348 lines
11 KiB
C
348 lines
11 KiB
C
/*
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* Copyright (c) 2018-2023, OARC, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "dnscap_common.h"
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#if defined(HAVE_LIBCRYPTO) && defined(HAVE_OPENSSL_CONF_H) && defined(HAVE_OPENSSL_ERR_H) && defined(HAVE_OPENSSL_EVP_H)
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#include <openssl/conf.h>
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#include <openssl/evp.h>
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#include <openssl/err.h>
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#define USE_OPENSSL 1
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#endif
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static set_iaddr_t anonaes128_set_iaddr = 0;
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static logerr_t* logerr;
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static int only_clients = 0, only_servers = 0, dns_port = 53, encrypt_v4 = 0, decrypt = 0;
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static unsigned char key[16];
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static unsigned char iv[16];
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#ifdef USE_OPENSSL
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static EVP_CIPHER_CTX* ctx = 0;
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#endif
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enum plugin_type anonaes128_type()
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{
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return plugin_filter;
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}
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void usage(const char* msg)
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{
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fprintf(stderr, "anonaes128.so usage error: %s\n", msg);
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exit(1);
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}
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void anonaes128_usage()
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{
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fprintf(stderr,
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"\nanonaes128.so options:\n"
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"\t-? print these instructions and exit\n"
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"\t-k <key> A 16 character long key\n"
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"\t-K <file> Read the 16 first bytes from file and use as key\n"
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"\t-i <key> A 16 character long Initialisation Vector (IV)\n"
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"\t-I <file> Read the 16 first bytes from file and use as IV\n"
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"\t-D Decrypt IPv6 addresses\n"
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"\t-c Only en/de-crypt clients (port != 53)\n"
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"\t-s Only en/de-crypt servers (port == 53)\n"
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"\t-p <port> Set port for -c/-s, default 53\n"
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"\t-4 Encrypt IPv4 addresses, not default or recommended\n");
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}
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void anonaes128_extension(int ext, void* arg)
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{
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switch (ext) {
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case DNSCAP_EXT_SET_IADDR:
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anonaes128_set_iaddr = (set_iaddr_t)arg;
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break;
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}
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}
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void anonaes128_getopt(int* argc, char** argv[])
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{
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int c, got_key = 0, got_iv = 0;
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unsigned long ul;
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char* p;
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while ((c = getopt(*argc, *argv, "?k:K:i:I:Dcsp:4")) != EOF) {
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switch (c) {
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case 'k':
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if (strlen(optarg) != 16) {
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usage("key must be 16 characters long");
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}
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memcpy(key, optarg, 16);
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got_key = 1;
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break;
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case 'K': {
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int fd;
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ssize_t r;
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if ((fd = open(optarg, O_RDONLY)) < 0) {
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perror("open()");
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usage("unable to open key file");
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}
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if ((r = read(fd, key, 16)) < 0) {
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perror("read()");
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usage("unable to read from key file");
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}
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if (r != 16) {
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usage("unable to read 16 bytes from key file");
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}
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close(fd);
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got_key = 1;
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break;
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}
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case 'i':
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if (strlen(optarg) != 16) {
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usage("IV must be 16 characters long");
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}
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memcpy(iv, optarg, 16);
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got_iv = 1;
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break;
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case 'I': {
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int fd;
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ssize_t r;
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if ((fd = open(optarg, O_RDONLY)) < 0) {
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perror("open()");
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usage("unable to open IV file");
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}
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if ((r = read(fd, iv, 16)) < 0) {
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perror("read()");
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usage("unable to read from IV file");
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}
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if (r != 16) {
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usage("unable to read 16 bytes from IV file");
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}
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close(fd);
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got_iv = 1;
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break;
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}
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case 'D':
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decrypt = 1;
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break;
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case 'c':
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only_clients = 1;
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break;
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case 's':
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only_servers = 1;
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break;
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case 'p':
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ul = strtoul(optarg, &p, 0);
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if (*p != '\0' || ul < 1U || ul > 65535U)
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usage("port must be an integer 1..65535");
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dns_port = (unsigned)ul;
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break;
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case '4':
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encrypt_v4 = 1;
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break;
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case '?':
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anonaes128_usage();
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if (!optopt || optopt == '?') {
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exit(0);
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}
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// fallthrough
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default:
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exit(1);
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}
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}
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if (!got_key || !got_iv) {
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usage("must have key (-k/-K) and IV (-i/-I)");
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}
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if (decrypt && encrypt_v4) {
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usage("decryption (-D) can not be done for IPv4 addresses (-4)");
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}
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#ifdef USE_OPENSSL
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if (!(ctx = EVP_CIPHER_CTX_new())) {
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usage("unable to create openssl cipher context");
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}
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if (!EVP_CipherInit_ex(ctx, EVP_aes_128_ecb(), NULL, key, iv, decrypt ? 0 : 1)) {
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unsigned long e = ERR_get_error();
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fprintf(stderr, "%s:%s:%s", ERR_lib_error_string(e), ERR_func_error_string(e), ERR_reason_error_string(e));
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usage("unable to initialize AES128 cipher");
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}
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EVP_CIPHER_CTX_set_padding(ctx, 0);
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#else
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usage("no openssl support built in, can't encrypt IP addresses");
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#endif
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if (only_clients && only_servers) {
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usage("-c and -s options are mutually exclusive");
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}
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}
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int anonaes128_start(logerr_t* a_logerr)
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{
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logerr = a_logerr;
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return 0;
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}
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void anonaes128_stop()
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{
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#ifdef USE_OPENSSL
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EVP_CIPHER_CTX_free(ctx);
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ctx = 0;
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#endif
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}
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int anonaes128_open(my_bpftimeval ts)
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{
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return 0;
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}
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int anonaes128_close(my_bpftimeval ts)
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{
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return 0;
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}
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int anonaes128_filter(const char* descr, iaddr* from, iaddr* to, uint8_t proto, unsigned flags,
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unsigned sport, unsigned dport, my_bpftimeval ts,
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const u_char* pkt_copy, const unsigned olen,
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const u_char* payload, const unsigned payloadlen)
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{
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#ifdef USE_OPENSSL
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unsigned char outbuf[16 + EVP_MAX_BLOCK_LENGTH];
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int outlen = 0;
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for (;;) {
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if (only_clients && sport == dns_port) {
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if (sport != dport) {
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from = 0;
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break;
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}
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}
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if (only_servers && sport != dns_port) {
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from = 0;
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break;
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}
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switch (from->af) {
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case AF_INET6:
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if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&from->u.a6, 16)) {
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logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
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exit(1);
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}
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if (outlen != 16) {
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logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
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exit(1);
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}
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memcpy(&from->u.a6, outbuf, 16);
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break;
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case AF_INET:
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if (encrypt_v4) {
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memcpy(((uint8_t*)&from->u.a6) + 4, &from->u.a4, 4);
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memcpy(((uint8_t*)&from->u.a6) + 8, &from->u.a4, 4);
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memcpy(((uint8_t*)&from->u.a6) + 12, &from->u.a4, 4);
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if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&from->u.a6, 16)) {
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logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
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exit(1);
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}
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if (outlen != 16) {
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logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
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exit(1);
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}
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memcpy(&from->u.a4, outbuf, 4);
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break;
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}
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default:
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from = 0;
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break;
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}
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break;
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}
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for (;;) {
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if (only_clients && dport == dns_port) {
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if (dport != sport) {
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to = 0;
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break;
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}
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}
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if (only_servers && dport != dns_port) {
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to = 0;
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break;
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}
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switch (to->af) {
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case AF_INET6:
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if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&to->u.a6, 16)) {
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logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
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exit(1);
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}
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if (outlen != 16) {
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logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
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exit(1);
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}
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memcpy(&to->u.a6, outbuf, 16);
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break;
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case AF_INET:
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if (encrypt_v4) {
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memcpy(((uint8_t*)&to->u.a6) + 4, &to->u.a4, 4);
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memcpy(((uint8_t*)&to->u.a6) + 8, &to->u.a4, 4);
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memcpy(((uint8_t*)&to->u.a6) + 12, &to->u.a4, 4);
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if (!EVP_CipherUpdate(ctx, outbuf, &outlen, (unsigned char*)&to->u.a6, 16)) {
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logerr("anonaes128.so: error en/de-crypting IP address: %s", ERR_reason_error_string(ERR_get_error()));
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exit(1);
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}
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if (outlen != 16) {
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logerr("anonaes128.so: error en/de-crypted output is not 16 bytes");
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exit(1);
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}
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memcpy(&to->u.a4, outbuf, 4);
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break;
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}
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default:
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to = 0;
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break;
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}
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break;
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}
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if (anonaes128_set_iaddr && (from || to)) {
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anonaes128_set_iaddr(from, to);
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}
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#endif
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return 0;
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}
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