1 /* $OpenBSD: packet.c,v 1.37 2023/07/03 09:40:47 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20 #include <sys/socket.h>
21 #include <sys/uio.h>
22
23 #include <netinet/in.h>
24 #include <netinet/ip.h>
25 #include <arpa/inet.h>
26 #include <net/if_dl.h>
27
28 #include <errno.h>
29 #include <event.h>
30 #include <stdlib.h>
31 #include <string.h>
32
33 #include "ospfd.h"
34 #include "ospf.h"
35 #include "log.h"
36 #include "ospfe.h"
37
38 int ip_hdr_sanity_check(const struct ip *, u_int16_t);
39 int ospf_hdr_sanity_check(const struct ip *,
40 struct ospf_hdr *, u_int16_t, const struct iface *);
41 struct iface *find_iface(struct ospfd_conf *, unsigned int, struct in_addr);
42
43 static u_int8_t *recv_buf;
44
45 int
gen_ospf_hdr(struct ibuf * buf,struct iface * iface,u_int8_t type)46 gen_ospf_hdr(struct ibuf *buf, struct iface *iface, u_int8_t type)
47 {
48 struct ospf_hdr ospf_hdr;
49
50 bzero(&ospf_hdr, sizeof(ospf_hdr));
51 ospf_hdr.version = OSPF_VERSION;
52 ospf_hdr.type = type;
53 ospf_hdr.rtr_id = ospfe_router_id();
54 if (iface->type != IF_TYPE_VIRTUALLINK)
55 ospf_hdr.area_id = iface->area->id.s_addr;
56 ospf_hdr.auth_type = htons(iface->auth_type);
57
58 return (ibuf_add(buf, &ospf_hdr, sizeof(ospf_hdr)));
59 }
60
61 /* send and receive packets */
62 int
send_packet(struct iface * iface,struct ibuf * buf,struct sockaddr_in * dst)63 send_packet(struct iface *iface, struct ibuf *buf, struct sockaddr_in *dst)
64 {
65 struct msghdr msg;
66 struct iovec iov[2];
67 struct ip ip_hdr;
68
69 /* setup IP hdr */
70 bzero(&ip_hdr, sizeof(ip_hdr));
71 ip_hdr.ip_v = IPVERSION;
72 ip_hdr.ip_hl = sizeof(ip_hdr) >> 2;
73 ip_hdr.ip_tos = IPTOS_PREC_INTERNETCONTROL;
74 ip_hdr.ip_len = htons(ibuf_size(buf) + sizeof(ip_hdr));
75 ip_hdr.ip_id = 0; /* 0 means kernel set appropriate value */
76 ip_hdr.ip_off = 0;
77 ip_hdr.ip_ttl = iface->type != IF_TYPE_VIRTUALLINK ?
78 IP_DEFAULT_MULTICAST_TTL : MAXTTL;
79 ip_hdr.ip_p = IPPROTO_OSPF;
80 ip_hdr.ip_sum = 0;
81 ip_hdr.ip_src = iface->addr;
82 ip_hdr.ip_dst = dst->sin_addr;
83
84 /* setup buffer */
85 bzero(&msg, sizeof(msg));
86 iov[0].iov_base = &ip_hdr;
87 iov[0].iov_len = sizeof(ip_hdr);
88 iov[1].iov_base = ibuf_data(buf);
89 iov[1].iov_len = ibuf_size(buf);
90 msg.msg_name = dst;
91 msg.msg_namelen = sizeof(*dst);
92 msg.msg_iov = iov;
93 msg.msg_iovlen = 2;
94
95 /* set outgoing interface for multicast traffic */
96 if (IN_MULTICAST(ntohl(dst->sin_addr.s_addr)))
97 if (if_set_mcast(iface) == -1)
98 return (-1);
99
100 if (sendmsg(iface->fd, &msg, 0) == -1) {
101 log_warn("%s: error sending packet to %s on interface %s",
102 __func__, inet_ntoa(ip_hdr.ip_dst), iface->name);
103 return (-1);
104 }
105
106 return (0);
107 }
108
109 void
recv_packet(int fd,short event,void * bula)110 recv_packet(int fd, short event, void *bula)
111 {
112 union {
113 struct cmsghdr hdr;
114 char buf[CMSG_SPACE(sizeof(struct sockaddr_dl))];
115 } cmsgbuf;
116 struct msghdr msg;
117 struct iovec iov;
118 struct ip ip_hdr;
119 struct in_addr addr;
120 struct ospfd_conf *xconf = bula;
121 struct ospf_hdr *ospf_hdr;
122 struct iface *iface;
123 struct nbr *nbr = NULL;
124 char *buf;
125 struct cmsghdr *cmsg;
126 ssize_t r;
127 u_int16_t len;
128 int l;
129 unsigned int ifindex = 0;
130
131 if (event != EV_READ)
132 return;
133
134 if (recv_buf == NULL)
135 if ((recv_buf = malloc(READ_BUF_SIZE)) == NULL)
136 fatal(__func__);
137
138 /* setup buffer */
139 bzero(&msg, sizeof(msg));
140 iov.iov_base = buf = recv_buf;
141 iov.iov_len = READ_BUF_SIZE;
142 msg.msg_iov = &iov;
143 msg.msg_iovlen = 1;
144 msg.msg_control = &cmsgbuf.buf;
145 msg.msg_controllen = sizeof(cmsgbuf.buf);
146
147 if ((r = recvmsg(fd, &msg, 0)) == -1) {
148 if (errno != EAGAIN && errno != EINTR)
149 log_debug("recv_packet: read error: %s",
150 strerror(errno));
151 return;
152 }
153 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
154 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
155 if (cmsg->cmsg_level == IPPROTO_IP &&
156 cmsg->cmsg_type == IP_RECVIF) {
157 ifindex = ((struct sockaddr_dl *)
158 CMSG_DATA(cmsg))->sdl_index;
159 break;
160 }
161 }
162
163 len = (u_int16_t)r;
164
165 /* IP header sanity checks */
166 if (len < sizeof(ip_hdr)) {
167 log_warnx("recv_packet: bad packet size");
168 return;
169 }
170 memcpy(&ip_hdr, buf, sizeof(ip_hdr));
171 if ((l = ip_hdr_sanity_check(&ip_hdr, len)) == -1)
172 return;
173 buf += l;
174 len -= l;
175
176 /* find a matching interface */
177 if ((iface = find_iface(xconf, ifindex, ip_hdr.ip_src)) == NULL) {
178 /* XXX add a counter here */
179 return;
180 }
181
182 /*
183 * Packet needs to be sent to AllSPFRouters or AllDRouters
184 * or to the address of the interface itself.
185 * AllDRouters is only valid for DR and BDR but this is checked later.
186 */
187 inet_aton(AllSPFRouters, &addr);
188 if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
189 inet_aton(AllDRouters, &addr);
190 if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
191 if (ip_hdr.ip_dst.s_addr != iface->addr.s_addr) {
192 log_debug("recv_packet: packet sent to wrong "
193 "address %s, interface %s",
194 inet_ntoa(ip_hdr.ip_dst), iface->name);
195 return;
196 }
197 }
198 }
199
200 /* OSPF header sanity checks */
201 if (len < sizeof(*ospf_hdr)) {
202 log_debug("recv_packet: bad packet size");
203 return;
204 }
205 ospf_hdr = (struct ospf_hdr *)buf;
206
207 if ((l = ospf_hdr_sanity_check(&ip_hdr, ospf_hdr, len, iface)) == -1)
208 return;
209
210 nbr = nbr_find_id(iface, ospf_hdr->rtr_id);
211 if (ospf_hdr->type != PACKET_TYPE_HELLO && nbr == NULL) {
212 log_debug("recv_packet: unknown neighbor ID");
213 return;
214 }
215
216 if (auth_validate(buf, len, iface, nbr)) {
217 if (nbr == NULL)
218 log_warnx("recv_packet: authentication error, "
219 "interface %s", iface->name);
220 else
221 log_warnx("recv_packet: authentication error, "
222 "neighbor ID %s interface %s",
223 inet_ntoa(nbr->id), iface->name);
224 return;
225 }
226
227 buf += sizeof(*ospf_hdr);
228 len = l - sizeof(*ospf_hdr);
229
230 /* switch OSPF packet type */
231 switch (ospf_hdr->type) {
232 case PACKET_TYPE_HELLO:
233 inet_aton(AllSPFRouters, &addr);
234 if (iface->type == IF_TYPE_BROADCAST ||
235 iface->type == IF_TYPE_POINTOPOINT)
236 if (ip_hdr.ip_dst.s_addr != addr.s_addr) {
237 log_warnx("%s: hello ignored on interface %s, "
238 "invalid destination IP address %s",
239 __func__, iface->name,
240 inet_ntoa(ip_hdr.ip_dst));
241 break;
242 }
243
244 recv_hello(iface, ip_hdr.ip_src, ospf_hdr->rtr_id, buf, len);
245 break;
246 case PACKET_TYPE_DD:
247 recv_db_description(nbr, buf, len);
248 break;
249 case PACKET_TYPE_LS_REQUEST:
250 recv_ls_req(nbr, buf, len);
251 break;
252 case PACKET_TYPE_LS_UPDATE:
253 recv_ls_update(nbr, buf, len);
254 break;
255 case PACKET_TYPE_LS_ACK:
256 recv_ls_ack(nbr, buf, len);
257 break;
258 default:
259 log_debug("recv_packet: unknown OSPF packet type, interface %s",
260 iface->name);
261 }
262 }
263
264 int
ip_hdr_sanity_check(const struct ip * ip_hdr,u_int16_t len)265 ip_hdr_sanity_check(const struct ip *ip_hdr, u_int16_t len)
266 {
267 if (ntohs(ip_hdr->ip_len) != len) {
268 log_debug("recv_packet: invalid IP packet length %u",
269 ntohs(ip_hdr->ip_len));
270 return (-1);
271 }
272
273 if (ip_hdr->ip_p != IPPROTO_OSPF)
274 /* this is enforced by the socket itself */
275 fatalx("recv_packet: invalid IP proto");
276
277 return (ip_hdr->ip_hl << 2);
278 }
279
280 int
ospf_hdr_sanity_check(const struct ip * ip_hdr,struct ospf_hdr * ospf_hdr,u_int16_t len,const struct iface * iface)281 ospf_hdr_sanity_check(const struct ip *ip_hdr, struct ospf_hdr *ospf_hdr,
282 u_int16_t len, const struct iface *iface)
283 {
284 struct in_addr addr;
285
286 if (ospf_hdr->version != OSPF_VERSION) {
287 log_debug("recv_packet: invalid OSPF version %d",
288 ospf_hdr->version);
289 return (-1);
290 }
291
292 if (ntohs(ospf_hdr->len) > len ||
293 len <= sizeof(struct ospf_hdr)) {
294 log_debug("recv_packet: invalid OSPF packet length %d",
295 ntohs(ospf_hdr->len));
296 return (-1);
297 }
298
299 if (iface->type != IF_TYPE_VIRTUALLINK) {
300 if (ospf_hdr->area_id != iface->area->id.s_addr) {
301 addr.s_addr = ospf_hdr->area_id;
302 log_debug("recv_packet: invalid area ID %s, "
303 "interface %s", inet_ntoa(addr), iface->name);
304 return (-1);
305 }
306 } else {
307 if (ospf_hdr->area_id != 0) {
308 addr.s_addr = ospf_hdr->area_id;
309 log_debug("recv_packet: invalid area ID %s, "
310 "interface %s", inet_ntoa(addr), iface->name);
311 return (-1);
312 }
313 }
314
315 if (iface->type == IF_TYPE_BROADCAST || iface->type == IF_TYPE_NBMA) {
316 if (inet_aton(AllDRouters, &addr) == 0)
317 fatalx("recv_packet: inet_aton");
318 if (ip_hdr->ip_dst.s_addr == addr.s_addr &&
319 (iface->state & IF_STA_DRORBDR) == 0) {
320 log_debug("recv_packet: invalid destination IP in "
321 "state %s, interface %s",
322 if_state_name(iface->state), iface->name);
323 return (-1);
324 }
325 }
326
327 return (ntohs(ospf_hdr->len));
328 }
329
330 struct iface *
find_iface(struct ospfd_conf * xconf,unsigned int ifindex,struct in_addr src)331 find_iface(struct ospfd_conf *xconf, unsigned int ifindex, struct in_addr src)
332 {
333 struct area *area = NULL;
334 struct iface *iface = NULL;
335
336 /* returned interface needs to be active */
337 LIST_FOREACH(area, &xconf->area_list, entry) {
338 LIST_FOREACH(iface, &area->iface_list, entry) {
339 switch (iface->type) {
340 case IF_TYPE_VIRTUALLINK:
341 if ((src.s_addr == iface->dst.s_addr) &&
342 !iface->passive)
343 return (iface);
344 break;
345 case IF_TYPE_POINTOPOINT:
346 if (ifindex == iface->ifindex &&
347 !iface->passive)
348 return (iface);
349 break;
350 default:
351 if (ifindex == iface->ifindex &&
352 (iface->addr.s_addr & iface->mask.s_addr) ==
353 (src.s_addr & iface->mask.s_addr) &&
354 !iface->passive)
355 return (iface);
356 break;
357 }
358 }
359 }
360
361 return (NULL);
362 }
363