/*
* Copyright (c) 2018-2025 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 <netinet/in.h>
#include "dnscap_common.h"
#if defined(HAVE_LIBCRYPTO) && defined(HAVE_OPENSSL_CONF_H) && defined(HAVE_OPENSSL_ERR_H) && defined(HAVE_OPENSSL_EVP_H)
#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#define USE_OPENSSL 1
#include "edns0_ecs.c"
#endif
static set_iaddr_t anonaes128_set_iaddr = 0;
static logerr_t* logerr;
static int only_clients = 0, only_servers = 0, dns_port = 53, encrypt_v4 = 0, decrypt = 0, edns = 0;
static unsigned char key[16];
static unsigned char iv[16];
#ifdef USE_OPENSSL
static EVP_CIPHER_CTX* ctx = 0;
#endif
enum plugin_type anonaes128_type()
{
return plugin_filter;
}
void usage(const char* msg)
{
fprintf(stderr, "anonaes128.so usage error: %s\n", msg);
exit(1);
}
void anonaes128_usage()
{
fprintf(stderr,
"\nanonaes128.so options:\n"
"\t-? print these instructions and exit\n"
"\t-k <key> A 16 character long key\n"
"\t-K <file> Read the 16 first bytes from file and use as key\n"
"\t-i <key> A 16 character long Initialisation Vector (IV)\n"
"\t-I <file> Read the 16 first bytes from file and use as IV\n"
"\t-D Decrypt IPv6 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-4 Encrypt IPv4 addresses, not default or recommended\n"
"\t-e Also en/de-crypt EDNS(0) Client Subnet\n"
"\t-E ONLY en/de-crypt EDNS(0) Client Subnet, not IP addresses\n");
}
void anonaes128_extension(int ext, void* arg)
{
switch (ext) {
case DNSCAP_EXT_SET_IADDR:
anonaes128_set_iaddr = (set_iaddr_t)arg;
break;
}
}
void anonaes128_getopt(int* argc, char** argv[])
{
int c, got_key = 0, got_iv = 0;
unsigned long ul;
char* p;
while ((c = getopt(*argc, *argv, "?k:K:i:I:Dcsp:4eE")) != 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 'K': {
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 'i':
if (strlen(optarg) != 16) {
usage("IV must be 16 characters long");
}
memcpy(iv, optarg, 16);
got_iv = 1;
break;
case 'I': {
int fd;
ssize_t r;
if ((fd = open(optarg, O_RDONLY)) < 0) {
perror("open()");
usage("unable to open IV file");
}
if ((r = read(fd, iv, 16)) < 0) {
perror("read()");
usage("unable to read from IV file");
}
if (r != 16) {
usage("unable to read 16 bytes from IV file");
}
close(fd);
got_iv = 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 '4':
encrypt_v4 = 1;
break;
case 'e':
if (!edns)
edns = 1;
break;
case 'E':
edns = -1;
break;
case '?':
anonaes128_usage();
if (!optopt || optopt == '?') {
exit(0);
}
// fallthrough
default:
exit(1);
}
}
if (!got_key || !got_iv) {
usage("must have key (-k/-K) and IV (-i/-I)");
}
if (decrypt && encrypt_v4) {
usage("decryption (-D) can not be done for IPv4 addresses (-4)");
}
#ifdef USE_OPENSSL
if (!(ctx = EVP_CIPHER_CTX_new())) {
usage("unable to create openssl cipher context");
}
if (!EVP_CipherInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, iv, decrypt ? 0 : 1)) {
unsigned long e = ERR_get_error();
fprintf(stderr, "%s:%s:%s\n",
ERR_lib_error_string(e),
#if OPENSSL_VERSION_NUMBER < 0x30000000L
ERR_func_error_string(e),
#else
"",
#endif
ERR_reason_error_string(e));
usage("unable to initialize AES128 cipher");
}
EVP_CIPHER_CTX_set_padding(ctx, 0);
#else
usage("no openssl support built in, can't encrypt IP addresses");
#endif
if (only_clients && only_servers) {
usage("-c and -s options are mutually exclusive");
}
}
int anonaes128_start(logerr_t* a_logerr)
{
logerr = a_logerr;
return 0;
}
void anonaes128_stop()
{
#ifdef USE_OPENSSL
EVP_CIPHER_CTX_free(ctx);
ctx = 0;
#endif
}
int anonaes128_open(my_bpftimeval ts)
{
return 0;
}
int anonaes128_close(my_bpftimeval ts)
{
return 0;
}
#ifdef USE_OPENSSL
void ecs_callback(int family, u_char* buf, size_t len)
{
unsigned char outbuf[16 + EVP_MAX_BLOCK_LENGTH] = { 0 };
int outlen = 0;
struct in6_addr in6 = IN6ADDR_ANY_INIT;
switch (family) {
case 1: // IPv4
if (len > sizeof(struct in_addr))
break;
if (encrypt_v4) {
memcpy(&in6, buf, len);
memcpy(((uint8_t*)&in6) + 4, &in6, 4);
memcpy(((uint8_t*)&in6) + 8, &in6, 4);
memcpy(((uint8_t*)&in6) + 12, &in6, 4);
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (void*)&in6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(buf, outbuf, len);
}
break;
case 2: // IPv6
if (len > sizeof(struct in6_addr))
break;
memcpy(&in6, buf, len);
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (void*)&in6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(buf, outbuf, len);
break;
default:
break;
}
}
#endif
int anonaes128_filter(const char* descr, iaddr* from, iaddr* to, uint8_t proto, unsigned flags,
unsigned sport, unsigned dport, my_bpftimeval ts,
u_char* pkt_copy, const unsigned olen,
u_char* payload, const unsigned payloadlen)
{
#ifdef USE_OPENSSL
if (edns && flags & DNSCAP_OUTPUT_ISDNS && payload && payloadlen > DNS_MSG_HDR_SZ) {
parse_for_edns0_ecs(payload, payloadlen, ecs_callback);
if (edns < 0)
return 0;
}
unsigned char outbuf[16 + EVP_MAX_BLOCK_LENGTH];
int outlen = 0;
for (;;) {
if (only_clients && sport == dns_port) {
if (sport != dport) {
from = 0;
break;
}
}
if (only_servers && sport != dns_port) {
from = 0;
break;
}
switch (from->af) {
case AF_INET6:
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&from->u.a6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(&from->u.a6, outbuf, 16);
break;
case AF_INET:
if (encrypt_v4) {
memcpy(((uint8_t*)&from->u.a6) + 4, &from->u.a4, 4);
memcpy(((uint8_t*)&from->u.a6) + 8, &from->u.a4, 4);
memcpy(((uint8_t*)&from->u.a6) + 12, &from->u.a4, 4);
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&from->u.a6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(&from->u.a4, outbuf, 4);
break;
}
default:
from = 0;
break;
}
break;
}
for (;;) {
if (only_clients && dport == dns_port) {
if (dport != sport) {
to = 0;
break;
}
}
if (only_servers && dport != dns_port) {
to = 0;
break;
}
switch (to->af) {
case AF_INET6:
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&to->u.a6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(&to->u.a6, outbuf, 16);
break;
case AF_INET:
if (encrypt_v4) {
memcpy(((uint8_t*)&to->u.a6) + 4, &to->u.a4, 4);
memcpy(((uint8_t*)&to->u.a6) + 8, &to->u.a4, 4);
memcpy(((uint8_t*)&to->u.a6) + 12, &to->u.a4, 4);
if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&to->u.a6, 16)) {
logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
exit(1);
}
if (outlen != 16) {
logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
exit(1);
}
memcpy(&to->u.a4, outbuf, 4);
break;
}
default:
to = 0;
break;
}
break;
}
if (anonaes128_set_iaddr && (from || to)) {
anonaes128_set_iaddr(from, to);
}
#endif
return 0;
}