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Don't pass zero to rsa_complete() as a param

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When parsing a PKCS#1 RSAPrivateKey structure, all parameters are always
present. After importing them, we need to call rsa_complete() for the sake of
alternative implementations. That function interprets zero as a signal for
"this parameter was not provided". As that's never the case, we mustn't pass
any zero value to that function, so we need to explicitly check for it.
This commit is contained in:
Manuel Pégourié-Gonnard 2020-02-18 10:12:14 +01:00
parent 4d8c836cdc
commit a04a2c3ef1
1 changed files with 50 additions and 31 deletions
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81
library/pkparse.c
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@ -678,6 +678,32 @@ int mbedtls_pk_parse_subpubkey( unsigned char **p, const unsigned char *end,
}
#if defined(MBEDTLS_RSA_C)
/*
* Wrapper around mbedtls_asn1_get_mpi() that rejects zero.
*
* The value zero is:
* - never a valid value for an RSA parameter
* - interpreted as "omitted, please reconstruct" by mbedtls_rsa_complete().
*
* Since values can't be omitted in PKCS#1, passing a zero value to
* rsa_complete() would be incorrect, so reject zero values early.
*/
static int asn1_get_nonzero_mpi( unsigned char **p,
const unsigned char *end,
mbedtls_mpi *X )
{
int ret;
ret = mbedtls_asn1_get_mpi( p, end, X );
if( ret != 0 )
return( ret );
if( mbedtls_mpi_cmp_int( X, 0 ) == 0 )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT );
return( 0 );
}
/*
* Parse a PKCS#1 encoded private RSA key
*/
@ -730,44 +756,34 @@ static int pk_parse_key_pkcs1_der( mbedtls_rsa_context *rsa,
}
/* Import N */
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ||
( ret = mbedtls_rsa_import_raw( rsa, p, len, NULL, 0, NULL, 0,
NULL, 0, NULL, 0 ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_rsa_import( rsa, &T, NULL, NULL,
NULL, NULL ) ) != 0 )
goto cleanup;
p += len;
/* Import E */
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ||
( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, NULL, 0,
NULL, 0, p, len ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_rsa_import( rsa, NULL, NULL, NULL,
NULL, &T ) ) != 0 )
goto cleanup;
p += len;
/* Import D */
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ||
( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, NULL, 0,
p, len, NULL, 0 ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_rsa_import( rsa, NULL, NULL, NULL,
&T, NULL ) ) != 0 )
goto cleanup;
p += len;
/* Import P */
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ||
( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, p, len, NULL, 0,
NULL, 0, NULL, 0 ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_rsa_import( rsa, NULL, &T, NULL,
NULL, NULL ) ) != 0 )
goto cleanup;
p += len;
/* Import Q */
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ||
( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, p, len,
NULL, 0, NULL, 0 ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_rsa_import( rsa, NULL, NULL, &T,
NULL, NULL ) ) != 0 )
goto cleanup;
p += len;
#if !defined(MBEDTLS_RSA_NO_CRT)
/*
@ -782,22 +798,25 @@ static int pk_parse_key_pkcs1_der( mbedtls_rsa_context *rsa,
*/
/* Import DP */
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->DP ) ) != 0)
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_mpi_copy( &rsa->DP, &T ) ) != 0 )
goto cleanup;
/* Import DQ */
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->DQ ) ) != 0)
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_mpi_copy( &rsa->DQ, &T ) ) != 0 )
goto cleanup;
/* Import QP */
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->QP ) ) != 0)
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_mpi_copy( &rsa->QP, &T ) ) != 0 )
goto cleanup;
#else
/* Verify existance of the CRT params */
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 ||
( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 )
if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ||
( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 )
goto cleanup;
#endif