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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include "tls/extensions/s2n_client_renegotiation_info.h"
#include <stdint.h>
#include <sys/param.h>
#include "tls/s2n_tls.h"
#include "utils/s2n_safety.h"
static int s2n_client_renegotiation_send(struct s2n_connection *conn, struct s2n_stuffer *out);
static int s2n_client_renegotiation_recv(struct s2n_connection *conn, struct s2n_stuffer *extension);
static bool s2n_client_renegotiation_should_send(struct s2n_connection *conn);
static int s2n_client_renegotiation_if_missing(struct s2n_connection *conn);
const s2n_extension_type s2n_client_renegotiation_info_extension = {
.iana_value = TLS_EXTENSION_RENEGOTIATION_INFO,
.is_response = false,
.send = s2n_client_renegotiation_send,
.recv = s2n_client_renegotiation_recv,
.should_send = s2n_client_renegotiation_should_send,
.if_missing = s2n_client_renegotiation_if_missing,
};
/**
*= https://tools.ietf.org/rfc/rfc5746#3.5
*# o The client MUST include the "renegotiation_info" extension in the
*# ClientHello
*/
static bool s2n_client_renegotiation_should_send(struct s2n_connection *conn)
{
return conn && s2n_handshake_is_renegotiation(conn);
}
/**
*= https://tools.ietf.org/rfc/rfc5746#3.5
*# o The client MUST include the "renegotiation_info" extension in the
*# ClientHello, containing the saved client_verify_data.
*/
static int s2n_client_renegotiation_send(struct s2n_connection *conn, struct s2n_stuffer *out)
{
POSIX_ENSURE_REF(conn);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.5
*# This text applies if the connection's "secure_renegotiation" flag is
*# set to TRUE (if it is set to FALSE, see Section 4.2).
*/
POSIX_ENSURE(conn->secure_renegotiation, S2N_ERR_NO_RENEGOTIATION);
uint8_t renegotiated_connection_len = conn->handshake.finished_len;
POSIX_ENSURE_GT(renegotiated_connection_len, 0);
POSIX_GUARD(s2n_stuffer_write_uint8(out, renegotiated_connection_len));
POSIX_GUARD(s2n_stuffer_write_bytes(out, conn->handshake.client_finished, renegotiated_connection_len));
return S2N_SUCCESS;
}
/**
*= https://tools.ietf.org/rfc/rfc5746#3.6
*# o The server MUST check if the "renegotiation_info" extension is
*# included in the ClientHello.
*
* Note that this extension must also work for SSLv3:
*= https://tools.ietf.org/rfc/rfc5746#4.5
*# TLS servers that support secure renegotiation and support SSLv3 MUST accept SCSV or the
*# "renegotiation_info" extension and respond as described in this
*# specification even if the offered client version is {0x03, 0x00}.
*/
static int s2n_client_renegotiation_recv_initial(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
/**
*= https://tools.ietf.org/rfc/rfc5746#3.6
*# The server MUST then verify
*# that the length of the "renegotiated_connection" field is zero,
*# and if it is not, MUST abort the handshake.
*/
uint8_t renegotiated_connection_len = 0;
POSIX_GUARD(s2n_stuffer_read_uint8(extension, &renegotiated_connection_len));
POSIX_ENSURE(s2n_stuffer_data_available(extension) == 0, S2N_ERR_NON_EMPTY_RENEGOTIATION_INFO);
POSIX_ENSURE(renegotiated_connection_len == 0, S2N_ERR_NON_EMPTY_RENEGOTIATION_INFO);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.6
*# If the extension is present, set secure_renegotiation flag to TRUE.
*/
conn->secure_renegotiation = 1;
return S2N_SUCCESS;
}
static int s2n_client_renegotiation_recv_renegotiation(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
POSIX_ENSURE_REF(conn);
/* s2n-tls servers do not support renegotiation.
* We add the renegotiation version of this logic only for testing.
*/
POSIX_ENSURE(s2n_in_unit_test(), S2N_ERR_NOT_IN_UNIT_TEST);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.7
*# This text applies if the connection's "secure_renegotiation" flag is
*# set to TRUE (if it is set to FALSE, see Section 4.4).
*/
POSIX_ENSURE(conn->secure_renegotiation, S2N_ERR_NO_RENEGOTIATION);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.7
*# o The server MUST verify that the value of the
*# "renegotiated_connection" field is equal to the saved
*# client_verify_data value; if it is not, the server MUST abort the
*# handshake.
*/
uint8_t verify_data_len = conn->handshake.finished_len;
POSIX_ENSURE_GT(verify_data_len, 0);
uint8_t renegotiated_connection_len = 0;
POSIX_GUARD(s2n_stuffer_read_uint8(extension, &renegotiated_connection_len));
POSIX_ENSURE(verify_data_len == renegotiated_connection_len, S2N_ERR_BAD_MESSAGE);
uint8_t *renegotiated_connection = s2n_stuffer_raw_read(extension, verify_data_len);
POSIX_ENSURE_REF(renegotiated_connection);
POSIX_ENSURE(s2n_constant_time_equals(renegotiated_connection, conn->handshake.client_finished, verify_data_len),
S2N_ERR_BAD_MESSAGE);
return S2N_SUCCESS;
}
static int s2n_client_renegotiation_recv(struct s2n_connection *conn, struct s2n_stuffer *extension)
{
if (s2n_handshake_is_renegotiation(conn)) {
POSIX_GUARD(s2n_client_renegotiation_recv_renegotiation(conn, extension));
} else {
POSIX_GUARD(s2n_client_renegotiation_recv_initial(conn, extension));
}
POSIX_ENSURE(s2n_stuffer_data_available(extension) == 0, S2N_ERR_BAD_MESSAGE);
return S2N_SUCCESS;
}
static int s2n_client_renegotiation_if_missing(struct s2n_connection *conn)
{
POSIX_ENSURE_REF(conn);
if (s2n_handshake_is_renegotiation(conn)) {
/* s2n-tls servers do not support renegotiation.
* We add the renegotiation version of this logic only for testing.
*/
POSIX_ENSURE(s2n_in_unit_test(), S2N_ERR_NOT_IN_UNIT_TEST);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.7
*# This text applies if the connection's "secure_renegotiation" flag is
*# set to TRUE (if it is set to FALSE, see Section 4.4).
*/
POSIX_ENSURE(conn->secure_renegotiation, S2N_ERR_NO_RENEGOTIATION);
/**
*= https://tools.ietf.org/rfc/rfc5746#3.7
*# o The server MUST verify that the "renegotiation_info" extension is
*# present; if it is not, the server MUST abort the handshake.
*/
POSIX_BAIL(S2N_ERR_MISSING_EXTENSION);
} else {
/**
*= https://tools.ietf.org/rfc/rfc5746#3.6
*# o If neither the TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV nor the
*# "renegotiation_info" extension was included, set the
*# secure_renegotiation flag to FALSE. In this case, some servers
*# may want to terminate the handshake instead of continuing
*
* We do not terminate the handshake for compatibility reasons.
* See https://github.com/aws/s2n-tls/issues/3528
*/
conn->secure_renegotiation = false;
return S2N_SUCCESS;
}
}
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