src/libsystemd-network/sd-radv.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2017 Intel Corporation. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <netinet/icmp6.h>
  21 #include <netinet/in.h>
  22 #include <arpa/inet.h>
  23 #include <linux/in6.h>
  24
  25 #include "sd-radv.h"
  26
  27 #include "macro.h"
  28 #include "alloc-util.h"
  29 #include "fd-util.h"
  30 #include "icmp6-util.h"
  31 #include "in-addr-util.h"
  32 #include "radv-internal.h"
  33 #include "socket-util.h"
  34 #include "string-util.h"
  35 #include "util.h"
  36 #include "random-util.h"
  37
  38 _public_ int sd_radv_new(sd_radv **ret) {
  39         _cleanup_(sd_radv_unrefp) sd_radv *ra = NULL;
  40
  41         assert_return(ret, -EINVAL);
  42
  43         ra = new0(sd_radv, 1);
  44         if (!ra)
  45                 return -ENOMEM;
  46
  47         ra->n_ref = 1;
  48         ra->fd = -1;
  49
  50         LIST_HEAD_INIT(ra->prefixes);
  51
  52         *ret = ra;
  53         ra = NULL;
  54
  55         return 0;
  56 }
  57
  58 _public_ int sd_radv_attach_event(sd_radv *ra, sd_event *event, int64_t priority) {
  59         int r;
  60
  61         assert_return(ra, -EINVAL);
  62         assert_return(!ra->event, -EBUSY);
  63
  64         if (event)
  65                 ra->event = sd_event_ref(event);
  66         else {
  67                 r = sd_event_default(&ra->event);
  68                 if (r < 0)
  69                         return 0;
  70         }
  71
  72         ra->event_priority = priority;
  73
  74         return 0;
  75 }
  76
  77 _public_ int sd_radv_detach_event(sd_radv *ra) {
  78
  79         assert_return(ra, -EINVAL);
  80
  81         ra->event = sd_event_unref(ra->event);
  82         return 0;
  83 }
  84
  85 _public_ sd_event *sd_radv_get_event(sd_radv *ra) {
  86         assert_return(ra, NULL);
  87
  88         return ra->event;
  89 }
  90
  91 static void radv_reset(sd_radv *ra) {
  92
  93         ra->timeout_event_source =
  94                 sd_event_source_unref(ra->timeout_event_source);
  95
  96         ra->recv_event_source =
  97                 sd_event_source_unref(ra->recv_event_source);
  98
  99         ra->ra_sent = 0;
 100 }
 101
 102 _public_ sd_radv *sd_radv_ref(sd_radv *ra) {
 103         if (!ra)
 104                 return NULL;
 105
 106         assert(ra->n_ref > 0);
 107         ra->n_ref++;
 108
 109         return ra;
 110 }
 111
 112 _public_ sd_radv *sd_radv_unref(sd_radv *ra) {
 113         if (!ra)
 114                 return NULL;
 115
 116         assert(ra->n_ref > 0);
 117         ra->n_ref--;
 118
 119         if (ra->n_ref > 0)
 120                 return NULL;
 121
 122         while (ra->prefixes) {
 123                 sd_radv_prefix *p = ra->prefixes;
 124
 125                 LIST_REMOVE(prefix, ra->prefixes, p);
 126                 sd_radv_prefix_unref(p);
 127         }
 128
 129         radv_reset(ra);
 130
 131         sd_radv_detach_event(ra);
 132         return mfree(ra);
 133 }
 134
 135 static int radv_send(sd_radv *ra, const struct in6_addr *dst,
 136                      const uint32_t router_lifetime) {
 137         static const struct ether_addr mac_zero = {};
 138         sd_radv_prefix *p;
 139         struct sockaddr_in6 dst_addr = {
 140                 .sin6_family = AF_INET6,
 141                 .sin6_addr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
 142         };
 143         struct nd_router_advert adv = {};
 144         struct {
 145                 struct nd_opt_hdr opthdr;
 146                 struct ether_addr slladdr;
 147         } _packed_ opt_mac = {
 148                 .opthdr = {
 149                         .nd_opt_type = ND_OPT_SOURCE_LINKADDR,
 150                         .nd_opt_len = (sizeof(struct nd_opt_hdr) +
 151                                        sizeof(struct ether_addr) - 1) /8 + 1,
 152                 },
 153         };
 154         struct nd_opt_mtu opt_mtu =  {
 155                 .nd_opt_mtu_type = ND_OPT_MTU,
 156                 .nd_opt_mtu_len = 1,
 157         };
 158         /* Reserve iov space for RA header, linkaddr, MTU + N prefixes */
 159         struct iovec iov[3 + ra->n_prefixes];
 160         struct msghdr msg = {
 161                 .msg_name = &dst_addr,
 162                 .msg_namelen = sizeof(dst_addr),
 163                 .msg_iov = iov,
 164         };
 165
 166         if (dst && !in_addr_is_null(AF_INET6, (union in_addr_union*) dst))
 167                 dst_addr.sin6_addr = *dst;
 168
 169         adv.nd_ra_type = ND_ROUTER_ADVERT;
 170         adv.nd_ra_curhoplimit = ra->hop_limit;
 171         adv.nd_ra_flags_reserved = ra->flags;
 172         adv.nd_ra_router_lifetime = htobe16(router_lifetime);
 173         iov[msg.msg_iovlen].iov_base = &adv;
 174         iov[msg.msg_iovlen].iov_len = sizeof(adv);
 175         msg.msg_iovlen++;
 176
 177         /* MAC address is optional, either because the link does not use L2
 178            addresses or load sharing is desired. See RFC 4861, Section 4.2 */
 179         if (memcmp(&mac_zero, &ra->mac_addr, sizeof(mac_zero))) {
 180                 opt_mac.slladdr = ra->mac_addr;
 181                 iov[msg.msg_iovlen].iov_base = &opt_mac;
 182                 iov[msg.msg_iovlen].iov_len = sizeof(opt_mac);
 183                 msg.msg_iovlen++;
 184         }
 185
 186         if (ra->mtu) {
 187                 opt_mtu.nd_opt_mtu_mtu = htobe32(ra->mtu);
 188                 iov[msg.msg_iovlen].iov_base = &opt_mtu;
 189                 iov[msg.msg_iovlen].iov_len = sizeof(opt_mtu);
 190                 msg.msg_iovlen++;
 191         }
 192
 193         LIST_FOREACH(prefix, p, ra->prefixes) {
 194                 iov[msg.msg_iovlen].iov_base = &p->opt;
 195                 iov[msg.msg_iovlen].iov_len = sizeof(p->opt);
 196                 msg.msg_iovlen++;
 197         }
 198
 199         if (sendmsg(ra->fd, &msg, 0) < 0)
 200                 return -errno;
 201
 202         return 0;
 203 }
 204
 205 static int radv_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 206         sd_radv *ra = userdata;
 207         _cleanup_free_ char *addr = NULL;
 208         struct in6_addr src;
 209         triple_timestamp timestamp;
 210         int r;
 211         ssize_t buflen;
 212         _cleanup_free_ char *buf = NULL;
 213
 214         assert(s);
 215         assert(ra);
 216         assert(ra->event);
 217
 218         buflen = next_datagram_size_fd(fd);
 219
 220         if ((unsigned) buflen < sizeof(struct nd_router_solicit))
 221                 return log_radv("Too short packet received");
 222
 223         buf = new0(char, buflen);
 224         if (!buf)
 225                 return 0;
 226
 227         r = icmp6_receive(fd, buf, buflen, &src, &timestamp);
 228         if (r < 0) {
 229                 switch (r) {
 230                 case -EADDRNOTAVAIL:
 231                         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &src, &addr);
 232                         log_radv("Received RS from non-link-local address %s. Ignoring", addr);
 233                         break;
 234
 235                 case -EMULTIHOP:
 236                         log_radv("Received RS with invalid hop limit. Ignoring.");
 237                         break;
 238
 239                 case -EPFNOSUPPORT:
 240                         log_radv("Received invalid source address from ICMPv6 socket. Ignoring.");
 241                         break;
 242
 243                 default:
 244                         log_radv_warning_errno(r, "Error receiving from ICMPv6 socket: %m");
 245                         break;
 246                 }
 247
 248                 return 0;
 249         }
 250
 251         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &src, &addr);
 252
 253         r = radv_send(ra, &src, ra->lifetime);
 254         if (r < 0)
 255                 log_radv_warning_errno(r, "Unable to send solicited Router Advertisment to %s: %m", addr);
 256         else
 257                 log_radv("Sent solicited Router Advertisement to %s", addr);
 258
 259         return 0;
 260 }
 261
 262 static usec_t radv_compute_timeout(usec_t min, usec_t max) {
 263         assert_return(min <= max, SD_RADV_DEFAULT_MIN_TIMEOUT_USEC);
 264
 265         return min + (random_u32() % (max - min));
 266 }
 267
 268 static int radv_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
 269         int r;
 270         sd_radv *ra = userdata;
 271         usec_t min_timeout = SD_RADV_DEFAULT_MIN_TIMEOUT_USEC;
 272         usec_t max_timeout = SD_RADV_DEFAULT_MAX_TIMEOUT_USEC;
 273         usec_t time_now, timeout;
 274         char time_string[FORMAT_TIMESPAN_MAX];
 275
 276         assert(s);
 277         assert(ra);
 278         assert(ra->event);
 279
 280         ra->timeout_event_source = sd_event_source_unref(ra->timeout_event_source);
 281
 282         r = sd_event_now(ra->event, clock_boottime_or_monotonic(), &time_now);
 283         if (r < 0)
 284                 goto fail;
 285
 286         r = radv_send(ra, NULL, ra->lifetime);
 287         if (r < 0)
 288                 log_radv_warning_errno(r, "Unable to send Router Advertisement: %m");
 289
 290         /* RFC 4861, Section 6.2.4, sending initial Router Advertisements */
 291         if (ra->ra_sent < SD_RADV_MAX_INITIAL_RTR_ADVERTISEMENTS) {
 292                 max_timeout = SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC;
 293                 min_timeout = SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC / 3;
 294         }
 295
 296         timeout = radv_compute_timeout(min_timeout, max_timeout);
 297
 298         log_radv("Next Router Advertisement in %s",
 299                  format_timespan(time_string, FORMAT_TIMESPAN_MAX,
 300                                  timeout, USEC_PER_SEC));
 301
 302         r = sd_event_add_time(ra->event, &ra->timeout_event_source,
 303                               clock_boottime_or_monotonic(),
 304                               time_now + timeout, MSEC_PER_SEC,
 305                               radv_timeout, ra);
 306         if (r < 0)
 307                 goto fail;
 308
 309         r = sd_event_source_set_priority(ra->timeout_event_source,
 310                                          ra->event_priority);
 311         if (r < 0)
 312                 goto fail;
 313
 314         r = sd_event_source_set_description(ra->timeout_event_source,
 315                                             "radv-timeout");
 316         if (r < 0)
 317                 goto fail;
 318
 319         ra->ra_sent++;
 320
 321 fail:
 322         if (r < 0)
 323                 sd_radv_stop(ra);
 324
 325         return 0;
 326 }
 327
 328 _public_ int sd_radv_stop(sd_radv *ra) {
 329         int r;
 330
 331         assert_return(ra, -EINVAL);
 332
 333         log_radv("Stopping IPv6 Router Advertisement daemon");
 334
 335         /* RFC 4861, Section 6.2.5, send at least one Router Advertisement
 336            with zero lifetime  */
 337         r = radv_send(ra, NULL, 0);
 338         if (r < 0)
 339                 log_radv_warning_errno(r, "Unable to send last Router Advertisement with router lifetime set to zero: %m");
 340
 341         radv_reset(ra);
 342         ra->fd = safe_close(ra->fd);
 343         ra->state = SD_RADV_STATE_IDLE;
 344
 345         return 0;
 346 }
 347
 348 _public_ int sd_radv_start(sd_radv *ra) {
 349         int r = 0;
 350
 351         assert_return(ra, -EINVAL);
 352         assert_return(ra->event, -EINVAL);
 353         assert_return(ra->ifindex > 0, -EINVAL);
 354
 355         if (ra->state != SD_RADV_STATE_IDLE)
 356                 return 0;
 357
 358         r = sd_event_add_time(ra->event, &ra->timeout_event_source,
 359                               clock_boottime_or_monotonic(), 0, 0,
 360                               radv_timeout, ra);
 361         if (r < 0)
 362                 goto fail;
 363
 364         r = sd_event_source_set_priority(ra->timeout_event_source,
 365                                          ra->event_priority);
 366         if (r < 0)
 367                 goto fail;
 368
 369         (void) sd_event_source_set_description(ra->timeout_event_source,
 370                                                "radv-timeout");
 371
 372         r = icmp6_bind_router_advertisement(ra->ifindex);
 373         if (r < 0)
 374                 goto fail;
 375
 376         ra->fd = r;
 377
 378         r = sd_event_add_io(ra->event, &ra->recv_event_source, ra->fd, EPOLLIN, radv_recv, ra);
 379         if (r < 0)
 380                 goto fail;
 381
 382         r = sd_event_source_set_priority(ra->recv_event_source, ra->event_priority);
 383         if (r < 0)
 384                 goto fail;
 385
 386         (void) sd_event_source_set_description(ra->recv_event_source, "radv-receive-message");
 387
 388         ra->state = SD_RADV_STATE_ADVERTISING;
 389
 390         log_radv("Started IPv6 Router Advertisement daemon");
 391
 392         return 0;
 393
 394  fail:
 395         radv_reset(ra);
 396
 397         return r;
 398 }
 399
 400 _public_ int sd_radv_set_ifindex(sd_radv *ra, int ifindex) {
 401         assert_return(ra, -EINVAL);
 402         assert_return(ifindex >= -1, -EINVAL);
 403
 404         if (ra->state != SD_RADV_STATE_IDLE)
 405                 return -EBUSY;
 406
 407         ra->ifindex = ifindex;
 408
 409         return 0;
 410 }
 411
 412 _public_ int sd_radv_set_mac(sd_radv *ra, const struct ether_addr *mac_addr) {
 413         assert_return(ra, -EINVAL);
 414
 415         if (ra->state != SD_RADV_STATE_IDLE)
 416                 return -EBUSY;
 417
 418         if (mac_addr)
 419                 ra->mac_addr = *mac_addr;
 420         else
 421                 zero(ra->mac_addr);
 422
 423         return 0;
 424 }
 425
 426 _public_ int sd_radv_set_mtu(sd_radv *ra, uint32_t mtu) {
 427         assert_return(ra, -EINVAL);
 428         assert_return(mtu >= 1280, -EINVAL);
 429
 430         if (ra->state != SD_RADV_STATE_IDLE)
 431                 return -EBUSY;
 432
 433         ra->mtu = mtu;
 434
 435         return 0;
 436 }
 437
 438 _public_ int sd_radv_set_hop_limit(sd_radv *ra, uint8_t hop_limit) {
 439         assert_return(ra, -EINVAL);
 440
 441         if (ra->state != SD_RADV_STATE_IDLE)
 442                 return -EBUSY;
 443
 444         ra->hop_limit = hop_limit;
 445
 446         return 0;
 447 }
 448
 449 _public_ int sd_radv_set_router_lifetime(sd_radv *ra, uint32_t router_lifetime) {
 450         assert_return(ra, -EINVAL);
 451
 452         if (ra->state != SD_RADV_STATE_IDLE)
 453                 return -EBUSY;
 454
 455         /* RFC 4191, Section 2.2, "...If the Router Lifetime is zero, the
 456            preference value MUST be set to (00) by the sender..." */
 457         if (router_lifetime == 0 &&
 458             (ra->flags & (0x3 << 3)) != (SD_NDISC_PREFERENCE_MEDIUM << 3))
 459                 return -ETIME;
 460
 461         ra->lifetime = router_lifetime;
 462
 463         return 0;
 464 }
 465
 466 _public_ int sd_radv_set_managed_information(sd_radv *ra, int managed) {
 467         assert_return(ra, -EINVAL);
 468
 469         if (ra->state != SD_RADV_STATE_IDLE)
 470                 return -EBUSY;
 471
 472         SET_FLAG(ra->flags, ND_RA_FLAG_MANAGED, managed);
 473
 474         return 0;
 475 }
 476
 477 _public_ int sd_radv_set_other_information(sd_radv *ra, int other) {
 478         assert_return(ra, -EINVAL);
 479
 480         if (ra->state != SD_RADV_STATE_IDLE)
 481                 return -EBUSY;
 482
 483         SET_FLAG(ra->flags, ND_RA_FLAG_OTHER, other);
 484
 485         return 0;
 486 }
 487
 488 _public_ int sd_radv_set_preference(sd_radv *ra, unsigned preference) {
 489         int r = 0;
 490
 491         assert_return(ra, -EINVAL);
 492         assert_return(IN_SET(preference,
 493                              SD_NDISC_PREFERENCE_LOW,
 494                              SD_NDISC_PREFERENCE_MEDIUM,
 495                              SD_NDISC_PREFERENCE_HIGH), -EINVAL);
 496
 497         ra->flags = (ra->flags & ~(0x3 << 3)) | (preference << 3);
 498
 499         return r;
 500 }
 501
 502 _public_ int sd_radv_add_prefix(sd_radv *ra, sd_radv_prefix *p) {
 503         sd_radv_prefix *cur;
 504         _cleanup_free_ char *addr_p = NULL;
 505
 506         assert_return(ra, -EINVAL);
 507
 508         if (!p)
 509                 return -EINVAL;
 510
 511         LIST_FOREACH(prefix, cur, ra->prefixes) {
 512                 int r;
 513
 514                 r = in_addr_prefix_intersect(AF_INET6,
 515                                              (union in_addr_union*) &cur->opt.in6_addr,
 516                                              cur->opt.prefixlen,
 517                                              (union in_addr_union*) &p->opt.in6_addr,
 518                                              p->opt.prefixlen);
 519                 if (r > 0) {
 520                         _cleanup_free_ char *addr_cur = NULL;
 521
 522                         (void) in_addr_to_string(AF_INET6,
 523                                                  (union in_addr_union*) &cur->opt.in6_addr,
 524                                                  &addr_cur);
 525                         (void) in_addr_to_string(AF_INET6,
 526                                                  (union in_addr_union*) &p->opt.in6_addr,
 527                                                  &addr_p);
 528
 529                         log_radv("IPv6 prefix %s/%u already configured, ignoring %s/%u",
 530                                  addr_cur, cur->opt.prefixlen,
 531                                  addr_p, p->opt.prefixlen);
 532
 533                         return -EEXIST;
 534                 }
 535         }
 536
 537         p = sd_radv_prefix_ref(p);
 538
 539         LIST_APPEND(prefix, ra->prefixes, p);
 540
 541         ra->n_prefixes++;
 542
 543         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &p->opt.in6_addr, &addr_p);
 544         log_radv("Added prefix %s/%d", addr_p, p->opt.prefixlen);
 545
 546         return 0;
 547 }
 548
 549 _public_ int sd_radv_prefix_new(sd_radv_prefix **ret) {
 550         _cleanup_(sd_radv_prefix_unrefp) sd_radv_prefix *p = NULL;
 551
 552         assert_return(ret, -EINVAL);
 553
 554         p = new0(sd_radv_prefix, 1);
 555         if (!p)
 556                 return -ENOMEM;
 557
 558         p->n_ref = 1;
 559
 560         p->opt.type = ND_OPT_PREFIX_INFORMATION;
 561         p->opt.length = (sizeof(p->opt) - 1) /8 + 1;
 562
 563         p->opt.prefixlen = 64;
 564
 565         /* RFC 4861, Section 6.2.1 */
 566         SET_FLAG(p->opt.flags, ND_OPT_PI_FLAG_ONLINK, true);
 567         SET_FLAG(p->opt.flags, ND_OPT_PI_FLAG_AUTO, true);
 568         p->opt.preferred_lifetime = htobe32(604800);
 569         p->opt.valid_lifetime = htobe32(2592000);
 570
 571         LIST_INIT(prefix, p);
 572
 573         *ret = p;
 574         p = NULL;
 575
 576         return 0;
 577 }
 578
 579 _public_ sd_radv_prefix *sd_radv_prefix_ref(sd_radv_prefix *p) {
 580         if (!p)
 581                 return NULL;
 582
 583         assert(p->n_ref > 0);
 584         p->n_ref++;
 585
 586         return p;
 587 }
 588
 589 _public_ sd_radv_prefix *sd_radv_prefix_unref(sd_radv_prefix *p) {
 590         if (!p)
 591                 return NULL;
 592
 593         assert(p->n_ref > 0);
 594         p->n_ref--;
 595
 596         if (p->n_ref > 0)
 597                 return NULL;
 598
 599         return mfree(p);
 600 }
 601
 602 _public_ int sd_radv_prefix_set_prefix(sd_radv_prefix *p, struct in6_addr *in6_addr,
 603                                        unsigned char prefixlen) {
 604         assert_return(p, -EINVAL);
 605         assert_return(in6_addr, -EINVAL);
 606
 607         if (prefixlen < 3 || prefixlen > 128)
 608                 return -EINVAL;
 609
 610         if (prefixlen > 64)
 611                 /* unusual but allowed, log it */
 612                 log_radv("Unusual prefix length %d greater than 64", prefixlen);
 613
 614         p->opt.in6_addr = *in6_addr;
 615         p->opt.prefixlen = prefixlen;
 616
 617         return 0;
 618 }
 619
 620 _public_ int sd_radv_prefix_set_onlink(sd_radv_prefix *p, int onlink) {
 621         assert_return(p, -EINVAL);
 622
 623         SET_FLAG(p->opt.flags, ND_OPT_PI_FLAG_ONLINK, onlink);
 624
 625         return 0;
 626 }
 627
 628 _public_ int sd_radv_prefix_set_address_autoconfiguration(sd_radv_prefix *p,
 629                                                           int address_autoconfiguration) {
 630         assert_return(p, -EINVAL);
 631
 632         SET_FLAG(p->opt.flags, ND_OPT_PI_FLAG_AUTO, address_autoconfiguration);
 633
 634         return 0;
 635 }
 636
 637 _public_ int sd_radv_prefix_set_valid_lifetime(sd_radv_prefix *p,
 638                                                uint32_t valid_lifetime) {
 639         assert_return(p, -EINVAL);
 640
 641         p->opt.valid_lifetime = htobe32(valid_lifetime);
 642
 643         return 0;
 644 }
 645
 646 _public_ int sd_radv_prefix_set_preferred_lifetime(sd_radv_prefix *p,
 647                                                    uint32_t preferred_lifetime) {
 648         assert_return(p, -EINVAL);
 649
 650         p->opt.preferred_lifetime = htobe32(preferred_lifetime);
 651
 652         return 0;
 653 }