Encrypt session tickets
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 1178309..cbec795 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -161,36 +161,56 @@
*/
static int ssl_write_ticket( ssl_context *ssl, size_t *tlen )
{
+ int ret;
unsigned char * const start = ssl->out_msg + 10;
unsigned char *p = start;
- size_t clear_len, enc_len;
+ unsigned char *state;
+ unsigned char iv[16];
+ size_t clear_len, enc_len, pad_len, i;
if( ssl->ticket_keys == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+ /* Write key name */
memcpy( p, ssl->ticket_keys->key_name, 16 );
p += 16;
- memset( p, 0, 16 ); // TODO: iv
+ /* Generate and write IV (with a copy for aes_crypt) */
+ if( ( ret = ssl->f_rng( ssl->p_rng, p, 16 ) ) != 0 )
+ return( ret );
+ memcpy( iv, p, 16 );
p += 16;
- ssl_save_session( ssl->session_negotiate, p + 2, &clear_len );
- SSL_DEBUG_BUF( 4, "session ticket cleartext", p, clear_len );
+ /* Dump session state */
+ state = p + 2;
+ ssl_save_session( ssl->session_negotiate, state, &clear_len );
+ SSL_DEBUG_BUF( 3, "session ticket cleartext", state, clear_len );
- // TODO: encrypt ticket
- enc_len = clear_len;
- (void) enc_len;
+ /* Apply PKCS padding */
+ pad_len = 16 - clear_len % 16;
+ enc_len = clear_len + pad_len;
+ for( i = clear_len; i < enc_len; i++ )
+ state[i] = (unsigned char) pad_len;
- *p++ = (unsigned char)( ( clear_len >> 8 ) & 0xFF );
- *p++ = (unsigned char)( ( clear_len ) & 0xFF );
- p += clear_len;
+ /* Encrypt */
+ if( ( ret = aes_crypt_cbc( &ssl->ticket_keys->enc, AES_ENCRYPT,
+ enc_len, iv, state, state ) ) != 0 )
+ {
+ return( ret );
+ }
- memset( p, 0, 32 ); // TODO: mac
+ /* Write length */
+ *p++ = (unsigned char)( ( enc_len >> 8 ) & 0xFF );
+ *p++ = (unsigned char)( ( enc_len ) & 0xFF );
+ p = state + enc_len;
+
+ /* Compute and write MAC */
+ memset( p, 0, 32 );
p += 32;
*tlen = p - start;
- SSL_DEBUG_BUF( 4, "final session ticket", start, *tlen );
+ SSL_DEBUG_BUF( 3, "session ticket structure", start, *tlen );
return( 0 );
}
@@ -199,17 +219,20 @@
* Load session ticket (see ssl_write_ticket for structure)
*/
static int ssl_parse_ticket( ssl_context *ssl,
- const unsigned char *buf,
+ unsigned char *buf,
size_t len )
{
int ret;
ssl_session session;
- const unsigned char *key_name = buf;
- const unsigned char *iv = buf + 16;
- const unsigned char *enc_len_p = iv + 16;
- const unsigned char *ticket = enc_len_p + 2;
- const unsigned char *mac;
- size_t enc_len, clear_len;
+ unsigned char *key_name = buf;
+ unsigned char *iv = buf + 16;
+ unsigned char *enc_len_p = iv + 16;
+ unsigned char *ticket = enc_len_p + 2;
+ unsigned char *mac;
+ size_t enc_len, clear_len, i;
+ unsigned char pad_len;
+
+ SSL_DEBUG_BUF( 3, "session ticket structure", buf, len );
if( len < 34 || ssl->ticket_keys == NULL )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
@@ -220,15 +243,35 @@
if( len != enc_len + 66 )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+ /* Check name */
if( memcmp( key_name, ssl->ticket_keys->key_name, 16 ) != 0 )
return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
// TODO: check hmac
(void) mac;
- // TODO: decrypt ticket
- clear_len = enc_len;
+ /* Decrypt */
+ if( ( ret = aes_crypt_cbc( &ssl->ticket_keys->dec, AES_DECRYPT,
+ enc_len, iv, ticket, ticket ) ) != 0 )
+ {
+ return( ret );
+ }
+ /* Check PKCS padding */
+ pad_len = ticket[enc_len - 1];
+
+ ret = 0;
+ for( i = 2; i < pad_len; i++ )
+ if( ticket[enc_len - i] != pad_len )
+ ret = POLARSSL_ERR_SSL_BAD_INPUT_DATA;
+ if( ret != 0 )
+ return( ret );
+
+ clear_len = enc_len - pad_len;
+
+ SSL_DEBUG_BUF( 3, "session ticket cleartext", ticket, clear_len );
+
+ /* Actually load session */
if( ( ret = ssl_load_session( &session, ticket, clear_len ) ) != 0 )
{
SSL_DEBUG_MSG( 1, ( "failed to parse ticket content" ) );
@@ -534,9 +577,11 @@
}
static int ssl_parse_session_ticket_ext( ssl_context *ssl,
- const unsigned char *buf,
+ unsigned char *buf,
size_t len )
{
+ int ret;
+
if( ssl->session_tickets == SSL_SESSION_TICKETS_DISABLED )
return( 0 );
@@ -557,8 +602,11 @@
/*
* Failures are ok: just ignore the ticket and proceed.
*/
- if( ssl_parse_ticket( ssl, buf, len ) != 0 )
+ if( ( ret = ssl_parse_ticket( ssl, buf, len ) ) != 0 )
+ {
+ SSL_DEBUG_RET( 1, "ssl_parse_ticket", ret );
return( 0 );
+ }
SSL_DEBUG_MSG( 3, ( "session successfully restored from ticket" ) );
@@ -2438,7 +2486,11 @@
ssl->out_msg[6] = 0x00;
ssl->out_msg[7] = 0x00;
- ssl_write_ticket( ssl, &tlen );
+ if( ( ret = ssl_write_ticket( ssl, &tlen ) ) != 0 )
+ {
+ SSL_DEBUG_RET( 1, "ssl_write_ticket", ret );
+ tlen = 0;
+ }
ssl->out_msg[8] = (unsigned char)( ( tlen >> 8 ) & 0xFF );
ssl->out_msg[9] = (unsigned char)( ( tlen ) & 0xFF );
