src/radv.c

   1 /* dnsmasq is Copyright (c) 2000-2012 Simon Kelley
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 dated June, 1991, or
   6    (at your option) version 3 dated 29 June, 2007.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12
  13    You should have received a copy of the GNU General Public License
  14    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16
  17
  18 /* NB. This code may be called during a DHCPv4 transaction which is in ping-wait
  19    It therefore cannot use any DHCP buffer resources except outpacket, which is
  20    not used by DHCPv4 code. */
  21
  22 #include "dnsmasq.h"
  23 #include <netinet/icmp6.h>
  24
  25 #ifdef HAVE_DHCP6
  26
  27 struct ra_param {
  28   int ind, managed, found_context, first;
  29   char *if_name;
  30   struct in6_addr link_local;
  31 };
  32
  33 struct search_param {
  34   time_t now; int iface;
  35 };
  36
  37 static void send_ra(int iface, char *iface_name, struct in6_addr *dest);
  38 static int add_prefixes(struct in6_addr *local,  int prefix,
  39                         int scope, int if_index, int dad, void *vparam);
  40 static int iface_search(struct in6_addr *local,  int prefix,
  41                         int scope, int if_index, int dad, void *vparam);
  42 static int add_lla(int index, unsigned int type, char *mac, size_t maclen, void *parm);
  43
  44 static int hop_limit;
  45 static time_t ra_short_period_start;
  46
  47 void ra_init(time_t now)
  48 {
  49   struct dhcp_context *context;
  50   struct icmp6_filter filter;
  51   int fd;
  52 #if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
  53   int class = IPTOS_CLASS_CS6;
  54 #endif
  55   int val = 255; /* radvd uses this value */
  56   size_t len = sizeof(int);
  57
  58   ICMP6_FILTER_SETBLOCKALL(&filter);
  59   ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
  60   ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
  61
  62   if ((fd = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) == -1 ||
  63       getsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hop_limit, &len) ||
  64 #if defined(IP_TOS) && defined(IPTOS_CLASS_CS6)
  65       setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS, &class, sizeof(class)) == -1 ||
  66 #endif
  67       !fix_fd(fd) ||
  68       !set_ipv6pktinfo(fd) ||
  69       setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val)) ||
  70       setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val)) ||
  71       setsockopt(fd, IPPROTO_ICMPV6, ICMP6_FILTER, &filter, sizeof(filter)) == -1)
  72     die (_("cannot create ICMPv6 socket: %s"), NULL, EC_BADNET);
  73
  74    daemon->icmp6fd = fd;
  75
  76    /* link the DHCP6 contexts to the ra-only ones so we can traverse them all
  77       from ->ra_contexts, but only the non-ra-onlies from ->dhcp6 */
  78    if (!daemon->ra_contexts)
  79      daemon->ra_contexts = daemon->dhcp6;
  80    else
  81      {
  82        for (context = daemon->ra_contexts; context->next; context = context->next);
  83        context->next = daemon->dhcp6;
  84      }
  85
  86    if (!daemon->dhcp6)
  87      die(_("cannot do router advertisement unless DHCPv6 is enabled"), NULL, EC_BADCONF);
  88
  89    ra_start_unsolicted(now);
  90 }
  91
  92 void ra_start_unsolicted(time_t now)
  93 {
  94    struct dhcp_context *context;
  95
  96    /* init timers so that we do ra's for all soon. some ra_times will end up zeroed
  97      if it's not appropriate to advertise those contexts.
  98      This gets re-called on a netlink route-change to re-do the advertisement
  99      and pick up new interfaces */
 100
 101    /* range 0 - 5 */
 102    for (context = daemon->ra_contexts; context; context = context->next)
 103      context->ra_time = now + (rand16()/13000);
 104
 105    /* re-do ras after a short time, in case the first gets lost.
 106       This is reset once that's done. */
 107    ra_short_period_start = now;
 108 }
 109
 110 void icmp6_packet(void)
 111 {
 112   char interface[IF_NAMESIZE+1];
 113   ssize_t sz;
 114   int if_index = 0;
 115   struct cmsghdr *cmptr;
 116   struct msghdr msg;
 117   union {
 118     struct cmsghdr align; /* this ensures alignment */
 119     char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
 120   } control_u;
 121   struct sockaddr_in6 from;
 122   unsigned char *p;
 123   char *mac = "";
 124   struct iname *tmp;
 125   struct dhcp_context *context;
 126
 127   /* Note: use outpacket for input buffer */
 128   msg.msg_control = control_u.control6;
 129   msg.msg_controllen = sizeof(control_u);
 130   msg.msg_flags = 0;
 131   msg.msg_name = &from;
 132   msg.msg_namelen = sizeof(from);
 133   msg.msg_iov = &daemon->outpacket;
 134   msg.msg_iovlen = 1;
 135
 136   if ((sz = recv_dhcp_packet(daemon->icmp6fd, &msg)) == -1 || sz < 8)
 137     return;
 138
 139   for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
 140     if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo)
 141       {
 142         union {
 143           unsigned char *c;
 144           struct in6_pktinfo *p;
 145         } p;
 146         p.c = CMSG_DATA(cmptr);
 147
 148         if_index = p.p->ipi6_ifindex;
 149       }
 150
 151   if (!indextoname(daemon->icmp6fd, if_index, interface))
 152     return;
 153
 154   if (!iface_check(AF_LOCAL, NULL, interface))
 155     return;
 156
 157   for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
 158     if (tmp->name && (strcmp(tmp->name, interface) == 0))
 159       return;
 160
 161   /* weird libvirt-inspired access control */
 162   for (context = daemon->dhcp6; context; context = context->next)
 163     if (!context->interface || strcmp(context->interface, interface) == 0)
 164       break;
 165
 166   if (!context)
 167     return;
 168
 169   p = (unsigned char *)daemon->outpacket.iov_base;
 170
 171   if (p[0] != ICMP6_ROUTER_SOLICIT || p[1] != 0)
 172     return;
 173
 174   /* look for link-layer address option for logging */
 175   if (sz >= 16 && p[8] == ICMP6_OPT_SOURCE_MAC && (p[9] * 8) + 8 <= sz)
 176     {
 177       print_mac(daemon->namebuff, &p[10], (p[9] * 8) - 2);
 178       mac = daemon->namebuff;
 179     }
 180
 181   my_syslog(MS_DHCP | LOG_INFO, "RTR-SOLICIT(%s) %s", interface, mac);
 182
 183   send_ra(if_index, interface, &from.sin6_addr);
 184 }
 185
 186 static void send_ra(int iface, char *iface_name, struct in6_addr *dest)
 187 {
 188   struct ra_packet *ra;
 189   struct ra_param parm;
 190   struct ifreq ifr;
 191   struct sockaddr_in6 addr;
 192   struct dhcp_context *context;
 193
 194   save_counter(0);
 195   ra = expand(sizeof(struct ra_packet));
 196
 197   ra->type = ICMP6_ROUTER_ADVERT;
 198   ra->code = 0;
 199   ra->hop_limit = hop_limit;
 200   ra->flags = 0;
 201   ra->lifetime = htons(1800); /* AdvDefaultLifetime*/
 202   ra->reachable_time = 0;
 203   ra->retrans_time = 0;
 204
 205   parm.ind = iface;
 206   parm.managed = 0;
 207   parm.found_context = 0;
 208   parm.if_name = iface_name;
 209   parm.first = 1;
 210
 211   for (context = daemon->ra_contexts; context; context = context->next)
 212     context->flags &= ~CONTEXT_RA_DONE;
 213
 214   if (!iface_enumerate(AF_INET6, &parm, add_prefixes) ||
 215       !parm.found_context)
 216     return;
 217
 218   strncpy(ifr.ifr_name, iface_name, IF_NAMESIZE);
 219
 220   if (ioctl(daemon->icmp6fd, SIOCGIFMTU, &ifr) != -1)
 221     {
 222       put_opt6_char(ICMP6_OPT_MTU);
 223       put_opt6_char(1);
 224       put_opt6_short(0);
 225       put_opt6_long(ifr.ifr_mtu);
 226     }
 227
 228   iface_enumerate(AF_LOCAL, &iface, add_lla);
 229
 230   /* RDNSS, RFC 6106 */
 231   put_opt6_char(ICMP6_OPT_RDNSS);
 232   put_opt6_char(3);
 233   put_opt6_short(0);
 234   put_opt6_long(1800); /* lifetime - twice RA retransmit */
 235   put_opt6(&parm.link_local, IN6ADDRSZ);
 236
 237
 238   /* set managed bits unless we're providing only RA on this link */
 239   if (parm.managed)
 240     ra->flags = 0xc0;
 241
 242   /* decide where we're sending */
 243   memset(&addr, 0, sizeof(addr));
 244   addr.sin6_family = AF_INET6;
 245   addr.sin6_port = htons(IPPROTO_ICMPV6);
 246   if (dest)
 247     {
 248       memcpy(&addr.sin6_addr, dest, sizeof(struct in6_addr));
 249       if (IN6_IS_ADDR_LINKLOCAL(dest) ||
 250           IN6_IS_ADDR_MC_LINKLOCAL(dest))
 251         addr.sin6_scope_id = iface;
 252     }
 253   else
 254     inet_pton(AF_INET6, ALL_HOSTS, &addr.sin6_addr);
 255
 256   send_from(daemon->icmp6fd, 0, daemon->outpacket.iov_base, save_counter(0),
 257             (union mysockaddr *)&addr, (struct all_addr *)&parm.link_local, iface);
 258
 259 }
 260
 261 static int add_prefixes(struct in6_addr *local,  int prefix,
 262                         int scope, int if_index, int dad, void *vparam)
 263 {
 264   struct dhcp_context *context, *tmp;
 265   struct ra_param *param = vparam;
 266   struct prefix_opt *opt;
 267
 268   (void)scope; /* warning */
 269   (void)dad;
 270
 271   if (if_index == param->ind)
 272     {
 273       if (IN6_IS_ADDR_LINKLOCAL(local))
 274         param->link_local = *local;
 275       else if (!IN6_IS_ADDR_LOOPBACK(local) &&
 276                !IN6_IS_ADDR_LINKLOCAL(local) &&
 277                !IN6_IS_ADDR_MULTICAST(local))
 278         {
 279           for (context = daemon->ra_contexts; context; context = context->next)
 280             if (prefix == context->prefix &&
 281                 is_same_net6(local, &context->start6, prefix) &&
 282                 is_same_net6(local, &context->end6, prefix))
 283               {
 284                 if (!(context->flags & CONTEXT_RA_ONLY))
 285                   param->managed = 1;
 286
 287                 if (context->flags & CONTEXT_RA_DONE)
 288                   continue;
 289
 290                 /* subsequent prefixes on the same interface don't need timers */
 291                 if (!param->first)
 292                   context->ra_time = 0;
 293                 param->first = 0;
 294                 param->found_context = 1;
 295                 context->flags |= CONTEXT_RA_DONE;
 296
 297                 /* mark this subnet and duplicates: as done. */
 298                 for (tmp = context->next; tmp; tmp = tmp->next)
 299                   if (tmp->prefix == prefix &&
 300                       is_same_net6(local, &tmp->start6, prefix) &&
 301                       is_same_net6(local, &tmp->end6, prefix))
 302                     {
 303                       tmp->flags |= CONTEXT_RA_DONE;
 304                       context->ra_time = 0;
 305                     }
 306
 307                 if ((opt = expand(sizeof(struct prefix_opt))))
 308                   {
 309                     u64 addrpart = addr6part(&context->start6);
 310                     u64 mask = (prefix == 64) ? (u64)-1LL : (1LLU << (128 - prefix)) - 1LLU;
 311                     unsigned int time = context->lease_time;
 312
 313                     /* lifetimes must be min 2 hrs, by RFC 2462 */
 314                     if (time < 7200)
 315                       time = 7200;
 316
 317                     opt->type = ICMP6_OPT_PREFIX;
 318                     opt->len = 4;
 319                     opt->prefix_len = prefix;
 320                     /* autonomous only is we're not doing dhcp */
 321                     opt->flags = (context->flags & CONTEXT_RA_ONLY) ? 0xc0 : 0x00;
 322                     opt->valid_lifetime = opt->preferred_lifetime = htonl(time);
 323                     opt->reserved = 0;
 324
 325                     opt->prefix = context->start6;
 326                     setaddr6part(&opt->prefix, addrpart & ~mask);
 327
 328                     inet_ntop(AF_INET6, &opt->prefix, daemon->addrbuff, ADDRSTRLEN);
 329                     my_syslog(MS_DHCP | LOG_INFO, "RTR-ADVERT(%s) %s", param->if_name, daemon->addrbuff);
 330                   }
 331               }
 332         }
 333     }
 334   return 1;
 335 }
 336
 337 static int add_lla(int index, unsigned int type, char *mac, size_t maclen, void *parm)
 338 {
 339   (void)type;
 340
 341   if (index == *((int *)parm))
 342     {
 343       /* size is in units of 8 octets and includes type and length (2 bytes)
 344          add 7 to round up */
 345       int len = (maclen + 9) >> 3;
 346       unsigned char *p = expand(len << 3);
 347       memset(p, 0, len << 3);
 348       *p++ = ICMP6_OPT_SOURCE_MAC;
 349       *p++ = len;
 350       memcpy(p, mac, maclen);
 351
 352       return 0;
 353     }
 354
 355   return 1;
 356 }
 357
 358 time_t periodic_ra(time_t now)
 359 {
 360   struct search_param param;
 361   struct dhcp_context *context;
 362   time_t next_event;
 363   char interface[IF_NAMESIZE+1];
 364
 365   param.now = now;
 366
 367   while (1)
 368     {
 369       /* find overdue events, and time of first future event */
 370       for (next_event = 0, context = daemon->ra_contexts; context; context = context->next)
 371         if (context->ra_time != 0)
 372           {
 373             if (difftime(context->ra_time, now) < 0.0)
 374               break; /* overdue */
 375
 376             if (next_event == 0 || difftime(next_event, context->ra_time + 2) > 0.0)
 377               next_event = context->ra_time + 2;
 378           }
 379
 380       /* none overdue */
 381       if (!context)
 382         break;
 383
 384       /* There's a context overdue, but we can't find an interface
 385          associated with it, because it's for a subnet we dont
 386          have an interface on. Probably we're doing DHCP on
 387          a remote subnet via a relay. Zero the timer, since we won't
 388          ever be able to send ra's and satistfy it. */
 389       if (iface_enumerate(AF_INET6, &param, iface_search))
 390         context->ra_time = 0;
 391       else if (indextoname(daemon->icmp6fd, param.iface, interface))
 392         send_ra(param.iface, interface, NULL);
 393     }
 394
 395   return next_event;
 396 }
 397
 398 static int iface_search(struct in6_addr *local,  int prefix,
 399                         int scope, int if_index, int dad, void *vparam)
 400 {
 401   struct search_param *param = vparam;
 402   struct dhcp_context *context;
 403
 404   (void)scope;
 405   (void)dad;
 406
 407   for (context = daemon->ra_contexts; context; context = context->next)
 408     if (prefix == context->prefix &&
 409         is_same_net6(local, &context->start6, prefix) &&
 410         is_same_net6(local, &context->end6, prefix))
 411       if (context->ra_time != 0 && difftime(context->ra_time, param->now) < 0.0)
 412         {
 413           /* found an interface that's overdue for RA determine new
 414              timeout value and zap other contexts on the same interface
 415              so they don't timeout independently .*/
 416           param->iface = if_index;
 417
 418           if (difftime(param->now, ra_short_period_start) < 60.0)
 419             /* range 5 - 20 */
 420             context->ra_time = param->now + 5 + (rand16()/4400);
 421           else
 422             /* range 450 - 600 */
 423             context->ra_time = param->now + 450 + (rand16()/440);
 424
 425           return 0; /* found, abort */
 426         }
 427
 428   return 1; /* keep searching */
 429 }
 430
 431 #endif