427547dad9995899d54ac341bd0c36cc32bb017c
[project/odhcpd.git] / src / ndp.c
1 /**
2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.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 */
14
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <signal.h>
18 #include <errno.h>
19
20 #include <fcntl.h>
21 #include <unistd.h>
22 #include <arpa/inet.h>
23 #include <sys/socket.h>
24 #include <net/ethernet.h>
25 #include <netinet/ip6.h>
26 #include <netinet/icmp6.h>
27 #include <netpacket/packet.h>
28
29 #include <linux/rtnetlink.h>
30 #include <linux/filter.h>
31
32 #include <netlink/msg.h>
33 #include <netlink/socket.h>
34 #include <netlink/attr.h>
35
36 #include "router.h"
37 #include "dhcpv6.h"
38 #include "ndp.h"
39
40 struct event_socket {
41 struct odhcpd_event ev;
42 struct nl_sock *sock;
43 int sock_bufsize;
44 };
45
46 static void handle_solicit(void *addr, void *data, size_t len,
47 struct interface *iface, void *dest);
48 static void handle_rtnl_event(struct odhcpd_event *ev);
49 static int cb_rtnl_valid(struct nl_msg *msg, void *arg);
50 static void catch_rtnl_err(struct odhcpd_event *e, int error);
51
52 static int ping_socket = -1;
53 static struct event_socket rtnl_event = {
54 .ev = {
55 .uloop = {.fd = - 1, },
56 .handle_dgram = NULL,
57 .handle_error = catch_rtnl_err,
58 .recv_msgs = handle_rtnl_event,
59 },
60 .sock = NULL,
61 .sock_bufsize = 133120,
62 };
63
64 // Filter ICMPv6 messages of type neighbor soliciation
65 static struct sock_filter bpf[] = {
66 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, offsetof(struct ip6_hdr, ip6_nxt)),
67 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, IPPROTO_ICMPV6, 0, 3),
68 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, sizeof(struct ip6_hdr) +
69 offsetof(struct icmp6_hdr, icmp6_type)),
70 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ND_NEIGHBOR_SOLICIT, 0, 1),
71 BPF_STMT(BPF_RET | BPF_K, 0xffffffff),
72 BPF_STMT(BPF_RET | BPF_K, 0),
73 };
74 static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
75
76
77 // Initialize NDP-proxy
78 int init_ndp(void)
79 {
80 int val = 2;
81
82 rtnl_event.sock = odhcpd_create_nl_socket(NETLINK_ROUTE);
83 if (!rtnl_event.sock)
84 goto err;
85
86 rtnl_event.ev.uloop.fd = nl_socket_get_fd(rtnl_event.sock);
87
88 if (nl_socket_set_buffer_size(rtnl_event.sock, rtnl_event.sock_bufsize, 0))
89 goto err;
90
91 nl_socket_disable_seq_check(rtnl_event.sock);
92
93 nl_socket_modify_cb(rtnl_event.sock, NL_CB_VALID, NL_CB_CUSTOM,
94 cb_rtnl_valid, NULL);
95
96 // Receive IPv6 address, IPv6 routes and neighbor events
97 if (nl_socket_add_memberships(rtnl_event.sock, RTNLGRP_IPV6_IFADDR,
98 RTNLGRP_IPV6_ROUTE, RTNLGRP_NEIGH, 0))
99 goto err;
100
101 odhcpd_register(&rtnl_event.ev);
102
103 // Open ICMPv6 socket
104 ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
105 if (ping_socket < 0) {
106 syslog(LOG_ERR, "Unable to open raw socket: %s", strerror(errno));
107 return -1;
108 }
109
110 setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
111
112 // This is required by RFC 4861
113 val = 255;
114 setsockopt(ping_socket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
115 setsockopt(ping_socket, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
116
117 // Filter all packages, we only want to send
118 struct icmp6_filter filt;
119 ICMP6_FILTER_SETBLOCKALL(&filt);
120 setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
121
122 return 0;
123
124 err:
125 if (rtnl_event.sock) {
126 nl_socket_free(rtnl_event.sock);
127 rtnl_event.sock = NULL;
128 rtnl_event.ev.uloop.fd = -1;
129 }
130
131 return -1;
132 }
133
134 static void dump_neigh_table(const bool proxy)
135 {
136 struct nl_msg *msg;
137 struct ndmsg ndm = {
138 .ndm_family = AF_INET6,
139 .ndm_flags = proxy ? NTF_PROXY : 0,
140 };
141
142 msg = nlmsg_alloc_simple(RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP);
143 if (!msg)
144 return;
145
146 nlmsg_append(msg, &ndm, sizeof(ndm), 0);
147
148 nl_send_auto_complete(rtnl_event.sock, msg);
149
150 nlmsg_free(msg);
151 }
152
153 static void dump_addr_table(void)
154 {
155 struct nl_msg *msg;
156 struct ifaddrmsg ifa = {
157 .ifa_family = AF_INET6,
158 };
159
160 msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
161 if (!msg)
162 return;
163
164 nlmsg_append(msg, &ifa, sizeof(ifa), 0);
165
166 nl_send_auto_complete(rtnl_event.sock, msg);
167
168 nlmsg_free(msg);
169 }
170
171 int setup_ndp_interface(struct interface *iface, bool enable)
172 {
173 int ret = 0, procfd;
174 bool dump_neigh = false;
175 char procbuf[64];
176
177 snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
178 procfd = open(procbuf, O_WRONLY);
179
180 if (procfd < 0) {
181 ret = -1;
182 goto out;
183 }
184
185 if (iface->ndp_event.uloop.fd > 0) {
186 uloop_fd_delete(&iface->ndp_event.uloop);
187 close(iface->ndp_event.uloop.fd);
188 iface->ndp_event.uloop.fd = -1;
189
190 if (!enable || iface->ndp != RELAYD_RELAY)
191 if (write(procfd, "0\n", 2) < 0) {}
192
193 dump_neigh = true;
194 }
195
196 if (enable && (iface->ra == RELAYD_SERVER ||
197 iface->dhcpv6 == RELAYD_SERVER || iface->ndp == RELAYD_RELAY))
198 dump_addr_table();
199
200 if (enable && iface->ndp == RELAYD_RELAY) {
201 if (write(procfd, "1\n", 2) < 0) {}
202
203 int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
204 if (sock < 0) {
205 syslog(LOG_ERR, "Unable to open packet socket: %s",
206 strerror(errno));
207 ret = -1;
208 goto out;
209 }
210
211 #ifdef PACKET_RECV_TYPE
212 int pktt = 1 << PACKET_MULTICAST;
213 setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
214 #endif
215
216 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
217 &bpf_prog, sizeof(bpf_prog))) {
218 syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
219 ret = -1;
220 goto out;
221 }
222
223 struct sockaddr_ll ll = {
224 .sll_family = AF_PACKET,
225 .sll_ifindex = iface->ifindex,
226 .sll_protocol = htons(ETH_P_IPV6),
227 .sll_hatype = 0,
228 .sll_pkttype = 0,
229 .sll_halen = 0,
230 .sll_addr = {0},
231 };
232 bind(sock, (struct sockaddr*)&ll, sizeof(ll));
233
234 struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
235 setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
236
237 iface->ndp_event.uloop.fd = sock;
238 iface->ndp_event.handle_dgram = handle_solicit;
239 odhcpd_register(&iface->ndp_event);
240
241 // If we already were enabled dump is unnecessary, if not do dump
242 if (!dump_neigh)
243 dump_neigh_table(false);
244 else
245 dump_neigh = false;
246 }
247
248 if (dump_neigh)
249 dump_neigh_table(true);
250
251 out:
252 if (procfd >= 0)
253 close(procfd);
254
255 return ret;
256 }
257
258
259 // Send an ICMP-ECHO. This is less for actually pinging but for the
260 // neighbor cache to be kept up-to-date.
261 static void ping6(struct in6_addr *addr,
262 const struct interface *iface)
263 {
264 struct sockaddr_in6 dest = { .sin6_family = AF_INET6, .sin6_addr = *addr, .sin6_scope_id = iface->ifindex, };
265 struct icmp6_hdr echo = { .icmp6_type = ICMP6_ECHO_REQUEST };
266 struct iovec iov = { .iov_base = &echo, .iov_len = sizeof(echo) };
267
268 odhcpd_setup_route(addr, 128, iface, NULL, 128, true);
269 odhcpd_send(ping_socket, &dest, &iov, 1, iface);
270 odhcpd_setup_route(addr, 128, iface, NULL, 128, false);
271 }
272
273
274 // Handle solicitations
275 static void handle_solicit(void *addr, void *data, size_t len,
276 struct interface *iface, _unused void *dest)
277 {
278 struct ip6_hdr *ip6 = data;
279 struct nd_neighbor_solicit *req = (struct nd_neighbor_solicit*)&ip6[1];
280 struct sockaddr_ll *ll = addr;
281
282 // Solicitation is for duplicate address detection
283 bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src);
284
285 // Don't process solicit messages on non relay interfaces
286 // Don't forward any non-DAD solicitation for external ifaces
287 // TODO: check if we should even forward DADs for them
288 if (iface->ndp != RELAYD_RELAY || (iface->external && !ns_is_dad))
289 return;
290
291 if (len < sizeof(*ip6) + sizeof(*req))
292 return; // Invalid reqicitation
293
294 if (IN6_IS_ADDR_LINKLOCAL(&req->nd_ns_target) ||
295 IN6_IS_ADDR_LOOPBACK(&req->nd_ns_target) ||
296 IN6_IS_ADDR_MULTICAST(&req->nd_ns_target))
297 return; // Invalid target
298
299 char ipbuf[INET6_ADDRSTRLEN];
300 inet_ntop(AF_INET6, &req->nd_ns_target, ipbuf, sizeof(ipbuf));
301 syslog(LOG_DEBUG, "Got a NS for %s", ipbuf);
302
303 uint8_t mac[6];
304 odhcpd_get_mac(iface, mac);
305 if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
306 return; // Looped back
307
308 struct interface *c;
309 list_for_each_entry(c, &interfaces, head)
310 if (iface != c && c->ndp == RELAYD_RELAY &&
311 (ns_is_dad || !c->external))
312 ping6(&req->nd_ns_target, c);
313 }
314
315 // Use rtnetlink to modify kernel routes
316 static void setup_route(struct in6_addr *addr, struct interface *iface, bool add)
317 {
318 char namebuf[INET6_ADDRSTRLEN];
319 inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
320 syslog(LOG_NOTICE, "%s about %s on %s",
321 (add) ? "Learned" : "Forgot", namebuf, iface->ifname);
322
323 if (iface->learn_routes)
324 odhcpd_setup_route(addr, 128, iface, NULL, 1024, add);
325 }
326
327 // compare prefixes
328 static int prefixcmp(const void *va, const void *vb)
329 {
330 const struct odhcpd_ipaddr *a = va, *b = vb;
331 uint32_t a_pref = ((a->addr.s6_addr[0] & 0xfe) != 0xfc) ? a->preferred : 1;
332 uint32_t b_pref = ((b->addr.s6_addr[0] & 0xfe) != 0xfc) ? b->preferred : 1;
333 return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
334 }
335
336 // Check address update
337 static void check_addr_updates(struct interface *iface)
338 {
339 struct odhcpd_ipaddr addr[RELAYD_MAX_ADDRS] = {{IN6ADDR_ANY_INIT, 0, 0, 0, 0}};
340 time_t now = odhcpd_time();
341 ssize_t len = odhcpd_get_interface_addresses(iface->ifindex, addr, ARRAY_SIZE(addr));
342
343 if (len < 0)
344 return;
345
346 qsort(addr, len, sizeof(*addr), prefixcmp);
347
348 for (int i = 0; i < len; ++i) {
349 addr[i].addr.s6_addr32[3] = 0;
350
351 if (addr[i].preferred < UINT32_MAX - now)
352 addr[i].preferred += now;
353
354 if (addr[i].valid < UINT32_MAX - now)
355 addr[i].valid += now;
356 }
357
358 bool change = len != (ssize_t)iface->ia_addr_len;
359 for (ssize_t i = 0; !change && i < len; ++i)
360 if (!IN6_ARE_ADDR_EQUAL(&addr[i].addr, &iface->ia_addr[i].addr) ||
361 (addr[i].preferred > 0) != (iface->ia_addr[i].preferred > 0) ||
362 addr[i].valid < iface->ia_addr[i].valid ||
363 addr[i].preferred < iface->ia_addr[i].preferred)
364 change = true;
365
366 if (change)
367 dhcpv6_ia_preupdate(iface);
368
369 memcpy(iface->ia_addr, addr, len * sizeof(*addr));
370 iface->ia_addr_len = len;
371
372 if (change)
373 dhcpv6_ia_postupdate(iface, now);
374
375 if (change) {
376 syslog(LOG_INFO, "Raising SIGUSR1 due to address change on %s", iface->ifname);
377 raise(SIGUSR1);
378 }
379 }
380
381 void setup_addr_for_relaying(struct in6_addr *addr, struct interface *iface, bool add)
382 {
383 struct interface *c;
384
385 list_for_each_entry(c, &interfaces, head) {
386 if (iface == c || (c->ndp != RELAYD_RELAY && !add))
387 continue;
388
389 odhcpd_setup_proxy_neigh(addr, c, c->ndp == RELAYD_RELAY ? add : false);
390 }
391 }
392
393 void setup_ping6(struct in6_addr *addr, struct interface *iface)
394 {
395 struct interface *c;
396
397 list_for_each_entry(c, &interfaces, head) {
398 if (iface == c || c->ndp != RELAYD_RELAY ||
399 c->external == true)
400 continue;
401
402 ping6(addr, c);
403 }
404 }
405
406 static struct in6_addr last_solicited;
407
408 static void handle_rtnl_event(struct odhcpd_event *e)
409 {
410 struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
411
412 nl_recvmsgs_default(ev_sock->sock);
413 }
414
415
416 // Handler for neighbor cache entries from the kernel. This is our source
417 // to learn and unlearn hosts on interfaces.
418 static int cb_rtnl_valid(struct nl_msg *msg, _unused void *arg)
419 {
420 struct nlmsghdr *hdr = nlmsg_hdr(msg);
421 struct in6_addr *addr = NULL;
422 struct interface *iface = NULL;
423 bool add = false;
424
425 switch (hdr->nlmsg_type) {
426 case RTM_NEWROUTE:
427 case RTM_DELROUTE: {
428 struct rtmsg *rtm = nlmsg_data(hdr);
429
430 if (!nlmsg_valid_hdr(hdr, sizeof(*rtm)) ||
431 rtm->rtm_family != AF_INET6)
432 return NL_SKIP;
433
434 if (rtm->rtm_dst_len == 0) {
435 syslog(LOG_INFO, "Raising SIGUSR1 due to default route change");
436 raise(SIGUSR1);
437 }
438 return NL_OK;
439 }
440
441 case RTM_NEWADDR:
442 add = true;
443 case RTM_DELADDR: {
444 struct ifaddrmsg *ifa = nlmsg_data(hdr);
445 struct nlattr *nla[__IFA_MAX];
446
447 if (!nlmsg_valid_hdr(hdr, sizeof(*ifa)) ||
448 ifa->ifa_family != AF_INET6)
449 return NL_SKIP;
450
451 iface = odhcpd_get_interface_by_index(ifa->ifa_index);
452 if (!iface)
453 return NL_SKIP;
454
455 nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
456 if (!nla[IFA_ADDRESS])
457 return NL_SKIP;
458
459 addr = nla_data(nla[IFA_ADDRESS]);
460 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
461 IN6_IS_ADDR_MULTICAST(addr))
462 return NL_SKIP;
463
464 check_addr_updates(iface);
465
466 if (iface->ndp != RELAYD_RELAY)
467 break;
468
469 /* handle the relay logic below */
470 setup_addr_for_relaying(addr, iface, add);
471
472 if (!add)
473 dump_neigh_table(false);
474 break;
475 }
476
477 case RTM_NEWNEIGH:
478 add = true;
479 case RTM_DELNEIGH: {
480 struct ndmsg *ndm = nlmsg_data(hdr);
481 struct nlattr *nla[__NDA_MAX];
482
483 if (!nlmsg_valid_hdr(hdr, sizeof(*ndm)) ||
484 ndm->ndm_family != AF_INET6)
485 return NL_SKIP;
486
487 iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex);
488 if (!iface || iface->ndp != RELAYD_RELAY)
489 return (iface ? NL_OK : NL_SKIP);
490
491 nlmsg_parse(hdr, sizeof(*ndm), nla, __NDA_MAX - 1, NULL);
492 if (!nla[NDA_DST])
493 return NL_SKIP;
494
495 addr = nla_data(nla[NDA_DST]);
496 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
497 IN6_IS_ADDR_MULTICAST(addr))
498 return NL_SKIP;
499
500 if (ndm->ndm_flags & NTF_PROXY) {
501 /* Dump and flush proxy entries */
502 if (hdr->nlmsg_type == RTM_NEWNEIGH) {
503 odhcpd_setup_proxy_neigh(addr, iface, false);
504 setup_route(addr, iface, false);
505 dump_neigh_table(false);
506 }
507
508 return NL_OK;
509 }
510
511 if (add && !(ndm->ndm_state &
512 (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE |
513 NUD_PERMANENT | NUD_NOARP))) {
514 if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
515 last_solicited = *addr;
516 setup_ping6(addr, iface);
517 }
518
519 return NL_OK;
520 }
521
522 setup_addr_for_relaying(addr, iface, add);
523 setup_route(addr, iface, add);
524
525 if (!add)
526 dump_neigh_table(false);
527 break;
528 }
529
530 default:
531 return NL_SKIP;
532 }
533
534 return NL_OK;
535 }
536
537 static void catch_rtnl_err(struct odhcpd_event *e, int error)
538 {
539 struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
540
541 if (error != ENOBUFS)
542 goto err;
543
544 /* Double netlink event buffer size */
545 ev_sock->sock_bufsize *= 2;
546
547 if (nl_socket_set_buffer_size(ev_sock->sock, ev_sock->sock_bufsize, 0))
548 goto err;
549
550 dump_addr_table();
551 return;
552
553 err:
554 odhcpd_deregister(e);
555 }