dhcpv6-ia: simplify logic to write statefile and dhcpv6 logging
[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 "dhcpv6.h"
37 #include "odhcpd.h"
38
39 struct event_socket {
40         struct odhcpd_event ev;
41         struct nl_sock *sock;
42         int sock_bufsize;
43 };
44
45 static void handle_solicit(void *addr, void *data, size_t len,
46                 struct interface *iface, void *dest);
47 static void handle_rtnl_event(struct odhcpd_event *ev);
48 static int cb_rtnl_valid(struct nl_msg *msg, void *arg);
49 static void catch_rtnl_err(struct odhcpd_event *e, int error);
50
51 static int addr6_dump_rqs = 0;
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_addr6_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 void ndp_handle_addr6_dump(void)
172 {
173         if (!addr6_dump_rqs)
174                 return;
175
176         dump_addr6_table();
177         addr6_dump_rqs = 0;
178 }
179
180 inline void ndp_rqs_addr6_dump(void)
181 {
182         addr6_dump_rqs++;
183 }
184
185 int setup_ndp_interface(struct interface *iface, bool enable)
186 {
187         int ret = 0, procfd;
188         bool dump_neigh = false;
189         char procbuf[64];
190
191         snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
192         procfd = open(procbuf, O_WRONLY);
193
194         if (procfd < 0) {
195                 ret = -1;
196                 goto out;
197         }
198
199         if (iface->ndp_event.uloop.fd > 0) {
200                 uloop_fd_delete(&iface->ndp_event.uloop);
201                 close(iface->ndp_event.uloop.fd);
202                 iface->ndp_event.uloop.fd = -1;
203
204                 if (!enable || iface->ndp != RELAYD_RELAY)
205                         if (write(procfd, "0\n", 2) < 0) {}
206
207                 dump_neigh = true;
208         }
209
210         if (enable && iface->ndp == RELAYD_RELAY) {
211                 if (write(procfd, "1\n", 2) < 0) {}
212
213                 int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
214                 if (sock < 0) {
215                         syslog(LOG_ERR, "Unable to open packet socket: %s",
216                                         strerror(errno));
217                         ret = -1;
218                         goto out;
219                 }
220
221 #ifdef PACKET_RECV_TYPE
222                 int pktt = 1 << PACKET_MULTICAST;
223                 setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
224 #endif
225
226                 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
227                                 &bpf_prog, sizeof(bpf_prog))) {
228                         syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
229                         ret = -1;
230                         goto out;
231                 }
232
233                 struct sockaddr_ll ll = {
234                         .sll_family = AF_PACKET,
235                         .sll_ifindex = iface->ifindex,
236                         .sll_protocol = htons(ETH_P_IPV6),
237                         .sll_hatype = 0,
238                         .sll_pkttype = 0,
239                         .sll_halen = 0,
240                         .sll_addr = {0},
241                 };
242                 bind(sock, (struct sockaddr*)&ll, sizeof(ll));
243
244                 struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
245                 setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
246
247                 iface->ndp_event.uloop.fd = sock;
248                 iface->ndp_event.handle_dgram = handle_solicit;
249                 odhcpd_register(&iface->ndp_event);
250
251                 // If we already were enabled dump is unnecessary, if not do dump
252                 if (!dump_neigh)
253                         dump_neigh_table(false);
254                 else
255                         dump_neigh = false;
256
257                 ndp_rqs_addr6_dump();
258         }
259
260         if (dump_neigh)
261                 dump_neigh_table(true);
262
263 out:
264         if (procfd >= 0)
265                 close(procfd);
266
267         return ret;
268 }
269
270
271 // Send an ICMP-ECHO. This is less for actually pinging but for the
272 // neighbor cache to be kept up-to-date.
273 static void ping6(struct in6_addr *addr,
274                 const struct interface *iface)
275 {
276         struct sockaddr_in6 dest = { .sin6_family = AF_INET6, .sin6_addr = *addr, .sin6_scope_id = iface->ifindex, };
277         struct icmp6_hdr echo = { .icmp6_type = ICMP6_ECHO_REQUEST };
278         struct iovec iov = { .iov_base = &echo, .iov_len = sizeof(echo) };
279         char ipbuf[INET6_ADDRSTRLEN];
280
281         inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
282         syslog(LOG_NOTICE, "Pinging for %s%%%s", ipbuf, iface->ifname);
283
284         odhcpd_setup_route(addr, 128, iface, NULL, 128, true);
285         odhcpd_send(ping_socket, &dest, &iov, 1, iface);
286         odhcpd_setup_route(addr, 128, iface, NULL, 128, false);
287 }
288
289 // Handle solicitations
290 static void handle_solicit(void *addr, void *data, size_t len,
291                 struct interface *iface, _unused void *dest)
292 {
293         struct ip6_hdr *ip6 = data;
294         struct nd_neighbor_solicit *req = (struct nd_neighbor_solicit*)&ip6[1];
295         struct sockaddr_ll *ll = addr;
296         char ipbuf[INET6_ADDRSTRLEN];
297         uint8_t mac[6];
298
299         // Solicitation is for duplicate address detection
300         bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src);
301
302         // Don't process solicit messages on non relay interfaces
303         // Don't forward any non-DAD solicitation for external ifaces
304         // TODO: check if we should even forward DADs for them
305         if (iface->ndp != RELAYD_RELAY || (iface->external && !ns_is_dad))
306                 return;
307
308         if (len < sizeof(*ip6) + sizeof(*req))
309                 return; // Invalid reqicitation
310
311         if (IN6_IS_ADDR_LINKLOCAL(&req->nd_ns_target) ||
312                         IN6_IS_ADDR_LOOPBACK(&req->nd_ns_target) ||
313                         IN6_IS_ADDR_MULTICAST(&req->nd_ns_target))
314                 return; // Invalid target
315
316         inet_ntop(AF_INET6, &req->nd_ns_target, ipbuf, sizeof(ipbuf));
317         syslog(LOG_DEBUG, "Got a NS for %s%%%s", ipbuf, iface->ifname);
318
319         odhcpd_get_mac(iface, mac);
320         if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
321                 return; // Looped back
322
323         struct interface *c;
324         list_for_each_entry(c, &interfaces, head)
325                 if (iface != c && c->ndp == RELAYD_RELAY &&
326                                 (ns_is_dad || !c->external))
327                         ping6(&req->nd_ns_target, c);
328 }
329
330 // Use rtnetlink to modify kernel routes
331 static void setup_route(struct in6_addr *addr, struct interface *iface, bool add)
332 {
333         char ipbuf[INET6_ADDRSTRLEN];
334
335         inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
336         syslog(LOG_NOTICE, "%s about %s%%%s",
337                         (add) ? "Learned" : "Forgot", ipbuf, iface->ifname);
338
339         if (iface->learn_routes)
340                 odhcpd_setup_route(addr, 128, iface, NULL, 1024, add);
341 }
342
343 // compare prefixes
344 static int prefixcmp(const void *va, const void *vb)
345 {
346         const struct odhcpd_ipaddr *a = va, *b = vb;
347         uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr) ? 1 : a->preferred;
348         uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr) ? 1 : b->preferred;
349         return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
350 }
351
352 // Check address update
353 static void check_addr_updates(struct interface *iface)
354 {
355         struct odhcpd_ipaddr addr[RELAYD_MAX_ADDRS] = {{IN6ADDR_ANY_INIT, 0, 0, 0, 0}};
356         time_t now = odhcpd_time();
357         ssize_t len = odhcpd_get_interface_addresses(iface->ifindex, addr, ARRAY_SIZE(addr));
358
359         if (len < 0)
360                 return;
361
362         qsort(addr, len, sizeof(*addr), prefixcmp);
363
364         for (int i = 0; i < len; ++i) {
365                 if (addr[i].preferred < UINT32_MAX - now)
366                         addr[i].preferred += now;
367
368                 if (addr[i].valid < UINT32_MAX - now)
369                         addr[i].valid += now;
370         }
371
372         bool change = len != (ssize_t)iface->ia_addr_len;
373         for (ssize_t i = 0; !change && i < len; ++i)
374                 if (!IN6_ARE_ADDR_EQUAL(&addr[i].addr, &iface->ia_addr[i].addr) ||
375                                 (addr[i].preferred > 0) != (iface->ia_addr[i].preferred > 0) ||
376                                 addr[i].valid < iface->ia_addr[i].valid ||
377                                 addr[i].preferred < iface->ia_addr[i].preferred)
378                         change = true;
379
380         if (change)
381                 dhcpv6_ia_preupdate(iface);
382
383         memcpy(iface->ia_addr, addr, len * sizeof(*addr));
384         iface->ia_addr_len = len;
385
386         if (change)
387                 dhcpv6_ia_postupdate(iface, now);
388
389         if (change) {
390                 syslog(LOG_INFO, "Raising SIGUSR1 due to address change on %s", iface->ifname);
391                 raise(SIGUSR1);
392         }
393 }
394
395 static void setup_addr_for_relaying(struct in6_addr *addr, struct interface *iface, bool add)
396 {
397         struct interface *c;
398         char ipbuf[INET6_ADDRSTRLEN];
399
400         inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
401
402         list_for_each_entry(c, &interfaces, head) {
403                 if (iface == c || (c->ndp != RELAYD_RELAY && !add))
404                         continue;
405
406                 add = (c->ndp == RELAYD_RELAY ? add : false);
407
408                 if (odhcpd_setup_proxy_neigh(addr, c, add))
409                         syslog(LOG_DEBUG, "Failed to %s proxy neighbour entry %s%%%s",
410                                 add ? "add" : "delete", ipbuf, iface->ifname);
411                 else
412                         syslog(LOG_DEBUG, "%s proxy neighbour entry %s%%%s",
413                                 add ? "Added" : "Deleted", ipbuf, iface->ifname);
414         }
415 }
416
417 static void setup_ping6(struct in6_addr *addr, struct interface *iface)
418 {
419         struct interface *c;
420
421         list_for_each_entry(c, &interfaces, head) {
422                 if (iface == c || c->ndp != RELAYD_RELAY ||
423                                 c->external == true)
424                         continue;
425
426                 ping6(addr, c);
427         }
428 }
429
430 static struct in6_addr last_solicited;
431
432 static void handle_rtnl_event(struct odhcpd_event *e)
433 {
434         struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
435
436         nl_recvmsgs_default(ev_sock->sock);
437 }
438
439
440 // Handler for neighbor cache entries from the kernel. This is our source
441 // to learn and unlearn hosts on interfaces.
442 static int cb_rtnl_valid(struct nl_msg *msg, _unused void *arg)
443 {
444         struct nlmsghdr *hdr = nlmsg_hdr(msg);
445         struct in6_addr *addr = NULL;
446         struct interface *iface = NULL;
447         bool add = false;
448         char ipbuf[INET6_ADDRSTRLEN];
449
450         switch (hdr->nlmsg_type) {
451         case RTM_NEWROUTE:
452         case RTM_DELROUTE: {
453                 struct rtmsg *rtm = nlmsg_data(hdr);
454
455                 if (!nlmsg_valid_hdr(hdr, sizeof(*rtm)) ||
456                                 rtm->rtm_family != AF_INET6)
457                         return NL_SKIP;
458
459                 if (rtm->rtm_dst_len == 0) {
460                         syslog(LOG_INFO, "Raising SIGUSR1 due to default route change");
461                         raise(SIGUSR1);
462                 }
463                 return NL_OK;
464         }
465
466         case RTM_NEWADDR:
467                 add = true;
468         case RTM_DELADDR: {
469                 struct ifaddrmsg *ifa = nlmsg_data(hdr);
470                 struct nlattr *nla[__IFA_MAX];
471
472                 if (!nlmsg_valid_hdr(hdr, sizeof(*ifa)) ||
473                                 ifa->ifa_family != AF_INET6)
474                         return NL_SKIP;
475
476                 iface = odhcpd_get_interface_by_index(ifa->ifa_index);
477                 if (!iface)
478                         return NL_SKIP;
479
480                 nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
481                 if (!nla[IFA_ADDRESS])
482                         return NL_SKIP;
483
484                 addr = nla_data(nla[IFA_ADDRESS]);
485                 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
486                                 IN6_IS_ADDR_MULTICAST(addr))
487                         return NL_SKIP;
488
489                 inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
490                 syslog(LOG_DEBUG, "Netlink %s %s%%%s", true ? "newaddr" : "deladdr",
491                         ipbuf, iface->ifname);
492
493                 check_addr_updates(iface);
494
495                 if (iface->ndp != RELAYD_RELAY)
496                         break;
497
498                 /* handle the relay logic below */
499                 setup_addr_for_relaying(addr, iface, add);
500
501                 if (!add)
502                         dump_neigh_table(false);
503                 break;
504         }
505
506         case RTM_NEWNEIGH:
507                 add = true;
508         case RTM_DELNEIGH: {
509                 struct ndmsg *ndm = nlmsg_data(hdr);
510                 struct nlattr *nla[__NDA_MAX];
511
512                 if (!nlmsg_valid_hdr(hdr, sizeof(*ndm)) ||
513                                 ndm->ndm_family != AF_INET6)
514                         return NL_SKIP;
515
516                 iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex);
517                 if (!iface || iface->ndp != RELAYD_RELAY)
518                         return (iface ? NL_OK : NL_SKIP);
519
520                 nlmsg_parse(hdr, sizeof(*ndm), nla, __NDA_MAX - 1, NULL);
521                 if (!nla[NDA_DST])
522                         return NL_SKIP;
523
524                 addr = nla_data(nla[NDA_DST]);
525                 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
526                                 IN6_IS_ADDR_MULTICAST(addr))
527                         return NL_SKIP;
528
529                 inet_ntop(AF_INET6, addr, ipbuf, sizeof(ipbuf));
530                 syslog(LOG_DEBUG, "Netlink %s %s%%%s", true ? "newneigh" : "delneigh",
531                         ipbuf, iface->ifname);
532
533                 if (ndm->ndm_flags & NTF_PROXY) {
534                         /* Dump and flush proxy entries */
535                         if (hdr->nlmsg_type == RTM_NEWNEIGH) {
536                                 odhcpd_setup_proxy_neigh(addr, iface, false);
537                                 setup_route(addr, iface, false);
538                                 dump_neigh_table(false);
539                         }
540
541                         return NL_OK;
542                 }
543
544                 if (add && !(ndm->ndm_state &
545                                 (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE |
546                                  NUD_PERMANENT | NUD_NOARP))) {
547                         if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
548                                 last_solicited = *addr;
549                                 setup_ping6(addr, iface);
550                         }
551
552                         return NL_OK;
553                 }
554
555                 setup_addr_for_relaying(addr, iface, add);
556                 setup_route(addr, iface, add);
557
558                 if (!add)
559                         dump_neigh_table(false);
560                 break;
561         }
562
563         default:
564                 return NL_SKIP;
565         }
566
567         return NL_OK;
568 }
569
570 static void catch_rtnl_err(struct odhcpd_event *e, int error)
571 {
572         struct event_socket *ev_sock = container_of(e, struct event_socket, ev);
573
574         if (error != ENOBUFS)
575                 goto err;
576
577         /* Double netlink event buffer size */
578         ev_sock->sock_bufsize *= 2;
579
580         if (nl_socket_set_buffer_size(ev_sock->sock, ev_sock->sock_bufsize, 0))
581                 goto err;
582
583         dump_addr6_table();
584         return;
585
586 err:
587         odhcpd_deregister(e);
588 }