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dnscap/plugins/ipcrypt/ipcrypt.c
Daniel Baumann 813dbc4406
Merging upstream version 2.0.2. 
Signed-off-by: Daniel Baumann <daniel@debian.org>
2025-02-08 12:03:14 +01:00

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/*
* Copyright (c) 2018-2022, OARC, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "dnscap_common.h"
static set_iaddr_t ipcrypt_set_iaddr = 0;
static logerr_t* logerr;
static int only_clients = 0, only_servers = 0, dns_port = 53, iterations = 1, encrypt_v6 = 0, decrypt = 0;
static uint8_t key[16];
/*
* ipcrypt based on Python and Go code at https://github.com/veorq/ipcrypt
* by Jean-Philippe Aumasson jeanphilippe.aumasson@gmail.com
*/
static inline uint8_t rotl(uint8_t b, int r)
{
return (b << r) | (b >> (8 - r));
}
static inline void permute_fwd(uint8_t* state)
{
state[0] += state[1];
state[2] += state[3];
state[1] = rotl(state[1], 2) ^ state[0];
state[3] = rotl(state[3], 5) ^ state[2];
// state[1] ^= state[0];
// state[3] ^= state[2];
state[0] = rotl(state[0], 4) + state[3];
// state[0] += state[3];
state[2] += state[1];
state[1] = rotl(state[1], 3) ^ state[2];
state[3] = rotl(state[3], 7) ^ state[0];
// state[1] ^= state[2];
// state[3] ^= state[0];
state[2] = rotl(state[2], 4);
}
static inline void permute_bwd(uint8_t* state)
{
state[2] = rotl(state[2], 4);
state[1] ^= state[2];
state[3] ^= state[0];
state[1] = rotl(state[1], 5);
state[3] = rotl(state[3], 1);
state[0] -= state[3];
state[2] -= state[1];
state[0] = rotl(state[0], 4);
state[1] ^= state[0];
state[3] ^= state[2];
state[1] = rotl(state[1], 6);
state[3] = rotl(state[3], 3);
state[0] -= state[1];
state[2] -= state[3];
}
static inline void xor4(uint8_t* x, uint8_t* y)
{
*(uint32_t*)x ^= *(uint32_t*)y;
// x[0] ^= y[0];
// x[1] ^= y[1];
// x[2] ^= y[2];
// x[3] ^= y[3];
}
static inline void _encrypt(uint8_t* ip)
{
int i = iterations;
for (; i; i--) {
xor4(ip, key);
permute_fwd(ip);
xor4(ip, &key[4]);
permute_fwd(ip);
xor4(ip, &key[8]);
permute_fwd(ip);
xor4(ip, &key[12]);
}
}
static inline void _decrypt(uint8_t* ip)
{
int i = iterations;
for (; i; i--) {
xor4(ip, &key[12]);
permute_bwd(ip);
xor4(ip, &key[8]);
permute_bwd(ip);
xor4(ip, &key[4]);
permute_bwd(ip);
xor4(ip, key);
}
}
enum plugin_type ipcrypt_type()
{
return plugin_filter;
}
void usage(const char* msg)
{
fprintf(stderr, "ipcrypt.so usage error: %s\n", msg);
exit(1);
}
void ipcrypt_usage()
{
fprintf(stderr,
"\nipcrypt.so options:\n"
"\t-? print these instructions and exit\n"
"\t-k <key> A 16 character long key\n"
"\t-f <file> Read the 16 first bytes from file and use as key\n"
"\t-D Decrypt IP addresses\n"
"\t-c Only en/de-crypt clients (port != 53)\n"
"\t-s Only en/de-crypt servers (port == 53)\n"
"\t-p <port> Set port for -c/-s, default 53\n"
"\t-i <num> Number of en/de-cryption iterations, default 1\n"
"\t-6 En/de-crypt IPv6 addresses, not default or recommended\n");
}
void ipcrypt_extension(int ext, void* arg)
{
switch (ext) {
case DNSCAP_EXT_SET_IADDR:
ipcrypt_set_iaddr = (set_iaddr_t)arg;
break;
}
}
void ipcrypt_getopt(int* argc, char** argv[])
{
int c, got_key = 0;
unsigned long ul;
char* p;
while ((c = getopt(*argc, *argv, "?k:f:Dcsp:i:6")) != EOF) {
switch (c) {
case 'k':
if (strlen(optarg) != 16) {
usage("key must be 16 characters long");
}
memcpy(key, optarg, 16);
got_key = 1;
break;
case 'f': {
int fd;
ssize_t r;
if ((fd = open(optarg, O_RDONLY)) < 0) {
perror("open()");
usage("unable to open key file");
}
if ((r = read(fd, key, 16)) < 0) {
perror("read()");
usage("unable to read from key file");
}
if (r != 16) {
usage("unable to read 16 bytes from key file");
}
close(fd);
got_key = 1;
break;
}
case 'D':
decrypt = 1;
break;
case 'c':
only_clients = 1;
break;
case 's':
only_servers = 1;
break;
case 'p':
ul = strtoul(optarg, &p, 0);
if (*p != '\0' || ul < 1U || ul > 65535U)
usage("port must be an integer 1..65535");
dns_port = (unsigned)ul;
break;
case 'i':
ul = strtoul(optarg, &p, 0);
if (*p != '\0' || ul < 1U || ul > 65535U)
usage("iterations must be an integer 1..65535");
iterations = (unsigned)ul;
break;
case '6':
encrypt_v6 = 1;
break;
case '?':
ipcrypt_usage();
if (!optopt || optopt == '?') {
exit(0);
}
// fallthrough
default:
exit(1);
}
}
if (!got_key) {
usage("must have -k <key> or -f <file>");
}
if (only_clients && only_servers) {
usage("-c and -s options are mutually exclusive");
}
}
int ipcrypt_start(logerr_t* a_logerr)
{
logerr = a_logerr;
return 0;
}
void ipcrypt_stop()
{
}
int ipcrypt_open(my_bpftimeval ts)
{
return 0;
}
int ipcrypt_close(my_bpftimeval ts)
{
return 0;
}
int ipcrypt_filter(const char* descr, iaddr* from, iaddr* to, uint8_t proto, unsigned flags,
unsigned sport, unsigned dport, my_bpftimeval ts,
const u_char* pkt_copy, const unsigned olen,
const u_char* payload, const unsigned payloadlen)
{
for (;;) {
if (only_clients && sport == dns_port) {
from = 0;
break;
}
if (only_servers && sport != dns_port) {
from = 0;
break;
}
switch (from->af) {
case AF_INET:
decrypt ? _decrypt((uint8_t*)&from->u.a4) : _encrypt((uint8_t*)&from->u.a4);
break;
case AF_INET6:
if (encrypt_v6) {
if (decrypt) {
_decrypt((uint8_t*)&from->u.a6);
_decrypt(((uint8_t*)&from->u.a6) + 4);
_decrypt(((uint8_t*)&from->u.a6) + 8);
_decrypt(((uint8_t*)&from->u.a6) + 12);
} else {
_encrypt((uint8_t*)&from->u.a6);
_encrypt(((uint8_t*)&from->u.a6) + 4);
_encrypt(((uint8_t*)&from->u.a6) + 8);
_encrypt(((uint8_t*)&from->u.a6) + 12);
}
break;
}
default:
from = 0;
break;
}
break;
}
for (;;) {
if (only_clients && dport == dns_port) {
to = 0;
break;
}
if (only_servers && dport != dns_port) {
to = 0;
break;
}
switch (to->af) {
case AF_INET:
decrypt ? _decrypt((uint8_t*)&to->u.a4) : _encrypt((uint8_t*)&to->u.a4);
break;
case AF_INET6:
if (encrypt_v6) {
if (decrypt) {
_decrypt((uint8_t*)&to->u.a6);
_decrypt(((uint8_t*)&to->u.a6) + 4);
_decrypt(((uint8_t*)&to->u.a6) + 8);
_decrypt(((uint8_t*)&to->u.a6) + 12);
} else {
_encrypt((uint8_t*)&to->u.a6);
_encrypt(((uint8_t*)&to->u.a6) + 4);
_encrypt(((uint8_t*)&to->u.a6) + 8);
_encrypt(((uint8_t*)&to->u.a6) + 12);
}
break;
}
default:
to = 0;
break;
}
break;
}
if (ipcrypt_set_iaddr && (from || to)) {
ipcrypt_set_iaddr(from, to);
}
return 0;
}
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