mbedtls/programs/pkey/dh_server.c
Gilles Peskine 377a310da4 Catch failures of AES or DES operations
Declare all AES and DES functions that return int as needing to have
their result checked, and do check the result in our code.

A DES or AES block operation can fail in alternative implementations of
mbedtls_internal_aes_encrypt() (under MBEDTLS_AES_ENCRYPT_ALT),
mbedtls_internal_aes_decrypt() (under MBEDTLS_AES_DECRYPT_ALT),
mbedtls_des_crypt_ecb() (under MBEDTLS_DES_CRYPT_ECB_ALT),
mbedtls_des3_crypt_ecb() (under MBEDTLS_DES3_CRYPT_ECB_ALT).
A failure can happen if the accelerator peripheral is in a bad state.
Several block modes were not catching the error.

This commit does the following code changes, grouped together to avoid
having an intermediate commit where the build fails:

* Add MBEDTLS_CHECK_RETURN to all functions returning int in aes.h and des.h.
* Fix all places where this causes a GCC warning, indicating that our code
  was not properly checking the result of an AES operation:
    * In library code: on failure, goto exit and return ret.
    * In pkey programs: goto exit.
    * In the benchmark program: exit (not ideal since there's no error
      message, but it's what the code currently does for failures).
    * In test code: TEST_ASSERT.
* Changelog entry.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-09-29 20:40:31 +02:00

340 lines
10 KiB
C

/*
* Diffie-Hellman-Merkle key exchange (server side)
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#include <stdlib.h>
#define mbedtls_printf printf
#define mbedtls_time_t time_t
#define mbedtls_exit exit
#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif /* MBEDTLS_PLATFORM_C */
#if defined(MBEDTLS_AES_C) && defined(MBEDTLS_DHM_C) && \
defined(MBEDTLS_ENTROPY_C) && defined(MBEDTLS_NET_C) && \
defined(MBEDTLS_RSA_C) && defined(MBEDTLS_SHA256_C) && \
defined(MBEDTLS_FS_IO) && defined(MBEDTLS_CTR_DRBG_C) && \
defined(MBEDTLS_SHA1_C)
#include "mbedtls/net_sockets.h"
#include "mbedtls/aes.h"
#include "mbedtls/dhm.h"
#include "mbedtls/rsa.h"
#include "mbedtls/sha1.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include <stdio.h>
#include <string.h>
#endif
#define SERVER_PORT "11999"
#define PLAINTEXT "==Hello there!=="
#if !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_DHM_C) || \
!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NET_C) || \
!defined(MBEDTLS_RSA_C) || !defined(MBEDTLS_SHA256_C) || \
!defined(MBEDTLS_FS_IO) || !defined(MBEDTLS_CTR_DRBG_C) || \
!defined(MBEDTLS_SHA1_C)
int main( void )
{
mbedtls_printf("MBEDTLS_AES_C and/or MBEDTLS_DHM_C and/or MBEDTLS_ENTROPY_C "
"and/or MBEDTLS_NET_C and/or MBEDTLS_RSA_C and/or "
"MBEDTLS_SHA256_C and/or MBEDTLS_FS_IO and/or "
"MBEDTLS_CTR_DRBG_C not defined.\n");
mbedtls_exit( 0 );
}
#else
int main( void )
{
FILE *f;
int ret = 1;
int exit_code = MBEDTLS_EXIT_FAILURE;
size_t n, buflen;
mbedtls_net_context listen_fd, client_fd;
unsigned char buf[2048];
unsigned char hash[32];
unsigned char buf2[2];
const char *pers = "dh_server";
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_rsa_context rsa;
mbedtls_dhm_context dhm;
mbedtls_aes_context aes;
mbedtls_mpi N, P, Q, D, E;
mbedtls_net_init( &listen_fd );
mbedtls_net_init( &client_fd );
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, MBEDTLS_MD_SHA256 );
mbedtls_dhm_init( &dhm );
mbedtls_aes_init( &aes );
mbedtls_ctr_drbg_init( &ctr_drbg );
mbedtls_mpi_init( &N ); mbedtls_mpi_init( &P ); mbedtls_mpi_init( &Q );
mbedtls_mpi_init( &D ); mbedtls_mpi_init( &E );
/*
* 1. Setup the RNG
*/
mbedtls_printf( "\n . Seeding the random number generator" );
fflush( stdout );
mbedtls_entropy_init( &entropy );
if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
(const unsigned char *) pers,
strlen( pers ) ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret );
goto exit;
}
/*
* 2a. Read the server's private RSA key
*/
mbedtls_printf( "\n . Reading private key from rsa_priv.txt" );
fflush( stdout );
if( ( f = fopen( "rsa_priv.txt", "rb" ) ) == NULL )
{
mbedtls_printf( " failed\n ! Could not open rsa_priv.txt\n" \
" ! Please run rsa_genkey first\n\n" );
goto exit;
}
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
if( ( ret = mbedtls_mpi_read_file( &N , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &E , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &D , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &P , 16, f ) ) != 0 ||
( ret = mbedtls_mpi_read_file( &Q , 16, f ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_mpi_read_file returned %d\n\n",
ret );
fclose( f );
goto exit;
}
fclose( f );
if( ( ret = mbedtls_rsa_import( &rsa, &N, &P, &Q, &D, &E ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_rsa_import returned %d\n\n",
ret );
goto exit;
}
if( ( ret = mbedtls_rsa_complete( &rsa ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_rsa_complete returned %d\n\n",
ret );
goto exit;
}
/*
* 2b. Get the DHM modulus and generator
*/
mbedtls_printf( "\n . Reading DH parameters from dh_prime.txt" );
fflush( stdout );
if( ( f = fopen( "dh_prime.txt", "rb" ) ) == NULL )
{
mbedtls_printf( " failed\n ! Could not open dh_prime.txt\n" \
" ! Please run dh_genprime first\n\n" );
goto exit;
}
if( mbedtls_mpi_read_file( &dhm.P, 16, f ) != 0 ||
mbedtls_mpi_read_file( &dhm.G, 16, f ) != 0 )
{
mbedtls_printf( " failed\n ! Invalid DH parameter file\n\n" );
fclose( f );
goto exit;
}
fclose( f );
/*
* 3. Wait for a client to connect
*/
mbedtls_printf( "\n . Waiting for a remote connection" );
fflush( stdout );
if( ( ret = mbedtls_net_bind( &listen_fd, NULL, SERVER_PORT, MBEDTLS_NET_PROTO_TCP ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_bind returned %d\n\n", ret );
goto exit;
}
if( ( ret = mbedtls_net_accept( &listen_fd, &client_fd,
NULL, 0, NULL ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_net_accept returned %d\n\n", ret );
goto exit;
}
/*
* 4. Setup the DH parameters (P,G,Ys)
*/
mbedtls_printf( "\n . Sending the server's DH parameters" );
fflush( stdout );
memset( buf, 0, sizeof( buf ) );
if( ( ret = mbedtls_dhm_make_params( &dhm, (int) mbedtls_mpi_size( &dhm.P ), buf, &n,
mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_dhm_make_params returned %d\n\n", ret );
goto exit;
}
/*
* 5. Sign the parameters and send them
*/
if( ( ret = mbedtls_sha1_ret( buf, n, hash ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_sha1_ret returned %d\n\n", ret );
goto exit;
}
buf[n ] = (unsigned char)( rsa.len >> 8 );
buf[n + 1] = (unsigned char)( rsa.len );
if( ( ret = mbedtls_rsa_pkcs1_sign( &rsa, NULL, NULL, MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA256,
0, hash, buf + n + 2 ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_rsa_pkcs1_sign returned %d\n\n", ret );
goto exit;
}
buflen = n + 2 + rsa.len;
buf2[0] = (unsigned char)( buflen >> 8 );
buf2[1] = (unsigned char)( buflen );
if( ( ret = mbedtls_net_send( &client_fd, buf2, 2 ) ) != 2 ||
( ret = mbedtls_net_send( &client_fd, buf, buflen ) ) != (int) buflen )
{
mbedtls_printf( " failed\n ! mbedtls_net_send returned %d\n\n", ret );
goto exit;
}
/*
* 6. Get the client's public value: Yc = G ^ Xc mod P
*/
mbedtls_printf( "\n . Receiving the client's public value" );
fflush( stdout );
memset( buf, 0, sizeof( buf ) );
n = dhm.len;
if( ( ret = mbedtls_net_recv( &client_fd, buf, n ) ) != (int) n )
{
mbedtls_printf( " failed\n ! mbedtls_net_recv returned %d\n\n", ret );
goto exit;
}
if( ( ret = mbedtls_dhm_read_public( &dhm, buf, dhm.len ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_dhm_read_public returned %d\n\n", ret );
goto exit;
}
/*
* 7. Derive the shared secret: K = Ys ^ Xc mod P
*/
mbedtls_printf( "\n . Shared secret: " );
fflush( stdout );
if( ( ret = mbedtls_dhm_calc_secret( &dhm, buf, sizeof( buf ), &n,
mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
{
mbedtls_printf( " failed\n ! mbedtls_dhm_calc_secret returned %d\n\n", ret );
goto exit;
}
for( n = 0; n < 16; n++ )
mbedtls_printf( "%02x", buf[n] );
/*
* 8. Setup the AES-256 encryption key
*
* This is an overly simplified example; best practice is
* to hash the shared secret with a random value to derive
* the keying material for the encryption/decryption keys
* and MACs.
*/
mbedtls_printf( "...\n . Encrypting and sending the ciphertext" );
fflush( stdout );
ret = mbedtls_aes_setkey_enc( &aes, buf, 256 );
if( ret != 0 )
goto exit;
memcpy( buf, PLAINTEXT, 16 );
ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
if( ret != 0 )
goto exit;
if( ( ret = mbedtls_net_send( &client_fd, buf, 16 ) ) != 16 )
{
mbedtls_printf( " failed\n ! mbedtls_net_send returned %d\n\n", ret );
goto exit;
}
mbedtls_printf( "\n\n" );
exit_code = MBEDTLS_EXIT_SUCCESS;
exit:
mbedtls_mpi_free( &N ); mbedtls_mpi_free( &P ); mbedtls_mpi_free( &Q );
mbedtls_mpi_free( &D ); mbedtls_mpi_free( &E );
mbedtls_net_free( &client_fd );
mbedtls_net_free( &listen_fd );
mbedtls_aes_free( &aes );
mbedtls_rsa_free( &rsa );
mbedtls_dhm_free( &dhm );
mbedtls_ctr_drbg_free( &ctr_drbg );
mbedtls_entropy_free( &entropy );
#if defined(_WIN32)
mbedtls_printf( " + Press Enter to exit this program.\n" );
fflush( stdout ); getchar();
#endif
mbedtls_exit( exit_code );
}
#endif /* MBEDTLS_AES_C && MBEDTLS_DHM_C && MBEDTLS_ENTROPY_C &&
MBEDTLS_NET_C && MBEDTLS_RSA_C && MBEDTLS_SHA256_C &&
MBEDTLS_FS_IO && MBEDTLS_CTR_DRBG_C */