odhcpd: use proper struct msghdr initializers to fix build error on musl
[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 #include "router.h"
32 #include "ndp.h"
33
34
35
36 static void handle_solicit(void *addr, void *data, size_t len,
37                 struct interface *iface, void *dest);
38 static void handle_rtnetlink(void *addr, void *data, size_t len,
39                 struct interface *iface, void *dest);
40 static ssize_t ping6(struct in6_addr *addr,
41                 const struct interface *iface);
42
43 static uint32_t rtnl_seqid = 0;
44 static int ping_socket = -1;
45 static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
46
47
48 // Filter ICMPv6 messages of type neighbor soliciation
49 static struct sock_filter bpf[] = {
50         BPF_STMT(BPF_LD | BPF_B | BPF_ABS, offsetof(struct ip6_hdr, ip6_nxt)),
51         BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, IPPROTO_ICMPV6, 0, 3),
52         BPF_STMT(BPF_LD | BPF_B | BPF_ABS, sizeof(struct ip6_hdr) +
53                         offsetof(struct icmp6_hdr, icmp6_type)),
54         BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, ND_NEIGHBOR_SOLICIT, 0, 1),
55         BPF_STMT(BPF_RET | BPF_K, 0xffffffff),
56         BPF_STMT(BPF_RET | BPF_K, 0),
57 };
58 static const struct sock_fprog bpf_prog = {sizeof(bpf) / sizeof(*bpf), bpf};
59
60
61 // Initialize NDP-proxy
62 int init_ndp(void)
63 {
64         // Setup netlink socket
65         if ((rtnl_event.uloop.fd = odhcpd_open_rtnl()) < 0)
66                 return -1;
67
68         // Receive netlink neighbor and ip-address events
69         uint32_t group = RTNLGRP_IPV6_IFADDR;
70         setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
71                         NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
72         group = RTNLGRP_IPV6_ROUTE;
73         setsockopt(rtnl_event.uloop.fd, SOL_NETLINK,
74                         NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
75
76         odhcpd_register(&rtnl_event);
77
78         // Open ICMPv6 socket
79         ping_socket = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC, IPPROTO_ICMPV6);
80         if (ping_socket < 0) {
81                 syslog(LOG_ERR, "Unable to open raw socket: %s", strerror(errno));
82                         return -1;
83         }
84
85         int val = 2;
86         setsockopt(ping_socket, IPPROTO_RAW, IPV6_CHECKSUM, &val, sizeof(val));
87
88         // This is required by RFC 4861
89         val = 255;
90         setsockopt(ping_socket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
91         setsockopt(ping_socket, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &val, sizeof(val));
92
93         // Filter all packages, we only want to send
94         struct icmp6_filter filt;
95         ICMP6_FILTER_SETBLOCKALL(&filt);
96         setsockopt(ping_socket, IPPROTO_ICMPV6, ICMP6_FILTER, &filt, sizeof(filt));
97
98
99         // Netlink socket, continued...
100         group = RTNLGRP_NEIGH;
101         setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
102
103         return 0;
104 }
105
106
107 static void dump_neigh_table(bool proxy)
108 {
109         struct {
110                 struct nlmsghdr nh;
111                 struct ndmsg ndm;
112         } req = {
113                 {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
114                                 ++rtnl_seqid, 0},
115                 {.ndm_family = AF_INET6, .ndm_flags = (proxy) ? NTF_PROXY : 0}
116         };
117         send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
118         odhcpd_process(&rtnl_event);
119 }
120
121
122 int setup_ndp_interface(struct interface *iface, bool enable)
123 {
124         char procbuf[64];
125         snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
126         int procfd = open(procbuf, O_WRONLY);
127         bool dump_neigh = false;
128
129         if (iface->ndp_event.uloop.fd > 0) {
130                 uloop_fd_delete(&iface->ndp_event.uloop);
131                 close(iface->ndp_event.uloop.fd);
132                 iface->ndp_event.uloop.fd = -1;
133
134                 if (!enable || iface->ndp != RELAYD_RELAY)
135                         write(procfd, "0\n", 2);
136
137                 dump_neigh = true;
138         }
139
140         if (enable && (iface->ra == RELAYD_SERVER ||
141                         iface->dhcpv6 == RELAYD_SERVER || iface->ndp == RELAYD_RELAY)) {
142                 // Synthesize initial address events
143                 struct {
144                         struct nlmsghdr nh;
145                         struct ifaddrmsg ifa;
146                 } req2 = {
147                         {sizeof(req2), RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP,
148                                         ++rtnl_seqid, 0},
149                         {.ifa_family = AF_INET6, .ifa_index = iface->ifindex}
150                 };
151                 send(rtnl_event.uloop.fd, &req2, sizeof(req2), MSG_DONTWAIT);
152         }
153
154         if (enable && iface->ndp == RELAYD_RELAY) {
155                 write(procfd, "1\n", 2);
156                 close(procfd);
157
158                 int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
159                 if (sock < 0) {
160                         syslog(LOG_ERR, "Unable to open packet socket: %s",
161                                         strerror(errno));
162                         return -1;
163                 }
164
165 #ifdef PACKET_RECV_TYPE
166                 int pktt = 1 << PACKET_MULTICAST;
167                 setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
168 #endif
169
170                 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
171                                 &bpf_prog, sizeof(bpf_prog))) {
172                         syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
173                         return -1;
174                 }
175
176                 struct sockaddr_ll ll = {
177                         .sll_family = AF_PACKET,
178                         .sll_ifindex = iface->ifindex,
179                         .sll_protocol = htons(ETH_P_IPV6),
180                         .sll_hatype = 0,
181                         .sll_pkttype = 0,
182                         .sll_halen = 0,
183                         .sll_addr = {0},
184                 };
185                 bind(sock, (struct sockaddr*)&ll, sizeof(ll));
186
187                 struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
188                 setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
189
190                 iface->ndp_event.uloop.fd = sock;
191                 iface->ndp_event.handle_dgram = handle_solicit;
192                 odhcpd_register(&iface->ndp_event);
193
194                 // If we already were enabled dump is unnecessary, if not do dump
195                 if (!dump_neigh)
196                         dump_neigh_table(false);
197                 else
198                         dump_neigh = false;
199         } else {
200                 close(procfd);
201         }
202
203         if (dump_neigh)
204                 dump_neigh_table(true);
205
206         return 0;
207 }
208
209
210 // Send an ICMP-ECHO. This is less for actually pinging but for the
211 // neighbor cache to be kept up-to-date.
212 static ssize_t ping6(struct in6_addr *addr,
213                 const struct interface *iface)
214 {
215         struct sockaddr_in6 dest = {AF_INET6, 0, 0, *addr, 0};
216         struct icmp6_hdr echo = {.icmp6_type = ICMP6_ECHO_REQUEST};
217         struct iovec iov = {&echo, sizeof(echo)};
218
219         // Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
220         setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
221                         iface->ifname, sizeof(iface->ifname));
222         return odhcpd_send(ping_socket, &dest, &iov, 1, iface);
223 }
224
225
226 // Handle solicitations
227 static void handle_solicit(void *addr, void *data, size_t len,
228                 struct interface *iface, _unused void *dest)
229 {
230         struct ip6_hdr *ip6 = data;
231         struct nd_neighbor_solicit *req = (struct nd_neighbor_solicit*)&ip6[1];
232         struct sockaddr_ll *ll = addr;
233
234         // Solicitation is for duplicate address detection
235         bool ns_is_dad = IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src);
236
237         // Don't forward any non-DAD solicitation for external ifaces
238         // TODO: check if we should even forward DADs for them
239         if (iface->external && !ns_is_dad)
240                 return;
241
242         if (len < sizeof(*ip6) + sizeof(*req))
243                 return; // Invalid reqicitation
244
245         if (IN6_IS_ADDR_LINKLOCAL(&req->nd_ns_target) ||
246                         IN6_IS_ADDR_LOOPBACK(&req->nd_ns_target) ||
247                         IN6_IS_ADDR_MULTICAST(&req->nd_ns_target))
248                 return; // Invalid target
249
250         char ipbuf[INET6_ADDRSTRLEN];
251         inet_ntop(AF_INET6, &req->nd_ns_target, ipbuf, sizeof(ipbuf));
252         syslog(LOG_DEBUG, "Got a NS for %s", ipbuf);
253
254         uint8_t mac[6];
255         odhcpd_get_mac(iface, mac);
256         if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
257                 return; // Looped back
258
259         struct interface *c;
260         list_for_each_entry(c, &interfaces, head)
261                 if (iface->ndp == RELAYD_RELAY && iface != c &&
262                                 (ns_is_dad || !c->external))
263                         ping6(&req->nd_ns_target, c);
264 }
265
266
267 void odhcpd_setup_route(const struct in6_addr *addr, int prefixlen,
268                 const struct interface *iface, const struct in6_addr *gw, bool add)
269 {
270         struct req {
271                 struct nlmsghdr nh;
272                 struct rtmsg rtm;
273                 struct rtattr rta_dst;
274                 struct in6_addr dst_addr;
275                 struct rtattr rta_oif;
276                 uint32_t ifindex;
277                 struct rtattr rta_table;
278                 uint32_t table;
279                 struct rtattr rta_gw;
280                 struct in6_addr gw;
281         } req = {
282                 {sizeof(req), 0, NLM_F_REQUEST, ++rtnl_seqid, 0},
283                 {AF_INET6, prefixlen, 0, 0, 0, 0, 0, 0, 0},
284                 {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_DST},
285                 *addr,
286                 {sizeof(struct rtattr) + sizeof(uint32_t), RTA_OIF},
287                 iface->ifindex,
288                 {sizeof(struct rtattr) + sizeof(uint32_t), RTA_TABLE},
289                 RT_TABLE_MAIN,
290                 {sizeof(struct rtattr) + sizeof(struct in6_addr), RTA_GATEWAY},
291                 IN6ADDR_ANY_INIT,
292         };
293
294         if (gw)
295                 req.gw = *gw;
296
297         if (add) {
298                 req.nh.nlmsg_type = RTM_NEWROUTE;
299                 req.nh.nlmsg_flags |= (NLM_F_CREATE | NLM_F_REPLACE);
300                 req.rtm.rtm_protocol = RTPROT_STATIC;
301                 req.rtm.rtm_scope = (gw) ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK;
302                 req.rtm.rtm_type = RTN_UNICAST;
303         } else {
304                 req.nh.nlmsg_type = RTM_DELROUTE;
305                 req.rtm.rtm_scope = RT_SCOPE_NOWHERE;
306         }
307
308         req.nh.nlmsg_len = (gw) ? sizeof(req) : offsetof(struct req, rta_gw);
309         send(rtnl_event.uloop.fd, &req, req.nh.nlmsg_len, MSG_DONTWAIT);
310 }
311
312 // Use rtnetlink to modify kernel routes
313 static void setup_route(struct in6_addr *addr, struct interface *iface, bool add)
314 {
315         char namebuf[INET6_ADDRSTRLEN];
316         inet_ntop(AF_INET6, addr, namebuf, sizeof(namebuf));
317         syslog(LOG_NOTICE, "%s about %s on %s",
318                         (add) ? "Learned" : "Forgot", namebuf, iface->ifname);
319
320         if (iface->learn_routes)
321                 odhcpd_setup_route(addr, 128, iface, NULL, add);
322 }
323
324
325 // Handler for neighbor cache entries from the kernel. This is our source
326 // to learn and unlearn hosts on interfaces.
327 static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
328                 _unused struct interface *iface, _unused void *dest)
329 {
330         bool dump_neigh = false;
331         struct in6_addr last_solicited = IN6ADDR_ANY_INIT;
332
333         for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len);
334                         nh = NLMSG_NEXT(nh, len)) {
335                 struct rtmsg *rtm = NLMSG_DATA(nh);
336                 if ((nh->nlmsg_type == RTM_NEWROUTE ||
337                                 nh->nlmsg_type == RTM_DELROUTE) &&
338                                 rtm->rtm_dst_len == 0)
339                         raise(SIGUSR1); // Inform about a change in default route
340
341                 struct ndmsg *ndm = NLMSG_DATA(nh);
342                 struct ifaddrmsg *ifa = NLMSG_DATA(nh);
343                 if (nh->nlmsg_type != RTM_NEWNEIGH
344                                 && nh->nlmsg_type != RTM_DELNEIGH
345                                 && nh->nlmsg_type != RTM_NEWADDR
346                                 && nh->nlmsg_type != RTM_DELADDR)
347                         continue; // Unrelated message type
348                 bool is_addr = (nh->nlmsg_type == RTM_NEWADDR
349                                 || nh->nlmsg_type == RTM_DELADDR);
350
351                 // Family and ifindex are on the same offset for NEIGH and ADDR
352                 if (NLMSG_PAYLOAD(nh, 0) < sizeof(*ndm)
353                                 || ndm->ndm_family != AF_INET6)
354                         continue; //
355
356                 // Lookup interface
357                 struct interface *iface;
358                 if (!(iface = odhcpd_get_interface_by_index(ndm->ndm_ifindex)))
359                         continue;
360
361                 // Data to retrieve
362                 size_t rta_offset = (is_addr) ? sizeof(*ifa) : sizeof(*ndm);
363                 uint16_t atype = (is_addr) ? IFA_ADDRESS : NDA_DST;
364                 ssize_t alen = NLMSG_PAYLOAD(nh, rta_offset);
365                 struct in6_addr *addr = NULL;
366
367                 for (struct rtattr *rta = (void*)(((uint8_t*)ndm) + rta_offset);
368                                 RTA_OK(rta, alen); rta = RTA_NEXT(rta, alen))
369                         if (rta->rta_type == atype &&
370                                         RTA_PAYLOAD(rta) >= sizeof(*addr))
371                                 addr = RTA_DATA(rta);
372
373                 // Address not specified or unrelated
374                 if (!addr || IN6_IS_ADDR_LINKLOCAL(addr) ||
375                                 IN6_IS_ADDR_MULTICAST(addr))
376                         continue;
377
378                 // Check for states
379                 bool add;
380                 if (is_addr)
381                         add = (nh->nlmsg_type == RTM_NEWADDR);
382                 else
383                         add = (nh->nlmsg_type == RTM_NEWNEIGH && (ndm->ndm_state &
384                                 (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE
385                                                 | NUD_PERMANENT | NUD_NOARP)));
386
387                 if (iface->ndp == RELAYD_RELAY) {
388                         // Replay change to all neighbor cache
389                         struct {
390                                 struct nlmsghdr nh;
391                                 struct ndmsg ndm;
392                                 struct nlattr nla_dst;
393                                 struct in6_addr dst;
394                         } req = {
395                                 {sizeof(req), RTM_DELNEIGH, NLM_F_REQUEST,
396                                                 ++rtnl_seqid, 0},
397                                 {.ndm_family = AF_INET6, .ndm_flags = NTF_PROXY},
398                                 {sizeof(struct nlattr) + sizeof(struct in6_addr), NDA_DST},
399                                 *addr
400                         };
401
402                         if (ndm->ndm_flags & NTF_PROXY) {
403                                 // Dump & flush proxy entries
404                                 if (nh->nlmsg_type == RTM_NEWNEIGH) {
405                                         req.ndm.ndm_ifindex = iface->ifindex;
406                                         send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
407                                         setup_route(addr, iface, false);
408                                         dump_neigh = true;
409                                 }
410                         } else if (add) {
411                                 struct interface *c;
412                                 list_for_each_entry(c, &interfaces, head) {
413                                         if (iface == c)
414                                                 continue;
415
416                                         if (c->ndp == RELAYD_RELAY) {
417                                                 req.nh.nlmsg_type = RTM_NEWNEIGH;
418                                                 req.nh.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
419
420                                                 req.ndm.ndm_ifindex = c->ifindex;
421                                                 send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
422                                         } else { // Delete NDP cache from interfaces without relay
423                                                 req.nh.nlmsg_type = RTM_DELNEIGH;
424                                                 req.nh.nlmsg_flags &= ~(NLM_F_CREATE | NLM_F_REPLACE);
425
426                                                 req.ndm.ndm_ifindex = c->ifindex;
427                                                 send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
428                                         }
429                                 }
430
431                                 setup_route(addr, iface, true);
432                         } else {
433                                 if (nh->nlmsg_type == RTM_NEWNEIGH) {
434                                         // might be locally originating
435                                         if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
436                                                 last_solicited = *addr;
437
438                                                 struct interface *c;
439                                                 list_for_each_entry(c, &interfaces, head)
440                                                         if (iface->ndp == RELAYD_RELAY && iface != c &&
441                                                                         !c->external == false)
442                                                                 ping6(addr, c);
443                                         }
444                                 } else {
445                                         struct interface *c;
446                                         list_for_each_entry(c, &interfaces, head) {
447                                                 if (c->ndp == RELAYD_RELAY && iface != c) {
448                                                         req.ndm.ndm_ifindex = c->ifindex;
449                                                         send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
450                                                 }
451                                         }
452                                         setup_route(addr, iface, false);
453
454                                         // also: dump to add proxies back in case it moved elsewhere
455                                         dump_neigh = true;
456                                 }
457                         }
458                 }
459
460                 if (is_addr) {
461                         if (iface->ra == RELAYD_SERVER)
462                                 raise(SIGUSR1); // Inform about a change in addresses
463
464                         if (iface->dhcpv6 == RELAYD_SERVER)
465                                 iface->ia_reconf = true;
466
467                         if (iface->ndp == RELAYD_RELAY && iface->master) {
468                                 // Replay address changes on all slave interfaces
469                                 nh->nlmsg_flags = NLM_F_REQUEST;
470
471                                 if (nh->nlmsg_type == RTM_NEWADDR)
472                                         nh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
473
474                                 struct interface *c;
475                                 list_for_each_entry(c, &interfaces, head) {
476                                         if (c->ndp == RELAYD_RELAY && !c->master) {
477                                                 ifa->ifa_index = c->ifindex;
478                                                 send(rtnl_event.uloop.fd, nh, nh->nlmsg_len, MSG_DONTWAIT);
479                                         }
480                                 }
481                         }
482                 }
483         }
484
485         if (dump_neigh)
486                 dump_neigh_table(false);
487 }