Annotation of src/usr.bin/ssh/hostfile.c, Revision 1.21
1.1 deraadt 1: /*
1.8 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Functions for manipulating the known hosts files.
1.16 markus 6: *
1.20 deraadt 7: * As far as I am concerned, the code I have written for this software
8: * can be used freely for any purpose. Any derived versions of this
9: * software must be clearly marked as such, and if the derived work is
10: * incompatible with the protocol description in the RFC file, it must be
11: * called by a name other than "ssh" or "Secure Shell".
12: *
13: *
14: * Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
15: * Copyright (c) 1999 Niels Provos. All rights reserved.
16: *
17: * Redistribution and use in source and binary forms, with or without
18: * modification, are permitted provided that the following conditions
19: * are met:
20: * 1. Redistributions of source code must retain the above copyright
21: * notice, this list of conditions and the following disclaimer.
22: * 2. Redistributions in binary form must reproduce the above copyright
23: * notice, this list of conditions and the following disclaimer in the
24: * documentation and/or other materials provided with the distribution.
25: *
26: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.8 deraadt 36: */
1.1 deraadt 37:
38: #include "includes.h"
1.21 ! markus 39: RCSID("$OpenBSD: hostfile.c,v 1.20 2000/09/07 20:27:51 deraadt Exp $");
1.1 deraadt 40:
41: #include "packet.h"
1.14 markus 42: #include "match.h"
1.1 deraadt 43: #include "ssh.h"
1.15 markus 44: #include <openssl/rsa.h>
45: #include <openssl/dsa.h>
1.14 markus 46: #include "key.h"
47: #include "hostfile.h"
1.1 deraadt 48:
1.9 markus 49: /*
1.14 markus 50: * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
51: * pointer over the key. Skips any whitespace at the beginning and at end.
1.9 markus 52: */
1.1 deraadt 53:
1.2 provos 54: int
1.14 markus 55: hostfile_read_key(char **cpp, unsigned int *bitsp, Key *ret)
1.1 deraadt 56: {
1.7 markus 57: char *cp;
58:
59: /* Skip leading whitespace. */
1.9 markus 60: for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
61: ;
1.1 deraadt 62:
1.21 ! markus 63: if (key_read(ret, &cp) != 1)
1.7 markus 64: return 0;
65:
66: /* Skip trailing whitespace. */
1.9 markus 67: for (; *cp == ' ' || *cp == '\t'; cp++)
68: ;
1.7 markus 69:
70: /* Return results. */
71: *cpp = cp;
1.21 ! markus 72: *bitsp = key_size(ret);
1.7 markus 73: return 1;
1.1 deraadt 74: }
75:
1.14 markus 76: int
77: auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n)
78: {
1.21 ! markus 79: Key *k = key_new(KEY_RSA1);
1.14 markus 80: int ret = hostfile_read_key(cpp, bitsp, k);
81: BN_copy(e, k->rsa->e);
82: BN_copy(n, k->rsa->n);
83: key_free(k);
84: return ret;
85: }
1.1 deraadt 86:
1.2 provos 87: int
1.14 markus 88: hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
1.1 deraadt 89: {
1.21 ! markus 90: if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
1.14 markus 91: return 1;
92: if (bits != BN_num_bits(key->rsa->n)) {
1.18 markus 93: log("Warning: %s, line %d: keysize mismatch for host %s: "
1.14 markus 94: "actual %d vs. announced %d.",
95: filename, linenum, host, BN_num_bits(key->rsa->n), bits);
1.18 markus 96: log("Warning: replace %d with %d in %s, line %d.",
1.14 markus 97: bits, BN_num_bits(key->rsa->n), filename, linenum);
1.1 deraadt 98: }
1.14 markus 99: return 1;
1.1 deraadt 100: }
101:
1.9 markus 102: /*
103: * Checks whether the given host (which must be in all lowercase) is already
104: * in the list of our known hosts. Returns HOST_OK if the host is known and
105: * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
106: * if the host is known but used to have a different host key.
107: */
1.1 deraadt 108:
1.2 provos 109: HostStatus
1.14 markus 110: check_host_in_hostfile(const char *filename, const char *host, Key *key, Key *found)
1.1 deraadt 111: {
1.7 markus 112: FILE *f;
113: char line[8192];
114: int linenum = 0;
1.12 markus 115: unsigned int kbits, hostlen;
1.7 markus 116: char *cp, *cp2;
117: HostStatus end_return;
118:
1.14 markus 119: if (key == NULL)
120: fatal("no key to look up");
1.7 markus 121: /* Open the file containing the list of known hosts. */
122: f = fopen(filename, "r");
123: if (!f)
124: return HOST_NEW;
125:
126: /* Cache the length of the host name. */
127: hostlen = strlen(host);
128:
1.9 markus 129: /*
130: * Return value when the loop terminates. This is set to
131: * HOST_CHANGED if we have seen a different key for the host and have
132: * not found the proper one.
133: */
1.7 markus 134: end_return = HOST_NEW;
135:
136: /* Go trough the file. */
137: while (fgets(line, sizeof(line), f)) {
138: cp = line;
139: linenum++;
140:
1.9 markus 141: /* Skip any leading whitespace, comments and empty lines. */
142: for (; *cp == ' ' || *cp == '\t'; cp++)
143: ;
1.7 markus 144: if (!*cp || *cp == '#' || *cp == '\n')
145: continue;
146:
147: /* Find the end of the host name portion. */
1.9 markus 148: for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
149: ;
1.7 markus 150:
151: /* Check if the host name matches. */
1.19 markus 152: if (match_hostname(host, cp, (unsigned int) (cp2 - cp)) != 1)
1.7 markus 153: continue;
154:
155: /* Got a match. Skip host name. */
156: cp = cp2;
157:
1.9 markus 158: /*
159: * Extract the key from the line. This will skip any leading
160: * whitespace. Ignore badly formatted lines.
161: */
1.14 markus 162: if (!hostfile_read_key(&cp, &kbits, found))
163: continue;
164: if (!hostfile_check_key(kbits, found, host, filename, linenum))
1.7 markus 165: continue;
166:
167: /* Check if the current key is the same as the given key. */
1.14 markus 168: if (key_equal(key, found)) {
1.7 markus 169: /* Ok, they match. */
170: fclose(f);
171: return HOST_OK;
172: }
1.9 markus 173: /*
174: * They do not match. We will continue to go through the
175: * file; however, we note that we will not return that it is
176: * new.
177: */
1.7 markus 178: end_return = HOST_CHANGED;
1.1 deraadt 179: }
1.7 markus 180: /* Clear variables and close the file. */
181: fclose(f);
182:
1.9 markus 183: /*
184: * Return either HOST_NEW or HOST_CHANGED, depending on whether we
185: * saw a different key for the host.
186: */
1.7 markus 187: return end_return;
1.1 deraadt 188: }
189:
1.9 markus 190: /*
191: * Appends an entry to the host file. Returns false if the entry could not
192: * be appended.
193: */
1.1 deraadt 194:
1.2 provos 195: int
1.14 markus 196: add_host_to_hostfile(const char *filename, const char *host, Key *key)
1.1 deraadt 197: {
1.7 markus 198: FILE *f;
1.14 markus 199: int success = 0;
200: if (key == NULL)
1.17 markus 201: return 1; /* XXX ? */
1.7 markus 202: f = fopen(filename, "a");
203: if (!f)
204: return 0;
1.14 markus 205: fprintf(f, "%s ", host);
206: if (key_write(key, f)) {
207: success = 1;
208: } else {
1.17 markus 209: error("add_host_to_hostfile: saving key in %s failed", filename);
1.7 markus 210: }
1.17 markus 211: fprintf(f, "\n");
1.7 markus 212: fclose(f);
1.14 markus 213: return success;
1.1 deraadt 214: }
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