src/libsystemd-network/sd-ndisc.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/in.h>
  22
  23 #include "sd-ndisc.h"
  24
  25 #include "alloc-util.h"
  26 #include "fd-util.h"
  27 #include "icmp6-util.h"
  28 #include "in-addr-util.h"
  29 #include "ndisc-internal.h"
  30 #include "ndisc-router.h"
  31 #include "socket-util.h"
  32 #include "string-util.h"
  33 #include "util.h"
  34
  35 #define NDISC_ROUTER_SOLICITATION_INTERVAL (4U * USEC_PER_SEC)
  36 #define NDISC_MAX_ROUTER_SOLICITATIONS 3U
  37
  38 static void ndisc_callback(sd_ndisc *ndisc, sd_ndisc_event event, sd_ndisc_router *rt) {
  39         assert(ndisc);
  40
  41         log_ndisc("Invoking callback for '%c'.", event);
  42
  43         if (!ndisc->callback)
  44                 return;
  45
  46         ndisc->callback(ndisc, event, rt, ndisc->userdata);
  47 }
  48
  49 _public_ int sd_ndisc_set_callback(
  50                 sd_ndisc *nd,
  51                 sd_ndisc_callback_t callback,
  52                 void *userdata) {
  53
  54         assert_return(nd, -EINVAL);
  55
  56         nd->callback = callback;
  57         nd->userdata = userdata;
  58
  59         return 0;
  60 }
  61
  62 _public_ int sd_ndisc_set_ifindex(sd_ndisc *nd, int ifindex) {
  63         assert_return(nd, -EINVAL);
  64         assert_return(ifindex > 0, -EINVAL);
  65         assert_return(nd->fd < 0, -EBUSY);
  66
  67         nd->ifindex = ifindex;
  68         return 0;
  69 }
  70
  71 _public_ int sd_ndisc_set_mac(sd_ndisc *nd, const struct ether_addr *mac_addr) {
  72         assert_return(nd, -EINVAL);
  73
  74         if (mac_addr)
  75                 nd->mac_addr = *mac_addr;
  76         else
  77                 zero(nd->mac_addr);
  78
  79         return 0;
  80 }
  81
  82 _public_ int sd_ndisc_attach_event(sd_ndisc *nd, sd_event *event, int64_t priority) {
  83         int r;
  84
  85         assert_return(nd, -EINVAL);
  86         assert_return(nd->fd < 0, -EBUSY);
  87         assert_return(!nd->event, -EBUSY);
  88
  89         if (event)
  90                 nd->event = sd_event_ref(event);
  91         else {
  92                 r = sd_event_default(&nd->event);
  93                 if (r < 0)
  94                         return 0;
  95         }
  96
  97         nd->event_priority = priority;
  98
  99         return 0;
 100 }
 101
 102 _public_ int sd_ndisc_detach_event(sd_ndisc *nd) {
 103
 104         assert_return(nd, -EINVAL);
 105         assert_return(nd->fd < 0, -EBUSY);
 106
 107         nd->event = sd_event_unref(nd->event);
 108         return 0;
 109 }
 110
 111 _public_ sd_event *sd_ndisc_get_event(sd_ndisc *nd) {
 112         assert_return(nd, NULL);
 113
 114         return nd->event;
 115 }
 116
 117 _public_ sd_ndisc *sd_ndisc_ref(sd_ndisc *nd) {
 118
 119         if (!nd)
 120                 return NULL;
 121
 122         assert(nd->n_ref > 0);
 123         nd->n_ref++;
 124
 125         return nd;
 126 }
 127
 128 static int ndisc_reset(sd_ndisc *nd) {
 129         assert(nd);
 130
 131         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 132         nd->recv_event_source = sd_event_source_unref(nd->recv_event_source);
 133         nd->fd = safe_close(nd->fd);
 134
 135         return 0;
 136 }
 137
 138 _public_ sd_ndisc *sd_ndisc_unref(sd_ndisc *nd) {
 139
 140         if (!nd)
 141                 return NULL;
 142
 143         assert(nd->n_ref > 0);
 144         nd->n_ref--;
 145
 146         if (nd->n_ref > 0)
 147                 return NULL;
 148
 149         ndisc_reset(nd);
 150         sd_ndisc_detach_event(nd);
 151         free(nd);
 152
 153         return NULL;
 154 }
 155
 156 _public_ int sd_ndisc_new(sd_ndisc **ret) {
 157         _cleanup_(sd_ndisc_unrefp) sd_ndisc *nd = NULL;
 158
 159         assert_return(ret, -EINVAL);
 160
 161         nd = new0(sd_ndisc, 1);
 162         if (!nd)
 163                 return -ENOMEM;
 164
 165         nd->n_ref = 1;
 166         nd->fd = -1;
 167
 168         *ret = nd;
 169         nd = NULL;
 170
 171         return 0;
 172 }
 173
 174 _public_ int sd_ndisc_get_mtu(sd_ndisc *nd, uint32_t *mtu) {
 175         assert_return(nd, -EINVAL);
 176         assert_return(mtu, -EINVAL);
 177
 178         if (nd->mtu == 0)
 179                 return -ENODATA;
 180
 181         *mtu = nd->mtu;
 182         return 0;
 183 }
 184
 185 _public_ int sd_ndisc_get_hop_limit(sd_ndisc *nd, uint8_t *ret) {
 186         assert_return(nd, -EINVAL);
 187         assert_return(ret, -EINVAL);
 188
 189         if (nd->hop_limit == 0)
 190                 return -ENODATA;
 191
 192         *ret = nd->hop_limit;
 193         return 0;
 194 }
 195
 196 static int ndisc_handle_datagram(sd_ndisc *nd, sd_ndisc_router *rt) {
 197         int r;
 198
 199         assert(nd);
 200         assert(rt);
 201
 202         r = ndisc_router_parse(rt);
 203         if (r == -EBADMSG) /* Bad packet */
 204                 return 0;
 205         if (r < 0)
 206                 return 0;
 207
 208         /* Update global variables we keep */
 209         if (rt->mtu > 0)
 210                 nd->mtu = rt->mtu;
 211         if (rt->hop_limit > 0)
 212                 nd->hop_limit = rt->hop_limit;
 213
 214         log_ndisc("Received Router Advertisement: flags %s preference %s lifetime %" PRIu16 " sec",
 215                   rt->flags & ND_RA_FLAG_MANAGED ? "MANAGED" : rt->flags & ND_RA_FLAG_OTHER ? "OTHER" : "none",
 216                   rt->preference == SD_NDISC_PREFERENCE_HIGH ? "high" : rt->preference == SD_NDISC_PREFERENCE_LOW ? "low" : "medium",
 217                   rt->lifetime);
 218
 219         ndisc_callback(nd, SD_NDISC_EVENT_ROUTER, rt);
 220         return 0;
 221 }
 222
 223 static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 224         _cleanup_(sd_ndisc_router_unrefp) sd_ndisc_router *rt = NULL;
 225         sd_ndisc *nd = userdata;
 226         union {
 227                 struct cmsghdr cmsghdr;
 228                 uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
 229                             CMSG_SPACE(sizeof(struct timeval))];
 230         } control = {};
 231         struct iovec iov = {};
 232         union sockaddr_union sa = {};
 233         struct msghdr msg = {
 234                 .msg_name = &sa.sa,
 235                 .msg_namelen = sizeof(sa),
 236                 .msg_iov = &iov,
 237                 .msg_iovlen = 1,
 238                 .msg_control = &control,
 239                 .msg_controllen = sizeof(control),
 240         };
 241         struct cmsghdr *cmsg;
 242         ssize_t len, buflen;
 243
 244         assert(s);
 245         assert(nd);
 246         assert(nd->event);
 247
 248         buflen = next_datagram_size_fd(fd);
 249         if (buflen < 0)
 250                 return log_ndisc_errno(buflen, "Failed to determine datagram size to read: %m");
 251
 252         rt = ndisc_router_new(buflen);
 253         if (!rt)
 254                 return -ENOMEM;
 255
 256         iov.iov_base = NDISC_ROUTER_RAW(rt);
 257         iov.iov_len = rt->raw_size;
 258
 259         len = recvmsg(fd, &msg, MSG_DONTWAIT);
 260         if (len < 0) {
 261                 if (errno == EAGAIN || errno == EINTR)
 262                         return 0;
 263
 264                 return log_ndisc_errno(errno, "Could not receive message from ICMPv6 socket: %m");
 265         }
 266
 267         if ((size_t) len != rt->raw_size) {
 268                 log_ndisc("Packet size mismatch.");
 269                 return -EINVAL;
 270         }
 271
 272         if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
 273             sa.in6.sin6_family == AF_INET6)  {
 274
 275                 if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr) <= 0) {
 276                         _cleanup_free_ char *addr = NULL;
 277
 278                         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr, &addr);
 279                         log_ndisc("Received RA from non-link-local address %s. Ignoring.", strna(addr));
 280                         return 0;
 281                 }
 282
 283                 rt->address = sa.in6.sin6_addr;
 284
 285         } else if (msg.msg_namelen > 0) {
 286                 log_ndisc("Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t) msg.msg_namelen);
 287                 return -EINVAL;
 288         }
 289
 290         /* namelen == 0 only happens when running the test-suite over a socketpair */
 291
 292         assert(!(msg.msg_flags & MSG_CTRUNC));
 293         assert(!(msg.msg_flags & MSG_TRUNC));
 294
 295         CMSG_FOREACH(cmsg, &msg) {
 296                 if (cmsg->cmsg_level == SOL_IPV6 &&
 297                     cmsg->cmsg_type == IPV6_HOPLIMIT &&
 298                     cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
 299                         int hops = *(int*) CMSG_DATA(cmsg);
 300
 301                         if (hops != 255) {
 302                                 log_ndisc("Received RA with invalid hop limit %d. Ignoring.", hops);
 303                                 return 0;
 304                         }
 305                 }
 306
 307                 if (cmsg->cmsg_level == SOL_SOCKET &&
 308                     cmsg->cmsg_type == SO_TIMESTAMP &&
 309                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
 310                         triple_timestamp_from_realtime(&rt->timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
 311         }
 312
 313         if (!triple_timestamp_is_set(&rt->timestamp))
 314                 triple_timestamp_get(&rt->timestamp);
 315
 316         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 317
 318         return ndisc_handle_datagram(nd, rt);
 319 }
 320
 321 static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
 322         sd_ndisc *nd = userdata;
 323         usec_t time_now, next_timeout;
 324         int r;
 325
 326         assert(s);
 327         assert(nd);
 328         assert(nd->event);
 329
 330         if (nd->nd_sent >= NDISC_MAX_ROUTER_SOLICITATIONS) {
 331                 nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 332                 ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
 333                 return 0;
 334         }
 335
 336         r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
 337         if (r < 0) {
 338                 log_ndisc_errno(r, "Error sending Router Solicitation: %m");
 339                 goto fail;
 340         }
 341
 342         log_ndisc("Sent Router Solicitation");
 343         nd->nd_sent++;
 344
 345         assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
 346         next_timeout = time_now + NDISC_ROUTER_SOLICITATION_INTERVAL;
 347
 348         r = sd_event_source_set_time(nd->timeout_event_source, next_timeout);
 349         if (r < 0) {
 350                 log_ndisc_errno(r, "Error updating timer: %m");
 351                 goto fail;
 352         }
 353
 354         r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
 355         if (r < 0) {
 356                 log_ndisc_errno(r, "Error reenabling timer: %m");
 357                 goto fail;
 358         }
 359
 360         return 0;
 361
 362 fail:
 363         sd_ndisc_stop(nd);
 364         return 0;
 365 }
 366
 367 _public_ int sd_ndisc_stop(sd_ndisc *nd) {
 368         assert_return(nd, -EINVAL);
 369
 370         if (nd->fd < 0)
 371                 return 0;
 372
 373         log_ndisc("Stopping IPv6 Router Solicitation client");
 374
 375         ndisc_reset(nd);
 376         return 1;
 377 }
 378
 379 _public_ int sd_ndisc_start(sd_ndisc *nd) {
 380         int r;
 381
 382         assert_return(nd, -EINVAL);
 383         assert_return(nd->event, -EINVAL);
 384         assert_return(nd->ifindex > 0, -EINVAL);
 385
 386         if (nd->fd >= 0)
 387                 return 0;
 388
 389         assert(!nd->recv_event_source);
 390         assert(!nd->timeout_event_source);
 391
 392         nd->fd = icmp6_bind_router_solicitation(nd->ifindex);
 393         if (nd->fd < 0)
 394                 return nd->fd;
 395
 396         r = sd_event_add_io(nd->event, &nd->recv_event_source, nd->fd, EPOLLIN, ndisc_recv, nd);
 397         if (r < 0)
 398                 goto fail;
 399
 400         r = sd_event_source_set_priority(nd->recv_event_source, nd->event_priority);
 401         if (r < 0)
 402                 goto fail;
 403
 404         (void) sd_event_source_set_description(nd->recv_event_source, "ndisc-receive-message");
 405
 406         r = sd_event_add_time(nd->event, &nd->timeout_event_source, clock_boottime_or_monotonic(), 0, 0, ndisc_timeout, nd);
 407         if (r < 0)
 408                 goto fail;
 409
 410         r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
 411         if (r < 0)
 412                 goto fail;
 413
 414         (void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout");
 415
 416         log_ndisc("Started IPv6 Router Solicitation client");
 417         return 1;
 418
 419 fail:
 420         ndisc_reset(nd);
 421         return r;
 422 }