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mbedtls/library/pem.c
Janos Follath 24eed8d2d2 Initialise return values to an error 
Initialising the return values to and error is best practice and makes
the library more robust.
2019-12-03 16:07:18 +00:00

492 lines
14 KiB
C
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/*
* Privacy Enhanced Mail (PEM) decoding
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* 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.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#include "mbedtls/base64.h"
#include "mbedtls/des.h"
#include "mbedtls/aes.h"
#include "mbedtls/md5.h"
#include "mbedtls/cipher.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include <string.h>
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#if defined(MBEDTLS_PEM_PARSE_C)
void mbedtls_pem_init( mbedtls_pem_context *ctx )
{
memset( ctx, 0, sizeof( mbedtls_pem_context ) );
}
#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
/*
* Read a 16-byte hex string and convert it to binary
*/
static int pem_get_iv( const unsigned char *s, unsigned char *iv,
size_t iv_len )
{
size_t i, j, k;
memset( iv, 0, iv_len );
for( i = 0; i < iv_len * 2; i++, s++ )
{
if( *s >= '0' && *s <= '9' ) j = *s - '0'; else
if( *s >= 'A' && *s <= 'F' ) j = *s - '7'; else
if( *s >= 'a' && *s <= 'f' ) j = *s - 'W'; else
return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
k = ( ( i & 1 ) != 0 ) ? j : j << 4;
iv[i >> 1] = (unsigned char)( iv[i >> 1] | k );
}
return( 0 );
}
static int pem_pbkdf1( unsigned char *key, size_t keylen,
unsigned char *iv,
const unsigned char *pwd, size_t pwdlen )
{
mbedtls_md5_context md5_ctx;
unsigned char md5sum[16];
size_t use_len;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_md5_init( &md5_ctx );
/*
* key[ 0..15] = MD5(pwd || IV)
*/
if( ( ret = mbedtls_md5_starts_ret( &md5_ctx ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_update_ret( &md5_ctx, pwd, pwdlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_update_ret( &md5_ctx, iv, 8 ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_finish_ret( &md5_ctx, md5sum ) ) != 0 )
goto exit;
if( keylen <= 16 )
{
memcpy( key, md5sum, keylen );
goto exit;
}
memcpy( key, md5sum, 16 );
/*
* key[16..23] = MD5(key[ 0..15] || pwd || IV])
*/
if( ( ret = mbedtls_md5_starts_ret( &md5_ctx ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_update_ret( &md5_ctx, md5sum, 16 ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_update_ret( &md5_ctx, pwd, pwdlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_update_ret( &md5_ctx, iv, 8 ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md5_finish_ret( &md5_ctx, md5sum ) ) != 0 )
goto exit;
use_len = 16;
if( keylen < 32 )
use_len = keylen - 16;
memcpy( key + 16, md5sum, use_len );
exit:
mbedtls_md5_free( &md5_ctx );
mbedtls_platform_zeroize( md5sum, 16 );
return( ret );
}
#if defined(MBEDTLS_DES_C)
/*
* Decrypt with DES-CBC, using PBKDF1 for key derivation
*/
static int pem_des_decrypt( unsigned char des_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
{
mbedtls_des_context des_ctx;
unsigned char des_key[8];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_des_init( &des_ctx );
if( ( ret = pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_des_setkey_dec( &des_ctx, des_key ) ) != 0 )
goto exit;
ret = mbedtls_des_crypt_cbc( &des_ctx, MBEDTLS_DES_DECRYPT, buflen,
des_iv, buf, buf );
exit:
mbedtls_des_free( &des_ctx );
mbedtls_platform_zeroize( des_key, 8 );
return( ret );
}
/*
* Decrypt with 3DES-CBC, using PBKDF1 for key derivation
*/
static int pem_des3_decrypt( unsigned char des3_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
{
mbedtls_des3_context des3_ctx;
unsigned char des3_key[24];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_des3_init( &des3_ctx );
if( ( ret = pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_des3_set3key_dec( &des3_ctx, des3_key ) ) != 0 )
goto exit;
ret = mbedtls_des3_crypt_cbc( &des3_ctx, MBEDTLS_DES_DECRYPT, buflen,
des3_iv, buf, buf );
exit:
mbedtls_des3_free( &des3_ctx );
mbedtls_platform_zeroize( des3_key, 24 );
return( ret );
}
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
/*
* Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
*/
static int pem_aes_decrypt( unsigned char aes_iv[16], unsigned int keylen,
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
{
mbedtls_aes_context aes_ctx;
unsigned char aes_key[32];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_aes_init( &aes_ctx );
if( ( ret = pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 ) ) != 0 )
goto exit;
ret = mbedtls_aes_crypt_cbc( &aes_ctx, MBEDTLS_AES_DECRYPT, buflen,
aes_iv, buf, buf );
exit:
mbedtls_aes_free( &aes_ctx );
mbedtls_platform_zeroize( aes_key, keylen );
return( ret );
}
#endif /* MBEDTLS_AES_C */
#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const char *footer,
const unsigned char *data, const unsigned char *pwd,
size_t pwdlen, size_t *use_len )
{
int ret, enc;
size_t len;
unsigned char *buf;
const unsigned char *s1, *s2, *end;
#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
unsigned char pem_iv[16];
mbedtls_cipher_type_t enc_alg = MBEDTLS_CIPHER_NONE;
#else
((void) pwd);
((void) pwdlen);
#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
if( ctx == NULL )
return( MBEDTLS_ERR_PEM_BAD_INPUT_DATA );
s1 = (unsigned char *) strstr( (const char *) data, header );
if( s1 == NULL )
return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
s2 = (unsigned char *) strstr( (const char *) data, footer );
if( s2 == NULL || s2 <= s1 )
return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
s1 += strlen( header );
if( *s1 == ' ' ) s1++;
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT );
end = s2;
end += strlen( footer );
if( *end == ' ' ) end++;
if( *end == '\r' ) end++;
if( *end == '\n' ) end++;
*use_len = end - data;
enc = 0;
if( s2 - s1 >= 22 && memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
{
#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
enc++;
s1 += 22;
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( MBEDTLS_ERR_PEM_INVALID_DATA );
#if defined(MBEDTLS_DES_C)
if( s2 - s1 >= 23 && memcmp( s1, "DEK-Info: DES-EDE3-CBC,", 23 ) == 0 )
{
enc_alg = MBEDTLS_CIPHER_DES_EDE3_CBC;
s1 += 23;
if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8 ) != 0 )
return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
}
else if( s2 - s1 >= 18 && memcmp( s1, "DEK-Info: DES-CBC,", 18 ) == 0 )
{
enc_alg = MBEDTLS_CIPHER_DES_CBC;
s1 += 18;
if( s2 - s1 < 16 || pem_get_iv( s1, pem_iv, 8) != 0 )
return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
s1 += 16;
}
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
if( s2 - s1 >= 14 && memcmp( s1, "DEK-Info: AES-", 14 ) == 0 )
{
if( s2 - s1 < 22 )
return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );
else if( memcmp( s1, "DEK-Info: AES-128-CBC,", 22 ) == 0 )
enc_alg = MBEDTLS_CIPHER_AES_128_CBC;
else if( memcmp( s1, "DEK-Info: AES-192-CBC,", 22 ) == 0 )
enc_alg = MBEDTLS_CIPHER_AES_192_CBC;
else if( memcmp( s1, "DEK-Info: AES-256-CBC,", 22 ) == 0 )
enc_alg = MBEDTLS_CIPHER_AES_256_CBC;
else
return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );
s1 += 22;
if( s2 - s1 < 32 || pem_get_iv( s1, pem_iv, 16 ) != 0 )
return( MBEDTLS_ERR_PEM_INVALID_ENC_IV );
s1 += 32;
}
#endif /* MBEDTLS_AES_C */
if( enc_alg == MBEDTLS_CIPHER_NONE )
return( MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG );
if( *s1 == '\r' ) s1++;
if( *s1 == '\n' ) s1++;
else return( MBEDTLS_ERR_PEM_INVALID_DATA );
#else
return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
}
if( s1 >= s2 )
return( MBEDTLS_ERR_PEM_INVALID_DATA );
ret = mbedtls_base64_decode( NULL, 0, &len, s1, s2 - s1 );
if( ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER )
return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
if( ( buf = mbedtls_calloc( 1, len ) ) == NULL )
return( MBEDTLS_ERR_PEM_ALLOC_FAILED );
if( ( ret = mbedtls_base64_decode( buf, len, &len, s1, s2 - s1 ) ) != 0 )
{
mbedtls_platform_zeroize( buf, len );
mbedtls_free( buf );
return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
}
if( enc != 0 )
{
#if defined(MBEDTLS_MD5_C) && defined(MBEDTLS_CIPHER_MODE_CBC) && \
( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
if( pwd == NULL )
{
mbedtls_platform_zeroize( buf, len );
mbedtls_free( buf );
return( MBEDTLS_ERR_PEM_PASSWORD_REQUIRED );
}
ret = 0;
#if defined(MBEDTLS_DES_C)
if( enc_alg == MBEDTLS_CIPHER_DES_EDE3_CBC )
ret = pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
else if( enc_alg == MBEDTLS_CIPHER_DES_CBC )
ret = pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
#endif /* MBEDTLS_DES_C */
#if defined(MBEDTLS_AES_C)
if( enc_alg == MBEDTLS_CIPHER_AES_128_CBC )
ret = pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
else if( enc_alg == MBEDTLS_CIPHER_AES_192_CBC )
ret = pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
else if( enc_alg == MBEDTLS_CIPHER_AES_256_CBC )
ret = pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
#endif /* MBEDTLS_AES_C */
if( ret != 0 )
{
mbedtls_free( buf );
return( ret );
}
/*
* The result will be ASN.1 starting with a SEQUENCE tag, with 1 to 3
* length bytes (allow 4 to be sure) in all known use cases.
*
* Use that as a heuristic to try to detect password mismatches.
*/
if( len <= 2 || buf[0] != 0x30 || buf[1] > 0x83 )
{
mbedtls_platform_zeroize( buf, len );
mbedtls_free( buf );
return( MBEDTLS_ERR_PEM_PASSWORD_MISMATCH );
}
#else
mbedtls_platform_zeroize( buf, len );
mbedtls_free( buf );
return( MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE );
#endif /* MBEDTLS_MD5_C && MBEDTLS_CIPHER_MODE_CBC &&
( MBEDTLS_AES_C || MBEDTLS_DES_C ) */
}
ctx->buf = buf;
ctx->buflen = len;
return( 0 );
}
void mbedtls_pem_free( mbedtls_pem_context *ctx )
{
if ( ctx->buf != NULL )
{
mbedtls_platform_zeroize( ctx->buf, ctx->buflen );
mbedtls_free( ctx->buf );
}
mbedtls_free( ctx->info );
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_pem_context ) );
}
#endif /* MBEDTLS_PEM_PARSE_C */
#if defined(MBEDTLS_PEM_WRITE_C)
int mbedtls_pem_write_buffer( const char *header, const char *footer,
const unsigned char *der_data, size_t der_len,
unsigned char *buf, size_t buf_len, size_t *olen )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *encode_buf = NULL, *c, *p = buf;
size_t len = 0, use_len, add_len = 0;
mbedtls_base64_encode( NULL, 0, &use_len, der_data, der_len );
add_len = strlen( header ) + strlen( footer ) + ( use_len / 64 ) + 1;
if( use_len + add_len > buf_len )
{
*olen = use_len + add_len;
return( MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL );
}
if( use_len != 0 &&
( ( encode_buf = mbedtls_calloc( 1, use_len ) ) == NULL ) )
return( MBEDTLS_ERR_PEM_ALLOC_FAILED );
if( ( ret = mbedtls_base64_encode( encode_buf, use_len, &use_len, der_data,
der_len ) ) != 0 )
{
mbedtls_free( encode_buf );
return( ret );
}
memcpy( p, header, strlen( header ) );
p += strlen( header );
c = encode_buf;
while( use_len )
{
len = ( use_len > 64 ) ? 64 : use_len;
memcpy( p, c, len );
use_len -= len;
p += len;
c += len;
*p++ = '\n';
}
memcpy( p, footer, strlen( footer ) );
p += strlen( footer );
*p++ = '\0';
*olen = p - buf;
mbedtls_free( encode_buf );
return( 0 );
}
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */
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