xref: /freebsd/sbin/dumpon/dumpon.c (revision a9490b81b032b43cdb3c8c76b4d01bbad9ff82c1)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1980, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #if 0
33 #ifndef lint
34 static const char copyright[] =
35 "@(#) Copyright (c) 1980, 1993\n\
36 	The Regents of the University of California.  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #ifndef lint
40 static char sccsid[] = "From: @(#)swapon.c	8.1 (Berkeley) 6/5/93";
41 #endif /* not lint */
42 #endif
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
45 
46 #include <sys/param.h>
47 #include <sys/capsicum.h>
48 #include <sys/disk.h>
49 #include <sys/socket.h>
50 #include <sys/sysctl.h>
51 #include <sys/wait.h>
52 
53 #include <assert.h>
54 #include <capsicum_helpers.h>
55 #include <err.h>
56 #include <errno.h>
57 #include <fcntl.h>
58 #include <ifaddrs.h>
59 #include <netdb.h>
60 #include <paths.h>
61 #include <stdbool.h>
62 #include <stdint.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <string.h>
66 #include <sysexits.h>
67 #include <unistd.h>
68 
69 #include <arpa/inet.h>
70 
71 #include <net/if.h>
72 #include <net/if_dl.h>
73 #include <net/route.h>
74 
75 #include <netinet/in.h>
76 #include <netinet/netdump/netdump.h>
77 
78 #ifdef HAVE_CRYPTO
79 #include <openssl/err.h>
80 #include <openssl/pem.h>
81 #include <openssl/rand.h>
82 #include <openssl/rsa.h>
83 #endif
84 
85 static int	verbose;
86 
87 static void _Noreturn
88 usage(void)
89 {
90 	fprintf(stderr,
91     "usage: dumpon [-i index] [-r] [-v] [-k <pubkey>] [-Zz] <device>\n"
92     "       dumpon [-i index] [-r] [-v] [-k <pubkey>] [-Zz]\n"
93     "              [-g <gateway>] -s <server> -c <client> <iface>\n"
94     "       dumpon [-v] off\n"
95     "       dumpon [-v] -l\n");
96 	exit(EX_USAGE);
97 }
98 
99 /*
100  * Look for a default route on the specified interface.
101  */
102 static char *
103 find_gateway(const char *ifname)
104 {
105 	struct ifaddrs *ifa, *ifap;
106 	struct rt_msghdr *rtm;
107 	struct sockaddr *sa;
108 	struct sockaddr_dl *sdl;
109 	struct sockaddr_in *dst, *mask, *gw;
110 	char *buf, *next, *ret;
111 	size_t sz;
112 	int error, i, ifindex, mib[7];
113 
114 	/* First look up the interface index. */
115 	if (getifaddrs(&ifap) != 0)
116 		err(EX_OSERR, "getifaddrs");
117 	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
118 		if (ifa->ifa_addr->sa_family != AF_LINK)
119 			continue;
120 		if (strcmp(ifa->ifa_name, ifname) == 0) {
121 			sdl = (struct sockaddr_dl *)(void *)ifa->ifa_addr;
122 			ifindex = sdl->sdl_index;
123 			break;
124 		}
125 	}
126 	if (ifa == NULL)
127 		errx(1, "couldn't find interface index for '%s'", ifname);
128 	freeifaddrs(ifap);
129 
130 	/* Now get the IPv4 routing table. */
131 	mib[0] = CTL_NET;
132 	mib[1] = PF_ROUTE;
133 	mib[2] = 0;
134 	mib[3] = AF_INET;
135 	mib[4] = NET_RT_DUMP;
136 	mib[5] = 0;
137 	mib[6] = -1; /* FIB */
138 
139 	for (;;) {
140 		if (sysctl(mib, nitems(mib), NULL, &sz, NULL, 0) != 0)
141 			err(EX_OSERR, "sysctl(NET_RT_DUMP)");
142 		buf = malloc(sz);
143 		error = sysctl(mib, nitems(mib), buf, &sz, NULL, 0);
144 		if (error == 0)
145 			break;
146 		if (errno != ENOMEM)
147 			err(EX_OSERR, "sysctl(NET_RT_DUMP)");
148 		free(buf);
149 	}
150 
151 	ret = NULL;
152 	for (next = buf; next < buf + sz; next += rtm->rtm_msglen) {
153 		rtm = (struct rt_msghdr *)(void *)next;
154 		if (rtm->rtm_version != RTM_VERSION)
155 			continue;
156 		if ((rtm->rtm_flags & RTF_GATEWAY) == 0 ||
157 		    rtm->rtm_index != ifindex)
158 			continue;
159 
160 		dst = gw = mask = NULL;
161 		sa = (struct sockaddr *)(rtm + 1);
162 		for (i = 0; i < RTAX_MAX; i++) {
163 			if ((rtm->rtm_addrs & (1 << i)) != 0) {
164 				switch (i) {
165 				case RTAX_DST:
166 					dst = (void *)sa;
167 					break;
168 				case RTAX_GATEWAY:
169 					gw = (void *)sa;
170 					break;
171 				case RTAX_NETMASK:
172 					mask = (void *)sa;
173 					break;
174 				}
175 			}
176 			sa = (struct sockaddr *)((char *)sa + SA_SIZE(sa));
177 		}
178 
179 		if (dst->sin_addr.s_addr == INADDR_ANY &&
180 		    mask->sin_addr.s_addr == 0) {
181 			ret = inet_ntoa(gw->sin_addr);
182 			break;
183 		}
184 	}
185 	free(buf);
186 	return (ret);
187 }
188 
189 static void
190 check_link_status(const char *ifname)
191 {
192 	struct ifaddrs *ifap, *ifa;
193 
194 	if (getifaddrs(&ifap) != 0)
195 		err(EX_OSERR, "getifaddrs");
196 
197 	for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next) {
198 		if (strcmp(ifname, ifa->ifa_name) != 0)
199 			continue;
200 		if ((ifa->ifa_flags & IFF_UP) == 0) {
201 			warnx("warning: %s's link is down", ifname);
202 		}
203 		break;
204 	}
205 	freeifaddrs(ifap);
206 }
207 
208 static void
209 check_size(int fd, const char *fn)
210 {
211 	int name[] = { CTL_HW, HW_PHYSMEM };
212 	size_t namelen = nitems(name);
213 	unsigned long physmem;
214 	size_t len;
215 	off_t mediasize;
216 	int minidump;
217 
218 	len = sizeof(minidump);
219 	if (sysctlbyname("debug.minidump", &minidump, &len, NULL, 0) == 0 &&
220 	    minidump == 1)
221 		return;
222 	len = sizeof(physmem);
223 	if (sysctl(name, namelen, &physmem, &len, NULL, 0) != 0)
224 		err(EX_OSERR, "can't get memory size");
225 	if (ioctl(fd, DIOCGMEDIASIZE, &mediasize) != 0)
226 		err(EX_OSERR, "%s: can't get size", fn);
227 	if ((uintmax_t)mediasize < (uintmax_t)physmem)
228 		errx(EX_IOERR, "%s is smaller than physical memory", fn);
229 }
230 
231 #ifdef HAVE_CRYPTO
232 static void
233 _genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
234 {
235 	FILE *fp;
236 	RSA *pubkey;
237 
238 	assert(pubkeyfile != NULL);
239 	assert(kdap != NULL);
240 
241 	fp = NULL;
242 	pubkey = NULL;
243 
244 	fp = fopen(pubkeyfile, "r");
245 	if (fp == NULL)
246 		err(1, "Unable to open %s", pubkeyfile);
247 
248 	/*
249 	 * Obsolescent OpenSSL only knows about /dev/random, and needs to
250 	 * pre-seed before entering cap mode.  For whatever reason,
251 	 * RSA_pub_encrypt uses the internal PRNG.
252 	 */
253 #if OPENSSL_VERSION_NUMBER < 0x10100000L
254 	{
255 		unsigned char c[1];
256 		RAND_bytes(c, 1);
257 	}
258 #endif
259 
260 	if (caph_enter() < 0)
261 		err(1, "Unable to enter capability mode");
262 
263 	pubkey = RSA_new();
264 	if (pubkey == NULL) {
265 		errx(1, "Unable to allocate an RSA structure: %s",
266 		    ERR_error_string(ERR_get_error(), NULL));
267 	}
268 
269 	pubkey = PEM_read_RSA_PUBKEY(fp, &pubkey, NULL, NULL);
270 	fclose(fp);
271 	fp = NULL;
272 	if (pubkey == NULL)
273 		errx(1, "Unable to read data from %s: %s", pubkeyfile,
274 		    ERR_error_string(ERR_get_error(), NULL));
275 
276 	/*
277 	 * RSA keys under ~1024 bits are trivially factorable (2018).  OpenSSL
278 	 * provides an API for RSA keys to estimate the symmetric-cipher
279 	 * "equivalent" bits of security (defined in NIST SP800-57), which as
280 	 * of this writing equates a 2048-bit RSA key to 112 symmetric cipher
281 	 * bits.
282 	 *
283 	 * Use this API as a seatbelt to avoid suggesting to users that their
284 	 * privacy is protected by encryption when the key size is insufficient
285 	 * to prevent compromise via factoring.
286 	 *
287 	 * Future work: Sanity check for weak 'e', and sanity check for absence
288 	 * of 'd' (i.e., the supplied key is a public key rather than a full
289 	 * keypair).
290 	 */
291 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
292 	if (RSA_security_bits(pubkey) < 112)
293 #else
294 	if (RSA_size(pubkey) * 8 < 2048)
295 #endif
296 		errx(1, "Small RSA keys (you provided: %db) can be "
297 		    "factored cheaply.  Please generate a larger key.",
298 		    RSA_size(pubkey) * 8);
299 
300 	kdap->kda_encryptedkeysize = RSA_size(pubkey);
301 	if (kdap->kda_encryptedkeysize > KERNELDUMP_ENCKEY_MAX_SIZE) {
302 		errx(1, "Public key has to be at most %db long.",
303 		    8 * KERNELDUMP_ENCKEY_MAX_SIZE);
304 	}
305 
306 	kdap->kda_encryptedkey = calloc(1, kdap->kda_encryptedkeysize);
307 	if (kdap->kda_encryptedkey == NULL)
308 		err(1, "Unable to allocate encrypted key");
309 
310 	/*
311 	 * If no cipher was specified, choose a reasonable default.
312 	 */
313 	if (kdap->kda_encryption == KERNELDUMP_ENC_NONE)
314 		kdap->kda_encryption = KERNELDUMP_ENC_CHACHA20;
315 	else if (kdap->kda_encryption == KERNELDUMP_ENC_AES_256_CBC &&
316 	    kdap->kda_compression != KERNELDUMP_COMP_NONE)
317 		errx(EX_USAGE, "Unpadded AES256-CBC mode cannot be used "
318 		    "with compression.");
319 
320 	arc4random_buf(kdap->kda_key, sizeof(kdap->kda_key));
321 	if (RSA_public_encrypt(sizeof(kdap->kda_key), kdap->kda_key,
322 	    kdap->kda_encryptedkey, pubkey,
323 	    RSA_PKCS1_OAEP_PADDING) != (int)kdap->kda_encryptedkeysize) {
324 		errx(1, "Unable to encrypt the one-time key: %s",
325 		    ERR_error_string(ERR_get_error(), NULL));
326 	}
327 	RSA_free(pubkey);
328 }
329 
330 /*
331  * Run genkey() in a child so it can use capability mode without affecting
332  * the rest of the runtime.
333  */
334 static void
335 genkey(const char *pubkeyfile, struct diocskerneldump_arg *kdap)
336 {
337 	pid_t pid;
338 	int error, filedes[2], status;
339 	ssize_t bytes;
340 
341 	if (pipe2(filedes, O_CLOEXEC) != 0)
342 		err(1, "pipe");
343 	pid = fork();
344 	switch (pid) {
345 	case -1:
346 		err(1, "fork");
347 		break;
348 	case 0:
349 		close(filedes[0]);
350 		_genkey(pubkeyfile, kdap);
351 		/* Write the new kdap back to the parent. */
352 		bytes = write(filedes[1], kdap, sizeof(*kdap));
353 		if (bytes != sizeof(*kdap))
354 			err(1, "genkey pipe write");
355 		bytes = write(filedes[1], kdap->kda_encryptedkey,
356 		    kdap->kda_encryptedkeysize);
357 		if (bytes != (ssize_t)kdap->kda_encryptedkeysize)
358 			err(1, "genkey pipe write kda_encryptedkey");
359 		_exit(0);
360 	}
361 	close(filedes[1]);
362 	/* Read in the child's genkey() result into kdap. */
363 	bytes = read(filedes[0], kdap, sizeof(*kdap));
364 	if (bytes != sizeof(*kdap))
365 		errx(1, "genkey pipe read");
366 	if (kdap->kda_encryptedkeysize > KERNELDUMP_ENCKEY_MAX_SIZE)
367 		errx(1, "Public key has to be at most %db long.",
368 		    8 * KERNELDUMP_ENCKEY_MAX_SIZE);
369 	kdap->kda_encryptedkey = calloc(1, kdap->kda_encryptedkeysize);
370 	if (kdap->kda_encryptedkey == NULL)
371 		err(1, "Unable to allocate encrypted key");
372 	bytes = read(filedes[0], kdap->kda_encryptedkey,
373 	    kdap->kda_encryptedkeysize);
374 	if (bytes != (ssize_t)kdap->kda_encryptedkeysize)
375 		errx(1, "genkey pipe read kda_encryptedkey");
376 	error = waitpid(pid, &status, WEXITED);
377 	if (error == -1)
378 		err(1, "waitpid");
379 	if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
380 		errx(1, "genkey child exited with status %d",
381 		    WEXITSTATUS(status));
382 	else if (WIFSIGNALED(status))
383 		errx(1, "genkey child exited with signal %d",
384 		    WTERMSIG(status));
385 	close(filedes[0]);
386 }
387 #endif
388 
389 static void
390 listdumpdev(void)
391 {
392 	static char ip[200];
393 
394 	char dumpdev[PATH_MAX];
395 	struct diocskerneldump_arg ndconf;
396 	size_t len;
397 	const char *sysctlname = "kern.shutdown.dumpdevname";
398 	int fd;
399 
400 	len = sizeof(dumpdev);
401 	if (sysctlbyname(sysctlname, &dumpdev, &len, NULL, 0) != 0) {
402 		if (errno == ENOMEM) {
403 			err(EX_OSERR, "Kernel returned too large of a buffer for '%s'\n",
404 				sysctlname);
405 		} else {
406 			err(EX_OSERR, "Sysctl get '%s'\n", sysctlname);
407 		}
408 	}
409 	if (strlen(dumpdev) == 0)
410 		(void)strlcpy(dumpdev, _PATH_DEVNULL, sizeof(dumpdev));
411 
412 	if (verbose) {
413 		char *ctx, *dd;
414 		unsigned idx;
415 
416 		printf("kernel dumps on priority: device\n");
417 		idx = 0;
418 		ctx = dumpdev;
419 		while ((dd = strsep(&ctx, ",")) != NULL)
420 			printf("%u: %s\n", idx++, dd);
421 	} else
422 		printf("%s\n", dumpdev);
423 
424 	/* If netdump is enabled, print the configuration parameters. */
425 	if (verbose) {
426 		fd = open(_PATH_NETDUMP, O_RDONLY);
427 		if (fd < 0) {
428 			if (errno != ENOENT)
429 				err(EX_OSERR, "opening %s", _PATH_NETDUMP);
430 			return;
431 		}
432 		if (ioctl(fd, DIOCGKERNELDUMP, &ndconf) != 0) {
433 			if (errno != ENXIO)
434 				err(EX_OSERR, "ioctl(DIOCGKERNELDUMP)");
435 			(void)close(fd);
436 			return;
437 		}
438 
439 		printf("server address: %s\n",
440 		    inet_ntop(ndconf.kda_af, &ndconf.kda_server, ip,
441 			sizeof(ip)));
442 		printf("client address: %s\n",
443 		    inet_ntop(ndconf.kda_af, &ndconf.kda_client, ip,
444 			sizeof(ip)));
445 		printf("gateway address: %s\n",
446 		    inet_ntop(ndconf.kda_af, &ndconf.kda_gateway, ip,
447 			sizeof(ip)));
448 		(void)close(fd);
449 	}
450 }
451 
452 static int
453 opendumpdev(const char *arg, char *dumpdev)
454 {
455 	int fd, i;
456 
457 	if (strncmp(arg, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
458 		strlcpy(dumpdev, arg, PATH_MAX);
459 	else {
460 		i = snprintf(dumpdev, PATH_MAX, "%s%s", _PATH_DEV, arg);
461 		if (i < 0)
462 			err(EX_OSERR, "%s", arg);
463 		if (i >= PATH_MAX)
464 			errc(EX_DATAERR, EINVAL, "%s", arg);
465 	}
466 
467 	fd = open(dumpdev, O_RDONLY);
468 	if (fd < 0)
469 		err(EX_OSFILE, "%s", dumpdev);
470 	return (fd);
471 }
472 
473 int
474 main(int argc, char *argv[])
475 {
476 	char dumpdev[PATH_MAX];
477 	struct diocskerneldump_arg ndconf, *kdap;
478 	struct addrinfo hints, *res;
479 	const char *dev, *pubkeyfile, *server, *client, *gateway;
480 	int ch, error, fd, cipher;
481 	bool gzip, list, netdump, zstd, insert, rflag;
482 	uint8_t ins_idx;
483 
484 	gzip = list = netdump = zstd = insert = rflag = false;
485 	kdap = NULL;
486 	pubkeyfile = NULL;
487 	server = client = gateway = NULL;
488 	ins_idx = KDA_APPEND;
489 	cipher = KERNELDUMP_ENC_NONE;
490 
491 	while ((ch = getopt(argc, argv, "C:c:g:i:k:lrs:vZz")) != -1)
492 		switch ((char)ch) {
493 		case 'C':
494 			if (strcasecmp(optarg, "chacha") == 0 ||
495 			    strcasecmp(optarg, "chacha20") == 0)
496 				cipher = KERNELDUMP_ENC_CHACHA20;
497 			else if (strcasecmp(optarg, "aes-cbc") == 0 ||
498 			    strcasecmp(optarg, "aes256-cbc") == 0)
499 				cipher = KERNELDUMP_ENC_AES_256_CBC;
500 			else
501 				errx(EX_USAGE, "Unrecognized cipher algorithm "
502 				    "'%s'", optarg);
503 			break;
504 		case 'c':
505 			client = optarg;
506 			break;
507 		case 'g':
508 			gateway = optarg;
509 			break;
510 		case 'i':
511 			{
512 			int i;
513 
514 			i = atoi(optarg);
515 			if (i < 0 || i >= KDA_APPEND - 1)
516 				errx(EX_USAGE,
517 				    "-i index must be between zero and %d.",
518 				    (int)KDA_APPEND - 2);
519 			insert = true;
520 			ins_idx = i;
521 			}
522 			break;
523 		case 'k':
524 			pubkeyfile = optarg;
525 			break;
526 		case 'l':
527 			list = true;
528 			break;
529 		case 'r':
530 			rflag = true;
531 			break;
532 		case 's':
533 			server = optarg;
534 			break;
535 		case 'v':
536 			verbose = 1;
537 			break;
538 		case 'Z':
539 			zstd = true;
540 			break;
541 		case 'z':
542 			gzip = true;
543 			break;
544 		default:
545 			usage();
546 		}
547 
548 	if (gzip && zstd)
549 		errx(EX_USAGE, "The -z and -Z options are mutually exclusive.");
550 
551 	if (insert && rflag)
552 		errx(EX_USAGE, "The -i and -r options are mutually exclusive.");
553 
554 	argc -= optind;
555 	argv += optind;
556 
557 	if (list) {
558 		listdumpdev();
559 		exit(EX_OK);
560 	}
561 
562 	if (argc != 1)
563 		usage();
564 
565 #ifdef HAVE_CRYPTO
566 	if (cipher != KERNELDUMP_ENC_NONE && pubkeyfile == NULL) {
567 		errx(EX_USAGE, "-C option requires a public key file.");
568 	} else if (pubkeyfile != NULL) {
569 #if OPENSSL_VERSION_NUMBER < 0x10100000L
570 		ERR_load_crypto_strings();
571 #else
572 		if (!OPENSSL_init_crypto(0, NULL))
573 			errx(EX_UNAVAILABLE, "Unable to initialize OpenSSL");
574 #endif
575 	}
576 #else
577 	if (pubkeyfile != NULL)
578 		errx(EX_UNAVAILABLE,"Unable to use the public key."
579 				    " Recompile dumpon with OpenSSL support.");
580 #endif
581 
582 	if (server != NULL && client != NULL) {
583 		dev = _PATH_NETDUMP;
584 		netdump = true;
585 	} else if (server == NULL && client == NULL && argc > 0) {
586 		if (strcmp(argv[0], "off") == 0) {
587 			rflag = true;
588 			dev = _PATH_DEVNULL;
589 		} else
590 			dev = argv[0];
591 		netdump = false;
592 
593 		if (strcmp(dev, _PATH_DEVNULL) == 0) {
594 			/*
595 			 * Netdump has its own configuration tracking that
596 			 * is not removed when using /dev/null.
597 			 */
598 			fd = open(_PATH_NETDUMP, O_RDONLY);
599 			if (fd != -1) {
600 				bzero(&ndconf, sizeof(ndconf));
601 				ndconf.kda_index = KDA_REMOVE_ALL;
602 				ndconf.kda_af = AF_INET;
603 				error = ioctl(fd, DIOCSKERNELDUMP, &ndconf);
604 				if (error != 0)
605 					err(1, "ioctl(%s, DIOCSKERNELDUMP)",
606 					    _PATH_NETDUMP);
607 				close(fd);
608 			}
609 		}
610 	} else
611 		usage();
612 
613 	fd = opendumpdev(dev, dumpdev);
614 	if (!netdump && !gzip && !zstd && !rflag)
615 		check_size(fd, dumpdev);
616 
617 	kdap = &ndconf;
618 	bzero(kdap, sizeof(*kdap));
619 
620 	if (rflag)
621 		kdap->kda_index = KDA_REMOVE;
622 	else
623 		kdap->kda_index = ins_idx;
624 
625 	kdap->kda_compression = KERNELDUMP_COMP_NONE;
626 	if (zstd)
627 		kdap->kda_compression = KERNELDUMP_COMP_ZSTD;
628 	else if (gzip)
629 		kdap->kda_compression = KERNELDUMP_COMP_GZIP;
630 
631 	if (netdump) {
632 		memset(&hints, 0, sizeof(hints));
633 		hints.ai_family = AF_INET;
634 		hints.ai_protocol = IPPROTO_UDP;
635 		res = NULL;
636 		error = getaddrinfo(server, NULL, &hints, &res);
637 		if (error != 0) {
638 			if (error == EAI_SYSTEM)
639 				err(EX_OSERR, "%s", gai_strerror(error));
640 			errx(EX_NOHOST, "%s", gai_strerror(error));
641 		}
642 		server = inet_ntoa(
643 		    ((struct sockaddr_in *)(void *)res->ai_addr)->sin_addr);
644 		freeaddrinfo(res);
645 
646 		if (strlcpy(ndconf.kda_iface, argv[0],
647 		    sizeof(ndconf.kda_iface)) >= sizeof(ndconf.kda_iface))
648 			errx(EX_USAGE, "invalid interface name '%s'", argv[0]);
649 		if (inet_aton(server, &ndconf.kda_server.in4) == 0)
650 			errx(EX_USAGE, "invalid server address '%s'", server);
651 		if (inet_aton(client, &ndconf.kda_client.in4) == 0)
652 			errx(EX_USAGE, "invalid client address '%s'", client);
653 
654 		if (gateway == NULL) {
655 			gateway = find_gateway(argv[0]);
656 			if (gateway == NULL) {
657 				if (verbose)
658 					printf(
659 				    "failed to look up gateway for %s\n",
660 					    server);
661 				gateway = server;
662 			}
663 		}
664 		if (inet_aton(gateway, &ndconf.kda_gateway.in4) == 0)
665 			errx(EX_USAGE, "invalid gateway address '%s'", gateway);
666 		ndconf.kda_af = AF_INET;
667 	}
668 
669 #ifdef HAVE_CRYPTO
670 	if (pubkeyfile != NULL) {
671 		kdap->kda_encryption = cipher;
672 		genkey(pubkeyfile, kdap);
673 	}
674 #endif
675 	error = ioctl(fd, DIOCSKERNELDUMP, kdap);
676 	if (error != 0)
677 		error = errno;
678 	if (error == EINVAL && (gzip || zstd)) {
679 		/* Retry without compression in case kernel lacks support. */
680 		kdap->kda_compression = KERNELDUMP_COMP_NONE;
681 		error = ioctl(fd, DIOCSKERNELDUMP, kdap);
682 		if (error == 0)
683 			warnx("Compression disabled; kernel may lack gzip or zstd support.");
684 		else
685 			error = errno;
686 	}
687 	/* Emit a warning if the user configured a downed interface. */
688 	if (error == 0 && netdump)
689 		check_link_status(kdap->kda_iface);
690 	explicit_bzero(kdap->kda_encryptedkey, kdap->kda_encryptedkeysize);
691 	free(kdap->kda_encryptedkey);
692 	explicit_bzero(kdap, sizeof(*kdap));
693 	if (error != 0) {
694 		if (netdump) {
695 			/*
696 			 * Be slightly less user-hostile for some common
697 			 * errors, especially as users don't have any great
698 			 * discoverability into which NICs support netdump.
699 			 */
700 			if (error == ENODEV)
701 				errx(EX_OSERR, "Unable to configure netdump "
702 				    "because the interface driver does not yet "
703 				    "support netdump.");
704 		}
705 		errc(EX_OSERR, error, "ioctl(DIOCSKERNELDUMP)");
706 	}
707 
708 	if (verbose)
709 		listdumpdev();
710 
711 	exit(EX_OK);
712 }
713