Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame^] | 1 | /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */ |
| 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" |
| 39 | |
| 40 | #include <sys/types.h> |
| 41 | |
| 42 | #include <openssl/md5.h> |
| 43 | |
| 44 | #include <string.h> |
| 45 | #include <stdarg.h> |
| 46 | |
| 47 | #include "xmalloc.h" |
| 48 | #include "log.h" |
| 49 | #include "cipher.h" |
| 50 | |
| 51 | /* compatibility with old or broken OpenSSL versions */ |
| 52 | #include "openbsd-compat/openssl-compat.h" |
| 53 | |
| 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); |
| 59 | |
| 60 | struct Cipher { |
| 61 | char *name; |
| 62 | int number; /* for ssh1 only */ |
| 63 | u_int block_size; |
| 64 | u_int key_len; |
| 65 | u_int discard_len; |
| 66 | u_int cbc_mode; |
| 67 | const EVP_CIPHER *(*evptype)(void); |
| 68 | } ciphers[] = { |
| 69 | { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null }, |
| 70 | { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc }, |
| 71 | { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des }, |
| 72 | { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf }, |
| 73 | |
| 74 | { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc }, |
| 75 | { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc }, |
| 76 | #ifndef ANDROID |
| 77 | { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc }, |
| 78 | #endif |
| 79 | { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 }, |
| 80 | { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 }, |
| 81 | { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 }, |
| 82 | { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc }, |
| 83 | { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc }, |
| 84 | { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, |
| 85 | { "rijndael-cbc@lysator.liu.se", |
| 86 | SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, |
| 87 | { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr }, |
| 88 | { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr }, |
| 89 | { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr }, |
| 90 | #ifdef USE_CIPHER_ACSS |
| 91 | { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss }, |
| 92 | #endif |
| 93 | { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL } |
| 94 | }; |
| 95 | |
| 96 | /*--*/ |
| 97 | |
| 98 | u_int |
| 99 | cipher_blocksize(const Cipher *c) |
| 100 | { |
| 101 | return (c->block_size); |
| 102 | } |
| 103 | |
| 104 | u_int |
| 105 | cipher_keylen(const Cipher *c) |
| 106 | { |
| 107 | return (c->key_len); |
| 108 | } |
| 109 | |
| 110 | u_int |
| 111 | cipher_get_number(const Cipher *c) |
| 112 | { |
| 113 | return (c->number); |
| 114 | } |
| 115 | |
| 116 | u_int |
| 117 | cipher_is_cbc(const Cipher *c) |
| 118 | { |
| 119 | return (c->cbc_mode); |
| 120 | } |
| 121 | |
| 122 | u_int |
| 123 | cipher_mask_ssh1(int client) |
| 124 | { |
| 125 | u_int mask = 0; |
| 126 | mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ |
| 127 | mask |= 1 << SSH_CIPHER_BLOWFISH; |
| 128 | if (client) { |
| 129 | mask |= 1 << SSH_CIPHER_DES; |
| 130 | } |
| 131 | return mask; |
| 132 | } |
| 133 | |
| 134 | Cipher * |
| 135 | cipher_by_name(const char *name) |
| 136 | { |
| 137 | Cipher *c; |
| 138 | for (c = ciphers; c->name != NULL; c++) |
| 139 | if (strcmp(c->name, name) == 0) |
| 140 | return c; |
| 141 | return NULL; |
| 142 | } |
| 143 | |
| 144 | Cipher * |
| 145 | cipher_by_number(int id) |
| 146 | { |
| 147 | Cipher *c; |
| 148 | for (c = ciphers; c->name != NULL; c++) |
| 149 | if (c->number == id) |
| 150 | return c; |
| 151 | return NULL; |
| 152 | } |
| 153 | |
| 154 | #define CIPHER_SEP "," |
| 155 | int |
| 156 | ciphers_valid(const char *names) |
| 157 | { |
| 158 | Cipher *c; |
| 159 | char *cipher_list, *cp; |
| 160 | char *p; |
| 161 | |
| 162 | if (names == NULL || strcmp(names, "") == 0) |
| 163 | return 0; |
| 164 | cipher_list = cp = xstrdup(names); |
| 165 | for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; |
| 166 | (p = strsep(&cp, CIPHER_SEP))) { |
| 167 | c = cipher_by_name(p); |
| 168 | if (c == NULL || c->number != SSH_CIPHER_SSH2) { |
| 169 | debug("bad cipher %s [%s]", p, names); |
| 170 | xfree(cipher_list); |
| 171 | return 0; |
| 172 | } else { |
| 173 | debug3("cipher ok: %s [%s]", p, names); |
| 174 | } |
| 175 | } |
| 176 | debug3("ciphers ok: [%s]", names); |
| 177 | xfree(cipher_list); |
| 178 | return 1; |
| 179 | } |
| 180 | |
| 181 | /* |
| 182 | * Parses the name of the cipher. Returns the number of the corresponding |
| 183 | * cipher, or -1 on error. |
| 184 | */ |
| 185 | |
| 186 | int |
| 187 | cipher_number(const char *name) |
| 188 | { |
| 189 | Cipher *c; |
| 190 | if (name == NULL) |
| 191 | return -1; |
| 192 | for (c = ciphers; c->name != NULL; c++) |
| 193 | if (strcasecmp(c->name, name) == 0) |
| 194 | return c->number; |
| 195 | return -1; |
| 196 | } |
| 197 | |
| 198 | char * |
| 199 | cipher_name(int id) |
| 200 | { |
| 201 | Cipher *c = cipher_by_number(id); |
| 202 | return (c==NULL) ? "<unknown>" : c->name; |
| 203 | } |
| 204 | |
| 205 | void |
| 206 | cipher_init(CipherContext *cc, Cipher *cipher, |
| 207 | const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, |
| 208 | int do_encrypt) |
| 209 | { |
| 210 | static int dowarn = 1; |
| 211 | #ifdef SSH_OLD_EVP |
| 212 | EVP_CIPHER *type; |
| 213 | #else |
| 214 | const EVP_CIPHER *type; |
| 215 | int klen; |
| 216 | #endif |
| 217 | u_char *junk, *discard; |
| 218 | |
| 219 | if (cipher->number == SSH_CIPHER_DES) { |
| 220 | if (dowarn) { |
| 221 | error("Warning: use of DES is strongly discouraged " |
| 222 | "due to cryptographic weaknesses"); |
| 223 | dowarn = 0; |
| 224 | } |
| 225 | if (keylen > 8) |
| 226 | keylen = 8; |
| 227 | } |
| 228 | cc->plaintext = (cipher->number == SSH_CIPHER_NONE); |
| 229 | |
| 230 | if (keylen < cipher->key_len) |
| 231 | fatal("cipher_init: key length %d is insufficient for %s.", |
| 232 | keylen, cipher->name); |
| 233 | if (iv != NULL && ivlen < cipher->block_size) |
| 234 | fatal("cipher_init: iv length %d is insufficient for %s.", |
| 235 | ivlen, cipher->name); |
| 236 | cc->cipher = cipher; |
| 237 | |
| 238 | type = (*cipher->evptype)(); |
| 239 | |
| 240 | EVP_CIPHER_CTX_init(&cc->evp); |
| 241 | #ifdef SSH_OLD_EVP |
| 242 | if (type->key_len > 0 && type->key_len != keylen) { |
| 243 | debug("cipher_init: set keylen (%d -> %d)", |
| 244 | type->key_len, keylen); |
| 245 | type->key_len = keylen; |
| 246 | } |
| 247 | EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, |
| 248 | (do_encrypt == CIPHER_ENCRYPT)); |
| 249 | #else |
| 250 | if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, |
| 251 | (do_encrypt == CIPHER_ENCRYPT)) == 0) |
| 252 | fatal("cipher_init: EVP_CipherInit failed for %s", |
| 253 | cipher->name); |
| 254 | klen = EVP_CIPHER_CTX_key_length(&cc->evp); |
| 255 | if (klen > 0 && keylen != (u_int)klen) { |
| 256 | debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); |
| 257 | if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) |
| 258 | fatal("cipher_init: set keylen failed (%d -> %d)", |
| 259 | klen, keylen); |
| 260 | } |
| 261 | if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) |
| 262 | fatal("cipher_init: EVP_CipherInit: set key failed for %s", |
| 263 | cipher->name); |
| 264 | #endif |
| 265 | |
| 266 | if (cipher->discard_len > 0) { |
| 267 | junk = xmalloc(cipher->discard_len); |
| 268 | discard = xmalloc(cipher->discard_len); |
| 269 | if (EVP_Cipher(&cc->evp, discard, junk, |
| 270 | cipher->discard_len) == 0) |
| 271 | fatal("evp_crypt: EVP_Cipher failed during discard"); |
| 272 | memset(discard, 0, cipher->discard_len); |
| 273 | xfree(junk); |
| 274 | xfree(discard); |
| 275 | } |
| 276 | } |
| 277 | |
| 278 | void |
| 279 | cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| 280 | { |
| 281 | if (len % cc->cipher->block_size) |
| 282 | fatal("cipher_encrypt: bad plaintext length %d", len); |
| 283 | if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) |
| 284 | fatal("evp_crypt: EVP_Cipher failed"); |
| 285 | } |
| 286 | |
| 287 | void |
| 288 | cipher_cleanup(CipherContext *cc) |
| 289 | { |
| 290 | if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) |
| 291 | error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); |
| 292 | } |
| 293 | |
| 294 | /* |
| 295 | * Selects the cipher, and keys if by computing the MD5 checksum of the |
| 296 | * passphrase and using the resulting 16 bytes as the key. |
| 297 | */ |
| 298 | |
| 299 | void |
| 300 | cipher_set_key_string(CipherContext *cc, Cipher *cipher, |
| 301 | const char *passphrase, int do_encrypt) |
| 302 | { |
| 303 | MD5_CTX md; |
| 304 | u_char digest[16]; |
| 305 | |
| 306 | MD5_Init(&md); |
| 307 | MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); |
| 308 | MD5_Final(digest, &md); |
| 309 | |
| 310 | cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); |
| 311 | |
| 312 | memset(digest, 0, sizeof(digest)); |
| 313 | memset(&md, 0, sizeof(md)); |
| 314 | } |
| 315 | |
| 316 | /* |
| 317 | * Exports an IV from the CipherContext required to export the key |
| 318 | * state back from the unprivileged child to the privileged parent |
| 319 | * process. |
| 320 | */ |
| 321 | |
| 322 | int |
| 323 | cipher_get_keyiv_len(const CipherContext *cc) |
| 324 | { |
| 325 | Cipher *c = cc->cipher; |
| 326 | int ivlen; |
| 327 | |
| 328 | if (c->number == SSH_CIPHER_3DES) |
| 329 | ivlen = 24; |
| 330 | else |
| 331 | ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); |
| 332 | return (ivlen); |
| 333 | } |
| 334 | |
| 335 | void |
| 336 | cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) |
| 337 | { |
| 338 | Cipher *c = cc->cipher; |
| 339 | int evplen; |
| 340 | |
| 341 | switch (c->number) { |
| 342 | case SSH_CIPHER_SSH2: |
| 343 | case SSH_CIPHER_DES: |
| 344 | case SSH_CIPHER_BLOWFISH: |
| 345 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); |
| 346 | if (evplen <= 0) |
| 347 | return; |
| 348 | if ((u_int)evplen != len) |
| 349 | fatal("%s: wrong iv length %d != %d", __func__, |
| 350 | evplen, len); |
| 351 | #ifdef USE_BUILTIN_RIJNDAEL |
| 352 | if (c->evptype == evp_rijndael) |
| 353 | ssh_rijndael_iv(&cc->evp, 0, iv, len); |
| 354 | else |
| 355 | #endif |
| 356 | if (c->evptype == evp_aes_128_ctr) |
| 357 | ssh_aes_ctr_iv(&cc->evp, 0, iv, len); |
| 358 | else |
| 359 | memcpy(iv, cc->evp.iv, len); |
| 360 | break; |
| 361 | case SSH_CIPHER_3DES: |
| 362 | ssh1_3des_iv(&cc->evp, 0, iv, 24); |
| 363 | break; |
| 364 | default: |
| 365 | fatal("%s: bad cipher %d", __func__, c->number); |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | void |
| 370 | cipher_set_keyiv(CipherContext *cc, u_char *iv) |
| 371 | { |
| 372 | Cipher *c = cc->cipher; |
| 373 | int evplen = 0; |
| 374 | |
| 375 | switch (c->number) { |
| 376 | case SSH_CIPHER_SSH2: |
| 377 | case SSH_CIPHER_DES: |
| 378 | case SSH_CIPHER_BLOWFISH: |
| 379 | evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); |
| 380 | if (evplen == 0) |
| 381 | return; |
| 382 | #ifdef USE_BUILTIN_RIJNDAEL |
| 383 | if (c->evptype == evp_rijndael) |
| 384 | ssh_rijndael_iv(&cc->evp, 1, iv, evplen); |
| 385 | else |
| 386 | #endif |
| 387 | if (c->evptype == evp_aes_128_ctr) |
| 388 | ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); |
| 389 | else |
| 390 | memcpy(cc->evp.iv, iv, evplen); |
| 391 | break; |
| 392 | case SSH_CIPHER_3DES: |
| 393 | ssh1_3des_iv(&cc->evp, 1, iv, 24); |
| 394 | break; |
| 395 | default: |
| 396 | fatal("%s: bad cipher %d", __func__, c->number); |
| 397 | } |
| 398 | } |
| 399 | |
| 400 | #if OPENSSL_VERSION_NUMBER < 0x00907000L |
| 401 | #define EVP_X_STATE(evp) &(evp).c |
| 402 | #define EVP_X_STATE_LEN(evp) sizeof((evp).c) |
| 403 | #else |
| 404 | #define EVP_X_STATE(evp) (evp).cipher_data |
| 405 | #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size |
| 406 | #endif |
| 407 | |
| 408 | int |
| 409 | cipher_get_keycontext(const CipherContext *cc, u_char *dat) |
| 410 | { |
| 411 | Cipher *c = cc->cipher; |
| 412 | int plen = 0; |
| 413 | |
| 414 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
| 415 | plen = EVP_X_STATE_LEN(cc->evp); |
| 416 | if (dat == NULL) |
| 417 | return (plen); |
| 418 | memcpy(dat, EVP_X_STATE(cc->evp), plen); |
| 419 | } |
| 420 | return (plen); |
| 421 | } |
| 422 | |
| 423 | void |
| 424 | cipher_set_keycontext(CipherContext *cc, u_char *dat) |
| 425 | { |
| 426 | Cipher *c = cc->cipher; |
| 427 | int plen; |
| 428 | |
| 429 | if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { |
| 430 | plen = EVP_X_STATE_LEN(cc->evp); |
| 431 | memcpy(EVP_X_STATE(cc->evp), dat, plen); |
| 432 | } |
| 433 | } |