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9108f8d9 | 1 | /* $OpenBSD: cipher.c,v 1.81 2006/08/03 03:34:42 deraadt Exp $ */ |
3c0ef626 | 2 | /* |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * | |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
12 | * | |
13 | * | |
14 | * Copyright (c) 1999 Niels Provos. All rights reserved. | |
15 | * Copyright (c) 1999, 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. | |
36 | */ | |
37 | ||
38 | #include "includes.h" | |
9108f8d9 | 39 | |
40 | #include <sys/types.h> | |
41 | ||
42 | #include <openssl/md5.h> | |
43 | ||
44 | #include <string.h> | |
45 | #include <stdarg.h> | |
3c0ef626 | 46 | |
47 | #include "xmalloc.h" | |
48 | #include "log.h" | |
49 | #include "cipher.h" | |
50 | ||
665a873d | 51 | /* compatibility with old or broken OpenSSL versions */ |
52 | #include "openbsd-compat/openssl-compat.h" | |
cdd66111 | 53 | |
0fff78ff | 54 | extern const EVP_CIPHER *evp_ssh1_bf(void); |
55 | extern const EVP_CIPHER *evp_ssh1_3des(void); | |
56 | extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); | |
57 | extern const EVP_CIPHER *evp_aes_128_ctr(void); | |
58 | extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
e9a17296 | 59 | |
60 | struct Cipher { | |
61 | char *name; | |
62 | int number; /* for ssh1 only */ | |
63 | u_int block_size; | |
64 | u_int key_len; | |
665a873d | 65 | u_int discard_len; |
f5799ae1 | 66 | const EVP_CIPHER *(*evptype)(void); |
e9a17296 | 67 | } ciphers[] = { |
665a873d | 68 | { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null }, |
69 | { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc }, | |
70 | { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des }, | |
71 | { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf }, | |
72 | ||
73 | { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc }, | |
74 | { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc }, | |
75 | { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc }, | |
76 | { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 }, | |
77 | { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 }, | |
78 | { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 }, | |
79 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc }, | |
80 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc }, | |
81 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, | |
700318f3 | 82 | { "rijndael-cbc@lysator.liu.se", |
665a873d | 83 | SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, |
84 | { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr }, | |
85 | { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_128_ctr }, | |
86 | { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_128_ctr }, | |
87 | #ifdef USE_CIPHER_ACSS | |
88 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, EVP_acss }, | |
acc3d05e | 89 | #endif |
665a873d | 90 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, NULL } |
e9a17296 | 91 | }; |
3c0ef626 | 92 | |
e9a17296 | 93 | /*--*/ |
3c0ef626 | 94 | |
700318f3 | 95 | u_int |
cdd66111 | 96 | cipher_blocksize(const Cipher *c) |
3c0ef626 | 97 | { |
e9a17296 | 98 | return (c->block_size); |
3c0ef626 | 99 | } |
680cee3b | 100 | |
700318f3 | 101 | u_int |
cdd66111 | 102 | cipher_keylen(const Cipher *c) |
3c0ef626 | 103 | { |
e9a17296 | 104 | return (c->key_len); |
3c0ef626 | 105 | } |
680cee3b | 106 | |
700318f3 | 107 | u_int |
cdd66111 | 108 | cipher_get_number(const Cipher *c) |
700318f3 | 109 | { |
110 | return (c->number); | |
111 | } | |
3c0ef626 | 112 | |
3c0ef626 | 113 | u_int |
114 | cipher_mask_ssh1(int client) | |
115 | { | |
116 | u_int mask = 0; | |
e9a17296 | 117 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
3c0ef626 | 118 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
119 | if (client) { | |
120 | mask |= 1 << SSH_CIPHER_DES; | |
121 | } | |
122 | return mask; | |
123 | } | |
124 | ||
125 | Cipher * | |
126 | cipher_by_name(const char *name) | |
127 | { | |
128 | Cipher *c; | |
129 | for (c = ciphers; c->name != NULL; c++) | |
996d5e62 | 130 | if (strcmp(c->name, name) == 0) |
3c0ef626 | 131 | return c; |
132 | return NULL; | |
133 | } | |
134 | ||
135 | Cipher * | |
136 | cipher_by_number(int id) | |
137 | { | |
138 | Cipher *c; | |
139 | for (c = ciphers; c->name != NULL; c++) | |
140 | if (c->number == id) | |
141 | return c; | |
142 | return NULL; | |
143 | } | |
144 | ||
145 | #define CIPHER_SEP "," | |
146 | int | |
147 | ciphers_valid(const char *names) | |
148 | { | |
149 | Cipher *c; | |
c9f39d2c | 150 | char *cipher_list, *cp; |
3c0ef626 | 151 | char *p; |
152 | ||
153 | if (names == NULL || strcmp(names, "") == 0) | |
154 | return 0; | |
c9f39d2c | 155 | cipher_list = cp = xstrdup(names); |
3c0ef626 | 156 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
e9a17296 | 157 | (p = strsep(&cp, CIPHER_SEP))) { |
3c0ef626 | 158 | c = cipher_by_name(p); |
159 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { | |
160 | debug("bad cipher %s [%s]", p, names); | |
c9f39d2c | 161 | xfree(cipher_list); |
3c0ef626 | 162 | return 0; |
163 | } else { | |
164 | debug3("cipher ok: %s [%s]", p, names); | |
165 | } | |
166 | } | |
167 | debug3("ciphers ok: [%s]", names); | |
c9f39d2c | 168 | xfree(cipher_list); |
3c0ef626 | 169 | return 1; |
170 | } | |
171 | ||
172 | /* | |
173 | * Parses the name of the cipher. Returns the number of the corresponding | |
174 | * cipher, or -1 on error. | |
175 | */ | |
176 | ||
177 | int | |
178 | cipher_number(const char *name) | |
179 | { | |
180 | Cipher *c; | |
181 | if (name == NULL) | |
182 | return -1; | |
996d5e62 | 183 | for (c = ciphers; c->name != NULL; c++) |
184 | if (strcasecmp(c->name, name) == 0) | |
185 | return c->number; | |
186 | return -1; | |
3c0ef626 | 187 | } |
188 | ||
189 | char * | |
190 | cipher_name(int id) | |
191 | { | |
192 | Cipher *c = cipher_by_number(id); | |
193 | return (c==NULL) ? "<unknown>" : c->name; | |
194 | } | |
195 | ||
196 | void | |
197 | cipher_init(CipherContext *cc, Cipher *cipher, | |
e9a17296 | 198 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
c9f39d2c | 199 | int do_encrypt) |
3c0ef626 | 200 | { |
e9a17296 | 201 | static int dowarn = 1; |
700318f3 | 202 | #ifdef SSH_OLD_EVP |
203 | EVP_CIPHER *type; | |
204 | #else | |
e9a17296 | 205 | const EVP_CIPHER *type; |
206 | int klen; | |
665a873d | 207 | #endif |
208 | u_char *junk, *discard; | |
e9a17296 | 209 | |
210 | if (cipher->number == SSH_CIPHER_DES) { | |
211 | if (dowarn) { | |
212 | error("Warning: use of DES is strongly discouraged " | |
213 | "due to cryptographic weaknesses"); | |
214 | dowarn = 0; | |
215 | } | |
216 | if (keylen > 8) | |
217 | keylen = 8; | |
218 | } | |
219 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); | |
220 | ||
3c0ef626 | 221 | if (keylen < cipher->key_len) |
222 | fatal("cipher_init: key length %d is insufficient for %s.", | |
223 | keylen, cipher->name); | |
224 | if (iv != NULL && ivlen < cipher->block_size) | |
225 | fatal("cipher_init: iv length %d is insufficient for %s.", | |
226 | ivlen, cipher->name); | |
227 | cc->cipher = cipher; | |
e9a17296 | 228 | |
229 | type = (*cipher->evptype)(); | |
230 | ||
231 | EVP_CIPHER_CTX_init(&cc->evp); | |
700318f3 | 232 | #ifdef SSH_OLD_EVP |
233 | if (type->key_len > 0 && type->key_len != keylen) { | |
234 | debug("cipher_init: set keylen (%d -> %d)", | |
235 | type->key_len, keylen); | |
236 | type->key_len = keylen; | |
237 | } | |
238 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, | |
c9f39d2c | 239 | (do_encrypt == CIPHER_ENCRYPT)); |
700318f3 | 240 | #else |
e9a17296 | 241 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
c9f39d2c | 242 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
e9a17296 | 243 | fatal("cipher_init: EVP_CipherInit failed for %s", |
244 | cipher->name); | |
245 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); | |
665a873d | 246 | if (klen > 0 && keylen != (u_int)klen) { |
6a9b3198 | 247 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
e9a17296 | 248 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
249 | fatal("cipher_init: set keylen failed (%d -> %d)", | |
250 | klen, keylen); | |
251 | } | |
252 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) | |
253 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", | |
254 | cipher->name); | |
700318f3 | 255 | #endif |
665a873d | 256 | |
257 | if (cipher->discard_len > 0) { | |
258 | junk = xmalloc(cipher->discard_len); | |
259 | discard = xmalloc(cipher->discard_len); | |
260 | if (EVP_Cipher(&cc->evp, discard, junk, | |
261 | cipher->discard_len) == 0) | |
262 | fatal("evp_crypt: EVP_Cipher failed during discard"); | |
263 | memset(discard, 0, cipher->discard_len); | |
264 | xfree(junk); | |
265 | xfree(discard); | |
266 | } | |
3c0ef626 | 267 | } |
268 | ||
269 | void | |
e9a17296 | 270 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
3c0ef626 | 271 | { |
272 | if (len % cc->cipher->block_size) | |
273 | fatal("cipher_encrypt: bad plaintext length %d", len); | |
e9a17296 | 274 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
275 | fatal("evp_crypt: EVP_Cipher failed"); | |
3c0ef626 | 276 | } |
277 | ||
278 | void | |
e9a17296 | 279 | cipher_cleanup(CipherContext *cc) |
3c0ef626 | 280 | { |
e9a17296 | 281 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
282 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); | |
3c0ef626 | 283 | } |
284 | ||
285 | /* | |
286 | * Selects the cipher, and keys if by computing the MD5 checksum of the | |
287 | * passphrase and using the resulting 16 bytes as the key. | |
288 | */ | |
289 | ||
290 | void | |
291 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, | |
c9f39d2c | 292 | const char *passphrase, int do_encrypt) |
3c0ef626 | 293 | { |
294 | MD5_CTX md; | |
295 | u_char digest[16]; | |
296 | ||
297 | MD5_Init(&md); | |
298 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); | |
299 | MD5_Final(digest, &md); | |
300 | ||
c9f39d2c | 301 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
3c0ef626 | 302 | |
303 | memset(digest, 0, sizeof(digest)); | |
304 | memset(&md, 0, sizeof(md)); | |
305 | } | |
e9a17296 | 306 | |
700318f3 | 307 | /* |
308 | * Exports an IV from the CipherContext required to export the key | |
309 | * state back from the unprivileged child to the privileged parent | |
310 | * process. | |
311 | */ | |
312 | ||
313 | int | |
cdd66111 | 314 | cipher_get_keyiv_len(const CipherContext *cc) |
700318f3 | 315 | { |
316 | Cipher *c = cc->cipher; | |
317 | int ivlen; | |
318 | ||
319 | if (c->number == SSH_CIPHER_3DES) | |
320 | ivlen = 24; | |
321 | else | |
322 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
323 | return (ivlen); | |
324 | } | |
325 | ||
326 | void | |
327 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) | |
328 | { | |
329 | Cipher *c = cc->cipher; | |
700318f3 | 330 | int evplen; |
331 | ||
332 | switch (c->number) { | |
333 | case SSH_CIPHER_SSH2: | |
334 | case SSH_CIPHER_DES: | |
335 | case SSH_CIPHER_BLOWFISH: | |
336 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
665a873d | 337 | if (evplen <= 0) |
700318f3 | 338 | return; |
665a873d | 339 | if ((u_int)evplen != len) |
f5799ae1 | 340 | fatal("%s: wrong iv length %d != %d", __func__, |
700318f3 | 341 | evplen, len); |
2c06c99b | 342 | #ifdef USE_BUILTIN_RIJNDAEL |
0fff78ff | 343 | if (c->evptype == evp_rijndael) |
344 | ssh_rijndael_iv(&cc->evp, 0, iv, len); | |
345 | else | |
f5799ae1 | 346 | #endif |
0fff78ff | 347 | if (c->evptype == evp_aes_128_ctr) |
348 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); | |
349 | else | |
350 | memcpy(iv, cc->evp.iv, len); | |
351 | break; | |
352 | case SSH_CIPHER_3DES: | |
353 | ssh1_3des_iv(&cc->evp, 0, iv, 24); | |
700318f3 | 354 | break; |
700318f3 | 355 | default: |
f5799ae1 | 356 | fatal("%s: bad cipher %d", __func__, c->number); |
700318f3 | 357 | } |
700318f3 | 358 | } |
359 | ||
360 | void | |
361 | cipher_set_keyiv(CipherContext *cc, u_char *iv) | |
362 | { | |
363 | Cipher *c = cc->cipher; | |
700318f3 | 364 | int evplen = 0; |
365 | ||
366 | switch (c->number) { | |
367 | case SSH_CIPHER_SSH2: | |
368 | case SSH_CIPHER_DES: | |
369 | case SSH_CIPHER_BLOWFISH: | |
370 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); | |
371 | if (evplen == 0) | |
372 | return; | |
2c06c99b | 373 | #ifdef USE_BUILTIN_RIJNDAEL |
0fff78ff | 374 | if (c->evptype == evp_rijndael) |
375 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); | |
376 | else | |
f5799ae1 | 377 | #endif |
0fff78ff | 378 | if (c->evptype == evp_aes_128_ctr) |
379 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); | |
380 | else | |
381 | memcpy(cc->evp.iv, iv, evplen); | |
382 | break; | |
383 | case SSH_CIPHER_3DES: | |
384 | ssh1_3des_iv(&cc->evp, 1, iv, 24); | |
700318f3 | 385 | break; |
700318f3 | 386 | default: |
f5799ae1 | 387 | fatal("%s: bad cipher %d", __func__, c->number); |
700318f3 | 388 | } |
700318f3 | 389 | } |
390 | ||
391 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
392 | #define EVP_X_STATE(evp) &(evp).c | |
393 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) | |
394 | #else | |
395 | #define EVP_X_STATE(evp) (evp).cipher_data | |
396 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size | |
397 | #endif | |
398 | ||
399 | int | |
cdd66111 | 400 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
700318f3 | 401 | { |
402 | Cipher *c = cc->cipher; | |
f5799ae1 | 403 | int plen = 0; |
700318f3 | 404 | |
cdd66111 | 405 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
f5799ae1 | 406 | plen = EVP_X_STATE_LEN(cc->evp); |
700318f3 | 407 | if (dat == NULL) |
f5799ae1 | 408 | return (plen); |
409 | memcpy(dat, EVP_X_STATE(cc->evp), plen); | |
700318f3 | 410 | } |
700318f3 | 411 | return (plen); |
412 | } | |
413 | ||
414 | void | |
415 | cipher_set_keycontext(CipherContext *cc, u_char *dat) | |
416 | { | |
417 | Cipher *c = cc->cipher; | |
418 | int plen; | |
419 | ||
cdd66111 | 420 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
700318f3 | 421 | plen = EVP_X_STATE_LEN(cc->evp); |
422 | memcpy(EVP_X_STATE(cc->evp), dat, plen); | |
423 | } | |
424 | } |