/* protocol_auth.c -- handle the meta-protocol, authentication Copyright (C) 1999-2002 Ivo Timmermans , 2000-2002 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., 675 Mass Ave, Cambridge, MA 02139, USA. $Id: protocol_auth.c,v 1.1.4.2 2002/02/18 16:25:16 guus Exp $ */ #include "config.h" #include #include #include #include #include #include #include #include #include #include #include #include #ifndef HAVE_RAND_PSEUDO_BYTES #define RAND_pseudo_bytes RAND_bytes #endif #include "conf.h" #include "net.h" #include "netutl.h" #include "protocol.h" #include "meta.h" #include "connection.h" #include "node.h" #include "edge.h" #include "graph.h" #include "system.h" int send_id(connection_t *c) { cp return send_request(c, "%d %s %d", ID, myself->connection->name, myself->connection->protocol_version); } int id_h(connection_t *c) { char name[MAX_STRING_SIZE]; int bla; cp if(sscanf(c->buffer, "%*d "MAX_STRING" %d", name, &c->protocol_version) != 2) { syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "ID", c->name, c->hostname); return -1; } /* Check if identity is a valid name */ if(check_id(name)) { syslog(LOG_ERR, _("Got bad %s from %s (%s): %s"), "ID", c->name, c->hostname, "invalid name"); return -1; } /* If we set c->name in advance, make sure we are connected to the right host */ if(c->name) { if(strcmp(c->name, name)) { syslog(LOG_ERR, _("Peer %s is %s instead of %s"), c->hostname, name, c->name); return -1; } } else c->name = xstrdup(name); /* Check if version matches */ if(c->protocol_version != myself->connection->protocol_version) { syslog(LOG_ERR, _("Peer %s (%s) uses incompatible version %d"), c->name, c->hostname, c->protocol_version); return -1; } 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((bla = read_connection_config(c))) { syslog(LOG_ERR, _("Peer %s had unknown identity (%s)"), c->hostname, c->name); return -1; } } if(read_rsa_public_key(c)) { return -1; } /* Check some options */ if((get_config_bool(lookup_config(c->config_tree, "IndirectData"), &bla) && bla) || myself->options & OPTION_INDIRECT) c->options |= OPTION_INDIRECT; if((get_config_bool(lookup_config(c->config_tree, "TCPOnly"), &bla) && bla) || myself->options & OPTION_TCPONLY) c->options |= OPTION_TCPONLY | OPTION_INDIRECT; c->allow_request = METAKEY; cp return send_metakey(c); } int send_metakey(connection_t *c) { char buffer[MAX_STRING_SIZE]; int len, x; cp len = RSA_size(c->rsa_key); /* Allocate buffers for the meta key */ if(!c->outkey) c->outkey = xmalloc(len); if(!c->outctx) c->outctx = xmalloc(sizeof(*c->outctx)); cp /* Copy random data to the buffer */ RAND_bytes(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; if(debug_lvl >= DEBUG_SCARY_THINGS) { bin2hex(c->outkey, buffer, len); buffer[len*2] = '\0'; syslog(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, c->outkey, buffer, c->rsa_key, RSA_NO_PADDING) != len) { syslog(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), c->name, c->hostname); return -1; } cp /* 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 %s", METAKEY, buffer); /* Further outgoing requests are encrypted with the key we just generated */ EVP_EncryptInit(c->outctx, EVP_bf_cfb(), c->outkey + len - EVP_bf_cfb()->key_len, c->outkey + len - EVP_bf_cfb()->key_len - EVP_bf_cfb()->iv_len); c->status.encryptout = 1; cp return x; } int metakey_h(connection_t *c) { char buffer[MAX_STRING_SIZE]; int len; cp if(sscanf(c->buffer, "%*d "MAX_STRING, buffer) != 1) { syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "METAKEY", c->name, c->hostname); return -1; } cp len = RSA_size(myself->connection->rsa_key); /* Check if the length of the meta key is all right */ if(strlen(buffer) != len*2) { syslog(LOG_ERR, _("Possible intruder %s (%s): %s"), c->name, c->hostname, "wrong keylength"); return -1; } /* Allocate buffers for the meta key */ cp if(!c->inkey) c->inkey = xmalloc(len); if(!c->inctx) c->inctx = xmalloc(sizeof(*c->inctx)); /* Convert the challenge from hexadecimal back to binary */ cp hex2bin(buffer,buffer,len); /* Decrypt the meta key */ cp if(RSA_private_decrypt(len, buffer, c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) /* See challenge() */ { syslog(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), c->name, c->hostname); return -1; } if(debug_lvl >= DEBUG_SCARY_THINGS) { bin2hex(c->inkey, buffer, len); buffer[len*2] = '\0'; syslog(LOG_DEBUG, _("Received random meta key (unencrypted): %s"), buffer); } /* All incoming requests will now be encrypted. */ cp EVP_DecryptInit(c->inctx, EVP_bf_cfb(), c->inkey + len - EVP_bf_cfb()->key_len, c->inkey + len - EVP_bf_cfb()->key_len - EVP_bf_cfb()->iv_len); c->status.decryptin = 1; c->allow_request = CHALLENGE; cp return send_challenge(c); } int send_challenge(connection_t *c) { char buffer[MAX_STRING_SIZE]; int len, x; cp /* CHECKME: what is most reasonable value for len? */ len = RSA_size(c->rsa_key); /* Allocate buffers for the challenge */ if(!c->hischallenge) c->hischallenge = xmalloc(len); cp /* Copy random data to the buffer */ RAND_bytes(c->hischallenge, len); cp /* Convert to hex */ bin2hex(c->hischallenge, buffer, len); buffer[len*2] = '\0'; cp /* Send the challenge */ x = send_request(c, "%d %s", CHALLENGE, buffer); cp return x; } int challenge_h(connection_t *c) { char buffer[MAX_STRING_SIZE]; int len; cp if(sscanf(c->buffer, "%*d "MAX_STRING, buffer) != 1) { syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "CHALLENGE", c->name, c->hostname); return -1; } len = RSA_size(myself->connection->rsa_key); /* Check if the length of the challenge is all right */ if(strlen(buffer) != len*2) { syslog(LOG_ERR, _("Possible intruder %s (%s): %s"), c->name, c->hostname, "wrong challenge length"); return -1; } /* Allocate buffers for the challenge */ if(!c->mychallenge) c->mychallenge = xmalloc(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() */ cp return send_chal_reply(c); } int send_chal_reply(connection_t *c) { char hash[SHA_DIGEST_LENGTH*2+1]; cp /* Calculate the hash from the challenge we received */ SHA1(c->mychallenge, RSA_size(myself->connection->rsa_key), hash); /* Convert the hash to a hexadecimal formatted string */ bin2hex(hash,hash,SHA_DIGEST_LENGTH); hash[SHA_DIGEST_LENGTH*2] = '\0'; /* Send the reply */ cp return send_request(c, "%d %s", CHAL_REPLY, hash); } int chal_reply_h(connection_t *c) { char hishash[MAX_STRING_SIZE]; char myhash[SHA_DIGEST_LENGTH]; cp if(sscanf(c->buffer, "%*d "MAX_STRING, hishash) != 1) { syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "CHAL_REPLY", c->name, c->hostname); return -1; } /* Check if the length of the hash is all right */ if(strlen(hishash) != SHA_DIGEST_LENGTH*2) { syslog(LOG_ERR, _("Possible intruder %s (%s): %s"), c->name, c->hostname, _("wrong challenge reply length")); return -1; } /* Convert the hash to binary format */ hex2bin(hishash, hishash, SHA_DIGEST_LENGTH); /* Calculate the hash from the challenge we sent */ SHA1(c->hischallenge, RSA_size(c->rsa_key), myhash); /* Verify the incoming hash with the calculated hash */ if(memcmp(hishash, myhash, SHA_DIGEST_LENGTH)) { syslog(LOG_ERR, _("Possible intruder %s (%s): %s"), c->name, c->hostname, _("wrong challenge reply")); if(debug_lvl >= DEBUG_SCARY_THINGS) { bin2hex(myhash, hishash, SHA_DIGEST_LENGTH); hishash[SHA_DIGEST_LENGTH*2] = '\0'; syslog(LOG_DEBUG, _("Expected challenge reply: %s"), hishash); } return -1; } /* Identity has now been positively verified. Send an acknowledgement with the rest of the information needed. */ c->allow_request = ACK; cp return send_ack(c); } int send_ack(connection_t *c) { /* ACK message contains rest of the information the other end needs to create node_t and edge_t structures. */ int x; char *address, *port; struct timeval now; cp /* Estimate weight */ gettimeofday(&now, NULL); c->estimated_weight = (now.tv_sec - c->start.tv_sec) * 1000 + (now.tv_usec - c->start.tv_usec) / 1000; sockaddr2str(&c->address, &address, &port); x = send_request(c, "%d %s %s %s %d %d", ACK, myport, address, port, c->estimated_weight, c->options); free(address); free(port); cp return x; } void send_everything(connection_t *c) { avl_node_t *node, *node2; node_t *n; subnet_t *s; edge_t *e; /* Send all known subnets */ for(node = node_tree->head; node; node = node->next) { n = (node_t *)node->data; for(node2 = n->subnet_tree->head; node2; node2 = node2->next) { s = (subnet_t *)node2->data; send_add_subnet(c, s); } } /* Send all known edges */ for(node = edge_tree->head; node; node = node->next) { e = (edge_t *)node->data; if(e == c->edge) continue; send_add_edge(c, e); } } int ack_h(connection_t *c) { char address[MAX_STRING_SIZE]; char port[MAX_STRING_SIZE]; char hisport[MAX_STRING_SIZE]; char *hisaddress, *dummy; int weight; int options; node_t *n; connection_t *other; avl_node_t *node; cp if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d", hisport, address, port, &weight, &options) != 5) { syslog(LOG_ERR, _("Got bad %s from %s (%s)"), "ACK", c->name, c->hostname); return -1; } /* 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. */ if(debug_lvl >= DEBUG_CONNECTIONS) syslog(LOG_DEBUG, _("Established a second connection with %s (%s), closing old connection"), n->name, n->hostname); terminate_connection(n->connection, 0); } /* FIXME: check if information in existing node matches that of the other end of this connection */ } n->connection = c; c->node = n; c->options |= options; /* Create an edge_t for this connection */ c->edge = new_edge(); cp c->edge->from.node = myself; c->edge->from.tcpaddress = str2sockaddr(address, port); c->edge->from.udpaddress = str2sockaddr(address, myport); c->edge->to.node = n; c->edge->to.tcpaddress = c->address; sockaddr2str(&c->address, &hisaddress, &dummy); c->edge->to.udpaddress = str2sockaddr(hisaddress, hisport); free(hisaddress); free(dummy); c->edge->weight = (weight + c->estimated_weight) / 2; c->edge->connection = c; c->edge->options = c->options; cp edge_add(c->edge); /* Activate this connection */ c->allow_request = ALL; c->status.active = 1; if(debug_lvl >= DEBUG_CONNECTIONS) syslog(LOG_NOTICE, _("Connection with %s (%s) activated"), c->name, c->hostname); cp /* Send him everything we know */ send_everything(c); /* Notify others of this connection */ for(node = connection_tree->head; node; node = node->next) { other = (connection_t *)node->data; if(other->status.active && other != c) send_add_edge(other, c->edge); } /* Run MST and SSSP algorithms */ graph(); /* Succesful connection, reset timeout if this is an outgoing connection. */ if(c->outgoing) c->outgoing->timeout = 0; cp return 0; }