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back-port extra checks in pe_crypto from master

This commit is contained in:
arvidn 2016-05-27 09:51:06 -07:00
parent f8dcf30b2e
commit 67a497834a
2 changed files with 47 additions and 13 deletions
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5
include/libtorrent/pe_crypto.hpp
View File

@ -47,10 +47,7 @@ void TORRENT_EXTRA_EXPORT rc4_init(const unsigned char* in, unsigned long len, r
unsigned long TORRENT_EXTRA_EXPORT rc4_encrypt(unsigned char *out, unsigned long outlen, rc4 *state);
#include "libtorrent/aux_/disable_warnings_push.hpp"
#include <boost/asio/buffer.hpp>
#include <list>
#include "libtorrent/aux_/disable_warnings_pop.hpp"
#include "libtorrent/receive_buffer.hpp"
@ -58,6 +55,8 @@ unsigned long TORRENT_EXTRA_EXPORT rc4_encrypt(unsigned char *out, unsigned long
#include "libtorrent/extensions.hpp"
#include "libtorrent/assert.hpp"
#include <list>
namespace libtorrent
{
class TORRENT_EXTRA_EXPORT dh_key_exchange

55
src/pe_crypto.cpp
View File

@ -88,22 +88,35 @@ namespace libtorrent
mp_bigint secret;
mp_bigint key;
// TODO 2: use exceptions for error reporting here
if (mp_read_unsigned_bin(&prime, dh_prime, sizeof(dh_prime)))
{
TORRENT_ASSERT(false);
return;
}
if (mp_read_unsigned_bin(&secret
, reinterpret_cast<unsigned char*>(m_dh_local_secret)
, sizeof(m_dh_local_secret)))
{
TORRENT_ASSERT(false);
return;
}
// generator is 2
mp_set_int(&key, 2);
// key = (2 ^ secret) % prime
if (mp_exptmod(&key, &secret, &prime, &key))
{
TORRENT_ASSERT(false);
return;
}
// key is now our local key
int size = mp_unsigned_bin_size(&key);
memset(m_dh_local_key, 0, sizeof(m_dh_local_key) - size);
int const size = mp_unsigned_bin_size(&key);
TORRENT_ASSERT(size >= 0);
TORRENT_ASSERT(size <= sizeof(m_dh_local_key));
if (size < 0 || size > sizeof(m_dh_local_key)) return;
std::memset(m_dh_local_key, 0, sizeof(m_dh_local_key) - size);
mp_to_unsigned_bin(&key
, reinterpret_cast<unsigned char*>(m_dh_local_key)
+ sizeof(m_dh_local_key) - size);
@ -122,22 +135,42 @@ namespace libtorrent
mp_bigint secret;
mp_bigint remote_key;
// TODO 2: use exceptions for error reporting here
if (mp_read_unsigned_bin(&prime, dh_prime, sizeof(dh_prime)))
{
TORRENT_ASSERT(false);
return -1;
}
if (mp_read_unsigned_bin(&secret
, reinterpret_cast<unsigned char*>(m_dh_local_secret)
, sizeof(m_dh_local_secret)))
{
TORRENT_ASSERT(false);
return -1;
}
if (mp_read_unsigned_bin(&remote_key
, reinterpret_cast<const unsigned char*>(remote_pubkey), 96))
{
TORRENT_ASSERT(false);
return -1;
}
if (mp_exptmod(&remote_key, &secret, &prime, &remote_key))
{
TORRENT_ASSERT(false);
return -1;
}
// remote_key is now the shared secret
int size = mp_unsigned_bin_size(&remote_key);
memset(m_dh_shared_secret, 0, sizeof(m_dh_shared_secret) - size);
int const size = mp_unsigned_bin_size(&remote_key);
TORRENT_ASSERT(size >= 0);
TORRENT_ASSERT(size <= sizeof(m_dh_shared_secret));
if (size < 0 || size > sizeof(m_dh_shared_secret))
{
return -1;
}
std::memset(m_dh_shared_secret, 0, sizeof(m_dh_shared_secret) - size);
mp_to_unsigned_bin(&remote_key
, reinterpret_cast<unsigned char*>(m_dh_shared_secret)
+ sizeof(m_dh_shared_secret) - size);
@ -368,11 +401,13 @@ namespace libtorrent
void rc4_init(const unsigned char* in, unsigned long len, rc4 *state)
{
unsigned char key[256], tmp, *s;
size_t const key_size = sizeof(state->buf);
unsigned char key[key_size], tmp, *s;
int keylen, x, y, j;
TORRENT_ASSERT(state != 0);
TORRENT_ASSERT(len <= 256);
TORRENT_ASSERT(len <= key_size);
if (len > key_size) len = key_size;
state->x = 0;
while (len--) {
@ -381,18 +416,18 @@ void rc4_init(const unsigned char* in, unsigned long len, rc4 *state)
/* extract the key */
s = state->buf;
memcpy(key, s, 256);
std::memcpy(key, s, key_size);
keylen = state->x;
/* make RC4 perm and shuffle */
for (x = 0; x < 256; x++) {
for (x = 0; x < key_size; ++x) {
s[x] = x;
}
for (j = x = y = 0; x < 256; x++) {
for (j = x = y = 0; x < key_size; x++) {
y = (y + state->buf[x] + key[j++]) & 255;
if (j == keylen) {
j = 0;
j = 0;
}
tmp = s[x]; s[x] = s[y]; s[y] = tmp;
}