1 /* $OpenBSD: authfile.c,v 1.130 2018/07/09 21:59:10 markus Exp $ */ 2 /* 3 * Copyright (c) 2000, 2013 Markus Friedl. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "includes.h" 27 28 #include <sys/types.h> 29 #include <sys/stat.h> 30 #include <sys/uio.h> 31 32 #include <errno.h> 33 #include <fcntl.h> 34 #include <stdio.h> 35 #include <stdarg.h> 36 #include <stdlib.h> 37 #include <string.h> 38 #include <unistd.h> 39 #include <limits.h> 40 41 #include "cipher.h" 42 #include "ssh.h" 43 #include "log.h" 44 #include "authfile.h" 45 #include "misc.h" 46 #include "atomicio.h" 47 #include "sshkey.h" 48 #include "sshbuf.h" 49 #include "ssherr.h" 50 #include "krl.h" 51 52 #define MAX_KEY_FILE_SIZE (1024 * 1024) 53 54 /* Save a key blob to a file */ 55 static int 56 sshkey_save_private_blob(struct sshbuf *keybuf, const char *filename) 57 { 58 int fd, oerrno; 59 60 if ((fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600)) < 0) 61 return SSH_ERR_SYSTEM_ERROR; 62 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(keybuf), 63 sshbuf_len(keybuf)) != sshbuf_len(keybuf)) { 64 oerrno = errno; 65 close(fd); 66 unlink(filename); 67 errno = oerrno; 68 return SSH_ERR_SYSTEM_ERROR; 69 } 70 close(fd); 71 return 0; 72 } 73 74 int 75 sshkey_save_private(struct sshkey *key, const char *filename, 76 const char *passphrase, const char *comment, 77 int force_new_format, const char *new_format_cipher, int new_format_rounds) 78 { 79 struct sshbuf *keyblob = NULL; 80 int r; 81 82 if ((keyblob = sshbuf_new()) == NULL) 83 return SSH_ERR_ALLOC_FAIL; 84 if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment, 85 force_new_format, new_format_cipher, new_format_rounds)) != 0) 86 goto out; 87 if ((r = sshkey_save_private_blob(keyblob, filename)) != 0) 88 goto out; 89 r = 0; 90 out: 91 sshbuf_free(keyblob); 92 return r; 93 } 94 95 /* Load a key from a fd into a buffer */ 96 int 97 sshkey_load_file(int fd, struct sshbuf *blob) 98 { 99 u_char buf[1024]; 100 size_t len; 101 struct stat st; 102 int r; 103 104 if (fstat(fd, &st) < 0) 105 return SSH_ERR_SYSTEM_ERROR; 106 if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 && 107 st.st_size > MAX_KEY_FILE_SIZE) 108 return SSH_ERR_INVALID_FORMAT; 109 for (;;) { 110 if ((len = atomicio(read, fd, buf, sizeof(buf))) == 0) { 111 if (errno == EPIPE) 112 break; 113 r = SSH_ERR_SYSTEM_ERROR; 114 goto out; 115 } 116 if ((r = sshbuf_put(blob, buf, len)) != 0) 117 goto out; 118 if (sshbuf_len(blob) > MAX_KEY_FILE_SIZE) { 119 r = SSH_ERR_INVALID_FORMAT; 120 goto out; 121 } 122 } 123 if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 && 124 st.st_size != (off_t)sshbuf_len(blob)) { 125 r = SSH_ERR_FILE_CHANGED; 126 goto out; 127 } 128 r = 0; 129 130 out: 131 explicit_bzero(buf, sizeof(buf)); 132 if (r != 0) 133 sshbuf_reset(blob); 134 return r; 135 } 136 137 138 /* XXX remove error() calls from here? */ 139 int 140 sshkey_perm_ok(int fd, const char *filename) 141 { 142 struct stat st; 143 144 if (fstat(fd, &st) < 0) 145 return SSH_ERR_SYSTEM_ERROR; 146 /* 147 * if a key owned by the user is accessed, then we check the 148 * permissions of the file. if the key owned by a different user, 149 * then we don't care. 150 */ 151 #ifdef HAVE_CYGWIN 152 if (check_ntsec(filename)) 153 #endif 154 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { 155 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 156 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); 157 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 158 error("Permissions 0%3.3o for '%s' are too open.", 159 (u_int)st.st_mode & 0777, filename); 160 error("It is required that your private key files are NOT accessible by others."); 161 error("This private key will be ignored."); 162 return SSH_ERR_KEY_BAD_PERMISSIONS; 163 } 164 return 0; 165 } 166 167 /* XXX kill perm_ok now that we have SSH_ERR_KEY_BAD_PERMISSIONS? */ 168 int 169 sshkey_load_private_type(int type, const char *filename, const char *passphrase, 170 struct sshkey **keyp, char **commentp, int *perm_ok) 171 { 172 int fd, r; 173 174 if (keyp != NULL) 175 *keyp = NULL; 176 if (commentp != NULL) 177 *commentp = NULL; 178 179 if ((fd = open(filename, O_RDONLY)) < 0) { 180 if (perm_ok != NULL) 181 *perm_ok = 0; 182 return SSH_ERR_SYSTEM_ERROR; 183 } 184 if (sshkey_perm_ok(fd, filename) != 0) { 185 if (perm_ok != NULL) 186 *perm_ok = 0; 187 r = SSH_ERR_KEY_BAD_PERMISSIONS; 188 goto out; 189 } 190 if (perm_ok != NULL) 191 *perm_ok = 1; 192 193 r = sshkey_load_private_type_fd(fd, type, passphrase, keyp, commentp); 194 if (r == 0 && keyp && *keyp) 195 r = sshkey_set_filename(*keyp, filename); 196 out: 197 close(fd); 198 return r; 199 } 200 201 int 202 sshkey_load_private_type_fd(int fd, int type, const char *passphrase, 203 struct sshkey **keyp, char **commentp) 204 { 205 struct sshbuf *buffer = NULL; 206 int r; 207 208 if (keyp != NULL) 209 *keyp = NULL; 210 if ((buffer = sshbuf_new()) == NULL) { 211 r = SSH_ERR_ALLOC_FAIL; 212 goto out; 213 } 214 if ((r = sshkey_load_file(fd, buffer)) != 0 || 215 (r = sshkey_parse_private_fileblob_type(buffer, type, 216 passphrase, keyp, commentp)) != 0) 217 goto out; 218 219 /* success */ 220 r = 0; 221 out: 222 sshbuf_free(buffer); 223 return r; 224 } 225 226 /* XXX this is almost identical to sshkey_load_private_type() */ 227 int 228 sshkey_load_private(const char *filename, const char *passphrase, 229 struct sshkey **keyp, char **commentp) 230 { 231 struct sshbuf *buffer = NULL; 232 int r, fd; 233 234 if (keyp != NULL) 235 *keyp = NULL; 236 if (commentp != NULL) 237 *commentp = NULL; 238 239 if ((fd = open(filename, O_RDONLY)) < 0) 240 return SSH_ERR_SYSTEM_ERROR; 241 if (sshkey_perm_ok(fd, filename) != 0) { 242 r = SSH_ERR_KEY_BAD_PERMISSIONS; 243 goto out; 244 } 245 246 if ((buffer = sshbuf_new()) == NULL) { 247 r = SSH_ERR_ALLOC_FAIL; 248 goto out; 249 } 250 if ((r = sshkey_load_file(fd, buffer)) != 0 || 251 (r = sshkey_parse_private_fileblob(buffer, passphrase, keyp, 252 commentp)) != 0) 253 goto out; 254 if (keyp && *keyp && 255 (r = sshkey_set_filename(*keyp, filename)) != 0) 256 goto out; 257 r = 0; 258 out: 259 close(fd); 260 sshbuf_free(buffer); 261 return r; 262 } 263 264 static int 265 sshkey_try_load_public(struct sshkey *k, const char *filename, char **commentp) 266 { 267 FILE *f; 268 char *line = NULL, *cp; 269 size_t linesize = 0; 270 int r; 271 272 if (commentp != NULL) 273 *commentp = NULL; 274 if ((f = fopen(filename, "r")) == NULL) 275 return SSH_ERR_SYSTEM_ERROR; 276 while (getline(&line, &linesize, f) != -1) { 277 cp = line; 278 switch (*cp) { 279 case '#': 280 case '\n': 281 case '\0': 282 continue; 283 } 284 /* Abort loading if this looks like a private key */ 285 if (strncmp(cp, "-----BEGIN", 10) == 0 || 286 strcmp(cp, "SSH PRIVATE KEY FILE") == 0) 287 break; 288 /* Skip leading whitespace. */ 289 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 290 ; 291 if (*cp) { 292 if ((r = sshkey_read(k, &cp)) == 0) { 293 cp[strcspn(cp, "\r\n")] = '\0'; 294 if (commentp) { 295 *commentp = strdup(*cp ? 296 cp : filename); 297 if (*commentp == NULL) 298 r = SSH_ERR_ALLOC_FAIL; 299 } 300 free(line); 301 fclose(f); 302 return r; 303 } 304 } 305 } 306 free(line); 307 fclose(f); 308 return SSH_ERR_INVALID_FORMAT; 309 } 310 311 /* load public key from any pubkey file */ 312 int 313 sshkey_load_public(const char *filename, struct sshkey **keyp, char **commentp) 314 { 315 struct sshkey *pub = NULL; 316 char *file = NULL; 317 int r; 318 319 if (keyp != NULL) 320 *keyp = NULL; 321 if (commentp != NULL) 322 *commentp = NULL; 323 324 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) 325 return SSH_ERR_ALLOC_FAIL; 326 if ((r = sshkey_try_load_public(pub, filename, commentp)) == 0) { 327 if (keyp != NULL) { 328 *keyp = pub; 329 pub = NULL; 330 } 331 r = 0; 332 goto out; 333 } 334 sshkey_free(pub); 335 336 /* try .pub suffix */ 337 if (asprintf(&file, "%s.pub", filename) == -1) 338 return SSH_ERR_ALLOC_FAIL; 339 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 340 r = SSH_ERR_ALLOC_FAIL; 341 goto out; 342 } 343 if ((r = sshkey_try_load_public(pub, file, commentp)) == 0) { 344 if (keyp != NULL) { 345 *keyp = pub; 346 pub = NULL; 347 } 348 r = 0; 349 } 350 out: 351 free(file); 352 sshkey_free(pub); 353 return r; 354 } 355 356 /* Load the certificate associated with the named private key */ 357 int 358 sshkey_load_cert(const char *filename, struct sshkey **keyp) 359 { 360 struct sshkey *pub = NULL; 361 char *file = NULL; 362 int r = SSH_ERR_INTERNAL_ERROR; 363 364 if (keyp != NULL) 365 *keyp = NULL; 366 367 if (asprintf(&file, "%s-cert.pub", filename) == -1) 368 return SSH_ERR_ALLOC_FAIL; 369 370 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 371 goto out; 372 } 373 if ((r = sshkey_try_load_public(pub, file, NULL)) != 0) 374 goto out; 375 /* success */ 376 if (keyp != NULL) { 377 *keyp = pub; 378 pub = NULL; 379 } 380 r = 0; 381 out: 382 free(file); 383 sshkey_free(pub); 384 return r; 385 } 386 387 /* Load private key and certificate */ 388 int 389 sshkey_load_private_cert(int type, const char *filename, const char *passphrase, 390 struct sshkey **keyp, int *perm_ok) 391 { 392 struct sshkey *key = NULL, *cert = NULL; 393 int r; 394 395 if (keyp != NULL) 396 *keyp = NULL; 397 398 switch (type) { 399 #ifdef WITH_OPENSSL 400 case KEY_RSA: 401 case KEY_DSA: 402 case KEY_ECDSA: 403 #endif /* WITH_OPENSSL */ 404 case KEY_ED25519: 405 case KEY_XMSS: 406 case KEY_UNSPEC: 407 break; 408 default: 409 return SSH_ERR_KEY_TYPE_UNKNOWN; 410 } 411 412 if ((r = sshkey_load_private_type(type, filename, 413 passphrase, &key, NULL, perm_ok)) != 0 || 414 (r = sshkey_load_cert(filename, &cert)) != 0) 415 goto out; 416 417 /* Make sure the private key matches the certificate */ 418 if (sshkey_equal_public(key, cert) == 0) { 419 r = SSH_ERR_KEY_CERT_MISMATCH; 420 goto out; 421 } 422 423 if ((r = sshkey_to_certified(key)) != 0 || 424 (r = sshkey_cert_copy(cert, key)) != 0) 425 goto out; 426 r = 0; 427 if (keyp != NULL) { 428 *keyp = key; 429 key = NULL; 430 } 431 out: 432 sshkey_free(key); 433 sshkey_free(cert); 434 return r; 435 } 436 437 /* 438 * Returns success if the specified "key" is listed in the file "filename", 439 * SSH_ERR_KEY_NOT_FOUND: if the key is not listed or another error. 440 * If "strict_type" is set then the key type must match exactly, 441 * otherwise a comparison that ignores certficiate data is performed. 442 * If "check_ca" is set and "key" is a certificate, then its CA key is 443 * also checked and sshkey_in_file() will return success if either is found. 444 */ 445 int 446 sshkey_in_file(struct sshkey *key, const char *filename, int strict_type, 447 int check_ca) 448 { 449 FILE *f; 450 char *line = NULL, *cp; 451 size_t linesize = 0; 452 int r = 0; 453 struct sshkey *pub = NULL; 454 455 int (*sshkey_compare)(const struct sshkey *, const struct sshkey *) = 456 strict_type ? sshkey_equal : sshkey_equal_public; 457 458 if ((f = fopen(filename, "r")) == NULL) 459 return SSH_ERR_SYSTEM_ERROR; 460 461 while (getline(&line, &linesize, f) != -1) { 462 cp = line; 463 464 /* Skip leading whitespace. */ 465 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 466 ; 467 468 /* Skip comments and empty lines */ 469 switch (*cp) { 470 case '#': 471 case '\n': 472 case '\0': 473 continue; 474 } 475 476 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 477 r = SSH_ERR_ALLOC_FAIL; 478 goto out; 479 } 480 if ((r = sshkey_read(pub, &cp)) != 0) 481 goto out; 482 if (sshkey_compare(key, pub) || 483 (check_ca && sshkey_is_cert(key) && 484 sshkey_compare(key->cert->signature_key, pub))) { 485 r = 0; 486 goto out; 487 } 488 sshkey_free(pub); 489 pub = NULL; 490 } 491 r = SSH_ERR_KEY_NOT_FOUND; 492 out: 493 free(line); 494 sshkey_free(pub); 495 fclose(f); 496 return r; 497 } 498 499 /* 500 * Checks whether the specified key is revoked, returning 0 if not, 501 * SSH_ERR_KEY_REVOKED if it is or another error code if something 502 * unexpected happened. 503 * This will check both the key and, if it is a certificate, its CA key too. 504 * "revoked_keys_file" may be a KRL or a one-per-line list of public keys. 505 */ 506 int 507 sshkey_check_revoked(struct sshkey *key, const char *revoked_keys_file) 508 { 509 int r; 510 511 r = ssh_krl_file_contains_key(revoked_keys_file, key); 512 /* If this was not a KRL to begin with then continue below */ 513 if (r != SSH_ERR_KRL_BAD_MAGIC) 514 return r; 515 516 /* 517 * If the file is not a KRL or we can't handle KRLs then attempt to 518 * parse the file as a flat list of keys. 519 */ 520 switch ((r = sshkey_in_file(key, revoked_keys_file, 0, 1))) { 521 case 0: 522 /* Key found => revoked */ 523 return SSH_ERR_KEY_REVOKED; 524 case SSH_ERR_KEY_NOT_FOUND: 525 /* Key not found => not revoked */ 526 return 0; 527 default: 528 /* Some other error occurred */ 529 return r; 530 } 531 } 532 533