1 /* $OpenBSD: authfile.c,v 1.76 2006/08/03 03:34:41 deraadt Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This file contains functions for reading and writing identity files, and 7 * for reading the passphrase from the user. 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 * 15 * 16 * Copyright (c) 2000 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include "includes.h" 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 #include <sys/param.h> 44 #include <sys/uio.h> 45 46 #include <openssl/err.h> 47 #include <openssl/evp.h> 48 #include <openssl/pem.h> 49 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <stdarg.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <unistd.h> 57 58 #include "xmalloc.h" 59 #include "cipher.h" 60 #include "buffer.h" 61 #include "key.h" 62 #include "ssh.h" 63 #include "log.h" 64 #include "authfile.h" 65 #include "rsa.h" 66 #include "misc.h" 67 #include "atomicio.h" 68 #include "pathnames.h" 69 70 /* Version identification string for SSH v1 identity files. */ 71 static const char authfile_id_string[] = 72 "SSH PRIVATE KEY FILE FORMAT 1.1\n"; 73 74 /* 75 * Saves the authentication (private) key in a file, encrypting it with 76 * passphrase. The identification of the file (lowest 64 bits of n) will 77 * precede the key to provide identification of the key without needing a 78 * passphrase. 79 */ 80 81 static int 82 key_save_private_rsa1(Key *key, const char *filename, const char *passphrase, 83 const char *comment) 84 { 85 Buffer buffer, encrypted; 86 u_char buf[100], *cp; 87 int fd, i, cipher_num; 88 CipherContext ciphercontext; 89 Cipher *cipher; 90 u_int32_t rnd; 91 92 /* 93 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting 94 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER. 95 */ 96 cipher_num = (strcmp(passphrase, "") == 0) ? 97 SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER; 98 if ((cipher = cipher_by_number(cipher_num)) == NULL) 99 fatal("save_private_key_rsa: bad cipher"); 100 101 /* This buffer is used to built the secret part of the private key. */ 102 buffer_init(&buffer); 103 104 /* Put checkbytes for checking passphrase validity. */ 105 rnd = arc4random(); 106 buf[0] = rnd & 0xff; 107 buf[1] = (rnd >> 8) & 0xff; 108 buf[2] = buf[0]; 109 buf[3] = buf[1]; 110 buffer_append(&buffer, buf, 4); 111 112 /* 113 * Store the private key (n and e will not be stored because they 114 * will be stored in plain text, and storing them also in encrypted 115 * format would just give known plaintext). 116 */ 117 buffer_put_bignum(&buffer, key->rsa->d); 118 buffer_put_bignum(&buffer, key->rsa->iqmp); 119 buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */ 120 buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */ 121 122 /* Pad the part to be encrypted until its size is a multiple of 8. */ 123 while (buffer_len(&buffer) % 8 != 0) 124 buffer_put_char(&buffer, 0); 125 126 /* This buffer will be used to contain the data in the file. */ 127 buffer_init(&encrypted); 128 129 /* First store keyfile id string. */ 130 for (i = 0; authfile_id_string[i]; i++) 131 buffer_put_char(&encrypted, authfile_id_string[i]); 132 buffer_put_char(&encrypted, 0); 133 134 /* Store cipher type. */ 135 buffer_put_char(&encrypted, cipher_num); 136 buffer_put_int(&encrypted, 0); /* For future extension */ 137 138 /* Store public key. This will be in plain text. */ 139 buffer_put_int(&encrypted, BN_num_bits(key->rsa->n)); 140 buffer_put_bignum(&encrypted, key->rsa->n); 141 buffer_put_bignum(&encrypted, key->rsa->e); 142 buffer_put_cstring(&encrypted, comment); 143 144 /* Allocate space for the private part of the key in the buffer. */ 145 cp = buffer_append_space(&encrypted, buffer_len(&buffer)); 146 147 cipher_set_key_string(&ciphercontext, cipher, passphrase, 148 CIPHER_ENCRYPT); 149 cipher_crypt(&ciphercontext, cp, 150 buffer_ptr(&buffer), buffer_len(&buffer)); 151 cipher_cleanup(&ciphercontext); 152 memset(&ciphercontext, 0, sizeof(ciphercontext)); 153 154 /* Destroy temporary data. */ 155 memset(buf, 0, sizeof(buf)); 156 buffer_free(&buffer); 157 158 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600); 159 if (fd < 0) { 160 error("open %s failed: %s.", filename, strerror(errno)); 161 buffer_free(&encrypted); 162 return 0; 163 } 164 if (atomicio(vwrite, fd, buffer_ptr(&encrypted), 165 buffer_len(&encrypted)) != buffer_len(&encrypted)) { 166 error("write to key file %s failed: %s", filename, 167 strerror(errno)); 168 buffer_free(&encrypted); 169 close(fd); 170 unlink(filename); 171 return 0; 172 } 173 close(fd); 174 buffer_free(&encrypted); 175 return 1; 176 } 177 178 /* save SSH v2 key in OpenSSL PEM format */ 179 static int 180 key_save_private_pem(Key *key, const char *filename, const char *_passphrase, 181 const char *comment) 182 { 183 FILE *fp; 184 int fd; 185 int success = 0; 186 int len = strlen(_passphrase); 187 u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL; 188 const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL; 189 190 if (len > 0 && len <= 4) { 191 error("passphrase too short: have %d bytes, need > 4", len); 192 return 0; 193 } 194 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600); 195 if (fd < 0) { 196 error("open %s failed: %s.", filename, strerror(errno)); 197 return 0; 198 } 199 fp = fdopen(fd, "w"); 200 if (fp == NULL) { 201 error("fdopen %s failed: %s.", filename, strerror(errno)); 202 close(fd); 203 return 0; 204 } 205 switch (key->type) { 206 case KEY_DSA: 207 success = PEM_write_DSAPrivateKey(fp, key->dsa, 208 cipher, passphrase, len, NULL, NULL); 209 break; 210 case KEY_RSA: 211 success = PEM_write_RSAPrivateKey(fp, key->rsa, 212 cipher, passphrase, len, NULL, NULL); 213 break; 214 } 215 fclose(fp); 216 return success; 217 } 218 219 int 220 key_save_private(Key *key, const char *filename, const char *passphrase, 221 const char *comment) 222 { 223 switch (key->type) { 224 case KEY_RSA1: 225 return key_save_private_rsa1(key, filename, passphrase, 226 comment); 227 case KEY_DSA: 228 case KEY_RSA: 229 return key_save_private_pem(key, filename, passphrase, 230 comment); 231 default: 232 break; 233 } 234 error("key_save_private: cannot save key type %d", key->type); 235 return 0; 236 } 237 238 /* 239 * Loads the public part of the ssh v1 key file. Returns NULL if an error was 240 * encountered (the file does not exist or is not readable), and the key 241 * otherwise. 242 */ 243 244 static Key * 245 key_load_public_rsa1(int fd, const char *filename, char **commentp) 246 { 247 Buffer buffer; 248 Key *pub; 249 struct stat st; 250 char *cp; 251 u_int i; 252 size_t len; 253 254 if (fstat(fd, &st) < 0) { 255 error("fstat for key file %.200s failed: %.100s", 256 filename, strerror(errno)); 257 return NULL; 258 } 259 if (st.st_size > 1*1024*1024) { 260 error("key file %.200s too large", filename); 261 return NULL; 262 } 263 len = (size_t)st.st_size; /* truncated */ 264 265 buffer_init(&buffer); 266 cp = buffer_append_space(&buffer, len); 267 268 if (atomicio(read, fd, cp, len) != len) { 269 debug("Read from key file %.200s failed: %.100s", filename, 270 strerror(errno)); 271 buffer_free(&buffer); 272 return NULL; 273 } 274 275 /* Check that it is at least big enough to contain the ID string. */ 276 if (len < sizeof(authfile_id_string)) { 277 debug3("Not a RSA1 key file %.200s.", filename); 278 buffer_free(&buffer); 279 return NULL; 280 } 281 /* 282 * Make sure it begins with the id string. Consume the id string 283 * from the buffer. 284 */ 285 for (i = 0; i < sizeof(authfile_id_string); i++) 286 if (buffer_get_char(&buffer) != authfile_id_string[i]) { 287 debug3("Not a RSA1 key file %.200s.", filename); 288 buffer_free(&buffer); 289 return NULL; 290 } 291 /* Skip cipher type and reserved data. */ 292 (void) buffer_get_char(&buffer); /* cipher type */ 293 (void) buffer_get_int(&buffer); /* reserved */ 294 295 /* Read the public key from the buffer. */ 296 (void) buffer_get_int(&buffer); 297 pub = key_new(KEY_RSA1); 298 buffer_get_bignum(&buffer, pub->rsa->n); 299 buffer_get_bignum(&buffer, pub->rsa->e); 300 if (commentp) 301 *commentp = buffer_get_string(&buffer, NULL); 302 /* The encrypted private part is not parsed by this function. */ 303 304 buffer_free(&buffer); 305 return pub; 306 } 307 308 /* load public key from private-key file, works only for SSH v1 */ 309 Key * 310 key_load_public_type(int type, const char *filename, char **commentp) 311 { 312 Key *pub; 313 int fd; 314 315 if (type == KEY_RSA1) { 316 fd = open(filename, O_RDONLY); 317 if (fd < 0) 318 return NULL; 319 pub = key_load_public_rsa1(fd, filename, commentp); 320 close(fd); 321 return pub; 322 } 323 return NULL; 324 } 325 326 /* 327 * Loads the private key from the file. Returns 0 if an error is encountered 328 * (file does not exist or is not readable, or passphrase is bad). This 329 * initializes the private key. 330 * Assumes we are called under uid of the owner of the file. 331 */ 332 333 static Key * 334 key_load_private_rsa1(int fd, const char *filename, const char *passphrase, 335 char **commentp) 336 { 337 u_int i; 338 int check1, check2, cipher_type; 339 size_t len; 340 Buffer buffer, decrypted; 341 u_char *cp; 342 CipherContext ciphercontext; 343 Cipher *cipher; 344 Key *prv = NULL; 345 struct stat st; 346 347 if (fstat(fd, &st) < 0) { 348 error("fstat for key file %.200s failed: %.100s", 349 filename, strerror(errno)); 350 close(fd); 351 return NULL; 352 } 353 if (st.st_size > 1*1024*1024) { 354 error("key file %.200s too large", filename); 355 close(fd); 356 return (NULL); 357 } 358 len = (size_t)st.st_size; /* truncated */ 359 360 buffer_init(&buffer); 361 cp = buffer_append_space(&buffer, len); 362 363 if (atomicio(read, fd, cp, len) != len) { 364 debug("Read from key file %.200s failed: %.100s", filename, 365 strerror(errno)); 366 buffer_free(&buffer); 367 close(fd); 368 return NULL; 369 } 370 371 /* Check that it is at least big enough to contain the ID string. */ 372 if (len < sizeof(authfile_id_string)) { 373 debug3("Not a RSA1 key file %.200s.", filename); 374 buffer_free(&buffer); 375 close(fd); 376 return NULL; 377 } 378 /* 379 * Make sure it begins with the id string. Consume the id string 380 * from the buffer. 381 */ 382 for (i = 0; i < sizeof(authfile_id_string); i++) 383 if (buffer_get_char(&buffer) != authfile_id_string[i]) { 384 debug3("Not a RSA1 key file %.200s.", filename); 385 buffer_free(&buffer); 386 close(fd); 387 return NULL; 388 } 389 390 /* Read cipher type. */ 391 cipher_type = buffer_get_char(&buffer); 392 (void) buffer_get_int(&buffer); /* Reserved data. */ 393 394 /* Read the public key from the buffer. */ 395 (void) buffer_get_int(&buffer); 396 prv = key_new_private(KEY_RSA1); 397 398 buffer_get_bignum(&buffer, prv->rsa->n); 399 buffer_get_bignum(&buffer, prv->rsa->e); 400 if (commentp) 401 *commentp = buffer_get_string(&buffer, NULL); 402 else 403 xfree(buffer_get_string(&buffer, NULL)); 404 405 /* Check that it is a supported cipher. */ 406 cipher = cipher_by_number(cipher_type); 407 if (cipher == NULL) { 408 debug("Unsupported cipher %d used in key file %.200s.", 409 cipher_type, filename); 410 buffer_free(&buffer); 411 goto fail; 412 } 413 /* Initialize space for decrypted data. */ 414 buffer_init(&decrypted); 415 cp = buffer_append_space(&decrypted, buffer_len(&buffer)); 416 417 /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */ 418 cipher_set_key_string(&ciphercontext, cipher, passphrase, 419 CIPHER_DECRYPT); 420 cipher_crypt(&ciphercontext, cp, 421 buffer_ptr(&buffer), buffer_len(&buffer)); 422 cipher_cleanup(&ciphercontext); 423 memset(&ciphercontext, 0, sizeof(ciphercontext)); 424 buffer_free(&buffer); 425 426 check1 = buffer_get_char(&decrypted); 427 check2 = buffer_get_char(&decrypted); 428 if (check1 != buffer_get_char(&decrypted) || 429 check2 != buffer_get_char(&decrypted)) { 430 if (strcmp(passphrase, "") != 0) 431 debug("Bad passphrase supplied for key file %.200s.", 432 filename); 433 /* Bad passphrase. */ 434 buffer_free(&decrypted); 435 goto fail; 436 } 437 /* Read the rest of the private key. */ 438 buffer_get_bignum(&decrypted, prv->rsa->d); 439 buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */ 440 /* in SSL and SSH v1 p and q are exchanged */ 441 buffer_get_bignum(&decrypted, prv->rsa->q); /* p */ 442 buffer_get_bignum(&decrypted, prv->rsa->p); /* q */ 443 444 /* calculate p-1 and q-1 */ 445 rsa_generate_additional_parameters(prv->rsa); 446 447 buffer_free(&decrypted); 448 449 /* enable blinding */ 450 if (RSA_blinding_on(prv->rsa, NULL) != 1) { 451 error("key_load_private_rsa1: RSA_blinding_on failed"); 452 goto fail; 453 } 454 close(fd); 455 return prv; 456 457 fail: 458 if (commentp) 459 xfree(*commentp); 460 close(fd); 461 key_free(prv); 462 return NULL; 463 } 464 465 Key * 466 key_load_private_pem(int fd, int type, const char *passphrase, 467 char **commentp) 468 { 469 FILE *fp; 470 EVP_PKEY *pk = NULL; 471 Key *prv = NULL; 472 char *name = "<no key>"; 473 474 fp = fdopen(fd, "r"); 475 if (fp == NULL) { 476 error("fdopen failed: %s", strerror(errno)); 477 close(fd); 478 return NULL; 479 } 480 pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase); 481 if (pk == NULL) { 482 debug("PEM_read_PrivateKey failed"); 483 (void)ERR_get_error(); 484 } else if (pk->type == EVP_PKEY_RSA && 485 (type == KEY_UNSPEC||type==KEY_RSA)) { 486 prv = key_new(KEY_UNSPEC); 487 prv->rsa = EVP_PKEY_get1_RSA(pk); 488 prv->type = KEY_RSA; 489 name = "rsa w/o comment"; 490 #ifdef DEBUG_PK 491 RSA_print_fp(stderr, prv->rsa, 8); 492 #endif 493 if (RSA_blinding_on(prv->rsa, NULL) != 1) { 494 error("key_load_private_pem: RSA_blinding_on failed"); 495 key_free(prv); 496 prv = NULL; 497 } 498 } else if (pk->type == EVP_PKEY_DSA && 499 (type == KEY_UNSPEC||type==KEY_DSA)) { 500 prv = key_new(KEY_UNSPEC); 501 prv->dsa = EVP_PKEY_get1_DSA(pk); 502 prv->type = KEY_DSA; 503 name = "dsa w/o comment"; 504 #ifdef DEBUG_PK 505 DSA_print_fp(stderr, prv->dsa, 8); 506 #endif 507 } else { 508 error("PEM_read_PrivateKey: mismatch or " 509 "unknown EVP_PKEY save_type %d", pk->save_type); 510 } 511 fclose(fp); 512 if (pk != NULL) 513 EVP_PKEY_free(pk); 514 if (prv != NULL && commentp) 515 *commentp = xstrdup(name); 516 debug("read PEM private key done: type %s", 517 prv ? key_type(prv) : "<unknown>"); 518 return prv; 519 } 520 521 int 522 key_perm_ok(int fd, const char *filename) 523 { 524 struct stat st; 525 526 if (fstat(fd, &st) < 0) 527 return 0; 528 /* 529 * if a key owned by the user is accessed, then we check the 530 * permissions of the file. if the key owned by a different user, 531 * then we don't care. 532 */ 533 #ifdef HAVE_CYGWIN 534 if (check_ntsec(filename)) 535 #endif 536 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { 537 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 538 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); 539 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 540 error("Permissions 0%3.3o for '%s' are too open.", 541 (u_int)st.st_mode & 0777, filename); 542 error("It is recommended that your private key files are NOT accessible by others."); 543 error("This private key will be ignored."); 544 return 0; 545 } 546 return 1; 547 } 548 549 Key * 550 key_load_private_type(int type, const char *filename, const char *passphrase, 551 char **commentp, int *perm_ok) 552 { 553 int fd; 554 555 fd = open(filename, O_RDONLY); 556 if (fd < 0) 557 return NULL; 558 if (!key_perm_ok(fd, filename)) { 559 if (perm_ok != NULL) 560 *perm_ok = 0; 561 error("bad permissions: ignore key: %s", filename); 562 close(fd); 563 return NULL; 564 } 565 if (perm_ok != NULL) 566 *perm_ok = 1; 567 switch (type) { 568 case KEY_RSA1: 569 return key_load_private_rsa1(fd, filename, passphrase, 570 commentp); 571 /* closes fd */ 572 case KEY_DSA: 573 case KEY_RSA: 574 case KEY_UNSPEC: 575 return key_load_private_pem(fd, type, passphrase, commentp); 576 /* closes fd */ 577 default: 578 close(fd); 579 break; 580 } 581 return NULL; 582 } 583 584 Key * 585 key_load_private(const char *filename, const char *passphrase, 586 char **commentp) 587 { 588 Key *pub, *prv; 589 int fd; 590 591 fd = open(filename, O_RDONLY); 592 if (fd < 0) 593 return NULL; 594 if (!key_perm_ok(fd, filename)) { 595 error("bad permissions: ignore key: %s", filename); 596 close(fd); 597 return NULL; 598 } 599 pub = key_load_public_rsa1(fd, filename, commentp); 600 lseek(fd, (off_t) 0, SEEK_SET); /* rewind */ 601 if (pub == NULL) { 602 /* closes fd */ 603 prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL); 604 /* use the filename as a comment for PEM */ 605 if (commentp && prv) 606 *commentp = xstrdup(filename); 607 } else { 608 /* it's a SSH v1 key if the public key part is readable */ 609 key_free(pub); 610 /* closes fd */ 611 prv = key_load_private_rsa1(fd, filename, passphrase, NULL); 612 } 613 return prv; 614 } 615 616 static int 617 key_try_load_public(Key *k, const char *filename, char **commentp) 618 { 619 FILE *f; 620 char line[SSH_MAX_PUBKEY_BYTES]; 621 char *cp; 622 u_long linenum = 0; 623 624 f = fopen(filename, "r"); 625 if (f != NULL) { 626 while (read_keyfile_line(f, filename, line, sizeof(line), 627 &linenum) != -1) { 628 cp = line; 629 switch (*cp) { 630 case '#': 631 case '\n': 632 case '\0': 633 continue; 634 } 635 /* Skip leading whitespace. */ 636 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 637 ; 638 if (*cp) { 639 if (key_read(k, &cp) == 1) { 640 if (commentp) 641 *commentp=xstrdup(filename); 642 fclose(f); 643 return 1; 644 } 645 } 646 } 647 fclose(f); 648 } 649 return 0; 650 } 651 652 /* load public key from ssh v1 private or any pubkey file */ 653 Key * 654 key_load_public(const char *filename, char **commentp) 655 { 656 Key *pub; 657 char file[MAXPATHLEN]; 658 659 /* try rsa1 private key */ 660 pub = key_load_public_type(KEY_RSA1, filename, commentp); 661 if (pub != NULL) 662 return pub; 663 664 /* try rsa1 public key */ 665 pub = key_new(KEY_RSA1); 666 if (key_try_load_public(pub, filename, commentp) == 1) 667 return pub; 668 key_free(pub); 669 670 /* try ssh2 public key */ 671 pub = key_new(KEY_UNSPEC); 672 if (key_try_load_public(pub, filename, commentp) == 1) 673 return pub; 674 if ((strlcpy(file, filename, sizeof file) < sizeof(file)) && 675 (strlcat(file, ".pub", sizeof file) < sizeof(file)) && 676 (key_try_load_public(pub, file, commentp) == 1)) 677 return pub; 678 key_free(pub); 679 return NULL; 680 } 681 682 char * 683 blacklist_filename(const Key *key) 684 { 685 char *name; 686 687 xasprintf(&name, "%s.%s-%u", 688 _PATH_BLACKLIST, key_type(key), key_size(key)); 689 return name; 690 } 691 692 /* Scan a blacklist of known-vulnerable keys. */ 693 int 694 blacklisted_key(const Key *key) 695 { 696 char *blacklist_file; 697 int fd = -1; 698 char *dgst_hex = NULL; 699 char *dgst_packed = NULL, *p; 700 int i; 701 size_t line_len; 702 struct stat st; 703 char buf[256]; 704 off_t start, lower, upper; 705 int ret = 0; 706 707 blacklist_file = blacklist_filename(key); 708 debug("Checking blacklist file %s", blacklist_file); 709 fd = open(blacklist_file, O_RDONLY); 710 if (fd < 0) 711 goto out; 712 713 dgst_hex = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 714 /* Remove all colons */ 715 dgst_packed = xcalloc(1, strlen(dgst_hex) + 1); 716 for (i = 0, p = dgst_packed; dgst_hex[i]; i++) 717 if (dgst_hex[i] != ':') 718 *p++ = dgst_hex[i]; 719 /* Only compare least-significant 80 bits (to keep the blacklist 720 * size down) 721 */ 722 line_len = strlen(dgst_packed + 12); 723 if (line_len > 32) 724 goto out; 725 726 /* Skip leading comments */ 727 start = 0; 728 for (;;) { 729 ssize_t r; 730 char *newline; 731 732 r = atomicio(read, fd, buf, 256); 733 if (r <= 0) 734 goto out; 735 if (buf[0] != '#') 736 break; 737 738 newline = memchr(buf, '\n', 256); 739 if (!newline) 740 goto out; 741 start += newline + 1 - buf; 742 if (lseek(fd, start, SEEK_SET) < 0) 743 goto out; 744 } 745 746 /* Initialise binary search record numbers */ 747 if (fstat(fd, &st) < 0) 748 goto out; 749 lower = 0; 750 upper = (st.st_size - start) / (line_len + 1); 751 752 while (lower != upper) { 753 off_t cur; 754 char buf[32]; 755 int cmp; 756 757 cur = lower + (upper - lower) / 2; 758 759 /* Read this line and compare to digest; this is 760 * overflow-safe since cur < max(off_t) / (line_len + 1) */ 761 if (lseek(fd, start + cur * (line_len + 1), SEEK_SET) < 0) 762 break; 763 if (atomicio(read, fd, buf, line_len) != line_len) 764 break; 765 cmp = memcmp(buf, dgst_packed + 12, line_len); 766 if (cmp < 0) { 767 if (cur == lower) 768 break; 769 lower = cur; 770 } else if (cmp > 0) { 771 if (cur == upper) 772 break; 773 upper = cur; 774 } else { 775 debug("Found %s in blacklist", dgst_hex); 776 ret = 1; 777 break; 778 } 779 } 780 781 out: 782 if (dgst_packed) 783 xfree(dgst_packed); 784 if (dgst_hex) 785 xfree(dgst_hex); 786 if (fd >= 0) 787 close(fd); 788 xfree(blacklist_file); 789 return ret; 790 } 791