Fixed client certificate handling with TLS 1.2

This commit is contained in:
Paul Bakker 2012-11-23 13:38:07 +01:00
parent e667c98fb1
commit 926af7582a
3 changed files with 201 additions and 47 deletions

View file

@ -192,6 +192,11 @@
#define SSL_SIG_RSA 1
/*
* Client Certificate Types
*/
#define SSL_CERT_TYPE_RSA_SIGN 1
/*
* Message, alert and handshake types
*/
@ -351,6 +356,8 @@ struct _ssl_handshake_params
* Handshake specific crypto variables
*/
int sig_alg; /*!< Signature algorithm */
int cert_type; /*!< Requested cert type */
int verify_sig_alg; /*!< Signature algorithm for verify */
#if defined(POLARSSL_DHM_C)
dhm_context dhm_ctx; /*!< DHM key exchange */
#endif

View file

@ -891,15 +891,19 @@ static int ssl_parse_server_key_exchange( ssl_context *ssl )
static int ssl_parse_certificate_request( ssl_context *ssl )
{
int ret;
unsigned char *buf, *p;
size_t n = 0;
size_t cert_type_len = 0, sig_alg_len = 0, dn_len = 0;
SSL_DEBUG_MSG( 2, ( "=> parse certificate request" ) );
/*
* 0 . 0 handshake type
* 1 . 3 handshake length
* 4 . 5 SSL version
* 6 . 6 cert type count
* 7 .. n-1 cert types
* 4 . 4 cert type count
* 5 .. m-1 cert types
* m .. m+1 sig alg length (TLS 1.2 only)
* m+1 .. n-1 SignatureAndHashAlgorithms (TLS 1.2 only)
* n .. n+1 length of all DNs
* n+2 .. n+3 length of DN 1
* n+4 .. ... Distinguished Name #1
@ -926,6 +930,70 @@ static int ssl_parse_certificate_request( ssl_context *ssl )
SSL_DEBUG_MSG( 3, ( "got %s certificate request",
ssl->client_auth ? "a" : "no" ) );
if( ssl->client_auth == 0 )
goto exit;
// TODO: handshake_failure alert for an anonymous server to request
// client authentication
buf = ssl->in_msg;
// Retrieve cert types
//
cert_type_len = buf[4];
n = cert_type_len;
if( ssl->in_hslen < 6 + n )
{
SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
}
p = buf + 4;
while( cert_type_len > 0 )
{
if( *p == SSL_CERT_TYPE_RSA_SIGN )
{
ssl->handshake->cert_type = SSL_CERT_TYPE_RSA_SIGN;
break;
}
cert_type_len--;
p++;
}
if( ssl->handshake->cert_type == 0 )
{
SSL_DEBUG_MSG( 1, ( "no known cert_type provided" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
}
if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
{
sig_alg_len = ( ( buf[5 + n] << 8 )
| ( buf[6 + n] ) );
p = buf + 7 + n;
n += sig_alg_len;
if( ssl->in_hslen < 6 + n )
{
SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
}
}
dn_len = ( ( buf[7 + n] << 8 )
| ( buf[8 + n] ) );
n += dn_len;
if( ssl->in_hslen != 9 + n )
{
SSL_DEBUG_MSG( 1, ( "bad certificate request message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST );
}
exit:
SSL_DEBUG_MSG( 2, ( "<= parse certificate request" ) );
return( 0 );
@ -1102,25 +1170,6 @@ static int ssl_write_certificate_verify( ssl_context *ssl )
return( 0 );
}
if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
{
// TODO TLS1.2 Should be based on allowed signature algorithm received in
// Certificate Request according to RFC 5246. But OpenSSL only allows
// SHA256 and SHA384. Find out why OpenSSL does this.
//
if( ssl->session_negotiate->ciphersuite == TLS_RSA_WITH_AES_256_GCM_SHA384 ||
ssl->session_negotiate->ciphersuite == TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 )
{
hash_id = SIG_RSA_SHA384;
hashlen = 48;
}
else
{
hash_id = SIG_RSA_SHA256;
hashlen = 32;
}
}
if( ssl->rsa_key == NULL )
{
SSL_DEBUG_MSG( 1, ( "got no private key" ) );
@ -1132,23 +1181,52 @@ static int ssl_write_certificate_verify( ssl_context *ssl )
*/
ssl->handshake->calc_verify( ssl, hash );
if ( ssl->rsa_key )
n = ssl->rsa_key_len ( ssl->rsa_key );
if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
if( ssl->minor_ver != SSL_MINOR_VERSION_3 )
{
// TODO TLS1.2 Should be based on allowed signature algorithm received in
// Certificate Request according to RFC 5246. But OpenSSL only allows
// SHA256 and SHA384. Find out why OpenSSL does this.
//
/*
* digitally-signed struct {
* opaque md5_hash[16];
* opaque sha_hash[20];
* };
*
* md5_hash
* MD5(handshake_messages);
*
* sha_hash
* SHA(handshake_messages);
*/
hashlen = 36;
hash_id = SIG_RSA_RAW;
}
else
{
/*
* digitally-signed struct {
* opaque handshake_messages[handshake_messages_length];
* };
*
* Taking shortcut here. We assume that the server always allows the
* PRF Hash function and has sent it in the allowed signature
* algorithms list received in the Certificate Request message.
*
* Until we encounter a server that does not, we will take this
* shortcut.
*
* Reason: Otherwise we should have running hashes for SHA512 and SHA224
* in order to satisfy 'weird' needs from the server side.
*/
if( ssl->session_negotiate->ciphersuite == TLS_RSA_WITH_AES_256_GCM_SHA384 ||
ssl->session_negotiate->ciphersuite == TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 )
{
hash_id = SIG_RSA_SHA384;
hashlen = 48;
ssl->out_msg[4] = SSL_HASH_SHA384;
ssl->out_msg[5] = SSL_SIG_RSA;
}
else
{
hash_id = SIG_RSA_SHA256;
hashlen = 32;
ssl->out_msg[4] = SSL_HASH_SHA256;
ssl->out_msg[5] = SSL_SIG_RSA;
}
@ -1156,6 +1234,9 @@ static int ssl_write_certificate_verify( ssl_context *ssl )
offset = 2;
}
if ( ssl->rsa_key )
n = ssl->rsa_key_len ( ssl->rsa_key );
ssl->out_msg[4 + offset] = (unsigned char)( n >> 8 );
ssl->out_msg[5 + offset] = (unsigned char)( n );

View file

@ -689,7 +689,7 @@ static int ssl_write_server_hello( ssl_context *ssl )
static int ssl_write_certificate_request( ssl_context *ssl )
{
int ret;
size_t n;
size_t n = 0, dn_size, total_dn_size;
unsigned char *buf, *p;
const x509_cert *crt;
@ -707,7 +707,9 @@ static int ssl_write_certificate_request( ssl_context *ssl )
* 0 . 0 handshake type
* 1 . 3 handshake length
* 4 . 4 cert type count
* 5 .. n-1 cert types
* 5 .. m-1 cert types
* m .. m+1 sig alg length (TLS 1.2 only)
* m+1 .. n-1 SignatureAndHashAlgorithms (TLS 1.2 only)
* n .. n+1 length of all DNs
* n+2 .. n+3 length of DN 1
* n+4 .. ... Distinguished Name #1
@ -720,30 +722,60 @@ static int ssl_write_certificate_request( ssl_context *ssl )
* At the moment, only RSA certificates are supported
*/
*p++ = 1;
*p++ = 1;
*p++ = SSL_CERT_TYPE_RSA_SIGN;
/*
* Add signature_algorithms for verify (TLS 1.2)
* Only add current running algorithm that is already required for
* requested ciphersuite.
*
* Length is always 2
*/
if( ssl->max_minor_ver == SSL_MINOR_VERSION_3 )
{
ssl->handshake->verify_sig_alg = SSL_HASH_SHA256;
*p++ = 0;
*p++ = 2;
if( ssl->session_negotiate->ciphersuite == TLS_RSA_WITH_AES_256_GCM_SHA384 ||
ssl->session_negotiate->ciphersuite == TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 )
{
ssl->handshake->verify_sig_alg = SSL_HASH_SHA384;
}
*p++ = ssl->handshake->verify_sig_alg;
*p++ = SSL_SIG_RSA;
n += 4;
}
p += 2;
crt = ssl->ca_chain;
total_dn_size = 2;
while( crt != NULL )
{
if( p - buf > 4096 )
break;
n = crt->subject_raw.len;
*p++ = (unsigned char)( n >> 8 );
*p++ = (unsigned char)( n );
memcpy( p, crt->subject_raw.p, n );
dn_size = crt->subject_raw.len;
*p++ = (unsigned char)( dn_size >> 8 );
*p++ = (unsigned char)( dn_size );
memcpy( p, crt->subject_raw.p, dn_size );
p += dn_size;
SSL_DEBUG_BUF( 3, "requested DN", p, n );
p += n; crt = crt->next;
SSL_DEBUG_BUF( 3, "requested DN", p, dn_size );
total_dn_size += dn_size;
crt = crt->next;
}
ssl->out_msglen = n = p - buf;
ssl->out_msglen = p - buf;
ssl->out_msgtype = SSL_MSG_HANDSHAKE;
ssl->out_msg[0] = SSL_HS_CERTIFICATE_REQUEST;
ssl->out_msg[6] = (unsigned char)( ( n - 8 ) >> 8 );
ssl->out_msg[7] = (unsigned char)( ( n - 8 ) );
ssl->out_msg[6 + n] = (unsigned char)( total_dn_size >> 8 );
ssl->out_msg[7 + n] = (unsigned char)( total_dn_size );
ret = ssl_write_record( ssl );
@ -1170,8 +1202,10 @@ static int ssl_parse_client_key_exchange( ssl_context *ssl )
static int ssl_parse_certificate_verify( ssl_context *ssl )
{
int ret;
size_t n1, n2;
size_t n = 0, n1, n2;
unsigned char hash[48];
int hash_id;
unsigned int hashlen;
SSL_DEBUG_MSG( 2, ( "=> parse certificate verify" ) );
@ -1204,17 +1238,49 @@ static int ssl_parse_certificate_verify( ssl_context *ssl )
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_VERIFY );
}
n1 = ssl->session_negotiate->peer_cert->rsa.len;
n2 = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
if( ssl->minor_ver == SSL_MINOR_VERSION_3 )
{
/*
* As server we know we either have SSL_HASH_SHA384 or
* SSL_HASH_SHA256
*/
if( ssl->in_msg[4] != ssl->handshake->verify_sig_alg ||
ssl->in_msg[5] != SSL_SIG_RSA )
{
SSL_DEBUG_MSG( 1, ( "peer not adhering to requested sig_alg for verify message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_VERIFY );
}
if( n1 + 6 != ssl->in_hslen || n1 != n2 )
if( ssl->handshake->verify_sig_alg == SSL_HASH_SHA384 )
{
hashlen = 48;
hash_id = SIG_RSA_SHA384;
}
else
{
hashlen = 32;
hash_id = SIG_RSA_SHA256;
}
n += 2;
}
else
{
hashlen = 36;
hash_id = SIG_RSA_RAW;
}
n1 = ssl->session_negotiate->peer_cert->rsa.len;
n2 = ( ssl->in_msg[4 + n] << 8 ) | ssl->in_msg[5 + 2];
if( n + n1 + 6 != ssl->in_hslen || n1 != n2 )
{
SSL_DEBUG_MSG( 1, ( "bad certificate verify message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CERTIFICATE_VERIFY );
}
ret = rsa_pkcs1_verify( &ssl->session_negotiate->peer_cert->rsa, RSA_PUBLIC,
SIG_RSA_RAW, 36, hash, ssl->in_msg + 6 );
hash_id, hashlen, hash, ssl->in_msg + 6 + n );
if( ret != 0 )
{
SSL_DEBUG_RET( 1, "rsa_pkcs1_verify", ret );