/* protocol_auth.c -- handle the meta-protocol, authentication Copyright (C) 1999-2005 Ivo Timmermans, 2000-2009 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 #include #include #include #include "avl_tree.h" #include "conf.h" #include "connection.h" #include "edge.h" #include "graph.h" #include "logger.h" #include "net.h" #include "netutl.h" #include "node.h" #include "protocol.h" #include "utils.h" #include "xalloc.h" bool send_id(connection_t *c) { return send_request(c, "%d %s %d", ID, myself->connection->name, myself->connection->protocol_version); } bool id_h(connection_t *c) { char name[MAX_STRING_SIZE]; if(sscanf(c->buffer, "%*d " MAX_STRING " %d", name, &c->protocol_version) != 2) { logger(LOG_ERR, "Got bad %s from %s (%s)", "ID", c->name, c->hostname); return false; } /* 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_version != myself->connection->protocol_version) { logger(LOG_ERR, "Peer %s (%s) uses incompatible version %d", c->name, c->hostname, c->protocol_version); return false; } if(bypass_security) { if(!c->config_tree) init_configuration(&c->config_tree); c->allow_request = ACK; return send_ack(c); } 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(!read_rsa_public_key(c)) { return false; } c->allow_request = METAKEY; return send_metakey(c); } bool send_metakey(connection_t *c) { char *buffer; int len; bool x; len = RSA_size(c->rsa_key); /* Allocate buffers for the meta key */ buffer = alloca(2 * len + 1); c->outkey = xrealloc(c->outkey, len); if(!c->outctx) c->outctx = xmalloc_and_zero(sizeof(*c->outctx)); /* Copy random data to the buffer */ RAND_pseudo_bytes((unsigned char *)c->outkey, 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. */ c->outkey[0] &= 0x7F; ifdebug(SCARY_THINGS) { bin2hex(c->outkey, buffer, len); buffer[len * 2] = '\0'; logger(LOG_DEBUG, "Generated random meta key (unencrypted): %s", buffer); } /* 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(len, (unsigned char *)c->outkey, (unsigned char *)buffer, c->rsa_key, RSA_NO_PADDING) != len) { 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(buffer, buffer, len); buffer[len * 2] = '\0'; /* Send the meta key */ x = send_request(c, "%d %d %d %d %d %s", METAKEY, c->outcipher ? c->outcipher->nid : 0, c->outdigest ? c->outdigest->type : 0, c->outmaclength, c->outcompression, buffer); /* Further outgoing requests are encrypted with the key we just generated */ if(c->outcipher) { if(!EVP_EncryptInit(c->outctx, c->outcipher, (unsigned char *)c->outkey + len - c->outcipher->key_len, (unsigned char *)c->outkey + len - c->outcipher->key_len - c->outcipher->iv_len)) { logger(LOG_ERR, "Error during initialisation of cipher for %s (%s): %s", c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL)); return false; } c->status.encryptout = true; } return x; } bool metakey_h(connection_t *c) { char buffer[MAX_STRING_SIZE]; int cipher, digest, maclength, compression; int len; if(sscanf(c->buffer, "%*d %d %d %d %d " MAX_STRING, &cipher, &digest, &maclength, &compression, buffer) != 5) { logger(LOG_ERR, "Got bad %s from %s (%s)", "METAKEY", c->name, c->hostname); return false; } len = RSA_size(myself->connection->rsa_key); /* Check if the length of the meta key is all right */ if(strlen(buffer) != len * 2) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong keylength"); return false; } /* Allocate buffers for the meta key */ c->inkey = xrealloc(c->inkey, len); if(!c->inctx) c->inctx = xmalloc_and_zero(sizeof(*c->inctx)); /* Convert the challenge from hexadecimal back to binary */ hex2bin(buffer, buffer, len); /* Decrypt the meta key */ if(RSA_private_decrypt(len, (unsigned char *)buffer, (unsigned char *)c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) { /* See challenge() */ logger(LOG_ERR, "Error during decryption of meta key for %s (%s)", c->name, c->hostname); return false; } ifdebug(SCARY_THINGS) { bin2hex(c->inkey, buffer, len); buffer[len * 2] = '\0'; logger(LOG_DEBUG, "Received random meta key (unencrypted): %s", buffer); } /* All incoming requests will now be encrypted. */ /* Check and lookup cipher and digest algorithms */ if(cipher) { c->incipher = EVP_get_cipherbynid(cipher); if(!c->incipher) { logger(LOG_ERR, "%s (%s) uses unknown cipher!", c->name, c->hostname); return false; } if(!EVP_DecryptInit(c->inctx, c->incipher, (unsigned char *)c->inkey + len - c->incipher->key_len, (unsigned char *)c->inkey + len - c->incipher->key_len - c->incipher->iv_len)) { logger(LOG_ERR, "Error during initialisation of cipher from %s (%s): %s", c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL)); return false; } c->status.decryptin = true; } else { c->incipher = NULL; } c->inmaclength = maclength; if(digest) { c->indigest = EVP_get_digestbynid(digest); if(!c->indigest) { logger(LOG_ERR, "Node %s (%s) uses unknown digest!", c->name, c->hostname); return false; } if(c->inmaclength > c->indigest->md_size || c->inmaclength < 0) { logger(LOG_ERR, "%s (%s) uses bogus MAC length!", c->name, c->hostname); return false; } } else { c->indigest = NULL; } c->incompression = compression; c->allow_request = CHALLENGE; return send_challenge(c); } bool send_challenge(connection_t *c) { char *buffer; int len; /* CHECKME: what is most reasonable value for len? */ len = RSA_size(c->rsa_key); /* Allocate buffers for the challenge */ buffer = alloca(2 * len + 1); c->hischallenge = xrealloc(c->hischallenge, len); /* Copy random data to the buffer */ RAND_pseudo_bytes((unsigned char *)c->hischallenge, len); /* Convert to hex */ bin2hex(c->hischallenge, buffer, len); buffer[len * 2] = '\0'; /* Send the challenge */ return send_request(c, "%d %s", CHALLENGE, buffer); } bool challenge_h(connection_t *c) { char buffer[MAX_STRING_SIZE]; int len; if(sscanf(c->buffer, "%*d " MAX_STRING, buffer) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "CHALLENGE", c->name, c->hostname); return false; } len = RSA_size(myself->connection->rsa_key); /* Check if the length of the challenge is all right */ if(strlen(buffer) != len * 2) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge length"); return false; } /* Allocate buffers for the challenge */ c->mychallenge = xrealloc(c->mychallenge, len); /* Convert the challenge from hexadecimal back to binary */ hex2bin(buffer, c->mychallenge, len); c->allow_request = CHAL_REPLY; /* Rest is done by send_chal_reply() */ return send_chal_reply(c); } bool send_chal_reply(connection_t *c) { char hash[EVP_MAX_MD_SIZE * 2 + 1]; EVP_MD_CTX ctx; /* Calculate the hash from the challenge we received */ if(!EVP_DigestInit(&ctx, c->indigest) || !EVP_DigestUpdate(&ctx, c->mychallenge, RSA_size(myself->connection->rsa_key)) || !EVP_DigestFinal(&ctx, (unsigned char *)hash, NULL)) { logger(LOG_ERR, "Error during calculation of response for %s (%s): %s", c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL)); return false; } /* Convert the hash to a hexadecimal formatted string */ bin2hex(hash, hash, c->indigest->md_size); hash[c->indigest->md_size * 2] = '\0'; /* Send the reply */ return send_request(c, "%d %s", CHAL_REPLY, hash); } bool chal_reply_h(connection_t *c) { char hishash[MAX_STRING_SIZE]; char myhash[EVP_MAX_MD_SIZE]; EVP_MD_CTX ctx; if(sscanf(c->buffer, "%*d " MAX_STRING, hishash) != 1) { logger(LOG_ERR, "Got bad %s from %s (%s)", "CHAL_REPLY", c->name, c->hostname); return false; } /* Check if the length of the hash is all right */ if(strlen(hishash) != c->outdigest->md_size * 2) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply length"); return false; } /* Convert the hash to binary format */ hex2bin(hishash, hishash, c->outdigest->md_size); /* Calculate the hash from the challenge we sent */ if(!EVP_DigestInit(&ctx, c->outdigest) || !EVP_DigestUpdate(&ctx, c->hischallenge, RSA_size(c->rsa_key)) || !EVP_DigestFinal(&ctx, (unsigned char *)myhash, NULL)) { logger(LOG_ERR, "Error during calculation of response from %s (%s): %s", c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL)); return false; } /* Verify the incoming hash with the calculated hash */ if(memcmp(hishash, myhash, c->outdigest->md_size)) { logger(LOG_ERR, "Possible intruder %s (%s): %s", c->name, c->hostname, "wrong challenge reply"); ifdebug(SCARY_THINGS) { bin2hex(myhash, hishash, SHA_DIGEST_LENGTH); hishash[SHA_DIGEST_LENGTH * 2] = '\0'; logger(LOG_DEBUG, "Expected challenge reply: %s", hishash); } return false; } /* Identity has now been positively verified. Send an acknowledgement with the rest of the information needed. */ c->allow_request = ACK; return send_ack(c); } bool send_ack(connection_t *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; 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) { avl_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); } } } bool ack_h(connection_t *c) { char hisport[MAX_STRING_SIZE]; char *hisaddress, *dummy; int weight, mtu; uint32_t options; node_t *n; if(sscanf(c->buffer, "%*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->name, n->hostname); 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(myself->connection->config_tree, "PMTU"), &mtu) && mtu < n->mtu) n->mtu = mtu; /* 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, &dummy); c->edge->address = str2sockaddr(hisaddress, hisport); free(hisaddress); free(dummy); 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; }