diff options
Diffstat (limited to 'crypto/openssh/cipher.c')
| -rw-r--r-- | crypto/openssh/cipher.c | 585 |
1 files changed, 585 insertions, 0 deletions
diff --git a/crypto/openssh/cipher.c b/crypto/openssh/cipher.c new file mode 100644 index 000000000000..0f4bd48e60c9 --- /dev/null +++ b/crypto/openssh/cipher.c @@ -0,0 +1,585 @@ +/* $OpenBSD: cipher.c,v 1.97 2014/02/07 06:55:54 djm Exp $ */ +/* $FreeBSD$ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + * + * + * Copyright (c) 1999 Niels Provos. All rights reserved. + * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" +__RCSID("$FreeBSD$"); + +#include <sys/types.h> + +#include <string.h> +#include <stdarg.h> +#include <stdio.h> + +#include "xmalloc.h" +#include "log.h" +#include "misc.h" +#include "cipher.h" +#include "buffer.h" +#include "digest.h" + +/* compatibility with old or broken OpenSSL versions */ +#include "openbsd-compat/openssl-compat.h" + +extern const EVP_CIPHER *evp_ssh1_bf(void); +extern const EVP_CIPHER *evp_ssh1_3des(void); +extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); + +struct Cipher { + char *name; + int number; /* for ssh1 only */ + u_int block_size; + u_int key_len; + u_int iv_len; /* defaults to block_size */ + u_int auth_len; + u_int discard_len; + u_int flags; +#define CFLAG_CBC (1<<0) +#define CFLAG_CHACHAPOLY (1<<1) + const EVP_CIPHER *(*evptype)(void); +}; + +static const struct Cipher ciphers[] = { + { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null }, + { "des", SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc }, + { "3des", SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des }, + { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf }, + + { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc }, + { "blowfish-cbc", + SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc }, + { "cast128-cbc", + SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc }, + { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 }, + { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 }, + { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 }, + { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc }, + { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc }, + { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc }, + { "rijndael-cbc@lysator.liu.se", + SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc }, + { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr }, + { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr }, + { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr }, +#ifdef OPENSSL_HAVE_EVPGCM + { "aes128-gcm@openssh.com", + SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm }, + { "aes256-gcm@openssh.com", + SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm }, +#endif + { "chacha20-poly1305@openssh.com", + SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL }, + { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL } +}; + +/*--*/ + +/* Returns a list of supported ciphers separated by the specified char. */ +char * +cipher_alg_list(char sep, int auth_only) +{ + char *ret = NULL; + size_t nlen, rlen = 0; + const Cipher *c; + + for (c = ciphers; c->name != NULL; c++) { + if (c->number != SSH_CIPHER_SSH2) + continue; + if (auth_only && c->auth_len == 0) + continue; + if (ret != NULL) + ret[rlen++] = sep; + nlen = strlen(c->name); + ret = xrealloc(ret, 1, rlen + nlen + 2); + memcpy(ret + rlen, c->name, nlen + 1); + rlen += nlen; + } + return ret; +} + +u_int +cipher_blocksize(const Cipher *c) +{ + return (c->block_size); +} + +u_int +cipher_keylen(const Cipher *c) +{ + return (c->key_len); +} + +u_int +cipher_seclen(const Cipher *c) +{ + if (strcmp("3des-cbc", c->name) == 0) + return 14; + return cipher_keylen(c); +} + +u_int +cipher_authlen(const Cipher *c) +{ + return (c->auth_len); +} + +u_int +cipher_ivlen(const Cipher *c) +{ + /* + * Default is cipher block size, except for chacha20+poly1305 that + * needs no IV. XXX make iv_len == -1 default? + */ + return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ? + c->iv_len : c->block_size; +} + +u_int +cipher_get_number(const Cipher *c) +{ + return (c->number); +} + +u_int +cipher_is_cbc(const Cipher *c) +{ + return (c->flags & CFLAG_CBC) != 0; +} + +u_int +cipher_mask_ssh1(int client) +{ + u_int mask = 0; + mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ + mask |= 1 << SSH_CIPHER_BLOWFISH; + if (client) { + mask |= 1 << SSH_CIPHER_DES; + } + return mask; +} + +const Cipher * +cipher_by_name(const char *name) +{ + const Cipher *c; + for (c = ciphers; c->name != NULL; c++) + if (strcmp(c->name, name) == 0) + return c; + return NULL; +} + +const Cipher * +cipher_by_number(int id) +{ + const Cipher *c; + for (c = ciphers; c->name != NULL; c++) + if (c->number == id) + return c; + return NULL; +} + +#define CIPHER_SEP "," +int +ciphers_valid(const char *names) +{ + const Cipher *c; + char *cipher_list, *cp; + char *p; + + if (names == NULL || strcmp(names, "") == 0) + return 0; + cipher_list = cp = xstrdup(names); + for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; + (p = strsep(&cp, CIPHER_SEP))) { + c = cipher_by_name(p); +#ifdef NONE_CIPHER_ENABLED + if (c == NULL || (c->number != SSH_CIPHER_SSH2 && + c->number != SSH_CIPHER_NONE)) { +#else + if (c == NULL || (c->number != SSH_CIPHER_SSH2)) { +#endif + debug("bad cipher %s [%s]", p, names); + free(cipher_list); + return 0; + } + } + debug3("ciphers ok: [%s]", names); + free(cipher_list); + return 1; +} + +/* + * Parses the name of the cipher. Returns the number of the corresponding + * cipher, or -1 on error. + */ + +int +cipher_number(const char *name) +{ + const Cipher *c; + if (name == NULL) + return -1; + for (c = ciphers; c->name != NULL; c++) + if (strcasecmp(c->name, name) == 0) + return c->number; + return -1; +} + +char * +cipher_name(int id) +{ + const Cipher *c = cipher_by_number(id); + return (c==NULL) ? "<unknown>" : c->name; +} + +void +cipher_init(CipherContext *cc, const Cipher *cipher, + const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, + int do_encrypt) +{ + static int dowarn = 1; +#ifdef SSH_OLD_EVP + EVP_CIPHER *type; +#else + const EVP_CIPHER *type; + int klen; +#endif + u_char *junk, *discard; + + if (cipher->number == SSH_CIPHER_DES) { + if (dowarn) { + error("Warning: use of DES is strongly discouraged " + "due to cryptographic weaknesses"); + dowarn = 0; + } + if (keylen > 8) + keylen = 8; + } + cc->plaintext = (cipher->number == SSH_CIPHER_NONE); + cc->encrypt = do_encrypt; + + if (keylen < cipher->key_len) + fatal("cipher_init: key length %d is insufficient for %s.", + keylen, cipher->name); + if (iv != NULL && ivlen < cipher_ivlen(cipher)) + fatal("cipher_init: iv length %d is insufficient for %s.", + ivlen, cipher->name); + cc->cipher = cipher; + + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) { + chachapoly_init(&cc->cp_ctx, key, keylen); + return; + } + type = (*cipher->evptype)(); + EVP_CIPHER_CTX_init(&cc->evp); +#ifdef SSH_OLD_EVP + if (type->key_len > 0 && type->key_len != keylen) { + debug("cipher_init: set keylen (%d -> %d)", + type->key_len, keylen); + type->key_len = keylen; + } + EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, + (do_encrypt == CIPHER_ENCRYPT)); +#else + if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, + (do_encrypt == CIPHER_ENCRYPT)) == 0) + fatal("cipher_init: EVP_CipherInit failed for %s", + cipher->name); + if (cipher_authlen(cipher) && + !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED, + -1, (u_char *)iv)) + fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s", + cipher->name); + klen = EVP_CIPHER_CTX_key_length(&cc->evp); + if (klen > 0 && keylen != (u_int)klen) { + debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); + if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) + fatal("cipher_init: set keylen failed (%d -> %d)", + klen, keylen); + } + if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) + fatal("cipher_init: EVP_CipherInit: set key failed for %s", + cipher->name); +#endif + + if (cipher->discard_len > 0) { + junk = xmalloc(cipher->discard_len); + discard = xmalloc(cipher->discard_len); + if (EVP_Cipher(&cc->evp, discard, junk, + cipher->discard_len) == 0) + fatal("evp_crypt: EVP_Cipher failed during discard"); + explicit_bzero(discard, cipher->discard_len); + free(junk); + free(discard); + } +} + +/* + * cipher_crypt() operates as following: + * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'. + * Theses bytes are treated as additional authenticated data for + * authenticated encryption modes. + * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'. + * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag. + * This tag is written on encryption and verified on decryption. + * Both 'aadlen' and 'authlen' can be set to 0. + * cipher_crypt() returns 0 on success and -1 if the decryption integrity + * check fails. + */ +int +cipher_crypt(CipherContext *cc, u_int seqnr, u_char *dest, const u_char *src, + u_int len, u_int aadlen, u_int authlen) +{ + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) + return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src, len, + aadlen, authlen, cc->encrypt); + if (authlen) { + u_char lastiv[1]; + + if (authlen != cipher_authlen(cc->cipher)) + fatal("%s: authlen mismatch %d", __func__, authlen); + /* increment IV */ + if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN, + 1, lastiv)) + fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__); + /* set tag on decyption */ + if (!cc->encrypt && + !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG, + authlen, (u_char *)src + aadlen + len)) + fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__); + } + if (aadlen) { + if (authlen && + EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0) + fatal("%s: EVP_Cipher(aad) failed", __func__); + memcpy(dest, src, aadlen); + } + if (len % cc->cipher->block_size) + fatal("%s: bad plaintext length %d", __func__, len); + if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen, + len) < 0) + fatal("%s: EVP_Cipher failed", __func__); + if (authlen) { + /* compute tag (on encrypt) or verify tag (on decrypt) */ + if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0) { + if (cc->encrypt) + fatal("%s: EVP_Cipher(final) failed", __func__); + else + return -1; + } + if (cc->encrypt && + !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG, + authlen, dest + aadlen + len)) + fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__); + } + return 0; +} + +/* Extract the packet length, including any decryption necessary beforehand */ +int +cipher_get_length(CipherContext *cc, u_int *plenp, u_int seqnr, + const u_char *cp, u_int len) +{ + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) + return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr, + cp, len); + if (len < 4) + return -1; + *plenp = get_u32(cp); + return 0; +} + +void +cipher_cleanup(CipherContext *cc) +{ + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) + explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx)); + else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) + error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); +} + +/* + * Selects the cipher, and keys if by computing the MD5 checksum of the + * passphrase and using the resulting 16 bytes as the key. + */ + +void +cipher_set_key_string(CipherContext *cc, const Cipher *cipher, + const char *passphrase, int do_encrypt) +{ + u_char digest[16]; + + if (ssh_digest_memory(SSH_DIGEST_MD5, passphrase, strlen(passphrase), + digest, sizeof(digest)) < 0) + fatal("%s: md5 failed", __func__); + + cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); + + explicit_bzero(digest, sizeof(digest)); +} + +/* + * Exports an IV from the CipherContext required to export the key + * state back from the unprivileged child to the privileged parent + * process. + */ + +int +cipher_get_keyiv_len(const CipherContext *cc) +{ + const Cipher *c = cc->cipher; + int ivlen; + + if (c->number == SSH_CIPHER_3DES) + ivlen = 24; + else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) + ivlen = 0; + else + ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); + return (ivlen); +} + +void +cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) +{ + const Cipher *c = cc->cipher; + int evplen; + + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) { + if (len != 0) + fatal("%s: wrong iv length %d != %d", __func__, len, 0); + return; + } + + switch (c->number) { +#ifdef NONE_CIPHER_ENABLED + case SSH_CIPHER_NONE: +#endif + case SSH_CIPHER_SSH2: + case SSH_CIPHER_DES: + case SSH_CIPHER_BLOWFISH: + evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); + if (evplen <= 0) + return; + if ((u_int)evplen != len) + fatal("%s: wrong iv length %d != %d", __func__, + evplen, len); +#ifdef USE_BUILTIN_RIJNDAEL + if (c->evptype == evp_rijndael) + ssh_rijndael_iv(&cc->evp, 0, iv, len); + else +#endif +#ifndef OPENSSL_HAVE_EVPCTR + if (c->evptype == evp_aes_128_ctr) + ssh_aes_ctr_iv(&cc->evp, 0, iv, len); + else +#endif + memcpy(iv, cc->evp.iv, len); + break; + case SSH_CIPHER_3DES: + ssh1_3des_iv(&cc->evp, 0, iv, 24); + break; + default: + fatal("%s: bad cipher %d", __func__, c->number); + } +} + +void +cipher_set_keyiv(CipherContext *cc, u_char *iv) +{ + const Cipher *c = cc->cipher; + int evplen = 0; + + if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) + return; + + switch (c->number) { +#ifdef NONE_CIPHER_ENABLED + case SSH_CIPHER_NONE: +#endif + case SSH_CIPHER_SSH2: + case SSH_CIPHER_DES: + case SSH_CIPHER_BLOWFISH: + evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); + if (evplen == 0) + return; +#ifdef USE_BUILTIN_RIJNDAEL + if (c->evptype == evp_rijndael) + ssh_rijndael_iv(&cc->evp, 1, iv, evplen); + else +#endif +#ifndef OPENSSL_HAVE_EVPCTR + if (c->evptype == evp_aes_128_ctr) + ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); + else +#endif + memcpy(cc->evp.iv, iv, evplen); + break; + case SSH_CIPHER_3DES: + ssh1_3des_iv(&cc->evp, 1, iv, 24); + break; + default: + fatal("%s: bad cipher %d", __func__, c->number); + } +} + +int +cipher_get_keycontext(const CipherContext *cc, u_char *dat) +{ + const Cipher *c = cc->cipher; + int plen = 0; + + if (c->evptype == EVP_rc4) { + plen = EVP_X_STATE_LEN(cc->evp); + if (dat == NULL) + return (plen); + memcpy(dat, EVP_X_STATE(cc->evp), plen); + } + return (plen); +} + +void +cipher_set_keycontext(CipherContext *cc, u_char *dat) +{ + const Cipher *c = cc->cipher; + int plen; + + if (c->evptype == EVP_rc4) { + plen = EVP_X_STATE_LEN(cc->evp); + memcpy(EVP_X_STATE(cc->evp), dat, plen); + } +} |