Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 1 | /* |
| 2 | |
| 3 | authfile.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: Mon Mar 27 03:52:05 1995 ylo |
| 11 | |
| 12 | This file contains functions for reading and writing identity files, and |
| 13 | for reading the passphrase from the user. |
| 14 | |
| 15 | */ |
| 16 | |
Damien Miller | 7f6ea02 | 1999-10-28 13:25:17 +1000 | [diff] [blame] | 17 | #include "config.h" |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 18 | #include "includes.h" |
Damien Miller | 7f6ea02 | 1999-10-28 13:25:17 +1000 | [diff] [blame] | 19 | RCSID("$Id: authfile.c,v 1.2 1999/10/28 03:25:17 damien Exp $"); |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 20 | |
Damien Miller | 7f6ea02 | 1999-10-28 13:25:17 +1000 | [diff] [blame] | 21 | #ifdef HAVE_OPENSSL |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 22 | #include <openssl/bn.h> |
Damien Miller | 7f6ea02 | 1999-10-28 13:25:17 +1000 | [diff] [blame] | 23 | #endif |
| 24 | #ifdef HAVE_SSL |
| 25 | #include <ssl/bn.h> |
| 26 | #endif |
| 27 | |
Damien Miller | d4a8b7e | 1999-10-27 13:42:43 +1000 | [diff] [blame] | 28 | #include "xmalloc.h" |
| 29 | #include "buffer.h" |
| 30 | #include "bufaux.h" |
| 31 | #include "cipher.h" |
| 32 | #include "ssh.h" |
| 33 | |
| 34 | /* Version identification string for identity files. */ |
| 35 | #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n" |
| 36 | |
| 37 | /* Saves the authentication (private) key in a file, encrypting it with |
| 38 | passphrase. The identification of the file (lowest 64 bits of n) |
| 39 | will precede the key to provide identification of the key without |
| 40 | needing a passphrase. */ |
| 41 | |
| 42 | int |
| 43 | save_private_key(const char *filename, const char *passphrase, |
| 44 | RSA *key, const char *comment) |
| 45 | { |
| 46 | Buffer buffer, encrypted; |
| 47 | char buf[100], *cp; |
| 48 | int f, i; |
| 49 | CipherContext cipher; |
| 50 | int cipher_type; |
| 51 | u_int32_t rand; |
| 52 | |
| 53 | /* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting to |
| 54 | another cipher; otherwise use SSH_AUTHFILE_CIPHER. */ |
| 55 | if (strcmp(passphrase, "") == 0) |
| 56 | cipher_type = SSH_CIPHER_NONE; |
| 57 | else |
| 58 | cipher_type = SSH_AUTHFILE_CIPHER; |
| 59 | |
| 60 | /* This buffer is used to built the secret part of the private key. */ |
| 61 | buffer_init(&buffer); |
| 62 | |
| 63 | /* Put checkbytes for checking passphrase validity. */ |
| 64 | rand = arc4random(); |
| 65 | buf[0] = rand & 0xff; |
| 66 | buf[1] = (rand >> 8) & 0xff; |
| 67 | buf[2] = buf[0]; |
| 68 | buf[3] = buf[1]; |
| 69 | buffer_append(&buffer, buf, 4); |
| 70 | |
| 71 | /* Store the private key (n and e will not be stored because they will |
| 72 | be stored in plain text, and storing them also in encrypted format |
| 73 | would just give known plaintext). */ |
| 74 | buffer_put_bignum(&buffer, key->d); |
| 75 | buffer_put_bignum(&buffer, key->iqmp); |
| 76 | buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */ |
| 77 | buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */ |
| 78 | |
| 79 | /* Pad the part to be encrypted until its size is a multiple of 8. */ |
| 80 | while (buffer_len(&buffer) % 8 != 0) |
| 81 | buffer_put_char(&buffer, 0); |
| 82 | |
| 83 | /* This buffer will be used to contain the data in the file. */ |
| 84 | buffer_init(&encrypted); |
| 85 | |
| 86 | /* First store keyfile id string. */ |
| 87 | cp = AUTHFILE_ID_STRING; |
| 88 | for (i = 0; cp[i]; i++) |
| 89 | buffer_put_char(&encrypted, cp[i]); |
| 90 | buffer_put_char(&encrypted, 0); |
| 91 | |
| 92 | /* Store cipher type. */ |
| 93 | buffer_put_char(&encrypted, cipher_type); |
| 94 | buffer_put_int(&encrypted, 0); /* For future extension */ |
| 95 | |
| 96 | /* Store public key. This will be in plain text. */ |
| 97 | buffer_put_int(&encrypted, BN_num_bits(key->n)); |
| 98 | buffer_put_bignum(&encrypted, key->n); |
| 99 | buffer_put_bignum(&encrypted, key->e); |
| 100 | buffer_put_string(&encrypted, comment, strlen(comment)); |
| 101 | |
| 102 | /* Allocate space for the private part of the key in the buffer. */ |
| 103 | buffer_append_space(&encrypted, &cp, buffer_len(&buffer)); |
| 104 | |
| 105 | cipher_set_key_string(&cipher, cipher_type, passphrase, 1); |
| 106 | cipher_encrypt(&cipher, (unsigned char *)cp, |
| 107 | (unsigned char *)buffer_ptr(&buffer), |
| 108 | buffer_len(&buffer)); |
| 109 | memset(&cipher, 0, sizeof(cipher)); |
| 110 | |
| 111 | /* Destroy temporary data. */ |
| 112 | memset(buf, 0, sizeof(buf)); |
| 113 | buffer_free(&buffer); |
| 114 | |
| 115 | /* Write to a file. */ |
| 116 | f = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0600); |
| 117 | if (f < 0) |
| 118 | return 0; |
| 119 | |
| 120 | if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) != |
| 121 | buffer_len(&encrypted)) |
| 122 | { |
| 123 | debug("Write to key file %.200s failed: %.100s", filename, |
| 124 | strerror(errno)); |
| 125 | buffer_free(&encrypted); |
| 126 | close(f); |
| 127 | remove(filename); |
| 128 | return 0; |
| 129 | } |
| 130 | close(f); |
| 131 | buffer_free(&encrypted); |
| 132 | return 1; |
| 133 | } |
| 134 | |
| 135 | /* Loads the public part of the key file. Returns 0 if an error |
| 136 | was encountered (the file does not exist or is not readable), and |
| 137 | non-zero otherwise. */ |
| 138 | |
| 139 | int |
| 140 | load_public_key(const char *filename, RSA *pub, |
| 141 | char **comment_return) |
| 142 | { |
| 143 | int f, i; |
| 144 | off_t len; |
| 145 | Buffer buffer; |
| 146 | char *cp; |
| 147 | |
| 148 | /* Read data from the file into the buffer. */ |
| 149 | f = open(filename, O_RDONLY); |
| 150 | if (f < 0) |
| 151 | return 0; |
| 152 | |
| 153 | len = lseek(f, (off_t)0, SEEK_END); |
| 154 | lseek(f, (off_t)0, SEEK_SET); |
| 155 | |
| 156 | buffer_init(&buffer); |
| 157 | buffer_append_space(&buffer, &cp, len); |
| 158 | |
| 159 | if (read(f, cp, (size_t)len) != (size_t)len) |
| 160 | { |
| 161 | debug("Read from key file %.200s failed: %.100s", filename, |
| 162 | strerror(errno)); |
| 163 | buffer_free(&buffer); |
| 164 | close(f); |
| 165 | return 0; |
| 166 | } |
| 167 | close(f); |
| 168 | |
| 169 | /* Check that it is at least big enought to contain the ID string. */ |
| 170 | if (len < strlen(AUTHFILE_ID_STRING) + 1) |
| 171 | { |
| 172 | debug("Bad key file %.200s.", filename); |
| 173 | buffer_free(&buffer); |
| 174 | return 0; |
| 175 | } |
| 176 | |
| 177 | /* Make sure it begins with the id string. Consume the id string from |
| 178 | the buffer. */ |
| 179 | for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++) |
| 180 | if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i]) |
| 181 | { |
| 182 | debug("Bad key file %.200s.", filename); |
| 183 | buffer_free(&buffer); |
| 184 | return 0; |
| 185 | } |
| 186 | |
| 187 | /* Skip cipher type and reserved data. */ |
| 188 | (void)buffer_get_char(&buffer); /* cipher type */ |
| 189 | (void)buffer_get_int(&buffer); /* reserved */ |
| 190 | |
| 191 | /* Read the public key from the buffer. */ |
| 192 | buffer_get_int(&buffer); |
| 193 | pub->n = BN_new(); |
| 194 | buffer_get_bignum(&buffer, pub->n); |
| 195 | pub->e = BN_new(); |
| 196 | buffer_get_bignum(&buffer, pub->e); |
| 197 | if (comment_return) |
| 198 | *comment_return = buffer_get_string(&buffer, NULL); |
| 199 | /* The encrypted private part is not parsed by this function. */ |
| 200 | |
| 201 | buffer_free(&buffer); |
| 202 | |
| 203 | return 1; |
| 204 | } |
| 205 | |
| 206 | /* Loads the private key from the file. Returns 0 if an error is encountered |
| 207 | (file does not exist or is not readable, or passphrase is bad). |
| 208 | This initializes the private key. */ |
| 209 | |
| 210 | int |
| 211 | load_private_key(const char *filename, const char *passphrase, |
| 212 | RSA *prv, char **comment_return) |
| 213 | { |
| 214 | int f, i, check1, check2, cipher_type; |
| 215 | off_t len; |
| 216 | Buffer buffer, decrypted; |
| 217 | char *cp; |
| 218 | CipherContext cipher; |
| 219 | BN_CTX *ctx; |
| 220 | BIGNUM *aux; |
| 221 | struct stat st; |
| 222 | |
| 223 | /* Read the file into the buffer. */ |
| 224 | f = open(filename, O_RDONLY); |
| 225 | if (f < 0) |
| 226 | return 0; |
| 227 | |
| 228 | /* We assume we are called under uid of the owner of the file */ |
| 229 | if (fstat(f, &st) < 0 || |
| 230 | (st.st_uid != 0 && st.st_uid != getuid()) || |
| 231 | (st.st_mode & 077) != 0) { |
| 232 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 233 | error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); |
| 234 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| 235 | error("Bad ownership or mode(0%3.3o) for '%s'.", |
| 236 | st.st_mode & 0777, filename); |
| 237 | error("It is recommended that your private key files are NOT accessible by others."); |
| 238 | return 0; |
| 239 | } |
| 240 | |
| 241 | len = lseek(f, (off_t)0, SEEK_END); |
| 242 | lseek(f, (off_t)0, SEEK_SET); |
| 243 | |
| 244 | buffer_init(&buffer); |
| 245 | buffer_append_space(&buffer, &cp, len); |
| 246 | |
| 247 | if (read(f, cp, (size_t)len) != (size_t)len) |
| 248 | { |
| 249 | debug("Read from key file %.200s failed: %.100s", filename, |
| 250 | strerror(errno)); |
| 251 | buffer_free(&buffer); |
| 252 | close(f); |
| 253 | return 0; |
| 254 | } |
| 255 | close(f); |
| 256 | |
| 257 | /* Check that it is at least big enought to contain the ID string. */ |
| 258 | if (len < strlen(AUTHFILE_ID_STRING) + 1) |
| 259 | { |
| 260 | debug("Bad key file %.200s.", filename); |
| 261 | buffer_free(&buffer); |
| 262 | return 0; |
| 263 | } |
| 264 | |
| 265 | /* Make sure it begins with the id string. Consume the id string from |
| 266 | the buffer. */ |
| 267 | for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++) |
| 268 | if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i]) |
| 269 | { |
| 270 | debug("Bad key file %.200s.", filename); |
| 271 | buffer_free(&buffer); |
| 272 | return 0; |
| 273 | } |
| 274 | |
| 275 | /* Read cipher type. */ |
| 276 | cipher_type = buffer_get_char(&buffer); |
| 277 | (void)buffer_get_int(&buffer); /* Reserved data. */ |
| 278 | |
| 279 | /* Read the public key from the buffer. */ |
| 280 | buffer_get_int(&buffer); |
| 281 | prv->n = BN_new(); |
| 282 | buffer_get_bignum(&buffer, prv->n); |
| 283 | prv->e = BN_new(); |
| 284 | buffer_get_bignum(&buffer, prv->e); |
| 285 | if (comment_return) |
| 286 | *comment_return = buffer_get_string(&buffer, NULL); |
| 287 | else |
| 288 | xfree(buffer_get_string(&buffer, NULL)); |
| 289 | |
| 290 | /* Check that it is a supported cipher. */ |
| 291 | if (((cipher_mask() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) & |
| 292 | (1 << cipher_type)) == 0) |
| 293 | { |
| 294 | debug("Unsupported cipher %.100s used in key file %.200s.", |
| 295 | cipher_name(cipher_type), filename); |
| 296 | buffer_free(&buffer); |
| 297 | goto fail; |
| 298 | } |
| 299 | |
| 300 | /* Initialize space for decrypted data. */ |
| 301 | buffer_init(&decrypted); |
| 302 | buffer_append_space(&decrypted, &cp, buffer_len(&buffer)); |
| 303 | |
| 304 | /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */ |
| 305 | cipher_set_key_string(&cipher, cipher_type, passphrase, 0); |
| 306 | cipher_decrypt(&cipher, (unsigned char *)cp, |
| 307 | (unsigned char *)buffer_ptr(&buffer), |
| 308 | buffer_len(&buffer)); |
| 309 | |
| 310 | buffer_free(&buffer); |
| 311 | |
| 312 | check1 = buffer_get_char(&decrypted); |
| 313 | check2 = buffer_get_char(&decrypted); |
| 314 | if (check1 != buffer_get_char(&decrypted) || |
| 315 | check2 != buffer_get_char(&decrypted)) |
| 316 | { |
| 317 | if (strcmp(passphrase, "") != 0) |
| 318 | debug("Bad passphrase supplied for key file %.200s.", filename); |
| 319 | /* Bad passphrase. */ |
| 320 | buffer_free(&decrypted); |
| 321 | fail: |
| 322 | BN_clear_free(prv->n); |
| 323 | BN_clear_free(prv->e); |
| 324 | if (comment_return) |
| 325 | xfree(*comment_return); |
| 326 | return 0; |
| 327 | } |
| 328 | |
| 329 | /* Read the rest of the private key. */ |
| 330 | prv->d = BN_new(); |
| 331 | buffer_get_bignum(&decrypted, prv->d); |
| 332 | prv->iqmp = BN_new(); |
| 333 | buffer_get_bignum(&decrypted, prv->iqmp); /* u */ |
| 334 | /* in SSL and SSH p and q are exchanged */ |
| 335 | prv->q = BN_new(); |
| 336 | buffer_get_bignum(&decrypted, prv->q); /* p */ |
| 337 | prv->p = BN_new(); |
| 338 | buffer_get_bignum(&decrypted, prv->p); /* q */ |
| 339 | |
| 340 | ctx = BN_CTX_new(); |
| 341 | aux = BN_new(); |
| 342 | |
| 343 | BN_sub(aux, prv->q, BN_value_one()); |
| 344 | prv->dmq1 = BN_new(); |
| 345 | BN_mod(prv->dmq1, prv->d, aux, ctx); |
| 346 | |
| 347 | BN_sub(aux, prv->p, BN_value_one()); |
| 348 | prv->dmp1 = BN_new(); |
| 349 | BN_mod(prv->dmp1, prv->d, aux, ctx); |
| 350 | |
| 351 | BN_clear_free(aux); |
| 352 | BN_CTX_free(ctx); |
| 353 | |
| 354 | buffer_free(&decrypted); |
| 355 | |
| 356 | return 1; |
| 357 | } |