2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
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.
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.
20 #include <arpa/inet.h>
21 #include <sys/socket.h>
22 #include <net/ethernet.h>
23 #include <netinet/ip6.h>
24 #include <netinet/icmp6.h>
25 #include <netpacket/packet.h>
27 #include <linux/rtnetlink.h>
28 #include <linux/filter.h>
34 static void handle_solicit(void *addr, void *data, size_t len,
35 struct interface *iface);
36 static void handle_rtnetlink(void *addr, void *data, size_t len,
37 struct interface *iface);
38 static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict);
39 static void modify_neighbor(struct in6_addr *addr, struct interface *iface,
41 static ssize_t ping6(struct in6_addr *addr,
42 const struct interface *iface);
44 static struct list_head neighbors = LIST_HEAD_INIT(neighbors);
45 static size_t neighbor_count = 0;
46 static uint32_t rtnl_seqid = 0;
48 static int ping_socket = -1;
49 static struct odhcpd_event ndp_event = {{.fd = -1}, handle_solicit};
50 static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
53 // Filter ICMPv6 messages of type neighbor soliciation
54 static struct sock_filter bpf[] = {
55 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, offsetof(struct ip6_hdr, ip6_nxt)),
56 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, IPPROTO_ICMPV6, 0, 3),
57 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, sizeof(struct ip6_hdr) +
58 offsetof(struct icmp6_hdr, icmp6_type)),
59 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ND_NEIGHBOR_SOLICIT, 0, 1),
60 BPF_STMT(BPF_RET | BPF_K, 0xffffffff),
61 BPF_STMT(BPF_RET | BPF_K, 0),
63 static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
66 // Initialize NDP-proxy
69 // Setup netlink socket
70 if ((rtnl_event.uloop.fd = odhcpd_open_rtnl()) < 0)
73 // Receive netlink neighbor and ip-address events
74 uint32_t group = RTNLGRP_IPV6_IFADDR;
75 setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
76 NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
77 group = RTNLGRP_IPV6_ROUTE;
78 setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
79 NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
81 // Synthesize initial address events
86 {sizeof(req2), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
88 {.ifa_family = AF_INET6}
90 send(rtnl_event.uloop.fd, &req2, sizeof(req2), MSG_DONTWAIT);
91 odhcpd_register(&rtnl_event);
94 // Create socket for intercepting NDP
95 int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
96 htons(ETH_P_ALL)); // ETH_P_ALL for ingress + egress
98 syslog(LOG_ERR, "Unable to open packet socket: %s",
103 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
104 &bpf_prog, sizeof(bpf_prog))) {
105 syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
109 ndp_event.uloop.fd = sock;
110 odhcpd_register(&ndp_event);
112 // Open ICMPv6 socket
113 ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
116 setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
118 // This is required by RFC 4861
120 setsockopt(ping_socket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
121 setsockopt(ping_socket, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
123 // Filter all packages, we only want to send
124 struct icmp6_filter filt;
125 ICMP6_FILTER_SETBLOCKALL(&filt);
126 setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
129 // Netlink socket, continued...
130 group = RTNLGRP_NEIGH;
131 setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
133 // Synthesize initial neighbor events
138 {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
140 {.ndm_family = AF_INET6}
142 send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
148 int setup_ndp_interface(struct interface *iface, bool enable)
150 struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
151 setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
153 struct ndp_neighbor *c, *n;
154 list_for_each_entry_safe(c, n, &neighbors, head)
155 if (c->iface == iface && (c->timeout == 0 || iface->ndp != RELAYD_RELAY || !enable))
156 modify_neighbor(&c->addr, c->iface, false);
158 if (enable && iface->ndp == RELAYD_RELAY) {
159 setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
161 if (iface->static_ndp_len) {
162 char *entry = alloca(iface->static_ndp_len), *saveptr;
164 syslog(LOG_ERR, "Alloca failed for static NDP list");
167 memcpy(entry, iface->static_ndp, iface->static_ndp_len);
169 for (entry = strtok_r(entry, " ", &saveptr); entry; entry = strtok_r(NULL, " ", &saveptr)) {
170 struct ndp_neighbor *n = malloc(sizeof(*n));
172 syslog(LOG_ERR, "Malloc failed for static NDP-prefix %s", entry);
179 char ipbuf[INET6_ADDRSTRLEN];
180 if (sscanf(entry, "%45s/%hhu", ipbuf, &n->len) < 2
181 || n->len > 128 || inet_pton(AF_INET6, ipbuf, &n->addr) != 1) {
182 syslog(LOG_ERR, "Invalid static NDP-prefix %s", entry);
186 list_add(&n->head, &neighbors);
195 // Send an ICMP-ECHO. This is less for actually pinging but for the
196 // neighbor cache to be kept up-to-date.
197 static ssize_t ping6(struct in6_addr *addr,
198 const struct interface *iface)
200 struct sockaddr_in6 dest = {AF_INET6, 0, 0, *addr, 0};
201 struct icmp6_hdr echo = {.icmp6_type = ICMP6_ECHO_REQUEST};
202 struct iovec iov = {&echo, sizeof(echo)};
204 // Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
205 setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
206 iface->ifname, sizeof(iface->ifname));
207 return odhcpd_send(ping_socket, &dest, &iov, 1, iface);
211 // Handle solicitations
212 static void handle_solicit(void *addr, void *data, size_t len,
213 struct interface *iface)
215 struct ip6_hdr *ip6 = data;
216 struct nd_neighbor_solicit *req = (struct nd_neighbor_solicit*)&ip6[1];
217 struct sockaddr_ll *ll = addr;
219 // Solicitation is for duplicate address detection
220 bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src);
222 // Don't forward any non-DAD solicitation for external ifaces
223 // TODO: check if we should even forward DADs for them
224 if (iface->external && !ns_is_dad)
227 if (len < sizeof(*ip6) + sizeof(*req))
228 return; // Invalid reqicitation
230 if (IN6_IS_ADDR_LINKLOCAL(&req->nd_ns_target) ||
231 IN6_IS_ADDR_LOOPBACK(&req->nd_ns_target) ||
232 IN6_IS_ADDR_MULTICAST(&req->nd_ns_target))
233 return; // Invalid target
235 char ipbuf[INET6_ADDRSTRLEN];
236 inet_ntop(AF_INET6, &req->nd_ns_target, ipbuf, sizeof(ipbuf));
237 syslog(LOG_DEBUG, "Got a NS for %s", ipbuf);
240 odhcpd_get_mac(iface, mac);
241 if (!memcmp(ll->sll_addr, mac, sizeof(mac)) &&
242 ll->sll_pkttype != PACKET_OUTGOING)
243 return; // Looped back
245 time_t now = time(NULL);
247 struct ndp_neighbor *n = find_neighbor(&req->nd_ns_target, false);
248 if (n && (n->iface || abs(n->timeout - now) < 5)) {
249 syslog(LOG_DEBUG, "%s is on %s", ipbuf,
250 (n->iface) ? n->iface->ifname : "<pending>");
251 if (!n->iface || n->iface == iface)
254 // Found on other interface, answer with advertisement
256 struct nd_neighbor_advert body;
257 struct nd_opt_hdr opt_ll_hdr;
261 .nd_na_hdr = {ND_NEIGHBOR_ADVERT,
263 .nd_na_target = req->nd_ns_target,
265 .opt_ll_hdr = {ND_OPT_TARGET_LINKADDR, 1},
268 memcpy(advert.mac, mac, sizeof(advert.mac));
269 advert.body.nd_na_flags_reserved = ND_NA_FLAG_ROUTER |
270 ND_NA_FLAG_SOLICITED;
272 struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
273 if (!ns_is_dad) // If not DAD, then unicast to source
274 dest.sin6_addr = ip6->ip6_src;
276 // Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
277 setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
278 iface->ifname, sizeof(iface->ifname));
279 struct iovec iov = {&advert, sizeof(advert)};
280 odhcpd_send(ping_socket, &dest, &iov, 1, iface);
282 // Send echo to all other interfaces to see where target is on
283 // This will trigger neighbor discovery which is what we want.
284 // We will observe the neighbor cache to see results.
288 list_for_each_entry(c, &interfaces, head)
289 if (iface->ndp == RELAYD_RELAY && iface != c &&
290 (!ns_is_dad || !c->external == false))
291 sent += ping6(&req->nd_ns_target, c);
293 if (sent > 0) // Sent a ping, add pending neighbor entry
294 modify_neighbor(&req->nd_ns_target, NULL, true);
299 void odhcpd_setup_route(const struct in6_addr *addr, int prefixlen,
300 const struct interface *iface, const struct in6_addr *gw, bool add)
305 struct rtattr rta_dst;
306 struct in6_addr dst_addr;
307 struct rtattr rta_oif;
309 struct rtattr rta_table;
311 struct rtattr rta_gw;
314 {sizeof(req), 0, NLM_F_REQUEST, ++rtnl_seqid, 0},
315 {AF_INET6, prefixlen, 0, 0, 0, 0, 0, 0, 0},
316 {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_DST},
318 {sizeof(struct rtattr) + sizeof(uint32_t), RTA_OIF},
320 {sizeof(struct rtattr) + sizeof(uint32_t), RTA_TABLE},
322 {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_GATEWAY},
330 req.nh.nlmsg_type = RTM_NEWROUTE;
331 req.nh.nlmsg_flags |= (NLM_F_CREATE | NLM_F_REPLACE);
332 req.rtm.rtm_protocol = RTPROT_BOOT;
333 req.rtm.rtm_scope = (gw) ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK;
334 req.rtm.rtm_type = RTN_UNICAST;
336 req.nh.nlmsg_type = RTM_DELROUTE;
337 req.rtm.rtm_scope = RT_SCOPE_NOWHERE;
340 size_t reqlen = (gw) ? sizeof(req) : offsetof(struct req, rta_gw);
341 send(rtnl_event.uloop.fd, &req, reqlen, MSG_DONTWAIT);
344 // Use rtnetlink to modify kernel routes
345 static void setup_route(struct in6_addr *addr, struct interface *iface,
348 char namebuf[INET6_ADDRSTRLEN];
349 inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
350 syslog(LOG_NOTICE, "%s about %s on %s", (add) ? "Learned" : "Forgot",
351 namebuf, (iface) ? iface->ifname : "<pending>");
353 if (!iface || !iface->learn_routes)
356 odhcpd_setup_route(addr, 128, iface, NULL, add);
359 static void free_neighbor(struct ndp_neighbor *n)
361 setup_route(&n->addr, n->iface, false);
368 static bool match_neighbor(struct ndp_neighbor *n, struct in6_addr *addr)
371 return ntohl(n->addr.s6_addr32[0]) >> (32 - n->len) ==
372 ntohl(addr->s6_addr32[0]) >> (32 - n->len);
374 if (n->addr.s6_addr32[0] != addr->s6_addr32[0])
378 return ntohl(n->addr.s6_addr32[1]) >> (64 - n->len) ==
379 ntohl(addr->s6_addr32[1]) >> (64 - n->len);
381 if (n->addr.s6_addr32[1] != addr->s6_addr32[1])
385 return ntohl(n->addr.s6_addr32[2]) >> (96 - n->len) ==
386 ntohl(addr->s6_addr32[2]) >> (96 - n->len);
388 if (n->addr.s6_addr32[2] != addr->s6_addr32[2])
391 return ntohl(n->addr.s6_addr32[3]) >> (128 - n->len) ==
392 ntohl(addr->s6_addr32[3]) >> (128 - n->len);
396 static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict)
398 time_t now = time(NULL);
399 struct ndp_neighbor *n, *e;
400 list_for_each_entry_safe(n, e, &neighbors, head) {
401 if ((!strict && match_neighbor(n, addr)) ||
402 (n->len == 128 && IN6_ARE_ADDR_EQUAL(&n->addr, addr)))
405 if (!n->iface && abs(n->timeout - now) >= 5)
412 // Modified our own neighbor-entries
413 static void modify_neighbor(struct in6_addr *addr,
414 struct interface *iface, bool add)
416 if (!addr || (void*)addr == (void*)iface)
419 struct ndp_neighbor *n = find_neighbor(addr, true);
420 if (!add) { // Delete action
421 if (n && (!n->iface || n->iface == iface))
423 } else if (!n) { // No entry yet, add one if possible
424 if (neighbor_count >= NDP_MAX_NEIGHBORS ||
425 !(n = malloc(sizeof(*n))))
433 list_add(&n->head, &neighbors);
435 setup_route(addr, n->iface, add);
436 } else if (n->iface == iface) {
439 } else if (iface && (!n->iface ||
440 (!iface->external && n->iface->external))) {
441 setup_route(addr, n->iface, false);
443 setup_route(addr, n->iface, add);
445 // TODO: In case a host switches interfaces we might want
446 // to set its old neighbor entry to NUD_STALE and ping it
447 // on the old interface to confirm if the MACs match.
451 // Handler for neighbor cache entries from the kernel. This is our source
452 // to learn and unlearn hosts on interfaces.
453 static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
454 _unused struct interface *iface)
456 for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len);
457 nh = NLMSG_NEXT(nh, len)) {
458 struct rtmsg *rtm = NLMSG_DATA(nh);
459 if ((nh->nlmsg_type == RTM_NEWROUTE ||
460 nh->nlmsg_type == RTM_DELROUTE) &&
461 rtm->rtm_dst_len == 0)
462 raise(SIGUSR1); // Inform about a change in default route
464 struct ndmsg *ndm = NLMSG_DATA(nh);
465 struct ifaddrmsg *ifa = NLMSG_DATA(nh);
466 if (nh->nlmsg_type != RTM_NEWNEIGH
467 && nh->nlmsg_type != RTM_DELNEIGH
468 && nh->nlmsg_type != RTM_NEWADDR
469 && nh->nlmsg_type != RTM_DELADDR)
470 continue; // Unrelated message type
471 bool is_addr = (nh->nlmsg_type == RTM_NEWADDR
472 || nh->nlmsg_type == RTM_DELADDR);
474 // Family and ifindex are on the same offset for NEIGH and ADDR
475 if (NLMSG_PAYLOAD(nh, 0) < sizeof(*ndm)
476 || ndm->ndm_family != AF_INET6)
480 struct interface *iface;
481 if (!(iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex)))
485 size_t rta_offset = (is_addr) ? sizeof(*ifa) : sizeof(*ndm);
486 uint16_t atype = (is_addr) ? IFA_ADDRESS : NDA_DST;
487 ssize_t alen = NLMSG_PAYLOAD(nh, rta_offset);
488 struct in6_addr *addr = NULL;
490 for (struct rtattr *rta = (void*)(((uint8_t*)ndm) + rta_offset);
491 RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen))
492 if (rta->rta_type == atype &&
493 RTA_PAYLOAD(rta) >= sizeof(*addr))
494 addr = RTA_DATA(rta);
496 // Address not specified or unrelated
497 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
498 IN6_IS_ADDR_MULTICAST(addr))
504 add = (nh->nlmsg_type == RTM_NEWADDR);
506 add = (nh->nlmsg_type == RTM_NEWNEIGH && (ndm->ndm_state &
507 (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE
508 | NUD_PERMANENT | NUD_NOARP)));
510 if (iface->ndp == RELAYD_RELAY)
511 modify_neighbor(addr, iface, add);
513 if (is_addr && iface->ra == RELAYD_SERVER)
514 raise(SIGUSR1); // Inform about a change in addresses
516 if (is_addr && iface->dhcpv6 == RELAYD_SERVER)
517 iface->ia_reconf = true;
519 if (iface->ndp == RELAYD_RELAY && is_addr && iface->master) {
520 // Replay address changes on all slave interfaces
521 nh->nlmsg_flags = NLM_F_REQUEST;
523 if (nh->nlmsg_type == RTM_NEWADDR)
524 nh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
527 list_for_each_entry(c, &interfaces, head) {
528 if (c->ndp == RELAYD_RELAY && !c->master) {
529 ifa->ifa_index = c->ifindex;
530 send(rtnl_event.uloop.fd, nh, nh->nlmsg_len, MSG_DONTWAIT);
535 /* TODO: See if this is required for optimal operation
536 // Keep neighbor entries alive so we don't loose routes
538 if (add && (ndm->ndm_state & NUD_STALE))