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         return mfree(nd);
 152 }
 153
 154 _public_ int sd_ndisc_new(sd_ndisc **ret) {
 155         _cleanup_(sd_ndisc_unrefp) sd_ndisc *nd = NULL;
 156
 157         assert_return(ret, -EINVAL);
 158
 159         nd = new0(sd_ndisc, 1);
 160         if (!nd)
 161                 return -ENOMEM;
 162
 163         nd->n_ref = 1;
 164         nd->fd = -1;
 165
 166         *ret = nd;
 167         nd = NULL;
 168
 169         return 0;
 170 }
 171
 172 _public_ int sd_ndisc_get_mtu(sd_ndisc *nd, uint32_t *mtu) {
 173         assert_return(nd, -EINVAL);
 174         assert_return(mtu, -EINVAL);
 175
 176         if (nd->mtu == 0)
 177                 return -ENODATA;
 178
 179         *mtu = nd->mtu;
 180         return 0;
 181 }
 182
 183 _public_ int sd_ndisc_get_hop_limit(sd_ndisc *nd, uint8_t *ret) {
 184         assert_return(nd, -EINVAL);
 185         assert_return(ret, -EINVAL);
 186
 187         if (nd->hop_limit == 0)
 188                 return -ENODATA;
 189
 190         *ret = nd->hop_limit;
 191         return 0;
 192 }
 193
 194 static int ndisc_handle_datagram(sd_ndisc *nd, sd_ndisc_router *rt) {
 195         int r;
 196
 197         assert(nd);
 198         assert(rt);
 199
 200         r = ndisc_router_parse(rt);
 201         if (r == -EBADMSG) /* Bad packet */
 202                 return 0;
 203         if (r < 0)
 204                 return 0;
 205
 206         /* Update global variables we keep */
 207         if (rt->mtu > 0)
 208                 nd->mtu = rt->mtu;
 209         if (rt->hop_limit > 0)
 210                 nd->hop_limit = rt->hop_limit;
 211
 212         log_ndisc("Received Router Advertisement: flags %s preference %s lifetime %" PRIu16 " sec",
 213                   rt->flags & ND_RA_FLAG_MANAGED ? "MANAGED" : rt->flags & ND_RA_FLAG_OTHER ? "OTHER" : "none",
 214                   rt->preference == SD_NDISC_PREFERENCE_HIGH ? "high" : rt->preference == SD_NDISC_PREFERENCE_LOW ? "low" : "medium",
 215                   rt->lifetime);
 216
 217         ndisc_callback(nd, SD_NDISC_EVENT_ROUTER, rt);
 218         return 0;
 219 }
 220
 221 static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 222         _cleanup_(sd_ndisc_router_unrefp) sd_ndisc_router *rt = NULL;
 223         sd_ndisc *nd = userdata;
 224         union {
 225                 struct cmsghdr cmsghdr;
 226                 uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
 227                             CMSG_SPACE(sizeof(struct timeval))];
 228         } control = {};
 229         struct iovec iov = {};
 230         union sockaddr_union sa = {};
 231         struct msghdr msg = {
 232                 .msg_name = &sa.sa,
 233                 .msg_namelen = sizeof(sa),
 234                 .msg_iov = &iov,
 235                 .msg_iovlen = 1,
 236                 .msg_control = &control,
 237                 .msg_controllen = sizeof(control),
 238         };
 239         struct cmsghdr *cmsg;
 240         ssize_t len, buflen;
 241
 242         assert(s);
 243         assert(nd);
 244         assert(nd->event);
 245
 246         buflen = next_datagram_size_fd(fd);
 247         if (buflen < 0)
 248                 return log_ndisc_errno(buflen, "Failed to determine datagram size to read: %m");
 249
 250         rt = ndisc_router_new(buflen);
 251         if (!rt)
 252                 return -ENOMEM;
 253
 254         iov.iov_base = NDISC_ROUTER_RAW(rt);
 255         iov.iov_len = rt->raw_size;
 256
 257         len = recvmsg(fd, &msg, MSG_DONTWAIT);
 258         if (len < 0) {
 259                 if (errno == EAGAIN || errno == EINTR)
 260                         return 0;
 261
 262                 return log_ndisc_errno(errno, "Could not receive message from ICMPv6 socket: %m");
 263         }
 264
 265         if ((size_t) len != rt->raw_size) {
 266                 log_ndisc("Packet size mismatch.");
 267                 return -EINVAL;
 268         }
 269
 270         if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
 271             sa.in6.sin6_family == AF_INET6)  {
 272
 273                 if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr) <= 0) {
 274                         _cleanup_free_ char *addr = NULL;
 275
 276                         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &sa.in6.sin6_addr, &addr);
 277                         log_ndisc("Received RA from non-link-local address %s. Ignoring.", strna(addr));
 278                         return 0;
 279                 }
 280
 281                 rt->address = sa.in6.sin6_addr;
 282
 283         } else if (msg.msg_namelen > 0) {
 284                 log_ndisc("Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t) msg.msg_namelen);
 285                 return -EINVAL;
 286         }
 287
 288         /* namelen == 0 only happens when running the test-suite over a socketpair */
 289
 290         assert(!(msg.msg_flags & MSG_CTRUNC));
 291         assert(!(msg.msg_flags & MSG_TRUNC));
 292
 293         CMSG_FOREACH(cmsg, &msg) {
 294                 if (cmsg->cmsg_level == SOL_IPV6 &&
 295                     cmsg->cmsg_type == IPV6_HOPLIMIT &&
 296                     cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
 297                         int hops = *(int*) CMSG_DATA(cmsg);
 298
 299                         if (hops != 255) {
 300                                 log_ndisc("Received RA with invalid hop limit %d. Ignoring.", hops);
 301                                 return 0;
 302                         }
 303                 }
 304
 305                 if (cmsg->cmsg_level == SOL_SOCKET &&
 306                     cmsg->cmsg_type == SO_TIMESTAMP &&
 307                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
 308                         triple_timestamp_from_realtime(&rt->timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
 309         }
 310
 311         if (!triple_timestamp_is_set(&rt->timestamp))
 312                 triple_timestamp_get(&rt->timestamp);
 313
 314         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 315
 316         return ndisc_handle_datagram(nd, rt);
 317 }
 318
 319 static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
 320         sd_ndisc *nd = userdata;
 321         usec_t time_now, next_timeout;
 322         int r;
 323
 324         assert(s);
 325         assert(nd);
 326         assert(nd->event);
 327
 328         if (nd->nd_sent >= NDISC_MAX_ROUTER_SOLICITATIONS) {
 329                 nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 330                 ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
 331                 return 0;
 332         }
 333
 334         r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
 335         if (r < 0) {
 336                 log_ndisc_errno(r, "Error sending Router Solicitation: %m");
 337                 goto fail;
 338         }
 339
 340         log_ndisc("Sent Router Solicitation");
 341         nd->nd_sent++;
 342
 343         assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
 344         next_timeout = time_now + NDISC_ROUTER_SOLICITATION_INTERVAL;
 345
 346         r = sd_event_source_set_time(nd->timeout_event_source, next_timeout);
 347         if (r < 0) {
 348                 log_ndisc_errno(r, "Error updating timer: %m");
 349                 goto fail;
 350         }
 351
 352         r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
 353         if (r < 0) {
 354                 log_ndisc_errno(r, "Error reenabling timer: %m");
 355                 goto fail;
 356         }
 357
 358         return 0;
 359
 360 fail:
 361         sd_ndisc_stop(nd);
 362         return 0;
 363 }
 364
 365 _public_ int sd_ndisc_stop(sd_ndisc *nd) {
 366         assert_return(nd, -EINVAL);
 367
 368         if (nd->fd < 0)
 369                 return 0;
 370
 371         log_ndisc("Stopping IPv6 Router Solicitation client");
 372
 373         ndisc_reset(nd);
 374         return 1;
 375 }
 376
 377 _public_ int sd_ndisc_start(sd_ndisc *nd) {
 378         int r;
 379
 380         assert_return(nd, -EINVAL);
 381         assert_return(nd->event, -EINVAL);
 382         assert_return(nd->ifindex > 0, -EINVAL);
 383
 384         if (nd->fd >= 0)
 385                 return 0;
 386
 387         assert(!nd->recv_event_source);
 388         assert(!nd->timeout_event_source);
 389
 390         nd->fd = icmp6_bind_router_solicitation(nd->ifindex);
 391         if (nd->fd < 0)
 392                 return nd->fd;
 393
 394         r = sd_event_add_io(nd->event, &nd->recv_event_source, nd->fd, EPOLLIN, ndisc_recv, nd);
 395         if (r < 0)
 396                 goto fail;
 397
 398         r = sd_event_source_set_priority(nd->recv_event_source, nd->event_priority);
 399         if (r < 0)
 400                 goto fail;
 401
 402         (void) sd_event_source_set_description(nd->recv_event_source, "ndisc-receive-message");
 403
 404         r = sd_event_add_time(nd->event, &nd->timeout_event_source, clock_boottime_or_monotonic(), 0, 0, ndisc_timeout, nd);
 405         if (r < 0)
 406                 goto fail;
 407
 408         r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
 409         if (r < 0)
 410                 goto fail;
 411
 412         (void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout");
 413
 414         log_ndisc("Started IPv6 Router Solicitation client");
 415         return 1;
 416
 417 fail:
 418         ndisc_reset(nd);
 419         return r;
 420 }