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/*
* Copyright (C) 2017 Red Hat, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>
*
*/
#include "gnutls_int.h"
#include "errors.h"
#include "handshake.h"
#include "tls13/key_update.h"
#include "mem.h"
#include "mbuffers.h"
#include "secrets.h"
#define KEY_UPDATES_WINDOW 1000
#define KEY_UPDATES_PER_WINDOW 8
static int update_keys(gnutls_session_t session, hs_stage_t stage)
{
int ret;
ret = _tls13_update_secret(session, session->key.proto.tls13.temp_secret,
session->key.proto.tls13.temp_secret_size);
if (ret < 0)
return gnutls_assert_val(ret);
_gnutls_epoch_bump(session);
ret = _gnutls_epoch_dup(session, EPOCH_READ_CURRENT);
if (ret < 0)
return gnutls_assert_val(ret);
/* If we send a key update during early start, only update our
* write keys */
if (session->internals.recv_state == RECV_STATE_EARLY_START) {
ret = _tls13_write_connection_state_init(session, stage);
} else {
ret = _tls13_connection_state_init(session, stage);
}
if (ret < 0)
return gnutls_assert_val(ret);
return 0;
}
int _gnutls13_recv_key_update(gnutls_session_t session, gnutls_buffer_st *buf)
{
int ret;
struct timespec now;
if (buf->length != 1)
return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
gnutls_gettime(&now);
/* Roll over the counter if the time window has elapsed */
if (session->internals.key_update_count == 0 ||
timespec_sub_ms(&now, &session->internals.last_key_update) >
KEY_UPDATES_WINDOW) {
session->internals.last_key_update = now;
session->internals.key_update_count = 0;
}
if (unlikely(++session->internals.key_update_count >
KEY_UPDATES_PER_WINDOW)) {
_gnutls_debug_log("reached maximum number of key updates per %d milliseconds (%d)\n",
KEY_UPDATES_WINDOW,
KEY_UPDATES_PER_WINDOW);
return gnutls_assert_val(GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETS);
}
_gnutls_epoch_gc(session);
_gnutls_handshake_log("HSK[%p]: received TLS 1.3 key update (%u)\n",
session, (unsigned)buf->data[0]);
switch(buf->data[0]) {
case 0:
/* peer updated its key, not requested our key update */
ret = update_keys(session, STAGE_UPD_PEERS);
if (ret < 0)
return gnutls_assert_val(ret);
break;
case 1:
if (session->internals.hsk_flags & HSK_KEY_UPDATE_ASKED) {
/* if we had asked a key update we shouldn't get this
* reply */
return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);
}
/* peer updated its key, requested our key update */
ret = update_keys(session, STAGE_UPD_PEERS);
if (ret < 0)
return gnutls_assert_val(ret);
/* we mark that a key update is schedule, and it
* will be performed prior to sending the next application
* message.
*/
if (session->internals.rsend_state == RECORD_SEND_NORMAL)
session->internals.rsend_state = RECORD_SEND_KEY_UPDATE_1;
else if (session->internals.rsend_state == RECORD_SEND_CORKED)
session->internals.rsend_state = RECORD_SEND_CORKED_TO_KU;
break;
default:
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
}
session->internals.hsk_flags &= ~(unsigned)(HSK_KEY_UPDATE_ASKED);
return 0;
}
int _gnutls13_send_key_update(gnutls_session_t session, unsigned again, unsigned flags /* GNUTLS_KU_* */)
{
int ret;
mbuffer_st *bufel = NULL;
uint8_t val;
if (again == 0) {
if (flags & GNUTLS_KU_PEER) {
/* mark that we asked a key update to prevent an
* infinite ping pong when receiving the reply */
session->internals.hsk_flags |= HSK_KEY_UPDATE_ASKED;
val = 0x01;
} else {
val = 0x00;
}
_gnutls_handshake_log("HSK[%p]: sending key update (%u)\n", session, (unsigned)val);
bufel = _gnutls_handshake_alloc(session, 1);
if (bufel == NULL)
return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
_mbuffer_set_udata_size(bufel, 0);
ret = _mbuffer_append_data(bufel, &val, 1);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
}
return _gnutls_send_handshake(session, bufel, GNUTLS_HANDSHAKE_KEY_UPDATE);
cleanup:
_mbuffer_xfree(&bufel);
return ret;
}
/**
* gnutls_session_key_update:
* @session: is a #gnutls_session_t type.
* @flags: zero of %GNUTLS_KU_PEER
*
* This function will update/refresh the session keys when the
* TLS protocol is 1.3 or better. The peer is notified of the
* update by sending a message, so this function should be
* treated similarly to gnutls_record_send() --i.e., it may
* return %GNUTLS_E_AGAIN or %GNUTLS_E_INTERRUPTED.
*
* When this flag %GNUTLS_KU_PEER is specified, this function
* in addition to updating the local keys, will ask the peer to
* refresh its keys too.
*
* If the negotiated version is not TLS 1.3 or better this
* function will return %GNUTLS_E_INVALID_REQUEST.
*
* Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
*
* Since: 3.6.3
**/
int gnutls_session_key_update(gnutls_session_t session, unsigned flags)
{
int ret;
const version_entry_st *vers = get_version(session);
if (!vers->tls13_sem)
return GNUTLS_E_INVALID_REQUEST;
ret =
_gnutls13_send_key_update(session, AGAIN(STATE150), flags);
STATE = STATE150;
if (ret < 0) {
gnutls_assert();
return ret;
}
STATE = STATE0;
_gnutls_epoch_gc(session);
/* it was completely sent, update the keys */
ret = update_keys(session, STAGE_UPD_OURS);
if (ret < 0)
return gnutls_assert_val(ret);
return 0;
}
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