src/libsystemd-network/sd-ipv4ll.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2014 Axis Communications AB. 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 <stdlib.h>
  21 #include <errno.h>
  22 #include <string.h>
  23 #include <stdio.h>
  24 #include <arpa/inet.h>
  25
  26 #include "util.h"
  27 #include "siphash24.h"
  28 #include "list.h"
  29 #include "refcnt.h"
  30
  31 #include "ipv4ll-internal.h"
  32 #include "sd-ipv4ll.h"
  33
  34 /* Constants from the RFC */
  35 #define PROBE_WAIT 1
  36 #define PROBE_NUM 3
  37 #define PROBE_MIN 1
  38 #define PROBE_MAX 2
  39 #define ANNOUNCE_WAIT 2
  40 #define ANNOUNCE_NUM 2
  41 #define ANNOUNCE_INTERVAL 2
  42 #define MAX_CONFLICTS 10
  43 #define RATE_LIMIT_INTERVAL 60
  44 #define DEFEND_INTERVAL 10
  45
  46 #define IPV4LL_NETWORK 0xA9FE0000L
  47 #define IPV4LL_NETMASK 0xFFFF0000L
  48
  49 typedef enum IPv4LLTrigger{
  50         IPV4LL_TRIGGER_NULL,
  51         IPV4LL_TRIGGER_PACKET,
  52         IPV4LL_TRIGGER_TIMEOUT,
  53         _IPV4LL_TRIGGER_MAX,
  54         _IPV4LL_TRIGGER_INVALID = -1
  55 } IPv4LLTrigger;
  56
  57 typedef enum IPv4LLState {
  58         IPV4LL_STATE_INIT,
  59         IPV4LL_STATE_WAITING_PROBE,
  60         IPV4LL_STATE_PROBING,
  61         IPV4LL_STATE_WAITING_ANNOUNCE,
  62         IPV4LL_STATE_ANNOUNCING,
  63         IPV4LL_STATE_RUNNING,
  64         IPV4LL_STATE_STOPPED,
  65         _IPV4LL_STATE_MAX,
  66         _IPV4LL_STATE_INVALID = -1
  67 } IPv4LLState;
  68
  69 struct sd_ipv4ll {
  70         RefCount n_ref;
  71
  72         IPv4LLState state;
  73         int index;
  74         int fd;
  75         union sockaddr_union link;
  76         int iteration;
  77         int conflict;
  78         sd_event_source *receive_message;
  79         sd_event_source *timer;
  80         usec_t next_wakeup;
  81         usec_t defend_window;
  82         int next_wakeup_valid;
  83         be32_t address;
  84         struct random_data *random_data;
  85         char *random_data_state;
  86         /* External */
  87         be32_t claimed_address;
  88         struct ether_addr mac_addr;
  89         sd_event *event;
  90         int event_priority;
  91         sd_ipv4ll_cb_t cb;
  92         void* userdata;
  93 };
  94
  95 static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data);
  96
  97 static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) {
  98
  99         assert(ll);
 100         assert(st < _IPV4LL_STATE_MAX);
 101
 102         if (st == ll->state && !reset_counter) {
 103                 ll->iteration++;
 104         } else {
 105                 ll->state = st;
 106                 ll->iteration = 0;
 107         }
 108 }
 109
 110 static sd_ipv4ll *ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 111         assert(ll);
 112
 113         if (ll->cb) {
 114                 ll = sd_ipv4ll_ref(ll);
 115                 ll->cb(ll, event, ll->userdata);
 116                 ll = sd_ipv4ll_unref(ll);
 117         }
 118
 119         return ll;
 120 }
 121
 122 static sd_ipv4ll *ipv4ll_stop(sd_ipv4ll *ll, int event) {
 123         assert(ll);
 124
 125         ll->receive_message = sd_event_source_unref(ll->receive_message);
 126         ll->fd = safe_close(ll->fd);
 127
 128         ll->timer = sd_event_source_unref(ll->timer);
 129
 130         log_ipv4ll(ll, "STOPPED");
 131
 132         ll = ipv4ll_client_notify(ll, event);
 133
 134         if (ll) {
 135                 ll->claimed_address = 0;
 136                 ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
 137         }
 138
 139         return ll;
 140 }
 141
 142 static int ipv4ll_pick_address(sd_ipv4ll *ll, be32_t *address) {
 143         be32_t addr;
 144         int r;
 145         int32_t random;
 146
 147         assert(ll);
 148         assert(address);
 149         assert(ll->random_data);
 150
 151         do {
 152                 r = random_r(ll->random_data, &random);
 153                 if (r < 0)
 154                         return r;
 155                 addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
 156         } while (addr == ll->address ||
 157                 (ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
 158                 (ntohl(addr) & 0x0000FF00) == 0x0000 ||
 159                 (ntohl(addr) & 0x0000FF00) == 0xFF00);
 160
 161         *address = addr;
 162         return 0;
 163 }
 164
 165 static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) {
 166         sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
 167
 168         assert(ll);
 169
 170         ll->next_wakeup_valid = 0;
 171         ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL);
 172
 173         return 0;
 174 }
 175
 176 static void ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
 177         usec_t next_timeout = 0;
 178         usec_t time_now = 0;
 179
 180         assert(sec >= 0);
 181         assert(random_sec >= 0);
 182         assert(ll);
 183
 184         next_timeout = sec * USEC_PER_SEC;
 185
 186         if (random_sec)
 187                 next_timeout += random_u32() % (random_sec * USEC_PER_SEC);
 188
 189         if (sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now) < 0)
 190                 time_now = now(CLOCK_MONOTONIC);
 191
 192         ll->next_wakeup = time_now + next_timeout;
 193         ll->next_wakeup_valid = 1;
 194 }
 195
 196 static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
 197         assert(ll);
 198         assert(arp);
 199
 200         if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 &&
 201             memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0)
 202                 return true;
 203
 204         return false;
 205 }
 206
 207 static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
 208         assert(ll);
 209         assert(arp);
 210
 211         if (ipv4ll_arp_conflict(ll, arp))
 212                 return true;
 213
 214         if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 &&
 215             memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN))
 216                 return true;
 217
 218         return false;
 219 }
 220
 221 static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {
 222         struct ether_arp out_packet;
 223         int out_packet_ready = 0;
 224         int r = 0;
 225
 226         assert(ll);
 227         assert(trigger < _IPV4LL_TRIGGER_MAX);
 228
 229         if (ll->state == IPV4LL_STATE_INIT) {
 230
 231                 log_ipv4ll(ll, "PROBE");
 232                 ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
 233                 ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
 234
 235         } else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
 236                 (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) {
 237
 238                 /* Send a probe */
 239                 arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
 240                 out_packet_ready = 1;
 241                 ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0);
 242
 243                 ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
 244
 245         } else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) {
 246
 247                 /* Send the last probe */
 248                 arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
 249                 out_packet_ready = 1;
 250                 ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1);
 251
 252                 ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
 253
 254         } else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
 255                 (ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) {
 256
 257                 /* Send announcement packet */
 258                 arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
 259                 out_packet_ready = 1;
 260                 ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0);
 261
 262                 ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
 263
 264                 if (ll->iteration == 0) {
 265                         log_ipv4ll(ll, "ANNOUNCE");
 266                         ll->claimed_address = ll->address;
 267                         ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
 268                         if (!ll || ll->state == IPV4LL_STATE_STOPPED)
 269                                 goto out;
 270
 271                         ll->conflict = 0;
 272                 }
 273
 274         } else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT &&
 275                     ll->iteration >= ANNOUNCE_NUM-1)) {
 276
 277                 ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0);
 278                 ll->next_wakeup_valid = 0;
 279
 280         } else if (trigger == IPV4LL_TRIGGER_PACKET) {
 281
 282                 int conflicted = 0;
 283                 usec_t time_now;
 284                 struct ether_arp* in_packet = (struct ether_arp*)trigger_data;
 285
 286                 assert(in_packet);
 287
 288                 if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) {
 289
 290                         if (ipv4ll_arp_conflict(ll, in_packet)) {
 291
 292                                 r = sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now);
 293                                 if (r < 0)
 294                                         goto out;
 295
 296                                 /* Defend address */
 297                                 if (time_now > ll->defend_window) {
 298                                         ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC;
 299                                         arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
 300                                         out_packet_ready = 1;
 301                                 } else
 302                                         conflicted = 1;
 303                         }
 304
 305                 } else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE,
 306                                              IPV4LL_STATE_PROBING,
 307                                              IPV4LL_STATE_WAITING_ANNOUNCE)) {
 308
 309                         conflicted = ipv4ll_arp_probe_conflict(ll, in_packet);
 310                 }
 311
 312                 if (conflicted) {
 313                         log_ipv4ll(ll, "CONFLICT");
 314                         ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
 315                         if (!ll || ll->state == IPV4LL_STATE_STOPPED)
 316                                 goto out;
 317
 318                         ll->claimed_address = 0;
 319
 320                         /* Pick a new address */
 321                         r = ipv4ll_pick_address(ll, &ll->address);
 322                         if (r < 0)
 323                                 goto out;
 324                         ll->conflict++;
 325                         ll->defend_window = 0;
 326                         ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
 327
 328                         if (ll->conflict >= MAX_CONFLICTS) {
 329                                 log_ipv4ll(ll, "MAX_CONFLICTS");
 330                                 ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
 331                         } else
 332                                 ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
 333
 334                 }
 335         }
 336
 337         if (out_packet_ready) {
 338                 r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet);
 339                 if (r < 0) {
 340                         log_ipv4ll(ll, "failed to send arp packet out");
 341                         goto out;
 342                 }
 343         }
 344
 345         if (ll->next_wakeup_valid) {
 346                 ll->timer = sd_event_source_unref(ll->timer);
 347                 r = sd_event_add_time(ll->event, &ll->timer, CLOCK_MONOTONIC,
 348                                       ll->next_wakeup, 0, ipv4ll_timer, ll);
 349                 if (r < 0)
 350                         goto out;
 351
 352                 r = sd_event_source_set_priority(ll->timer, ll->event_priority);
 353                 if (r < 0)
 354                         goto out;
 355         }
 356
 357 out:
 358         if (r < 0 && ll)
 359                 ipv4ll_stop(ll, r);
 360 }
 361
 362 static int ipv4ll_receive_message(sd_event_source *s, int fd,
 363                                   uint32_t revents, void *userdata) {
 364         int r;
 365         struct ether_arp arp;
 366         sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
 367
 368         assert(ll);
 369
 370         r = read(fd, &arp, sizeof(struct ether_arp));
 371         if (r < (int) sizeof(struct ether_arp))
 372                 return 0;
 373
 374         r = arp_packet_verify_headers(&arp);
 375         if (r < 0)
 376                 return 0;
 377
 378         ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp);
 379
 380         return 0;
 381 }
 382
 383 int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
 384         assert_return(ll, -EINVAL);
 385         assert_return(interface_index > 0, -EINVAL);
 386         assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
 387                              IPV4LL_STATE_STOPPED), -EBUSY);
 388
 389         ll->index = interface_index;
 390
 391         return 0;
 392 }
 393
 394 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 395         bool need_restart = false;
 396
 397         assert_return(ll, -EINVAL);
 398         assert_return(addr, -EINVAL);
 399
 400         if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
 401                 return 0;
 402
 403         if (!IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED)) {
 404                 log_ipv4ll(ll, "Changing MAC address on running IPv4LL "
 405                            "client, restarting");
 406                 ll = ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 407                 need_restart = true;
 408         }
 409
 410         if (!ll)
 411                 return 0;
 412
 413         memcpy(&ll->mac_addr, addr, ETH_ALEN);
 414
 415         if (need_restart)
 416                 sd_ipv4ll_start(ll);
 417
 418         return 0;
 419 }
 420
 421 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 422         assert_return(ll, -EINVAL);
 423
 424         ll->event = sd_event_unref(ll->event);
 425
 426         return 0;
 427 }
 428
 429 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) {
 430         int r;
 431
 432         assert_return(ll, -EINVAL);
 433         assert_return(!ll->event, -EBUSY);
 434
 435         if (event)
 436                 ll->event = sd_event_ref(event);
 437         else {
 438                 r = sd_event_default(&ll->event);
 439                 if (r < 0) {
 440                         ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 441                         return r;
 442                 }
 443         }
 444
 445         ll->event_priority = priority;
 446
 447         return 0;
 448 }
 449
 450 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata) {
 451         assert_return(ll, -EINVAL);
 452
 453         ll->cb = cb;
 454         ll->userdata = userdata;
 455
 456         return 0;
 457 }
 458
 459 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){
 460         assert_return(ll, -EINVAL);
 461         assert_return(address, -EINVAL);
 462
 463         if (ll->claimed_address == 0) {
 464                 return -ENOENT;
 465         }
 466
 467         address->s_addr = ll->claimed_address;
 468         return 0;
 469 }
 470
 471 int sd_ipv4ll_set_address_seed (sd_ipv4ll *ll, uint8_t seed[8]) {
 472         unsigned int entropy;
 473         int r;
 474
 475         assert_return(ll, -EINVAL);
 476         assert_return(seed, -EINVAL);
 477
 478         entropy = *seed;
 479
 480         free(ll->random_data);
 481         free(ll->random_data_state);
 482
 483         ll->random_data = new0(struct random_data, 1);
 484         ll->random_data_state = new0(char, 128);
 485
 486         if (!ll->random_data || !ll->random_data_state) {
 487                 r = -ENOMEM;
 488                 goto error;
 489         }
 490
 491         r = initstate_r((unsigned int)entropy, ll->random_data_state, 128, ll->random_data);
 492         if (r < 0)
 493                 goto error;
 494
 495 error:
 496         if (r < 0){
 497                 free(ll->random_data);
 498                 free(ll->random_data_state);
 499                 ll->random_data = NULL;
 500                 ll->random_data_state = NULL;
 501         }
 502         return r;
 503 }
 504
 505 bool sd_ipv4ll_is_running(sd_ipv4ll *ll) {
 506         assert_return(ll, -EINVAL);
 507
 508         return !IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED);
 509 }
 510
 511 #define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 512
 513 int sd_ipv4ll_start (sd_ipv4ll *ll) {
 514         int r;
 515
 516         assert_return(ll, -EINVAL);
 517         assert_return(ll->event, -EINVAL);
 518         assert_return(ll->index > 0, -EINVAL);
 519         assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
 520                              IPV4LL_STATE_STOPPED), -EBUSY);
 521
 522         ll->state = IPV4LL_STATE_INIT;
 523
 524         r = arp_network_bind_raw_socket(ll->index, &ll->link);
 525
 526         if (r < 0)
 527                 goto out;
 528
 529         ll->fd = r;
 530         ll->conflict = 0;
 531         ll->defend_window = 0;
 532         ll->claimed_address = 0;
 533
 534         if (!ll->random_data) {
 535                 uint8_t seed[8];
 536
 537                 /* Fallback to mac */
 538                 siphash24(seed, &ll->mac_addr.ether_addr_octet,
 539                           ETH_ALEN, HASH_KEY.bytes);
 540
 541                 r = sd_ipv4ll_set_address_seed(ll, seed);
 542                 if (r < 0)
 543                         goto out;
 544         }
 545
 546         if (ll->address == 0) {
 547                 r = ipv4ll_pick_address(ll, &ll->address);
 548                 if (r < 0)
 549                         goto out;
 550         }
 551
 552         ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
 553
 554         r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
 555                             EPOLLIN, ipv4ll_receive_message, ll);
 556         if (r < 0)
 557                 goto out;
 558
 559         r = sd_event_source_set_priority(ll->receive_message, ll->event_priority);
 560         if (r < 0)
 561                 goto out;
 562
 563         r = sd_event_add_time(ll->event,
 564                               &ll->timer,
 565                               CLOCK_MONOTONIC,
 566                               now(CLOCK_MONOTONIC), 0,
 567                               ipv4ll_timer, ll);
 568
 569         if (r < 0)
 570                 goto out;
 571
 572         r = sd_event_source_set_priority(ll->timer, ll->event_priority);
 573
 574 out:
 575         if (r < 0)
 576                 ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 577
 578         return 0;
 579 }
 580
 581 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
 582         ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 583         if (ll)
 584                 ipv4ll_set_state(ll, IPV4LL_STATE_STOPPED, 1);
 585
 586         return 0;
 587 }
 588
 589 sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
 590         if (ll)
 591                 assert_se(REFCNT_INC(ll->n_ref) >= 2);
 592
 593         return ll;
 594 }
 595
 596 sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
 597         if (ll && REFCNT_DEC(ll->n_ref) <= 0) {
 598                 ll->receive_message =
 599                         sd_event_source_unref(ll->receive_message);
 600                 ll->fd = safe_close(ll->fd);
 601
 602                 ll->timer = sd_event_source_unref(ll->timer);
 603
 604                 sd_ipv4ll_detach_event(ll);
 605
 606                 free(ll->random_data);
 607                 free(ll->random_data_state);
 608                 free(ll);
 609
 610                 return NULL;
 611         }
 612
 613         return ll;
 614 }
 615
 616 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
 617 #define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_unrefp)
 618
 619 int sd_ipv4ll_new(sd_ipv4ll **ret) {
 620         _cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL;
 621
 622         assert_return(ret, -EINVAL);
 623
 624         ll = new0(sd_ipv4ll, 1);
 625         if (!ll)
 626                 return -ENOMEM;
 627
 628         ll->n_ref = REFCNT_INIT;
 629         ll->state = IPV4LL_STATE_INIT;
 630         ll->index = -1;
 631         ll->fd = -1;
 632
 633         *ret = ll;
 634         ll = NULL;
 635
 636         return 0;
 637 }