Implement Extended ORPort authentication. (4a55e399) · Commits · The Tor Project / Core / Tor

src/or/connection_or.c

+241 −3

Original line number	Diff line number	Diff line
		@@ -2495,6 +2495,10 @@ connection_ext_or_transition(or_connection_t *conn)
		#define EXT_OR_PORT_AUTH_COOKIE_HEADER_LEN 32
		#define EXT_OR_PORT_AUTH_COOKIE_FILE_LEN EXT_OR_PORT_AUTH_COOKIE_LEN+EXT_OR_PORT_AUTH_COOKIE_HEADER_LEN
		#define EXT_OR_PORT_AUTH_COOKIE_HEADER "! Extended ORPort Auth Cookie !\x0a"
		#define EXT_OR_PORT_AUTH_HASH_LEN DIGEST256_LEN
		#define EXT_OR_PORT_AUTH_NONCE_LEN 32
		#define EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST "ExtORPort authentication server-to-client hash"
		#define EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST "ExtORPort authentication client-to-server hash"

		/** If true, we've set ext_or_auth_cookie to a secret code and stored
		* it to disk. */
		@@ -2569,6 +2573,194 @@ init_ext_or_auth_cookie_authentication(int is_enabled)
		#define EXT_OR_CMD_BT_DENY 0x1001
		#define EXT_OR_CMD_BT_CONTROL 0x1002

		/** DOCDOCDOC
		Return -1 on error. 0 on unsufficient data. 1 on correct.
		*/
		static int
		connection_ext_or_auth_neg_auth_type(connection_t conn) / XXX unit tests */
		{
		char authtype[1] = {0};

		if (connection_get_inbuf_len(conn) < 1)
		return 0;

		if (connection_fetch_from_buf(authtype, 1, conn) < 0)
		return -1;

		log_warn(LD_GENERAL, "Client wants us to use %d auth type", authtype[0]);
		if (authtype[0] != 1) /* '1' is the only auth type supported atm */
		return -1;

		conn->state = EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_NONCE; /* XXX maybe do state transition in process_inbuf ? */
		return 1;
		}

		static int
		connection_ext_or_auth_handle_client_nonce(connection_t *conn)
		{
		char server_hash[EXT_OR_PORT_AUTH_HASH_LEN] = {0};
		char client_nonce[EXT_OR_PORT_AUTH_NONCE_LEN] = {0};
		char server_nonce[EXT_OR_PORT_AUTH_NONCE_LEN] = {0};
		char reply[EXT_OR_PORT_AUTH_COOKIE_LEN+EXT_OR_PORT_AUTH_NONCE_LEN] = {0};

		if (!ext_or_auth_cookie_is_set) { /* this should not happen */
		log_warn(LD_BUG, "Extended ORPort authentication cookie was not set. "
		"That's weird since we should have done that on startup. "
		"This might be a Tor bug, please file a bug report. ");
		return -1;
		}

		if (connection_get_inbuf_len(conn) < EXT_OR_PORT_AUTH_NONCE_LEN)
		return 0;

		if (connection_fetch_from_buf(client_nonce, EXT_OR_PORT_AUTH_NONCE_LEN, conn) < 0) /* XXX check-spaces */
		return -1;

		/* Get our nonce */
		if (crypto_rand(server_nonce, EXT_OR_PORT_AUTH_NONCE_LEN) < 0)
		return -1;

		{ /* set up macs */
		size_t hmac_s_msg_len = strlen(EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST) +
		2*EXT_OR_PORT_AUTH_NONCE_LEN;
		size_t hmac_c_msg_len = strlen(EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST) +
		2*EXT_OR_PORT_AUTH_NONCE_LEN;

		char *hmac_s_msg = tor_malloc_zero(hmac_s_msg_len);
		char *hmac_c_msg = tor_malloc_zero(hmac_c_msg_len);
		char *correct_client_hash = tor_malloc_zero(EXT_OR_PORT_AUTH_HASH_LEN);

		memcpy(hmac_s_msg,
		EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST,
		strlen(EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST));
		memcpy(hmac_s_msg + strlen(EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST),
		client_nonce, EXT_OR_PORT_AUTH_NONCE_LEN);
		memcpy(hmac_s_msg + strlen(EXT_OR_PORT_AUTH_SERVER_TO_CLIENT_CONST) +
		EXT_OR_PORT_AUTH_NONCE_LEN,
		server_nonce, EXT_OR_PORT_AUTH_NONCE_LEN);

		memcpy(hmac_c_msg,
		EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST,
		strlen(EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST));
		memcpy(hmac_c_msg + strlen(EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST),
		client_nonce, EXT_OR_PORT_AUTH_NONCE_LEN);
		memcpy(hmac_c_msg + strlen(EXT_OR_PORT_AUTH_CLIENT_TO_SERVER_CONST) +
		EXT_OR_PORT_AUTH_NONCE_LEN,
		server_nonce, EXT_OR_PORT_AUTH_NONCE_LEN);

		crypto_hmac_sha256(server_hash,
		ext_or_auth_cookie,
		EXT_OR_PORT_AUTH_COOKIE_LEN,
		hmac_s_msg,
		hmac_s_msg_len);

		crypto_hmac_sha256(correct_client_hash,
		ext_or_auth_cookie,
		EXT_OR_PORT_AUTH_COOKIE_LEN,
		hmac_c_msg,
		hmac_c_msg_len);

		/* Store the client hash we generated. We will need to compare it
		with the hash sent by the client. */
		TO_OR_CONN(conn)->ext_or_auth_correct_client_hash = correct_client_hash;

		tor_free(hmac_s_msg);
		tor_free(hmac_c_msg);
		}

		{ /* debug logging / / XXX disable this codepath if not logging on debug? */
		char server_hash_encoded[(2*EXT_OR_PORT_AUTH_HASH_LEN) + 1];
		char server_nonce_encoded[(2*EXT_OR_PORT_AUTH_NONCE_LEN) + 1];
		char client_nonce_encoded[(2*EXT_OR_PORT_AUTH_NONCE_LEN) + 1];

		base16_encode(server_hash_encoded, sizeof(server_hash_encoded),
		server_hash, sizeof(server_hash));
		base16_encode(server_nonce_encoded, sizeof(server_nonce_encoded),
		server_nonce, sizeof(server_nonce));
		base16_encode(client_nonce_encoded, sizeof(client_nonce_encoded),
		client_nonce, sizeof(client_nonce));

		log_warn(LD_GENERAL, "server_hash: '%s'\nserver_nonce: '%s'\nclient_nonce: '%s'",
		server_hash_encoded, server_nonce_encoded, client_nonce_encoded);
		}

		{ /* write reply: (server_hash, server_nonce) */
		memcpy(reply, server_hash, EXT_OR_PORT_AUTH_HASH_LEN);
		memcpy(reply + EXT_OR_PORT_AUTH_HASH_LEN, server_nonce, EXT_OR_PORT_AUTH_NONCE_LEN);
		connection_write_to_buf(reply, sizeof(reply), conn);
		}

		log_warn(LD_GENERAL, "Got client nonce, and sent our own nonce and hash.");

		conn->state = EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_HASH;
		return 1;
		}

		#define connection_ext_or_auth_send_result_success(c) \
		connection_ext_or_auth_send_result(c, 1)
		#define connection_ext_or_auth_send_result_fail(c) \
		connection_ext_or_auth_send_result(c, 0)

		static void
		connection_ext_or_auth_send_result(connection_t *conn, int success)
		{
		if (success)
		connection_write_to_buf("\x01", 1, conn);
		else
		connection_write_to_buf("\x00", 1, conn);
		}

		static int
		connection_ext_or_auth_handle_client_hash(connection_t *conn)
		{
		char provided_client_hash[EXT_OR_PORT_AUTH_HASH_LEN] = {0};

		if (connection_get_inbuf_len(conn) < EXT_OR_PORT_AUTH_HASH_LEN)
		return 0;

		if (connection_fetch_from_buf(provided_client_hash, EXT_OR_PORT_AUTH_HASH_LEN, conn) < 0)
		return -1;

		if (tor_memneq(TO_OR_CONN(conn)->ext_or_auth_correct_client_hash,
		provided_client_hash, EXT_OR_PORT_AUTH_HASH_LEN)) {
		log_warn(LD_GENERAL, "Incorrect client hash. Authentication failed.");
		connection_ext_or_auth_send_result_fail(conn);
		return -1;
		}

		log_warn(LD_GENERAL, "Got client's hash and it was legit.");

		/* send positive auth result */
		connection_ext_or_auth_send_result_success(conn);
		conn->state = EXT_OR_CONN_STATE_OPEN;
		return 1;
		}

		/** DOCDOCDOC
		Return -1 on error. 0 on unsufficient data. 1 on correct.
		*/
		static int
		connection_ext_or_auth_process_inbuf(or_connection_t *or_conn)
		{
		connection_t *conn = TO_CONN(or_conn);

		switch (conn->state) { /* Functionify */
		case EXT_OR_CONN_STATE_AUTH_WAIT_AUTH_TYPE:
		return connection_ext_or_auth_neg_auth_type(conn);

		case EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_NONCE:
		return connection_ext_or_auth_handle_client_nonce(conn);

		case EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_HASH:
		return connection_ext_or_auth_handle_client_hash(conn);

		default:
		log_warn(LD_BUG, "Encountered unexpected connection state %d while trying "
		"to process Extended ORPort authentication data.", conn->state);
		return -1;
		}
		}

		/** Process Extended ORPort messages from <b>or_conn</b>. */
		int
		connection_ext_or_process_inbuf(or_connection_t *or_conn)
		@@ -2577,11 +2769,27 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)
		ext_or_cmd_t *command;
		int r;

		/* If we are still in the authentication stage, process traffic as
		authentication data: */
		while (conn->state <= EXT_OR_CONN_STATE_AUTH_MAX) {
		log_warn(LD_GENERAL, "Got Extended ORPort authentication data (%u).",
		(unsigned int) connection_get_inbuf_len(conn));
		r = connection_ext_or_auth_process_inbuf(or_conn);
		if (r < 0) {
		connection_mark_for_close(conn);
		return -1;
		} else if (r == 0) {
		return 0;
		}
		/* if r > 0, loop and process more data (if any). */
		}

		while (1) {
		log_warn(LD_GENERAL, "Got Extended ORPort data.");
		command = NULL;
		r = connection_fetch_ext_or_cmd_from_buf(conn, &command);
		if (r < 0)
		return -1;
		goto err;
		else if (r == 0)
		return 0; /* need to wait for more data */

		@@ -2602,6 +2810,9 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)
		conn->state = EXT_OR_CONN_STATE_FLUSHING;
		connection_stop_reading(conn);
		} else if (command->cmd == EXT_OR_CMD_TB_USERADDR) {
		/* XXX Put this in a function of its own. We need to empasize
		that we change the address and port of this connection. */

		/* Copy address string. */
		tor_addr_t addr;
		uint16_t port;
		@@ -2612,8 +2823,6 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)
		memcpy(addr_str, command->body, command->len);
		addr_str[command->len] = 0;

		log_debug(LD_NET, "Received USERADDR: '%s'!", addr_str);

		res = tor_addr_port_split(LOG_INFO, addr_str, &address_part, &port);
		tor_free(addr_str);
		if (res<0)
		@@ -2624,6 +2833,18 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)
		if (res<0)
		goto err;

		{
		char *old_address = tor_dup_addr(&conn->addr);
		char *new_address = tor_dup_addr(&addr);

		log_warn(LD_NET, "Received USERADDR." /* XXX FIX ALL LOG SEVERITIES AND MESSAGES */
		"We rewrite our address from '%s:%u' to '%s:%u'.",
		safe_str(old_address), conn->port, safe_str(new_address), port);

		tor_free(old_address);
		tor_free(new_address);
		}

		/* record the address */
		tor_addr_copy(&conn->addr, &addr);
		conn->port = port;
		@@ -2639,6 +2860,7 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)

		err:
		ext_or_cmd_free(command);
		connection_mark_for_close(conn);
		return -1;
		}

		@@ -2654,3 +2876,19 @@ connection_ext_or_finished_flushing(or_connection_t *conn)
		}
		return 0;
		}

		/* DOCDOCDOC */
		int
		connection_ext_or_start_auth(or_connection_t *or_conn)
		{
		connection_t *conn = TO_CONN(or_conn);
		char authtypes[2] = "\x01\x00"; /* We only support authtype '1' for now. */

		log_warn(LD_GENERAL,
		"ExtORPort authentication: Sending supported authentication types");

		connection_write_to_buf(authtypes, sizeof(authtypes), conn);
		conn->state = EXT_OR_CONN_STATE_AUTH_WAIT_AUTH_TYPE;

		return 0;
		}

src/or/connection_or.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -45,6 +45,8 @@ void connection_or_close_for_error(or_connection_t *orconn, int flush);

		void connection_or_report_broken_states(int severity, int domain);

		int connection_ext_or_start_auth(or_connection_t *or_conn);

		int connection_tls_start_handshake(or_connection_t *conn, int receiving);
		int connection_tls_continue_handshake(or_connection_t *conn);