/* protocol_auth.c -- handle the meta-protocol, authentication Copyright (C) 1999-2005 Ivo Timmermans, 2000-2010 Guus Sliepen This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "system.h" #include "splay_tree.h" #include "conf.h" #include "connection.h" #include "control.h" #include "control_common.h" #include "cipher.h" #include "crypto.h" #include "digest.h" #include "edge.h" #include "graph.h" #include "logger.h" #include "net.h" #include "netutl.h" #include "node.h" #include "prf.h" #include "protocol.h" #include "rsa.h" #include "utils.h" #include "xalloc.h" bool send_id(connection_t *c) { gettimeofday(&c->start, NULL); int minor = 0; if(experimental) { if(c->config_tree && !read_ecdsa_public_key(c)) minor = 1; else minor = myself->connection->protocol_minor; } return send_request(c, "%d %s %d.%d", ID, myself->connection->name, myself->connection->protocol_major, minor); } bool id_h(connection_t *c, char *request) { char name[MAX_STRING_SIZE]; if(sscanf(request, "%*d " MAX_STRING " %d.%d", name, &c->protocol_major, &c->protocol_minor) < 2) { logger(LOG_ERR, "Got bad %s from %s (%s)", "ID", c->name, c->hostname); return false; } /* Check if this is a control connection */ if(name[0] == '^' && !strcmp(name + 1, controlcookie)) { c->status.control = true; c->allow_request = CONTROL; c->last_ping_time = time(NULL) + 3600; return send_request(c, "%d %d %d", ACK, TINC_CTL_VERSION_CURRENT, getpid()); } /* Check if identity is a valid name */ if(!check_id(name)) { logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ID", c->name, c->hostname, "invalid name"); return false; } /* If this is an outgoing connection, make sure we are connected to the right host */ if(c->outgoing) { if(strcmp(c->name, name)) { logger(LOG_ERR, "Peer %s is %s instead of %s", c->hostname, name, c->name); return false; } } else { if(c->name) free(c->name); c->name = xstrdup(name); } /* Check if version matches */ if(c->protocol_major != myself->connection->protocol_major) { logger(LOG_ERR, "Peer %s (%s) uses incompatible version %d.%d", c->name, c->hostname, c->protocol_major, c->protocol_minor); return false; } if(bypass_security) { if(!c->config_tree) init_configuration(&c->config_tree); c->allow_request = ACK; return send_ack(c); } if(!experimental) c->protocol_minor = 0; if(!c->config_tree) { init_configuration(&c->config_tree); if(!read_connection_config(c)) { logger(LOG_ERR, "Peer %s had unknown identity (%s)", c->hostname, c->name); return false; } if(experimental && c->protocol_minor >= 2) if(!read_ecdsa_public_key(c)) return false; } else { if(c->protocol_minor && !ecdsa_active(&c->ecdsa)) c->protocol_minor = 1; } c->allow_request = METAKEY; if(c->protocol_minor >= 2) return send_metakey_ec(c); else return send_metakey(c); } bool send_metakey_ec(connection_t *c) { logger(LOG_DEBUG, "Sending ECDH metakey to %s", c->name); size_t siglen = ecdsa_size(&myself->connection->ecdsa); char key[(ECDH_SIZE + siglen) * 2 + 1]; // TODO: include nonce? Use relevant parts of SSH or TLS protocol if(!ecdh_generate_public(&c->ecdh, key)) return false; if(!ecdsa_sign(&myself->connection->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE)) return false; b64encode(key, key, ECDH_SIZE + siglen); return send_request(c, "%d %s", METAKEY, key); } bool send_metakey(connection_t *c) { if(!read_rsa_public_key(c)) return false; if(!cipher_open_blowfish_ofb(&c->outcipher)) return false; if(!digest_open_sha1(&c->outdigest, -1)) return false; size_t len = rsa_size(&c->rsa); char key[len]; char enckey[len]; char hexkey[2 * len + 1]; /* Create a random key */ randomize(key, len); /* 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. */ key[0] &= 0x7F; cipher_set_key_from_rsa(&c->outcipher, key, len, true); ifdebug(SCARY_THINGS) { bin2hex(key, hexkey, len); logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s", hexkey); } /* Encrypt the random data 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(&c->rsa, key, len, enckey)) { logger(LOG_ERR, "Error during encryption of meta key for %s (%s)", c->name, c->hostname); return false; } /* Convert the encrypted random data to a hexadecimal formatted string */ bin2hex(enckey, hexkey, len); /* Send the meta key */ bool result = send_request(c, "%d %d %d %d %d %s", METAKEY, cipher_get_nid(&c->outcipher), digest_get_nid(&c->outdigest), c->outmaclength, c->outcompression, hexkey); c->status.encryptout = true; return result; } static bool metakey_ec_h(connection_t *c, const char *request) { size_t siglen = ecdsa_size(&c->ecdsa); char key[MAX_STRING_SIZE]; char sig[siglen]; logger(LOG_DEBUG, "Got ECDH metakey from %s", c->name); if(sscanf(request, "%*d " MAX_STRING, key) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname); return false; } int inlen = b64decode(key, key, sizeof key); if(inlen != (ECDH_SIZE + siglen)) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength"); return false; } if(!ecdsa_verify(&c->ecdsa, key, ECDH_SIZE, key + ECDH_SIZE)) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "invalid ECDSA signature"); return false; } char shared[ECDH_SHARED_SIZE]; if(!ecdh_compute_shared(&c->ecdh, key, shared)) return false; /* Update our crypto end */ if(!cipher_open_by_name(&c->incipher, "aes-256-ofb")) return false; if(!digest_open_by_name(&c->indigest, "sha512", -1)) return false; if(!cipher_open_by_name(&c->outcipher, "aes-256-ofb")) return false; if(!digest_open_by_name(&c->outdigest, "sha512", -1)) return false; size_t mykeylen = cipher_keylength(&c->incipher); size_t hiskeylen = cipher_keylength(&c->outcipher); char *mykey; char *hiskey; char *seed; if(strcmp(myself->name, c->name) < 0) { mykey = key; hiskey = key + mykeylen * 2; xasprintf(&seed, "tinc TCP key expansion %s %s", myself->name, c->name); } else { mykey = key + hiskeylen * 2; hiskey = key; xasprintf(&seed, "tinc TCP key expansion %s %s", c->name, myself->name); } if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2)) return false; free(seed); cipher_set_key(&c->incipher, mykey, false); digest_set_key(&c->indigest, mykey + mykeylen, mykeylen); cipher_set_key(&c->outcipher, hiskey, true); digest_set_key(&c->outdigest, hiskey + hiskeylen, hiskeylen); c->status.decryptin = true; c->status.encryptout = true; c->allow_request = CHALLENGE; return send_challenge(c); } bool metakey_h(connection_t *c, char *request) { if(c->protocol_minor >= 2) return metakey_ec_h(c, request); char hexkey[MAX_STRING_SIZE]; int cipher, digest, maclength, compression; size_t len = rsa_size(&myself->connection->rsa); char enckey[len]; char key[len]; if(sscanf(request, "%*d %d %d %d %d " MAX_STRING, &cipher, &digest, &maclength, &compression, hexkey) != 5) { logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname); return false; } /* Convert the challenge from hexadecimal back to binary */ int inlen = hex2bin(hexkey, enckey, sizeof enckey); /* Check if the length of the meta key is all right */ if(inlen != len) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength"); return false; } /* Decrypt the meta key */ if(!rsa_private_decrypt(&myself->connection->rsa, enckey, len, key)) { logger(LOG_ERR, "Error during decryption of meta key for %s (%s)", c->name, c->hostname); return false; } ifdebug(SCARY_THINGS) { bin2hex(key, hexkey, len); logger(LOG_DEBUG, "Received random meta key (unencrypted): %s", hexkey); } /* Check and lookup cipher and digest algorithms */ if(!cipher_open_by_nid(&c->incipher, cipher) || !cipher_set_key_from_rsa(&c->incipher, key, len, false)) { logger(LOG_ERR, "Error during initialisation of cipher from %s (%s)", c->name, c->hostname); return false; } if(!digest_open_by_nid(&c->indigest, digest, -1)) { logger(LOG_ERR, "Error during initialisation of digest from %s (%s)", c->name, c->hostname); return false; } c->status.decryptin = true; c->allow_request = CHALLENGE; return send_challenge(c); } bool send_challenge(connection_t *c) { size_t len = c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&c->rsa); char buffer[len * 2 + 1]; if(!c->hischallenge) c->hischallenge = xrealloc(c->hischallenge, len); /* Copy random data to the buffer */ randomize(c->hischallenge, len); /* Convert to hex */ bin2hex(c->hischallenge, buffer, len); /* Send the challenge */ return send_request(c, "%d %s", CHALLENGE, buffer); } bool challenge_h(connection_t *c, char *request) { char buffer[MAX_STRING_SIZE]; size_t len = c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&myself->connection->rsa); size_t digestlen = digest_length(&c->indigest); char digest[digestlen]; if(sscanf(request, "%*d " MAX_STRING, buffer) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "CHALLENGE", c->name, c->hostname); return false; } /* Convert the challenge from hexadecimal back to binary */ int inlen = hex2bin(buffer, buffer, sizeof buffer); /* Check if the length of the challenge is all right */ if(inlen != len) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge length"); return false; } c->allow_request = CHAL_REPLY; /* Calculate the hash from the challenge we received */ digest_create(&c->indigest, buffer, len, digest); /* Convert the hash to a hexadecimal formatted string */ bin2hex(digest, buffer, digestlen); /* Send the reply */ return send_request(c, "%d %s", CHAL_REPLY, buffer); } bool chal_reply_h(connection_t *c, char *request) { char hishash[MAX_STRING_SIZE]; if(sscanf(request, "%*d " MAX_STRING, hishash) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "CHAL_REPLY", c->name, c->hostname); return false; } /* Convert the hash to binary format */ int inlen = hex2bin(hishash, hishash, sizeof hishash); /* Check if the length of the hash is all right */ if(inlen != digest_length(&c->outdigest)) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply length"); return false; } /* Verify the hash */ if(!digest_verify(&c->outdigest, c->hischallenge, c->protocol_minor >= 2 ? ECDH_SIZE : rsa_size(&c->rsa), hishash)) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply"); return false; } /* Identity has now been positively verified. Send an acknowledgement with the rest of the information needed. */ free(c->hischallenge); c->hischallenge = NULL; c->allow_request = ACK; return send_ack(c); } static bool send_upgrade(connection_t *c) { /* Special case when protocol_minor is 1: the other end is ECDSA capable, * but doesn't know our key yet. So send it now. */ char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa); if(!pubkey) return false; bool result = send_request(c, "%d %s", ACK, pubkey); free(pubkey); return result; } bool send_ack(connection_t *c) { if(c->protocol_minor == 1) return send_upgrade(c); /* ACK message contains rest of the information the other end needs to create node_t and edge_t structures. */ struct timeval now; bool choice; /* Estimate weight */ gettimeofday(&now, NULL); c->estimated_weight = (now.tv_sec - c->start.tv_sec) * 1000 + (now.tv_usec - c->start.tv_usec) / 1000; /* Check some options */ if((get_config_bool(lookup_config(c->config_tree, "IndirectData"), &choice) && choice) || myself->options & OPTION_INDIRECT) c->options |= OPTION_INDIRECT; if((get_config_bool(lookup_config(c->config_tree, "TCPOnly"), &choice) && choice) || myself->options & OPTION_TCPONLY) c->options |= OPTION_TCPONLY | OPTION_INDIRECT; if(myself->options & OPTION_PMTU_DISCOVERY) c->options |= OPTION_PMTU_DISCOVERY; choice = myself->options & OPTION_CLAMP_MSS; get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice); if(choice) c->options |= OPTION_CLAMP_MSS; get_config_int(lookup_config(c->config_tree, "Weight"), &c->estimated_weight); return send_request(c, "%d %s %d %x", ACK, myport, c->estimated_weight, c->options); } static void send_everything(connection_t *c) { splay_node_t *node, *node2; node_t *n; subnet_t *s; edge_t *e; /* Send all known subnets and edges */ if(tunnelserver) { for(node = myself->subnet_tree->head; node; node = node->next) { s = node->data; send_add_subnet(c, s); } return; } for(node = node_tree->head; node; node = node->next) { n = node->data; for(node2 = n->subnet_tree->head; node2; node2 = node2->next) { s = node2->data; send_add_subnet(c, s); } for(node2 = n->edge_tree->head; node2; node2 = node2->next) { e = node2->data; send_add_edge(c, e); } } } static bool upgrade_h(connection_t *c, char *request) { char pubkey[MAX_STRING_SIZE]; if(sscanf(request, "%*d " MAX_STRING, pubkey) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name, c->hostname); return false; } if(ecdsa_active(&c->ecdsa) || read_ecdsa_public_key(c)) { logger(LOG_INFO, "Already have ECDSA public key from %s (%s), not upgrading.", c->name, c->hostname); return false; } logger(LOG_INFO, "Got ECDSA public key from %s (%s), upgrading!", c->name, c->hostname); append_config_file(c->name, "ECDSAPublicKey", pubkey); c->allow_request = TERMREQ; return send_termreq(c); } bool ack_h(connection_t *c, char *request) { if(c->protocol_minor == 1) return upgrade_h(c, request); char hisport[MAX_STRING_SIZE]; char *hisaddress; int weight, mtu; uint32_t options; node_t *n; bool choice; if(sscanf(request, "%*d " MAX_STRING " %d %x", hisport, &weight, &options) != 3) { logger(LOG_ERR, "Got bad %s from %s (%s)", "ACK", c->name, c->hostname); return false; } /* Check if we already have a node_t for him */ n = lookup_node(c->name); if(!n) { n = new_node(); n->name = xstrdup(c->name); node_add(n); } else { if(n->connection) { /* Oh dear, we already have a connection to this node. */ ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Established a second connection with %s (%s), closing old connection", n->connection->name, n->connection->hostname); if(n->connection->outgoing) { if(c->outgoing) logger(LOG_WARNING, "Two outgoing connections to the same node!"); else c->outgoing = n->connection->outgoing; n->connection->outgoing = NULL; } terminate_connection(n->connection, false); /* Run graph algorithm to purge key and make sure up/down scripts are rerun with new IP addresses and stuff */ graph(); } } n->connection = c; c->node = n; if(!(c->options & options & OPTION_PMTU_DISCOVERY)) { c->options &= ~OPTION_PMTU_DISCOVERY; options &= ~OPTION_PMTU_DISCOVERY; } c->options |= options; if(get_config_int(lookup_config(c->config_tree, "PMTU"), &mtu) && mtu < n->mtu) n->mtu = mtu; if(get_config_int(lookup_config(config_tree, "PMTU"), &mtu) && mtu < n->mtu) n->mtu = mtu; if(get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice)) { if(choice) c->options |= OPTION_CLAMP_MSS; else c->options &= ~OPTION_CLAMP_MSS; } if(c->protocol_minor > 0) c->node->status.ecdh = true; /* Activate this connection */ c->allow_request = ALL; c->status.active = true; ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection with %s (%s) activated", c->name, c->hostname); /* Send him everything we know */ send_everything(c); /* Create an edge_t for this connection */ c->edge = new_edge(); c->edge->from = myself; c->edge->to = n; sockaddr2str(&c->address, &hisaddress, NULL); c->edge->address = str2sockaddr(hisaddress, hisport); free(hisaddress); c->edge->weight = (weight + c->estimated_weight) / 2; c->edge->connection = c; c->edge->options = c->options; edge_add(c->edge); /* Notify everyone of the new edge */ if(tunnelserver) send_add_edge(c, c->edge); else send_add_edge(broadcast, c->edge); /* Run MST and SSSP algorithms */ graph(); return true; }