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