X-Git-Url: https://www.tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=src%2Fprotocol.c;h=ef6018020cd066f77d31801fefb459771b9aef09;hp=a193933b94c0cb68819184aee32c8a2fe4f8caf2;hb=1e2bdc2b6d28c76c63fc9fd36169b90fa0994388;hpb=4fa12eb85d72f039df5004abc201f01f5573c2e4 diff --git a/src/protocol.c b/src/protocol.c index a193933b..ef601802 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 1.28.4.83 2001/02/27 16:37:28 guus Exp $ + $Id: protocol.c,v 1.28.4.98 2001/07/04 08:41:36 guus Exp $ */ #include "config.h" @@ -40,25 +40,14 @@ #include -#ifdef HAVE_OPENSSL_SHA_H -# include -#else -# include -#endif - -#ifdef HAVE_OPENSSL_RAND_H -# include -#else -# include -#endif +#include +#include +#include -#ifdef HAVE_OPENSSL_EVP_H -# include -#else -# include +#ifndef HAVE_RAND_PSEUDO_BYTES +#define RAND_pseudo_bytes RAND_bytes #endif - #include "conf.h" #include "net.h" #include "netutl.h" @@ -68,6 +57,8 @@ #include "system.h" +int mykeyused = 0; + int check_id(char *id) { int i; @@ -104,11 +95,15 @@ 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 +111,31 @@ 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)) @@ -156,34 +162,8 @@ 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) { @@ -223,6 +203,9 @@ cp /* Copy string to cl */ + if(cl->name) + free(cl->name); + cl->name = xstrdup(name); /* Load information about peer */ @@ -233,22 +216,22 @@ cp return -1; } - /* First check if the host we connected to is already in our + /* First check if the host is already in our connection list. If so, we are probably making a loop, which is not desirable. */ - if(cl->status.outgoing) + if((old = lookup_id(cl->name))) { - if((old = lookup_id(cl->name))) + if(debug_lvl >= DEBUG_CONNECTIONS) + syslog(LOG_NOTICE, _("%s (%s) is already in our connection list"), cl->name, cl->hostname); + if(cl->status.outgoing) { - if(debug_lvl >= DEBUG_CONNECTIONS) - syslog(LOG_NOTICE, _("Uplink %s (%s) is already in our connection list"), cl->name, cl->hostname); cl->status.outgoing = 0; old->status.outgoing = 1; - terminate_connection(cl); - return 0; } + terminate_connection(cl); + return 0; } /* Now we can add the name to the id tree */ @@ -259,8 +242,14 @@ cp node = avl_unlink(connection_tree, cl); cl->port = port; - avl_insert_node(connection_tree, node); - + if(!avl_insert_node(connection_tree, node)) + { + old = avl_search_node(connection_tree, node)->data; + syslog(LOG_ERR, _("%s is listening on %s:%hd, which is already in use by %s!"), + cl->name, cl->hostname, cl->port, old->name); + return -1; + } + /* Read in the public key, so that we can send a metakey */ if(read_rsa_public_key(cl)) @@ -303,6 +292,8 @@ cp if(debug_lvl >= DEBUG_CONNECTIONS) syslog(LOG_NOTICE, _("Connection with %s (%s) activated"), cl->name, cl->hostname); + if(cl->status.outgoing) + seconds_till_retry = 5; /* Reset retry timeout */ cp /* Check some options */ @@ -325,6 +316,7 @@ cp 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) @@ -521,7 +513,17 @@ cp RAND_bytes(cl->cipher_outkey, len); - cl->cipher_outkey[0] &= 0x0F; /* Make sure that the random data is smaller than the modulus of the RSA key */ + /* 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) { @@ -530,9 +532,14 @@ cp syslog(LOG_DEBUG, _("Generated random meta key (unencrypted): %s"), buffer); } - /* Encrypt the random data */ + /* 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, 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 */ + 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); @@ -629,7 +636,7 @@ 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; @@ -795,7 +802,7 @@ 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 @@ -889,7 +896,7 @@ 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 @@ -899,7 +906,7 @@ cp 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; @@ -1044,11 +1051,15 @@ cp int send_ping(connection_t *cl) { + char salt[SALTLEN*2+1]; cp cl->status.pinged = 1; cl->last_ping_time = time(NULL); + RAND_pseudo_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) @@ -1059,8 +1070,13 @@ cp int send_pong(connection_t *cl) { + char salt[SALTLEN*2+1]; +cp + RAND_pseudo_bytes(salt, SALTLEN); + bin2hex(salt, salt, SALTLEN); + salt[SALTLEN*2] = '\0'; cp - return send_request(cl, "%d", PONG); + return send_request(cl, "%d %s", PONG, salt); } int pong_h(connection_t *cl) @@ -1078,6 +1094,13 @@ int send_key_changed(connection_t *from, connection_t *cl) connection_t *p; avl_node_t *node; cp + /* Only send this message if some other daemon requested our key previously. + This reduces unnecessary key_changed broadcasts. + */ + + if(from==myself && !mykeyused) + return 0; + for(node = connection_tree->head; node; node = node->next) { p = (connection_t *)node->data; @@ -1111,7 +1134,8 @@ 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; } @@ -1146,11 +1170,12 @@ 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 { @@ -1249,54 +1274,32 @@ 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. */ - - 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); + /* Set reqlen to len, this will tell receive_meta() that a tcppacket is coming. */ - return -1; - } - - todo -= x; - p += x; - } - - return receive_packet(cl, &packet); + cl->tcplen = len; +cp + return 0; } /* Jumptable for the request handlers */