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