1 /* $NetBSD: authfile.c,v 1.24 2020/05/28 17:05:49 christos Exp $ */ 2 /* $OpenBSD: authfile.c,v 1.140 2020/04/17 07:15:11 djm Exp $ */ 3 /* 4 * Copyright (c) 2000, 2013 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$NetBSD: authfile.c,v 1.24 2020/05/28 17:05:49 christos Exp $"); 29 #include <sys/types.h> 30 #include <sys/stat.h> 31 #include <sys/uio.h> 32 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <stdio.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 r; 59 mode_t omask; 60 61 omask = umask(077); 62 r = sshbuf_write_file(filename, keybuf); 63 umask(omask); 64 return r; 65 } 66 67 int 68 sshkey_save_private(struct sshkey *key, const char *filename, 69 const char *passphrase, const char *comment, 70 int format, const char *openssh_format_cipher, int openssh_format_rounds) 71 { 72 struct sshbuf *keyblob = NULL; 73 int r; 74 75 if ((keyblob = sshbuf_new()) == NULL) 76 return SSH_ERR_ALLOC_FAIL; 77 if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment, 78 format, openssh_format_cipher, openssh_format_rounds)) != 0) 79 goto out; 80 if ((r = sshkey_save_private_blob(keyblob, filename)) != 0) 81 goto out; 82 r = 0; 83 out: 84 sshbuf_free(keyblob); 85 return r; 86 } 87 88 /* XXX remove error() calls from here? */ 89 int 90 sshkey_perm_ok(int fd, const char *filename) 91 { 92 struct stat st; 93 94 if (fstat(fd, &st) == -1) 95 return SSH_ERR_SYSTEM_ERROR; 96 /* 97 * if a key owned by the user is accessed, then we check the 98 * permissions of the file. if the key owned by a different user, 99 * then we don't care. 100 */ 101 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) { 102 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 103 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @"); 104 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 105 error("Permissions 0%3.3o for '%s' are too open.", 106 (u_int)st.st_mode & 0777, filename); 107 error("It is required that your private key files are NOT accessible by others."); 108 error("This private key will be ignored."); 109 return SSH_ERR_KEY_BAD_PERMISSIONS; 110 } 111 return 0; 112 } 113 114 int 115 sshkey_load_private_type(int type, const char *filename, const char *passphrase, 116 struct sshkey **keyp, char **commentp) 117 { 118 int fd, r; 119 120 if (keyp != NULL) 121 *keyp = NULL; 122 if (commentp != NULL) 123 *commentp = NULL; 124 125 if ((fd = open(filename, O_RDONLY)) == -1) 126 return SSH_ERR_SYSTEM_ERROR; 127 128 r = sshkey_perm_ok(fd, filename); 129 if (r != 0) 130 goto out; 131 132 r = sshkey_load_private_type_fd(fd, type, passphrase, keyp, commentp); 133 if (r == 0 && keyp && *keyp) 134 r = sshkey_set_filename(*keyp, filename); 135 out: 136 close(fd); 137 return r; 138 } 139 140 int 141 sshkey_load_private(const char *filename, const char *passphrase, 142 struct sshkey **keyp, char **commentp) 143 { 144 return sshkey_load_private_type(KEY_UNSPEC, filename, passphrase, 145 keyp, commentp); 146 } 147 148 int 149 sshkey_load_private_type_fd(int fd, int type, const char *passphrase, 150 struct sshkey **keyp, char **commentp) 151 { 152 struct sshbuf *buffer = NULL; 153 int r; 154 155 if (keyp != NULL) 156 *keyp = NULL; 157 if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || 158 (r = sshkey_parse_private_fileblob_type(buffer, type, 159 passphrase, keyp, commentp)) != 0) 160 goto out; 161 162 /* success */ 163 r = 0; 164 out: 165 sshbuf_free(buffer); 166 return r; 167 } 168 169 /* Load a pubkey from the unencrypted envelope of a new-format private key */ 170 static int 171 sshkey_load_pubkey_from_private(const char *filename, struct sshkey **pubkeyp) 172 { 173 struct sshbuf *buffer = NULL; 174 struct sshkey *pubkey = NULL; 175 int r, fd; 176 177 if (pubkeyp != NULL) 178 *pubkeyp = NULL; 179 180 if ((fd = open(filename, O_RDONLY)) == -1) 181 return SSH_ERR_SYSTEM_ERROR; 182 if ((r = sshbuf_load_fd(fd, &buffer)) != 0 || 183 (r = sshkey_parse_pubkey_from_private_fileblob_type(buffer, 184 KEY_UNSPEC, &pubkey)) != 0) 185 goto out; 186 if ((r = sshkey_set_filename(pubkey, filename)) != 0) 187 goto out; 188 /* success */ 189 if (pubkeyp != NULL) { 190 *pubkeyp = pubkey; 191 pubkey = NULL; 192 } 193 r = 0; 194 out: 195 close(fd); 196 sshbuf_free(buffer); 197 sshkey_free(pubkey); 198 return r; 199 } 200 201 static int 202 sshkey_try_load_public(struct sshkey **kp, const char *filename, 203 char **commentp) 204 { 205 FILE *f; 206 char *line = NULL, *cp; 207 size_t linesize = 0; 208 int r; 209 struct sshkey *k = NULL; 210 211 *kp = NULL; 212 if (commentp != NULL) 213 *commentp = NULL; 214 if ((f = fopen(filename, "r")) == NULL) 215 return SSH_ERR_SYSTEM_ERROR; 216 if ((k = sshkey_new(KEY_UNSPEC)) == NULL) { 217 fclose(f); 218 return SSH_ERR_ALLOC_FAIL; 219 } 220 while (getline(&line, &linesize, f) != -1) { 221 cp = line; 222 switch (*cp) { 223 case '#': 224 case '\n': 225 case '\0': 226 continue; 227 } 228 /* Abort loading if this looks like a private key */ 229 if (strncmp(cp, "-----BEGIN", 10) == 0 || 230 strcmp(cp, "SSH PRIVATE KEY FILE") == 0) 231 break; 232 /* Skip leading whitespace. */ 233 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 234 ; 235 if (*cp) { 236 if ((r = sshkey_read(k, &cp)) == 0) { 237 cp[strcspn(cp, "\r\n")] = '\0'; 238 if (commentp) { 239 *commentp = strdup(*cp ? 240 cp : filename); 241 if (*commentp == NULL) 242 r = SSH_ERR_ALLOC_FAIL; 243 } 244 /* success */ 245 *kp = k; 246 free(line); 247 fclose(f); 248 return r; 249 } 250 } 251 } 252 free(k); 253 free(line); 254 fclose(f); 255 return SSH_ERR_INVALID_FORMAT; 256 } 257 258 /* load public key from any pubkey file */ 259 int 260 sshkey_load_public(const char *filename, struct sshkey **keyp, char **commentp) 261 { 262 char *pubfile = NULL; 263 int r; 264 265 if (keyp != NULL) 266 *keyp = NULL; 267 if (commentp != NULL) 268 *commentp = NULL; 269 270 if ((r = sshkey_try_load_public(keyp, filename, commentp)) == 0) 271 goto out; 272 273 /* try .pub suffix */ 274 if (asprintf(&pubfile, "%s.pub", filename) == -1) 275 return SSH_ERR_ALLOC_FAIL; 276 if ((r = sshkey_try_load_public(keyp, pubfile, commentp)) == 0) 277 goto out; 278 279 /* finally, try to extract public key from private key file */ 280 if ((r = sshkey_load_pubkey_from_private(filename, keyp)) == 0) 281 goto out; 282 283 out: 284 free(pubfile); 285 return r; 286 } 287 288 /* Load the certificate associated with the named private key */ 289 int 290 sshkey_load_cert(const char *filename, struct sshkey **keyp) 291 { 292 struct sshkey *pub = NULL; 293 char *file = NULL; 294 int r = SSH_ERR_INTERNAL_ERROR; 295 296 if (keyp != NULL) 297 *keyp = NULL; 298 299 if (asprintf(&file, "%s-cert.pub", filename) == -1) 300 return SSH_ERR_ALLOC_FAIL; 301 302 r = sshkey_try_load_public(keyp, file, NULL); 303 free(file); 304 sshkey_free(pub); 305 return r; 306 } 307 308 /* Load private key and certificate */ 309 int 310 sshkey_load_private_cert(int type, const char *filename, const char *passphrase, 311 struct sshkey **keyp) 312 { 313 struct sshkey *key = NULL, *cert = NULL; 314 int r; 315 316 if (keyp != NULL) 317 *keyp = NULL; 318 319 switch (type) { 320 #ifdef WITH_OPENSSL 321 case KEY_RSA: 322 case KEY_DSA: 323 case KEY_ECDSA: 324 #endif /* WITH_OPENSSL */ 325 case KEY_ED25519: 326 case KEY_XMSS: 327 case KEY_UNSPEC: 328 break; 329 default: 330 return SSH_ERR_KEY_TYPE_UNKNOWN; 331 } 332 333 if ((r = sshkey_load_private_type(type, filename, 334 passphrase, &key, NULL)) != 0 || 335 (r = sshkey_load_cert(filename, &cert)) != 0) 336 goto out; 337 338 /* Make sure the private key matches the certificate */ 339 if (sshkey_equal_public(key, cert) == 0) { 340 r = SSH_ERR_KEY_CERT_MISMATCH; 341 goto out; 342 } 343 344 if ((r = sshkey_to_certified(key)) != 0 || 345 (r = sshkey_cert_copy(cert, key)) != 0) 346 goto out; 347 r = 0; 348 if (keyp != NULL) { 349 *keyp = key; 350 key = NULL; 351 } 352 out: 353 sshkey_free(key); 354 sshkey_free(cert); 355 return r; 356 } 357 358 /* 359 * Returns success if the specified "key" is listed in the file "filename", 360 * SSH_ERR_KEY_NOT_FOUND: if the key is not listed or another error. 361 * If "strict_type" is set then the key type must match exactly, 362 * otherwise a comparison that ignores certficiate data is performed. 363 * If "check_ca" is set and "key" is a certificate, then its CA key is 364 * also checked and sshkey_in_file() will return success if either is found. 365 */ 366 int 367 sshkey_in_file(struct sshkey *key, const char *filename, int strict_type, 368 int check_ca) 369 { 370 FILE *f; 371 char *line = NULL, *cp; 372 size_t linesize = 0; 373 int r = 0; 374 struct sshkey *pub = NULL; 375 376 int (*sshkey_compare)(const struct sshkey *, const struct sshkey *) = 377 strict_type ? sshkey_equal : sshkey_equal_public; 378 379 if ((f = fopen(filename, "r")) == NULL) 380 return SSH_ERR_SYSTEM_ERROR; 381 382 while (getline(&line, &linesize, f) != -1) { 383 sshkey_free(pub); 384 pub = NULL; 385 cp = line; 386 387 /* Skip leading whitespace. */ 388 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++) 389 ; 390 391 /* Skip comments and empty lines */ 392 switch (*cp) { 393 case '#': 394 case '\n': 395 case '\0': 396 continue; 397 } 398 399 if ((pub = sshkey_new(KEY_UNSPEC)) == NULL) { 400 r = SSH_ERR_ALLOC_FAIL; 401 goto out; 402 } 403 switch (r = sshkey_read(pub, &cp)) { 404 case 0: 405 break; 406 case SSH_ERR_KEY_LENGTH: 407 continue; 408 default: 409 goto out; 410 } 411 if (sshkey_compare(key, pub) || 412 (check_ca && sshkey_is_cert(key) && 413 sshkey_compare(key->cert->signature_key, pub))) { 414 r = 0; 415 goto out; 416 } 417 } 418 r = SSH_ERR_KEY_NOT_FOUND; 419 out: 420 free(line); 421 sshkey_free(pub); 422 fclose(f); 423 return r; 424 } 425 426 /* 427 * Checks whether the specified key is revoked, returning 0 if not, 428 * SSH_ERR_KEY_REVOKED if it is or another error code if something 429 * unexpected happened. 430 * This will check both the key and, if it is a certificate, its CA key too. 431 * "revoked_keys_file" may be a KRL or a one-per-line list of public keys. 432 */ 433 int 434 sshkey_check_revoked(struct sshkey *key, const char *revoked_keys_file) 435 { 436 int r; 437 438 r = ssh_krl_file_contains_key(revoked_keys_file, key); 439 /* If this was not a KRL to begin with then continue below */ 440 if (r != SSH_ERR_KRL_BAD_MAGIC) 441 return r; 442 443 /* 444 * If the file is not a KRL or we can't handle KRLs then attempt to 445 * parse the file as a flat list of keys. 446 */ 447 switch ((r = sshkey_in_file(key, revoked_keys_file, 0, 1))) { 448 case 0: 449 /* Key found => revoked */ 450 return SSH_ERR_KEY_REVOKED; 451 case SSH_ERR_KEY_NOT_FOUND: 452 /* Key not found => not revoked */ 453 return 0; 454 default: 455 /* Some other error occurred */ 456 return r; 457 } 458 } 459 460 /* 461 * Advanced *cpp past the end of key options, defined as the first unquoted 462 * whitespace character. Returns 0 on success or -1 on failure (e.g. 463 * unterminated quotes). 464 */ 465 int 466 sshkey_advance_past_options(char **cpp) 467 { 468 char *cp = *cpp; 469 int quoted = 0; 470 471 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { 472 if (*cp == '\\' && cp[1] == '"') 473 cp++; /* Skip both */ 474 else if (*cp == '"') 475 quoted = !quoted; 476 } 477 *cpp = cp; 478 /* return failure for unterminated quotes */ 479 return (*cp == '\0' && quoted) ? -1 : 0; 480 } 481 482 /* Save a public key */ 483 int 484 sshkey_save_public(const struct sshkey *key, const char *path, 485 const char *comment) 486 { 487 int fd, oerrno; 488 FILE *f = NULL; 489 int r = SSH_ERR_INTERNAL_ERROR; 490 491 if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0644)) == -1) 492 return SSH_ERR_SYSTEM_ERROR; 493 if ((f = fdopen(fd, "w")) == NULL) { 494 r = SSH_ERR_SYSTEM_ERROR; 495 goto fail; 496 } 497 if ((r = sshkey_write(key, f)) != 0) 498 goto fail; 499 fprintf(f, " %s\n", comment); 500 if (ferror(f) || fclose(f) != 0) { 501 r = SSH_ERR_SYSTEM_ERROR; 502 fail: 503 oerrno = errno; 504 if (f != NULL) 505 fclose(f); 506 else 507 close(fd); 508 errno = oerrno; 509 return r; 510 } 511 return 0; 512 } 513