Annotation of src/usr.bin/ssh/authfile.c, Revision 1.19
1.1 deraadt 1: /*
1.9 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * This file contains functions for reading and writing identity files, and
6: * for reading the passphrase from the user.
1.14 markus 7: *
1.19 ! deraadt 8: * As far as I am concerned, the code I have written for this software
! 9: * can be used freely for any purpose. Any derived versions of this
! 10: * software must be clearly marked as such, and if the derived work is
! 11: * incompatible with the protocol description in the RFC file, it must be
! 12: * called by a name other than "ssh" or "Secure Shell".
! 13: *
! 14: *
! 15: * Copyright (c) 2000 Markus Friedl. All rights reserved.
! 16: *
! 17: * Redistribution and use in source and binary forms, with or without
! 18: * modification, are permitted provided that the following conditions
! 19: * are met:
! 20: * 1. Redistributions of source code must retain the above copyright
! 21: * notice, this list of conditions and the following disclaimer.
! 22: * 2. Redistributions in binary form must reproduce the above copyright
! 23: * notice, this list of conditions and the following disclaimer in the
! 24: * documentation and/or other materials provided with the distribution.
! 25: *
! 26: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
! 27: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
! 28: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
! 29: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
! 30: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
! 31: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
! 32: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
! 33: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
! 34: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
! 35: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.9 deraadt 36: */
1.1 deraadt 37:
38: #include "includes.h"
1.19 ! deraadt 39: RCSID("$OpenBSD: authfile.c,v 1.18 2000/09/05 19:18:47 markus Exp $");
1.1 deraadt 40:
1.13 markus 41: #include <openssl/bn.h>
1.15 markus 42: #include <openssl/dsa.h>
43: #include <openssl/rsa.h>
44: #include <openssl/pem.h>
45: #include <openssl/evp.h>
46:
1.1 deraadt 47: #include "xmalloc.h"
48: #include "buffer.h"
49: #include "bufaux.h"
50: #include "cipher.h"
51: #include "ssh.h"
1.15 markus 52: #include "key.h"
1.1 deraadt 53:
54: /* Version identification string for identity files. */
55: #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
56:
1.10 markus 57: /*
58: * Saves the authentication (private) key in a file, encrypting it with
59: * passphrase. The identification of the file (lowest 64 bits of n) will
60: * precede the key to provide identification of the key without needing a
61: * passphrase.
62: */
1.1 deraadt 63:
1.3 provos 64: int
1.15 markus 65: save_private_key_rsa(const char *filename, const char *passphrase,
66: RSA *key, const char *comment)
1.1 deraadt 67: {
1.8 markus 68: Buffer buffer, encrypted;
69: char buf[100], *cp;
1.11 deraadt 70: int fd, i;
1.8 markus 71: CipherContext cipher;
72: int cipher_type;
73: u_int32_t rand;
74:
1.10 markus 75: /*
76: * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
77: * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
78: */
1.8 markus 79: if (strcmp(passphrase, "") == 0)
80: cipher_type = SSH_CIPHER_NONE;
81: else
82: cipher_type = SSH_AUTHFILE_CIPHER;
83:
84: /* This buffer is used to built the secret part of the private key. */
85: buffer_init(&buffer);
86:
87: /* Put checkbytes for checking passphrase validity. */
88: rand = arc4random();
89: buf[0] = rand & 0xff;
90: buf[1] = (rand >> 8) & 0xff;
91: buf[2] = buf[0];
92: buf[3] = buf[1];
93: buffer_append(&buffer, buf, 4);
94:
1.10 markus 95: /*
96: * Store the private key (n and e will not be stored because they
97: * will be stored in plain text, and storing them also in encrypted
98: * format would just give known plaintext).
99: */
1.8 markus 100: buffer_put_bignum(&buffer, key->d);
101: buffer_put_bignum(&buffer, key->iqmp);
102: buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
103: buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */
104:
105: /* Pad the part to be encrypted until its size is a multiple of 8. */
106: while (buffer_len(&buffer) % 8 != 0)
107: buffer_put_char(&buffer, 0);
108:
109: /* This buffer will be used to contain the data in the file. */
110: buffer_init(&encrypted);
111:
112: /* First store keyfile id string. */
113: cp = AUTHFILE_ID_STRING;
114: for (i = 0; cp[i]; i++)
115: buffer_put_char(&encrypted, cp[i]);
116: buffer_put_char(&encrypted, 0);
117:
118: /* Store cipher type. */
119: buffer_put_char(&encrypted, cipher_type);
120: buffer_put_int(&encrypted, 0); /* For future extension */
121:
122: /* Store public key. This will be in plain text. */
123: buffer_put_int(&encrypted, BN_num_bits(key->n));
124: buffer_put_bignum(&encrypted, key->n);
125: buffer_put_bignum(&encrypted, key->e);
126: buffer_put_string(&encrypted, comment, strlen(comment));
127:
128: /* Allocate space for the private part of the key in the buffer. */
129: buffer_append_space(&encrypted, &cp, buffer_len(&buffer));
130:
1.12 markus 131: cipher_set_key_string(&cipher, cipher_type, passphrase);
1.8 markus 132: cipher_encrypt(&cipher, (unsigned char *) cp,
133: (unsigned char *) buffer_ptr(&buffer),
134: buffer_len(&buffer));
135: memset(&cipher, 0, sizeof(cipher));
136:
137: /* Destroy temporary data. */
138: memset(buf, 0, sizeof(buf));
139: buffer_free(&buffer);
140:
1.11 deraadt 141: fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
142: if (fd < 0)
1.8 markus 143: return 0;
1.11 deraadt 144: if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
1.8 markus 145: buffer_len(&encrypted)) {
146: debug("Write to key file %.200s failed: %.100s", filename,
147: strerror(errno));
148: buffer_free(&encrypted);
1.11 deraadt 149: close(fd);
1.8 markus 150: remove(filename);
151: return 0;
152: }
1.11 deraadt 153: close(fd);
1.8 markus 154: buffer_free(&encrypted);
155: return 1;
1.1 deraadt 156: }
157:
1.15 markus 158: /* save DSA key in OpenSSL PEM format */
159:
160: int
161: save_private_key_dsa(const char *filename, const char *passphrase,
162: DSA *dsa, const char *comment)
163: {
164: FILE *fp;
165: int fd;
166: int success = 1;
167: int len = strlen(passphrase);
168:
169: if (len > 0 && len <= 4) {
170: error("passphrase too short: %d bytes", len);
171: errno = 0;
172: return 0;
173: }
174: fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
175: if (fd < 0) {
176: debug("open %s failed", filename);
177: return 0;
178: }
179: fp = fdopen(fd, "w");
180: if (fp == NULL ) {
181: debug("fdopen %s failed", filename);
182: close(fd);
183: return 0;
184: }
185: if (len > 0) {
186: if (!PEM_write_DSAPrivateKey(fp, dsa, EVP_des_ede3_cbc(),
187: (char *)passphrase, strlen(passphrase), NULL, NULL))
188: success = 0;
189: } else {
190: if (!PEM_write_DSAPrivateKey(fp, dsa, NULL,
191: NULL, 0, NULL, NULL))
192: success = 0;
193: }
194: fclose(fp);
195: return success;
196: }
197:
198: int
199: save_private_key(const char *filename, const char *passphrase, Key *key,
200: const char *comment)
201: {
202: switch (key->type) {
203: case KEY_RSA:
204: return save_private_key_rsa(filename, passphrase, key->rsa, comment);
205: break;
206: case KEY_DSA:
207: return save_private_key_dsa(filename, passphrase, key->dsa, comment);
208: break;
209: default:
210: break;
211: }
212: return 0;
213: }
214:
1.10 markus 215: /*
216: * Loads the public part of the key file. Returns 0 if an error was
217: * encountered (the file does not exist or is not readable), and non-zero
218: * otherwise.
219: */
1.1 deraadt 220:
1.3 provos 221: int
1.15 markus 222: load_public_key_rsa(const char *filename, RSA * pub, char **comment_return)
1.1 deraadt 223: {
1.11 deraadt 224: int fd, i;
1.8 markus 225: off_t len;
226: Buffer buffer;
227: char *cp;
228:
1.11 deraadt 229: fd = open(filename, O_RDONLY);
230: if (fd < 0)
1.8 markus 231: return 0;
1.11 deraadt 232: len = lseek(fd, (off_t) 0, SEEK_END);
233: lseek(fd, (off_t) 0, SEEK_SET);
1.8 markus 234:
235: buffer_init(&buffer);
236: buffer_append_space(&buffer, &cp, len);
237:
1.11 deraadt 238: if (read(fd, cp, (size_t) len) != (size_t) len) {
1.8 markus 239: debug("Read from key file %.200s failed: %.100s", filename,
1.15 markus 240: strerror(errno));
1.8 markus 241: buffer_free(&buffer);
1.11 deraadt 242: close(fd);
1.8 markus 243: return 0;
244: }
1.11 deraadt 245: close(fd);
1.8 markus 246:
247: /* Check that it is at least big enought to contain the ID string. */
248: if (len < strlen(AUTHFILE_ID_STRING) + 1) {
249: debug("Bad key file %.200s.", filename);
250: buffer_free(&buffer);
251: return 0;
252: }
1.10 markus 253: /*
254: * Make sure it begins with the id string. Consume the id string
255: * from the buffer.
256: */
1.8 markus 257: for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
1.11 deraadt 258: if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
1.8 markus 259: debug("Bad key file %.200s.", filename);
260: buffer_free(&buffer);
261: return 0;
262: }
263: /* Skip cipher type and reserved data. */
264: (void) buffer_get_char(&buffer); /* cipher type */
265: (void) buffer_get_int(&buffer); /* reserved */
266:
267: /* Read the public key from the buffer. */
268: buffer_get_int(&buffer);
1.15 markus 269: /* XXX alloc */
270: if (pub->n == NULL)
271: pub->n = BN_new();
1.8 markus 272: buffer_get_bignum(&buffer, pub->n);
1.15 markus 273: /* XXX alloc */
274: if (pub->e == NULL)
275: pub->e = BN_new();
1.8 markus 276: buffer_get_bignum(&buffer, pub->e);
277: if (comment_return)
278: *comment_return = buffer_get_string(&buffer, NULL);
279: /* The encrypted private part is not parsed by this function. */
280:
1.1 deraadt 281: buffer_free(&buffer);
282:
1.8 markus 283: return 1;
1.1 deraadt 284: }
285:
1.18 markus 286: /* load public key from private-key file */
1.15 markus 287: int
288: load_public_key(const char *filename, Key * key, char **comment_return)
289: {
290: switch (key->type) {
291: case KEY_RSA:
292: return load_public_key_rsa(filename, key->rsa, comment_return);
293: break;
294: case KEY_DSA:
295: default:
296: break;
297: }
298: return 0;
299: }
300:
1.10 markus 301: /*
302: * Loads the private key from the file. Returns 0 if an error is encountered
303: * (file does not exist or is not readable, or passphrase is bad). This
304: * initializes the private key.
305: * Assumes we are called under uid of the owner of the file.
306: */
1.1 deraadt 307:
1.3 provos 308: int
1.15 markus 309: load_private_key_rsa(int fd, const char *filename,
310: const char *passphrase, RSA * prv, char **comment_return)
1.1 deraadt 311: {
1.15 markus 312: int i, check1, check2, cipher_type;
1.8 markus 313: off_t len;
314: Buffer buffer, decrypted;
315: char *cp;
316: CipherContext cipher;
317: BN_CTX *ctx;
318: BIGNUM *aux;
319:
1.11 deraadt 320: len = lseek(fd, (off_t) 0, SEEK_END);
321: lseek(fd, (off_t) 0, SEEK_SET);
1.8 markus 322:
323: buffer_init(&buffer);
324: buffer_append_space(&buffer, &cp, len);
325:
1.11 deraadt 326: if (read(fd, cp, (size_t) len) != (size_t) len) {
1.8 markus 327: debug("Read from key file %.200s failed: %.100s", filename,
328: strerror(errno));
329: buffer_free(&buffer);
1.11 deraadt 330: close(fd);
1.8 markus 331: return 0;
332: }
1.11 deraadt 333: close(fd);
1.8 markus 334:
335: /* Check that it is at least big enought to contain the ID string. */
336: if (len < strlen(AUTHFILE_ID_STRING) + 1) {
337: debug("Bad key file %.200s.", filename);
338: buffer_free(&buffer);
339: return 0;
340: }
1.10 markus 341: /*
342: * Make sure it begins with the id string. Consume the id string
343: * from the buffer.
344: */
1.8 markus 345: for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
346: if (buffer_get_char(&buffer) != (unsigned char) AUTHFILE_ID_STRING[i]) {
347: debug("Bad key file %.200s.", filename);
348: buffer_free(&buffer);
349: return 0;
350: }
351: /* Read cipher type. */
352: cipher_type = buffer_get_char(&buffer);
353: (void) buffer_get_int(&buffer); /* Reserved data. */
354:
355: /* Read the public key from the buffer. */
356: buffer_get_int(&buffer);
357: prv->n = BN_new();
358: buffer_get_bignum(&buffer, prv->n);
359: prv->e = BN_new();
360: buffer_get_bignum(&buffer, prv->e);
361: if (comment_return)
362: *comment_return = buffer_get_string(&buffer, NULL);
363: else
364: xfree(buffer_get_string(&buffer, NULL));
365:
366: /* Check that it is a supported cipher. */
1.12 markus 367: if (((cipher_mask1() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) &
1.8 markus 368: (1 << cipher_type)) == 0) {
369: debug("Unsupported cipher %.100s used in key file %.200s.",
370: cipher_name(cipher_type), filename);
371: buffer_free(&buffer);
372: goto fail;
373: }
374: /* Initialize space for decrypted data. */
375: buffer_init(&decrypted);
376: buffer_append_space(&decrypted, &cp, buffer_len(&buffer));
377:
378: /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
1.12 markus 379: cipher_set_key_string(&cipher, cipher_type, passphrase);
1.8 markus 380: cipher_decrypt(&cipher, (unsigned char *) cp,
381: (unsigned char *) buffer_ptr(&buffer),
382: buffer_len(&buffer));
383:
1.1 deraadt 384: buffer_free(&buffer);
385:
1.8 markus 386: check1 = buffer_get_char(&decrypted);
387: check2 = buffer_get_char(&decrypted);
388: if (check1 != buffer_get_char(&decrypted) ||
389: check2 != buffer_get_char(&decrypted)) {
390: if (strcmp(passphrase, "") != 0)
391: debug("Bad passphrase supplied for key file %.200s.", filename);
392: /* Bad passphrase. */
393: buffer_free(&decrypted);
394: fail:
395: BN_clear_free(prv->n);
1.15 markus 396: prv->n = NULL;
1.8 markus 397: BN_clear_free(prv->e);
1.15 markus 398: prv->e = NULL;
1.8 markus 399: if (comment_return)
400: xfree(*comment_return);
401: return 0;
402: }
403: /* Read the rest of the private key. */
404: prv->d = BN_new();
405: buffer_get_bignum(&decrypted, prv->d);
406: prv->iqmp = BN_new();
407: buffer_get_bignum(&decrypted, prv->iqmp); /* u */
408: /* in SSL and SSH p and q are exchanged */
409: prv->q = BN_new();
410: buffer_get_bignum(&decrypted, prv->q); /* p */
411: prv->p = BN_new();
412: buffer_get_bignum(&decrypted, prv->p); /* q */
413:
414: ctx = BN_CTX_new();
415: aux = BN_new();
416:
417: BN_sub(aux, prv->q, BN_value_one());
418: prv->dmq1 = BN_new();
419: BN_mod(prv->dmq1, prv->d, aux, ctx);
420:
421: BN_sub(aux, prv->p, BN_value_one());
422: prv->dmp1 = BN_new();
423: BN_mod(prv->dmp1, prv->d, aux, ctx);
424:
425: BN_clear_free(aux);
426: BN_CTX_free(ctx);
427:
428: buffer_free(&decrypted);
1.1 deraadt 429:
1.8 markus 430: return 1;
1.15 markus 431: }
432:
433: int
434: load_private_key_dsa(int fd, const char *passphrase, Key *k, char **comment_return)
435: {
436: DSA *dsa;
437: BIO *in;
438: FILE *fp;
439:
440: in = BIO_new(BIO_s_file());
441: if (in == NULL) {
442: error("BIO_new failed");
443: return 0;
444: }
445: fp = fdopen(fd, "r");
446: if (fp == NULL) {
447: error("fdopen failed");
448: return 0;
449: }
450: BIO_set_fp(in, fp, BIO_NOCLOSE);
451: dsa = PEM_read_bio_DSAPrivateKey(in, NULL, NULL, (char *)passphrase);
452: if (dsa == NULL) {
453: debug("PEM_read_bio_DSAPrivateKey failed");
454: } else {
455: /* replace k->dsa with loaded key */
456: DSA_free(k->dsa);
457: k->dsa = dsa;
458: }
459: BIO_free(in);
460: fclose(fp);
461: if (comment_return)
462: *comment_return = xstrdup("dsa w/o comment");
463: debug("read DSA private key done");
464: #ifdef DEBUG_DSS
465: DSA_print_fp(stderr, dsa, 8);
466: #endif
467: return dsa != NULL ? 1 : 0;
468: }
469:
470: int
471: load_private_key(const char *filename, const char *passphrase, Key *key,
472: char **comment_return)
473: {
474: int fd;
475: int ret = 0;
476: struct stat st;
477:
478: fd = open(filename, O_RDONLY);
479: if (fd < 0)
480: return 0;
481:
482: /* check owner and modes */
483: if (fstat(fd, &st) < 0 ||
484: (st.st_uid != 0 && st.st_uid != getuid()) ||
485: (st.st_mode & 077) != 0) {
486: close(fd);
487: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
488: error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
489: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
490: error("Bad ownership or mode(0%3.3o) for '%s'.",
491: st.st_mode & 0777, filename);
492: error("It is recommended that your private key files are NOT accessible by others.");
493: return 0;
494: }
495: switch (key->type) {
496: case KEY_RSA:
497: if (key->rsa->e != NULL) {
498: BN_clear_free(key->rsa->e);
499: key->rsa->e = NULL;
500: }
501: if (key->rsa->n != NULL) {
502: BN_clear_free(key->rsa->n);
503: key->rsa->n = NULL;
504: }
505: ret = load_private_key_rsa(fd, filename, passphrase,
506: key->rsa, comment_return);
507: break;
508: case KEY_DSA:
509: ret = load_private_key_dsa(fd, passphrase, key, comment_return);
510: default:
511: break;
512: }
513: close(fd);
514: return ret;
1.18 markus 515: }
516:
517: int
518: do_load_public_key(const char *filename, Key *k, char **commentp)
519: {
520: FILE *f;
521: unsigned int bits;
522: char line[1024];
523: char *cp;
524:
525: f = fopen(filename, "r");
526: if (f != NULL) {
527: while (fgets(line, sizeof(line), f)) {
528: line[sizeof(line)-1] = '\0';
529: cp = line;
530: switch(*cp){
531: case '#':
532: case '\n':
533: case '\0':
534: continue;
535: }
536: /* Skip leading whitespace. */
537: for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
538: ;
539: if (*cp) {
540: bits = key_read(k, &cp);
541: if (bits != 0) {
542: if (commentp)
543: *commentp=xstrdup(filename);
544: fclose(f);
545: return 1;
546: }
547: }
548: }
549: fclose(f);
550: }
551: return 0;
552: }
553:
554: /* load public key from pubkey file */
555: int
556: try_load_public_key(const char *filename, Key *k, char **commentp)
557: {
558: char pub[MAXPATHLEN];
559:
560: if (do_load_public_key(filename, k, commentp) == 1)
561: return 1;
562: if (strlcpy(pub, filename, sizeof pub) >= MAXPATHLEN)
563: return 0;
564: if (strlcat(pub, ".pub", sizeof pub) >= MAXPATHLEN)
565: return 0;
566: if (do_load_public_key(pub, k, commentp) == 1)
567: return 1;
568: return 0;
1.1 deraadt 569: }
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