summaryrefslogtreecommitdiff
path: root/usr.sbin/snmpd/snmpd.c
blob: 61b9f6ffac548c6ab5e363203e0d578383247ebf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
/*	$OpenBSD: snmpd.c,v 1.12 2012/09/17 16:30:35 reyk Exp $	*/

/*
 * Copyright (c) 2007, 2008 Reyk Floeter <reyk@vantronix.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/param.h>
#include <sys/wait.h>
#include <sys/tree.h>

#include <net/if.h>

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <err.h>
#include <errno.h>
#include <event.h>
#include <signal.h>
#include <unistd.h>
#include <pwd.h>

#include "snmpd.h"
#include "mib.h"

__dead void	 usage(void);

void		 snmpd_sig_handler(int, short, void *);
void		 snmpd_shutdown(struct snmpd *);
void		 snmpd_dispatch_snmpe(int, short, void *);
int		 check_child(pid_t, const char *);
void		 snmpd_generate_engineid(struct snmpd *);

struct snmpd	*snmpd_env;

int		 pipe_parent2snmpe[2];
struct imsgev	*iev_snmpe;
pid_t		 snmpe_pid = 0;

void
snmpd_sig_handler(int sig, short event, void *arg)
{
	struct snmpd	*env = arg;
	int			 die = 0;

	switch (sig) {
	case SIGTERM:
	case SIGINT:
		die = 1;
		/* FALLTHROUGH */
	case SIGCHLD:
		if (check_child(snmpe_pid, "snmp engine")) {
			snmpe_pid = 0;
			die  = 1;
		}
		if (die)
			snmpd_shutdown(env);
		break;
	case SIGHUP:
		/* reconfigure */
		break;
	default:
		fatalx("unexpected signal");
	}
}

/* __dead is for lint */
__dead void
usage(void)
{
	extern char	*__progname;

	fprintf(stderr, "usage: %s [-dNnv] [-D macro=value] "
	    "[-f file] [-r path]\n", __progname);
	exit(1);
}

int
main(int argc, char *argv[])
{
	int			 c;
	struct snmpd		*env;
	struct event		 ev_sigint;
	struct event		 ev_sigterm;
	struct event		 ev_sigchld;
	struct event		 ev_sighup;
	int			 debug = 0;
	u_int			 flags = 0;
	int			 noaction = 0;
	const char		*conffile = CONF_FILE;
	const char		*rcsock = NULL;

	smi_init();

	log_init(1);	/* log to stderr until daemonized */

	while ((c = getopt(argc, argv, "dD:nNf:r:v")) != -1) {
		switch (c) {
		case 'd':
			debug = 1;
			break;
		case 'D':
			if (cmdline_symset(optarg) < 0)
				log_warnx("could not parse macro definition %s",
				    optarg);
			break;
		case 'n':
			noaction++;
			break;
		case 'N':
			flags |= SNMPD_F_NONAMES;
			break;
		case 'f':
			conffile = optarg;
			break;
		case 'r':
			rcsock = optarg;
			break;
		case 'v':
			flags |= SNMPD_F_VERBOSE;
			break;
		default:
			usage();
		}
	}

	argc -= optind;
	argv += optind;
	if (argc > 0)
		usage();

	if ((env = parse_config(conffile, flags)) == NULL)
		exit(1);
	snmpd_env = env;

	if (noaction) {
		fprintf(stderr, "configuration ok\n");
		exit(0);
	}

	if (geteuid())
		errx(1, "need root privileges");

	if (getpwnam(SNMPD_USER) == NULL)
		errx(1, "unknown user %s", SNMPD_USER);

	/* Configure the control sockets */
	env->sc_csock.cs_name = SNMPD_SOCKET;
	env->sc_rcsock.cs_name = rcsock;
	env->sc_rcsock.cs_restricted = 1;

	log_init(debug);

	if (!debug) {
		if (daemon(1, 0) == -1)
			err(1, "failed to daemonize");
	}

	gettimeofday(&env->sc_starttime, NULL);
	env->sc_engine_boots = 0;

	log_info("startup");

	pf_init();

	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC,
	    pipe_parent2snmpe) == -1)
		fatal("socketpair");

	session_socket_blockmode(pipe_parent2snmpe[0], BM_NONBLOCK);
	session_socket_blockmode(pipe_parent2snmpe[1], BM_NONBLOCK);

	snmpd_generate_engineid(env);

	snmpe_pid = snmpe(env, pipe_parent2snmpe);
	setproctitle("parent");

	event_init();

	signal_set(&ev_sigint, SIGINT, snmpd_sig_handler, env);
	signal_set(&ev_sigterm, SIGTERM, snmpd_sig_handler, env);
	signal_set(&ev_sigchld, SIGCHLD, snmpd_sig_handler, env);
	signal_set(&ev_sighup, SIGHUP, snmpd_sig_handler, env);
	signal_add(&ev_sigint, NULL);
	signal_add(&ev_sigterm, NULL);
	signal_add(&ev_sigchld, NULL);
	signal_add(&ev_sighup, NULL);
	signal(SIGPIPE, SIG_IGN);

	close(pipe_parent2snmpe[1]);

	if ((iev_snmpe = calloc(1, sizeof(struct imsgev))) == NULL)
		fatal(NULL);

	imsg_init(&iev_snmpe->ibuf, pipe_parent2snmpe[0]);
	iev_snmpe->handler = snmpd_dispatch_snmpe;

	iev_snmpe->events = EV_READ;
	event_set(&iev_snmpe->ev, iev_snmpe->ibuf.fd, iev_snmpe->events,
	    iev_snmpe->handler, iev_snmpe);
	event_add(&iev_snmpe->ev, NULL);

	event_dispatch();

	return (0);
}

void
snmpd_shutdown(struct snmpd *env)
{
	pid_t	pid;

	if (snmpe_pid)
		kill(snmpe_pid, SIGTERM);

	do {
		if ((pid = wait(NULL)) == -1 &&
		    errno != EINTR && errno != ECHILD)
			fatal("wait");
	} while (pid != -1 || (pid == -1 && errno == EINTR));

	control_cleanup(&env->sc_csock);
	control_cleanup(&env->sc_rcsock);
	log_info("terminating");
	exit(0);
}

int
check_child(pid_t pid, const char *pname)
{
	int	status;

	if (waitpid(pid, &status, WNOHANG) > 0) {
		if (WIFEXITED(status)) {
			log_warnx("check_child: lost child: %s exited", pname);
			return (1);
		}
		if (WIFSIGNALED(status)) {
			log_warnx("check_child: lost child: %s terminated; "
			    "signal %d", pname, WTERMSIG(status));
			return (1);
		}
	}

	return (0);
}

void
imsg_event_add(struct imsgev *iev)
{
	iev->events = EV_READ;
	if (iev->ibuf.w.queued)
		iev->events |= EV_WRITE;

	event_del(&iev->ev);
	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev);
	event_add(&iev->ev, NULL);
}

void
snmpd_dispatch_snmpe(int fd, short event, void * ptr)
{
	struct imsgev		*iev;
	struct imsgbuf		*ibuf;
	struct imsg		 imsg;
	ssize_t			 n;

	iev = ptr;
	ibuf = &iev->ibuf;
	switch (event) {
	case EV_READ:
		if ((n = imsg_read(ibuf)) == -1)
			fatal("imsg_read error");
		if (n == 0) {
			/* this pipe is dead, so remove the event handler */
			event_del(&iev->ev);
			event_loopexit(NULL);
			return;
		}
		break;
	case EV_WRITE:
		if (msgbuf_write(&ibuf->w) == -1)
			fatal("msgbuf_write");
		imsg_event_add(iev);
		return;
	default:
		fatalx("unknown event");
	}

	for (;;) {
		if ((n = imsg_get(ibuf, &imsg)) == -1)
			fatal("snmpd_dispatch_relay: imsg_read error");
		if (n == 0)
			break;

		switch (imsg.hdr.type) {
		default:
			log_debug("snmpd_dispatch_relay: unexpected imsg %d",
			    imsg.hdr.type);
			break;
		}
		imsg_free(&imsg);
	}
	imsg_event_add(iev);
}

int
snmpd_socket_af(struct sockaddr_storage *ss, in_port_t port)
{
	int	 s;

	switch (ss->ss_family) {
	case AF_INET:
		((struct sockaddr_in *)ss)->sin_port = port;
		((struct sockaddr_in *)ss)->sin_len =
		    sizeof(struct sockaddr_in);
		break;
	case AF_INET6:
		((struct sockaddr_in6 *)ss)->sin6_port = port;
		((struct sockaddr_in6 *)ss)->sin6_len =
		    sizeof(struct sockaddr_in6);
		break;
	default:
		return (-1);
	}

	s = socket(ss->ss_family, SOCK_DGRAM, IPPROTO_UDP);
	return (s);
}

void
snmpd_generate_engineid(struct snmpd *env)
{
	u_int32_t		 oid_enterprise, rnd, tim;

	/* RFC 3411 */
	memset(env->sc_engineid, 0, sizeof (env->sc_engineid));
	oid_enterprise = htonl(OIDVAL_openBSD_eid);
	memcpy(env->sc_engineid, &oid_enterprise, sizeof (oid_enterprise));
	env->sc_engineid[0] |= SNMP_ENGINEID_NEW;
	env->sc_engineid_len = sizeof (oid_enterprise);
	/* XXX alternatively configure engine id via snmpd.conf */
	env->sc_engineid[(env->sc_engineid_len)++] = SNMP_ENGINEID_FMT_EID;
	rnd = arc4random();
	memcpy(&env->sc_engineid[env->sc_engineid_len], &rnd, sizeof (rnd));
	env->sc_engineid_len += sizeof (rnd);
	tim = htonl(env->sc_starttime.tv_sec);
	memcpy(&env->sc_engineid[env->sc_engineid_len], &tim, sizeof (tim));
	env->sc_engineid_len += sizeof (tim);
	return;
}

u_long
snmpd_engine_time(void)
{
	struct timeval	 now;

	/*
	 * snmpEngineBoots should be stored in a non-volatile storage.
	 * snmpEngineTime is the number of seconds since snmpEngineBoots
	 * was last incremented. We don't rely on non-volatile storage.
	 * snmpEngineBoots is set to zero and snmpEngineTime to the system
	 * clock. Hence, the tuple (snmpEngineBoots, snmpEngineTime) is
	 * still unique and protects us against replay attacks. It only
	 * 'expires' a little bit sooner than the RFC3414 method.
	 */
	gettimeofday(&now, NULL);
	return now.tv_sec;
}

char *
tohexstr(u_int8_t *str, int len)
{
#define MAXHEXSTRLEN		256
	static char hstr[2 * MAXHEXSTRLEN + 1];
	char *r = hstr;

	if (len > MAXHEXSTRLEN)
		len = MAXHEXSTRLEN;	/* truncate */
	while (len-- > 0)
		r += snprintf(r, len * 2, "%0*x", 2, *str++);
	*r = '\0';
	return hstr;
}