Check RAND_bytes() return value, fail when getting random fails.
[tinc] / src / protocol_auth.c
index 24f591a..87ba30a 100644 (file)
@@ -1,7 +1,7 @@
 /*
     protocol_auth.c -- handle the meta-protocol, authentication
     Copyright (C) 1999-2005 Ivo Timmermans,
-                  2000-2009 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2013 Guus Sliepen <guus@tinc-vpn.org>
 
     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
@@ -31,6 +31,7 @@
 #include "edge.h"
 #include "graph.h"
 #include "logger.h"
+#include "meta.h"
 #include "net.h"
 #include "netutl.h"
 #include "node.h"
 #include "utils.h"
 #include "xalloc.h"
 
+static bool send_proxyrequest(connection_t *c) {
+       switch(proxytype) {
+               case PROXY_HTTP: {
+                       char *host;
+                       char *port;
+
+                       sockaddr2str(&c->address, &host, &port);
+                       send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
+                       free(host);
+                       free(port);
+                       return true;
+               }
+               case PROXY_SOCKS4: {
+                       if(c->address.sa.sa_family != AF_INET) {
+                               logger(LOG_ERR, "Cannot connect to an IPv6 host through a SOCKS 4 proxy!");
+                               return false;
+                       }
+                       char s4req[9 + (proxyuser ? strlen(proxyuser) : 0)];
+                       s4req[0] = 4;
+                       s4req[1] = 1;
+                       memcpy(s4req + 2, &c->address.in.sin_port, 2);
+                       memcpy(s4req + 4, &c->address.in.sin_addr, 4);
+                       if(proxyuser)
+                               strcpy(s4req + 8, proxyuser);
+                       s4req[sizeof s4req - 1] = 0;
+                       c->tcplen = 8;
+                       return send_meta(c, s4req, sizeof s4req);
+               }
+               case PROXY_SOCKS5: {
+                       int len = 3 + 6 + (c->address.sa.sa_family == AF_INET ? 4 : 16);
+                       c->tcplen = 2;
+                       if(proxypass)
+                               len += 3 + strlen(proxyuser) + strlen(proxypass);
+                       char s5req[len];
+                       int i = 0;
+                       s5req[i++] = 5;
+                       s5req[i++] = 1;
+                       if(proxypass) {
+                               s5req[i++] = 2;
+                               s5req[i++] = 1;
+                               s5req[i++] = strlen(proxyuser);
+                               strcpy(s5req + i, proxyuser);
+                               i += strlen(proxyuser);
+                               s5req[i++] = strlen(proxypass);
+                               strcpy(s5req + i, proxypass);
+                               i += strlen(proxypass);
+                               c->tcplen += 2;
+                       } else {
+                               s5req[i++] = 0;
+                       }
+                       s5req[i++] = 5;
+                       s5req[i++] = 1;
+                       s5req[i++] = 0;
+                       if(c->address.sa.sa_family == AF_INET) {
+                               s5req[i++] = 1;
+                               memcpy(s5req + i, &c->address.in.sin_addr, 4);
+                               i += 4;
+                               memcpy(s5req + i, &c->address.in.sin_port, 2);
+                               i += 2;
+                               c->tcplen += 10;
+                       } else if(c->address.sa.sa_family == AF_INET6) {
+                               s5req[i++] = 3;
+                               memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
+                               i += 16;
+                               memcpy(s5req + i, &c->address.in6.sin6_port, 2);
+                               i += 2;
+                               c->tcplen += 22;
+                       } else {
+                               logger(LOG_ERR, "Address family %hx not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
+                               return false;
+                       }
+                       if(i > len)
+                               abort();
+                       return send_meta(c, s5req, sizeof s5req);
+               }
+               case PROXY_SOCKS4A:
+                       logger(LOG_ERR, "Proxy type not implemented yet");
+                       return false;
+               case PROXY_EXEC:
+                       return true;
+               default:
+                       logger(LOG_ERR, "Unknown proxy type");
+                       return false;
+       }
+}
+
 bool send_id(connection_t *c) {
+       if(proxytype && c->outgoing)
+               if(!send_proxyrequest(c))
+                       return false;
+
        return send_request(c, "%d %s %d", ID, myself->connection->name,
                                                myself->connection->protocol_version);
 }
@@ -109,15 +200,13 @@ bool id_h(connection_t *c) {
 }
 
 bool send_metakey(connection_t *c) {
-       char *buffer;
-       int len;
        bool x;
 
-       len = RSA_size(c->rsa_key);
+       int len = RSA_size(c->rsa_key);
 
        /* Allocate buffers for the meta key */
 
-       buffer = alloca(2 * len + 1);
+       char buffer[2 * len + 1];
        
        c->outkey = xrealloc(c->outkey, len);
 
@@ -126,7 +215,12 @@ bool send_metakey(connection_t *c) {
 
        /* Copy random data to the buffer */
 
-       RAND_pseudo_bytes((unsigned char *)c->outkey, len);
+       if (1 != RAND_bytes((unsigned char *)c->outkey, len)) {
+               int err = ERR_get_error();
+               logger(LOG_ERR, "Failed to generate meta key (%s)", "SEND_METAKEY", ERR_error_string(err, NULL));
+               return false;
+       }
+
 
        /* 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:
@@ -155,8 +249,8 @@ bool send_metakey(connection_t *c) {
         */
 
        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);
+               logger(LOG_ERR, "Error during encryption of meta key for %s (%s): %s",
+                          c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
                return false;
        }
 
@@ -219,13 +313,16 @@ bool metakey_h(connection_t *c) {
 
        /* Convert the challenge from hexadecimal back to binary */
 
-       hex2bin(buffer, buffer, len);
+       if(!hex2bin(buffer, buffer, len)) {
+               logger(LOG_ERR, "Got bad %s from %s(%s): %s", "METAKEY", c->name, c->hostname, "invalid key");
+               return false;
+       }
 
        /* 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);
+               logger(LOG_ERR, "Error during decryption of meta key for %s (%s): %s",
+                          c->name, c->hostname, ERR_error_string(ERR_get_error(), NULL));
                return false;
        }
 
@@ -287,22 +384,23 @@ bool metakey_h(connection_t *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);
+       int len = RSA_size(c->rsa_key);
 
        /* Allocate buffers for the challenge */
 
-       buffer = alloca(2 * len + 1);
+       char buffer[2 * len + 1];
 
        c->hischallenge = xrealloc(c->hischallenge, len);
 
        /* Copy random data to the buffer */
 
-       RAND_pseudo_bytes((unsigned char *)c->hischallenge, len);
+       if (1 != RAND_bytes((unsigned char *)c->hischallenge, len)) {
+               int err = ERR_get_error();
+               logger(LOG_ERR, "Failed to generate challenge (%s)", "SEND_CHALLENGE", ERR_error_string(err, NULL));
+               return false; // Do not send predictable challenges, let connection attempt fail.
+       }
 
        /* Convert to hex */
 
@@ -340,7 +438,10 @@ bool challenge_h(connection_t *c) {
 
        /* Convert the challenge from hexadecimal back to binary */
 
-       hex2bin(buffer, c->mychallenge, len);
+       if(!hex2bin(buffer, c->mychallenge, len)) {
+               logger(LOG_ERR, "Got bad %s from %s(%s): %s", "CHALLENGE", c->name, c->hostname, "invalid challenge");
+               return false;
+       }
 
        c->allow_request = CHAL_REPLY;
 
@@ -394,7 +495,10 @@ bool chal_reply_h(connection_t *c) {
 
        /* Convert the hash to binary format */
 
-       hex2bin(hishash, hishash, c->outdigest->md_size);
+       if(!hex2bin(hishash, hishash, c->outdigest->md_size)) {
+               logger(LOG_ERR, "Got bad %s from %s(%s): %s", "CHAL_REPLY", c->name, c->hostname, "invalid hash");
+               return false;
+       }
 
        /* Calculate the hash from the challenge we sent */
 
@@ -453,9 +557,14 @@ bool send_ack(connection_t *c) {
        if(myself->options & OPTION_PMTU_DISCOVERY)
                c->options |= OPTION_PMTU_DISCOVERY;
 
+       choice = myself->options & OPTION_CLAMP_MSS;
+       get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice);
+       if(choice)
+               c->options |= OPTION_CLAMP_MSS;
+
        get_config_int(lookup_config(c->config_tree, "Weight"), &c->estimated_weight);
 
-       return send_request(c, "%d %s %d %lx", ACK, myport, c->estimated_weight, c->options);
+       return send_request(c, "%d %s %d %x", ACK, myport, c->estimated_weight, c->options);
 }
 
 static void send_everything(connection_t *c) {
@@ -492,12 +601,13 @@ static void send_everything(connection_t *c) {
 
 bool ack_h(connection_t *c) {
        char hisport[MAX_STRING_SIZE];
-       char *hisaddress, *dummy;
+       char *hisaddress;
        int weight, mtu;
-       long int options;
+       uint32_t options;
        node_t *n;
+       bool choice;
 
-       if(sscanf(c->buffer, "%*d " MAX_STRING " %d %lx", hisport, &weight, &options) != 3) {
+       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;
@@ -533,9 +643,16 @@ bool ack_h(connection_t *c) {
        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)
+       if(get_config_int(lookup_config(config_tree, "PMTU"), &mtu) && mtu < n->mtu)
                n->mtu = mtu;
 
+       if(get_config_bool(lookup_config(c->config_tree, "ClampMSS"), &choice)) {
+               if(choice)
+                       c->options |= OPTION_CLAMP_MSS;
+               else
+                       c->options &= ~OPTION_CLAMP_MSS;
+       }
+
        /* Activate this connection */
 
        c->allow_request = ALL;
@@ -553,10 +670,9 @@ bool ack_h(connection_t *c) {
        c->edge = new_edge();
        c->edge->from = myself;
        c->edge->to = n;
-       sockaddr2str(&c->address, &hisaddress, &dummy);
+       sockaddr2str(&c->address, &hisaddress, NULL);
        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;
@@ -568,7 +684,7 @@ bool ack_h(connection_t *c) {
        if(tunnelserver)
                send_add_edge(c, c->edge);
        else
-               send_add_edge(broadcast, c->edge);
+               send_add_edge(everyone, c->edge);
 
        /* Run MST and SSSP algorithms */