1 /*
2 * Copyright (c) 2003
3 * Fraunhofer Institute for Open Communication Systems (FhG Fokus).
4 * All rights reserved.
5 *
6 * Author: Harti Brandt <harti@freebsd.org>
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $Begemot: bsnmp/snmpd/trans_udp.c,v 1.5 2005/10/04 08:46:56 brandt_h Exp $
30 *
31 * UDP transport
32 */
33 #include <sys/types.h>
34 #include <sys/queue.h>
35 #include <sys/ucred.h>
36
37 #include <stdbool.h>
38 #include <stdlib.h>
39 #include <syslog.h>
40 #include <string.h>
41 #include <errno.h>
42 #include <unistd.h>
43
44 #include <netinet/in.h>
45 #include <arpa/inet.h>
46
47 #include "snmpmod.h"
48 #include "snmpd.h"
49 #include "trans_udp.h"
50 #include "tree.h"
51 #include "oid.h"
52
53 static int udp_start(void);
54 static int udp_stop(int);
55 static void udp_close_port(struct tport *);
56 static int udp_init_port(struct tport *);
57 static ssize_t udp_send(struct tport *, const u_char *, size_t,
58 const struct sockaddr *, size_t);
59 static ssize_t udp_recv(struct tport *, struct port_input *);
60
61 /* exported */
62 const struct transport_def udp_trans = {
63 "udp",
64 OIDX_begemotSnmpdTransUdp,
65 udp_start,
66 udp_stop,
67 udp_close_port,
68 udp_init_port,
69 udp_send,
70 udp_recv,
71 NULL
72 };
73 static struct transport *my_trans;
74
75 static int
udp_start(void)76 udp_start(void)
77 {
78 return (trans_register(&udp_trans, &my_trans));
79 }
80
81 static int
udp_stop(int force __unused)82 udp_stop(int force __unused)
83 {
84 if (my_trans != NULL)
85 if (trans_unregister(my_trans) != 0)
86 return (SNMP_ERR_GENERR);
87 return (SNMP_ERR_NOERROR);
88 }
89
90 /*
91 * A UDP port is ready
92 */
93 static void
udp_input(int fd __unused,void * udata)94 udp_input(int fd __unused, void *udata)
95 {
96 struct udp_port *p = udata;
97
98 p->input.peerlen = sizeof(p->ret);
99 snmpd_input(&p->input, &p->tport);
100 }
101
102 /*
103 * Create a UDP socket and bind it to the given port
104 */
105 static int
udp_init_port(struct tport * tp)106 udp_init_port(struct tport *tp)
107 {
108 struct udp_port *p = (struct udp_port *)tp;
109 struct sockaddr_in addr;
110 u_int32_t ip;
111 const int on = 1;
112
113 if ((p->input.fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
114 syslog(LOG_ERR, "creating UDP socket: %m");
115 return (SNMP_ERR_RES_UNAVAIL);
116 }
117 ip = (p->addr[0] << 24) | (p->addr[1] << 16) | (p->addr[2] << 8) |
118 p->addr[3];
119 memset(&addr, 0, sizeof(addr));
120 addr.sin_addr.s_addr = htonl(ip);
121 addr.sin_port = htons(p->port);
122 addr.sin_family = AF_INET;
123 addr.sin_len = sizeof(addr);
124 if (addr.sin_addr.s_addr == INADDR_ANY) {
125 if (setsockopt(p->input.fd, IPPROTO_IP, IP_RECVDSTADDR, &on,
126 sizeof(on)) == -1) {
127 syslog(LOG_ERR, "setsockopt(IP_RECVDSTADDR): %m");
128 close(p->input.fd);
129 p->input.fd = -1;
130 return (SNMP_ERR_GENERR);
131 }
132 p->recvdstaddr = true;
133 }
134 if (bind(p->input.fd, (struct sockaddr *)&addr, sizeof(addr))) {
135 if (errno == EADDRNOTAVAIL) {
136 close(p->input.fd);
137 p->input.fd = -1;
138 return (SNMP_ERR_INCONS_NAME);
139 }
140 syslog(LOG_ERR, "bind: %s:%u %m", inet_ntoa(addr.sin_addr),
141 p->port);
142 close(p->input.fd);
143 p->input.fd = -1;
144 return (SNMP_ERR_GENERR);
145 }
146 if ((p->input.id = fd_select(p->input.fd, udp_input,
147 p, NULL)) == NULL) {
148 close(p->input.fd);
149 p->input.fd = -1;
150 return (SNMP_ERR_GENERR);
151 }
152 return (SNMP_ERR_NOERROR);
153 }
154
155 /*
156 * Create a new SNMP Port object and start it, if we are not
157 * in initialization mode. The arguments are in host byte order.
158 */
159 static int
udp_open_port(u_int8_t * addr,u_int32_t udp_port,struct udp_port ** pp)160 udp_open_port(u_int8_t *addr, u_int32_t udp_port, struct udp_port **pp)
161 {
162 struct udp_port *port;
163 int err;
164
165 if (udp_port > 0xffff)
166 return (SNMP_ERR_NO_CREATION);
167 if ((port = malloc(sizeof(*port))) == NULL)
168 return (SNMP_ERR_GENERR);
169 memset(port, 0, sizeof(*port));
170
171 /* initialize common part */
172 port->tport.index.len = 5;
173 port->tport.index.subs[0] = addr[0];
174 port->tport.index.subs[1] = addr[1];
175 port->tport.index.subs[2] = addr[2];
176 port->tport.index.subs[3] = addr[3];
177 port->tport.index.subs[4] = udp_port;
178
179 port->addr[0] = addr[0];
180 port->addr[1] = addr[1];
181 port->addr[2] = addr[2];
182 port->addr[3] = addr[3];
183 port->port = udp_port;
184
185 port->input.fd = -1;
186 port->input.id = NULL;
187 port->input.stream = 0;
188 port->input.cred = 0;
189 port->input.peer = (struct sockaddr *)&port->ret;
190 port->input.peerlen = sizeof(port->ret);
191
192 trans_insert_port(my_trans, &port->tport);
193
194 if (community != COMM_INITIALIZE &&
195 (err = udp_init_port(&port->tport)) != SNMP_ERR_NOERROR) {
196 udp_close_port(&port->tport);
197 return (err);
198 }
199 *pp = port;
200 return (SNMP_ERR_NOERROR);
201 }
202
203 /*
204 * Close an SNMP port
205 */
206 static void
udp_close_port(struct tport * tp)207 udp_close_port(struct tport *tp)
208 {
209 struct udp_port *port = (struct udp_port *)tp;
210
211 snmpd_input_close(&port->input);
212 trans_remove_port(tp);
213 free(port);
214 }
215
216 /*
217 * Send something
218 */
219 static ssize_t
udp_send(struct tport * tp,const u_char * buf,size_t len,const struct sockaddr * addr,size_t addrlen)220 udp_send(struct tport *tp, const u_char *buf, size_t len,
221 const struct sockaddr *addr, size_t addrlen)
222 {
223 struct udp_port *p = (struct udp_port *)tp;
224 struct cmsghdr *cmsg;
225 struct msghdr msg;
226 char cbuf[CMSG_SPACE(sizeof(struct in_addr))];
227 struct iovec iov;
228
229 iov.iov_base = __DECONST(void*, buf);
230 iov.iov_len = len;
231
232 msg.msg_flags = 0;
233 msg.msg_iov = &iov;
234 msg.msg_iovlen = 1;
235 msg.msg_name = __DECONST(void *, addr);
236 msg.msg_namelen = addrlen;
237
238 if (p->recvdstaddr) {
239 msg.msg_control = cbuf;
240 msg.msg_controllen = sizeof(cbuf);
241
242 cmsg = CMSG_FIRSTHDR(&msg);
243 cmsg->cmsg_level = IPPROTO_IP;
244 cmsg->cmsg_type = IP_SENDSRCADDR;
245 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
246 memcpy(CMSG_DATA(cmsg), &p->dstaddr, sizeof(struct in_addr));
247 } else {
248 msg.msg_control = NULL;
249 msg.msg_controllen = 0;
250 }
251
252 return (sendmsg(p->input.fd, &msg, 0));
253 }
254
255 static void
check_priv_dgram(struct port_input * pi,struct sockcred * cred)256 check_priv_dgram(struct port_input *pi, struct sockcred *cred)
257 {
258
259 /* process explicitly sends credentials */
260 if (cred)
261 pi->priv = (cred->sc_euid == 0);
262 else
263 pi->priv = 0;
264 }
265
266 /*
267 * Input from a datagram socket.
268 * Each receive should return one datagram.
269 */
270 static ssize_t
udp_recv(struct tport * tp,struct port_input * pi)271 udp_recv(struct tport *tp, struct port_input *pi)
272 {
273 u_char embuf[1000];
274 char cbuf[CMSG_SPACE(SOCKCREDSIZE(CMGROUP_MAX)) +
275 CMSG_SPACE(sizeof(struct in_addr))];
276 struct udp_port *p = (struct udp_port *)tp;
277 struct msghdr msg;
278 struct iovec iov[1];
279 ssize_t len;
280 struct cmsghdr *cmsg;
281 struct sockcred *cred = NULL;
282
283 if (pi->buf == NULL) {
284 /* no buffer yet - allocate one */
285 if ((pi->buf = buf_alloc(0)) == NULL) {
286 /* ups - could not get buffer. Read away input
287 * and drop it */
288 (void)recvfrom(pi->fd, embuf, sizeof(embuf),
289 0, NULL, NULL);
290 /* return error */
291 return (-1);
292 }
293 pi->buflen = buf_size(0);
294 }
295
296 /* try to get a message */
297 msg.msg_name = pi->peer;
298 msg.msg_namelen = pi->peerlen;
299 msg.msg_iov = iov;
300 msg.msg_iovlen = 1;
301 memset(cbuf, 0, sizeof(cbuf));
302 msg.msg_control = cbuf;
303 msg.msg_controllen = sizeof(cbuf);
304 msg.msg_flags = 0;
305
306 iov[0].iov_base = pi->buf;
307 iov[0].iov_len = pi->buflen;
308
309 len = recvmsg(pi->fd, &msg, 0);
310
311 if (len == -1 || len == 0)
312 /* receive error */
313 return (-1);
314
315 if (msg.msg_flags & MSG_TRUNC) {
316 /* truncated - drop */
317 snmpd_stats.silentDrops++;
318 snmpd_stats.inTooLong++;
319 return (-1);
320 }
321
322 pi->length = (size_t)len;
323
324 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
325 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
326 if (cmsg->cmsg_level == IPPROTO_IP &&
327 cmsg->cmsg_type == IP_RECVDSTADDR)
328 memcpy(&p->dstaddr, CMSG_DATA(cmsg),
329 sizeof(struct in_addr));
330 if (cmsg->cmsg_level == SOL_SOCKET &&
331 cmsg->cmsg_type == SCM_CREDS)
332 cred = (struct sockcred *)(void *)CMSG_DATA(cmsg);
333 }
334
335 if (pi->cred)
336 check_priv_dgram(pi, cred);
337
338 return (0);
339 }
340
341 /*
342 * Port table
343 */
344 int
op_snmp_port(struct snmp_context * ctx,struct snmp_value * value,u_int sub,u_int iidx,enum snmp_op op)345 op_snmp_port(struct snmp_context *ctx, struct snmp_value *value,
346 u_int sub, u_int iidx, enum snmp_op op)
347 {
348 asn_subid_t which = value->var.subs[sub-1];
349 struct udp_port *p;
350 u_int8_t addr[4];
351 u_int32_t port;
352
353 switch (op) {
354
355 case SNMP_OP_GETNEXT:
356 if ((p = (struct udp_port *)trans_next_port(my_trans,
357 &value->var, sub)) == NULL)
358 return (SNMP_ERR_NOSUCHNAME);
359 index_append(&value->var, sub, &p->tport.index);
360 break;
361
362 case SNMP_OP_GET:
363 if ((p = (struct udp_port *)trans_find_port(my_trans,
364 &value->var, sub)) == NULL)
365 return (SNMP_ERR_NOSUCHNAME);
366 break;
367
368 case SNMP_OP_SET:
369 p = (struct udp_port *)trans_find_port(my_trans,
370 &value->var, sub);
371 ctx->scratch->int1 = (p != NULL);
372
373 if (which != LEAF_begemotSnmpdPortStatus)
374 abort();
375 if (!TRUTH_OK(value->v.integer))
376 return (SNMP_ERR_WRONG_VALUE);
377
378 ctx->scratch->int2 = TRUTH_GET(value->v.integer);
379
380 if (ctx->scratch->int2) {
381 /* open an SNMP port */
382 if (p != NULL)
383 /* already open - do nothing */
384 return (SNMP_ERR_NOERROR);
385
386 if (index_decode(&value->var, sub, iidx, addr, &port))
387 return (SNMP_ERR_NO_CREATION);
388 return (udp_open_port(addr, port, &p));
389
390 } else {
391 /* close SNMP port - do in commit */
392 }
393 return (SNMP_ERR_NOERROR);
394
395 case SNMP_OP_ROLLBACK:
396 p = (struct udp_port *)trans_find_port(my_trans,
397 &value->var, sub);
398 if (ctx->scratch->int1 == 0) {
399 /* did not exist */
400 if (ctx->scratch->int2 == 1) {
401 /* created */
402 if (p != NULL)
403 udp_close_port(&p->tport);
404 }
405 }
406 return (SNMP_ERR_NOERROR);
407
408 case SNMP_OP_COMMIT:
409 p = (struct udp_port *)trans_find_port(my_trans,
410 &value->var, sub);
411 if (ctx->scratch->int1 == 1) {
412 /* did exist */
413 if (ctx->scratch->int2 == 0) {
414 /* delete */
415 if (p != NULL)
416 udp_close_port(&p->tport);
417 }
418 }
419 return (SNMP_ERR_NOERROR);
420
421 default:
422 abort();
423 }
424
425 /*
426 * Come here to fetch the value
427 */
428 switch (which) {
429
430 case LEAF_begemotSnmpdPortStatus:
431 value->v.integer = 1;
432 break;
433
434 default:
435 abort();
436 }
437
438 return (SNMP_ERR_NOERROR);
439 }
440