src/libsystemd-network/sd-icmp6-nd.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2014 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/ip6.h>
  22 #include <string.h>
  23 #include <stdbool.h>
  24 #include <netinet/in.h>
  25 #include <sys/ioctl.h>
  26
  27 #include "socket-util.h"
  28 #include "refcnt.h"
  29 #include "async.h"
  30
  31 #include "dhcp6-internal.h"
  32 #include "sd-icmp6-nd.h"
  33
  34 #define ICMP6_ROUTER_SOLICITATION_INTERVAL      4 * USEC_PER_SEC
  35 #define ICMP6_MAX_ROUTER_SOLICITATIONS          3
  36
  37 enum icmp6_nd_state {
  38         ICMP6_NEIGHBOR_DISCOVERY_IDLE           = 0,
  39         ICMP6_ROUTER_SOLICITATION_SENT          = 10,
  40         ICMP6_ROUTER_ADVERTISMENT_LISTEN        = 11,
  41 };
  42
  43 #define IP6_MIN_MTU (unsigned)1280
  44 #define ICMP6_ND_RECV_SIZE (IP6_MIN_MTU - sizeof(struct ip6_hdr))
  45 #define ICMP6_OPT_LEN_UNITS 8
  46
  47 typedef struct ICMP6Prefix ICMP6Prefix;
  48
  49 struct ICMP6Prefix {
  50         RefCount n_ref;
  51
  52         LIST_FIELDS(ICMP6Prefix, prefixes);
  53
  54         uint8_t len;
  55         sd_event_source *timeout_valid;
  56         struct in6_addr addr;
  57 };
  58
  59 struct sd_icmp6_nd {
  60         RefCount n_ref;
  61
  62         enum icmp6_nd_state state;
  63         sd_event *event;
  64         int event_priority;
  65         int index;
  66         struct ether_addr mac_addr;
  67         uint32_t mtu;
  68         LIST_HEAD(ICMP6Prefix, prefixes);
  69         int fd;
  70         sd_event_source *recv;
  71         sd_event_source *timeout;
  72         int nd_sent;
  73         sd_icmp6_nd_callback_t callback;
  74         void *userdata;
  75 };
  76
  77 #define log_icmp6_nd(p, fmt, ...) log_internal(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "ICMPv6 CLIENT: " fmt, ##__VA_ARGS__)
  78
  79 static ICMP6Prefix *icmp6_prefix_unref(ICMP6Prefix *prefix) {
  80         if (prefix && REFCNT_DEC(prefix->n_ref) <= 0) {
  81                 prefix->timeout_valid =
  82                         sd_event_source_unref(prefix->timeout_valid);
  83
  84                 free(prefix);
  85         }
  86
  87         return NULL;
  88 }
  89
  90 static int icmp6_prefix_new(ICMP6Prefix **ret) {
  91         _cleanup_free_ ICMP6Prefix *prefix = NULL;
  92
  93         assert(ret);
  94
  95         prefix = new0(ICMP6Prefix, 1);
  96         if (!prefix)
  97                 return -ENOMEM;
  98
  99         prefix->n_ref = REFCNT_INIT;
 100         LIST_INIT(prefixes, prefix);
 101
 102         *ret = prefix;
 103         prefix = NULL;
 104
 105         return 0;
 106 }
 107
 108 static void icmp6_nd_notify(sd_icmp6_nd *nd, int event)
 109 {
 110         if (nd->callback)
 111                 nd->callback(nd, event, nd->userdata);
 112 }
 113
 114 int sd_icmp6_nd_set_callback(sd_icmp6_nd *nd, sd_icmp6_nd_callback_t callback,
 115                              void *userdata) {
 116         assert(nd);
 117
 118         nd->callback = callback;
 119         nd->userdata = userdata;
 120
 121         return 0;
 122 }
 123
 124 int sd_icmp6_nd_set_index(sd_icmp6_nd *nd, int interface_index) {
 125         assert(nd);
 126         assert(interface_index >= -1);
 127
 128         nd->index = interface_index;
 129
 130         return 0;
 131 }
 132
 133 int sd_icmp6_nd_set_mac(sd_icmp6_nd *nd, const struct ether_addr *mac_addr) {
 134         assert(nd);
 135
 136         if (mac_addr)
 137                 memcpy(&nd->mac_addr, mac_addr, sizeof(nd->mac_addr));
 138         else
 139                 zero(nd->mac_addr);
 140
 141         return 0;
 142
 143 }
 144
 145 int sd_icmp6_nd_attach_event(sd_icmp6_nd *nd, sd_event *event, int priority) {
 146         int r;
 147
 148         assert_return(nd, -EINVAL);
 149         assert_return(!nd->event, -EBUSY);
 150
 151         if (event)
 152                 nd->event = sd_event_ref(event);
 153         else {
 154                 r = sd_event_default(&nd->event);
 155                 if (r < 0)
 156                         return 0;
 157         }
 158
 159         nd->event_priority = priority;
 160
 161         return 0;
 162 }
 163
 164 int sd_icmp6_nd_detach_event(sd_icmp6_nd *nd) {
 165         assert_return(nd, -EINVAL);
 166
 167         nd->event = sd_event_unref(nd->event);
 168
 169         return 0;
 170 }
 171
 172 sd_event *sd_icmp6_nd_get_event(sd_icmp6_nd *nd) {
 173         assert(nd);
 174
 175         return nd->event;
 176 }
 177
 178 sd_icmp6_nd *sd_icmp6_nd_ref(sd_icmp6_nd *nd) {
 179         assert (nd);
 180
 181         assert_se(REFCNT_INC(nd->n_ref) >= 2);
 182
 183         return nd;
 184 }
 185
 186 static int icmp6_nd_init(sd_icmp6_nd *nd) {
 187         assert(nd);
 188
 189         nd->recv = sd_event_source_unref(nd->recv);
 190         nd->fd = asynchronous_close(nd->fd);
 191         nd->timeout = sd_event_source_unref(nd->timeout);
 192
 193         return 0;
 194 }
 195
 196 sd_icmp6_nd *sd_icmp6_nd_unref(sd_icmp6_nd *nd) {
 197         if (nd && REFCNT_DEC(nd->n_ref) == 0) {
 198                 ICMP6Prefix *prefix, *p;
 199
 200                 icmp6_nd_init(nd);
 201                 sd_icmp6_nd_detach_event(nd);
 202
 203                 LIST_FOREACH_SAFE(prefixes, prefix, p, nd->prefixes) {
 204                         LIST_REMOVE(prefixes, nd->prefixes, prefix);
 205
 206                         prefix = icmp6_prefix_unref(prefix);
 207                 }
 208
 209                 free(nd);
 210         }
 211
 212         return NULL;
 213 }
 214
 215 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_icmp6_nd*, sd_icmp6_nd_unref);
 216 #define _cleanup_sd_icmp6_nd_free_ _cleanup_(sd_icmp6_nd_unrefp)
 217
 218 int sd_icmp6_nd_new(sd_icmp6_nd **ret) {
 219         _cleanup_sd_icmp6_nd_free_ sd_icmp6_nd *nd = NULL;
 220
 221         assert(ret);
 222
 223         nd = new0(sd_icmp6_nd, 1);
 224         if (!nd)
 225                 return -ENOMEM;
 226
 227         nd->n_ref = REFCNT_INIT;
 228
 229         nd->index = -1;
 230         nd->fd = -1;
 231
 232         LIST_HEAD_INIT(nd->prefixes);
 233
 234         *ret = nd;
 235         nd = NULL;
 236
 237         return 0;
 238 }
 239
 240 int sd_icmp6_ra_get_mtu(sd_icmp6_nd *nd, uint32_t *mtu) {
 241         assert_return(nd, -EINVAL);
 242         assert_return(mtu, -EINVAL);
 243
 244         if (nd->mtu == 0)
 245                 return -ENOMSG;
 246
 247         *mtu = nd->mtu;
 248
 249         return 0;
 250 }
 251
 252 static int icmp6_ra_parse(sd_icmp6_nd *nd, struct nd_router_advert *ra,
 253                           ssize_t len) {
 254         void *opt;
 255         struct nd_opt_hdr *opt_hdr;
 256
 257         assert_return(nd, -EINVAL);
 258         assert_return(ra, -EINVAL);
 259
 260         len -= sizeof(*ra);
 261         if (len < ICMP6_OPT_LEN_UNITS) {
 262                 log_icmp6_nd(nd, "Router Advertisement below minimum length");
 263
 264                 return -ENOMSG;
 265         }
 266
 267         opt = ra + 1;
 268         opt_hdr = opt;
 269
 270         while (len != 0 && len >= opt_hdr->nd_opt_len * ICMP6_OPT_LEN_UNITS) {
 271                 struct nd_opt_mtu *opt_mtu;
 272                 uint32_t mtu;
 273
 274                 if (opt_hdr->nd_opt_len == 0)
 275                         return -ENOMSG;
 276
 277                 switch (opt_hdr->nd_opt_type) {
 278                 case ND_OPT_MTU:
 279                         opt_mtu = opt;
 280
 281                         mtu = be32toh(opt_mtu->nd_opt_mtu_mtu);
 282
 283                         if (mtu != nd->mtu) {
 284                                 nd->mtu = MAX(mtu, IP6_MIN_MTU);
 285
 286                                 log_icmp6_nd(nd, "Router Advertisement link MTU %d using %d",
 287                                              mtu, nd->mtu);
 288                         }
 289
 290                         break;
 291
 292                 }
 293
 294                 len -= opt_hdr->nd_opt_len * ICMP6_OPT_LEN_UNITS;
 295                 opt = (void *)((char *)opt +
 296                         opt_hdr->nd_opt_len * ICMP6_OPT_LEN_UNITS);
 297                 opt_hdr = opt;
 298         }
 299
 300         if (len > 0)
 301                 log_icmp6_nd(nd, "Router Advertisement contains %zd bytes of trailing garbage", len);
 302
 303         return 0;
 304 }
 305
 306 static int icmp6_router_advertisment_recv(sd_event_source *s, int fd,
 307                                           uint32_t revents, void *userdata)
 308 {
 309         sd_icmp6_nd *nd = userdata;
 310         int r, buflen = 0;
 311         ssize_t len;
 312         _cleanup_free_ struct nd_router_advert *ra = NULL;
 313         int event = ICMP6_EVENT_ROUTER_ADVERTISMENT_NONE;
 314
 315         assert(s);
 316         assert(nd);
 317         assert(nd->event);
 318
 319         r = ioctl(fd, FIONREAD, &buflen);
 320         if (r < 0 || buflen <= 0)
 321                 buflen = ICMP6_ND_RECV_SIZE;
 322
 323         ra = malloc(buflen);
 324         if (!ra)
 325                 return -ENOMEM;
 326
 327         len = read(fd, ra, buflen);
 328         if (len < 0) {
 329                 log_icmp6_nd(nd, "Could not receive message from UDP socket: %m");
 330                 return 0;
 331         }
 332
 333         if (ra->nd_ra_type != ND_ROUTER_ADVERT)
 334                 return 0;
 335
 336         if (ra->nd_ra_code != 0)
 337                 return 0;
 338
 339         nd->timeout = sd_event_source_unref(nd->timeout);
 340
 341         nd->state = ICMP6_ROUTER_ADVERTISMENT_LISTEN;
 342
 343         if (ra->nd_ra_flags_reserved & ND_RA_FLAG_OTHER )
 344                 event = ICMP6_EVENT_ROUTER_ADVERTISMENT_OTHER;
 345
 346         if (ra->nd_ra_flags_reserved & ND_RA_FLAG_MANAGED)
 347                 event = ICMP6_EVENT_ROUTER_ADVERTISMENT_MANAGED;
 348
 349         log_icmp6_nd(nd, "Received Router Advertisement flags %s/%s",
 350                      ra->nd_ra_flags_reserved & ND_RA_FLAG_MANAGED? "MANAGED": "none",
 351                      ra->nd_ra_flags_reserved & ND_RA_FLAG_OTHER? "OTHER": "none");
 352
 353         if (event != ICMP6_EVENT_ROUTER_ADVERTISMENT_NONE) {
 354                 r = icmp6_ra_parse(nd, ra, len);
 355                 if (r < 0) {
 356                         log_icmp6_nd(nd, "Could not parse Router Advertisement: %s",
 357                                      strerror(-r));
 358                         return 0;
 359                 }
 360         }
 361
 362         icmp6_nd_notify(nd, event);
 363
 364         return 0;
 365 }
 366
 367 static int icmp6_router_solicitation_timeout(sd_event_source *s, uint64_t usec,
 368                                              void *userdata)
 369 {
 370         sd_icmp6_nd *nd = userdata;
 371         uint64_t time_now, next_timeout;
 372         struct ether_addr unset = { };
 373         struct ether_addr *addr = NULL;
 374         int r;
 375
 376         assert(s);
 377         assert(nd);
 378         assert(nd->event);
 379
 380         nd->timeout = sd_event_source_unref(nd->timeout);
 381
 382         if (nd->nd_sent >= ICMP6_MAX_ROUTER_SOLICITATIONS) {
 383                 icmp6_nd_notify(nd, ICMP6_EVENT_ROUTER_ADVERTISMENT_TIMEOUT);
 384                 nd->state = ICMP6_ROUTER_ADVERTISMENT_LISTEN;
 385         } else {
 386                 if (memcmp(&nd->mac_addr, &unset, sizeof(struct ether_addr)))
 387                         addr = &nd->mac_addr;
 388
 389                 r = dhcp_network_icmp6_send_router_solicitation(nd->fd, addr);
 390                 if (r < 0)
 391                         log_icmp6_nd(nd, "Error sending Router Solicitation");
 392                 else {
 393                         nd->state = ICMP6_ROUTER_SOLICITATION_SENT;
 394                         log_icmp6_nd(nd, "Sent Router Solicitation");
 395                 }
 396
 397                 nd->nd_sent++;
 398
 399                 r = sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now);
 400                 if (r < 0) {
 401                         icmp6_nd_notify(nd, r);
 402                         return 0;
 403                 }
 404
 405                 next_timeout = time_now + ICMP6_ROUTER_SOLICITATION_INTERVAL;
 406
 407                 r = sd_event_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
 408                                       next_timeout, 0,
 409                                       icmp6_router_solicitation_timeout, nd);
 410                 if (r < 0) {
 411                         icmp6_nd_notify(nd, r);
 412                         return 0;
 413                 }
 414
 415                 r = sd_event_source_set_priority(nd->timeout,
 416                                                  nd->event_priority);
 417                 if (r < 0) {
 418                         icmp6_nd_notify(nd, r);
 419                         return 0;
 420                 }
 421
 422                 r = sd_event_source_set_description(nd->timeout, "icmp6-timeout");
 423                 if (r < 0) {
 424                         icmp6_nd_notify(nd, r);
 425                         return 0;
 426                 }
 427         }
 428
 429         return 0;
 430 }
 431
 432 int sd_icmp6_nd_stop(sd_icmp6_nd *nd) {
 433         assert_return(nd, -EINVAL);
 434         assert_return(nd->event, -EINVAL);
 435
 436         log_icmp6_nd(client, "Stop ICMPv6");
 437
 438         icmp6_nd_init(nd);
 439
 440         nd->state = ICMP6_NEIGHBOR_DISCOVERY_IDLE;
 441
 442         return 0;
 443 }
 444
 445 int sd_icmp6_router_solicitation_start(sd_icmp6_nd *nd) {
 446         int r;
 447
 448         assert(nd);
 449         assert(nd->event);
 450
 451         if (nd->state != ICMP6_NEIGHBOR_DISCOVERY_IDLE)
 452                 return -EINVAL;
 453
 454         if (nd->index < 1)
 455                 return -EINVAL;
 456
 457         r = dhcp_network_icmp6_bind_router_solicitation(nd->index);
 458         if (r < 0)
 459                 return r;
 460
 461         nd->fd = r;
 462
 463         r = sd_event_add_io(nd->event, &nd->recv, nd->fd, EPOLLIN,
 464                             icmp6_router_advertisment_recv, nd);
 465         if (r < 0)
 466                 goto error;
 467
 468         r = sd_event_source_set_priority(nd->recv, nd->event_priority);
 469         if (r < 0)
 470                 goto error;
 471
 472         r = sd_event_source_set_description(nd->recv, "icmp6-receive-message");
 473         if (r < 0)
 474                 goto error;
 475
 476         r = sd_event_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
 477                               0, 0, icmp6_router_solicitation_timeout, nd);
 478         if (r < 0)
 479                 goto error;
 480
 481         r = sd_event_source_set_priority(nd->timeout, nd->event_priority);
 482         if (r < 0)
 483                 goto error;
 484
 485         r = sd_event_source_set_description(nd->timeout, "icmp6-timeout");
 486 error:
 487         if (r < 0)
 488                 icmp6_nd_init(nd);
 489         else
 490                 log_icmp6_nd(client, "Start Router Solicitation");
 491
 492         return r;
 493 }