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Add missing ret code checks in PEM module

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Add missing return code checks in the functions pem_des_decrypt(),
pem_3des_decrypt() and pem_aes_decrypt() so that the calling function
pem_read_buffer() is notified of errors reported by the crypto
primitives AES, DES and 3DES.
This commit is contained in:
Andres Amaya Garcia 2017-05-30 17:18:06 +01:00
parent 98864d5c0b
commit f5e753a942
2 changed files with 52 additions and 23 deletions
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9
ChangeLog
View file

@ -1,5 +1,14 @@
mbed TLS ChangeLog (Sorted per branch, date)
= mbed TLS 1.3.x branch released xxxx-xx-xx
Bugfix
* Fix unchecked return codes from AES, DES and 3DES functions in
pem_aes_decrypt(), pem_des_decrypt() and pem_des3_decrypt() respectively.
If a call to one of the functions of the cryptographic primitive modules
failed, the error may not be noticed by the function pem_read_buffer()
causing it to return invalid values. Found by Guido Vranken. #756
= mbed TLS 1.3.19 branch released 2017-03-08
Security

66
library/pem.c
View file

@ -135,45 +135,53 @@ static void pem_pbkdf1( unsigned char *key, size_t keylen,
/*
* Decrypt with DES-CBC, using PBKDF1 for key derivation
*/
static void pem_des_decrypt( unsigned char des_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
static int pem_des_decrypt( unsigned char des_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
{
des_context des_ctx;
unsigned char des_key[8];
int ret;
des_init( &des_ctx );
pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen );
des_setkey_dec( &des_ctx, des_key );
des_crypt_cbc( &des_ctx, DES_DECRYPT, buflen,
des_iv, buf, buf );
if( ( ret = des_setkey_dec( &des_ctx, des_key ) ) != 0 )
goto exit;
ret = des_crypt_cbc( &des_ctx, DES_DECRYPT, buflen, des_iv, buf, buf );
exit:
des_free( &des_ctx );
polarssl_zeroize( des_key, 8 );
return( ret );
}
/*
* Decrypt with 3DES-CBC, using PBKDF1 for key derivation
*/
static void pem_des3_decrypt( unsigned char des3_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
static int pem_des3_decrypt( unsigned char des3_iv[8],
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
{
des3_context des3_ctx;
unsigned char des3_key[24];
int ret;
des3_init( &des3_ctx );
pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen );
des3_set3key_dec( &des3_ctx, des3_key );
des3_crypt_cbc( &des3_ctx, DES_DECRYPT, buflen,
des3_iv, buf, buf );
if( ( ret = des3_set3key_dec( &des3_ctx, des3_key ) ) != 0 )
goto exit;
ret = des3_crypt_cbc( &des3_ctx, DES_DECRYPT, buflen, des3_iv, buf, buf );
exit:
des3_free( &des3_ctx );
polarssl_zeroize( des3_key, 24 );
return( ret );
}
#endif /* POLARSSL_DES_C */
@ -181,23 +189,27 @@ static void pem_des3_decrypt( unsigned char des3_iv[8],
/*
* Decrypt with AES-XXX-CBC, using PBKDF1 for key derivation
*/
static void pem_aes_decrypt( unsigned char aes_iv[16], unsigned int keylen,
unsigned char *buf, size_t buflen,
const unsigned char *pwd, size_t pwdlen )
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 )
{
aes_context aes_ctx;
unsigned char aes_key[32];
int ret;
aes_init( &aes_ctx );
pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen );
aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 );
aes_crypt_cbc( &aes_ctx, AES_DECRYPT, buflen,
aes_iv, buf, buf );
if( ( ret = aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 ) ) != 0 )
goto exit;
ret = aes_crypt_cbc( &aes_ctx, AES_DECRYPT, buflen, aes_iv, buf, buf );
exit:
aes_free( &aes_ctx );
polarssl_zeroize( aes_key, keylen );
return( ret );
}
#endif /* POLARSSL_AES_C */
@ -347,22 +359,30 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
return( POLARSSL_ERR_PEM_PASSWORD_REQUIRED );
}
ret = 0;
#if defined(POLARSSL_DES_C)
if( enc_alg == POLARSSL_CIPHER_DES_EDE3_CBC )
pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
ret = pem_des3_decrypt( pem_iv, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_DES_CBC )
pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
ret = pem_des_decrypt( pem_iv, buf, len, pwd, pwdlen );
#endif /* POLARSSL_DES_C */
#if defined(POLARSSL_AES_C)
if( enc_alg == POLARSSL_CIPHER_AES_128_CBC )
pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
ret = pem_aes_decrypt( pem_iv, 16, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_AES_192_CBC )
pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
ret = pem_aes_decrypt( pem_iv, 24, buf, len, pwd, pwdlen );
else if( enc_alg == POLARSSL_CIPHER_AES_256_CBC )
pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
ret = pem_aes_decrypt( pem_iv, 32, buf, len, pwd, pwdlen );
#endif /* POLARSSL_AES_C */
if( ret != 0 )
{
polarssl_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.