Fix wrong address pool being advertised
[project/odhcpd.git] / src / router.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 <errno.h>
16 #include <fcntl.h>
17 #include <signal.h>
18 #include <resolv.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <unistd.h>
22 #include <stdbool.h>
23 #include <net/route.h>
24
25 #include "router.h"
26 #include "odhcpd.h"
27
28
29 static void forward_router_solicitation(const struct interface *iface);
30 static void forward_router_advertisement(uint8_t *data, size_t len);
31
32 static void handle_icmpv6(void *addr, void *data, size_t len,
33 struct interface *iface);
34 static void send_router_advert(struct uloop_timeout *event);
35 static void sigusr1_refresh(int signal);
36
37 static struct odhcpd_event router_event = {{.fd = -1}, handle_icmpv6};
38
39 static FILE *fp_route = NULL;
40
41
42 int init_router(void)
43 {
44 // Open ICMPv6 socket
45 int sock = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
46 if (sock < 0 && errno != EAFNOSUPPORT) {
47 syslog(LOG_ERR, "Failed to open RAW-socket: %s", strerror(errno));
48 return -1;
49 }
50
51 // Let the kernel compute our checksums
52 int val = 2;
53 setsockopt(sock, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
54
55 // This is required by RFC 4861
56 val = 255;
57 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
58 setsockopt(sock, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
59
60 // We need to know the source interface
61 val = 1;
62 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
63 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &val, sizeof(val));
64
65 // Don't loop back
66 val = 0;
67 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
68
69 // Filter ICMPv6 package types
70 struct icmp6_filter filt;
71 ICMP6_FILTER_SETBLOCKALL(&filt);
72 ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filt);
73 ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filt);
74 setsockopt(sock, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
75
76 // Register socket
77 router_event.uloop.fd = sock;
78 odhcpd_register(&router_event);
79
80 if (!(fp_route = fopen("/proc/net/ipv6_route", "r")))
81 syslog(LOG_ERR, "Failed to open routing table: %s",
82 strerror(errno));
83
84 signal(SIGUSR1, sigusr1_refresh);
85 return 0;
86 }
87
88
89 int setup_router_interface(struct interface *iface, bool enable)
90 {
91 struct ipv6_mreq all_nodes = {ALL_IPV6_NODES, iface->ifindex};
92 struct ipv6_mreq all_routers = {ALL_IPV6_ROUTERS, iface->ifindex};
93
94 uloop_timeout_cancel(&iface->timer_rs);
95 iface->timer_rs.cb = NULL;
96
97 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
98 &all_nodes, sizeof(all_nodes));
99 setsockopt(router_event.uloop.fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,
100 &all_routers, sizeof(all_routers));
101
102 if (!enable) {
103 if (iface->ra)
104 send_router_advert(&iface->timer_rs);
105 } else {
106 void *mreq = &all_routers;
107
108 if (iface->ra == RELAYD_RELAY && iface->master) {
109 mreq = &all_nodes;
110 forward_router_solicitation(iface);
111 } else if (iface->ra == RELAYD_SERVER && !iface->master) {
112 iface->timer_rs.cb = send_router_advert;
113 send_router_advert(&iface->timer_rs);
114 }
115
116 if (iface->ra == RELAYD_RELAY || (iface->ra == RELAYD_SERVER && !iface->master))
117 setsockopt(router_event.uloop.fd, IPPROTO_IPV6,
118 IPV6_ADD_MEMBERSHIP, mreq, sizeof(all_nodes));
119 }
120 return 0;
121 }
122
123
124 // Signal handler to resend all RDs
125 static void sigusr1_refresh(_unused int signal)
126 {
127 struct interface *iface;
128 list_for_each_entry(iface, &interfaces, head)
129 if (iface->ra == RELAYD_SERVER && !iface->master)
130 uloop_timeout_set(&iface->timer_rs, 1000);
131 }
132
133 static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size_t len)
134 {
135 struct icmp6_hdr *hdr = (struct icmp6_hdr *)data;
136 struct icmpv6_opt *opt, *end = (struct icmpv6_opt*)&data[len];
137
138 /* Hoplimit is already checked in odhcpd_receive_packets */
139 if (len < sizeof(*hdr) || hdr->icmp6_code)
140 return false;
141
142 switch (hdr->icmp6_type) {
143 case ND_ROUTER_ADVERT:
144 if (!IN6_IS_ADDR_LINKLOCAL(&source->sin6_addr))
145 return false;
146
147 opt = (struct icmpv6_opt *)((struct nd_router_advert *)data + 1);
148 break;
149
150 case ND_ROUTER_SOLICIT:
151 opt = (struct icmpv6_opt *)((struct nd_router_solicit *)data + 1);
152 break;
153
154 default:
155 return false;
156 }
157
158 icmpv6_for_each_option(opt, opt, end)
159 if (opt->type == ND_OPT_SOURCE_LINKADDR &&
160 IN6_IS_ADDR_UNSPECIFIED(&source->sin6_addr) &&
161 hdr->icmp6_type == ND_ROUTER_SOLICIT)
162 return false;
163
164 // Check all options parsed successfully
165 return opt == end;
166 }
167
168 // Event handler for incoming ICMPv6 packets
169 static void handle_icmpv6(void *addr, void *data, size_t len,
170 struct interface *iface)
171 {
172 struct icmp6_hdr *hdr = data;
173
174 if (!router_icmpv6_valid(addr, data, len))
175 return;
176
177 if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
178 if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
179 send_router_advert(&iface->timer_rs);
180 } else if (iface->ra == RELAYD_RELAY) { // Relay mode
181 if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
182 forward_router_advertisement(data, len);
183 else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
184 forward_router_solicitation(odhcpd_get_master_interface());
185 }
186 }
187
188
189 // Detect whether a default route exists, also find the source prefixes
190 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
191 {
192 rewind(fp_route);
193
194 char line[512], ifname[16];
195 bool found_default = false;
196 struct odhcpd_ipaddr p = {IN6ADDR_ANY_INIT, 0, 0, false, 0, 0, 0};
197 while (fgets(line, sizeof(line), fp_route)) {
198 uint32_t rflags;
199 if (sscanf(line, "00000000000000000000000000000000 00 "
200 "%*s %*s %*s %*s %*s %*s %*s %15s", ifname) &&
201 strcmp(ifname, "lo")) {
202 found_default = true;
203 } else if (sscanf(line, "%8" SCNx32 "%8" SCNx32 "%*8" SCNx32 "%*8" SCNx32 " %hhx %*s "
204 "%*s 00000000000000000000000000000000 %*s %*s %*s %" SCNx32 " lo",
205 &p.addr.s6_addr32[0], &p.addr.s6_addr32[1], &p.prefix, &rflags) &&
206 p.prefix > 0 && (rflags & RTF_NONEXTHOP) && (rflags & RTF_REJECT)) {
207 // Find source prefixes by scanning through unreachable-routes
208 p.addr.s6_addr32[0] = htonl(p.addr.s6_addr32[0]);
209 p.addr.s6_addr32[1] = htonl(p.addr.s6_addr32[1]);
210
211 for (ssize_t i = 0; i < len; ++i) {
212 if (n[i].prefix <= 64 && n[i].prefix >= p.prefix &&
213 !odhcpd_bmemcmp(&p.addr, &n[i].addr, p.prefix)) {
214 n[i].dprefix = p.prefix;
215 break;
216 }
217 }
218
219 }
220 }
221
222 return found_default;
223 }
224
225
226 // Router Advert server mode
227 static void send_router_advert(struct uloop_timeout *event)
228 {
229 struct interface *iface =
230 container_of(event, struct interface, timer_rs);
231
232 int mtu = odhcpd_get_interface_mtu(iface->ifname);
233 if (mtu < 0)
234 mtu = 1500;
235
236 struct {
237 struct nd_router_advert h;
238 struct icmpv6_opt lladdr;
239 struct nd_opt_mtu mtu;
240 struct nd_opt_prefix_info prefix[RELAYD_MAX_PREFIXES];
241 } adv = {
242 .h = {{.icmp6_type = ND_ROUTER_ADVERT, .icmp6_code = 0}, 0, 0},
243 .lladdr = {ND_OPT_SOURCE_LINKADDR, 1, {0}},
244 .mtu = {ND_OPT_MTU, 1, 0, htonl(mtu)},
245 };
246
247 if (iface->dhcpv6)
248 adv.h.nd_ra_flags_reserved = ND_RA_FLAG_OTHER;
249
250 if (iface->managed >= RELAYD_MANAGED_MFLAG)
251 adv.h.nd_ra_flags_reserved |= ND_RA_FLAG_MANAGED;
252
253 if (iface->route_preference < 0)
254 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_LOW;
255 else if (iface->route_preference > 0)
256 adv.h.nd_ra_flags_reserved |= ND_RA_PREF_HIGH;
257 odhcpd_get_mac(iface, adv.lladdr.data);
258
259 // If not currently shutting down
260 struct odhcpd_ipaddr addrs[RELAYD_MAX_PREFIXES];
261 ssize_t ipcnt = 0;
262 uint64_t maxpreferred = 0;
263
264 // If not shutdown
265 if (event->cb) {
266 ipcnt = odhcpd_get_interface_addresses(iface->ifindex,
267 addrs, ARRAY_SIZE(addrs));
268
269 // Check default route
270 if (parse_routes(addrs, ipcnt) || iface->default_router > 1)
271 adv.h.nd_ra_router_lifetime =
272 htons(3 * MaxRtrAdvInterval);
273 }
274
275 // Construct Prefix Information options
276 bool have_public = false;
277 size_t cnt = 0;
278
279 struct in6_addr *dns_addr = NULL;
280 uint32_t dns_time = 0;
281 size_t dns_cnt = 1;
282
283 for (ssize_t i = 0; i < ipcnt; ++i) {
284 struct odhcpd_ipaddr *addr = &addrs[i];
285 if (addr->prefix > 96 || addr->has_class)
286 continue; // Address not suitable
287
288 if (addr->preferred > MaxPreferredTime)
289 addr->preferred = MaxPreferredTime;
290
291 if (addr->valid > MaxValidTime)
292 addr->valid = MaxValidTime;
293
294 struct nd_opt_prefix_info *p = NULL;
295 for (size_t i = 0; i < cnt; ++i) {
296 if (addr->prefix == adv.prefix[i].nd_opt_pi_prefix_len &&
297 !odhcpd_bmemcmp(&adv.prefix[i].nd_opt_pi_prefix,
298 &addr->addr, addr->prefix))
299 p = &adv.prefix[i];
300 }
301
302 if (!p) {
303 if (cnt >= ARRAY_SIZE(adv.prefix))
304 break;
305
306 p = &adv.prefix[cnt++];
307 }
308
309 if ((addr->addr.s6_addr[0] & 0xfe) != 0xfc && addr->preferred > 0) {
310 have_public = true;
311
312 if (maxpreferred < 1000 * addr->preferred)
313 maxpreferred = 1000 * addr->preferred;
314 }
315
316 odhcpd_bmemcpy(&p->nd_opt_pi_prefix, &addr->addr, addr->prefix);
317 p->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
318 p->nd_opt_pi_len = 4;
319 p->nd_opt_pi_prefix_len = (addr->prefix < 64) ? 64 : addr->prefix;
320 p->nd_opt_pi_flags_reserved = 0;
321 if (!iface->ra_not_onlink)
322 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_ONLINK;
323 if (iface->managed < RELAYD_MANAGED_NO_AFLAG && addr->prefix <= 64)
324 p->nd_opt_pi_flags_reserved |= ND_OPT_PI_FLAG_AUTO;
325 p->nd_opt_pi_valid_time = htonl(addr->valid);
326 p->nd_opt_pi_preferred_time = htonl(addr->preferred);
327
328 if (addr->preferred > dns_time) {
329 dns_time = addr->preferred;
330 dns_addr = &addr->addr;
331 }
332 }
333
334 if (!have_public && !iface->default_router && adv.h.nd_ra_router_lifetime) {
335 syslog(LOG_WARNING, "A default route is present but there is no public prefix "
336 "on %s thus we don't announce a default route!", iface->ifname);
337 adv.h.nd_ra_router_lifetime = 0;
338 }
339
340 // DNS Recursive DNS
341 if (iface->dns_cnt > 0) {
342 dns_addr = iface->dns;
343 dns_cnt = iface->dns_cnt;
344 dns_time = 2 * MaxRtrAdvInterval;
345 }
346
347 if (!dns_addr)
348 dns_cnt = 0;
349
350 struct {
351 uint8_t type;
352 uint8_t len;
353 uint8_t pad;
354 uint8_t pad2;
355 uint32_t lifetime;
356 } dns = {ND_OPT_RECURSIVE_DNS, (1 + (2 * dns_cnt)), 0, 0, htonl(dns_time)};
357
358
359
360 // DNS Search options
361 uint8_t search_buf[256], *search_domain = iface->search;
362 size_t search_len = iface->search_len, search_padded = 0;
363
364 if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
365 int len = dn_comp(_res.dnsrch[0], search_buf,
366 sizeof(search_buf), NULL, NULL);
367 if (len > 0) {
368 search_domain = search_buf;
369 search_len = len;
370 }
371 }
372
373 if (search_len > 0)
374 search_padded = ((search_len + 7) & (~7)) + 8;
375
376 struct {
377 uint8_t type;
378 uint8_t len;
379 uint8_t pad;
380 uint8_t pad2;
381 uint32_t lifetime;
382 uint8_t name[];
383 } *search = alloca(sizeof(*search) + search_padded);
384
385 if (!search) {
386 syslog(LOG_ERR, "Alloca failed for dns search on interface %s", iface->ifname);
387 return;
388 }
389 search->type = ND_OPT_DNS_SEARCH;
390 search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
391 search->pad = 0;
392 search->pad2 = 0;
393 search->lifetime = htonl(2 * MaxRtrAdvInterval);;
394 memcpy(search->name, search_domain, search_len);
395 memset(&search->name[search_len], 0, search_padded - search_len);
396
397
398 size_t routes_cnt = 0;
399 struct {
400 uint8_t type;
401 uint8_t len;
402 uint8_t prefix;
403 uint8_t flags;
404 uint32_t lifetime;
405 uint32_t addr[4];
406 } routes[RELAYD_MAX_PREFIXES];
407
408 for (ssize_t i = 0; i < ipcnt; ++i) {
409 struct odhcpd_ipaddr *addr = &addrs[i];
410 if (addr->dprefix > 64 || addr->dprefix == 0) {
411 continue; // Address not suitable
412 } else if (addr->dprefix > 32) {
413 addr->addr.s6_addr32[1] &= htonl(~((1U << (64 - addr->dprefix)) - 1));
414 } else if (addr->dprefix <= 32) {
415 addr->addr.s6_addr32[0] &= htonl(~((1U << (32 - addr->dprefix)) - 1));
416 addr->addr.s6_addr32[1] = 0;
417 }
418
419 routes[routes_cnt].type = ND_OPT_ROUTE_INFO;
420 routes[routes_cnt].len = sizeof(*routes) / 8;
421 routes[routes_cnt].prefix = addr->dprefix;
422 routes[routes_cnt].flags = 0;
423 if (iface->route_preference < 0)
424 routes[routes_cnt].flags |= ND_RA_PREF_LOW;
425 else if (iface->route_preference > 0)
426 routes[routes_cnt].flags |= ND_RA_PREF_HIGH;
427 routes[routes_cnt].lifetime = htonl(addr->valid);
428 routes[routes_cnt].addr[0] = addr->addr.s6_addr32[0];
429 routes[routes_cnt].addr[1] = addr->addr.s6_addr32[1];
430 routes[routes_cnt].addr[2] = addr->addr.s6_addr32[2];
431 routes[routes_cnt].addr[3] = addr->addr.s6_addr32[3];
432
433 ++routes_cnt;
434 }
435
436
437 struct iovec iov[] = {{&adv, (uint8_t*)&adv.prefix[cnt] - (uint8_t*)&adv},
438 {&routes, routes_cnt * sizeof(*routes)},
439 {&dns, (dns_cnt) ? sizeof(dns) : 0},
440 {dns_addr, dns_cnt * sizeof(*dns_addr)},
441 {search, search->len * 8}};
442 struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
443 odhcpd_send(router_event.uloop.fd,
444 &all_nodes, iov, ARRAY_SIZE(iov), iface);
445
446 // Rearm timer if not shut down
447 if (event->cb) {
448 uint32_t maxinterval = MaxRtrAdvInterval * 1000;
449 uint32_t mininterval = MinRtrAdvInterval * 1000;
450
451 if (maxpreferred > 0 && maxinterval > maxpreferred / 2) {
452 maxinterval = maxpreferred / 2;
453 if (maxinterval < 4000)
454 maxinterval = 4000;
455
456 if (maxinterval >= 9000)
457 mininterval = maxinterval / 3;
458 else
459 mininterval = (maxinterval * 3) / 4;
460 }
461
462 int msecs;
463 odhcpd_urandom(&msecs, sizeof(msecs));
464 msecs = (labs(msecs) % (maxinterval - mininterval)) + mininterval;
465 uloop_timeout_set(&iface->timer_rs, msecs);
466 }
467 }
468
469
470 // Forward router solicitation
471 static void forward_router_solicitation(const struct interface *iface)
472 {
473 if (!iface)
474 return;
475
476 struct icmp6_hdr rs = {ND_ROUTER_SOLICIT, 0, 0, {{0}}};
477 struct iovec iov = {&rs, sizeof(rs)};
478 struct sockaddr_in6 all_routers =
479 {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, iface->ifindex};
480
481 syslog(LOG_NOTICE, "Sending RS to %s", iface->ifname);
482 odhcpd_send(router_event.uloop.fd, &all_routers, &iov, 1, iface);
483 }
484
485
486 // Handler for incoming router solicitations on slave interfaces
487 static void forward_router_advertisement(uint8_t *data, size_t len)
488 {
489 struct nd_router_advert *adv = (struct nd_router_advert *)data;
490
491 // Rewrite options
492 uint8_t *end = data + len;
493 uint8_t *mac_ptr = NULL;
494 struct in6_addr *dns_ptr = NULL;
495 size_t dns_count = 0;
496
497 struct icmpv6_opt *opt;
498 icmpv6_for_each_option(opt, &adv[1], end) {
499 if (opt->type == ND_OPT_SOURCE_LINKADDR) {
500 // Store address of source MAC-address
501 mac_ptr = opt->data;
502 } else if (opt->type == ND_OPT_RECURSIVE_DNS && opt->len > 1) {
503 // Check if we have to rewrite DNS
504 dns_ptr = (struct in6_addr*)&opt->data[6];
505 dns_count = (opt->len - 1) / 2;
506 }
507 }
508
509 syslog(LOG_NOTICE, "Got a RA");
510
511 // Indicate a proxy, however we don't follow the rest of RFC 4389 yet
512 adv->nd_ra_flags_reserved |= ND_RA_FLAG_PROXY;
513
514 // Forward advertisement to all slave interfaces
515 struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
516 struct iovec iov = {data, len};
517
518 struct odhcpd_ipaddr addr;
519 struct interface *iface;
520 list_for_each_entry(iface, &interfaces, head) {
521 if (iface->ra != RELAYD_RELAY || iface->master)
522 continue;
523
524 // Fixup source hardware address option
525 if (mac_ptr)
526 odhcpd_get_mac(iface, mac_ptr);
527
528 // If we have to rewrite DNS entries
529 if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
530 const struct in6_addr *rewrite = iface->dns;
531 size_t rewrite_cnt = iface->dns_cnt;
532
533 if (rewrite_cnt == 0) {
534 if (odhcpd_get_interface_addresses(iface->ifindex, &addr, 1) < 1)
535 continue; // Unable to comply
536
537 rewrite = &addr.addr;
538 rewrite_cnt = 1;
539 }
540
541 // Copy over any other addresses
542 for (size_t i = 0; i < dns_count; ++i) {
543 size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
544 dns_ptr[i] = rewrite[j];
545 }
546 }
547
548 odhcpd_send(router_event.uloop.fd, &all_nodes, &iov, 1, iface);
549 }
550 }