X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fprotocol.c;h=cf5cd6773c3e6aa57f58be0dcae2dfbf6db14149;hp=31d22064541658082f986741097036a056640744;hb=4f9dad0972ac0f665a1b6050b059bd52f93e6221;hpb=54881faf6fdbf04fb5ee56b7809439fbc50c65cb diff --git a/src/protocol.c b/src/protocol.c index 31d22064..cf5cd677 100644 --- a/src/protocol.c +++ b/src/protocol.c @@ -17,7 +17,7 @@ along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - $Id: protocol.c,v 1.28.4.80 2001/02/25 16:34:19 guus Exp $ + $Id: protocol.c,v 1.28.4.92 2001/06/05 16:09:55 guus Exp $ */ #include "config.h" @@ -68,6 +68,8 @@ #include "system.h" +int mykeyused = 0; + int check_id(char *id) { int i; @@ -104,11 +106,15 @@ cp return -1; } - len++; - if(debug_lvl >= DEBUG_PROTOCOL) - syslog(LOG_DEBUG, _("Sending %s to %s (%s)"), request_name[request], cl->name, cl->hostname); + { + if(debug_lvl >= DEBUG_META) + syslog(LOG_DEBUG, _("Sending %s to %s (%s): %s"), request_name[request], cl->name, cl->hostname, buffer); + else + syslog(LOG_DEBUG, _("Sending %s to %s (%s)"), request_name[request], cl->name, cl->hostname); + } + buffer[len++] = '\n'; cp return send_meta(cl, buffer, len); } @@ -116,20 +122,31 @@ cp int receive_request(connection_t *cl) { int request; -cp +cp if(sscanf(cl->buffer, "%d", &request) == 1) { - if((request < 0) || (request > 255) || (request_handlers[request] == NULL)) + if((request < 0) || (request >= LAST) || (request_handlers[request] == NULL)) { - syslog(LOG_ERR, _("Unknown request from %s (%s)"), - cl->name, cl->hostname); + if(debug_lvl >= DEBUG_META) + syslog(LOG_DEBUG, _("Unknown request from %s (%s): %s"), + cl->name, cl->hostname, cl->buffer); + else + syslog(LOG_ERR, _("Unknown request from %s (%s)"), + cl->name, cl->hostname); + return -1; } else { if(debug_lvl >= DEBUG_PROTOCOL) - syslog(LOG_DEBUG, _("Got %s from %s (%s)"), - request_name[request], cl->name, cl->hostname); + { + if(debug_lvl >= DEBUG_META) + syslog(LOG_DEBUG, _("Got %s from %s (%s): %s"), + request_name[request], cl->name, cl->hostname, cl->buffer); + else + syslog(LOG_DEBUG, _("Got %s from %s (%s)"), + request_name[request], cl->name, cl->hostname); + } } if((cl->allow_request != ALL) && (cl->allow_request != request)) @@ -156,39 +173,11 @@ cp return 0; } -/* Connection protocol: - - Client Server - send_id(u) - send_challenge(R) - send_chal_reply(H) - send_id(u) - send_challenge(R) - send_chal_reply(H) - --------------------------------------- - send_metakey(R) - send_metakey(R) - --------------------------------------- - send_ack(u) - send_ack(u) - --------------------------------------- - Other requests(E)... - - (u) Unencrypted, - (R) RSA, - (H) SHA1, - (E) Encrypted with symmetric cipher. - - Part of the challenge is directly used to set the symmetric cipher - key and the initial vector. Since a man-in-the-middle cannot - decrypt the RSA challenges, this means that he cannot get or forge - the key for the symmetric cipher. -*/ +/* The authentication protocol is described in detail in doc/SECURITY2, + the rest will be described in doc/PROTOCOL. */ int send_id(connection_t *cl) { -cp - cl->allow_request = CHALLENGE; cp return send_request(cl, "%d %s %d %lx %hd", ID, myself->name, myself->protocol_version, myself->options, myself->port); } @@ -225,6 +214,9 @@ cp /* Copy string to cl */ + if(cl->name) + free(cl->name); + cl->name = xstrdup(name); /* Load information about peer */ @@ -263,13 +255,97 @@ cp cl->port = port; avl_insert_node(connection_tree, node); - /* Read in the public key, so that we can send a challenge */ + /* Read in the public key, so that we can send a metakey */ if(read_rsa_public_key(cl)) return -1; + cl->allow_request = METAKEY; cp - return send_challenge(cl); + return send_metakey(cl); +} + +int ack_h(connection_t *cl) +{ + config_t const *cfg; + connection_t *old, *p; + subnet_t *subnet; + avl_node_t *node, *node2; +cp + /* Okay, before we active the connection, we check if there is another entry + in the connection list with the same name. If so, it presumably is an + old connection that has timed out but we don't know it yet. + */ + + while((old = lookup_id(cl->name))) + { + if(debug_lvl >= DEBUG_CONNECTIONS) + syslog(LOG_NOTICE, _("Removing old entry for %s at %s in favour of new connection from %s"), + cl->name, old->hostname, cl->hostname); + + terminate_connection(old); + } + + /* Activate this connection */ + + cl->allow_request = ALL; + cl->status.active = 1; + cl->nexthop = cl; + cl->cipher_pkttype = EVP_bf_cbc(); + cl->cipher_pktkeylength = cl->cipher_pkttype->key_len + cl->cipher_pkttype->iv_len; + + if(debug_lvl >= DEBUG_CONNECTIONS) + syslog(LOG_NOTICE, _("Connection with %s (%s) activated"), cl->name, cl->hostname); + +cp + /* Check some options */ + + if((cfg = get_config_val(cl->config, config_indirectdata))) + { + if(cfg->data.val == stupid_true) + cl->options |= OPTION_INDIRECT; + } + + if((cfg = get_config_val(cl->config, config_tcponly))) + { + if(cfg->data.val == stupid_true) + cl->options |= OPTION_TCPONLY; + } + + /* Send him our subnets */ + + for(node = myself->subnet_tree->head; node; node = node->next) + { + subnet = (subnet_t *)node->data; + send_add_subnet(cl, subnet); + } + + /* And send him all the hosts and their subnets we know... */ + + for(node = connection_tree->head; node; node = node->next) + { + p = (connection_t *)node->data; + + if(p != cl && p->status.active) + { + /* Notify others of this connection */ + + if(p->status.meta) + send_add_host(p, cl); + + /* Notify new connection of everything we know */ + + send_add_host(cl, p); + + for(node2 = p->subnet_tree->head; node2; node2 = node2->next) + { + subnet = (subnet_t *)node2->data; + send_add_subnet(cl, subnet); + } + } + } +cp + return 0; } int send_challenge(connection_t *cl) @@ -277,6 +353,8 @@ int send_challenge(connection_t *cl) char *buffer; int len, x; cp + /* CHECKME: what is most reasonable value for len? */ + len = RSA_size(cl->rsa_key); /* Allocate buffers for the challenge */ @@ -292,32 +370,15 @@ cp RAND_bytes(cl->hischallenge, len); - cl->hischallenge[0] &= 0x7F; /* Somehow if the first byte is more than 0xD0 or something like that, decryption fails... */ -cp - if(debug_lvl >= DEBUG_SCARY_THINGS) - { - bin2hex(cl->hischallenge, buffer, len); - buffer[len*2] = '\0'; - syslog(LOG_DEBUG, _("Generated random challenge (unencrypted): %s"), buffer); - } - - /* Encrypt the random data */ - - if(RSA_public_encrypt(len, cl->hischallenge, buffer, cl->rsa_key, RSA_NO_PADDING) != len) /* NO_PADDING because the message size equals the RSA key size and it is totally random */ - { - syslog(LOG_ERR, _("Error during encryption of challenge for %s (%s)"), cl->name, cl->hostname); - free(buffer); - return -1; - } cp - /* Convert the encrypted random data to a hexadecimal formatted string */ + /* Convert to hex */ - bin2hex(buffer, buffer, len); + bin2hex(cl->hischallenge, buffer, len); buffer[len*2] = '\0'; + cp /* Send the challenge */ - cl->allow_request = CHAL_REPLY; x = send_request(cl, "%d %s", CHALLENGE, buffer); free(buffer); cp @@ -352,22 +413,9 @@ cp /* Convert the challenge from hexadecimal back to binary */ - hex2bin(buffer,buffer,len); - - /* Decrypt the challenge */ - - if(RSA_private_decrypt(len, buffer, cl->mychallenge, myself->rsa_key, RSA_NO_PADDING) != len) /* See challenge() */ - { - syslog(LOG_ERR, _("Error during encryption of challenge for %s (%s)"), cl->name, cl->hostname); - return -1; - } + hex2bin(buffer,cl->mychallenge,len); - if(debug_lvl >= DEBUG_SCARY_THINGS) - { - bin2hex(cl->mychallenge, buffer, len); - buffer[len*2] = '\0'; - syslog(LOG_DEBUG, _("Received random challenge (unencrypted): %s"), buffer); - } + cl->allow_request = CHAL_REPLY; /* Rest is done by send_chal_reply() */ cp @@ -395,11 +443,6 @@ cp /* Send the reply */ - if(cl->status.outgoing) - cl->allow_request = ID; - else - cl->allow_request = METAKEY; - cp return send_request(cl, "%d %s", CHAL_REPLY, hash); } @@ -445,16 +488,11 @@ cp return -1; } - /* Identity has now been positively verified. - If we are accepting this new connection, then send our identity, - if we are making this connecting, acknowledge. + ack_h() handles the rest from now on. */ cp - if(cl->status.outgoing) - return send_metakey(cl); - else - return send_id(cl); + return ack_h(cl); } int send_metakey(connection_t *cl) @@ -478,8 +516,18 @@ cp RAND_bytes(cl->cipher_outkey, len); - cl->cipher_outkey[0] &= 0x7F; /* FIXME: Somehow if the first byte is more than 0xD0 or something like that, decryption fails... */ - + /* The message we send must be smaller than the modulus of the RSA key. + By definition, for a key of k bits, the following formula holds: + + 2^(k-1) <= modulus < 2^(k) + + Where ^ means "to the power of", not "xor". + This means that to be sure, we must choose our message < 2^(k-1). + This can be done by setting the most significant bit to zero. + */ + + cl->cipher_outkey[0] &= 0x7F; + if(debug_lvl >= DEBUG_SCARY_THINGS) { bin2hex(cl->cipher_outkey, buffer, len); @@ -487,9 +535,14 @@ cp syslog(LOG_DEBUG, _("Generated random meta key (unencrypted): %s"), buffer); } - /* Encrypt the random data */ + /* Encrypt the random data - if(RSA_public_encrypt(len, cl->cipher_outkey, buffer, cl->rsa_key, RSA_NO_PADDING) != len) /* NO_PADDING because the message size equals the RSA key size and it is totally random */ + We do not use one of the PKCS padding schemes here. + This is allowed, because we encrypt a totally random string + with a length equal to that of the modulus of the RSA key. + */ + + if(RSA_public_encrypt(len, cl->cipher_outkey, buffer, cl->rsa_key, RSA_NO_PADDING) != len) { syslog(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), cl->name, cl->hostname); free(buffer); @@ -503,15 +556,16 @@ cp /* Send the meta key */ - if(cl->status.outgoing) - cl->allow_request = METAKEY; - else - cl->allow_request = ACK; - x = send_request(cl, "%d %s", METAKEY, buffer); free(buffer); - EVP_EncryptInit(cl->cipher_outctx, EVP_bf_cfb(), cl->cipher_outkey, cl->cipher_outkey + EVP_bf_cfb()->key_len); + /* Further outgoing requests are encrypted with the key we just generated */ + + EVP_EncryptInit(cl->cipher_outctx, EVP_bf_cfb(), + cl->cipher_outkey + len - EVP_bf_cfb()->key_len, + cl->cipher_outkey + len - EVP_bf_cfb()->key_len - EVP_bf_cfb()->iv_len); + + cl->status.encryptout = 1; cp return x; } @@ -564,112 +618,17 @@ cp syslog(LOG_DEBUG, _("Received random meta key (unencrypted): %s"), buffer); } - EVP_DecryptInit(cl->cipher_inctx, EVP_bf_cfb(), cl->cipher_inkey, cl->cipher_inkey + EVP_bf_cfb()->key_len); - -cp - if(cl->status.outgoing) - return send_ack(cl); - else - return send_metakey(cl); -} - -int send_ack(connection_t *cl) -{ - int x; -cp - if(cl->status.outgoing) - cl->allow_request = ACK; - - x = send_request(cl, "%d", ACK); - cl->status.encryptout = 1; -cp - return x; -} - -int ack_h(connection_t *cl) -{ - config_t const *cfg; - connection_t *old, *p; - subnet_t *subnet; - avl_node_t *node, *node2; -cp - /* Okay, before we active the connection, we check if there is another entry - in the connection list with the same name. If so, it presumably is an - old connection that has timed out but we don't know it yet. - */ - - while((old = lookup_id(cl->name))) - { - if(debug_lvl >= DEBUG_CONNECTIONS) - syslog(LOG_NOTICE, _("Removing old entry for %s at %s in favour of new connection from %s"), - cl->name, old->hostname, cl->hostname); - - terminate_connection(old); - } - - /* Activate this connection */ - - cl->allow_request = ALL; - cl->status.active = 1; - cl->status.decryptin = 1; - cl->nexthop = cl; - cl->cipher_pkttype = EVP_bf_cbc(); - cl->cipher_pktkeylength = cl->cipher_pkttype->key_len + cl->cipher_pkttype->iv_len; - - if(debug_lvl >= DEBUG_CONNECTIONS) - syslog(LOG_NOTICE, _("Connection with %s (%s) activated"), cl->name, cl->hostname); - -cp - if(!cl->status.outgoing) - send_ack(cl); - - /* Check some options */ - - if((cfg = get_config_val(cl->config, config_indirectdata))) - { - if(cfg->data.val == stupid_true) - cl->options |= OPTION_INDIRECT; - } - - if((cfg = get_config_val(cl->config, config_tcponly))) - { - if(cfg->data.val == stupid_true) - cl->options |= OPTION_TCPONLY; - } + /* All incoming requests will now be encrypted. */ - /* Send him our subnets */ + EVP_DecryptInit(cl->cipher_inctx, EVP_bf_cfb(), + cl->cipher_inkey + len - EVP_bf_cfb()->key_len, + cl->cipher_inkey + len - EVP_bf_cfb()->key_len - EVP_bf_cfb()->iv_len); - for(node = myself->subnet_tree->head; node; node = node->next) - { - subnet = (subnet_t *)node->data; - send_add_subnet(cl, subnet); - } - /* And send him all the hosts and their subnets we know... */ - - for(node = connection_tree->head; node; node = node->next) - { - p = (connection_t *)node->data; - - if(p != cl && p->status.active) - { - /* Notify others of this connection */ - - if(p->status.meta) - send_add_host(p, cl); - - /* Notify new connection of everything we know */ - - send_add_host(cl, p); + cl->status.decryptin = 1; - for(node2 = p->subnet_tree->head; node2; node2 = node2->next) - { - subnet = (subnet_t *)node2->data; - send_add_subnet(cl, subnet); - } - } - } + cl->allow_request = CHALLENGE; cp - return 0; + return send_challenge(cl); } /* Address and subnet information exchange */ @@ -680,7 +639,7 @@ int send_add_subnet(connection_t *cl, subnet_t *subnet) char *netstr; char *owner; cp - if(cl->options & OPTION_INDIRECT) + if((cl->options | myself->options | subnet->owner->options) & OPTION_INDIRECT) owner = myself->name; else owner = subnet->owner->name; @@ -846,9 +805,11 @@ cp int send_add_host(connection_t *cl, connection_t *other) { cp - if(!(cl->options & OPTION_INDIRECT)) + if(!((cl->options | myself->options | other->options) & OPTION_INDIRECT)) return send_request(cl, "%d %s %lx:%d %lx", ADD_HOST, other->name, other->address, other->port, other->options); + else + return 0; } int add_host_h(connection_t *cl) @@ -859,7 +820,7 @@ int add_host_h(connection_t *cl) cp new = new_connection(); - if(sscanf(cl->buffer, "%*d "MAX_STRING" %lx:%d %lx", name, &new->address, &new->port, &new->options) != 4) + if(sscanf(cl->buffer, "%*d "MAX_STRING" %lx:%hd %lx", name, &new->address, &new->port, &new->options) != 4) { syslog(LOG_ERR, _("Got bad ADD_HOST from %s (%s)"), cl->name, cl->hostname); return -1; @@ -938,21 +899,23 @@ cp int send_del_host(connection_t *cl, connection_t *other) { cp - if(!(cl->options & OPTION_INDIRECT)) + if(!((cl->options | myself->options) & OPTION_INDIRECT)) return send_request(cl, "%d %s %lx:%d %lx", DEL_HOST, other->name, other->address, other->port, other->options); + else + return 0; } int del_host_h(connection_t *cl) { char name[MAX_STRING_SIZE]; - ip_t address; + ipv4_t address; port_t port; long int options; connection_t *old, *p; avl_node_t *node; cp - if(sscanf(cl->buffer, "%*d "MAX_STRING" %lx:%d %lx", name, &address, &port, &options) != 4) + if(sscanf(cl->buffer, "%*d "MAX_STRING" %lx:%hd %lx", name, &address, &port, &options) != 4) { syslog(LOG_ERR, _("Got bad DEL_HOST from %s (%s)"), cl->name, cl->hostname); @@ -1091,11 +1054,15 @@ cp int send_ping(connection_t *cl) { + char salt[SALTLEN*2+1]; cp cl->status.pinged = 1; cl->last_ping_time = time(NULL); + RAND_bytes(salt, SALTLEN); + bin2hex(salt, salt, SALTLEN); + salt[SALTLEN*2] = '\0'; cp - return send_request(cl, "%d", PING); + return send_request(cl, "%d %s", PING, salt); } int ping_h(connection_t *cl) @@ -1106,8 +1073,13 @@ cp int send_pong(connection_t *cl) { + char salt[SALTLEN*2+1]; cp - return send_request(cl, "%d", PONG); + RAND_bytes(salt, SALTLEN); + bin2hex(salt, salt, SALTLEN); + salt[SALTLEN*2] = '\0'; +cp + return send_request(cl, "%d %s", PONG, salt); } int pong_h(connection_t *cl) @@ -1125,13 +1097,21 @@ int send_key_changed(connection_t *from, connection_t *cl) connection_t *p; avl_node_t *node; cp - for(node = connection_tree->head; node; node = node->next) + /* Only send this message if some other daemon requested our key previously. + This reduces unnecessary key_changed broadcasts. + */ + + if(mykeyused) { - p = (connection_t *)node->data; - if(p != cl && p->status.meta && p->status.active) - if(!(p->options & OPTION_INDIRECT) || from == myself) - send_request(p, "%d %s", KEY_CHANGED, from->name); - } + for(node = connection_tree->head; node; node = node->next) + { + p = (connection_t *)node->data; + if(p != cl && p->status.meta && p->status.active) + if(!(p->options & OPTION_INDIRECT) || from == myself) + send_request(p, "%d %s", KEY_CHANGED, from->name); + } + mykeyused = 0; + } cp return 0; } @@ -1158,7 +1138,8 @@ cp from->status.validkey = 0; from->status.waitingforkey = 0; - send_key_changed(from, cl); + if(!(from->options | cl->options | myself->options) & OPTION_INDIRECT) + send_key_changed(from, cl); cp return 0; } @@ -1193,11 +1174,12 @@ cp /* Check if this key request is for us */ - if(!strcmp(to_id, myself->name)) + if(!strcmp(to_id, myself->name)) /* Yes, send our own key back */ { bin2hex(myself->cipher_pktkey, pktkey, myself->cipher_pktkeylength); pktkey[myself->cipher_pktkeylength*2] = '\0'; send_ans_key(myself, from, pktkey); + mykeyused = 1; } else { @@ -1296,60 +1278,38 @@ cp int send_tcppacket(connection_t *cl, vpn_packet_t *packet) { int x; - +cp + /* Evil hack. */ + x = send_request(cl->nexthop, "%d %hd", PACKET, packet->len); if(x) return x; - - return send_meta(cl->nexthop, packet->data, packet->len); +cp + return send_meta(cl, packet->data, packet->len); } int tcppacket_h(connection_t *cl) { - vpn_packet_t packet; - char *p; - int todo, x; - - if(sscanf(cl->buffer, "%*d %hd", packet.len) != 1) + short int len; +cp + if(sscanf(cl->buffer, "%*d %hd", &len) != 1) { syslog(LOG_ERR, _("Got bad PACKET from %s (%s)"), cl->name, cl->hostname); return -1; } - /* Evil hack. */ + /* Set reqlen to len, this will tell receive_meta() that a tcppacket is coming. */ - p = packet.data; - todo = packet.len; - - while(todo) - { - x = read(cl->meta_socket, p, todo); - - if(x<=0) - { - if(x==0) - syslog(LOG_NOTICE, _("Connection closed by %s (%s)"), cl->name, cl->hostname); - else - if(errno==EINTR) - continue; - else - syslog(LOG_ERR, _("Error during reception of PACKET from %s (%s): %m"), cl->name, cl->hostname); - - return -1; - } - - todo -= x; - p += x; - } - - return receive_packet(cl, &packet); + cl->tcplen = len; +cp + return 0; } /* Jumptable for the request handlers */ int (*request_handlers[])(connection_t*) = { - id_h, challenge_h, chal_reply_h, metakey_h, ack_h, + id_h, metakey_h, challenge_h, chal_reply_h, status_h, error_h, termreq_h, ping_h, pong_h, add_host_h, del_host_h, @@ -1361,7 +1321,7 @@ int (*request_handlers[])(connection_t*) = { /* Request names */ char (*request_name[]) = { - "ID", "CHALLENGE", "CHAL_REPLY", "METAKEY", "ACK", + "ID", "METAKEY", "CHALLENGE", "CHAL_REPLY", "STATUS", "ERROR", "TERMREQ", "PING", "PONG", "ADD_HOST", "DEL_HOST",