/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file Data Channel Cryptography mbed TLS-specific backend interface
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif
#include "syshead.h"
#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
#include "errlevel.h"
#include "basic.h"
#include "buffer.h"
#include "integer.h"
#include "crypto_backend.h"
#include "otime.h"
#include "misc.h"
#include <mbedtls/des.h>
#include <mbedtls/error.h>
#include <mbedtls/md5.h>
#include <mbedtls/cipher.h>
#include <mbedtls/havege.h>
#include <mbedtls/entropy.h>
/*
*
* Hardware engine support. Allows loading/unloading of engines.
*
*/
void
crypto_init_lib_engine (const char *engine_name)
{
msg (M_WARN, "Note: mbed TLS hardware crypto engine functionality is not "
"available");
}
/*
*
* Functions related to the core crypto library
*
*/
void
crypto_init_lib (void)
{
}
void
crypto_uninit_lib (void)
{
}
void
crypto_clear_error (void)
{
}
bool mbed_log_err(unsigned int flags, int errval, const char *prefix)
{
if (0 != errval)
{
char errstr[256];
mbedtls_strerror(errval, errstr, sizeof(errstr));
if (NULL == prefix) prefix = "mbed TLS error";
msg (flags, "%s: %s", prefix, errstr);
}
return 0 == errval;
}
bool mbed_log_func_line(unsigned int flags, int errval, const char *func,
int line)
{
char prefix[256];
if (!openvpn_snprintf(prefix, sizeof(prefix), "%s:%d", func, line))
return mbed_log_err(flags, errval, func);
return mbed_log_err(flags, errval, prefix);
}
#ifdef DMALLOC
void
crypto_init_dmalloc (void)
{
msg (M_ERR, "Error: dmalloc support is not available for mbed TLS.");
}
#endif /* DMALLOC */
const cipher_name_pair cipher_name_translation_table[] = {
{ "BF-CBC", "BLOWFISH-CBC" },
{ "BF-CFB", "BLOWFISH-CFB64" },
{ "CAMELLIA-128-CFB", "CAMELLIA-128-CFB128" },
{ "CAMELLIA-192-CFB", "CAMELLIA-192-CFB128" },
{ "CAMELLIA-256-CFB", "CAMELLIA-256-CFB128" }
};
const size_t cipher_name_translation_table_count =
sizeof (cipher_name_translation_table) / sizeof (*cipher_name_translation_table);
void
show_available_ciphers ()
{
const int *ciphers = mbedtls_cipher_list();
#ifndef ENABLE_SMALL
printf ("The following ciphers and cipher modes are available for use\n"
"with " PACKAGE_NAME ". Each cipher shown below may be used as a\n"
"parameter to the --cipher option. Using a CBC or GCM mode is\n"
"recommended. In static key mode only CBC mode is allowed.\n\n");
#endif
while (*ciphers != 0)
{
const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers);
if (info && (cipher_kt_mode_cbc(info)
#ifdef HAVE_AEAD_CIPHER_MODES
|| cipher_kt_mode_aead(info)
#endif
))
{
const char *ssl_only = cipher_kt_mode_cbc(info) ?
"" : " (TLS client/server mode)";
printf ("%s %d bit default key%s\n",
cipher_kt_name(info), cipher_kt_key_size(info) * 8, ssl_only);
}
ciphers++;
}
printf ("\n");
}
void
show_available_digests ()
{
const int *digests = mbedtls_md_list();
#ifndef ENABLE_SMALL
printf ("The following message digests are available for use with\n"
PACKAGE_NAME ". A message digest is used in conjunction with\n"
"the HMAC function, to authenticate received packets.\n"
"You can specify a message digest as parameter to\n"
"the --auth option.\n\n");
#endif
while (*digests != 0)
{
const mbedtls_md_info_t *info = mbedtls_md_info_from_type(*digests);
if (info)
printf ("%s %d bit default key\n", mbedtls_md_get_name(info),
mbedtls_md_get_size(info) * 8);
digests++;
}
printf ("\n");
}
void
show_available_engines ()
{
printf ("Sorry, mbed TLS hardware crypto engine functionality is not "
"available\n");
}
/*
*
* Random number functions, used in cases where we want
* reasonably strong cryptographic random number generation
* without depleting our entropy pool. Used for random
* IV values and a number of other miscellaneous tasks.
*
*/
/*
* Initialise the given ctr_drbg context, using a personalisation string and an
* entropy gathering function.
*/
mbedtls_ctr_drbg_context * rand_ctx_get()
{
static mbedtls_entropy_context ec = {0};
static mbedtls_ctr_drbg_context cd_ctx = {0};
static bool rand_initialised = false;
if (!rand_initialised)
{
struct gc_arena gc = gc_new();
struct buffer pers_string = alloc_buf_gc(100, &gc);
/*
* Personalisation string, should be as unique as possible (see NIST
* 800-90 section 8.7.1). We have very little information at this stage.
* Include Program Name, memory address of the context and PID.
*/
buf_printf(&pers_string, "OpenVPN %0u %p %s", platform_getpid(), &cd_ctx, time_string(0, 0, 0, &gc));
/* Initialise mbed TLS RNG, and built-in entropy sources */
mbedtls_entropy_init(&ec);
mbedtls_ctr_drbg_init(&cd_ctx);
if (!mbed_ok(mbedtls_ctr_drbg_seed(&cd_ctx, mbedtls_entropy_func, &ec,
BPTR(&pers_string), BLEN(&pers_string))))
msg (M_FATAL, "Failed to initialize random generator");
gc_free(&gc);
rand_initialised = true;
}
return &cd_ctx;
}
#ifdef ENABLE_PREDICTION_RESISTANCE
void rand_ctx_enable_prediction_resistance()
{
mbedtls_ctr_drbg_context *cd_ctx = rand_ctx_get();
mbedtls_ctr_drbg_set_prediction_resistance(cd_ctx, 1);
}
#endif /* ENABLE_PREDICTION_RESISTANCE */
int
rand_bytes (uint8_t *output, int len)
{
mbedtls_ctr_drbg_context *rng_ctx = rand_ctx_get();
while (len > 0)
{
const size_t blen = min_int (len, MBEDTLS_CTR_DRBG_MAX_REQUEST);
if (0 != mbedtls_ctr_drbg_random(rng_ctx, output, blen))
return 0;
output += blen;
len -= blen;
}
return 1;
}
/*
*
* Key functions, allow manipulation of keys.
*
*/
int
key_des_num_cblocks (const mbedtls_cipher_info_t *kt)
{
int ret = 0;
if (kt->type == MBEDTLS_CIPHER_DES_CBC)
ret = 1;
if (kt->type == MBEDTLS_CIPHER_DES_EDE_CBC)
ret = 2;
if (kt->type == MBEDTLS_CIPHER_DES_EDE3_CBC)
ret = 3;
dmsg (D_CRYPTO_DEBUG, "CRYPTO INFO: n_DES_cblocks=%d", ret);
return ret;
}
bool
key_des_check (uint8_t *key, int key_len, int ndc)
{
int i;
struct buffer b;
buf_set_read (&b, key, key_len);
for (i = 0; i < ndc; ++i)
{
unsigned char *key = buf_read_alloc(&b, MBEDTLS_DES_KEY_SIZE);
if (!key)
{
msg (D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: insufficient key material");
goto err;
}
if (0 != mbedtls_des_key_check_weak(key))
{
msg (D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: weak key detected");
goto err;
}
if (0 != mbedtls_des_key_check_key_parity(key))
{
msg (D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: bad parity detected");
goto err;
}
}
return true;
err:
return false;
}
void
key_des_fixup (uint8_t *key, int key_len, int ndc)
{
int i;
struct buffer b;
buf_set_read (&b, key, key_len);
for (i = 0; i < ndc; ++i)
{
unsigned char *key = buf_read_alloc(&b, MBEDTLS_DES_KEY_SIZE);
if (!key)
{
msg (D_CRYPT_ERRORS, "CRYPTO INFO: fixup_key_DES: insufficient key material");
return;
}
mbedtls_des_key_set_parity(key);
}
}
/*
*
* Generic cipher key type functions
*
*/
const mbedtls_cipher_info_t *
cipher_kt_get (const char *ciphername)
{
const mbedtls_cipher_info_t *cipher = NULL;
ASSERT (ciphername);
cipher = mbedtls_cipher_info_from_string(ciphername);
if (NULL == cipher)
msg (M_FATAL, "Cipher algorithm '%s' not found", ciphername);
if (cipher->key_bitlen/8 > MAX_CIPHER_KEY_LENGTH)
msg (M_FATAL, "Cipher algorithm '%s' uses a default key size (%d bytes) which is larger than " PACKAGE_NAME "'s current maximum key size (%d bytes)",
ciphername,
cipher->key_bitlen/8,
MAX_CIPHER_KEY_LENGTH);
return cipher;
}
const char *
cipher_kt_name (const mbedtls_cipher_info_t *cipher_kt)
{
if (NULL == cipher_kt)
return "[null-cipher]";
return translate_cipher_name_to_openvpn(cipher_kt->name);
}
int
cipher_kt_key_size (const mbedtls_cipher_info_t *cipher_kt)
{
if (NULL == cipher_kt)
return 0;
return cipher_kt->key_bitlen/8;
}
int
cipher_kt_iv_size (const mbedtls_cipher_info_t *cipher_kt)
{
if (NULL == cipher_kt)
return 0;
return cipher_kt->iv_size;
}
int
cipher_kt_block_size (const mbedtls_cipher_info_t *cipher_kt)
{
if (NULL == cipher_kt)
return 0;
return cipher_kt->block_size;
}
int
cipher_kt_tag_size (const mbedtls_cipher_info_t *cipher_kt)
{
#ifdef HAVE_AEAD_CIPHER_MODES
if (cipher_kt && cipher_kt_mode_aead(cipher_kt))
return OPENVPN_AEAD_TAG_LENGTH;
#endif
return 0;
}
int
cipher_kt_mode (const mbedtls_cipher_info_t *cipher_kt)
{
ASSERT(NULL != cipher_kt);
return cipher_kt->mode;
}
bool
cipher_kt_mode_cbc(const cipher_kt_t *cipher)
{
return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_CBC;
}
bool
cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher)
{
return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_OFB ||
cipher_kt_mode(cipher) == OPENVPN_MODE_CFB);
}
bool
cipher_kt_mode_aead(const cipher_kt_t *cipher)
{
return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_GCM;
}
/*
*
* Generic cipher context functions
*
*/
void
cipher_ctx_init (mbedtls_cipher_context_t *ctx, uint8_t *key, int key_len,
const mbedtls_cipher_info_t *kt, const mbedtls_operation_t operation)
{
ASSERT(NULL != kt && NULL != ctx);
CLEAR (*ctx);
if (!mbed_ok(mbedtls_cipher_setup(ctx, kt)))
msg (M_FATAL, "mbed TLS cipher context init #1");
if (!mbed_ok(mbedtls_cipher_setkey(ctx, key, key_len*8, operation)))
msg (M_FATAL, "mbed TLS cipher set key");
/* make sure we used a big enough key */
ASSERT (ctx->key_bitlen <= key_len*8);
}
void cipher_ctx_cleanup (mbedtls_cipher_context_t *ctx)
{
mbedtls_cipher_free(ctx);
}
int cipher_ctx_iv_length (const mbedtls_cipher_context_t *ctx)
{
return mbedtls_cipher_get_iv_size(ctx);
}
int cipher_ctx_get_tag (cipher_ctx_t *ctx, uint8_t* tag, int tag_len)
{
#ifdef HAVE_AEAD_CIPHER_MODES
if (tag_len > SIZE_MAX)
return 0;
if (!mbed_ok (mbedtls_cipher_write_tag (ctx, (unsigned char *) tag, tag_len)))
return 0;
return 1;
#else
ASSERT(0);
#endif /* HAVE_AEAD_CIPHER_MODES */
}
int cipher_ctx_block_size(const mbedtls_cipher_context_t *ctx)
{
return mbedtls_cipher_get_block_size(ctx);
}
int cipher_ctx_mode (const mbedtls_cipher_context_t *ctx)
{
ASSERT(NULL != ctx);
return cipher_kt_mode(ctx->cipher_info);
}
const cipher_kt_t *
cipher_ctx_get_cipher_kt (const cipher_ctx_t *ctx)
{
return ctx ? ctx->cipher_info : NULL;
}
int cipher_ctx_reset (mbedtls_cipher_context_t *ctx, uint8_t *iv_buf)
{
if (!mbed_ok(mbedtls_cipher_reset(ctx)))
return 0;
if (!mbed_ok(mbedtls_cipher_set_iv(ctx, iv_buf, ctx->cipher_info->iv_size)))
return 0;
return 1;
}
int cipher_ctx_update_ad (cipher_ctx_t *ctx, const uint8_t *src, int src_len)
{
#ifdef HAVE_AEAD_CIPHER_MODES
if (src_len > SIZE_MAX)
return 0;
if (!mbed_ok (mbedtls_cipher_update_ad (ctx, src, src_len)))
return 0;
return 1;
#else
ASSERT(0);
#endif /* HAVE_AEAD_CIPHER_MODES */
}
int cipher_ctx_update (mbedtls_cipher_context_t *ctx, uint8_t *dst,
int *dst_len, uint8_t *src, int src_len)
{
size_t s_dst_len = *dst_len;
if (!mbed_ok(mbedtls_cipher_update(ctx, src, (size_t) src_len, dst,
&s_dst_len)))
return 0;
*dst_len = s_dst_len;
return 1;
}
int cipher_ctx_final (mbedtls_cipher_context_t *ctx, uint8_t *dst, int *dst_len)
{
size_t s_dst_len = *dst_len;
if (!mbed_ok(mbedtls_cipher_finish(ctx, dst, &s_dst_len)))
return 0;
*dst_len = s_dst_len;
return 1;
}
int cipher_ctx_final_check_tag (mbedtls_cipher_context_t *ctx, uint8_t *dst,
int *dst_len, uint8_t *tag, size_t tag_len)
{
#ifdef HAVE_AEAD_CIPHER_MODES
size_t olen = 0;
if (MBEDTLS_DECRYPT != ctx->operation)
return 0;
if (tag_len > SIZE_MAX)
return 0;
if (!mbed_ok (mbedtls_cipher_finish (ctx, dst, &olen)))
{
msg (D_CRYPT_ERRORS, "%s: cipher_ctx_final() failed", __func__);
return 0;
}
if (olen > INT_MAX)
return 0;
*dst_len = olen;
if (!mbed_ok (mbedtls_cipher_check_tag (ctx, (const unsigned char *) tag,
tag_len)))
return 0;
return 1;
#else
ASSERT(0);
#endif /* HAVE_AEAD_CIPHER_MODES */
}
void
cipher_des_encrypt_ecb (const unsigned char key[DES_KEY_LENGTH],
unsigned char *src,
unsigned char *dst)
{
mbedtls_des_context ctx;
ASSERT (mbed_ok(mbedtls_des_setkey_enc(&ctx, key)));
ASSERT (mbed_ok(mbedtls_des_crypt_ecb(&ctx, src, dst)));
}
/*
*
* Generic message digest information functions
*
*/
const mbedtls_md_info_t *
md_kt_get (const char *digest)
{
const mbedtls_md_info_t *md = NULL;
ASSERT (digest);
md = mbedtls_md_info_from_string(digest);
if (!md)
msg (M_FATAL, "Message hash algorithm '%s' not found", digest);
if (mbedtls_md_get_size(md) > MAX_HMAC_KEY_LENGTH)
msg (M_FATAL, "Message hash algorithm '%s' uses a default hash size (%d bytes) which is larger than " PACKAGE_NAME "'s current maximum hash size (%d bytes)",
digest,
mbedtls_md_get_size(md),
MAX_HMAC_KEY_LENGTH);
return md;
}
const char *
md_kt_name (const mbedtls_md_info_t *kt)
{
if (NULL == kt)
return "[null-digest]";
return mbedtls_md_get_name (kt);
}
int
md_kt_size (const mbedtls_md_info_t *kt)
{
if (NULL == kt)
return 0;
return mbedtls_md_get_size(kt);
}
/*
*
* Generic message digest functions
*
*/
int
md_full (const md_kt_t *kt, const uint8_t *src, int src_len, uint8_t *dst)
{
return 0 == mbedtls_md(kt, src, src_len, dst);
}
void
md_ctx_init (mbedtls_md_context_t *ctx, const mbedtls_md_info_t *kt)
{
ASSERT(NULL != ctx && NULL != kt);
mbedtls_md_init(ctx);
ASSERT(0 == mbedtls_md_setup(ctx, kt, 0));
ASSERT(0 == mbedtls_md_starts(ctx));
}
void
md_ctx_cleanup(mbedtls_md_context_t *ctx)
{
}
int
md_ctx_size (const mbedtls_md_context_t *ctx)
{
if (NULL == ctx)
return 0;
return mbedtls_md_get_size(ctx->md_info);
}
void
md_ctx_update (mbedtls_md_context_t *ctx, const uint8_t *src, int src_len)
{
ASSERT(0 == mbedtls_md_update(ctx, src, src_len));
}
void
md_ctx_final (mbedtls_md_context_t *ctx, uint8_t *dst)
{
ASSERT(0 == mbedtls_md_finish(ctx, dst));
mbedtls_md_free(ctx);
}
/*
*
* Generic HMAC functions
*
*/
/*
* TODO: re-enable dmsg for crypto debug
*/
void
hmac_ctx_init (mbedtls_md_context_t *ctx, const uint8_t *key, int key_len,
const mbedtls_md_info_t *kt)
{
ASSERT(NULL != kt && NULL != ctx);
mbedtls_md_init(ctx);
ASSERT(0 == mbedtls_md_setup(ctx, kt, 1));
ASSERT(0 == mbedtls_md_hmac_starts(ctx, key, key_len));
/* make sure we used a big enough key */
ASSERT (mbedtls_md_get_size(kt) <= key_len);
}
void
hmac_ctx_cleanup(mbedtls_md_context_t *ctx)
{
mbedtls_md_free(ctx);
}
int
hmac_ctx_size (const mbedtls_md_context_t *ctx)
{
if (NULL == ctx)
return 0;
return mbedtls_md_get_size(ctx->md_info);
}
void
hmac_ctx_reset (mbedtls_md_context_t *ctx)
{
ASSERT(0 == mbedtls_md_hmac_reset(ctx));
}
void
hmac_ctx_update (mbedtls_md_context_t *ctx, const uint8_t *src, int src_len)
{
ASSERT(0 == mbedtls_md_hmac_update(ctx, src, src_len));
}
void
hmac_ctx_final (mbedtls_md_context_t *ctx, uint8_t *dst)
{
ASSERT(0 == mbedtls_md_hmac_finish(ctx, dst));
}
#endif /* ENABLE_CRYPTO && ENABLE_CRYPTO_MBEDTLS */