tinc/src/protocol_auth.c

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2002-02-11 10:05:58 +00:00
/*
protocol_auth.c -- handle the meta-protocol, authentication
Copyright (C) 1999-2002 Ivo Timmermans <ivo@o2w.nl>,
2000-2002 Guus Sliepen <guus@sliepen.eu.org>
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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.
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$Id: protocol_auth.c,v 1.1.4.13 2002/09/04 14:17:28 guus Exp $
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*/
#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <stdio.h>
#include <stdarg.h>
#include <errno.h>
#include <utils.h>
#include <xalloc.h>
#include <avl_tree.h>
#include <openssl/sha.h>
#include <openssl/rand.h>
#include <openssl/evp.h>
#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"
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#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 %d %d %d %d %s", METAKEY,
c->outcipher?c->outcipher->nid:0, c->outdigest?c->outdigest->type:0,
c->outmaclength, c->outcompression, buffer);
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/* 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);
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c->status.encryptout = 1;
}
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cp
return x;
}
int metakey_h(connection_t *c)
{
char buffer[MAX_STRING_SIZE];
int cipher, digest, maclength, compression;
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int len;
cp
if(sscanf(c->buffer, "%*d %d %d %d %d "MAX_STRING, &cipher, &digest, &maclength, &compression, buffer) != 5)
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{
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
/* Check and lookup cipher and digest algorithms */
if(cipher)
{
c->incipher = EVP_get_cipherbynid(cipher);
if(!c->incipher)
{
syslog(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)
{
syslog(LOG_ERR, _("Node %s (%s) uses unknown digest!"), c->name, c->hostname);
return -1;
}
if(c->inmaclength > c->indigest->md_size || c->inmaclength < 0)
{
syslog(LOG_ERR, _("%s (%s) uses bogus MAC length!"), c->name, c->hostname);
return -1;
}
}
else
{
c->indigest = NULL;
}
c->incompression = compression;
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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[EVP_MAX_MD_SIZE*2+1];
EVP_MD_CTX ctx;
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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);
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/* Convert the hash to a hexadecimal formatted string */
bin2hex(hash,hash,c->indigest->md_size);
hash[c->indigest->md_size*2] = '\0';
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/* 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[EVP_MAX_MD_SIZE];
EVP_MD_CTX ctx;
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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) != c->outdigest->md_size*2)
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{
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, c->outdigest->md_size);
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/* 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);
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/* Verify the incoming hash with the calculated hash */
if(memcmp(hishash, myhash, c->outdigest->md_size))
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{
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. */
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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;
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x = send_request(c, "%d %s %d %lx", ACK, myport, c->estimated_weight, c->options);
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cp
return x;
}
void send_everything(connection_t *c)
{
avl_node_t *node, *node2;
node_t *n;
subnet_t *s;
edge_t *e;
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/* Send all known subnets */
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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)
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{
e = (edge_t *)node->data;
send_add_edge(c, e);
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}
}
int ack_h(connection_t *c)
{
char hisport[MAX_STRING_SIZE];
char *hisaddress, *dummy;
int weight;
long int options;
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node_t *n;
connection_t *other;
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avl_node_t *node;
cp
if(sscanf(c->buffer, "%*d "MAX_STRING" %d %lx", hisport, &weight, &options) != 3)
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{
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 */
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}
n->connection = c;
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c->node = n;
c->options |= options;
/* 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;
cp
edge_add(c->edge);
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/* 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 */
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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();
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cp
return 0;
}