1 /* 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 * This file contains functions for reading and writing identity files, and 6 * for reading the passphrase from the user. 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 * 14 * 15 * Copyright (c) 2000 Markus Friedl. 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. 36 */ 37 38 #include "includes.h" 39 RCSID("$OpenBSD: authfile.c,v 1.50 2002/06/24 14:55:38 markus Exp $"); 40 RCSID("$FreeBSD: src/crypto/openssh/authfile.c,v 1.2.2.5 2002/07/03 22:11:41 des Exp $"); 41 42 #include <openssl/err.h> 43 #include <openssl/evp.h> 44 #include <openssl/pem.h> 45 46 #include "cipher.h" 47 #include "xmalloc.h" 48 #include "buffer.h" 49 #include "bufaux.h" 50 #include "key.h" 51 #include "ssh.h" 52 #include "log.h" 53 #include "authfile.h" 54 #include "rsa.h" 55 56 /* Version identification string for SSH v1 identity files. */ 57 static const char authfile_id_string[] = 58 "SSH PRIVATE KEY FILE FORMAT 1.1\n"; 59 60 /* 61 * Saves the authentication (private) key in a file, encrypting it with 62 * passphrase. The identification of the file (lowest 64 bits of n) will 63 * precede the key to provide identification of the key without needing a 64 * passphrase. 65 */ 66 67 static int 68 key_save_private_rsa1(Key *key, const char *filename, const char *passphrase, 69 const char *comment) 70 { 71 Buffer buffer, encrypted; 72 u_char buf[100], *cp; 73 int fd, i, cipher_num; 74 CipherContext ciphercontext; 75 Cipher *cipher; 76 u_int32_t rand; 77 78 /* 79 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting 80 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER. 81 */ 82 cipher_num = (strcmp(passphrase, "") == 0) ? 83 SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER; 84 if ((cipher = cipher_by_number(cipher_num)) == NULL) 85 fatal("save_private_key_rsa: bad cipher"); 86 87 /* This buffer is used to built the secret part of the private key. */ 88 buffer_init(&buffer); 89 90 /* Put checkbytes for checking passphrase validity. */ 91 rand = arc4random(); 92 buf[0] = rand & 0xff; 93 buf[1] = (rand >> 8) & 0xff; 94 buf[2] = buf[0]; 95 buf[3] = buf[1]; 96 buffer_append(&buffer, buf, 4); 97 98 /* 99 * Store the private key (n and e will not be stored because they 100 * will be stored in plain text, and storing them also in encrypted 101 * format would just give known plaintext). 102 */ 103 buffer_put_bignum(&buffer, key->rsa->d); 104 buffer_put_bignum(&buffer, key->rsa->iqmp); 105 buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */ 106 buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */ 107 108 /* Pad the part to be encrypted until its size is a multiple of 8. */ 109 while (buffer_len(&buffer) % 8 != 0) 110 buffer_put_char(&buffer, 0); 111 112 /* This buffer will be used to contain the data in the file. */ 113 buffer_init(&encrypted); 114 115 /* First store keyfile id string. */ 116 for (i = 0; authfile_id_string[i]; i++) 117 buffer_put_char(&encrypted, authfile_id_string[i]); 118 buffer_put_char(&encrypted, 0); 119 120 /* Store cipher type. */ 121 buffer_put_char(&encrypted, cipher_num); 122 buffer_put_int(&encrypted, 0); /* For future extension */ 123 124 /* Store public key. This will be in plain text. */ 125 buffer_put_int(&encrypted, BN_num_bits(key->rsa->n)); 126 buffer_put_bignum(&encrypted, key->rsa->n); 127 buffer_put_bignum(&encrypted, key->rsa->e); 128 buffer_put_cstring(&encrypted, comment); 129 130 /* Allocate space for the private part of the key in the buffer. */ 131 cp = buffer_append_space(&encrypted, buffer_len(&buffer)); 132 133 cipher_set_key_string(&ciphercontext, cipher, passphrase, 134 CIPHER_ENCRYPT); 135 cipher_crypt(&ciphercontext, cp, 136 buffer_ptr(&buffer), buffer_len(&buffer)); 137 cipher_cleanup(&ciphercontext); 138 memset(&ciphercontext, 0, sizeof(ciphercontext)); 139 140 /* Destroy temporary data. */ 141 memset(buf, 0, sizeof(buf)); 142 buffer_free(&buffer); 143 144 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600); 145 if (fd < 0) { 146 error("open %s failed: %s.", filename, strerror(errno)); 147 return 0; 148 } 149 if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) != 150 buffer_len(&encrypted)) { 151 error("write to key file %s failed: %s", filename, 152 strerror(errno)); 153 buffer_free(&encrypted); 154 close(fd); 155 unlink(filename); 156 return 0; 157 } 158 close(fd); 159 buffer_free(&encrypted); 160 return 1; 161 } 162 163 /* save SSH v2 key in OpenSSL PEM format */ 164 static int 165 key_save_private_pem(Key *key, const char *filename, const char *_passphrase, 166 const char *comment) 167 { 168 FILE *fp; 169 int fd; 170 int success = 0; 171 int len = strlen(_passphrase); 172 u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL; 173 const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL; 174 175 if (len > 0 && len <= 4) { 176 error("passphrase too short: have %d bytes, need > 4", len); 177 return 0; 178 } 179 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600); 180 if (fd < 0) { 181 error("open %s failed: %s.", filename, strerror(errno)); 182 return 0; 183 } 184 fp = fdopen(fd, "w"); 185 if (fp == NULL ) { 186 error("fdopen %s failed: %s.", filename, strerror(errno)); 187 close(fd); 188 return 0; 189 } 190 switch (key->type) { 191 case KEY_DSA: 192 success = PEM_write_DSAPrivateKey(fp, key->dsa, 193 cipher, passphrase, len, NULL, NULL); 194 break; 195 case KEY_RSA: 196 success = PEM_write_RSAPrivateKey(fp, key->rsa, 197 cipher, passphrase, len, NULL, NULL); 198 break; 199 } 200 fclose(fp); 201 return success; 202 } 203 204 int 205 key_save_private(Key *key, const char *filename, const char *passphrase, 206 const char *comment) 207 { 208 switch (key->type) { 209 case KEY_RSA1: 210 return key_save_private_rsa1(key, filename, passphrase, 211 comment); 212 break; 213 case KEY_DSA: 214 case KEY_RSA: 215 return key_save_private_pem(key, filename, passphrase, 216 comment); 217 break; 218 default: 219 break; 220 } 221 error("key_save_private: cannot save key type %d", key->type); 222 return 0; 223 } 224 225 /* 226 * Loads the public part of the ssh v1 key file. Returns NULL if an error was 227 * encountered (the file does not exist or is not readable), and the key 228 * otherwise. 229 */ 230 231 static Key * 232 key_load_public_rsa1(int fd, const char *filename, char **commentp) 233 { 234 Buffer buffer; 235 Key *pub; 236 char *cp; 237 int i; 238 off_t len; 239 240 len = lseek(fd, (off_t) 0, SEEK_END); 241 lseek(fd, (off_t) 0, SEEK_SET); 242 243 buffer_init(&buffer); 244 cp = buffer_append_space(&buffer, len); 245 246 if (read(fd, cp, (size_t) len) != (size_t) len) { 247 debug("Read from key file %.200s failed: %.100s", filename, 248 strerror(errno)); 249 buffer_free(&buffer); 250 return NULL; 251 } 252 253 /* Check that it is at least big enough to contain the ID string. */ 254 if (len < sizeof(authfile_id_string)) { 255 debug3("Not a RSA1 key file %.200s.", filename); 256 buffer_free(&buffer); 257 return NULL; 258 } 259 /* 260 * Make sure it begins with the id string. Consume the id string 261 * from the buffer. 262 */ 263 for (i = 0; i < sizeof(authfile_id_string); i++) 264 if (buffer_get_char(&buffer) != authfile_id_string[i]) { 265 debug3("Not a RSA1 key file %.200s.", filename); 266 buffer_free(&buffer); 267 return NULL; 268 } 269 /* Skip cipher type and reserved data. */ 270 (void) buffer_get_char(&buffer); /* cipher type */ 271 (void) buffer_get_int(&buffer); /* reserved */ 272 273 /* Read the public key from the buffer. */ 274 (void) buffer_get_int(&buffer); 275 pub = key_new(KEY_RSA1); 276 buffer_get_bignum(&buffer, pub->rsa->n); 277 buffer_get_bignum(&buffer, pub->rsa->e); 278 if (commentp) 279 *commentp = buffer_get_string(&buffer, NULL); 280 /* The encrypted private part is not parsed by this function. */ 281 282 buffer_free(&buffer); 283 return pub; 284 } 285 286 /* load public key from private-key file, works only for SSH v1 */ 287 Key * 288 key_load_public_type(int type, const char *filename, char **commentp) 289 { 290 Key *pub; 291 int fd; 292 293 if (type == KEY_RSA1) { 294 fd = open(filename, O_RDONLY); 295 if (fd < 0) 296 return NULL; 297 pub = key_load_public_rsa1(fd, filename, commentp); 298 close(fd); 299 return pub; 300 } 301 return NULL; 302 } 303 304 /* 305 * Loads the private key from the file. Returns 0 if an error is encountered 306 * (file does not exist or is not readable, or passphrase is bad). This 307 * initializes the private key. 308 * Assumes we are called under uid of the owner of the file. 309 */ 310 311 static Key * 312 key_load_private_rsa1(int fd, const char *filename, const char *passphrase, 313 char **commentp) 314 { 315 int i, check1, check2, cipher_type; 316 off_t len; 317 Buffer buffer, decrypted; 318 u_char *cp; 319 CipherContext ciphercontext; 320 Cipher *cipher; 321 Key *prv = NULL; 322 323 len = lseek(fd, (off_t) 0, SEEK_END); 324 lseek(fd, (off_t) 0, SEEK_SET); 325 326 buffer_init(&buffer); 327 cp = buffer_append_space(&buffer, len); 328 329 if (read(fd, cp, (size_t) len) != (size_t) len) { 330 debug("Read from key file %.200s failed: %.100s", filename, 331 strerror(errno)); 332 buffer_free(&buffer); 333 close(fd); 334 return NULL; 335 } 336 337 /* Check that it is at least big enough to contain the ID string. */ 338 if (len < sizeof(authfile_id_string)) { 339 debug3("Not a RSA1 key file %.200s.", filename); 340 buffer_free(&buffer); 341 close(fd); 342 return NULL; 343 } 344 /* 345 * Make sure it begins with the id string. Consume the id string 346 * from the buffer. 347 */ 348 for (i = 0; i < sizeof(authfile_id_string); i++) 349 if (buffer_get_char(&buffer) != authfile_id_string[i]) { 350 debug3("Not a RSA1 key file %.200s.", filename); 351 buffer_free(&buffer); 352 close(fd); 353 return NULL; 354 } 355 356 /* Read cipher type. */ 357 cipher_type = buffer_get_char(&buffer); 358 (void) buffer_get_int(&buffer); /* Reserved data. */ 359 360 /* Read the public key from the buffer. */ 361 (void) buffer_get_int(&buffer); 362 prv = key_new_private(KEY_RSA1); 363 364 buffer_get_bignum(&buffer, prv->rsa->n); 365 buffer_get_bignum(&buffer, prv->rsa->e); 366 if (commentp) 367 *commentp = buffer_get_string(&buffer, NULL); 368 else 369 xfree(buffer_get_string(&buffer, NULL)); 370 371 /* Check that it is a supported cipher. */ 372 cipher = cipher_by_number(cipher_type); 373 if (cipher == NULL) { 374 debug("Unsupported cipher %d used in key file %.200s.", 375 cipher_type, filename); 376 buffer_free(&buffer); 377 goto fail; 378 } 379 /* Initialize space for decrypted data. */ 380 buffer_init(&decrypted); 381 cp = buffer_append_space(&decrypted, buffer_len(&buffer)); 382 383 /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */ 384 cipher_set_key_string(&ciphercontext, cipher, passphrase, 385 CIPHER_DECRYPT); 386 cipher_crypt(&ciphercontext, cp, 387 buffer_ptr(&buffer), buffer_len(&buffer)); 388 cipher_cleanup(&ciphercontext); 389 memset(&ciphercontext, 0, sizeof(ciphercontext)); 390 buffer_free(&buffer); 391 392 check1 = buffer_get_char(&decrypted); 393 check2 = buffer_get_char(&decrypted); 394 if (check1 != buffer_get_char(&decrypted) || 395 check2 != buffer_get_char(&decrypted)) { 396 if (strcmp(passphrase, "") != 0) 397 debug("Bad passphrase supplied for key file %.200s.", 398 filename); 399 /* Bad passphrase. */ 400 buffer_free(&decrypted); 401 goto fail; 402 } 403 /* Read the rest of the private key. */ 404 buffer_get_bignum(&decrypted, prv->rsa->d); 405 buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */ 406 /* in SSL and SSH v1 p and q are exchanged */ 407 buffer_get_bignum(&decrypted, prv->rsa->q); /* p */ 408 buffer_get_bignum(&decrypted, prv->rsa->p); /* q */ 409 410 /* calculate p-1 and q-1 */ 411 rsa_generate_additional_parameters(prv->rsa); 412 413 buffer_free(&decrypted); 414 close(fd); 415 return prv; 416 417 fail: 418 if (commentp) 419 xfree(*commentp); 420 close(fd); 421 key_free(prv); 422 return NULL; 423 } 424 425 Key * 426 key_load_private_pem(int fd, int type, const char *passphrase, 427 char **commentp) 428 { 429 FILE *fp; 430 EVP_PKEY *pk = NULL; 431 Key *prv = NULL; 432 char *name = "<no key>"; 433 434 fp = fdopen(fd, "r"); 435 if (fp == NULL) { 436 error("fdopen failed: %s", strerror(errno)); 437 close(fd); 438 return NULL; 439 } 440 pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase); 441 if (pk == NULL) { 442 debug("PEM_read_PrivateKey failed"); 443 (void)ERR_get_error(); 444 } else if (pk->type == EVP_PKEY_RSA && 445 (type == KEY_UNSPEC||type==KEY_RSA)) { 446 prv = key_new(KEY_UNSPEC); 447 prv->rsa = EVP_PKEY_get1_RSA(pk); 448 prv->type = KEY_RSA; 449 name = "rsa w/o comment"; 450 #ifdef DEBUG_PK 451 RSA_print_fp(stderr, prv->rsa, 8); 452 #endif 453 } else if (pk->type == EVP_PKEY_DSA && 454 (type == KEY_UNSPEC||type==KEY_DSA)) { 455 prv = key_new(KEY_UNSPEC); 456 prv->dsa = EVP_PKEY_get1_DSA(pk); 457 prv->type = KEY_DSA; 458 name = "dsa w/o comment"; 459 #ifdef DEBUG_PK 460 DSA_print_fp(stderr, prv->dsa, 8); 461 #endif 462 } else { 463 error("PEM_read_PrivateKey: mismatch or " 464 "unknown EVP_PKEY save_type %d", pk->save_type); 465 } 466 fclose(fp); 467 if (pk != NULL) 468 EVP_PKEY_free(pk); 469 if (prv != NULL && commentp) 470 *commentp = xstrdup(name); 471 debug("read PEM private key done: type %s", 472 prv ? key_type(prv) : "<unknown>"); 473 return prv; 474 } 475 476 static int 477 key_perm_ok(int fd, const char *filename) 478 { 479 struct stat st; 480 481 if (fstat(fd, &st) < 0) 482 return 0; 483 /* 484 * if a key owned by the user is accessed, then we check the 485 * permissions of the file. if the key owned by a different user, 486 * then we don't care. 487 */ 488 #ifdef HAVE_CYGWIN 489 if (check_ntsec(filename)) 490 #endif 491 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { 492 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 493 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); 494 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 495 error("Permissions 0%3.3o for '%s' are too open.", 496 st.st_mode & 0777, filename); 497 error("It is recommended that your private key files are NOT accessible by others."); 498 error("This private key will be ignored."); 499 return 0; 500 } 501 return 1; 502 } 503 504 Key * 505 key_load_private_type(int type, const char *filename, const char *passphrase, 506 char **commentp) 507 { 508 int fd; 509 510 fd = open(filename, O_RDONLY); 511 if (fd < 0) 512 return NULL; 513 if (!key_perm_ok(fd, filename)) { 514 error("bad permissions: ignore key: %s", filename); 515 close(fd); 516 return NULL; 517 } 518 switch (type) { 519 case KEY_RSA1: 520 return key_load_private_rsa1(fd, filename, passphrase, 521 commentp); 522 /* closes fd */ 523 break; 524 case KEY_DSA: 525 case KEY_RSA: 526 case KEY_UNSPEC: 527 return key_load_private_pem(fd, type, passphrase, commentp); 528 /* closes fd */ 529 break; 530 default: 531 close(fd); 532 break; 533 } 534 return NULL; 535 } 536 537 Key * 538 key_load_private(const char *filename, const char *passphrase, 539 char **commentp) 540 { 541 Key *pub, *prv; 542 int fd; 543 544 fd = open(filename, O_RDONLY); 545 if (fd < 0) 546 return NULL; 547 if (!key_perm_ok(fd, filename)) { 548 error("bad permissions: ignore key: %s", filename); 549 close(fd); 550 return NULL; 551 } 552 pub = key_load_public_rsa1(fd, filename, commentp); 553 lseek(fd, (off_t) 0, SEEK_SET); /* rewind */ 554 if (pub == NULL) { 555 /* closes fd */ 556 prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL); 557 /* use the filename as a comment for PEM */ 558 if (commentp && prv) 559 *commentp = xstrdup(filename); 560 } else { 561 /* it's a SSH v1 key if the public key part is readable */ 562 key_free(pub); 563 /* closes fd */ 564 prv = key_load_private_rsa1(fd, filename, passphrase, NULL); 565 } 566 return prv; 567 } 568 569 static int 570 key_try_load_public(Key *k, const char *filename, char **commentp) 571 { 572 FILE *f; 573 char line[4096]; 574 char *cp; 575 576 f = fopen(filename, "r"); 577 if (f != NULL) { 578 while (fgets(line, sizeof(line), f)) { 579 line[sizeof(line)-1] = '\0'; 580 cp = line; 581 switch (*cp) { 582 case '#': 583 case '\n': 584 case '\0': 585 continue; 586 } 587 /* Skip leading whitespace. */ 588 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 589 ; 590 if (*cp) { 591 if (key_read(k, &cp) == 1) { 592 if (commentp) 593 *commentp=xstrdup(filename); 594 fclose(f); 595 return 1; 596 } 597 } 598 } 599 fclose(f); 600 } 601 return 0; 602 } 603 604 /* load public key from ssh v1 private or any pubkey file */ 605 Key * 606 key_load_public(const char *filename, char **commentp) 607 { 608 Key *pub; 609 char file[MAXPATHLEN]; 610 611 pub = key_load_public_type(KEY_RSA1, filename, commentp); 612 if (pub != NULL) 613 return pub; 614 pub = key_new(KEY_UNSPEC); 615 if (key_try_load_public(pub, filename, commentp) == 1) 616 return pub; 617 if ((strlcpy(file, filename, sizeof file) < sizeof(file)) && 618 (strlcat(file, ".pub", sizeof file) < sizeof(file)) && 619 (key_try_load_public(pub, file, commentp) == 1)) 620 return pub; 621 key_free(pub); 622 return NULL; 623 } 624