/* protocol_auth.c -- handle the meta-protocol, authentication Copyright (C) 1999-2003 Ivo Timmermans , 2000-2003 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 1.1.4.24 2003/07/17 15:06:26 guus Exp $ */ #include "system.h" #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" 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) { logger(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)) { logger(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)) { logger(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) { logger(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); bla = read_connection_config(c); if(bla) { logger(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; 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_and_zero(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; 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, c->outkey, 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 -1; } /* 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) { EVP_EncryptInit(c->outctx, c->outcipher, c->outkey + len - c->outcipher->key_len, c->outkey + len - c->outcipher->key_len - c->outcipher->iv_len); c->status.encryptout = 1; } return x; } int metakey_h(connection_t *c) { char buffer[MAX_STRING_SIZE]; int cipher, digest, maclength, compression; int len; cp(); 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 -1; } 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 -1; } /* Allocate buffers for the meta key */ if(!c->inkey) c->inkey = xmalloc(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, buffer, c->inkey, myself->connection->rsa_key, RSA_NO_PADDING) != len) { /* See challenge() */ logger(LOG_ERR, _("Error during encryption of meta key for %s (%s)"), c->name, c->hostname); return -1; } 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 -1; } EVP_DecryptInit(c->inctx, c->incipher, c->inkey + len - c->incipher->key_len, c->inkey + len - c->incipher->key_len - c->incipher->iv_len); c->status.decryptin = 1; } 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 -1; } if(c->inmaclength > c->indigest->md_size || c->inmaclength < 0) { logger(LOG_ERR, _("%s (%s) uses bogus MAC length!"), c->name, c->hostname); return -1; } } else { c->indigest = NULL; } c->incompression = compression; c->allow_request = CHALLENGE; 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); /* Copy random data to the buffer */ RAND_bytes(c->hischallenge, len); /* Convert to hex */ bin2hex(c->hischallenge, buffer, len); buffer[len * 2] = '\0'; /* Send the challenge */ x = send_request(c, "%d %s", CHALLENGE, buffer); 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) { logger(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) { logger(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() */ return send_chal_reply(c); } int send_chal_reply(connection_t *c) { char hash[EVP_MAX_MD_SIZE * 2 + 1]; EVP_MD_CTX ctx; cp(); /* Calculate the hash from the challenge we received */ EVP_DigestInit(&ctx, c->indigest); EVP_DigestUpdate(&ctx, c->mychallenge, RSA_size(myself->connection->rsa_key)); EVP_DigestFinal(&ctx, hash, NULL); /* 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); } int chal_reply_h(connection_t *c) { char hishash[MAX_STRING_SIZE]; char myhash[EVP_MAX_MD_SIZE]; EVP_MD_CTX ctx; cp(); 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 -1; } /* 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 -1; } /* Convert the hash to binary format */ hex2bin(hishash, hishash, c->outdigest->md_size); /* Calculate the hash from the challenge we sent */ EVP_DigestInit(&ctx, c->outdigest); EVP_DigestUpdate(&ctx, c->hischallenge, RSA_size(c->rsa_key)); EVP_DigestFinal(&ctx, myhash, NULL); /* 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 -1; } /* Identity has now been positively verified. Send an acknowledgement with the rest of the information needed. */ c->allow_request = ACK; 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; 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; x = send_request(c, "%d %s %d %lx", ACK, myport, c->estimated_weight, c->options); return x; } 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 */ 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); } for(node2 = n->edge_tree->head; node2; node2 = node2->next) { e = (edge_t *) node2->data; send_add_edge(c, e); } } } int ack_h(connection_t *c) { char hisport[MAX_STRING_SIZE]; char *hisaddress, *dummy; int weight; long int options; node_t *n; cp(); if(sscanf(c->buffer, "%*d " MAX_STRING " %d %lx", hisport, &weight, &options) != 3) { logger(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. */ ifdebug(CONNECTIONS) logger(LOG_DEBUG, _("Established a second connection with %s (%s), closing old connection"), n->name, n->hostname); terminate_connection(n->connection, 0); /* 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; c->options |= options; /* Activate this connection */ c->allow_request = ALL; c->status.active = 1; 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(); cp(); 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 */ send_add_edge(broadcast, c->edge); /* Run MST and SSSP algorithms */ graph(); return 0; }