Annotation of src/usr.bin/ssh/hostfile.c, Revision 1.18.2.4
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: *
1.18.2.3 jason 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"
1.18.2.4! jason 39: RCSID("$OpenBSD: hostfile.c,v 1.24 2001/01/21 19:05:49 markus Exp $");
1.1 deraadt 40:
41: #include "packet.h"
1.14 markus 42: #include "match.h"
43: #include "key.h"
44: #include "hostfile.h"
1.18.2.4! jason 45: #include "log.h"
1.1 deraadt 46:
1.9 markus 47: /*
1.14 markus 48: * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
49: * pointer over the key. Skips any whitespace at the beginning and at end.
1.9 markus 50: */
1.1 deraadt 51:
1.2 provos 52: int
1.18.2.4! jason 53: hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
1.1 deraadt 54: {
1.7 markus 55: char *cp;
56:
57: /* Skip leading whitespace. */
1.9 markus 58: for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
59: ;
1.1 deraadt 60:
1.18.2.4! jason 61: if (key_read(ret, &cp) != 1)
1.7 markus 62: return 0;
63:
64: /* Skip trailing whitespace. */
1.9 markus 65: for (; *cp == ' ' || *cp == '\t'; cp++)
66: ;
1.7 markus 67:
68: /* Return results. */
69: *cpp = cp;
1.18.2.4! jason 70: *bitsp = key_size(ret);
1.7 markus 71: return 1;
1.1 deraadt 72: }
73:
1.14 markus 74: int
1.18.2.4! jason 75: auth_rsa_read_key(char **cpp, u_int *bitsp, BIGNUM * e, BIGNUM * n)
1.14 markus 76: {
1.18.2.4! jason 77: Key *k = key_new(KEY_RSA1);
1.14 markus 78: int ret = hostfile_read_key(cpp, bitsp, k);
79: BN_copy(e, k->rsa->e);
80: BN_copy(n, k->rsa->n);
81: key_free(k);
82: return ret;
83: }
1.1 deraadt 84:
1.2 provos 85: int
1.14 markus 86: hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
1.1 deraadt 87: {
1.18.2.4! jason 88: if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
1.14 markus 89: return 1;
90: if (bits != BN_num_bits(key->rsa->n)) {
1.18 markus 91: log("Warning: %s, line %d: keysize mismatch for host %s: "
1.14 markus 92: "actual %d vs. announced %d.",
93: filename, linenum, host, BN_num_bits(key->rsa->n), bits);
1.18 markus 94: log("Warning: replace %d with %d in %s, line %d.",
1.14 markus 95: bits, BN_num_bits(key->rsa->n), filename, linenum);
1.1 deraadt 96: }
1.14 markus 97: return 1;
1.1 deraadt 98: }
99:
1.9 markus 100: /*
101: * Checks whether the given host (which must be in all lowercase) is already
102: * in the list of our known hosts. Returns HOST_OK if the host is known and
103: * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
104: * if the host is known but used to have a different host key.
105: */
1.1 deraadt 106:
1.2 provos 107: HostStatus
1.18.2.4! jason 108: check_host_in_hostfile(const char *filename, const char *host, Key *key,
! 109: Key *found, int *numret)
1.1 deraadt 110: {
1.7 markus 111: FILE *f;
112: char line[8192];
113: int linenum = 0;
1.18.2.4! jason 114: u_int kbits, hostlen;
1.7 markus 115: char *cp, *cp2;
116: HostStatus end_return;
117:
1.14 markus 118: if (key == NULL)
119: fatal("no key to look up");
1.7 markus 120: /* Open the file containing the list of known hosts. */
121: f = fopen(filename, "r");
122: if (!f)
123: return HOST_NEW;
124:
125: /* Cache the length of the host name. */
126: hostlen = strlen(host);
127:
1.9 markus 128: /*
129: * Return value when the loop terminates. This is set to
130: * HOST_CHANGED if we have seen a different key for the host and have
131: * not found the proper one.
132: */
1.7 markus 133: end_return = HOST_NEW;
134:
135: /* Go trough the file. */
136: while (fgets(line, sizeof(line), f)) {
137: cp = line;
138: linenum++;
139:
1.9 markus 140: /* Skip any leading whitespace, comments and empty lines. */
141: for (; *cp == ' ' || *cp == '\t'; cp++)
142: ;
1.7 markus 143: if (!*cp || *cp == '#' || *cp == '\n')
144: continue;
145:
146: /* Find the end of the host name portion. */
1.9 markus 147: for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
148: ;
1.7 markus 149:
150: /* Check if the host name matches. */
1.18.2.4! jason 151: if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1)
1.7 markus 152: continue;
153:
154: /* Got a match. Skip host name. */
155: cp = cp2;
156:
1.9 markus 157: /*
158: * Extract the key from the line. This will skip any leading
159: * whitespace. Ignore badly formatted lines.
160: */
1.14 markus 161: if (!hostfile_read_key(&cp, &kbits, found))
162: continue;
163: if (!hostfile_check_key(kbits, found, host, filename, linenum))
1.7 markus 164: continue;
1.18.2.4! jason 165:
! 166: if (numret != NULL)
! 167: *numret = linenum;
1.7 markus 168:
169: /* Check if the current key is the same as the given key. */
1.14 markus 170: if (key_equal(key, found)) {
1.7 markus 171: /* Ok, they match. */
172: fclose(f);
173: return HOST_OK;
174: }
1.9 markus 175: /*
176: * They do not match. We will continue to go through the
177: * file; however, we note that we will not return that it is
178: * new.
179: */
1.7 markus 180: end_return = HOST_CHANGED;
1.1 deraadt 181: }
1.7 markus 182: /* Clear variables and close the file. */
183: fclose(f);
184:
1.9 markus 185: /*
186: * Return either HOST_NEW or HOST_CHANGED, depending on whether we
187: * saw a different key for the host.
188: */
1.7 markus 189: return end_return;
1.1 deraadt 190: }
191:
1.9 markus 192: /*
193: * Appends an entry to the host file. Returns false if the entry could not
194: * be appended.
195: */
1.1 deraadt 196:
1.2 provos 197: int
1.14 markus 198: add_host_to_hostfile(const char *filename, const char *host, Key *key)
1.1 deraadt 199: {
1.7 markus 200: FILE *f;
1.14 markus 201: int success = 0;
202: if (key == NULL)
1.17 markus 203: return 1; /* XXX ? */
1.7 markus 204: f = fopen(filename, "a");
205: if (!f)
206: return 0;
1.14 markus 207: fprintf(f, "%s ", host);
208: if (key_write(key, f)) {
209: success = 1;
210: } else {
1.17 markus 211: error("add_host_to_hostfile: saving key in %s failed", filename);
1.7 markus 212: }
1.17 markus 213: fprintf(f, "\n");
1.7 markus 214: fclose(f);
1.14 markus 215: return success;
1.1 deraadt 216: }
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