Merge pull request #8857 from ronald-cron-arm/tls13-cli-max-early-data-size
TLS 1.3: Enforce max_early_data_size on client
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 0c71157..4949306 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -6074,7 +6074,7 @@
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const struct mbedtls_ssl_config *conf;
- int written_data_len = 0;
+ uint32_t remaining;
MBEDTLS_SSL_DEBUG_MSG(2, ("=> write early_data"));
@@ -6124,18 +6124,27 @@
return ret;
}
}
+ remaining = ssl->session_negotiate->max_early_data_size;
} else {
/*
- * If we are past the point where we can send early data, return
- * immediatly. Otherwise, progress the handshake as much as possible to
- * not delay it too much. If we reach a point where we can still send
- * early data, then we will send some.
+ * If we are past the point where we can send early data or we have
+ * already reached the maximum early data size, return immediatly.
+ * Otherwise, progress the handshake as much as possible to not delay
+ * it too much. If we reach a point where we can still send early data,
+ * then we will send some.
*/
if ((ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_CAN_WRITE) &&
(ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED)) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
+ remaining = ssl->session_negotiate->max_early_data_size -
+ ssl->total_early_data_size;
+
+ if (remaining == 0) {
+ return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
+ }
+
ret = mbedtls_ssl_handshake(ssl);
if ((ret != 0) && (ret != MBEDTLS_ERR_SSL_WANT_READ)) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret);
@@ -6143,16 +6152,24 @@
}
}
- if ((ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_CAN_WRITE) &&
- (ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED)) {
+ if (((ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_CAN_WRITE) &&
+ (ssl->early_data_status != MBEDTLS_SSL_EARLY_DATA_STATUS_ACCEPTED))
+ || (remaining == 0)) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
- written_data_len = ssl_write_real(ssl, buf, len);
+ if (len > remaining) {
+ len = remaining;
+ }
- MBEDTLS_SSL_DEBUG_MSG(2, ("<= write early_data, len=%d", written_data_len));
+ ret = ssl_write_real(ssl, buf, len);
+ if (ret >= 0) {
+ ssl->total_early_data_size += ret;
+ }
- return written_data_len;
+ MBEDTLS_SSL_DEBUG_MSG(2, ("<= write early_data, ret=%d", ret));
+
+ return ret;
}
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_CLI_C */
diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index c0c816c..e95aada 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -3310,6 +3310,18 @@
TLS 1.3 write early data, hello retry request
tls13_write_early_data:TEST_EARLY_DATA_HRR
+TLS 1.3 cli, maximum early data size, default size
+tls13_cli_max_early_data_size:-1
+
+TLS 1.3 cli, maximum early data size, zero
+tls13_cli_max_early_data_size:0
+
+TLS 1.3 cli, maximum early data size, very small but not 0
+tls13_cli_max_early_data_size:3
+
+TLS 1.3 cli, maximum early data size, 93
+tls13_cli_max_early_data_size:93
+
TLS 1.3 srv, max early data size, dflt, wsz=96
tls13_srv_max_early_data_size:TEST_EARLY_DATA_ACCEPTED:-1:96
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 6e95817..0c9ccf1 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -4503,6 +4503,154 @@
}
/* END_CASE */
+/* BEGIN_CASE depends_on:MBEDTLS_SSL_EARLY_DATA:MBEDTLS_SSL_CLI_C:MBEDTLS_SSL_SRV_C:MBEDTLS_DEBUG_C:MBEDTLS_TEST_AT_LEAST_ONE_TLS1_3_CIPHERSUITE:MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED:MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_EPHEMERAL_ENABLED:MBEDTLS_MD_CAN_SHA256:MBEDTLS_ECP_HAVE_SECP256R1:MBEDTLS_ECP_HAVE_SECP384R1:MBEDTLS_PK_CAN_ECDSA_VERIFY:MBEDTLS_SSL_SESSION_TICKETS */
+void tls13_cli_max_early_data_size(int max_early_data_size_arg)
+{
+ int ret = -1;
+ mbedtls_test_ssl_endpoint client_ep, server_ep;
+ mbedtls_test_handshake_test_options client_options;
+ mbedtls_test_handshake_test_options server_options;
+ mbedtls_ssl_session saved_session;
+ unsigned char *buf = NULL;
+ uint32_t buf_size = 64;
+ uint32_t max_early_data_size;
+ uint32_t written_early_data_size = 0;
+ uint32_t read_early_data_size = 0;
+
+ mbedtls_platform_zeroize(&client_ep, sizeof(client_ep));
+ mbedtls_platform_zeroize(&server_ep, sizeof(server_ep));
+ mbedtls_test_init_handshake_options(&client_options);
+ mbedtls_test_init_handshake_options(&server_options);
+ mbedtls_ssl_session_init(&saved_session);
+
+ PSA_INIT();
+ TEST_CALLOC(buf, buf_size);
+
+ /*
+ * Run first handshake to get a ticket from the server.
+ */
+
+ client_options.pk_alg = MBEDTLS_PK_ECDSA;
+ client_options.early_data = MBEDTLS_SSL_EARLY_DATA_ENABLED;
+ server_options.pk_alg = MBEDTLS_PK_ECDSA;
+ server_options.early_data = MBEDTLS_SSL_EARLY_DATA_ENABLED;
+ server_options.max_early_data_size = max_early_data_size_arg;
+
+ ret = mbedtls_test_get_tls13_ticket(&client_options, &server_options,
+ &saved_session);
+ TEST_EQUAL(ret, 0);
+
+ /*
+ * Prepare for handshake with the ticket.
+ */
+ ret = mbedtls_test_ssl_endpoint_init(&client_ep, MBEDTLS_SSL_IS_CLIENT,
+ &client_options, NULL, NULL, NULL);
+ TEST_EQUAL(ret, 0);
+
+ ret = mbedtls_test_ssl_endpoint_init(&server_ep, MBEDTLS_SSL_IS_SERVER,
+ &server_options, NULL, NULL, NULL);
+ TEST_EQUAL(ret, 0);
+
+ mbedtls_ssl_conf_session_tickets_cb(&server_ep.conf,
+ mbedtls_test_ticket_write,
+ mbedtls_test_ticket_parse,
+ NULL);
+
+ max_early_data_size = saved_session.max_early_data_size;
+ /*
+ * (max_early_data_size + 1024) for the size of the socket buffers for the
+ * server one to be able to contain the maximum number of early data bytes
+ * plus the first flight of client messages. Needed because we cannot
+ * initiate the handshake on server side before doing all the calls to
+ * mbedtls_ssl_write_early_data() we want to test. See below for more
+ * information.
+ */
+ ret = mbedtls_test_mock_socket_connect(&(client_ep.socket),
+ &(server_ep.socket),
+ max_early_data_size + 1024);
+ TEST_EQUAL(ret, 0);
+
+ /* If our server is configured with max_early_data_size equal to zero, it
+ * does not set the MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA flag for
+ * the tickets it creates. To be able to test early data with a ticket
+ * allowing early data in its flags but with max_early_data_size equal to
+ * zero (case supported by our client) tweak the ticket flags here.
+ */
+ if (max_early_data_size == 0) {
+ saved_session.ticket_flags |= MBEDTLS_SSL_TLS1_3_TICKET_ALLOW_EARLY_DATA;
+ }
+
+ ret = mbedtls_ssl_set_session(&(client_ep.ssl), &saved_session);
+ TEST_EQUAL(ret, 0);
+
+ while (written_early_data_size < max_early_data_size) {
+ uint32_t remaining = max_early_data_size - written_early_data_size;
+
+ for (size_t i = 0; i < buf_size; i++) {
+ buf[i] = (unsigned char) (written_early_data_size + i);
+ }
+
+ ret = mbedtls_ssl_write_early_data(&(client_ep.ssl),
+ buf,
+ buf_size);
+
+ if (buf_size <= remaining) {
+ TEST_EQUAL(ret, buf_size);
+ } else {
+ TEST_EQUAL(ret, remaining);
+ }
+ written_early_data_size += buf_size;
+ }
+ TEST_EQUAL(client_ep.ssl.total_early_data_size, max_early_data_size);
+
+ ret = mbedtls_ssl_write_early_data(&(client_ep.ssl), buf, 1);
+ TEST_EQUAL(ret, MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA);
+ TEST_EQUAL(client_ep.ssl.total_early_data_size, max_early_data_size);
+ TEST_EQUAL(client_ep.ssl.early_data_status,
+ MBEDTLS_SSL_EARLY_DATA_STATUS_CAN_WRITE);
+
+ /*
+ * Now, check data on server side. It is not done in the previous loop as
+ * in the first call to mbedtls_ssl_handshake(), the server ends up sending
+ * its Finished message and then in the following call to
+ * mbedtls_ssl_write_early_data() we go past the early data writing window
+ * and we cannot test multiple calls to the API is this writing window.
+ */
+ while (read_early_data_size < max_early_data_size) {
+ ret = mbedtls_ssl_handshake(&(server_ep.ssl));
+ TEST_EQUAL(ret, MBEDTLS_ERR_SSL_RECEIVED_EARLY_DATA);
+
+ ret = mbedtls_ssl_read_early_data(&(server_ep.ssl),
+ buf,
+ buf_size);
+ TEST_ASSERT(ret > 0);
+
+ for (size_t i = 0; i < (size_t) ret; i++) {
+ TEST_EQUAL(buf[i], (unsigned char) (read_early_data_size + i));
+ }
+
+ read_early_data_size += ret;
+ }
+ TEST_EQUAL(read_early_data_size, max_early_data_size);
+
+ ret = mbedtls_ssl_handshake(&(server_ep.ssl));
+ TEST_EQUAL(ret, MBEDTLS_ERR_SSL_WANT_READ);
+
+ TEST_ASSERT(mbedtls_test_move_handshake_to_state(
+ &(client_ep.ssl), &(server_ep.ssl), MBEDTLS_SSL_HANDSHAKE_OVER)
+ == 0);
+
+exit:
+ mbedtls_test_ssl_endpoint_free(&client_ep, NULL);
+ mbedtls_test_ssl_endpoint_free(&server_ep, NULL);
+ mbedtls_test_free_handshake_options(&client_options);
+ mbedtls_test_free_handshake_options(&server_options);
+ mbedtls_ssl_session_free(&saved_session);
+ mbedtls_free(buf);
+ PSA_DONE();
+}
+/* END_CASE */
+
/*
* The !MBEDTLS_SSL_PROTO_TLS1_2 dependency of tls13_early_data() below is
* a temporary workaround to not run the test in Windows-2013 where there is