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
  30 #include "ipv4ll-internal.h"
  31 #include "sd-ipv4ll.h"
  32
  33 /* Constants from the RFC */
  34 #define PROBE_WAIT 1
  35 #define PROBE_NUM 3
  36 #define PROBE_MIN 1
  37 #define PROBE_MAX 2
  38 #define ANNOUNCE_WAIT 2
  39 #define ANNOUNCE_NUM 2
  40 #define ANNOUNCE_INTERVAL 2
  41 #define MAX_CONFLICTS 10
  42 #define RATE_LIMIT_INTERVAL 60
  43 #define DEFEND_INTERVAL 10
  44
  45 #define IPV4LL_NETWORK 0xA9FE0000L
  46 #define IPV4LL_NETMASK 0xFFFF0000L
  47
  48 typedef enum IPv4LLTrigger{
  49         IPV4LL_TRIGGER_NULL,
  50         IPV4LL_TRIGGER_PACKET,
  51         IPV4LL_TRIGGER_TIMEOUT,
  52         _IPV4LL_TRIGGER_MAX,
  53         _IPV4LL_TRIGGER_INVALID = -1
  54 } IPv4LLTrigger;
  55
  56 typedef enum IPv4LLState {
  57         IPV4LL_STATE_INIT,
  58         IPV4LL_STATE_WAITING_PROBE,
  59         IPV4LL_STATE_PROBING,
  60         IPV4LL_STATE_WAITING_ANNOUNCE,
  61         IPV4LL_STATE_ANNOUNCING,
  62         IPV4LL_STATE_RUNNING,
  63         _IPV4LL_STATE_MAX,
  64         _IPV4LL_STATE_INVALID = -1
  65 } IPv4LLState;
  66
  67 struct sd_ipv4ll {
  68         IPv4LLState state;
  69         int index;
  70         int fd;
  71         union sockaddr_union link;
  72         int iteration;
  73         int conflict;
  74         sd_event_source *receive_message;
  75         sd_event_source *timer;
  76         usec_t next_wakeup;
  77         usec_t defend_window;
  78         int next_wakeup_valid;
  79         be32_t address;
  80         struct random_data *random_data;
  81         char *random_data_state;
  82         /* External */
  83         be32_t claimed_address;
  84         struct ether_addr mac_addr;
  85         sd_event *event;
  86         int event_priority;
  87         sd_ipv4ll_cb_t cb;
  88         void* userdata;
  89 };
  90
  91 static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data);
  92
  93 static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) {
  94
  95         assert(ll);
  96         assert(st < _IPV4LL_STATE_MAX);
  97
  98         if (st == ll->state && !reset_counter) {
  99                 ll->iteration++;
 100         } else {
 101                 ll->state = st;
 102                 ll->iteration = 0;
 103         }
 104 }
 105
 106 static int ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 107         assert(ll);
 108
 109         if (ll->cb)
 110                 ll->cb(ll, event, ll->userdata);
 111
 112         return 0;
 113 }
 114
 115 static int ipv4ll_stop(sd_ipv4ll *ll, int event) {
 116         assert(ll);
 117
 118         ll->receive_message = sd_event_source_unref(ll->receive_message);
 119         ll->fd = safe_close(ll->fd);
 120
 121         ll->timer = sd_event_source_unref(ll->timer);
 122
 123         ipv4ll_client_notify(ll, event);
 124
 125         ll->claimed_address = 0;
 126
 127         ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
 128
 129         log_ipv4ll(ll, "STOPPED");
 130
 131         return 0;
 132 }
 133
 134 static int ipv4ll_pick_address(sd_ipv4ll *ll, be32_t *address) {
 135         be32_t addr;
 136         int r;
 137         int32_t random;
 138
 139         assert(ll);
 140         assert(address);
 141         assert(ll->random_data);
 142
 143         do {
 144                 r = random_r(ll->random_data, &random);
 145                 if (r < 0)
 146                         return r;
 147                 addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
 148         } while (addr == ll->address ||
 149                 (ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
 150                 (ntohl(addr) & 0x0000FF00) == 0x0000 ||
 151                 (ntohl(addr) & 0x0000FF00) == 0xFF00);
 152
 153         *address = addr;
 154         return 0;
 155 }
 156
 157 static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) {
 158         sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
 159
 160         assert(ll);
 161
 162         ll->next_wakeup_valid = 0;
 163         ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL);
 164
 165         return 0;
 166 }
 167
 168 static void ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
 169         usec_t next_timeout = 0;
 170         usec_t time_now = 0;
 171
 172         assert(sec >= 0);
 173         assert(random_sec >= 0);
 174         assert(ll);
 175
 176         next_timeout = sec * USEC_PER_SEC;
 177
 178         if (random_sec)
 179                 next_timeout += random_u32() % (random_sec * USEC_PER_SEC);
 180
 181         if (sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now) < 0)
 182                 time_now = now(CLOCK_MONOTONIC);
 183
 184         ll->next_wakeup = time_now + next_timeout;
 185         ll->next_wakeup_valid = 1;
 186 }
 187
 188 static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
 189         assert(ll);
 190         assert(arp);
 191
 192         if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 &&
 193             memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0)
 194                 return true;
 195
 196         return false;
 197 }
 198
 199 static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
 200         assert(ll);
 201         assert(arp);
 202
 203         if (ipv4ll_arp_conflict(ll, arp))
 204                 return true;
 205
 206         if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 &&
 207             memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN))
 208                 return true;
 209
 210         return false;
 211 }
 212
 213 static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {
 214         struct ether_arp out_packet;
 215         int out_packet_ready = 0;
 216         int r = 0;
 217
 218         assert(ll);
 219         assert(trigger < _IPV4LL_TRIGGER_MAX);
 220
 221         if (ll->state == IPV4LL_STATE_INIT) {
 222
 223                 log_ipv4ll(ll, "PROBE");
 224                 ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
 225                 ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
 226
 227         } else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
 228                 (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) {
 229
 230                 /* Send a probe */
 231                 arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
 232                 out_packet_ready = 1;
 233                 ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0);
 234
 235                 ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
 236
 237         } else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) {
 238
 239                 /* Send the last probe */
 240                 arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
 241                 out_packet_ready = 1;
 242                 ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1);
 243
 244                 ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
 245
 246         } else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
 247                 (ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) {
 248
 249                 /* Send announcement packet */
 250                 arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
 251                 out_packet_ready = 1;
 252                 ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0);
 253
 254                 ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
 255
 256                 if (ll->iteration == 0) {
 257                         log_ipv4ll(ll, "ANNOUNCE");
 258                         ll->claimed_address = ll->address;
 259                         r = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
 260                         ll->conflict = 0;
 261                 }
 262
 263         } else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT &&
 264                     ll->iteration >= ANNOUNCE_NUM-1)) {
 265
 266                 ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0);
 267                 ll->next_wakeup_valid = 0;
 268
 269         } else if (trigger == IPV4LL_TRIGGER_PACKET) {
 270
 271                 int conflicted = 0;
 272                 usec_t time_now;
 273                 struct ether_arp* in_packet = (struct ether_arp*)trigger_data;
 274
 275                 assert(in_packet);
 276
 277                 if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) {
 278
 279                         if (ipv4ll_arp_conflict(ll, in_packet)) {
 280
 281                                 r = sd_event_now(ll->event, CLOCK_MONOTONIC, &time_now);
 282                                 if (r < 0)
 283                                         goto out;
 284
 285                                 /* Defend address */
 286                                 if (time_now > ll->defend_window) {
 287                                         ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC;
 288                                         arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
 289                                         out_packet_ready = 1;
 290                                 } else
 291                                         conflicted = 1;
 292                         }
 293
 294                 } else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE,
 295                                              IPV4LL_STATE_PROBING,
 296                                              IPV4LL_STATE_WAITING_ANNOUNCE)) {
 297
 298                         conflicted = ipv4ll_arp_probe_conflict(ll, in_packet);
 299                 }
 300
 301                 if (conflicted) {
 302                         log_ipv4ll(ll, "CONFLICT");
 303                         r = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
 304                         ll->claimed_address = 0;
 305
 306                         /* Pick a new address */
 307                         r = ipv4ll_pick_address(ll, &ll->address);
 308                         if (r < 0)
 309                                 goto out;
 310                         ll->conflict++;
 311                         ll->defend_window = 0;
 312                         ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
 313
 314                         if (ll->conflict >= MAX_CONFLICTS) {
 315                                 log_ipv4ll(ll, "MAX_CONFLICTS");
 316                                 ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
 317                         } else
 318                                 ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
 319
 320                 }
 321         }
 322
 323         if (out_packet_ready) {
 324                 r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet);
 325                 if (r < 0) {
 326                         log_ipv4ll(ll, "failed to send arp packet out");
 327                         goto out;
 328                 }
 329         }
 330
 331         if (ll->next_wakeup_valid) {
 332                 ll->timer = sd_event_source_unref(ll->timer);
 333                 r = sd_event_add_time(ll->event, &ll->timer, CLOCK_MONOTONIC,
 334                                       ll->next_wakeup, 0, ipv4ll_timer, ll);
 335                 if (r < 0)
 336                         goto out;
 337
 338                 r = sd_event_source_set_priority(ll->timer, ll->event_priority);
 339                 if (r < 0)
 340                         goto out;
 341         }
 342
 343 out:
 344         if (r < 0)
 345                 ipv4ll_stop(ll, r);
 346 }
 347
 348 static int ipv4ll_receive_message(sd_event_source *s, int fd,
 349                                   uint32_t revents, void *userdata) {
 350         int r;
 351         struct ether_arp arp;
 352         sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
 353
 354         assert(ll);
 355
 356         r = read(fd, &arp, sizeof(struct ether_arp));
 357         if (r < (int) sizeof(struct ether_arp))
 358                 return 0;
 359
 360         r = arp_packet_verify_headers(&arp);
 361         if (r < 0)
 362                 return 0;
 363
 364         ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp);
 365
 366         return 0;
 367 }
 368
 369 int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
 370         assert_return(ll, -EINVAL);
 371         assert_return(interface_index >= -1, -EINVAL);
 372         assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
 373
 374         ll->index = interface_index;
 375
 376         return 0;
 377 }
 378
 379 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 380         bool need_restart = false;
 381
 382         assert_return(ll, -EINVAL);
 383         assert_return(addr, -EINVAL);
 384
 385         if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
 386                 return 0;
 387
 388         if (ll->state != IPV4LL_STATE_INIT) {
 389                 log_ipv4ll(ll, "Changing MAC address on running IPv4LL "
 390                            "client, restarting");
 391                 sd_ipv4ll_stop(ll);
 392                 need_restart = true;
 393         }
 394
 395         memcpy(&ll->mac_addr, addr, ETH_ALEN);
 396
 397         if (need_restart)
 398                 sd_ipv4ll_start(ll);
 399
 400         return 0;
 401 }
 402
 403 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 404         assert_return(ll, -EINVAL);
 405
 406         ll->event = sd_event_unref(ll->event);
 407
 408         return 0;
 409 }
 410
 411 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) {
 412         int r;
 413
 414         assert_return(ll, -EINVAL);
 415         assert_return(!ll->event, -EBUSY);
 416
 417         if (event)
 418                 ll->event = sd_event_ref(event);
 419         else {
 420                 r = sd_event_default(&ll->event);
 421                 if (r < 0) {
 422                         ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 423                         return r;
 424                 }
 425         }
 426
 427         ll->event_priority = priority;
 428
 429         return 0;
 430 }
 431
 432 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata) {
 433         assert_return(ll, -EINVAL);
 434
 435         ll->cb = cb;
 436         ll->userdata = userdata;
 437
 438         return 0;
 439 }
 440
 441 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){
 442         assert_return(ll, -EINVAL);
 443         assert_return(address, -EINVAL);
 444
 445         if (ll->claimed_address == 0) {
 446                 return -ENOENT;
 447         }
 448
 449         address->s_addr = ll->claimed_address;
 450         return 0;
 451 }
 452
 453 int sd_ipv4ll_set_address_seed (sd_ipv4ll *ll, uint8_t seed[8]) {
 454         unsigned int entropy = *seed;
 455         int r;
 456
 457         assert_return(ll, -EINVAL);
 458
 459         free(ll->random_data);
 460         free(ll->random_data_state);
 461
 462         ll->random_data = new0(struct random_data, 1);
 463         ll->random_data_state = new0(char, 128);
 464
 465         if (!ll->random_data || !ll->random_data_state) {
 466                 r = -ENOMEM;
 467                 goto error;
 468         }
 469
 470         r = initstate_r((unsigned int)entropy, ll->random_data_state, 128, ll->random_data);
 471         if (r < 0)
 472                 goto error;
 473
 474 error:
 475         if (r < 0){
 476                 free(ll->random_data);
 477                 free(ll->random_data_state);
 478                 ll->random_data = NULL;
 479                 ll->random_data_state = NULL;
 480         }
 481         return r;
 482 }
 483
 484 #define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 485
 486 int sd_ipv4ll_start (sd_ipv4ll *ll) {
 487         int r;
 488
 489         assert_return(ll, -EINVAL);
 490         assert_return(ll->event, -EINVAL);
 491         assert_return(ll->index > 0, -EINVAL);
 492         assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
 493
 494         r = arp_network_bind_raw_socket(ll->index, &ll->link);
 495
 496         if (r < 0)
 497                 goto out;
 498
 499         ll->fd = r;
 500         ll->conflict = 0;
 501         ll->defend_window = 0;
 502         ll->claimed_address = 0;
 503
 504         if (!ll->random_data) {
 505                 uint8_t seed[8];
 506
 507                 /* Fallback to mac */
 508                 siphash24(seed, &ll->mac_addr.ether_addr_octet,
 509                           ETH_ALEN, HASH_KEY.bytes);
 510
 511                 r = sd_ipv4ll_set_address_seed(ll, seed);
 512                 if (r < 0)
 513                         goto out;
 514         }
 515
 516         if (ll->address == 0) {
 517                 r = ipv4ll_pick_address(ll, &ll->address);
 518                 if (r < 0)
 519                         goto out;
 520         }
 521
 522         ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
 523
 524         r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
 525                             EPOLLIN, ipv4ll_receive_message, ll);
 526         if (r < 0)
 527                 goto out;
 528
 529         r = sd_event_source_set_priority(ll->receive_message, ll->event_priority);
 530         if (r < 0)
 531                 goto out;
 532
 533         r = sd_event_add_time(ll->event,
 534                               &ll->timer,
 535                               CLOCK_MONOTONIC,
 536                               now(CLOCK_MONOTONIC), 0,
 537                               ipv4ll_timer, ll);
 538
 539         if (r < 0)
 540                 goto out;
 541
 542         r = sd_event_source_set_priority(ll->timer, ll->event_priority);
 543
 544 out:
 545         if (r < 0)
 546                 ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 547
 548         return 0;
 549 }
 550
 551 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
 552         return ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
 553 }
 554
 555 void sd_ipv4ll_free (sd_ipv4ll *ll) {
 556         if (!ll)
 557                 return;
 558
 559         sd_ipv4ll_stop(ll);
 560         sd_ipv4ll_detach_event(ll);
 561
 562         free(ll->random_data);
 563         free(ll->random_data_state);
 564         free(ll);
 565 }
 566
 567 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_free);
 568 #define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_freep)
 569
 570 int sd_ipv4ll_new(sd_ipv4ll **ret) {
 571         _cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL;
 572
 573         assert_return(ret, -EINVAL);
 574
 575         ll = new0(sd_ipv4ll, 1);
 576         if (!ll)
 577                 return -ENOMEM;
 578
 579         ll->state = IPV4LL_STATE_INIT;
 580         ll->index = -1;
 581         ll->fd = -1;
 582
 583         *ret = ll;
 584         ll = NULL;
 585
 586         return 0;
 587 }