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
  25 #include <linux/fib_rules.h>
  26
  27 #include "relayd.h"
  28
  29 static struct uloop_fd rtnl_sock;
  30 static unsigned int rtnl_seq, rtnl_dump_seq;
  31 int route_table = 16800;
  32
  33 static void rtnl_flush(void)
  34 {
  35         int fd;
  36
  37         fd = open("/proc/sys/net/ipv4/route/flush", O_WRONLY);
  38         if (fd < 0)
  39                 return;
  40
  41         write(fd, "-1", 2);
  42         close(fd);
  43 }
  44
  45 enum {
  46         RULE_F_ADD = (1 << 0),
  47         RULE_F_DEFGW_WORKAROUND = (1 << 1),
  48 };
  49
  50 static void
  51 rtnl_rule_request(struct relayd_interface *rif, int flags)
  52 {
  53         static struct {
  54                 struct nlmsghdr nl;
  55                 struct rtmsg rt;
  56                 struct {
  57                         struct rtattr rta;
  58                         int table;
  59                 } __packed table;
  60                 struct {
  61                         struct rtattr rta;
  62                         char ifname[IFNAMSIZ + 1];
  63                 } __packed dev;
  64         } __packed req = {
  65                 .rt = {
  66                         .rtm_family = AF_INET,
  67                         .rtm_table = RT_TABLE_UNSPEC,
  68                         .rtm_scope = RT_SCOPE_UNIVERSE,
  69                         .rtm_protocol = RTPROT_BOOT,
  70                 },
  71                 .table.rta = {
  72                         .rta_type = FRA_TABLE,
  73                         .rta_len = sizeof(req.table),
  74                 },
  75         };
  76
  77         int padding = sizeof(req.dev.ifname);
  78
  79         if (!(flags & RULE_F_DEFGW_WORKAROUND)) {
  80                 req.dev.rta.rta_type = FRA_IFNAME;
  81                 padding -= strlen(rif->ifname) + 1;
  82                 strcpy(req.dev.ifname, rif->ifname);
  83                 req.dev.rta.rta_len = sizeof(req.dev.rta) + strlen(rif->ifname) + 1;
  84         } else {
  85                 req.dev.rta.rta_type = FRA_PRIORITY;
  86                 req.dev.rta.rta_len = sizeof(req.dev.rta) + sizeof(uint32_t);
  87                 padding -= sizeof(uint32_t);
  88                 *((uint32_t *) &req.dev.ifname) = 1;
  89         }
  90         req.table.table = rif->rt_table;
  91         req.nl.nlmsg_len = sizeof(req) - padding;
  92
  93         req.nl.nlmsg_flags = NLM_F_REQUEST;
  94         if (flags & RULE_F_ADD) {
  95                 req.nl.nlmsg_type = RTM_NEWRULE;
  96                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_EXCL;
  97
  98                 req.rt.rtm_type = RTN_UNICAST;
  99         } else {
 100                 req.nl.nlmsg_type = RTM_DELRULE;
 101                 req.rt.rtm_type = RTN_UNSPEC;
 102         }
 103
 104         send(rtnl_sock.fd, &req, req.nl.nlmsg_len, 0);
 105         rtnl_flush();
 106 }
 107
 108
 109 static void
 110 rtnl_route_request(struct relayd_interface *rif, struct relayd_host *host,
 111                    struct relayd_route *route, bool add)
 112 {
 113         static struct {
 114                 struct nlmsghdr nl;
 115                 struct rtmsg rt;
 116                 struct {
 117                         struct rtattr rta;
 118                         uint8_t ipaddr[4];
 119                 } __packed dst;
 120                 struct {
 121                         struct rtattr rta;
 122                         int table;
 123                 } __packed table;
 124                 struct {
 125                         struct rtattr rta;
 126                         int ifindex;
 127                 } __packed dev;
 128                 struct {
 129                         struct rtattr rta;
 130                         uint8_t ipaddr[4];
 131                 } __packed gw;
 132         } __packed req = {
 133                 .rt = {
 134                         .rtm_family = AF_INET,
 135                         .rtm_dst_len = 32,
 136                         .rtm_table = RT_TABLE_MAIN,
 137                 },
 138                 .table.rta = {
 139                         .rta_type = RTA_TABLE,
 140                         .rta_len = sizeof(req.table),
 141                 },
 142                 .dst.rta = {
 143                         .rta_len = sizeof(req.dst),
 144                 },
 145                 .dev.rta = {
 146                         .rta_type = RTA_OIF,
 147                         .rta_len = sizeof(req.dev),
 148                 },
 149                 .gw.rta = {
 150                         .rta_type = RTA_GATEWAY,
 151                         .rta_len = sizeof(req.gw),
 152                 },
 153         };
 154         int pktlen = sizeof(req);
 155
 156         req.dev.ifindex = host->rif->sll.sll_ifindex;
 157         req.table.table = rif->rt_table;
 158
 159         req.nl.nlmsg_flags = NLM_F_REQUEST;
 160         if (add) {
 161                 req.nl.nlmsg_type = RTM_NEWROUTE;
 162                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
 163
 164                 req.rt.rtm_protocol = RTPROT_BOOT;
 165                 if (route) {
 166                         req.rt.rtm_scope = RT_SCOPE_UNIVERSE;
 167                 } else {
 168                         req.rt.rtm_scope = RT_SCOPE_LINK;
 169                 }
 170                 req.rt.rtm_type = RTN_UNICAST;
 171         } else {
 172                 req.nl.nlmsg_type = RTM_DELROUTE;
 173                 req.rt.rtm_scope = RT_SCOPE_NOWHERE;
 174         }
 175
 176         req.dst.rta.rta_type = RTA_DST;
 177         if (route) {
 178                 DPRINTF(2, "%s: add route to "IP_FMT"/%d via "IP_FMT"\n",
 179                         host->rif->ifname, IP_BUF(route->dest), route->mask, IP_BUF(host->ipaddr));
 180                 if (!route->mask) {
 181                         /* No DST -> reuse the DST attribute as the gateway attribute */
 182                         memcpy(req.dst.ipaddr, host->ipaddr, sizeof(req.dst.ipaddr));
 183                         req.dst.rta.rta_type = RTA_GATEWAY;
 184                         pktlen -= sizeof(req.gw);
 185                         req.rt.rtm_dst_len = 0;
 186                 } else {
 187                         memcpy(req.gw.ipaddr, host->ipaddr, sizeof(req.gw.ipaddr));
 188                         memcpy(req.dst.ipaddr, route->dest, sizeof(req.dst.ipaddr));
 189                         req.rt.rtm_dst_len = route->mask;
 190                 }
 191         } else {
 192                 pktlen -= sizeof(req.gw);
 193                 req.rt.rtm_dst_len = 32;
 194                 memcpy(req.dst.ipaddr, host->ipaddr, sizeof(req.dst.ipaddr));
 195         }
 196
 197         req.nl.nlmsg_len = pktlen;
 198         if (route)
 199                 rtnl_rule_request(rif, RULE_F_DEFGW_WORKAROUND | RULE_F_ADD);
 200         send(rtnl_sock.fd, &req, pktlen, 0);
 201         if (route)
 202                 rtnl_rule_request(rif, RULE_F_DEFGW_WORKAROUND);
 203         rtnl_flush();
 204 }
 205
 206 void
 207 rtnl_route_set(struct relayd_host *host, struct relayd_route *route, bool add)
 208 {
 209         struct relayd_interface *rif;
 210
 211         list_for_each_entry(rif, &interfaces, list) {
 212                 if (rif == host->rif)
 213                         continue;
 214
 215                 rtnl_route_request(rif, host, route, add);
 216         }
 217 }
 218
 219 void relayd_add_interface_routes(struct relayd_interface *rif)
 220 {
 221         rif->rt_table = route_table++;
 222         rtnl_rule_request(rif, RULE_F_ADD);
 223 }
 224
 225 void relayd_del_interface_routes(struct relayd_interface *rif)
 226 {
 227         rtnl_rule_request(rif, 0);
 228 }
 229
 230 #ifndef NDA_RTA
 231 #define NDA_RTA(r) \
 232     ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ndmsg))))
 233 #endif
 234
 235 static void rtnl_parse_newneigh(struct nlmsghdr *h)
 236 {
 237         struct relayd_interface *rif = NULL;
 238         struct ndmsg *r = NLMSG_DATA(h);
 239         const uint8_t *lladdr = NULL;
 240         const uint8_t *ipaddr = NULL;
 241         struct rtattr *rta;
 242         int len;
 243
 244         if (r->ndm_family != AF_INET)
 245                 return;
 246
 247         list_for_each_entry(rif, &interfaces, list) {
 248                 if (rif->sll.sll_ifindex == r->ndm_ifindex)
 249                         goto found_interface;
 250         }
 251         return;
 252
 253 found_interface:
 254         len = h->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
 255         for (rta = NDA_RTA(r); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
 256                 switch(rta->rta_type) {
 257                 case NDA_LLADDR:
 258                         lladdr = RTA_DATA(rta);
 259                         break;
 260                 case NDA_DST:
 261                         ipaddr = RTA_DATA(rta);
 262                         break;
 263                 default:
 264                         break;
 265                 }
 266         }
 267
 268         if (!lladdr || !ipaddr || (r->ndm_state & (NUD_INCOMPLETE|NUD_FAILED)))
 269                 return;
 270
 271         if (!memcmp(lladdr, "\x00\x00\x00\x00\x00\x00", ETH_ALEN))
 272                 return;
 273
 274         DPRINTF(1, "%s: Found ARP cache entry for host "IP_FMT" ("MAC_FMT")\n",
 275                 rif->ifname, IP_BUF(ipaddr), MAC_BUF(lladdr));
 276         relayd_refresh_host(rif, lladdr, ipaddr);
 277 }
 278
 279 static void rtnl_parse_packet(void *data, int len)
 280 {
 281         struct nlmsghdr *h;
 282
 283         for (h = data; NLMSG_OK(h, len); h = NLMSG_NEXT(h, len)) {
 284                 if (h->nlmsg_type == NLMSG_DONE ||
 285                     h->nlmsg_type == NLMSG_ERROR)
 286                         return;
 287
 288                 if (h->nlmsg_seq != rtnl_dump_seq)
 289                         continue;
 290
 291                 if (h->nlmsg_type == RTM_NEWNEIGH)
 292                         rtnl_parse_newneigh(h);
 293         }
 294 }
 295
 296 static void rtnl_cb(struct uloop_fd *fd, unsigned int events)
 297 {
 298         struct sockaddr_nl nladdr;
 299         static uint8_t buf[16384];
 300         struct iovec iov = {
 301                 .iov_base = buf,
 302                 .iov_len = sizeof(buf),
 303         };
 304         struct msghdr msg = {
 305                 .msg_name = &nladdr,
 306                 .msg_namelen = sizeof(nladdr),
 307                 .msg_iov = &iov,
 308                 .msg_iovlen = 1,
 309         };
 310
 311         do {
 312                 int len;
 313
 314                 len = recvmsg(rtnl_sock.fd, &msg, 0);
 315                 if (len < 0) {
 316                         if (errno == EINTR)
 317                                 continue;
 318
 319                         return;
 320                 }
 321
 322                 if (!len)
 323                         break;
 324
 325                 if (nladdr.nl_pid != 0)
 326                         continue;
 327
 328                 rtnl_parse_packet(buf, len);
 329         } while (1);
 330 }
 331
 332 static void rtnl_dump_request(int nlmsg_type)
 333 {
 334         static struct {
 335                 struct nlmsghdr nlh;
 336                 struct rtgenmsg g;
 337         } req = {
 338                 .nlh = {
 339                         .nlmsg_len = sizeof(req),
 340                         .nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST,
 341                         .nlmsg_pid = 0,
 342                 },
 343                 .g.rtgen_family = AF_INET,
 344         };
 345         req.nlh.nlmsg_type = nlmsg_type;
 346         req.nlh.nlmsg_seq = rtnl_seq;
 347         send(rtnl_sock.fd, &req, sizeof(req), 0);
 348         rtnl_seq++;
 349 }
 350
 351 int relayd_rtnl_init(void)
 352 {
 353         struct sockaddr_nl snl_local;
 354
 355         rtnl_sock.fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 356         if (rtnl_sock.fd < 0) {
 357                 perror("socket(AF_NETLINK)");
 358                 return -1;
 359         }
 360
 361         snl_local.nl_family = AF_NETLINK;
 362
 363         if (bind(rtnl_sock.fd, (struct sockaddr *) &snl_local, sizeof(struct sockaddr_nl)) < 0) {
 364                 perror("bind");
 365                 close(rtnl_sock.fd);
 366                 return -1;
 367         }
 368
 369         rtnl_sock.cb = rtnl_cb;
 370         uloop_fd_add(&rtnl_sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 371
 372         rtnl_seq = time(NULL);
 373         rtnl_dump_seq = rtnl_seq;
 374         rtnl_dump_request(RTM_GETNEIGH);
 375
 376         return 0;
 377 }
 378
 379 void relayd_rtnl_done(void)
 380 {
 381         uloop_fd_delete(&rtnl_sock);
 382         close(rtnl_sock.fd);
 383 }