route.c

   1 /*
   2  *   Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
   3  *
   4  *   This program is free software; you can redistribute it and/or modify
   5  *   it under the terms of the GNU General Public License v2 as published by
   6  *   the Free Software Foundation.
   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, write to the Free Software
  15  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  16  */
  17
  18 #include <sys/socket.h>
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <errno.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24 #include <time.h>
  25
  26 #include <linux/fib_rules.h>
  27
  28 #include "relayd.h"
  29
  30 static struct uloop_fd rtnl_sock;
  31 static unsigned int rtnl_seq, rtnl_dump_seq;
  32 int route_table = 16800;
  33
  34 static void rtnl_flush(void)
  35 {
  36         int fd;
  37
  38         fd = open("/proc/sys/net/ipv4/route/flush", O_WRONLY);
  39         if (fd < 0)
  40                 return;
  41
  42         write(fd, "-1", 2);
  43         close(fd);
  44 }
  45
  46 enum {
  47         RULE_F_ADD = (1 << 0),
  48         RULE_F_DEFGW_WORKAROUND = (1 << 1),
  49 };
  50
  51 static int get_route_table(struct relayd_interface *rif)
  52 {
  53         if (rif)
  54                 return rif->rt_table;
  55         else
  56                 return local_route_table;
  57 }
  58
  59 static void
  60 rtnl_rule_request(struct relayd_interface *rif, int flags)
  61 {
  62         static struct {
  63                 struct nlmsghdr nl;
  64                 struct rtmsg rt;
  65                 struct {
  66                         struct rtattr rta;
  67                         int table;
  68                 } __packed table;
  69                 struct {
  70                         struct rtattr rta;
  71                         int prio;
  72                 } __packed prio;
  73                 struct {
  74                         struct rtattr rta;
  75                         char ifname[IFNAMSIZ + 1];
  76                 } __packed dev;
  77         } __packed req = {
  78                 .rt = {
  79                         .rtm_family = AF_INET,
  80                         .rtm_table = RT_TABLE_UNSPEC,
  81                         .rtm_scope = RT_SCOPE_UNIVERSE,
  82                         .rtm_protocol = RTPROT_BOOT,
  83                 },
  84                 .prio = {
  85                         .rta.rta_type = FRA_PRIORITY,
  86                         .rta.rta_len = sizeof(req.prio),
  87                         .prio = 2,
  88                 },
  89                 .table.rta = {
  90                         .rta_type = FRA_TABLE,
  91                         .rta_len = sizeof(req.table),
  92                 },
  93         };
  94         const char *ifname = "lo";
  95         int padding = sizeof(req.dev.ifname);
  96
  97         if (rif)
  98                 ifname = rif->ifname;
  99
 100         if (!(flags & RULE_F_DEFGW_WORKAROUND)) {
 101                 req.dev.rta.rta_type = FRA_IFNAME;
 102                 padding -= strlen(ifname) + 1;
 103                 strcpy(req.dev.ifname, ifname);
 104                 req.dev.rta.rta_len = sizeof(req.dev.rta) + strlen(ifname) + 1;
 105         } else {
 106                 padding = sizeof(req.dev);
 107                 req.prio.prio--;
 108         }
 109         req.table.table = get_route_table(rif);
 110         req.nl.nlmsg_len = sizeof(req) - padding;
 111
 112         req.nl.nlmsg_flags = NLM_F_REQUEST;
 113         if (flags & RULE_F_ADD) {
 114                 req.nl.nlmsg_type = RTM_NEWRULE;
 115                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_EXCL;
 116
 117                 req.rt.rtm_type = RTN_UNICAST;
 118         } else {
 119                 req.nl.nlmsg_type = RTM_DELRULE;
 120                 req.rt.rtm_type = RTN_UNSPEC;
 121         }
 122
 123         send(rtnl_sock.fd, &req, req.nl.nlmsg_len, 0);
 124         rtnl_flush();
 125 }
 126
 127 struct rtnl_addr {
 128         struct rtattr rta;
 129         uint8_t ipaddr[4];
 130 } __packed;
 131
 132 static struct rtnl_addr *
 133 rtnl_add_addr(struct rtnl_addr *addr, int *len, int type, const uint8_t *ipaddr)
 134 {
 135         addr->rta.rta_type = type;
 136         memcpy(addr->ipaddr, ipaddr, 4);
 137         *len += sizeof(*addr);
 138         return addr + 1;
 139 }
 140
 141 static void
 142 rtnl_route_request(struct relayd_interface *rif, struct relayd_host *host,
 143                    struct relayd_route *route, bool add)
 144 {
 145         static struct {
 146                 struct nlmsghdr nl;
 147                 struct rtmsg rt;
 148                 struct {
 149                         struct rtattr rta;
 150                         int table;
 151                 } __packed table;
 152                 struct {
 153                         struct rtattr rta;
 154                         int ifindex;
 155                 } __packed dev;
 156                 struct rtnl_addr addr[3];
 157         } __packed req = {
 158                 .rt = {
 159                         .rtm_family = AF_INET,
 160                         .rtm_dst_len = 32,
 161                         .rtm_table = RT_TABLE_MAIN,
 162                 },
 163                 .table.rta = {
 164                         .rta_type = RTA_TABLE,
 165                         .rta_len = sizeof(req.table),
 166                 },
 167                 .dev.rta = {
 168                         .rta_type = RTA_OIF,
 169                         .rta_len = sizeof(req.dev),
 170                 },
 171                 .addr[0].rta.rta_len = sizeof(struct rtnl_addr),
 172                 .addr[1].rta.rta_len = sizeof(struct rtnl_addr),
 173                 .addr[2].rta.rta_len = sizeof(struct rtnl_addr),
 174         };
 175         int pktlen = sizeof(req) - sizeof(req.addr);
 176         struct rtnl_addr *addr = &req.addr[0];
 177         const char *ifname = "loopback";
 178
 179         req.dev.ifindex = host->rif->sll.sll_ifindex;
 180         req.table.table = get_route_table(rif);
 181
 182         req.nl.nlmsg_flags = NLM_F_REQUEST;
 183         if (add) {
 184                 req.nl.nlmsg_type = RTM_NEWROUTE;
 185                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
 186
 187                 req.rt.rtm_protocol = RTPROT_BOOT;
 188                 if (route) {
 189                         req.rt.rtm_scope = RT_SCOPE_UNIVERSE;
 190                 } else {
 191                         req.rt.rtm_scope = RT_SCOPE_LINK;
 192                 }
 193                 req.rt.rtm_type = RTN_UNICAST;
 194         } else {
 195                 req.nl.nlmsg_type = RTM_DELROUTE;
 196                 req.rt.rtm_scope = RT_SCOPE_NOWHERE;
 197         }
 198
 199         if (rif)
 200                 ifname = rif->ifname;
 201
 202         if (route) {
 203                 DPRINTF(2, "%s: add route to "IP_FMT"/%d via "IP_FMT" (%s)\n", ifname,
 204                         IP_BUF(route->dest), route->mask, IP_BUF(host->ipaddr),
 205                         host->rif->ifname);
 206
 207                 req.rt.rtm_dst_len = route->mask;
 208                 if (route->mask)
 209                         addr = rtnl_add_addr(addr, &pktlen, RTA_DST, route->dest);
 210                 addr = rtnl_add_addr(addr, &pktlen, RTA_GATEWAY, host->ipaddr);
 211         } else {
 212                 DPRINTF(2, "%s: add host route to "IP_FMT" (%s)\n", ifname,
 213                         IP_BUF(host->ipaddr), host->rif->ifname);
 214                 addr = rtnl_add_addr(addr, &pktlen, RTA_DST, host->ipaddr);
 215                 req.rt.rtm_dst_len = 32;
 216         }
 217
 218         /* local route */
 219         if (!rif)
 220                 addr = rtnl_add_addr(addr, &pktlen, RTA_PREFSRC, local_addr);
 221
 222         req.nl.nlmsg_len = pktlen;
 223         if (route)
 224                 rtnl_rule_request(rif, RULE_F_DEFGW_WORKAROUND | RULE_F_ADD);
 225         send(rtnl_sock.fd, &req, pktlen, 0);
 226         if (route)
 227                 rtnl_rule_request(rif, RULE_F_DEFGW_WORKAROUND);
 228         rtnl_flush();
 229 }
 230
 231 void
 232 rtnl_route_set(struct relayd_host *host, struct relayd_route *route, bool add)
 233 {
 234         struct relayd_interface *rif;
 235
 236         list_for_each_entry(rif, &interfaces, list) {
 237                 if (rif == host->rif)
 238                         continue;
 239
 240                 rtnl_route_request(rif, host, route, add);
 241         }
 242         if (local_route_table)
 243                 rtnl_route_request(NULL, host, route, add);
 244 }
 245
 246 void relayd_add_interface_routes(struct relayd_interface *rif)
 247 {
 248         rif->rt_table = route_table++;
 249         rtnl_rule_request(rif, RULE_F_ADD);
 250 }
 251
 252 void relayd_del_interface_routes(struct relayd_interface *rif)
 253 {
 254         rtnl_rule_request(rif, 0);
 255 }
 256
 257 #ifndef NDA_RTA
 258 #define NDA_RTA(r) \
 259     ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ndmsg))))
 260 #endif
 261
 262 static void rtnl_parse_newneigh(struct nlmsghdr *h)
 263 {
 264         struct relayd_interface *rif = NULL;
 265         struct ndmsg *r = NLMSG_DATA(h);
 266         const uint8_t *lladdr = NULL;
 267         const uint8_t *ipaddr = NULL;
 268         struct rtattr *rta;
 269         int len;
 270
 271         if (r->ndm_family != AF_INET)
 272                 return;
 273
 274         list_for_each_entry(rif, &interfaces, list) {
 275                 if (rif->sll.sll_ifindex == r->ndm_ifindex)
 276                         goto found_interface;
 277         }
 278         return;
 279
 280 found_interface:
 281         len = h->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
 282         for (rta = NDA_RTA(r); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
 283                 switch(rta->rta_type) {
 284                 case NDA_LLADDR:
 285                         lladdr = RTA_DATA(rta);
 286                         break;
 287                 case NDA_DST:
 288                         ipaddr = RTA_DATA(rta);
 289                         break;
 290                 default:
 291                         break;
 292                 }
 293         }
 294
 295         if (!lladdr || !ipaddr || (r->ndm_state & (NUD_INCOMPLETE|NUD_FAILED)))
 296                 return;
 297
 298         if (!memcmp(lladdr, "\x00\x00\x00\x00\x00\x00", ETH_ALEN))
 299                 return;
 300
 301         DPRINTF(1, "%s: Found ARP cache entry for host "IP_FMT" ("MAC_FMT")\n",
 302                 rif->ifname, IP_BUF(ipaddr), MAC_BUF(lladdr));
 303         relayd_refresh_host(rif, lladdr, ipaddr);
 304 }
 305
 306 static void rtnl_parse_packet(void *data, int len)
 307 {
 308         struct nlmsghdr *h;
 309
 310         for (h = data; NLMSG_OK(h, len); h = NLMSG_NEXT(h, len)) {
 311                 if (h->nlmsg_type == NLMSG_DONE ||
 312                     h->nlmsg_type == NLMSG_ERROR)
 313                         return;
 314
 315                 if (h->nlmsg_seq != rtnl_dump_seq)
 316                         continue;
 317
 318                 if (h->nlmsg_type == RTM_NEWNEIGH)
 319                         rtnl_parse_newneigh(h);
 320         }
 321 }
 322
 323 static void rtnl_cb(struct uloop_fd *fd, unsigned int events)
 324 {
 325         struct sockaddr_nl nladdr;
 326         static uint8_t buf[16384];
 327         struct iovec iov = {
 328                 .iov_base = buf,
 329                 .iov_len = sizeof(buf),
 330         };
 331         struct msghdr msg = {
 332                 .msg_name = &nladdr,
 333                 .msg_namelen = sizeof(nladdr),
 334                 .msg_iov = &iov,
 335                 .msg_iovlen = 1,
 336         };
 337
 338         do {
 339                 int len;
 340
 341                 len = recvmsg(rtnl_sock.fd, &msg, 0);
 342                 if (len < 0) {
 343                         if (errno == EINTR)
 344                                 continue;
 345
 346                         return;
 347                 }
 348
 349                 if (!len)
 350                         break;
 351
 352                 if (nladdr.nl_pid != 0)
 353                         continue;
 354
 355                 rtnl_parse_packet(buf, len);
 356         } while (1);
 357 }
 358
 359 static void rtnl_dump_request(int nlmsg_type)
 360 {
 361         static struct {
 362                 struct nlmsghdr nlh;
 363                 struct rtgenmsg g;
 364         } req = {
 365                 .nlh = {
 366                         .nlmsg_len = sizeof(req),
 367                         .nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST,
 368                         .nlmsg_pid = 0,
 369                 },
 370                 .g.rtgen_family = AF_INET,
 371         };
 372         req.nlh.nlmsg_type = nlmsg_type;
 373         req.nlh.nlmsg_seq = rtnl_seq;
 374         send(rtnl_sock.fd, &req, sizeof(req), 0);
 375         rtnl_seq++;
 376 }
 377
 378 int relayd_rtnl_init(void)
 379 {
 380         struct sockaddr_nl snl_local = {};
 381
 382         rtnl_sock.fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 383         if (rtnl_sock.fd < 0) {
 384                 perror("socket(AF_NETLINK)");
 385                 return -1;
 386         }
 387
 388         snl_local.nl_family = AF_NETLINK;
 389
 390         if (bind(rtnl_sock.fd, (struct sockaddr *) &snl_local, sizeof(struct sockaddr_nl)) < 0) {
 391                 perror("bind");
 392                 close(rtnl_sock.fd);
 393                 return -1;
 394         }
 395
 396         rtnl_sock.cb = rtnl_cb;
 397         uloop_fd_add(&rtnl_sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 398
 399         rtnl_seq = time(NULL);
 400         rtnl_dump_seq = rtnl_seq;
 401         rtnl_dump_request(RTM_GETNEIGH);
 402         rtnl_rule_request(NULL, RULE_F_ADD);
 403
 404         return 0;
 405 }
 406
 407 void relayd_rtnl_done(void)
 408 {
 409         rtnl_rule_request(NULL, 0);
 410         uloop_fd_delete(&rtnl_sock);
 411         close(rtnl_sock.fd);
 412 }