Start adding srv support for hello verify request

Dummy fixed content for now.

Also, seems to be a race condition in the way the socket is closed and
reopened, leading to a few "random" failures in compat.sh. A fix is planned
for later.
This commit is contained in:
Manuel Pégourié-Gonnard 2014-07-22 11:45:03 +02:00 committed by Paul Bakker
parent a0e1632b79
commit 2c9ee81f6e
3 changed files with 148 additions and 5 deletions

View File

@ -146,6 +146,7 @@
#define POLARSSL_ERR_SSL_INTERNAL_ERROR -0x6C00 /**< Internal error (eg, unexpected failure in lower-level module) */
#define POLARSSL_ERR_SSL_COUNTER_WRAPPING -0x6B80 /**< A counter would wrap (eg, too many messages exchanged). */
#define POLARSSL_ERR_SSL_WAITING_SERVER_HELLO_RENEGO -0x6B00 /**< Unexpected message at ServerHello in renegotiation. */
#define POLARSSL_ERR_SSL_HELLO_VERIFY_REQUIRED -0x6A80 /**< DTLS client must retry for hello verification */
/*
* Various constants

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@ -452,6 +452,8 @@ void polarssl_strerror( int ret, char *buf, size_t buflen )
snprintf( buf, buflen, "SSL - A counter would wrap (eg, too many messages exchanged)" );
if( use_ret == -(POLARSSL_ERR_SSL_WAITING_SERVER_HELLO_RENEGO) )
snprintf( buf, buflen, "SSL - Unexpected message at ServerHello in renegotiation" );
if( use_ret == -(POLARSSL_ERR_SSL_HELLO_VERIFY_REQUIRED) )
snprintf( buf, buflen, "SSL - DTLS client must retry for hello verification" );
#endif /* POLARSSL_SSL_TLS_C */
#if defined(POLARSSL_X509_USE_C) || defined(POLARSSL_X509_CREATE_C)

View File

@ -1116,6 +1116,34 @@ have_ciphersuite_v2:
}
#endif /* POLARSSL_SSL_SRV_SUPPORT_SSLV2_CLIENT_HELLO */
#if defined(POLARSSL_SSL_PROTO_DTLS)
/*
* Generate cookie for DTLS ClientHello verification
*/
static int ssl_generate_verify_cookie( ssl_context *ssl )
{
unsigned char *cookie = ssl->handshake->verify_cookie;
unsigned char cookie_len;
polarssl_free( cookie );
cookie_len = 16; /* fixed for now */
if( ( cookie = polarssl_malloc( cookie_len ) ) == NULL )
{
SSL_DEBUG_MSG( 1, ( "malloc (%d bytes) failed\n", cookie_len ) );
return( POLARSSL_ERR_SSL_MALLOC_FAILED );
}
/* Dummy, fixed string for now */
memset( cookie, 0x2a, cookie_len );
ssl->handshake->verify_cookie = cookie;
ssl->handshake->verify_cookie_len = cookie_len;
return( 0 );
}
#endif /* POLARSSL_SSL_PROTO_DTLS */
static int ssl_parse_client_hello( ssl_context *ssl )
{
int ret;
@ -1161,6 +1189,7 @@ static int ssl_parse_client_hello( ssl_context *ssl )
* Record layer:
* 0 . 0 message type
* 1 . 2 protocol version
* 3 . 11 DTLS: epoch + record sequence number
* 3 . 4 message length
*/
SSL_DEBUG_MSG( 3, ( "client hello v3, message type: %d",
@ -1190,6 +1219,23 @@ static int ssl_parse_client_hello( ssl_context *ssl )
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
/* For DTLS if this is the initial handshake, remember the client sequence
* number to use it in our next message (RFC 6347 4.2.1) */
#if defined(POLARSSL_SSL_PROTO_DTLS)
if( ssl->transport == SSL_TRANSPORT_DATAGRAM &&
ssl->renegotiation == SSL_INITIAL_HANDSHAKE )
{
/* Epoch should be 0 for initial handshakes */
if( ssl->in_ctr[0] != 0 || ssl->in_ctr[1] != 0 )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
memcpy( ssl->out_ctr + 2, ssl->in_ctr + 2, 6 );
}
#endif /* POLARSSL_SSL_PROTO_DTLS */
msg_len = ( ssl->in_len[0] << 8 ) | ssl->in_len[1];
if( ssl->renegotiation == SSL_INITIAL_HANDSHAKE )
@ -1232,7 +1278,14 @@ static int ssl_parse_client_hello( ssl_context *ssl )
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
// TODO: DTLS: check message_seq
/*
* Copy the client's handshake message_seq on initial handshakes
*/
if( ssl->renegotiation == SSL_INITIAL_HANDSHAKE )
ssl->handshake->msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
// TODO: DTLS: check message_seq on non-initial handshakes?
// (or already done in ssl_read_record?)
/*
* For now we don't support fragmentation, so make sure
@ -1376,8 +1429,7 @@ static int ssl_parse_client_hello( ssl_context *ssl )
cookie_offset = 39 + sess_len;
cookie_len = buf[cookie_offset];
if( // cookie_len > <MAX> || // TODO-DTLS
cookie_offset + 1 + cookie_len + 2 > msg_len )
if( cookie_offset + 1 + cookie_len + 2 > msg_len )
{
SSL_DEBUG_MSG( 1, ( "bad client hello message" ) );
return( POLARSSL_ERR_SSL_BAD_HS_CLIENT_HELLO );
@ -1386,9 +1438,34 @@ static int ssl_parse_client_hello( ssl_context *ssl )
SSL_DEBUG_BUF( 3, "client hello, cookie",
buf + cookie_offset + 1, cookie_len );
// TODO-DTLS: check cookie, reject if invalid!
/*
* Generate reference cookie content:
* - used for verification below,
* - stored to be sent if verification fails
*/
if( ( ret = ssl_generate_verify_cookie( ssl ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ssl_generate_verify_cookie", ret );
return( ret );
}
/* If the received cookie is OK, no need to send one */
if( cookie_len == ssl->handshake->verify_cookie_len &&
safer_memcmp( buf + cookie_offset + 1,
ssl->handshake->verify_cookie,
ssl->handshake->verify_cookie_len ) == 0 )
{
polarssl_free( ssl->handshake->verify_cookie );
ssl->handshake->verify_cookie = NULL;
ssl->handshake->verify_cookie_len = 0;
}
SSL_DEBUG_MSG( 2, ( "client hello, cookie verification %s",
ssl->handshake->verify_cookie == NULL ?
"passed" : "failed" ) );
}
#endif
#endif /* POLARSSL_SSL_PROTO_DTLS */
/*
* Check the ciphersuitelist length (will be parsed later)
@ -1883,6 +1960,52 @@ static void ssl_write_alpn_ext( ssl_context *ssl,
}
#endif /* POLARSSL_ECDH_C || POLARSSL_ECDSA_C */
#if defined(POLARSSL_SSL_PROTO_DTLS)
static int ssl_write_hello_verify_request( ssl_context *ssl )
{
int ret;
unsigned char *p = ssl->out_msg + 4;
SSL_DEBUG_MSG( 2, ( "=> write hello verify request" ) );
/*
* struct {
* ProtocolVersion server_version;
* opaque cookie<0..2^8-1>;
* } HelloVerifyRequest;
*/
/* For now, use fixed version = DTLS 1.0 */
ssl_write_version( SSL_MAJOR_VERSION_3, SSL_MINOR_VERSION_1,
ssl->transport, p );
SSL_DEBUG_BUF( 3, "server version", (unsigned char *) p, 2 );
p += 2;
SSL_DEBUG_BUF( 3, "cookie", ssl->handshake->verify_cookie,
ssl->handshake->verify_cookie_len );
*p++ = ssl->handshake->verify_cookie_len;
memcpy( p, ssl->handshake->verify_cookie,
ssl->handshake->verify_cookie_len );
p += ssl->handshake->verify_cookie_len;
ssl->out_msglen = p - ssl->out_msg;
ssl->out_msgtype = SSL_MSG_HANDSHAKE;
ssl->out_msg[0] = SSL_HS_HELLO_VERIFY_REQUEST;
ssl->state = SSL_CLIENT_HELLO;
if( ( ret = ssl_write_record( ssl ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ssl_write_record", ret );
return( ret );
}
SSL_DEBUG_MSG( 2, ( "<= write hello verify request" ) );
return( 0 );
}
#endif /* POLARSSL_SSL_PROTO_DTLS */
static int ssl_write_server_hello( ssl_context *ssl )
{
#if defined(POLARSSL_HAVE_TIME)
@ -1894,6 +2017,23 @@ static int ssl_write_server_hello( ssl_context *ssl )
SSL_DEBUG_MSG( 2, ( "=> write server hello" ) );
#if defined(POLARSSL_SSL_PROTO_DTLS)
if( ssl->transport == SSL_TRANSPORT_DATAGRAM &&
ssl->handshake->verify_cookie != NULL )
{
SSL_DEBUG_MSG( 2, ( "client hello was not authenticated" ) );
SSL_DEBUG_MSG( 2, ( "<= write server hello" ) );
if( ( ret = ssl_write_hello_verify_request( ssl ) ) != 0 )
{
SSL_DEBUG_RET( 1, "ssl_write_hello_verify_request", ret );
return( ret );
}
return( POLARSSL_ERR_SSL_HELLO_VERIFY_REQUIRED );
}
#endif /* POLARSSL_SSL_PROTO_DTLS */
if( ssl->f_rng == NULL )
{
SSL_DEBUG_MSG( 1, ( "no RNG provided") );