config.h" 41 #include "arp.h" 42 #include "common.h" 43 #include "dhcp.h" 44 #include "eloop.h" 45 #include "if.h" 46 #include "if-options.h" 47 #include "ipv4.h" 48 #include "ipv4ll.h" 49 #include "logerr.h" 50 #include "sa.h" 51 #include "script.h" 52 53 static const struct in_addr inaddr_llmask = { 54 .s_addr = HTONL(LINKLOCAL_MASK) 55 }; 56 static const struct in_addr inaddr_llbcast = { 57 .s_addr = HTONL(LINKLOCAL_BCAST) 58 }; 59 60 static void ipv4ll_start1(struct interface *, struct arp_state *); 61 62 static in_addr_t 63 ipv4ll_pickaddr(struct interface *ifp) 64 { 65 struct in_addr addr; 66 struct ipv4ll_state *state; 67 68 state = IPV4LL_STATE(ifp); 69 setstate(state->randomstate); 70 71 do { 72 long r; 73 74 again: 75 /* RFC 3927 Section 2.1 states that the first 256 and 76 * last 256 addresses are reserved for future use. 77 * See ipv4ll_start for why we don't use arc4random. */ 78 /* coverity[dont_call] */ 79 r = random(); 80 addr.s_addr = ntohl(LINKLOCAL_ADDR | 81 ((uint32_t)(r % 0xFD00) + 0x0100)); 82 83 /* No point using a failed address */ 84 if (IN_ARE_ADDR_EQUAL(&addr, &state->pickedaddr)) 85 goto again; 86 /* Ensure we don't have the address on another interface */ 87 } while (ipv4_findaddr(ifp->ctx, &addr) != NULL); 88 89 /* Restore the original random state */ 90 setstate(ifp->ctx->randomstate); 91 return addr.s_addr; 92 } 93 94 int 95 ipv4ll_subnetroute(rb_tree_t *routes, struct interface *ifp) 96 { 97 struct ipv4ll_state *state; 98 struct rt *rt; 99 struct in_addr in; 100 101 assert(ifp != NULL); 102 if ((state = IPV4LL_STATE(ifp)) == NULL || 103 state->addr == NULL) 104 return 0; 105 106 if ((rt = rt_new(ifp)) == NULL) 107 return -1; 108 109 in.s_addr = state->addr->addr.s_addr & state->addr->mask.s_addr; 110 sa_in_init(&rt->rt_dest, &in); 111 in.s_addr = state->addr->mask.s_addr; 112 sa_in_init(&rt->rt_netmask, &in); 113 in.s_addr = INADDR_ANY; 114 sa_in_init(&rt->rt_gateway, &in); 115 sa_in_init(&rt->rt_ifa, &state->addr->addr); 116 return rt_proto_add(routes, rt) ? 1 : 0; 117 } 118 119 int 120 ipv4ll_defaultroute(rb_tree_t *routes, struct interface *ifp) 121 { 122 struct ipv4ll_state *state; 123 struct rt *rt; 124 struct in_addr in; 125 126 assert(ifp != NULL); 127 if ((state = IPV4LL_STATE(ifp)) == NULL || 128 state->addr == NULL) 129 return 0; 130 131 if ((rt = rt_new(ifp)) == NULL) 132 return -1; 133 134 in.s_addr = INADDR_ANY; 135 sa_in_init(&rt->rt_dest, &in); 136 sa_in_init(&rt->rt_netmask, &in); 137 sa_in_init(&rt->rt_gateway, &in); 138 sa_in_init(&rt->rt_ifa, &state->addr->addr); 139 return rt_proto_add(routes, rt) ? 1 : 0; 140 } 141 142 ssize_t 143 ipv4ll_env(FILE *fp, const char *prefix, const struct interface *ifp) 144 { 145 const struct ipv4ll_state *state; 146 const char *pf = prefix == NULL ? "" : "_"; 147 struct in_addr netnum; 148 149 assert(ifp != NULL); 150 if ((state = IPV4LL_CSTATE(ifp)) == NULL || state->addr == NULL) 151 return 0; 152 153 /* Emulate a DHCP environment */ 154 if (efprintf(fp, "%s%sip_address=%s", 155 prefix, pf, inet_ntoa(state->addr->addr)) == -1) 156 return -1; 157 if (efprintf(fp, "%s%ssubnet_mask=%s", 158 prefix, pf, inet_ntoa(state->addr->mask)) == -1) 159 return -1; 160 if (efprintf(fp, "%s%ssubnet_cidr=%d", 161 prefix, pf, inet_ntocidr(state->addr->mask)) == -1) 162 return -1; 163 if (efprintf(fp, "%s%sbroadcast_address=%s", 164 prefix, pf, inet_ntoa(state->addr->brd)) == -1) 165 return -1; 166 netnum.s_addr = state->addr->addr.s_addr & state->addr->mask.s_addr; 167 if (efprintf(fp, "%s%snetwork_number=%s", 168 prefix, pf, inet_ntoa(netnum)) == -1) 169 return -1; 170 return 5; 171 } 172 173 static void 174 ipv4ll_announced_arp(struct arp_state *astate) 175 { 176 struct ipv4ll_state *state = IPV4LL_STATE(astate->iface); 177 178 state->conflicts = 0; 179 #ifdef KERNEL_RFC5227 180 arp_free(astate); 181 #endif 182 } 183 184 static void 185 ipv4ll_arpfree(struct arp_state *astate) 186 { 187 struct ipv4ll_state *state; 188 189 state = IPV4LL_STATE(astate->iface); 190 if (state != NULL && state->arp == astate) 191 state->arp = NULL; 192 } 193 194 static void 195 ipv4ll_not_found(struct interface *ifp) 196 { 197 struct ipv4ll_state *state; 198 struct ipv4_addr *ia; 199 #ifdef KERNEL_RFC5227 200 struct arp_state *astate; 201 #endif 202 203 state = IPV4LL_STATE(ifp); 204 assert(state != NULL); 205 206 ia = ipv4_iffindaddr(ifp, &state->pickedaddr, &inaddr_llmask); 207 #ifdef IN_IFF_NOTREADY 208 if (ia == NULL || ia->addr_flags & IN_IFF_NOTREADY) 209 #endif 210 loginfox("%s: using IPv4LL address %s", 211 ifp->name, inet_ntoa(state->pickedaddr)); 212 if (ia == NULL) { 213 if (ifp->ctx->options & DHCPCD_TEST) 214 goto test; 215 ia = ipv4_addaddr(ifp, &state->pickedaddr, 216 &inaddr_llmask, &inaddr_llbcast, 217 DHCP_INFINITE_LIFETIME, DHCP_INFINITE_LIFETIME); 218 } 219 if (ia == NULL) 220 return; 221 #ifdef IN_IFF_NOTREADY 222 if (ia->addr_flags & IN_IFF_NOTREADY) 223 return; 224 logdebugx("%s: DAD completed for %s", ifp->name, ia->saddr); 225 #endif 226 test: 227 state->addr = ia; 228 state->down = false; 229 if (ifp->ctx->options & DHCPCD_TEST) { 230 script_runreason(ifp, "TEST"); 231 eloop_exit(ifp->ctx->eloop, EXIT_SUCCESS); 232 return; 233 } 234 rt_build(ifp->ctx, AF_INET); 235 #ifdef KERNEL_RFC5227 236 astate = arp_new(ifp, &ia->addr); 237 if (astate != NULL) { 238 astate->announced_cb = ipv4ll_announced_arp; 239 astate->free_cb = ipv4ll_arpfree; 240 arp_announce(astate); 241 } 242 #else 243 arp_announce(state->arp); 244 #endif 245 script_runreason(ifp, "IPV4LL"); 246 dhcpcd_daemonise(ifp->ctx); 247 } 248 249 static void 250 ipv4ll_startifp(void *arg) 251 { 252 struct interface *ifp = arg; 253 struct ipv4ll_state *state; 254 255 state = IPV4LL_STATE(ifp); 256 ipv4ll_start1(ifp, state->arp); 257 } 258 259 static void 260 ipv4ll_found(struct interface *ifp) 261 { 262 struct ipv4ll_state *state = IPV4LL_STATE(ifp); 263 264 arp_cancel(state->arp); 265 if (++state->conflicts == MAX_CONFLICTS) 266 logerr("%s: failed to acquire an IPv4LL address", 267 ifp->name); 268 eloop_timeout_add_sec(ifp->ctx->eloop, 269 state->conflicts >= MAX_CONFLICTS ? 270 RATE_LIMIT_INTERVAL : PROBE_WAIT, 271 ipv4ll_startifp, ifp); 272 } 273 274 static void 275 ipv4ll_defend_failed(struct interface *ifp) 276 { 277 struct ipv4ll_state *state = IPV4LL_STATE(ifp); 278 279 ipv4_deladdr(state->addr, 1); 280 state->down = true; 281 state->addr = NULL; 282 rt_build(ifp->ctx, AF_INET); 283 script_runreason(ifp, "IPV4LL"); 284 ipv4ll_start1(ifp, state->arp); 285 } 286 287 #ifndef KERNEL_RFC5227 288 static void 289 ipv4ll_not_found_arp(struct arp_state *astate) 290 { 291 struct interface *ifp; 292 struct ipv4ll_state *state; 293 294 assert(astate != NULL); 295 assert(astate->iface != NULL); 296 297 ifp = astate->iface; 298 state = IPV4LL_STATE(ifp); 299 assert(state != NULL); 300 assert(state->arp == astate); 301 ipv4ll_not_found(ifp); 302 } 303 304 static void 305 ipv4ll_found_arp(struct arp_state *astate, __unused const struct arp_msg *amsg) 306 { 307 struct interface *ifp = astate->iface; 308 struct ipv4ll_state *state = IPV4LL_STATE(ifp); 309 310 assert(state->arp == astate); 311 ipv4ll_found(ifp); 312 } 313 314 static void 315 ipv4ll_defend_failed_arp(struct arp_state *astate) 316 { 317 struct ipv4ll_state *state = IPV4LL_STATE(astate->iface); 318 319 assert(state->arp == astate); 320 ipv4ll_defend_failed(astate->iface); 321 } 322 #endif 323 324 static void 325 ipv4ll_start1(struct interface *ifp, struct arp_state *astate) 326 { 327 struct ipv4ll_state *state; 328 struct ipv4_addr *ia; 329 bool repick; 330 331 assert(ifp != NULL); 332 if ((state = IPV4LL_STATE(ifp)) == NULL) { 333 ifp->if_data[IF_DATA_IPV4LL] = calloc(1, sizeof(*state)); 334 if ((state = IPV4LL_STATE(ifp)) == NULL) { 335 logerr(__func__); 336 return; 337 } 338 } 339 340 /* RFC 3927 Section 2.1 states that the random number generator 341 * SHOULD be seeded with a value derived from persistent information 342 * such as the IEEE 802 MAC address so that it usually picks 343 * the same address without persistent storage. */ 344 if (!state->seeded) { 345 unsigned int seed; 346 char *orig; 347 348 if (sizeof(seed) > ifp->hwlen) { 349 seed = 0; 350 memcpy(&seed, ifp->hwaddr, ifp->hwlen); 351 } else 352 memcpy(&seed, ifp->hwaddr + ifp->hwlen - sizeof(seed), 353 sizeof(seed)); 354 /* coverity[dont_call] */ 355 orig = initstate(seed, 356 state->randomstate, sizeof(state->randomstate)); 357 358 /* Save the original state. */ 359 if (ifp->ctx->randomstate == NULL) 360 ifp->ctx->randomstate = orig; 361 362 /* Set back the original state until we need the seeded one. */ 363 setstate(ifp->ctx->randomstate); 364 state->seeded = true; 365 } 366 367 #ifndef KERNEL_RFC5227 368 if (astate == NULL) { 369 if (state->arp != NULL) 370 return; 371 if ((astate = arp_new(ifp, NULL)) == NULL) 372 return; 373 astate->found_cb = ipv4ll_found_arp; 374 astate->not_found_cb = ipv4ll_not_found_arp; 375 astate->announced_cb = ipv4ll_announced_arp; 376 astate->defend_failed_cb = ipv4ll_defend_failed_arp; 377 astate->free_cb = ipv4ll_arpfree; 378 state->arp = astate; 379 } else 380 assert(state->arp == astate); 381 #else 382 UNUSED(astate); 383 #endif 384 385 state->down = true; 386 387 /* Find the previosuly used address. */ 388 if (state->pickedaddr.s_addr != INADDR_ANY) 389 ia = ipv4_iffindaddr(ifp, &state->pickedaddr, NULL); 390 else 391 ia = NULL; 392 393 /* Find an existing IPv4LL address and ensure we can work with it. */ 394 if (ia == NULL) 395 ia = ipv4_iffindlladdr(ifp); 396 397 repick = false; 398 #ifdef IN_IFF_DUPLICATED 399 if (ia != NULL && ia->addr_flags & IN_IFF_DUPLICATED) { 400 state->pickedaddr = ia->addr; /* So it's not picked again. */ 401 repick = true; 402 ipv4_deladdr(ia, 0); 403 ia = NULL; 404 } 405 #endif 406 407 state->addr = ia; 408 if (ia != NULL) { 409 state->pickedaddr = ia->addr; 410 #ifndef KERNEL_RFC5227 411 astate->addr = ia->addr; 412 #endif 413 #ifdef IN_IFF_TENTATIVE 414 if (ia->addr_flags & (IN_IFF_TENTATIVE | IN_IFF_DETACHED)) { 415 loginfox("%s: waiting for DAD to complete on %s", 416 ifp->name, inet_ntoa(ia->addr)); 417 return; 418 } 419 #endif 420 #ifdef IN_IFF_DUPLICATED 421 loginfox("%s: using IPv4LL address %s", ifp->name, ia->saddr); 422 #endif 423 ipv4ll_not_found(ifp); 424 return; 425 } 426 427 loginfox("%s: probing for an IPv4LL address", ifp->name); 428 if (repick || state->pickedaddr.s_addr == INADDR_ANY) 429 state->pickedaddr.s_addr = ipv4ll_pickaddr(ifp); 430 #ifndef KERNEL_RFC5227 431 astate->addr = state->pickedaddr; 432 #endif 433 #ifdef IN_IFF_DUPLICATED 434 ipv4ll_not_found(ifp); 435 #else 436 arp_probe(astate); 437 #endif 438 } 439 440 void 441 ipv4ll_start(void *arg) 442 { 443 444 ipv4ll_start1(arg, NULL); 445 } 446 447 static void 448 ipv4ll_freearp(struct interface *ifp) 449 { 450 struct ipv4ll_state *state; 451 452 state = IPV4LL_STATE(ifp); 453 if (state == NULL || state->arp == NULL) 454 return; 455 456 eloop_timeout_delete(ifp->ctx->eloop, NULL, state->arp); 457 arp_free(state->arp); 458 } 459 460 void 461 ipv4ll_drop(struct interface *ifp) 462 { 463 struct ipv4ll_state *state; 464 bool dropped = false; 465 struct ipv4_state *istate; 466 467 assert(ifp != NULL); 468 469 ipv4ll_freearp(ifp); 470 471 if ((ifp->options->options & DHCPCD_NODROP) == DHCPCD_NODROP) 472 return; 473 474 state = IPV4LL_STATE(ifp); 475 if (state && state->addr != NULL) { 476 ipv4_deladdr(state->addr, 1); 477 state->addr = NULL; 478 dropped = true; 479 } 480 481 /* Free any other link local addresses that might exist. */ 482 if ((istate = IPV4_STATE(ifp)) != NULL) { 483 struct ipv4_addr *ia, *ian; 484 485 TAILQ_FOREACH_SAFE(ia, &istate->addrs, next, ian) { 486 if (IN_LINKLOCAL(ntohl(ia->addr.s_addr))) { 487 ipv4_deladdr(ia, 0); 488 dropped = true; 489 } 490 } 491 } 492 493 if (dropped) { 494 rt_build(ifp->ctx, AF_INET); 495 script_runreason(ifp, "IPV4LL"); 496 } 497 } 498 499 void 500 ipv4ll_reset(struct interface *ifp) 501 { 502 struct ipv4ll_state *state = IPV4LL_STATE(ifp); 503 504 if (state == NULL) 505 return; 506 state->pickedaddr.s_addr = INADDR_ANY; 507 state->seeded = false; 508 } 509 510 void 511 ipv4ll_free(struct interface *ifp) 512 { 513 514 assert(ifp != NULL); 515 516 ipv4ll_freearp(ifp); 517 free(IPV4LL_STATE(ifp)); 518 ifp->if_data[IF_DATA_IPV4LL] = NULL; 519 } 520 521 /* This may cause issues in BSD systems, where running as a single dhcpcd 522 * daemon would solve this issue easily. */ 523 #ifdef HAVE_ROUTE_METRIC 524 int 525 ipv4ll_recvrt(__unused int cmd, const struct rt *rt) 526 { 527 struct dhcpcd_ctx *ctx; 528 struct interface *ifp; 529 530 /* Only interested in default route changes. */ 531 if (sa_is_unspecified(&rt->rt_dest)) 532 return 0; 533 534 /* If any interface is running IPv4LL, rebuild our routing table. */ 535 ctx = rt->rt_ifp->ctx; 536 TAILQ_FOREACH(ifp, ctx->ifaces, next) { 537 if (IPV4LL_STATE_RUNNING(ifp)) { 538 rt_build(ctx, AF_INET); 539 break; 540 } 541 } 542 543 return 0; 544 } 545 #endif 546 547 void 548 ipv4ll_handleifa(int cmd, struct ipv4_addr *ia, pid_t pid) 549 { 550 struct interface *ifp; 551 struct ipv4ll_state *state; 552 553 ifp = ia->iface; 554 state = IPV4LL_STATE(ifp); 555 if (state == NULL) 556 return; 557 558 if (cmd == RTM_DELADDR && 559 state->addr != NULL && 560 IN_ARE_ADDR_EQUAL(&state->addr->addr, &ia->addr)) 561 { 562 loginfox("%s: pid %d deleted IP address %s", 563 ifp->name, pid, ia->saddr); 564 ipv4ll_defend_failed(ifp); 565 return; 566 } 567 568 #ifdef IN_IFF_DUPLICATED 569 if (cmd != RTM_NEWADDR) 570 return; 571 if (!IN_ARE_ADDR_EQUAL(&state->pickedaddr, &ia->addr)) 572 return; 573 if (!(ia->addr_flags & IN_IFF_NOTUSEABLE)) 574 ipv4ll_not_found(ifp); 575 else if (ia->addr_flags & IN_IFF_DUPLICATED) { 576 logerrx("%s: DAD detected %s", ifp->name, ia->saddr); 577 ipv4_deladdr(state->addr, 1); 578 ipv4ll_found(ifp); 579 } 580 #endif 581 } 582