xref: /freebsd/crypto/openssh/hostfile.c (revision ca3176e7c8c53ffd5e822c8bad53fa885faf7ae0)
1511b41d2SMark Murray /*
2511b41d2SMark Murray  * Author: Tatu Ylonen <ylo@cs.hut.fi>
3511b41d2SMark Murray  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4511b41d2SMark Murray  *                    All rights reserved
5511b41d2SMark Murray  * Functions for manipulating the known hosts files.
6511b41d2SMark Murray  *
7c2d3a559SKris Kennaway  * As far as I am concerned, the code I have written for this software
8c2d3a559SKris Kennaway  * can be used freely for any purpose.  Any derived versions of this
9c2d3a559SKris Kennaway  * software must be clearly marked as such, and if the derived work is
10c2d3a559SKris Kennaway  * incompatible with the protocol description in the RFC file, it must be
11c2d3a559SKris Kennaway  * called by a name other than "ssh" or "Secure Shell".
12c2d3a559SKris Kennaway  *
13c2d3a559SKris Kennaway  *
14c2d3a559SKris Kennaway  * Copyright (c) 1999,2000 Markus Friedl.  All rights reserved.
15c2d3a559SKris Kennaway  * Copyright (c) 1999 Niels Provos.  All rights reserved.
16c2d3a559SKris Kennaway  *
17c2d3a559SKris Kennaway  * Redistribution and use in source and binary forms, with or without
18c2d3a559SKris Kennaway  * modification, are permitted provided that the following conditions
19c2d3a559SKris Kennaway  * are met:
20c2d3a559SKris Kennaway  * 1. Redistributions of source code must retain the above copyright
21c2d3a559SKris Kennaway  *    notice, this list of conditions and the following disclaimer.
22c2d3a559SKris Kennaway  * 2. Redistributions in binary form must reproduce the above copyright
23c2d3a559SKris Kennaway  *    notice, this list of conditions and the following disclaimer in the
24c2d3a559SKris Kennaway  *    documentation and/or other materials provided with the distribution.
25c2d3a559SKris Kennaway  *
26c2d3a559SKris Kennaway  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27c2d3a559SKris Kennaway  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28c2d3a559SKris Kennaway  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29c2d3a559SKris Kennaway  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30c2d3a559SKris Kennaway  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31c2d3a559SKris Kennaway  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32c2d3a559SKris Kennaway  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33c2d3a559SKris Kennaway  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34c2d3a559SKris Kennaway  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35c2d3a559SKris Kennaway  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36511b41d2SMark Murray  */
37511b41d2SMark Murray 
38511b41d2SMark Murray #include "includes.h"
39ca3176e7SBrian Feldman RCSID("$OpenBSD: hostfile.c,v 1.26 2001/04/12 19:15:24 markus Exp $");
40c2d3a559SKris Kennaway RCSID("$FreeBSD$");
41511b41d2SMark Murray 
42511b41d2SMark Murray #include "packet.h"
43a8f6863aSKris Kennaway #include "match.h"
44a8f6863aSKris Kennaway #include "key.h"
45a8f6863aSKris Kennaway #include "hostfile.h"
46ca3176e7SBrian Feldman #include "log.h"
47511b41d2SMark Murray 
48511b41d2SMark Murray /*
49a8f6863aSKris Kennaway  * Parses an RSA (number of bits, e, n) or DSA key from a string.  Moves the
50a8f6863aSKris Kennaway  * pointer over the key.  Skips any whitespace at the beginning and at end.
51511b41d2SMark Murray  */
52511b41d2SMark Murray 
53511b41d2SMark Murray int
54ca3176e7SBrian Feldman hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
55511b41d2SMark Murray {
56511b41d2SMark Murray 	char *cp;
57511b41d2SMark Murray 
58511b41d2SMark Murray 	/* Skip leading whitespace. */
59511b41d2SMark Murray 	for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
60511b41d2SMark Murray 		;
61511b41d2SMark Murray 
62ca3176e7SBrian Feldman 	if (key_read(ret, &cp) != 1)
63511b41d2SMark Murray 		return 0;
64511b41d2SMark Murray 
65511b41d2SMark Murray 	/* Skip trailing whitespace. */
66511b41d2SMark Murray 	for (; *cp == ' ' || *cp == '\t'; cp++)
67511b41d2SMark Murray 		;
68511b41d2SMark Murray 
69511b41d2SMark Murray 	/* Return results. */
70511b41d2SMark Murray 	*cpp = cp;
71ca3176e7SBrian Feldman 	*bitsp = key_size(ret);
72511b41d2SMark Murray 	return 1;
73511b41d2SMark Murray }
74511b41d2SMark Murray 
75a8f6863aSKris Kennaway int
76ca3176e7SBrian Feldman auth_rsa_read_key(char **cpp, u_int *bitsp, BIGNUM * e, BIGNUM * n)
77a8f6863aSKris Kennaway {
78ca3176e7SBrian Feldman 	Key *k = key_new(KEY_RSA1);
79a8f6863aSKris Kennaway 	int ret = hostfile_read_key(cpp, bitsp, k);
80a8f6863aSKris Kennaway 	BN_copy(e, k->rsa->e);
81a8f6863aSKris Kennaway 	BN_copy(n, k->rsa->n);
82a8f6863aSKris Kennaway 	key_free(k);
83a8f6863aSKris Kennaway 	return ret;
84a8f6863aSKris Kennaway }
85511b41d2SMark Murray 
86511b41d2SMark Murray int
87a8f6863aSKris Kennaway hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
88511b41d2SMark Murray {
89ca3176e7SBrian Feldman 	if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
90a8f6863aSKris Kennaway 		return 1;
91a8f6863aSKris Kennaway 	if (bits != BN_num_bits(key->rsa->n)) {
92e8aafc91SKris Kennaway 		log("Warning: %s, line %d: keysize mismatch for host %s: "
93a8f6863aSKris Kennaway 		    "actual %d vs. announced %d.",
94a8f6863aSKris Kennaway 		    filename, linenum, host, BN_num_bits(key->rsa->n), bits);
95e8aafc91SKris Kennaway 		log("Warning: replace %d with %d in %s, line %d.",
96a8f6863aSKris Kennaway 		    bits, BN_num_bits(key->rsa->n), filename, linenum);
97511b41d2SMark Murray 	}
98a8f6863aSKris Kennaway 	return 1;
99511b41d2SMark Murray }
100511b41d2SMark Murray 
101511b41d2SMark Murray /*
102511b41d2SMark Murray  * Checks whether the given host (which must be in all lowercase) is already
103511b41d2SMark Murray  * in the list of our known hosts. Returns HOST_OK if the host is known and
104511b41d2SMark Murray  * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
105511b41d2SMark Murray  * if the host is known but used to have a different host key.
106511b41d2SMark Murray  */
107511b41d2SMark Murray 
108511b41d2SMark Murray HostStatus
109ca3176e7SBrian Feldman check_host_in_hostfile(const char *filename, const char *host, Key *key,
110ca3176e7SBrian Feldman     Key *found, int *numret)
111511b41d2SMark Murray {
112511b41d2SMark Murray 	FILE *f;
113511b41d2SMark Murray 	char line[8192];
114511b41d2SMark Murray 	int linenum = 0;
115ca3176e7SBrian Feldman 	u_int kbits;
116511b41d2SMark Murray 	char *cp, *cp2;
117511b41d2SMark Murray 	HostStatus end_return;
118511b41d2SMark Murray 
119ca3176e7SBrian Feldman 	debug3("check_host_in_hostfile: filename %s", filename);
120a8f6863aSKris Kennaway 	if (key == NULL)
121a8f6863aSKris Kennaway 		fatal("no key to look up");
122511b41d2SMark Murray 	/* Open the file containing the list of known hosts. */
123511b41d2SMark Murray 	f = fopen(filename, "r");
124511b41d2SMark Murray 	if (!f)
125511b41d2SMark Murray 		return HOST_NEW;
126511b41d2SMark Murray 
127511b41d2SMark Murray 	/*
128511b41d2SMark Murray 	 * Return value when the loop terminates.  This is set to
129511b41d2SMark Murray 	 * HOST_CHANGED if we have seen a different key for the host and have
130511b41d2SMark Murray 	 * not found the proper one.
131511b41d2SMark Murray 	 */
132511b41d2SMark Murray 	end_return = HOST_NEW;
133511b41d2SMark Murray 
134ca3176e7SBrian Feldman 	/* Go through the file. */
135511b41d2SMark Murray 	while (fgets(line, sizeof(line), f)) {
136511b41d2SMark Murray 		cp = line;
137511b41d2SMark Murray 		linenum++;
138511b41d2SMark Murray 
139511b41d2SMark Murray 		/* Skip any leading whitespace, comments and empty lines. */
140511b41d2SMark Murray 		for (; *cp == ' ' || *cp == '\t'; cp++)
141511b41d2SMark Murray 			;
142511b41d2SMark Murray 		if (!*cp || *cp == '#' || *cp == '\n')
143511b41d2SMark Murray 			continue;
144511b41d2SMark Murray 
145511b41d2SMark Murray 		/* Find the end of the host name portion. */
146511b41d2SMark Murray 		for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
147511b41d2SMark Murray 			;
148511b41d2SMark Murray 
149511b41d2SMark Murray 		/* Check if the host name matches. */
150ca3176e7SBrian Feldman 		if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1)
151511b41d2SMark Murray 			continue;
152511b41d2SMark Murray 
153511b41d2SMark Murray 		/* Got a match.  Skip host name. */
154511b41d2SMark Murray 		cp = cp2;
155511b41d2SMark Murray 
156511b41d2SMark Murray 		/*
157511b41d2SMark Murray 		 * Extract the key from the line.  This will skip any leading
158511b41d2SMark Murray 		 * whitespace.  Ignore badly formatted lines.
159511b41d2SMark Murray 		 */
160a8f6863aSKris Kennaway 		if (!hostfile_read_key(&cp, &kbits, found))
161a8f6863aSKris Kennaway 			continue;
162a8f6863aSKris Kennaway 		if (!hostfile_check_key(kbits, found, host, filename, linenum))
163511b41d2SMark Murray 			continue;
164511b41d2SMark Murray 
165ca3176e7SBrian Feldman 		if (numret != NULL)
166ca3176e7SBrian Feldman 			*numret = linenum;
167ca3176e7SBrian Feldman 
168511b41d2SMark Murray 		/* Check if the current key is the same as the given key. */
169a8f6863aSKris Kennaway 		if (key_equal(key, found)) {
170511b41d2SMark Murray 			/* Ok, they match. */
171ca3176e7SBrian Feldman 			debug3("check_host_in_hostfile: match line %d", linenum);
172511b41d2SMark Murray 			fclose(f);
173511b41d2SMark Murray 			return HOST_OK;
174511b41d2SMark Murray 		}
175511b41d2SMark Murray 		/*
176511b41d2SMark Murray 		 * They do not match.  We will continue to go through the
177511b41d2SMark Murray 		 * file; however, we note that we will not return that it is
178511b41d2SMark Murray 		 * new.
179511b41d2SMark Murray 		 */
180511b41d2SMark Murray 		end_return = HOST_CHANGED;
181511b41d2SMark Murray 	}
182511b41d2SMark Murray 	/* Clear variables and close the file. */
183511b41d2SMark Murray 	fclose(f);
184511b41d2SMark Murray 
185511b41d2SMark Murray 	/*
186511b41d2SMark Murray 	 * Return either HOST_NEW or HOST_CHANGED, depending on whether we
187511b41d2SMark Murray 	 * saw a different key for the host.
188511b41d2SMark Murray 	 */
189511b41d2SMark Murray 	return end_return;
190511b41d2SMark Murray }
191511b41d2SMark Murray 
192511b41d2SMark Murray /*
193511b41d2SMark Murray  * Appends an entry to the host file.  Returns false if the entry could not
194511b41d2SMark Murray  * be appended.
195511b41d2SMark Murray  */
196511b41d2SMark Murray 
197511b41d2SMark Murray int
198a8f6863aSKris Kennaway add_host_to_hostfile(const char *filename, const char *host, Key *key)
199511b41d2SMark Murray {
200511b41d2SMark Murray 	FILE *f;
201a8f6863aSKris Kennaway 	int success = 0;
202a8f6863aSKris Kennaway 	if (key == NULL)
203e8aafc91SKris Kennaway 		return 1;	/* XXX ? */
204511b41d2SMark Murray 	f = fopen(filename, "a");
205511b41d2SMark Murray 	if (!f)
206511b41d2SMark Murray 		return 0;
207a8f6863aSKris Kennaway 	fprintf(f, "%s ", host);
208a8f6863aSKris Kennaway 	if (key_write(key, f)) {
209a8f6863aSKris Kennaway 		success = 1;
210a8f6863aSKris Kennaway 	} else {
211e8aafc91SKris Kennaway 		error("add_host_to_hostfile: saving key in %s failed", filename);
212511b41d2SMark Murray 	}
213e8aafc91SKris Kennaway 	fprintf(f, "\n");
214511b41d2SMark Murray 	fclose(f);
215a8f6863aSKris Kennaway 	return success;
216511b41d2SMark Murray }
217