Add a timestamp to the cookie
/*
* 2 bytes for packet length, 2 bytes for format version, 2 bytes for
* protocol version, 2 bytes for group id, 2 bytes for cipher id, 1 byte for
- * key_share present flag, 2 bytes for the hashlen, EVP_MAX_MD_SIZE for
- * transcript hash, 1 byte for app cookie length, app cookie length bytes,
- * SHA256_DIGEST_LENGTH bytes for the HMAC of the whole thing.
+ * key_share present flag, 4 bytes for timestamp, 2 bytes for the hashlen,
+ * EVP_MAX_MD_SIZE for transcript hash, 1 byte for app cookie length, app cookie
+ * length bytes, SHA256_DIGEST_LENGTH bytes for the HMAC of the whole thing.
*/
-#define MAX_COOKIE_SIZE (2 + 2 + 2 + 2 + 2 + 1 + 2 + EVP_MAX_MD_SIZE + 1 \
+#define MAX_COOKIE_SIZE (2 + 2 + 2 + 2 + 2 + 1 + 4 + 2 + EVP_MAX_MD_SIZE + 1 \
+ SSL_COOKIE_LENGTH + SHA256_DIGEST_LENGTH)
/*
@@ -705,6 +705,7 @@ int tls_parse_ctos_cookie(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
unsigned char hmac[SHA256_DIGEST_LENGTH];
unsigned char hrr[MAX_HRR_SIZE];
size_t rawlen, hmaclen, hrrlen, ciphlen;
+ unsigned long tm, now;
/* Ignore any cookie if we're not set up to verify it */
if (s->ctx->app_verify_cookie_cb == NULL
@@ -814,6 +815,7 @@ int tls_parse_ctos_cookie(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
}
if (!PACKET_get_1(&cookie, &key_share)
+ || !PACKET_get_net_4(&cookie, &tm)
|| !PACKET_get_length_prefixed_2(&cookie, &chhash)
|| !PACKET_get_length_prefixed_1(&cookie, &appcookie)
|| PACKET_remaining(&cookie) != SHA256_DIGEST_LENGTH) {
@@ -822,6 +824,13 @@ int tls_parse_ctos_cookie(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
return 0;
}
+ /* We tolerate a cookie age of up to 10 minutes (= 60 * 10 seconds) */
+ now = (unsigned long)time(NULL);
+ if (tm > now || (now - tm) > 600) {
+ /* Cookie is stale. Ignore it */
+ return 1;
+ }
+
/* Verify the app cookie */
if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&appcookie),
PACKET_remaining(&appcookie)) == 0) {
@@ -1603,6 +1612,7 @@ EXT_RETURN tls_construct_stoc_cookie(SSL *s, WPACKET *pkt, unsigned int context,
&ciphlen)
/* Is there a key_share extension present in this HRR? */
|| !WPACKET_put_bytes_u8(pkt, s->s3->peer_tmp == NULL)
+ || !WPACKET_put_bytes_u32(pkt, (unsigned int)time(NULL))
|| !WPACKET_start_sub_packet_u16(pkt)
|| !WPACKET_reserve_bytes(pkt, EVP_MAX_MD_SIZE, &hashval1)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_STOC_COOKIE,
