1/* $OpenBSD: hostfile.c,v 1.73 2018/07/16 03:09:13 djm Exp $ */
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 *                    All rights reserved
6 * Functions for manipulating the known hosts files.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose.  Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 *
14 *
15 * Copyright (c) 1999, 2000 Markus Friedl.  All rights reserved.
16 * Copyright (c) 1999 Niels Provos.  All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 *    notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 *    notice, this list of conditions and the following disclaimer in the
25 *    documentation and/or other materials provided with the distribution.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include "includes.h"
40
41#include <sys/types.h>
42#include <sys/stat.h>
43
44#include <netinet/in.h>
45
46#include <errno.h>
47#include <resolv.h>
48#include <stdarg.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52#include <stdarg.h>
53#include <unistd.h>
54
55#include "xmalloc.h"
56#include "match.h"
57#include "sshkey.h"
58#include "hostfile.h"
59#include "log.h"
60#include "misc.h"
61#include "ssherr.h"
62#include "digest.h"
63#include "hmac.h"
64
65struct hostkeys {
66	struct hostkey_entry *entries;
67	u_int num_entries;
68};
69
70/* XXX hmac is too easy to dictionary attack; use bcrypt? */
71
72static int
73extract_salt(const char *s, u_int l, u_char *salt, size_t salt_len)
74{
75	char *p, *b64salt;
76	u_int b64len;
77	int ret;
78
79	if (l < sizeof(HASH_MAGIC) - 1) {
80		debug2("extract_salt: string too short");
81		return (-1);
82	}
83	if (strncmp(s, HASH_MAGIC, sizeof(HASH_MAGIC) - 1) != 0) {
84		debug2("extract_salt: invalid magic identifier");
85		return (-1);
86	}
87	s += sizeof(HASH_MAGIC) - 1;
88	l -= sizeof(HASH_MAGIC) - 1;
89	if ((p = memchr(s, HASH_DELIM, l)) == NULL) {
90		debug2("extract_salt: missing salt termination character");
91		return (-1);
92	}
93
94	b64len = p - s;
95	/* Sanity check */
96	if (b64len == 0 || b64len > 1024) {
97		debug2("extract_salt: bad encoded salt length %u", b64len);
98		return (-1);
99	}
100	b64salt = xmalloc(1 + b64len);
101	memcpy(b64salt, s, b64len);
102	b64salt[b64len] = '\0';
103
104	ret = __b64_pton(b64salt, salt, salt_len);
105	free(b64salt);
106	if (ret == -1) {
107		debug2("extract_salt: salt decode error");
108		return (-1);
109	}
110	if (ret != (int)ssh_hmac_bytes(SSH_DIGEST_SHA1)) {
111		debug2("extract_salt: expected salt len %zd, got %d",
112		    ssh_hmac_bytes(SSH_DIGEST_SHA1), ret);
113		return (-1);
114	}
115
116	return (0);
117}
118
119char *
120host_hash(const char *host, const char *name_from_hostfile, u_int src_len)
121{
122	struct ssh_hmac_ctx *ctx;
123	u_char salt[256], result[256];
124	char uu_salt[512], uu_result[512];
125	static char encoded[1024];
126	u_int len;
127
128	len = ssh_digest_bytes(SSH_DIGEST_SHA1);
129
130	if (name_from_hostfile == NULL) {
131		/* Create new salt */
132		arc4random_buf(salt, len);
133	} else {
134		/* Extract salt from known host entry */
135		if (extract_salt(name_from_hostfile, src_len, salt,
136		    sizeof(salt)) == -1)
137			return (NULL);
138	}
139
140	if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL ||
141	    ssh_hmac_init(ctx, salt, len) < 0 ||
142	    ssh_hmac_update(ctx, host, strlen(host)) < 0 ||
143	    ssh_hmac_final(ctx, result, sizeof(result)))
144		fatal("%s: ssh_hmac failed", __func__);
145	ssh_hmac_free(ctx);
146
147	if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 ||
148	    __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1)
149		fatal("%s: __b64_ntop failed", __func__);
150
151	snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt,
152	    HASH_DELIM, uu_result);
153
154	return (encoded);
155}
156
157/*
158 * Parses an RSA (number of bits, e, n) or DSA key from a string.  Moves the
159 * pointer over the key.  Skips any whitespace at the beginning and at end.
160 */
161
162int
163hostfile_read_key(char **cpp, u_int *bitsp, struct sshkey *ret)
164{
165	char *cp;
166	int r;
167
168	/* Skip leading whitespace. */
169	for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
170		;
171
172	if ((r = sshkey_read(ret, &cp)) != 0)
173		return 0;
174
175	/* Skip trailing whitespace. */
176	for (; *cp == ' ' || *cp == '\t'; cp++)
177		;
178
179	/* Return results. */
180	*cpp = cp;
181	if (bitsp != NULL)
182		*bitsp = sshkey_size(ret);
183	return 1;
184}
185
186static HostkeyMarker
187check_markers(char **cpp)
188{
189	char marker[32], *sp, *cp = *cpp;
190	int ret = MRK_NONE;
191
192	while (*cp == '@') {
193		/* Only one marker is allowed */
194		if (ret != MRK_NONE)
195			return MRK_ERROR;
196		/* Markers are terminated by whitespace */
197		if ((sp = strchr(cp, ' ')) == NULL &&
198		    (sp = strchr(cp, '\t')) == NULL)
199			return MRK_ERROR;
200		/* Extract marker for comparison */
201		if (sp <= cp + 1 || sp >= cp + sizeof(marker))
202			return MRK_ERROR;
203		memcpy(marker, cp, sp - cp);
204		marker[sp - cp] = '\0';
205		if (strcmp(marker, CA_MARKER) == 0)
206			ret = MRK_CA;
207		else if (strcmp(marker, REVOKE_MARKER) == 0)
208			ret = MRK_REVOKE;
209		else
210			return MRK_ERROR;
211
212		/* Skip past marker and any whitespace that follows it */
213		cp = sp;
214		for (; *cp == ' ' || *cp == '\t'; cp++)
215			;
216	}
217	*cpp = cp;
218	return ret;
219}
220
221struct hostkeys *
222init_hostkeys(void)
223{
224	struct hostkeys *ret = xcalloc(1, sizeof(*ret));
225
226	ret->entries = NULL;
227	return ret;
228}
229
230struct load_callback_ctx {
231	const char *host;
232	u_long num_loaded;
233	struct hostkeys *hostkeys;
234};
235
236static int
237record_hostkey(struct hostkey_foreach_line *l, void *_ctx)
238{
239	struct load_callback_ctx *ctx = (struct load_callback_ctx *)_ctx;
240	struct hostkeys *hostkeys = ctx->hostkeys;
241	struct hostkey_entry *tmp;
242
243	if (l->status == HKF_STATUS_INVALID) {
244		/* XXX make this verbose() in the future */
245		debug("%s:%ld: parse error in hostkeys file",
246		    l->path, l->linenum);
247		return 0;
248	}
249
250	debug3("%s: found %skey type %s in file %s:%lu", __func__,
251	    l->marker == MRK_NONE ? "" :
252	    (l->marker == MRK_CA ? "ca " : "revoked "),
253	    sshkey_type(l->key), l->path, l->linenum);
254	if ((tmp = recallocarray(hostkeys->entries, hostkeys->num_entries,
255	    hostkeys->num_entries + 1, sizeof(*hostkeys->entries))) == NULL)
256		return SSH_ERR_ALLOC_FAIL;
257	hostkeys->entries = tmp;
258	hostkeys->entries[hostkeys->num_entries].host = xstrdup(ctx->host);
259	hostkeys->entries[hostkeys->num_entries].file = xstrdup(l->path);
260	hostkeys->entries[hostkeys->num_entries].line = l->linenum;
261	hostkeys->entries[hostkeys->num_entries].key = l->key;
262	l->key = NULL; /* steal it */
263	hostkeys->entries[hostkeys->num_entries].marker = l->marker;
264	hostkeys->num_entries++;
265	ctx->num_loaded++;
266
267	return 0;
268}
269
270void
271load_hostkeys(struct hostkeys *hostkeys, const char *host, const char *path)
272{
273	int r;
274	struct load_callback_ctx ctx;
275
276	ctx.host = host;
277	ctx.num_loaded = 0;
278	ctx.hostkeys = hostkeys;
279
280	if ((r = hostkeys_foreach(path, record_hostkey, &ctx, host, NULL,
281	    HKF_WANT_MATCH|HKF_WANT_PARSE_KEY)) != 0) {
282		if (r != SSH_ERR_SYSTEM_ERROR && errno != ENOENT)
283			debug("%s: hostkeys_foreach failed for %s: %s",
284			    __func__, path, ssh_err(r));
285	}
286	if (ctx.num_loaded != 0)
287		debug3("%s: loaded %lu keys from %s", __func__,
288		    ctx.num_loaded, host);
289}
290
291void
292free_hostkeys(struct hostkeys *hostkeys)
293{
294	u_int i;
295
296	for (i = 0; i < hostkeys->num_entries; i++) {
297		free(hostkeys->entries[i].host);
298		free(hostkeys->entries[i].file);
299		sshkey_free(hostkeys->entries[i].key);
300		explicit_bzero(hostkeys->entries + i, sizeof(*hostkeys->entries));
301	}
302	free(hostkeys->entries);
303	explicit_bzero(hostkeys, sizeof(*hostkeys));
304	free(hostkeys);
305}
306
307static int
308check_key_not_revoked(struct hostkeys *hostkeys, struct sshkey *k)
309{
310	int is_cert = sshkey_is_cert(k);
311	u_int i;
312
313	for (i = 0; i < hostkeys->num_entries; i++) {
314		if (hostkeys->entries[i].marker != MRK_REVOKE)
315			continue;
316		if (sshkey_equal_public(k, hostkeys->entries[i].key))
317			return -1;
318		if (is_cert &&
319		    sshkey_equal_public(k->cert->signature_key,
320		    hostkeys->entries[i].key))
321			return -1;
322	}
323	return 0;
324}
325
326/*
327 * Match keys against a specified key, or look one up by key type.
328 *
329 * If looking for a keytype (key == NULL) and one is found then return
330 * HOST_FOUND, otherwise HOST_NEW.
331 *
332 * If looking for a key (key != NULL):
333 *  1. If the key is a cert and a matching CA is found, return HOST_OK
334 *  2. If the key is not a cert and a matching key is found, return HOST_OK
335 *  3. If no key matches but a key with a different type is found, then
336 *     return HOST_CHANGED
337 *  4. If no matching keys are found, then return HOST_NEW.
338 *
339 * Finally, check any found key is not revoked.
340 */
341static HostStatus
342check_hostkeys_by_key_or_type(struct hostkeys *hostkeys,
343    struct sshkey *k, int keytype, const struct hostkey_entry **found)
344{
345	u_int i;
346	HostStatus end_return = HOST_NEW;
347	int want_cert = sshkey_is_cert(k);
348	HostkeyMarker want_marker = want_cert ? MRK_CA : MRK_NONE;
349
350	if (found != NULL)
351		*found = NULL;
352
353	for (i = 0; i < hostkeys->num_entries; i++) {
354		if (hostkeys->entries[i].marker != want_marker)
355			continue;
356		if (k == NULL) {
357			if (hostkeys->entries[i].key->type != keytype)
358				continue;
359			end_return = HOST_FOUND;
360			if (found != NULL)
361				*found = hostkeys->entries + i;
362			k = hostkeys->entries[i].key;
363			break;
364		}
365		if (want_cert) {
366			if (sshkey_equal_public(k->cert->signature_key,
367			    hostkeys->entries[i].key)) {
368				/* A matching CA exists */
369				end_return = HOST_OK;
370				if (found != NULL)
371					*found = hostkeys->entries + i;
372				break;
373			}
374		} else {
375			if (sshkey_equal(k, hostkeys->entries[i].key)) {
376				end_return = HOST_OK;
377				if (found != NULL)
378					*found = hostkeys->entries + i;
379				break;
380			}
381			/* A non-maching key exists */
382			end_return = HOST_CHANGED;
383			if (found != NULL)
384				*found = hostkeys->entries + i;
385		}
386	}
387	if (check_key_not_revoked(hostkeys, k) != 0) {
388		end_return = HOST_REVOKED;
389		if (found != NULL)
390			*found = NULL;
391	}
392	return end_return;
393}
394
395HostStatus
396check_key_in_hostkeys(struct hostkeys *hostkeys, struct sshkey *key,
397    const struct hostkey_entry **found)
398{
399	if (key == NULL)
400		fatal("no key to look up");
401	return check_hostkeys_by_key_or_type(hostkeys, key, 0, found);
402}
403
404int
405lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype,
406    const struct hostkey_entry **found)
407{
408	return (check_hostkeys_by_key_or_type(hostkeys, NULL, keytype,
409	    found) == HOST_FOUND);
410}
411
412static int
413write_host_entry(FILE *f, const char *host, const char *ip,
414    const struct sshkey *key, int store_hash)
415{
416	int r, success = 0;
417	char *hashed_host = NULL, *lhost;
418
419	lhost = xstrdup(host);
420	lowercase(lhost);
421
422	if (store_hash) {
423		if ((hashed_host = host_hash(lhost, NULL, 0)) == NULL) {
424			error("%s: host_hash failed", __func__);
425			free(lhost);
426			return 0;
427		}
428		fprintf(f, "%s ", hashed_host);
429	} else if (ip != NULL)
430		fprintf(f, "%s,%s ", lhost, ip);
431	else {
432		fprintf(f, "%s ", lhost);
433	}
434	free(lhost);
435	if ((r = sshkey_write(key, f)) == 0)
436		success = 1;
437	else
438		error("%s: sshkey_write failed: %s", __func__, ssh_err(r));
439	fputc('\n', f);
440	return success;
441}
442
443/*
444 * Appends an entry to the host file.  Returns false if the entry could not
445 * be appended.
446 */
447int
448add_host_to_hostfile(const char *filename, const char *host,
449    const struct sshkey *key, int store_hash)
450{
451	FILE *f;
452	int success;
453
454	if (key == NULL)
455		return 1;	/* XXX ? */
456	f = fopen(filename, "a");
457	if (!f)
458		return 0;
459	success = write_host_entry(f, host, NULL, key, store_hash);
460	fclose(f);
461	return success;
462}
463
464struct host_delete_ctx {
465	FILE *out;
466	int quiet;
467	const char *host;
468	int *skip_keys; /* XXX split for host/ip? might want to ensure both */
469	struct sshkey * const *keys;
470	size_t nkeys;
471	int modified;
472};
473
474static int
475host_delete(struct hostkey_foreach_line *l, void *_ctx)
476{
477	struct host_delete_ctx *ctx = (struct host_delete_ctx *)_ctx;
478	int loglevel = ctx->quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
479	size_t i;
480
481	if (l->status == HKF_STATUS_MATCHED) {
482		if (l->marker != MRK_NONE) {
483			/* Don't remove CA and revocation lines */
484			fprintf(ctx->out, "%s\n", l->line);
485			return 0;
486		}
487
488		/*
489		 * If this line contains one of the keys that we will be
490		 * adding later, then don't change it and mark the key for
491		 * skipping.
492		 */
493		for (i = 0; i < ctx->nkeys; i++) {
494			if (sshkey_equal(ctx->keys[i], l->key)) {
495				ctx->skip_keys[i] = 1;
496				fprintf(ctx->out, "%s\n", l->line);
497				debug3("%s: %s key already at %s:%ld", __func__,
498				    sshkey_type(l->key), l->path, l->linenum);
499				return 0;
500			}
501		}
502
503		/*
504		 * Hostname matches and has no CA/revoke marker, delete it
505		 * by *not* writing the line to ctx->out.
506		 */
507		do_log2(loglevel, "%s%s%s:%ld: Removed %s key for host %s",
508		    ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
509		    l->path, l->linenum, sshkey_type(l->key), ctx->host);
510		ctx->modified = 1;
511		return 0;
512	}
513	/* Retain non-matching hosts and invalid lines when deleting */
514	if (l->status == HKF_STATUS_INVALID) {
515		do_log2(loglevel, "%s%s%s:%ld: invalid known_hosts entry",
516		    ctx->quiet ? __func__ : "", ctx->quiet ? ": " : "",
517		    l->path, l->linenum);
518	}
519	fprintf(ctx->out, "%s\n", l->line);
520	return 0;
521}
522
523int
524hostfile_replace_entries(const char *filename, const char *host, const char *ip,
525    struct sshkey **keys, size_t nkeys, int store_hash, int quiet, int hash_alg)
526{
527	int r, fd, oerrno = 0;
528	int loglevel = quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_VERBOSE;
529	struct host_delete_ctx ctx;
530	char *fp, *temp = NULL, *back = NULL;
531	mode_t omask;
532	size_t i;
533
534	omask = umask(077);
535
536	memset(&ctx, 0, sizeof(ctx));
537	ctx.host = host;
538	ctx.quiet = quiet;
539	if ((ctx.skip_keys = calloc(nkeys, sizeof(*ctx.skip_keys))) == NULL)
540		return SSH_ERR_ALLOC_FAIL;
541	ctx.keys = keys;
542	ctx.nkeys = nkeys;
543	ctx.modified = 0;
544
545	/*
546	 * Prepare temporary file for in-place deletion.
547	 */
548	if ((r = asprintf(&temp, "%s.XXXXXXXXXXX", filename)) < 0 ||
549	    (r = asprintf(&back, "%s.old", filename)) < 0) {
550		r = SSH_ERR_ALLOC_FAIL;
551		goto fail;
552	}
553
554	if ((fd = mkstemp(temp)) == -1) {
555		oerrno = errno;
556		error("%s: mkstemp: %s", __func__, strerror(oerrno));
557		r = SSH_ERR_SYSTEM_ERROR;
558		goto fail;
559	}
560	if ((ctx.out = fdopen(fd, "w")) == NULL) {
561		oerrno = errno;
562		close(fd);
563		error("%s: fdopen: %s", __func__, strerror(oerrno));
564		r = SSH_ERR_SYSTEM_ERROR;
565		goto fail;
566	}
567
568	/* Remove all entries for the specified host from the file */
569	if ((r = hostkeys_foreach(filename, host_delete, &ctx, host, ip,
570	    HKF_WANT_PARSE_KEY)) != 0) {
571		error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
572		goto fail;
573	}
574
575	/* Add the requested keys */
576	for (i = 0; i < nkeys; i++) {
577		if (ctx.skip_keys[i])
578			continue;
579		if ((fp = sshkey_fingerprint(keys[i], hash_alg,
580		    SSH_FP_DEFAULT)) == NULL) {
581			r = SSH_ERR_ALLOC_FAIL;
582			goto fail;
583		}
584		do_log2(loglevel, "%s%sAdding new key for %s to %s: %s %s",
585		    quiet ? __func__ : "", quiet ? ": " : "", host, filename,
586		    sshkey_ssh_name(keys[i]), fp);
587		free(fp);
588		if (!write_host_entry(ctx.out, host, ip, keys[i], store_hash)) {
589			r = SSH_ERR_INTERNAL_ERROR;
590			goto fail;
591		}
592		ctx.modified = 1;
593	}
594	fclose(ctx.out);
595	ctx.out = NULL;
596
597	if (ctx.modified) {
598		/* Backup the original file and replace it with the temporary */
599		if (unlink(back) == -1 && errno != ENOENT) {
600			oerrno = errno;
601			error("%s: unlink %.100s: %s", __func__,
602			    back, strerror(errno));
603			r = SSH_ERR_SYSTEM_ERROR;
604			goto fail;
605		}
606		if (link(filename, back) == -1) {
607			oerrno = errno;
608			error("%s: link %.100s to %.100s: %s", __func__,
609			    filename, back, strerror(errno));
610			r = SSH_ERR_SYSTEM_ERROR;
611			goto fail;
612		}
613		if (rename(temp, filename) == -1) {
614			oerrno = errno;
615			error("%s: rename \"%s\" to \"%s\": %s", __func__,
616			    temp, filename, strerror(errno));
617			r = SSH_ERR_SYSTEM_ERROR;
618			goto fail;
619		}
620	} else {
621		/* No changes made; just delete the temporary file */
622		if (unlink(temp) != 0)
623			error("%s: unlink \"%s\": %s", __func__,
624			    temp, strerror(errno));
625	}
626
627	/* success */
628	r = 0;
629 fail:
630	if (temp != NULL && r != 0)
631		unlink(temp);
632	free(temp);
633	free(back);
634	if (ctx.out != NULL)
635		fclose(ctx.out);
636	free(ctx.skip_keys);
637	umask(omask);
638	if (r == SSH_ERR_SYSTEM_ERROR)
639		errno = oerrno;
640	return r;
641}
642
643static int
644match_maybe_hashed(const char *host, const char *names, int *was_hashed)
645{
646	int hashed = *names == HASH_DELIM;
647	const char *hashed_host;
648	size_t nlen = strlen(names);
649
650	if (was_hashed != NULL)
651		*was_hashed = hashed;
652	if (hashed) {
653		if ((hashed_host = host_hash(host, names, nlen)) == NULL)
654			return -1;
655		return nlen == strlen(hashed_host) &&
656		    strncmp(hashed_host, names, nlen) == 0;
657	}
658	return match_hostname(host, names) == 1;
659}
660
661int
662hostkeys_foreach(const char *path, hostkeys_foreach_fn *callback, void *ctx,
663    const char *host, const char *ip, u_int options)
664{
665	FILE *f;
666	char *line = NULL, ktype[128];
667	u_long linenum = 0;
668	char *cp, *cp2;
669	u_int kbits;
670	int hashed;
671	int s, r = 0;
672	struct hostkey_foreach_line lineinfo;
673	size_t linesize = 0, l;
674
675	memset(&lineinfo, 0, sizeof(lineinfo));
676	if (host == NULL && (options & HKF_WANT_MATCH) != 0)
677		return SSH_ERR_INVALID_ARGUMENT;
678	if ((f = fopen(path, "r")) == NULL)
679		return SSH_ERR_SYSTEM_ERROR;
680
681	debug3("%s: reading file \"%s\"", __func__, path);
682	while (getline(&line, &linesize, f) != -1) {
683		linenum++;
684		line[strcspn(line, "\n")] = '\0';
685
686		free(lineinfo.line);
687		sshkey_free(lineinfo.key);
688		memset(&lineinfo, 0, sizeof(lineinfo));
689		lineinfo.path = path;
690		lineinfo.linenum = linenum;
691		lineinfo.line = xstrdup(line);
692		lineinfo.marker = MRK_NONE;
693		lineinfo.status = HKF_STATUS_OK;
694		lineinfo.keytype = KEY_UNSPEC;
695
696		/* Skip any leading whitespace, comments and empty lines. */
697		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
698			;
699		if (!*cp || *cp == '#' || *cp == '\n') {
700			if ((options & HKF_WANT_MATCH) == 0) {
701				lineinfo.status = HKF_STATUS_COMMENT;
702				if ((r = callback(&lineinfo, ctx)) != 0)
703					break;
704			}
705			continue;
706		}
707
708		if ((lineinfo.marker = check_markers(&cp)) == MRK_ERROR) {
709			verbose("%s: invalid marker at %s:%lu",
710			    __func__, path, linenum);
711			if ((options & HKF_WANT_MATCH) == 0)
712				goto bad;
713			continue;
714		}
715
716		/* Find the end of the host name portion. */
717		for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
718			;
719		lineinfo.hosts = cp;
720		*cp2++ = '\0';
721
722		/* Check if the host name matches. */
723		if (host != NULL) {
724			if ((s = match_maybe_hashed(host, lineinfo.hosts,
725			    &hashed)) == -1) {
726				debug2("%s: %s:%ld: bad host hash \"%.32s\"",
727				    __func__, path, linenum, lineinfo.hosts);
728				goto bad;
729			}
730			if (s == 1) {
731				lineinfo.status = HKF_STATUS_MATCHED;
732				lineinfo.match |= HKF_MATCH_HOST |
733				    (hashed ? HKF_MATCH_HOST_HASHED : 0);
734			}
735			/* Try matching IP address if supplied */
736			if (ip != NULL) {
737				if ((s = match_maybe_hashed(ip, lineinfo.hosts,
738				    &hashed)) == -1) {
739					debug2("%s: %s:%ld: bad ip hash "
740					    "\"%.32s\"", __func__, path,
741					    linenum, lineinfo.hosts);
742					goto bad;
743				}
744				if (s == 1) {
745					lineinfo.status = HKF_STATUS_MATCHED;
746					lineinfo.match |= HKF_MATCH_IP |
747					    (hashed ? HKF_MATCH_IP_HASHED : 0);
748				}
749			}
750			/*
751			 * Skip this line if host matching requested and
752			 * neither host nor address matched.
753			 */
754			if ((options & HKF_WANT_MATCH) != 0 &&
755			    lineinfo.status != HKF_STATUS_MATCHED)
756				continue;
757		}
758
759		/* Got a match.  Skip host name and any following whitespace */
760		for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
761			;
762		if (*cp2 == '\0' || *cp2 == '#') {
763			debug2("%s:%ld: truncated before key type",
764			    path, linenum);
765			goto bad;
766		}
767		lineinfo.rawkey = cp = cp2;
768
769		if ((options & HKF_WANT_PARSE_KEY) != 0) {
770			/*
771			 * Extract the key from the line.  This will skip
772			 * any leading whitespace.  Ignore badly formatted
773			 * lines.
774			 */
775			if ((lineinfo.key = sshkey_new(KEY_UNSPEC)) == NULL) {
776				error("%s: sshkey_new failed", __func__);
777				r = SSH_ERR_ALLOC_FAIL;
778				break;
779			}
780			if (!hostfile_read_key(&cp, &kbits, lineinfo.key)) {
781				goto bad;
782			}
783			lineinfo.keytype = lineinfo.key->type;
784			lineinfo.comment = cp;
785		} else {
786			/* Extract and parse key type */
787			l = strcspn(lineinfo.rawkey, " \t");
788			if (l <= 1 || l >= sizeof(ktype) ||
789			    lineinfo.rawkey[l] == '\0')
790				goto bad;
791			memcpy(ktype, lineinfo.rawkey, l);
792			ktype[l] = '\0';
793			lineinfo.keytype = sshkey_type_from_name(ktype);
794
795			/*
796			 * Assume legacy RSA1 if the first component is a short
797			 * decimal number.
798			 */
799			if (lineinfo.keytype == KEY_UNSPEC && l < 8 &&
800			    strspn(ktype, "0123456789") == l)
801				goto bad;
802
803			/*
804			 * Check that something other than whitespace follows
805			 * the key type. This won't catch all corruption, but
806			 * it does catch trivial truncation.
807			 */
808			cp2 += l; /* Skip past key type */
809			for (; *cp2 == ' ' || *cp2 == '\t'; cp2++)
810				;
811			if (*cp2 == '\0' || *cp2 == '#') {
812				debug2("%s:%ld: truncated after key type",
813				    path, linenum);
814				lineinfo.keytype = KEY_UNSPEC;
815			}
816			if (lineinfo.keytype == KEY_UNSPEC) {
817 bad:
818				sshkey_free(lineinfo.key);
819				lineinfo.key = NULL;
820				lineinfo.status = HKF_STATUS_INVALID;
821				if ((r = callback(&lineinfo, ctx)) != 0)
822					break;
823				continue;
824			}
825		}
826		if ((r = callback(&lineinfo, ctx)) != 0)
827			break;
828	}
829	sshkey_free(lineinfo.key);
830	free(lineinfo.line);
831	free(line);
832	fclose(f);
833	return r;
834}
835