1 /* $OpenBSD: authfile.c,v 1.137 2020/01/25 23:02:13 djm 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 27 #include <sys/types.h> 28 #include <sys/stat.h> 29 #include <sys/uio.h> 30 31 #include <errno.h> 32 #include <fcntl.h> 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 #include <unistd.h> 37 #include <limits.h> 38 39 #include "cipher.h" 40 #include "ssh.h" 41 #include "log.h" 42 #include "authfile.h" 43 #include "misc.h" 44 #include "atomicio.h" 45 #include "sshkey.h" 46 #include "sshbuf.h" 47 #include "ssherr.h" 48 #include "krl.h" 49 50 #define MAX_KEY_FILE_SIZE (1024 * 1024) 51 52 /* Save a key blob to a file */ 53 static int 54 sshkey_save_private_blob(struct sshbuf *keybuf, const char *filename) 55 { 56 int r; 57 mode_t omask; 58 59 omask = umask(077); 60 r = sshbuf_write_file(filename, keybuf); 61 umask(omask); 62 return r; 63 } 64 65 int 66 sshkey_save_private(struct sshkey *key, const char *filename, 67 const char *passphrase, const char *comment, 68 int format, const char *openssh_format_cipher, int openssh_format_rounds) 69 { 70 struct sshbuf *keyblob = NULL; 71 int r; 72 73 if ((keyblob = sshbuf_new()) == NULL) 74 return SSH_ERR_ALLOC_FAIL; 75 if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment, 76 format, openssh_format_cipher, openssh_format_rounds)) != 0) 77 goto out; 78 if ((r = sshkey_save_private_blob(keyblob, filename)) != 0) 79 goto out; 80 r = 0; 81 out: 82 sshbuf_free(keyblob); 83 return r; 84 } 85 86 /* XXX remove error() calls from here? */ 87 int 88 sshkey_perm_ok(int fd, const char *filename) 89 { 90 struct stat st; 91 92 if (fstat(fd, &st) == -1) 93 return SSH_ERR_SYSTEM_ERROR; 94 /* 95 * if a key owned by the user is accessed, then we check the 96 * permissions of the file. if the key owned by a different user, 97 * then we don't care. 98 */ 99 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { 100 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 101 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); 102 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 103 error("Permissions 0%3.3o for '%s' are too open.", 104 (u_int)st.st_mode & 0777, filename); 105 error("It is required that your private key files are NOT accessible by others."); 106 error("This private key will be ignored."); 107 return SSH_ERR_KEY_BAD_PERMISSIONS; 108 } 109 return 0; 110 } 111 112 int 113 sshkey_load_private_type(int type, const char *filename, const char *passphrase, 114 struct sshkey **keyp, char **commentp) 115 { 116 int fd, r; 117 118 if (keyp != NULL) 119 *keyp = NULL; 120 if (commentp != NULL) 121 *commentp = NULL; 122 123 if ((fd = open(filename, O_RDONLY)) == -1) 124 return SSH_ERR_SYSTEM_ERROR; 125 126 r = sshkey_perm_ok(fd, filename); 127 if (r != 0) 128 goto out; 129 130 r = sshkey_load_private_type_fd(fd, type, passphrase, keyp, commentp); 131 if (r == 0 && keyp && *keyp) 132 r = sshkey_set_filename(*keyp, filename); 133 out: 134 close(fd); 135 return r; 136 } 137 138 int 139 sshkey_load_private_type_fd(int fd, int type, const char *passphrase, 140 struct sshkey **keyp, char **commentp) 141 { 142 struct sshbuf *buffer = NULL; 143 int r; 144 145 if (keyp != NULL) 146 *keyp = NULL; 147 if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || 148 (r = sshkey_parse_private_fileblob_type(buffer, type, 149 passphrase, keyp, commentp)) != 0) 150 goto out; 151 152 /* success */ 153 r = 0; 154 out: 155 sshbuf_free(buffer); 156 return r; 157 } 158 159 /* XXX this is almost identical to sshkey_load_private_type() */ 160 int 161 sshkey_load_private(const char *filename, const char *passphrase, 162 struct sshkey **keyp, char **commentp) 163 { 164 struct sshbuf *buffer = NULL; 165 int r, fd; 166 167 if (keyp != NULL) 168 *keyp = NULL; 169 if (commentp != NULL) 170 *commentp = NULL; 171 172 if ((fd = open(filename, O_RDONLY)) == -1) 173 return SSH_ERR_SYSTEM_ERROR; 174 if (sshkey_perm_ok(fd, filename) != 0) { 175 r = SSH_ERR_KEY_BAD_PERMISSIONS; 176 goto out; 177 } 178 if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || 179 (r = sshkey_parse_private_fileblob(buffer, passphrase, keyp, 180 commentp)) != 0) 181 goto out; 182 if (keyp && *keyp && 183 (r = sshkey_set_filename(*keyp, filename)) != 0) 184 goto out; 185 r = 0; 186 out: 187 close(fd); 188 sshbuf_free(buffer); 189 return r; 190 } 191 192 static int 193 sshkey_try_load_public(struct sshkey *k, const char *filename, char **commentp) 194 { 195 FILE *f; 196 char *line = NULL, *cp; 197 size_t linesize = 0; 198 int r; 199 200 if (commentp != NULL) 201 *commentp = NULL; 202 if ((f = fopen(filename, "r")) == NULL) 203 return SSH_ERR_SYSTEM_ERROR; 204 while (getline(&line, &linesize, f) != -1) { 205 cp = line; 206 switch (*cp) { 207 case '#': 208 case '\n': 209 case '\0': 210 continue; 211 } 212 /* Abort loading if this looks like a private key */ 213 if (strncmp(cp, "-----BEGIN", 10) == 0 || 214 strcmp(cp, "SSH PRIVATE KEY FILE") == 0) 215 break; 216 /* Skip leading whitespace. */ 217 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 218 ; 219 if (*cp) { 220 if ((r = sshkey_read(k, &cp)) == 0) { 221 cp[strcspn(cp, "\r\n")] = '\0'; 222 if (commentp) { 223 *commentp = strdup(*cp ? 224 cp : filename); 225 if (*commentp == NULL) 226 r = SSH_ERR_ALLOC_FAIL; 227 } 228 free(line); 229 fclose(f); 230 return r; 231 } 232 } 233 } 234 free(line); 235 fclose(f); 236 return SSH_ERR_INVALID_FORMAT; 237 } 238 239 /* load public key from any pubkey file */ 240 int 241 sshkey_load_public(const char *filename, struct sshkey **keyp, char **commentp) 242 { 243 struct sshkey *pub = NULL; 244 char *file = NULL; 245 int r; 246 247 if (keyp != NULL) 248 *keyp = NULL; 249 if (commentp != NULL) 250 *commentp = NULL; 251 252 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) 253 return SSH_ERR_ALLOC_FAIL; 254 if ((r = sshkey_try_load_public(pub, filename, commentp)) == 0) { 255 if (keyp != NULL) { 256 *keyp = pub; 257 pub = NULL; 258 } 259 r = 0; 260 goto out; 261 } 262 sshkey_free(pub); 263 264 /* try .pub suffix */ 265 if (asprintf(&file, "%s.pub", filename) == -1) 266 return SSH_ERR_ALLOC_FAIL; 267 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 268 r = SSH_ERR_ALLOC_FAIL; 269 goto out; 270 } 271 if ((r = sshkey_try_load_public(pub, file, commentp)) == 0) { 272 if (keyp != NULL) { 273 *keyp = pub; 274 pub = NULL; 275 } 276 r = 0; 277 } 278 out: 279 free(file); 280 sshkey_free(pub); 281 return r; 282 } 283 284 /* Load the certificate associated with the named private key */ 285 int 286 sshkey_load_cert(const char *filename, struct sshkey **keyp) 287 { 288 struct sshkey *pub = NULL; 289 char *file = NULL; 290 int r = SSH_ERR_INTERNAL_ERROR; 291 292 if (keyp != NULL) 293 *keyp = NULL; 294 295 if (asprintf(&file, "%s-cert.pub", filename) == -1) 296 return SSH_ERR_ALLOC_FAIL; 297 298 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 299 goto out; 300 } 301 if ((r = sshkey_try_load_public(pub, file, NULL)) != 0) 302 goto out; 303 /* success */ 304 if (keyp != NULL) { 305 *keyp = pub; 306 pub = NULL; 307 } 308 r = 0; 309 out: 310 free(file); 311 sshkey_free(pub); 312 return r; 313 } 314 315 /* Load private key and certificate */ 316 int 317 sshkey_load_private_cert(int type, const char *filename, const char *passphrase, 318 struct sshkey **keyp) 319 { 320 struct sshkey *key = NULL, *cert = NULL; 321 int r; 322 323 if (keyp != NULL) 324 *keyp = NULL; 325 326 switch (type) { 327 #ifdef WITH_OPENSSL 328 case KEY_RSA: 329 case KEY_DSA: 330 case KEY_ECDSA: 331 #endif /* WITH_OPENSSL */ 332 case KEY_ED25519: 333 case KEY_XMSS: 334 case KEY_UNSPEC: 335 break; 336 default: 337 return SSH_ERR_KEY_TYPE_UNKNOWN; 338 } 339 340 if ((r = sshkey_load_private_type(type, filename, 341 passphrase, &key, NULL)) != 0 || 342 (r = sshkey_load_cert(filename, &cert)) != 0) 343 goto out; 344 345 /* Make sure the private key matches the certificate */ 346 if (sshkey_equal_public(key, cert) == 0) { 347 r = SSH_ERR_KEY_CERT_MISMATCH; 348 goto out; 349 } 350 351 if ((r = sshkey_to_certified(key)) != 0 || 352 (r = sshkey_cert_copy(cert, key)) != 0) 353 goto out; 354 r = 0; 355 if (keyp != NULL) { 356 *keyp = key; 357 key = NULL; 358 } 359 out: 360 sshkey_free(key); 361 sshkey_free(cert); 362 return r; 363 } 364 365 /* 366 * Returns success if the specified "key" is listed in the file "filename", 367 * SSH_ERR_KEY_NOT_FOUND: if the key is not listed or another error. 368 * If "strict_type" is set then the key type must match exactly, 369 * otherwise a comparison that ignores certficiate data is performed. 370 * If "check_ca" is set and "key" is a certificate, then its CA key is 371 * also checked and sshkey_in_file() will return success if either is found. 372 */ 373 int 374 sshkey_in_file(struct sshkey *key, const char *filename, int strict_type, 375 int check_ca) 376 { 377 FILE *f; 378 char *line = NULL, *cp; 379 size_t linesize = 0; 380 int r = 0; 381 struct sshkey *pub = NULL; 382 383 int (*sshkey_compare)(const struct sshkey *, const struct sshkey *) = 384 strict_type ? sshkey_equal : sshkey_equal_public; 385 386 if ((f = fopen(filename, "r")) == NULL) 387 return SSH_ERR_SYSTEM_ERROR; 388 389 while (getline(&line, &linesize, f) != -1) { 390 sshkey_free(pub); 391 pub = NULL; 392 cp = line; 393 394 /* Skip leading whitespace. */ 395 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 396 ; 397 398 /* Skip comments and empty lines */ 399 switch (*cp) { 400 case '#': 401 case '\n': 402 case '\0': 403 continue; 404 } 405 406 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 407 r = SSH_ERR_ALLOC_FAIL; 408 goto out; 409 } 410 switch (r = sshkey_read(pub, &cp)) { 411 case 0: 412 break; 413 case SSH_ERR_KEY_LENGTH: 414 continue; 415 default: 416 goto out; 417 } 418 if (sshkey_compare(key, pub) || 419 (check_ca && sshkey_is_cert(key) && 420 sshkey_compare(key->cert->signature_key, pub))) { 421 r = 0; 422 goto out; 423 } 424 } 425 r = SSH_ERR_KEY_NOT_FOUND; 426 out: 427 free(line); 428 sshkey_free(pub); 429 fclose(f); 430 return r; 431 } 432 433 /* 434 * Checks whether the specified key is revoked, returning 0 if not, 435 * SSH_ERR_KEY_REVOKED if it is or another error code if something 436 * unexpected happened. 437 * This will check both the key and, if it is a certificate, its CA key too. 438 * "revoked_keys_file" may be a KRL or a one-per-line list of public keys. 439 */ 440 int 441 sshkey_check_revoked(struct sshkey *key, const char *revoked_keys_file) 442 { 443 int r; 444 445 r = ssh_krl_file_contains_key(revoked_keys_file, key); 446 /* If this was not a KRL to begin with then continue below */ 447 if (r != SSH_ERR_KRL_BAD_MAGIC) 448 return r; 449 450 /* 451 * If the file is not a KRL or we can't handle KRLs then attempt to 452 * parse the file as a flat list of keys. 453 */ 454 switch ((r = sshkey_in_file(key, revoked_keys_file, 0, 1))) { 455 case 0: 456 /* Key found => revoked */ 457 return SSH_ERR_KEY_REVOKED; 458 case SSH_ERR_KEY_NOT_FOUND: 459 /* Key not found => not revoked */ 460 return 0; 461 default: 462 /* Some other error occurred */ 463 return r; 464 } 465 } 466 467 /* 468 * Advanced *cpp past the end of key options, defined as the first unquoted 469 * whitespace character. Returns 0 on success or -1 on failure (e.g. 470 * unterminated quotes). 471 */ 472 int 473 sshkey_advance_past_options(char **cpp) 474 { 475 char *cp = *cpp; 476 int quoted = 0; 477 478 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { 479 if (*cp == '\\' && cp[1] == '"') 480 cp++; /* Skip both */ 481 else if (*cp == '"') 482 quoted = !quoted; 483 } 484 *cpp = cp; 485 /* return failure for unterminated quotes */ 486 return (*cp == '\0' && quoted) ? -1 : 0; 487 } 488 489 /* Save a public key */ 490 int 491 sshkey_save_public(const struct sshkey *key, const char *path, 492 const char *comment) 493 { 494 int fd, oerrno; 495 FILE *f = NULL; 496 int r = SSH_ERR_INTERNAL_ERROR; 497 498 if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1) 499 return SSH_ERR_SYSTEM_ERROR; 500 if ((f = fdopen(fd, "w")) == NULL) { 501 r = SSH_ERR_SYSTEM_ERROR; 502 goto fail; 503 } 504 if ((r = sshkey_write(key, f)) != 0) 505 goto fail; 506 fprintf(f, " %s\n", comment); 507 if (ferror(f) || fclose(f) != 0) { 508 r = SSH_ERR_SYSTEM_ERROR; 509 fail: 510 oerrno = errno; 511 if (f != NULL) 512 fclose(f); 513 else 514 close(fd); 515 errno = oerrno; 516 return r; 517 } 518 return 0; 519 } 520