diff options
Diffstat (limited to 'src/or/ext_orport.c')
| -rw-r--r-- | src/or/ext_orport.c | 648 |
1 files changed, 648 insertions, 0 deletions
diff --git a/src/or/ext_orport.c b/src/or/ext_orport.c new file mode 100644 index 000000000..0d28a9199 --- /dev/null +++ b/src/or/ext_orport.c @@ -0,0 +1,648 @@ +/* Copyright (c) 2012, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file ext_orport.c + * \brief Code implementing the Extended ORPort. +*/ + +#define EXT_ORPORT_PRIVATE +#include "or.h" +#include "connection.h" +#include "connection_or.h" +#include "ext_orport.h" +#include "control.h" +#include "config.h" +#include "util.h" +#include "main.h" + +/** Allocate and return a structure capable of holding an Extended + * ORPort message of body length <b>len</b>. */ +ext_or_cmd_t * +ext_or_cmd_new(uint16_t len) +{ + size_t size = STRUCT_OFFSET(ext_or_cmd_t, body) + len; + ext_or_cmd_t *cmd = tor_malloc(size); + cmd->len = len; + return cmd; +} + +/** Deallocate the Extended ORPort message in <b>cmd</b>. */ +void +ext_or_cmd_free(ext_or_cmd_t *cmd) +{ + tor_free(cmd); +} + +/** Get an Extended ORPort message from <b>conn</b>, and place it in + * <b>out</b>. Return -1 on fail, 0 if we need more data, and 1 if we + * successfully extracted an Extended ORPort command from the + * buffer. */ +static int +connection_fetch_ext_or_cmd_from_buf(connection_t *conn, ext_or_cmd_t **out) +{ + IF_HAS_BUFFEREVENT(conn, { + struct evbuffer *input = bufferevent_get_input(conn->bufev); + return fetch_ext_or_command_from_evbuffer(input, out); + }) ELSE_IF_NO_BUFFEREVENT { + return fetch_ext_or_command_from_buf(conn->inbuf, out); + } +} + +/** Write an Extended ORPort message to <b>conn</b>. Use + * <b>command</b> as the command type, <b>bodylen</b> as the body + * length, and <b>body</b>, if it's present, as the body of the + * message. */ +STATIC int +connection_write_ext_or_command(connection_t *conn, + uint16_t command, + const char *body, + size_t bodylen) +{ + char header[4]; + if (bodylen > UINT16_MAX) + return -1; + set_uint16(header, htons(command)); + set_uint16(header+2, htons(bodylen)); + connection_write_to_buf(header, 4, conn); + if (bodylen) { + tor_assert(body); + connection_write_to_buf(body, bodylen, conn); + } + return 0; +} + +/** Transition from an Extended ORPort which accepts Extended ORPort + * messages, to an Extended ORport which accepts OR traffic. */ +static void +connection_ext_or_transition(or_connection_t *conn) +{ + tor_assert(conn->base_.type == CONN_TYPE_EXT_OR); + + conn->base_.type = CONN_TYPE_OR; + TO_CONN(conn)->state = 0; // set the state to a neutral value + control_event_or_conn_status(conn, OR_CONN_EVENT_NEW, 0); + connection_tls_start_handshake(conn, 1); +} + +/** Length of authentication cookie. */ +#define EXT_OR_PORT_AUTH_COOKIE_LEN 32 +/** Length of the header of the cookie file. */ +#define EXT_OR_PORT_AUTH_COOKIE_HEADER_LEN 32 +/** Static cookie file header. */ +#define EXT_OR_PORT_AUTH_COOKIE_HEADER "! Extended ORPort Auth Cookie !\x0a" +/** Length of safe-cookie protocol hashes. */ +#define EXT_OR_PORT_AUTH_HASH_LEN DIGEST256_LEN +/** Length of safe-cookie protocol nonces. */ +#define EXT_OR_PORT_AUTH_NONCE_LEN 32 +/** Safe-cookie protocol constants. */ +#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" + +/* Code to indicate cookie authentication */ +#define EXT_OR_AUTHTYPE_SAFECOOKIE 0x01 + +/** If true, we've set ext_or_auth_cookie to a secret code and stored + * it to disk. */ +STATIC int ext_or_auth_cookie_is_set = 0; +/** If ext_or_auth_cookie_is_set, a secret cookie that we've stored to disk + * and which we're using to authenticate controllers. (If the controller can + * read it off disk, it has permission to connect.) */ +STATIC uint8_t *ext_or_auth_cookie = NULL; + +/** Helper: Return a newly allocated string containing a path to the + * file where we store our authentication cookie. */ +char * +get_ext_or_auth_cookie_file_name(void) +{ + const or_options_t *options = get_options(); + if (options->ExtORPortCookieAuthFile && + strlen(options->ExtORPortCookieAuthFile)) { + return tor_strdup(options->ExtORPortCookieAuthFile); + } else { + return get_datadir_fname("extended_orport_auth_cookie"); + } +} + +/* Initialize the cookie-based authentication system of the + * Extended ORPort. If <b>is_enabled</b> is 0, then disable the cookie + * authentication system. */ +int +init_ext_or_cookie_authentication(int is_enabled) +{ + char *fname = NULL; + int retval; + + if (!is_enabled) { + ext_or_auth_cookie_is_set = 0; + return 0; + } + + fname = get_ext_or_auth_cookie_file_name(); + retval = init_cookie_authentication(fname, EXT_OR_PORT_AUTH_COOKIE_HEADER, + EXT_OR_PORT_AUTH_COOKIE_HEADER_LEN, + &ext_or_auth_cookie, + &ext_or_auth_cookie_is_set); + tor_free(fname); + return retval; +} + +/** Read data from <b>conn</b> and see if the client sent us the + * authentication type that she prefers to use in this session. + * + * Return -1 if we received corrupted data or if we don't support the + * authentication type. Return 0 if we need more data in + * <b>conn</b>. Return 1 if the authentication type negotiation was + * successful. */ +static int +connection_ext_or_auth_neg_auth_type(connection_t *conn) +{ + 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_debug(LD_GENERAL, "Client wants us to use %d auth type", authtype[0]); + if (authtype[0] != EXT_OR_AUTHTYPE_SAFECOOKIE) { + /* '1' is the only auth type supported atm */ + return -1; + } + + conn->state = EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_NONCE; + return 1; +} + +/** DOCDOC */ +STATIC int +handle_client_auth_nonce(const char *client_nonce, size_t client_nonce_len, + char **client_hash_out, + char **reply_out, size_t *reply_len_out) +{ + char server_hash[EXT_OR_PORT_AUTH_HASH_LEN] = {0}; + char server_nonce[EXT_OR_PORT_AUTH_NONCE_LEN] = {0}; + char *reply; + size_t reply_len; + + if (client_nonce_len != EXT_OR_PORT_AUTH_NONCE_LEN) + 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, + (char*)ext_or_auth_cookie, + EXT_OR_PORT_AUTH_COOKIE_LEN, + hmac_s_msg, + hmac_s_msg_len); + + crypto_hmac_sha256(correct_client_hash, + (char*)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. */ + *client_hash_out = correct_client_hash; + + memwipe(hmac_s_msg, 0, hmac_s_msg_len); + memwipe(hmac_c_msg, 0, hmac_c_msg_len); + + 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, EXT_OR_PORT_AUTH_NONCE_LEN); + + log_debug(LD_GENERAL, + "server_hash: '%s'\nserver_nonce: '%s'\nclient_nonce: '%s'", + server_hash_encoded, server_nonce_encoded, client_nonce_encoded); + + memwipe(server_hash_encoded, 0, sizeof(server_hash_encoded)); + memwipe(server_nonce_encoded, 0, sizeof(server_nonce_encoded)); + memwipe(client_nonce_encoded, 0, sizeof(client_nonce_encoded)); + } + + { /* write reply: (server_hash, server_nonce) */ + + reply_len = EXT_OR_PORT_AUTH_COOKIE_LEN+EXT_OR_PORT_AUTH_NONCE_LEN; + reply = tor_malloc_zero(reply_len); + 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); + } + + *reply_out = reply; + *reply_len_out = reply_len; + + return 0; +} + +/** Read the client's nonce out of <b>conn</b>, setup the safe-cookie + * crypto, and then send our own hash and nonce to the client + * + * Return -1 if there was an error; return 0 if we need more data in + * <b>conn</b>, and return 1 if we successfully retrieved the + * client's nonce and sent our own. */ +static int +connection_ext_or_auth_handle_client_nonce(connection_t *conn) +{ + char client_nonce[EXT_OR_PORT_AUTH_NONCE_LEN]; + char *reply=NULL; + size_t reply_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) + return -1; + + /* We extract the ClientNonce from the received data, and use it to + calculate ServerHash and ServerNonce according to proposal 217. + + We also calculate our own ClientHash value and save it in the + connection state. We validate it later against the ClientHash + sent by the client. */ + if (handle_client_auth_nonce(client_nonce, sizeof(client_nonce), + &TO_OR_CONN(conn)->ext_or_auth_correct_client_hash, + &reply, &reply_len) < 0) + return -1; + + connection_write_to_buf(reply, reply_len, conn); + + memwipe(reply, 0, reply_len); + tor_free(reply); + + log_debug(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) + +/** Send authentication results to <b>conn</b>. Successful results if + * <b>success</b> is set; failure results otherwise. */ +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); +} + +/** Receive the client's hash from <b>conn</b>, validate that it's + * correct, and then send the authentication results to the client. + * + * Return -1 if there was an error during validation; return 0 if we + * need more data in <b>conn</b>, and return 1 if we successfully + * validated the client's hash and sent a happy authentication + * result. */ +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_debug(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; +} + +/** Handle data from <b>or_conn</b> received on Extended ORPort. + * 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); + + /* State transitions of the Extended ORPort authentication protocol: + + EXT_OR_CONN_STATE_AUTH_WAIT_AUTH_TYPE (start state) -> + EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_NONCE -> + EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_HASH -> + EXT_OR_CONN_STATE_OPEN + + During EXT_OR_CONN_STATE_OPEN, data is handled by + connection_ext_or_process_inbuf(). + */ + + 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; + } +} + +/** Extended ORPort commands (Transport-to-Bridge) */ +#define EXT_OR_CMD_TB_DONE 0x0000 +#define EXT_OR_CMD_TB_USERADDR 0x0001 +#define EXT_OR_CMD_TB_TRANSPORT 0x0002 + +/** Extended ORPort commands (Bridge-to-Transport) */ +#define EXT_OR_CMD_BT_OKAY 0x1000 +#define EXT_OR_CMD_BT_DENY 0x1001 +#define EXT_OR_CMD_BT_CONTROL 0x1002 + +/** Process a USERADDR command from the Extended + * ORPort. <b>payload</b> is a payload of size <b>len</b>. + * + * If the USERADDR command was well formed, change the address of + * <b>conn</b> to the address on the USERADDR command. + * + * Return 0 on success and -1 on error. */ +static int +connection_ext_or_handle_cmd_useraddr(connection_t *conn, + const char *payload, uint16_t len) +{ + /* Copy address string. */ + tor_addr_t addr; + uint16_t port; + char *addr_str; + char *address_part=NULL; + int res; + if (memchr(payload, '\0', len)) { + log_fn(LOG_PROTOCOL_WARN, LD_NET, "Unexpected NUL in ExtORPort UserAddr"); + return -1; + } + + addr_str = tor_memdup_nulterm(payload, len); + + res = tor_addr_port_split(LOG_INFO, addr_str, &address_part, &port); + tor_free(addr_str); + if (res<0) + return -1; + + res = tor_addr_parse(&addr, address_part); + tor_free(address_part); + if (res<0) + return -1; + + { /* do some logging */ + char *old_address = tor_dup_addr(&conn->addr); + char *new_address = tor_dup_addr(&addr); + + log_debug(LD_NET, "Received USERADDR." + "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; + if (conn->address) { + tor_free(conn->address); + } + conn->address = tor_dup_addr(&addr); + + return 0; +} + +/** Process a TRANSPORT command from the Extended + * ORPort. <b>payload</b> is a payload of size <b>len</b>. + * + * If the TRANSPORT command was well formed, register the name of the + * transport on <b>conn</b>. + * + * Return 0 on success and -1 on error. */ +static int +connection_ext_or_handle_cmd_transport(or_connection_t *conn, + const char *payload, uint16_t len) +{ + char *transport_str; + if (memchr(payload, '\0', len)) { + log_fn(LOG_PROTOCOL_WARN, LD_NET, "Unexpected NUL in ExtORPort Transport"); + return -1; + } + + transport_str = tor_memdup_nulterm(payload, len); + + /* Transport names MUST be C-identifiers. */ + if (!string_is_C_identifier(transport_str)) { + tor_free(transport_str); + return -1; + } + + /* If ext_or_transport is already occupied (because the PT sent two + * TRANSPORT commands), deallocate the old name and keep the new + * one */ + if (conn->ext_or_transport) + tor_free(conn->ext_or_transport); + + conn->ext_or_transport = transport_str; + return 0; +} + +#define EXT_OR_CONN_STATE_IS_AUTHENTICATING(st) \ + ((st) <= EXT_OR_CONN_STATE_AUTH_MAX) + +/** Process Extended ORPort messages from <b>or_conn</b>. */ +int +connection_ext_or_process_inbuf(or_connection_t *or_conn) +{ + connection_t *conn = TO_CONN(or_conn); + ext_or_cmd_t *command; + int r; + + /* DOCDOC Document the state machine and transitions in this function */ + + /* If we are still in the authentication stage, process traffic as + authentication data: */ + while (EXT_OR_CONN_STATE_IS_AUTHENTICATING(conn->state)) { + log_debug(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_debug(LD_GENERAL, "Got Extended ORPort data."); + command = NULL; + r = connection_fetch_ext_or_cmd_from_buf(conn, &command); + if (r < 0) + goto err; + else if (r == 0) + return 0; /* need to wait for more data */ + + /* Got a command! */ + tor_assert(command); + + if (command->cmd == EXT_OR_CMD_TB_DONE) { + if (connection_get_inbuf_len(conn)) { + /* The inbuf isn't empty; the client is misbehaving. */ + goto err; + } + + log_debug(LD_NET, "Received DONE."); + + /* If the transport proxy did not use the TRANSPORT command to + * specify the transport name, mark this as unknown transport. */ + if (!or_conn->ext_or_transport) { + /* We write this string this way to avoid ??>, which is a C + * trigraph. */ + or_conn->ext_or_transport = tor_strdup("<?" "?>"); + } + + connection_write_ext_or_command(conn, EXT_OR_CMD_BT_OKAY, NULL, 0); + + /* can't transition immediately; need to flush first. */ + conn->state = EXT_OR_CONN_STATE_FLUSHING; + connection_stop_reading(conn); + } else if (command->cmd == EXT_OR_CMD_TB_USERADDR) { + if (connection_ext_or_handle_cmd_useraddr(conn, + command->body, command->len) < 0) + goto err; + } else if (command->cmd == EXT_OR_CMD_TB_TRANSPORT) { + if (connection_ext_or_handle_cmd_transport(or_conn, + command->body, command->len) < 0) + goto err; + } else { + log_notice(LD_NET,"Got Extended ORPort command we don't regognize (%u).", + command->cmd); + } + + ext_or_cmd_free(command); + } + + return 0; + + err: + ext_or_cmd_free(command); + connection_mark_for_close(conn); + return -1; +} + +/** <b>conn</b> finished flushing Extended ORPort messages to the + * network, and is now ready to accept OR traffic. This function + * does the transition. */ +int +connection_ext_or_finished_flushing(or_connection_t *conn) +{ + if (conn->base_.state == EXT_OR_CONN_STATE_FLUSHING) { + connection_start_reading(TO_CONN(conn)); + connection_ext_or_transition(conn); + } + return 0; +} + +/** Initiate Extended ORPort authentication, by sending the list of + * supported authentication types to the client. */ +int +connection_ext_or_start_auth(or_connection_t *or_conn) +{ + connection_t *conn = TO_CONN(or_conn); + const uint8_t authtypes[] = { + /* We only support authtype '1' for now. */ + EXT_OR_AUTHTYPE_SAFECOOKIE, + /* Marks the end of the list. */ + 0 + }; + + log_debug(LD_GENERAL, + "ExtORPort authentication: Sending supported authentication types"); + + connection_write_to_buf((const char *)authtypes, sizeof(authtypes), conn); + conn->state = EXT_OR_CONN_STATE_AUTH_WAIT_AUTH_TYPE; + + return 0; +} + +/** Free any leftover allocated memory of the ext_orport.c subsystem. */ +void +ext_orport_free_all(void) +{ + if (ext_or_auth_cookie) /* Free the auth cookie */ + tor_free(ext_or_auth_cookie); +} + |