1 /* $OpenBSD: authfile.c,v 1.71 2006/07/22 20:48:22 stevesk Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This file contains functions for reading and writing identity files, and
7 * for reading the passphrase from the user.
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".
16 * Copyright (c) 2000 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
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.
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.
41 #include <sys/types.h>
44 #include <openssl/err.h>
45 #include <openssl/evp.h>
46 #include <openssl/pem.h>
65 /* Version identification string for SSH v1 identity files. */
66 static const char authfile_id_string[] =
67 "SSH PRIVATE KEY FILE FORMAT 1.1\n";
70 * Saves the authentication (private) key in a file, encrypting it with
71 * passphrase. The identification of the file (lowest 64 bits of n) will
72 * precede the key to provide identification of the key without needing a
77 key_save_private_rsa1(Key *key, const char *filename, const char *passphrase,
80 Buffer buffer, encrypted;
82 int fd, i, cipher_num;
83 CipherContext ciphercontext;
88 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
89 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
91 cipher_num = (strcmp(passphrase, "") == 0) ?
92 SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER;
93 if ((cipher = cipher_by_number(cipher_num)) == NULL)
94 fatal("save_private_key_rsa: bad cipher");
96 /* This buffer is used to built the secret part of the private key. */
99 /* Put checkbytes for checking passphrase validity. */
102 buf[1] = (rnd >> 8) & 0xff;
105 buffer_append(&buffer, buf, 4);
108 * Store the private key (n and e will not be stored because they
109 * will be stored in plain text, and storing them also in encrypted
110 * format would just give known plaintext).
112 buffer_put_bignum(&buffer, key->rsa->d);
113 buffer_put_bignum(&buffer, key->rsa->iqmp);
114 buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */
115 buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */
117 /* Pad the part to be encrypted until its size is a multiple of 8. */
118 while (buffer_len(&buffer) % 8 != 0)
119 buffer_put_char(&buffer, 0);
121 /* This buffer will be used to contain the data in the file. */
122 buffer_init(&encrypted);
124 /* First store keyfile id string. */
125 for (i = 0; authfile_id_string[i]; i++)
126 buffer_put_char(&encrypted, authfile_id_string[i]);
127 buffer_put_char(&encrypted, 0);
129 /* Store cipher type. */
130 buffer_put_char(&encrypted, cipher_num);
131 buffer_put_int(&encrypted, 0); /* For future extension */
133 /* Store public key. This will be in plain text. */
134 buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
135 buffer_put_bignum(&encrypted, key->rsa->n);
136 buffer_put_bignum(&encrypted, key->rsa->e);
137 buffer_put_cstring(&encrypted, comment);
139 /* Allocate space for the private part of the key in the buffer. */
140 cp = buffer_append_space(&encrypted, buffer_len(&buffer));
142 cipher_set_key_string(&ciphercontext, cipher, passphrase,
144 cipher_crypt(&ciphercontext, cp,
145 buffer_ptr(&buffer), buffer_len(&buffer));
146 cipher_cleanup(&ciphercontext);
147 memset(&ciphercontext, 0, sizeof(ciphercontext));
149 /* Destroy temporary data. */
150 memset(buf, 0, sizeof(buf));
151 buffer_free(&buffer);
153 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
155 error("open %s failed: %s.", filename, strerror(errno));
156 buffer_free(&encrypted);
159 if (atomicio(vwrite, fd, buffer_ptr(&encrypted),
160 buffer_len(&encrypted)) != buffer_len(&encrypted)) {
161 error("write to key file %s failed: %s", filename,
163 buffer_free(&encrypted);
169 buffer_free(&encrypted);
173 /* save SSH v2 key in OpenSSL PEM format */
175 key_save_private_pem(Key *key, const char *filename, const char *_passphrase,
181 int len = strlen(_passphrase);
182 u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
183 const EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;
185 if (len > 0 && len <= 4) {
186 error("passphrase too short: have %d bytes, need > 4", len);
189 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
191 error("open %s failed: %s.", filename, strerror(errno));
194 fp = fdopen(fd, "w");
196 error("fdopen %s failed: %s.", filename, strerror(errno));
202 success = PEM_write_DSAPrivateKey(fp, key->dsa,
203 cipher, passphrase, len, NULL, NULL);
206 success = PEM_write_RSAPrivateKey(fp, key->rsa,
207 cipher, passphrase, len, NULL, NULL);
215 key_save_private(Key *key, const char *filename, const char *passphrase,
220 return key_save_private_rsa1(key, filename, passphrase,
224 return key_save_private_pem(key, filename, passphrase,
229 error("key_save_private: cannot save key type %d", key->type);
234 * Loads the public part of the ssh v1 key file. Returns NULL if an error was
235 * encountered (the file does not exist or is not readable), and the key
240 key_load_public_rsa1(int fd, const char *filename, char **commentp)
249 if (fstat(fd, &st) < 0) {
250 error("fstat for key file %.200s failed: %.100s",
251 filename, strerror(errno));
254 if (st.st_size > 1*1024*1024) {
255 error("key file %.200s too large", filename);
258 len = (size_t)st.st_size; /* truncated */
260 buffer_init(&buffer);
261 cp = buffer_append_space(&buffer, len);
263 if (atomicio(read, fd, cp, len) != len) {
264 debug("Read from key file %.200s failed: %.100s", filename,
266 buffer_free(&buffer);
270 /* Check that it is at least big enough to contain the ID string. */
271 if (len < sizeof(authfile_id_string)) {
272 debug3("Not a RSA1 key file %.200s.", filename);
273 buffer_free(&buffer);
277 * Make sure it begins with the id string. Consume the id string
280 for (i = 0; i < sizeof(authfile_id_string); i++)
281 if (buffer_get_char(&buffer) != authfile_id_string[i]) {
282 debug3("Not a RSA1 key file %.200s.", filename);
283 buffer_free(&buffer);
286 /* Skip cipher type and reserved data. */
287 (void) buffer_get_char(&buffer); /* cipher type */
288 (void) buffer_get_int(&buffer); /* reserved */
290 /* Read the public key from the buffer. */
291 (void) buffer_get_int(&buffer);
292 pub = key_new(KEY_RSA1);
293 buffer_get_bignum(&buffer, pub->rsa->n);
294 buffer_get_bignum(&buffer, pub->rsa->e);
296 *commentp = buffer_get_string(&buffer, NULL);
297 /* The encrypted private part is not parsed by this function. */
299 buffer_free(&buffer);
303 /* load public key from private-key file, works only for SSH v1 */
305 key_load_public_type(int type, const char *filename, char **commentp)
310 if (type == KEY_RSA1) {
311 fd = open(filename, O_RDONLY);
314 pub = key_load_public_rsa1(fd, filename, commentp);
322 * Loads the private key from the file. Returns 0 if an error is encountered
323 * (file does not exist or is not readable, or passphrase is bad). This
324 * initializes the private key.
325 * Assumes we are called under uid of the owner of the file.
329 key_load_private_rsa1(int fd, const char *filename, const char *passphrase,
333 int check1, check2, cipher_type;
335 Buffer buffer, decrypted;
337 CipherContext ciphercontext;
342 if (fstat(fd, &st) < 0) {
343 error("fstat for key file %.200s failed: %.100s",
344 filename, strerror(errno));
348 if (st.st_size > 1*1024*1024) {
349 error("key file %.200s too large", filename);
353 len = (size_t)st.st_size; /* truncated */
355 buffer_init(&buffer);
356 cp = buffer_append_space(&buffer, len);
358 if (atomicio(read, fd, cp, len) != len) {
359 debug("Read from key file %.200s failed: %.100s", filename,
361 buffer_free(&buffer);
366 /* Check that it is at least big enough to contain the ID string. */
367 if (len < sizeof(authfile_id_string)) {
368 debug3("Not a RSA1 key file %.200s.", filename);
369 buffer_free(&buffer);
374 * Make sure it begins with the id string. Consume the id string
377 for (i = 0; i < sizeof(authfile_id_string); i++)
378 if (buffer_get_char(&buffer) != authfile_id_string[i]) {
379 debug3("Not a RSA1 key file %.200s.", filename);
380 buffer_free(&buffer);
385 /* Read cipher type. */
386 cipher_type = buffer_get_char(&buffer);
387 (void) buffer_get_int(&buffer); /* Reserved data. */
389 /* Read the public key from the buffer. */
390 (void) buffer_get_int(&buffer);
391 prv = key_new_private(KEY_RSA1);
393 buffer_get_bignum(&buffer, prv->rsa->n);
394 buffer_get_bignum(&buffer, prv->rsa->e);
396 *commentp = buffer_get_string(&buffer, NULL);
398 xfree(buffer_get_string(&buffer, NULL));
400 /* Check that it is a supported cipher. */
401 cipher = cipher_by_number(cipher_type);
402 if (cipher == NULL) {
403 debug("Unsupported cipher %d used in key file %.200s.",
404 cipher_type, filename);
405 buffer_free(&buffer);
408 /* Initialize space for decrypted data. */
409 buffer_init(&decrypted);
410 cp = buffer_append_space(&decrypted, buffer_len(&buffer));
412 /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
413 cipher_set_key_string(&ciphercontext, cipher, passphrase,
415 cipher_crypt(&ciphercontext, cp,
416 buffer_ptr(&buffer), buffer_len(&buffer));
417 cipher_cleanup(&ciphercontext);
418 memset(&ciphercontext, 0, sizeof(ciphercontext));
419 buffer_free(&buffer);
421 check1 = buffer_get_char(&decrypted);
422 check2 = buffer_get_char(&decrypted);
423 if (check1 != buffer_get_char(&decrypted) ||
424 check2 != buffer_get_char(&decrypted)) {
425 if (strcmp(passphrase, "") != 0)
426 debug("Bad passphrase supplied for key file %.200s.",
428 /* Bad passphrase. */
429 buffer_free(&decrypted);
432 /* Read the rest of the private key. */
433 buffer_get_bignum(&decrypted, prv->rsa->d);
434 buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */
435 /* in SSL and SSH v1 p and q are exchanged */
436 buffer_get_bignum(&decrypted, prv->rsa->q); /* p */
437 buffer_get_bignum(&decrypted, prv->rsa->p); /* q */
439 /* calculate p-1 and q-1 */
440 rsa_generate_additional_parameters(prv->rsa);
442 buffer_free(&decrypted);
444 /* enable blinding */
445 if (RSA_blinding_on(prv->rsa, NULL) != 1) {
446 error("key_load_private_rsa1: RSA_blinding_on failed");
461 key_load_private_pem(int fd, int type, const char *passphrase,
467 char *name = "<no key>";
469 fp = fdopen(fd, "r");
471 error("fdopen failed: %s", strerror(errno));
475 pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
477 debug("PEM_read_PrivateKey failed");
478 (void)ERR_get_error();
479 } else if (pk->type == EVP_PKEY_RSA &&
480 (type == KEY_UNSPEC||type==KEY_RSA)) {
481 prv = key_new(KEY_UNSPEC);
482 prv->rsa = EVP_PKEY_get1_RSA(pk);
484 name = "rsa w/o comment";
486 RSA_print_fp(stderr, prv->rsa, 8);
488 if (RSA_blinding_on(prv->rsa, NULL) != 1) {
489 error("key_load_private_pem: RSA_blinding_on failed");
493 } else if (pk->type == EVP_PKEY_DSA &&
494 (type == KEY_UNSPEC||type==KEY_DSA)) {
495 prv = key_new(KEY_UNSPEC);
496 prv->dsa = EVP_PKEY_get1_DSA(pk);
498 name = "dsa w/o comment";
500 DSA_print_fp(stderr, prv->dsa, 8);
503 error("PEM_read_PrivateKey: mismatch or "
504 "unknown EVP_PKEY save_type %d", pk->save_type);
509 if (prv != NULL && commentp)
510 *commentp = xstrdup(name);
511 debug("read PEM private key done: type %s",
512 prv ? key_type(prv) : "<unknown>");
517 key_perm_ok(int fd, const char *filename)
521 if (fstat(fd, &st) < 0)
524 * if a key owned by the user is accessed, then we check the
525 * permissions of the file. if the key owned by a different user,
526 * then we don't care.
529 if (check_ntsec(filename))
531 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
532 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
533 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
534 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
535 error("Permissions 0%3.3o for '%s' are too open.",
536 (u_int)st.st_mode & 0777, filename);
537 error("It is recommended that your private key files are NOT accessible by others.");
538 error("This private key will be ignored.");
545 key_load_private_type(int type, const char *filename, const char *passphrase,
546 char **commentp, int *perm_ok)
550 fd = open(filename, O_RDONLY);
553 if (!key_perm_ok(fd, filename)) {
556 error("bad permissions: ignore key: %s", filename);
564 return key_load_private_rsa1(fd, filename, passphrase,
570 return key_load_private_pem(fd, type, passphrase, commentp);
580 key_load_private(const char *filename, const char *passphrase,
586 fd = open(filename, O_RDONLY);
589 if (!key_perm_ok(fd, filename)) {
590 error("bad permissions: ignore key: %s", filename);
594 pub = key_load_public_rsa1(fd, filename, commentp);
595 lseek(fd, (off_t) 0, SEEK_SET); /* rewind */
598 prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
599 /* use the filename as a comment for PEM */
601 *commentp = xstrdup(filename);
603 /* it's a SSH v1 key if the public key part is readable */
606 prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
612 key_try_load_public(Key *k, const char *filename, char **commentp)
615 char line[SSH_MAX_PUBKEY_BYTES];
619 f = fopen(filename, "r");
621 while (read_keyfile_line(f, filename, line, sizeof(line),
630 /* Skip leading whitespace. */
631 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
634 if (key_read(k, &cp) == 1) {
636 *commentp=xstrdup(filename);
647 /* load public key from ssh v1 private or any pubkey file */
649 key_load_public(const char *filename, char **commentp)
652 char file[MAXPATHLEN];
654 /* try rsa1 private key */
655 pub = key_load_public_type(KEY_RSA1, filename, commentp);
659 /* try rsa1 public key */
660 pub = key_new(KEY_RSA1);
661 if (key_try_load_public(pub, filename, commentp) == 1)
665 /* try ssh2 public key */
666 pub = key_new(KEY_UNSPEC);
667 if (key_try_load_public(pub, filename, commentp) == 1)
669 if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
670 (strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
671 (key_try_load_public(pub, file, commentp) == 1))