Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 2 | * |
| 3 | * hostfile.c |
| 4 | * |
| 5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| 6 | * |
| 7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| 8 | * All rights reserved |
| 9 | * |
| 10 | * Created: Thu Jun 29 07:10:56 1995 ylo |
| 11 | * |
| 12 | * Functions for manipulating the known hosts files. |
| 13 | * |
| 14 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 15 | |
| 16 | #include "includes.h" |
Damien Miller | aae6c61 | 1999-12-06 11:47:28 +1100 | [diff] [blame] | 17 | RCSID("$OpenBSD: hostfile.c,v 1.10 1999/12/02 20:18:59 markus Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 18 | |
| 19 | #include "packet.h" |
| 20 | #include "ssh.h" |
| 21 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 22 | /* |
| 23 | * Reads a multiple-precision integer in hex from the buffer, and advances |
| 24 | * the pointer. The integer must already be initialized. This function is |
| 25 | * permitted to modify the buffer. This leaves *cpp to point just beyond the |
| 26 | * last processed (and maybe modified) character. Note that this may modify |
| 27 | * the buffer containing the number. |
| 28 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 29 | |
| 30 | int |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 31 | auth_rsa_read_bignum(char **cpp, BIGNUM * value) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 32 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 33 | char *cp = *cpp; |
| 34 | int len, old; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 35 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 36 | /* Skip any leading whitespace. */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 37 | for (; *cp == ' ' || *cp == '\t'; cp++) |
| 38 | ; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 39 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 40 | /* Check that it begins with a hex digit. */ |
| 41 | if (*cp < '0' || *cp > '9') |
| 42 | return 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 43 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 44 | /* Save starting position. */ |
| 45 | *cpp = cp; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 46 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 47 | /* Move forward until all hex digits skipped. */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 48 | for (; *cp >= '0' && *cp <= '9'; cp++) |
| 49 | ; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 50 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 51 | /* Compute the length of the hex number. */ |
| 52 | len = cp - *cpp; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 53 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 54 | /* Save the old terminating character, and replace it by \0. */ |
| 55 | old = *cp; |
| 56 | *cp = 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 57 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 58 | /* Parse the number. */ |
| 59 | if (BN_dec2bn(&value, *cpp) == 0) |
| 60 | return 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 61 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 62 | /* Restore old terminating character. */ |
| 63 | *cp = old; |
| 64 | |
| 65 | /* Move beyond the number and return success. */ |
| 66 | *cpp = cp; |
| 67 | return 1; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 68 | } |
| 69 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 70 | /* |
| 71 | * Parses an RSA key (number of bits, e, n) from a string. Moves the pointer |
| 72 | * over the key. Skips any whitespace at the beginning and at end. |
| 73 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 74 | |
| 75 | int |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 76 | auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM * e, BIGNUM * n) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 77 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 78 | unsigned int bits; |
| 79 | char *cp; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 80 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 81 | /* Skip leading whitespace. */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 82 | for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++) |
| 83 | ; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 84 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 85 | /* Get number of bits. */ |
| 86 | if (*cp < '0' || *cp > '9') |
| 87 | return 0; /* Bad bit count... */ |
| 88 | for (bits = 0; *cp >= '0' && *cp <= '9'; cp++) |
| 89 | bits = 10 * bits + *cp - '0'; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 90 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 91 | /* Get public exponent. */ |
| 92 | if (!auth_rsa_read_bignum(&cp, e)) |
| 93 | return 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 94 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 95 | /* Get public modulus. */ |
| 96 | if (!auth_rsa_read_bignum(&cp, n)) |
| 97 | return 0; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 98 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 99 | /* Skip trailing whitespace. */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 100 | for (; *cp == ' ' || *cp == '\t'; cp++) |
| 101 | ; |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 102 | |
| 103 | /* Return results. */ |
| 104 | *cpp = cp; |
| 105 | *bitsp = bits; |
| 106 | return 1; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 107 | } |
| 108 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 109 | /* |
| 110 | * Tries to match the host name (which must be in all lowercase) against the |
| 111 | * comma-separated sequence of subpatterns (each possibly preceded by ! to |
| 112 | * indicate negation). Returns true if there is a positive match; zero |
| 113 | * otherwise. |
| 114 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 115 | |
| 116 | int |
| 117 | match_hostname(const char *host, const char *pattern, unsigned int len) |
| 118 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 119 | char sub[1024]; |
| 120 | int negated; |
| 121 | int got_positive; |
| 122 | unsigned int i, subi; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 123 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 124 | got_positive = 0; |
| 125 | for (i = 0; i < len;) { |
| 126 | /* Check if the subpattern is negated. */ |
| 127 | if (pattern[i] == '!') { |
| 128 | negated = 1; |
| 129 | i++; |
| 130 | } else |
| 131 | negated = 0; |
| 132 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 133 | /* |
| 134 | * Extract the subpattern up to a comma or end. Convert the |
| 135 | * subpattern to lowercase. |
| 136 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 137 | for (subi = 0; |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 138 | i < len && subi < sizeof(sub) - 1 && pattern[i] != ','; |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 139 | subi++, i++) |
| 140 | sub[subi] = isupper(pattern[i]) ? tolower(pattern[i]) : pattern[i]; |
| 141 | /* If subpattern too long, return failure (no match). */ |
| 142 | if (subi >= sizeof(sub) - 1) |
| 143 | return 0; |
| 144 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 145 | /* If the subpattern was terminated by a comma, skip the comma. */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 146 | if (i < len && pattern[i] == ',') |
| 147 | i++; |
| 148 | |
| 149 | /* Null-terminate the subpattern. */ |
| 150 | sub[subi] = '\0'; |
| 151 | |
| 152 | /* Try to match the subpattern against the host name. */ |
| 153 | if (match_pattern(host, sub)) { |
| 154 | if (negated) |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 155 | return 0; /* Fail */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 156 | else |
| 157 | got_positive = 1; |
| 158 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 159 | } |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 160 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 161 | /* |
| 162 | * Return success if got a positive match. If there was a negative |
| 163 | * match, we have already returned zero and never get here. |
| 164 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 165 | return got_positive; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 166 | } |
| 167 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 168 | /* |
| 169 | * Checks whether the given host (which must be in all lowercase) is already |
| 170 | * in the list of our known hosts. Returns HOST_OK if the host is known and |
| 171 | * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED |
| 172 | * if the host is known but used to have a different host key. |
| 173 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 174 | |
| 175 | HostStatus |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 176 | check_host_in_hostfile(const char *filename, const char *host, |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 177 | BIGNUM * e, BIGNUM * n, BIGNUM * ke, BIGNUM * kn) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 178 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 179 | FILE *f; |
| 180 | char line[8192]; |
| 181 | int linenum = 0; |
| 182 | unsigned int bits, kbits, hostlen; |
| 183 | char *cp, *cp2; |
| 184 | HostStatus end_return; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 185 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 186 | /* Open the file containing the list of known hosts. */ |
| 187 | f = fopen(filename, "r"); |
| 188 | if (!f) |
| 189 | return HOST_NEW; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 190 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 191 | /* Cache the length of the host name. */ |
| 192 | hostlen = strlen(host); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 193 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 194 | /* |
| 195 | * Return value when the loop terminates. This is set to |
| 196 | * HOST_CHANGED if we have seen a different key for the host and have |
| 197 | * not found the proper one. |
| 198 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 199 | end_return = HOST_NEW; |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 200 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 201 | /* size of modulus 'n' */ |
| 202 | bits = BN_num_bits(n); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 203 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 204 | /* Go trough the file. */ |
| 205 | while (fgets(line, sizeof(line), f)) { |
| 206 | cp = line; |
| 207 | linenum++; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 208 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 209 | /* Skip any leading whitespace, comments and empty lines. */ |
| 210 | for (; *cp == ' ' || *cp == '\t'; cp++) |
| 211 | ; |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 212 | if (!*cp || *cp == '#' || *cp == '\n') |
| 213 | continue; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 214 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 215 | /* Find the end of the host name portion. */ |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 216 | for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++) |
| 217 | ; |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 218 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 219 | /* Check if the host name matches. */ |
| 220 | if (!match_hostname(host, cp, (unsigned int) (cp2 - cp))) |
| 221 | continue; |
| 222 | |
| 223 | /* Got a match. Skip host name. */ |
| 224 | cp = cp2; |
| 225 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 226 | /* |
| 227 | * Extract the key from the line. This will skip any leading |
| 228 | * whitespace. Ignore badly formatted lines. |
| 229 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 230 | if (!auth_rsa_read_key(&cp, &kbits, ke, kn)) |
| 231 | continue; |
| 232 | |
| 233 | if (kbits != BN_num_bits(kn)) { |
Damien Miller | aae6c61 | 1999-12-06 11:47:28 +1100 | [diff] [blame] | 234 | error("Warning: %s, line %d: keysize mismatch for host %s: " |
| 235 | "actual %d vs. announced %d.", |
| 236 | filename, linenum, host, BN_num_bits(kn), kbits); |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 237 | error("Warning: replace %d with %d in %s, line %d.", |
| 238 | kbits, BN_num_bits(kn), filename, linenum); |
| 239 | } |
| 240 | /* Check if the current key is the same as the given key. */ |
| 241 | if (BN_cmp(ke, e) == 0 && BN_cmp(kn, n) == 0) { |
| 242 | /* Ok, they match. */ |
| 243 | fclose(f); |
| 244 | return HOST_OK; |
| 245 | } |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 246 | /* |
| 247 | * They do not match. We will continue to go through the |
| 248 | * file; however, we note that we will not return that it is |
| 249 | * new. |
| 250 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 251 | end_return = HOST_CHANGED; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 252 | } |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 253 | /* Clear variables and close the file. */ |
| 254 | fclose(f); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 255 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 256 | /* |
| 257 | * Return either HOST_NEW or HOST_CHANGED, depending on whether we |
| 258 | * saw a different key for the host. |
| 259 | */ |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 260 | return end_return; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 261 | } |
| 262 | |
Damien Miller | 5428f64 | 1999-11-25 11:54:57 +1100 | [diff] [blame] | 263 | /* |
| 264 | * Appends an entry to the host file. Returns false if the entry could not |
| 265 | * be appended. |
| 266 | */ |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 267 | |
| 268 | int |
| 269 | add_host_to_hostfile(const char *filename, const char *host, |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 270 | BIGNUM * e, BIGNUM * n) |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 271 | { |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 272 | FILE *f; |
| 273 | char *buf; |
| 274 | unsigned int bits; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 275 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 276 | /* Open the file for appending. */ |
| 277 | f = fopen(filename, "a"); |
| 278 | if (!f) |
| 279 | return 0; |
Damien Miller | 7e8e820 | 1999-11-16 13:37:16 +1100 | [diff] [blame] | 280 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 281 | /* size of modulus 'n' */ |
| 282 | bits = BN_num_bits(n); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 283 | |
Damien Miller | 95def09 | 1999-11-25 00:26:21 +1100 | [diff] [blame] | 284 | /* Print the host name and key to the file. */ |
| 285 | fprintf(f, "%s %u ", host, bits); |
| 286 | buf = BN_bn2dec(e); |
| 287 | if (buf == NULL) { |
| 288 | error("add_host_to_hostfile: BN_bn2dec(e) failed"); |
| 289 | fclose(f); |
| 290 | return 0; |
| 291 | } |
| 292 | fprintf(f, "%s ", buf); |
| 293 | free(buf); |
| 294 | buf = BN_bn2dec(n); |
| 295 | if (buf == NULL) { |
| 296 | error("add_host_to_hostfile: BN_bn2dec(n) failed"); |
| 297 | fclose(f); |
| 298 | return 0; |
| 299 | } |
| 300 | fprintf(f, "%s\n", buf); |
| 301 | free(buf); |
| 302 | |
| 303 | /* Close the file. */ |
| 304 | fclose(f); |
| 305 | return 1; |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 306 | } |