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vtun
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Implement a key exchange mechanism

This commit is contained in:
Frank Denis 2015-10-17 02:10:35 +02:00
parent 1159f54fe4
commit df8bacead5
8 changed files with 422 additions and 363 deletions
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11
README.md
View File

@ -8,10 +8,11 @@ compiled until version 1.0.4 is out).
* Unauthenticated encryption schemes were replaced with aesni and
pclmulqdq-accelerated AES256-GCM.
* The static, shared key was replaced by an ephemeral keys exchange with
Curve25519. The PSK is now only used to sign ephemeral public keys and
parameters.
* Protection against replay attacks was added.
* More secure key derivation and initial handshake.
* Passwords are not kept in memory.
* Guarded memory allocations for secrets.
* Passwords are not kept in memory, guarded memory allocations are
used for secrets.

718
auth.c
View File

@ -1,28 +1,23 @@
/*
VTun - Virtual Tunnel over TCP/IP network.
Copyright (C) 1998-2008 Maxim Krasnyansky <max_mk@yahoo.com>
VTun has been derived from VPPP package by Maxim Krasnyansky.
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.
*/
/*
* $Id: auth.c,v 1.9.2.5 2013/07/07 19:54:20 mtbishop Exp $
*/
/*
* Challenge based authentication.
* Thanx to Chris Todd<christ@insynq.com> for the good idea.
* Key exchange
*
* Client <-> Server
*
* -> "CKEY " || host || " " || ts || Cpk || Hk(ts || Cpk)
* <- "SKEY " || Spk || Hk(Spk || Hk(ts || Cpk))
* -> "CACK " || Hk("CACK" || Hk(Spk || Hk(ts || Cpk)))
* <- "FLAGS " || flags || " " || Hk(flags || Hk("CACK" || Hk(Spk || Hk(ts || Cpk))))
*
* session_key = Hk(DH)
*
* ts: current timestamp, 4 big-endian bytes
* (Cpk, Csk): client public/secret ephemeral key pair
* (Spk, Ssk): server public/secret ephemeral key pair
* Hk: keyed hash function, key derived from the PSK
*
* DH function: Curve25519
* Keyed hash function: Blake2b
* KDF: Scrypt
*/
#include "config.h"
@ -51,60 +46,38 @@
#include <arpa/inet.h>
#endif
#include <sodium.h>
#include "vtun.h"
#include "lib.h"
#include "lock.h"
#include "auth.h"
/* Encryption and Decryption of the challenge key */
#include <sodium.h>
static int derive_key(struct vtun_host *host)
{
unsigned char salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
int ret = -1;
size_t bin_len;
unsigned char salt[crypto_pwhash_scryptsalsa208sha256_SALTBYTES];
int ret = -1;
size_t bin_len;
if (host->key != NULL) {
return 0;
}
if ((host->key = sodium_malloc(HOST_KEYBYTES)) == NULL) {
return -1;
}
if (host->akey != NULL) {
return 0;
}
if ((host->akey = sodium_malloc(crypto_generichash_KEYBYTES)) == NULL) {
return -1;
}
memset(salt, 0xd1, sizeof salt);
if (crypto_pwhash_scryptsalsa208sha256(host->akey, HOST_KEYBYTES,
host->passwd, strlen(host->passwd), salt,
crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE,
crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) == 0) {
ret = 0;
}
sodium_memzero(host->passwd, strlen(host->passwd));
free(host->passwd);
host->passwd = NULL;
vtun_syslog(LOG_DEBUG, "Key ready for host [%s]", host->host);
sodium_hex2bin(host->key, HOST_KEYBYTES, host->passwd,
strlen(host->passwd), "", &bin_len, NULL);
if (bin_len == HOST_KEYBYTES) {
vtun_syslog(LOG_ERR,"supplied password is long enough to be the secret");
return 0;
}
memset(salt, 0xd1, sizeof salt);
if (crypto_pwhash_scryptsalsa208sha256
(host->key, HOST_KEYBYTES, host->passwd, strlen(host->passwd), salt,
crypto_pwhash_scryptsalsa208sha256_OPSLIMIT_INTERACTIVE,
crypto_pwhash_scryptsalsa208sha256_MEMLIMIT_INTERACTIVE) == 0) {
ret = 0;
}
sodium_memzero(host->passwd, strlen(host->passwd));
free(host->passwd);
host->passwd = NULL;
vtun_syslog(LOG_DEBUG,"Key ready for host %s.", host->host);
return ret;
}
static void gen_chal(char *chal)
{
randombytes_buf((unsigned char *) chal, VTUN_CHAL_SIZE);
}
static void auth_chal(char *chal, const struct vtun_host *host)
{
crypto_generichash((unsigned char *) chal, VTUN_CHAL_SIZE,
(const unsigned char *) chal,
VTUN_CHAL_SIZE, host->key, HOST_KEYBYTES);
return ret;
}
/*
@ -115,296 +88,389 @@ static void auth_chal(char *chal, const struct vtun_host *host)
static char *bf2cf(struct vtun_host *host)
{
static char str[20], *ptr = str;
static char str[20], * ptr = str;
*(ptr++) = '<';
*(ptr++) = '<';
switch( host->flags & VTUN_PROT_MASK ){
case VTUN_TCP:
*(ptr++) = 'T';
break;
switch (host->flags & VTUN_PROT_MASK) {
case VTUN_TCP:
*(ptr++) = 'T';
break;
case VTUN_UDP:
*(ptr++) = 'U';
break;
}
case VTUN_UDP:
*(ptr++) = 'U';
break;
}
switch (host->flags & VTUN_TYPE_MASK) {
case VTUN_TTY:
*(ptr++) = 't';
break;
case VTUN_PIPE:
*(ptr++) = 'p';
break;
case VTUN_ETHER:
*(ptr++) = 'e';
break;
case VTUN_TUN:
*(ptr++) = 'u';
break;
}
if ((host->flags & VTUN_SHAPE) /* && host->spd_in */)
ptr += sprintf(ptr, "S%d", host->spd_in);
switch( host->flags & VTUN_TYPE_MASK ){
case VTUN_TTY:
*(ptr++) = 't';
break;
if (host->flags & VTUN_ZLIB)
ptr += sprintf(ptr, "C%d", host->zlevel);
case VTUN_PIPE:
*(ptr++) = 'p';
break;
if (host->flags & VTUN_LZO)
ptr += sprintf(ptr, "L%d", host->zlevel);
case VTUN_ETHER:
*(ptr++) = 'e';
break;
if (host->flags & VTUN_KEEP_ALIVE)
*(ptr++) = 'K';
case VTUN_TUN:
*(ptr++) = 'u';
break;
}
if (host->flags & VTUN_ENCRYPT) {
ptr += sprintf(ptr, "E%d", host->cipher);
}
if( (host->flags & VTUN_SHAPE) /* && host->spd_in */)
ptr += sprintf(ptr,"S%d",host->spd_in);
strcat(ptr, ">");
if( host->flags & VTUN_ZLIB )
ptr += sprintf(ptr,"C%d", host->zlevel);
if( host->flags & VTUN_LZO )
ptr += sprintf(ptr,"L%d", host->zlevel);
if( host->flags & VTUN_KEEP_ALIVE )
*(ptr++) = 'K';
if( host->flags & VTUN_ENCRYPT ) {
ptr += sprintf(ptr,"E%d", host->cipher);
}
strcat(ptr,">");
return str;
}
/* return 1 on success, otherwise 0
Example:
FLAGS: <TuE1>
*/
static int cf2bf(char *str, struct vtun_host *host)
{
char *ptr, *p;
int s;
if( (ptr = strchr(str,'<')) ){
vtun_syslog(LOG_DEBUG,"Remote Server sends %s.", ptr);
ptr++;
while(*ptr){
switch(*ptr++){
case 't':
host->flags |= VTUN_TTY;
break;
case 'p':
host->flags |= VTUN_PIPE;
break;
case 'e':
host->flags |= VTUN_ETHER;
break;
case 'u':
host->flags |= VTUN_TUN;
break;
case 'U':
host->flags &= ~VTUN_PROT_MASK;
host->flags |= VTUN_UDP;
break;
case 'T':
host->flags &= ~VTUN_PROT_MASK;
host->flags |= VTUN_TCP;
break;
case 'K':
host->flags |= VTUN_KEEP_ALIVE;
break;
case 'C':
if((s = strtol(ptr,&p,10)) == ERANGE || ptr == p)
return 0;
host->flags |= VTUN_ZLIB;
host->zlevel = s;
ptr = p;
break;
case 'L':
if((s = strtol(ptr,&p,10)) == ERANGE || ptr == p)
return 0;
host->flags |= VTUN_LZO;
host->zlevel = s;
ptr = p;
break;
case 'E':
/* new form is 'E10', old form is 'E', so remove the
ptr==p check */
if((s = strtol(ptr,&p,10)) == ERANGE) {
vtun_syslog(LOG_ERR,"Garbled encryption method. Bailing out.");
return 0;
}
host->flags |= VTUN_ENCRYPT;
host->cipher = s;
ptr = p;
break;
case 'S':
if((s = strtol(ptr,&p,10)) == ERANGE || ptr == p)
return 0;
if( s ){
host->flags |= VTUN_SHAPE;
host->spd_out = s;
}
ptr = p;
break;
case 'F':
/* reserved for Feature transmit */
break;
case '>':
return 1;
default:
return 0;
}
}
}
return 0;
return str;
}
/*
* Functions to convert binary key data to character string.
* string format: <char_data>
* return 0 on success, otherwise -1
* Example: FLAGS: <TuE1>
*/
static char *cl2cs(char *chal)
static int cf2bf(char *str, struct vtun_host *host)
{
static char str[VTUN_CHAL_SIZE*2+3], *chr="abcdefghijklmnop";
register char *ptr = str;
register int i;
char *ptr, *p;
int s;
*(ptr++) = '<';
for(i=0; i<VTUN_CHAL_SIZE; i++){
*(ptr++) = chr[ ((chal[i] & 0xf0) >> 4) ];
*(ptr++) = chr[ (chal[i] & 0x0f) ];
}
*(ptr++) = '>';
*ptr = '\0';
return str;
}
static int cs2cl(char *str, char *chal)
{
register char *ptr = str;
register int i;
if( !(ptr = strchr(str,'<')) )
return 0;
ptr++;
if( !strtok(ptr,">") || strlen(ptr) != VTUN_CHAL_SIZE*2 )
return 0;
for(i=0; i<VTUN_CHAL_SIZE && *ptr; i++, ptr+=2) {
chal[i] = (*ptr - 'a') << 4;
chal[i] |= *(ptr+1) - 'a';
}
return 1;
if (strlen(str) >= 20) {
return -1;
}
if ((ptr = strchr(str, '<'))) {
vtun_syslog(LOG_DEBUG, "Remote Server sends %s.", ptr);
ptr++;
while (*ptr) {
switch (*ptr++) {
case 't':
host->flags |= VTUN_TTY;
break;
case 'p':
host->flags |= VTUN_PIPE;
break;
case 'e':
host->flags |= VTUN_ETHER;
break;
case 'u':
host->flags |= VTUN_TUN;
break;
case 'U':
host->flags &= ~VTUN_PROT_MASK;
host->flags |= VTUN_UDP;
break;
case 'T':
host->flags &= ~VTUN_PROT_MASK;
host->flags |= VTUN_TCP;
break;
case 'K':
host->flags |= VTUN_KEEP_ALIVE;
break;
case 'C':
if ((s = strtol(ptr, &p, 10)) == ERANGE || ptr == p) {
return -1;
}
host->flags |= VTUN_ZLIB;
host->zlevel = s;
ptr = p;
break;
case 'L':
if ((s = strtol(ptr, &p, 10)) == ERANGE || ptr == p) {
return -1;
}
host->flags |= VTUN_LZO;
host->zlevel = s;
ptr = p;
break;
case 'E':
/* new form is 'E10', old form is 'E', so remove the
ptr==p check */
if ((s = strtol(ptr, &p, 10)) == ERANGE) {
vtun_syslog(LOG_ERR, "Garbled encryption method. Bailing out.");
return -1;
}
host->flags |= VTUN_ENCRYPT;
host->cipher = s;
ptr = p;
break;
case 'S':
if ((s = strtol(ptr, &p, 10)) == ERANGE || ptr == p) {
return -1;
}
if (s > 0) {
host->flags |= VTUN_SHAPE;
host->spd_out = s;
}
ptr = p;
break;
case 'F':
/* reserved for Feature transmit */
break;
case '>':
return 0;
default:
return -1;
}
}
}
return -1;
}
/* Authentication (Server side) */
struct vtun_host * auth_server(int fd)
struct vtun_host *auth_server(int fd)
{
char chal_req[VTUN_CHAL_SIZE], chal_res[VTUN_CHAL_SIZE];
char buf[VTUN_MESG_SIZE], *str1, *str2;
struct vtun_host *h = NULL;
char *host = NULL;
int stage;
char buf[VTUN_MESG_SIZE], *str1, *str2, *str3;
unsigned char cack[crypto_generichash_BYTES];
unsigned char client_pk[crypto_scalarmult_BYTES];
unsigned char server_pk[crypto_scalarmult_BYTES];
unsigned char server_sk[crypto_scalarmult_SCALARBYTES];
unsigned char ckey[4 + crypto_scalarmult_BYTES + crypto_generichash_BYTES];
unsigned char dhkey[crypto_scalarmult_BYTES];
unsigned char skey[crypto_scalarmult_BYTES + crypto_generichash_BYTES];
char skey_hex[2 * (crypto_scalarmult_BYTES + crypto_generichash_BYTES) + 1];
unsigned char hash[crypto_generichash_BYTES];
unsigned char flhash[crypto_generichash_BYTES];
char flhash_hex[2 * crypto_generichash_BYTES + 1];
struct vtun_host *host = NULL;
char *flags;
char *host_name = NULL;
crypto_generichash_state st;
time_t client_now;
size_t bin_len;
int stage;
int success = 0;
set_title("authentication");
set_title("authentication");
print_p(fd,"VTUN server ver %s\n",VTUN_VER);
print_p(fd, "VTUN server ver %s\n", VTUN_VER);
stage = ST_HOST;
stage = ST_STEP2;
while( readn_t(fd, buf, VTUN_MESG_SIZE, vtun.timeout) > 0 ){
buf[sizeof(buf)-1]='\0';
strtok(buf,"\r\n");
while (readn_t(fd, buf, VTUN_MESG_SIZE, vtun.timeout) > 0) {
buf[sizeof(buf) - 1] = '\0';
strtok(buf, "\r\n");
if (!(str1 = strtok(buf, " :"))) {
break;
}
if (!(str2 = strtok(NULL, " :"))) {
break;
}
switch (stage) {
case ST_STEP2:
if (!strcmp(str1, "CKEY")) {
if (!(str3 = strtok(NULL, " \t"))) {
break;
}
sodium_hex2bin(ckey, sizeof ckey, str3, strlen(str3), "", &bin_len, NULL);
if (bin_len != sizeof ckey) {
break;
}
client_now = ((time_t) ckey[0]) << 24 | ((time_t) ckey[1]) << 16 |
((time_t) ckey[2]) << 9 | ((time_t) ckey[3]);
(void) client_now;
host_name = str2;
if ((host = find_host(host_name)) == NULL || derive_key(host) != 0) {
break;
}
crypto_generichash(hash, sizeof hash,
ckey, 4 + crypto_scalarmult_BYTES,
host->akey, crypto_generichash_KEYBYTES);
if (sodium_memcmp(hash, ckey + 4 + crypto_scalarmult_BYTES, sizeof hash) != 0) {
break;
}
memcpy(client_pk, ckey + 4, sizeof client_pk);
randombytes_buf(server_sk, crypto_scalarmult_SCALARBYTES);
crypto_scalarmult_base(server_pk, server_sk);
memcpy(skey, server_pk, sizeof server_pk);
memcpy(skey + crypto_scalarmult_BYTES, hash, sizeof hash);
crypto_generichash(skey + crypto_scalarmult_BYTES, crypto_scalarmult_BYTES,
skey, sizeof skey,
host->akey, crypto_generichash_KEYBYTES);
sodium_bin2hex(skey_hex, sizeof skey_hex, skey, sizeof skey);
print_p(fd, "SKEY: %s\n", skey_hex);
stage = ST_STEP3;
continue;
}
break;
if( !(str1=strtok(buf," :")) )
break;
if( !(str2=strtok(NULL," :")) )
break;
case ST_STEP3:
if (!strcmp(str1, "CACK")) {
sodium_hex2bin(cack, sizeof cack, str2, strlen(str2), "", &bin_len, NULL);
if (bin_len != sizeof cack) {
break;
}
crypto_generichash_init(&st, host->akey, crypto_generichash_KEYBYTES,
crypto_generichash_BYTES);
crypto_generichash_update(&st, (const unsigned char *) "CACK", 4);
crypto_generichash_update(&st, skey, sizeof skey);
crypto_generichash_final(&st, hash, sizeof hash);
if (sodium_memcmp(hash, cack, sizeof hash) != 0) {
break;
}
/* Lock host */
if (lock_host(host) < 0) {
/* Multiple connections are denied */
host = NULL;
break;
}
flags = bf2cf(host);
crypto_generichash_init(&st, host->akey, crypto_generichash_KEYBYTES,
crypto_generichash_BYTES);
crypto_generichash_update(&st, (const unsigned char *) flags, strlen(flags));
crypto_generichash_update(&st, cack, sizeof cack);
crypto_generichash_final(&st, flhash, sizeof flhash);
sodium_bin2hex(flhash_hex, sizeof flhash_hex, flhash, sizeof flhash);
print_p(fd, "FLAGS: %s %s\n", flags, flhash_hex);
switch( stage ){
case ST_HOST:
if( !strcmp(str1,"HOST") ){
host = strdup(str2);
gen_chal(chal_req);
print_p(fd,"OK CHAL: %s\n", cl2cs(chal_req));
stage = ST_CHAL;
continue;
}
break;
case ST_CHAL:
if( !strcmp(str1,"CHAL") ){
if( !cs2cl(str2,chal_res) )
break;
if( !(h = find_host(host)) )
break;
derive_key(h);
auth_chal(chal_req, h);
if( !sodium_memcmp(chal_req, chal_res, VTUN_CHAL_SIZE) ){
/* Auth successeful. */
/* Lock host */
if( lock_host(h) < 0 ){
/* Multiple connections are denied */
h = NULL;
break;
}
print_p(fd,"OK FLAGS: %s\n", bf2cf(h));
} else
h = NULL;
}
break;
}
break;
}
if( host )
free(host);
if( !h )
print_p(fd,"ERR\n");
return h;
crypto_scalarmult(dhkey, server_sk, client_pk);
sodium_memzero(server_sk, sizeof server_sk);
if ((host->key = sodium_malloc(HOST_KEYBYTES)) == NULL) {
abort();
}
crypto_generichash(host->key, HOST_KEYBYTES, dhkey, sizeof dhkey,
host->akey, crypto_generichash_KEYBYTES);
sodium_memzero(dhkey, sizeof dhkey);
success = 1;
}
break;
}
break;
}
if (success == 0) {
print_p(fd, "ERR\n");
host = NULL;
}
return host;
}
/* Authentication (Client side) */
int auth_client(int fd, struct vtun_host *host)
{
char buf[VTUN_MESG_SIZE], chal[VTUN_CHAL_SIZE];
int stage, success=0 ;
char buf[VTUN_MESG_SIZE], *str1, *str2, *str3;
unsigned char cack[crypto_generichash_BYTES];
char cack_hex[2 * crypto_generichash_BYTES + 1];
unsigned char flhash[crypto_generichash_BYTES];
unsigned char hash[crypto_generichash_BYTES];
unsigned char client_pk[crypto_scalarmult_BYTES];
unsigned char client_sk[crypto_scalarmult_SCALARBYTES];
unsigned char server_pk[crypto_scalarmult_BYTES];
unsigned char dhkey[crypto_scalarmult_BYTES];
unsigned char ckey[4 + crypto_scalarmult_BYTES + crypto_generichash_BYTES];
char ckey_hex[2 * (4 + crypto_scalarmult_BYTES + crypto_generichash_BYTES) + 1];
unsigned char skey[crypto_scalarmult_BYTES + crypto_generichash_BYTES];
crypto_generichash_state st;
time_t now;
size_t bin_len;
int stage;
int success = 0;
stage = ST_INIT;
stage = ST_INIT;
while( readn_t(fd, buf, VTUN_MESG_SIZE, vtun.timeout) > 0 ){
buf[sizeof(buf)-1]='\0';
switch( stage ){
case ST_INIT:
if( !strncmp(buf,"VTUN",4) ){
stage = ST_HOST;
print_p(fd,"HOST: %s\n",host->host);
continue;
}
break;
if (derive_key(host) != 0) {
return 0;
}
while (readn_t(fd, buf, VTUN_MESG_SIZE, vtun.timeout) > 0) {
buf[sizeof(buf) - 1] = '\0';
strtok(buf, "\r\n");
if (!(str1 = strtok(buf, " :"))) {
break;
}
if (!(str2 = strtok(NULL, " :"))) {
break;
}
switch (stage) {
case ST_INIT:
if (!strcmp(str1, "VTUN")) {
now = time(NULL);
randombytes_buf(client_sk, crypto_scalarmult_SCALARBYTES);
crypto_scalarmult_base(client_pk, client_sk);
ckey[0] = (unsigned char)(now >> 24);
ckey[1] = (unsigned char)(now >> 16);
ckey[2] = (unsigned char)(now >> 8);
ckey[3] = (unsigned char)(now);
memcpy(ckey + 4, client_pk, crypto_scalarmult_BYTES);
crypto_generichash(ckey + 4 + crypto_scalarmult_BYTES, crypto_generichash_BYTES,
ckey, 4 + crypto_scalarmult_BYTES,
host->akey, crypto_generichash_KEYBYTES);
sodium_bin2hex(ckey_hex, sizeof ckey_hex, ckey, sizeof ckey);
stage = ST_STEP2;
print_p(fd, "CKEY: %s %s\n", host->host, ckey_hex);
continue;
}
break;
case ST_HOST:
if( !strncmp(buf,"OK",2) && cs2cl(buf,chal)){
stage = ST_CHAL;
derive_key(host);
auth_chal(chal, host);
print_p(fd,"CHAL: %s\n", cl2cs(chal));
case ST_STEP2:
if (!strcmp(str1, "SKEY")) {
sodium_hex2bin(skey, sizeof skey, str2, strlen(str2), "", &bin_len, NULL);
if (bin_len != sizeof skey) {
break;
}
crypto_generichash_init(&st, host->akey, crypto_generichash_KEYBYTES,
crypto_generichash_BYTES);
crypto_generichash_update(&st, skey, crypto_scalarmult_BYTES);
crypto_generichash_update(&st, ckey + 4 + crypto_scalarmult_BYTES,
crypto_generichash_BYTES);
crypto_generichash_final(&st, hash, sizeof hash);
if (sodium_memcmp(hash, skey + crypto_scalarmult_BYTES, sizeof hash) != 0) {
break;
}
memcpy(server_pk, skey, sizeof server_pk);
crypto_generichash_init(&st, host->akey, crypto_generichash_KEYBYTES,
crypto_generichash_BYTES);
crypto_generichash_update(&st, (const unsigned char *) "CACK", 4);
crypto_generichash_update(&st, skey, sizeof skey);
crypto_generichash_final(&st, cack, sizeof cack);
sodium_bin2hex(cack_hex, sizeof cack_hex, cack, sizeof cack);
print_p(fd, "CACK: %s\n", cack_hex);
stage = ST_STEP3;
continue;
}
break;
continue;
}
break;
case ST_STEP3:
if (!strcmp(str1, "FLAGS")) {
if (!(str3 = strtok(NULL, " \t"))) {
break;
}
sodium_hex2bin(flhash, sizeof flhash, str3, strlen(str3), "", &bin_len, NULL);
if (bin_len != sizeof flhash) {
break;
}
if (cf2bf(str2, host) != 0) {
break;
}
crypto_generichash_init(&st, host->akey, crypto_generichash_KEYBYTES,
crypto_generichash_BYTES);
crypto_generichash_update(&st, (const unsigned char *) str2, strlen(str2));
crypto_generichash_update(&st, cack, sizeof cack);
crypto_generichash_final(&st, hash, sizeof hash);
if (sodium_memcmp(hash, flhash, sizeof hash) != 0) {
break;
}
crypto_scalarmult(dhkey, client_sk, server_pk);
sodium_memzero(client_sk, sizeof client_sk);
if ((host->key = sodium_malloc(HOST_KEYBYTES)) == NULL) {
abort();
}
crypto_generichash(host->key, HOST_KEYBYTES, dhkey, sizeof dhkey,
host->akey, crypto_generichash_KEYBYTES);
sodium_memzero(dhkey, sizeof dhkey);
success = 1;
}
break;
}
break;
}
case ST_CHAL:
if( !strncmp(buf,"OK",2) && cf2bf(buf,host) )
success = 1;
break;
}
break;
}
return success;
return success;
}

6
auth.h
View File

@ -20,11 +20,9 @@
* $Id: auth.h,v 1.3.2.2 2008/01/07 22:35:19 mtbishop Exp $
*/
#define VTUN_CHAL_SIZE 16
#define ST_INIT 0
#define ST_HOST 1
#define ST_CHAL 2
#define ST_STEP2 1
#define ST_STEP3 2
struct vtun_host * auth_server(int fd);
int auth_client(int fd, struct vtun_host *host);

4
cfg_file.y
View File

@ -29,6 +29,7 @@
#include <stdarg.h>
#include <syslog.h>
#include <sodium.h>
#include "compat.h"
#include "vtun.h"
@ -107,6 +108,7 @@ statement: '\n'
memcpy(parse_host, &default_host, sizeof(struct vtun_host));
parse_host->host = strdup($1);
parse_host->passwd = NULL;
parse_host->akey = NULL;
parse_host->key = NULL;
parse_host->sopt.host = strdup($1);
@ -575,6 +577,8 @@ int free_host(void *d, void *u)
free(h->host);
free(h->passwd);
sodium_free(h->akey);
sodium_free(h->key);
llist_free(&h->up, free_cmd, NULL);
llist_free(&h->down, free_cmd, NULL);

32
lfd_encrypt.c
View File

@ -35,16 +35,6 @@ typedef struct CryptoCtx {
static CryptoCtx ctx;
static int
derive_key(unsigned char *key, size_t key_size, struct vtun_host *host)
{
crypto_generichash(key, key_size, host->key, HOST_KEYBYTES, NULL, 0U);
sodium_free(host->key);
host->key = NULL;
return 0;
}
static int
init_nonce(unsigned char *nonce, size_t nonce_size)
{
@ -69,18 +59,12 @@ init_nonce(unsigned char *nonce, size_t nonce_size)
static int
alloc_encrypt(struct vtun_host *host)
{
unsigned char *key;
if (sodium_init() < 0) {
return -1;
}
key = sodium_malloc(crypto_aead_KEYBYTES);
ctx.state = sodium_malloc(sizeof *ctx.state);
ctx.message = sodium_malloc(MESSAGE_MAX_SIZE);
ctx.ciphertext = sodium_malloc(CIPHERTEXT_MAX_TOTAL_SIZE);
ctx.nonce = sodium_malloc(crypto_aead_NPUBBYTES);
ctx.previous_decrypted_nonce = sodium_malloc(crypto_aead_NPUBBYTES);
if (key == NULL || ctx.state == NULL || ctx.message == NULL ||
if (host->key == NULL || ctx.state == NULL || ctx.message == NULL ||
ctx.ciphertext == NULL || ctx.ciphertext == NULL || ctx.nonce == NULL ||
ctx.previous_decrypted_nonce == NULL) {
abort();
@ -88,11 +72,9 @@ alloc_encrypt(struct vtun_host *host)
if (init_nonce(ctx.nonce, crypto_aead_NPUBBYTES) != 0) {
return -1;
}
if (derive_key(key, crypto_aead_KEYBYTES, host) != 0) {
return -1;
}
crypto_aead_aes256gcm_beforenm(ctx.state, key);
sodium_free(key);
crypto_aead_aes256gcm_beforenm(ctx.state, host->key);
sodium_free(host->key);
host->key = NULL;
return 0;
}
@ -134,7 +116,8 @@ encrypt_buf(int message_len_, char *message_, char ** const ciphertext_p)
crypto_aead_aes256gcm_encrypt_afternm(ctx.ciphertext, &ciphertext_len,
message, message_len,
NULL, 0ULL,
NULL, ctx.nonce, ctx.state);
NULL, ctx.nonce,
(const crypto_aead_aes256gcm_state *) ctx.state);
memcpy(ctx.ciphertext + message_len + crypto_aead_ABYTES,
ctx.nonce, crypto_aead_NPUBBYTES);
sodium_increment(ctx.nonce, crypto_aead_NPUBBYTES);
@ -160,7 +143,8 @@ decrypt_buf(int ciphertext_len_, char *ciphertext_, char ** const message_p)
if (is_lower_or_equal(nonce, ctx.previous_decrypted_nonce, crypto_aead_NPUBBYTES) ||
crypto_aead_aes256gcm_decrypt_afternm(ctx.message, &message_len, NULL,
ciphertext, ciphertext_len,
NULL, 0ULL, nonce, ctx.state) != 0) {
NULL, 0ULL, nonce,
(const crypto_aead_aes256gcm_state *) ctx.state) != 0) {
return -1;
}
memcpy(ctx.previous_decrypted_nonce, nonce, crypto_aead_NPUBBYTES);

4
lib.c
View File

@ -122,7 +122,9 @@ int print_p(int fd,const char *fmt, ...)
/* print the argument string */
va_start(ap, fmt);
vsnprintf(buf,sizeof(buf)-1, fmt, ap);
if (vsnprintf(buf,sizeof(buf)-1, fmt, ap) >= VTUN_MESG_SIZE)
abort();
va_end(ap);
return write_n(fd, buf, sizeof(buf));

3
server.c
View File

@ -43,6 +43,8 @@
#include <arpa/inet.h>
#endif
#include <sodium.h>
#include "vtun.h"
#include "lib.h"
#include "lock.h"
@ -66,6 +68,7 @@ static void connection(int sock)
char *ip;
int opt;
randombytes_stir();
opt = sizeof(struct sockaddr_in);
if( getpeername(sock, (struct sockaddr *) &cl_addr, &opt) ){
vtun_syslog(LOG_ERR, "Can't get peer name");

3
vtun.h
View File

@ -87,6 +87,7 @@ struct vtun_addr {
struct vtun_host {
char *host;
char *passwd;
unsigned char *akey;
unsigned char *key;
char *dev;
@ -171,7 +172,7 @@ extern llist host_list;
#define VTUN_BAD_FRAME 0x8000
/* Authentication message size */
#define VTUN_MESG_SIZE 50
#define VTUN_MESG_SIZE 256
/* Support for multiple connections */
#define VTUN_MULTI_DENY 0 /* no */