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-rw-r--r--plugins/cryptopan/cryptopan.c475
1 files changed, 475 insertions, 0 deletions
diff --git a/plugins/cryptopan/cryptopan.c b/plugins/cryptopan/cryptopan.c
new file mode 100644
index 0000000..2e439af
--- /dev/null
+++ b/plugins/cryptopan/cryptopan.c
@@ -0,0 +1,475 @@
+/*
+ * Copyright (c) 2018-2021, 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.
+ */
+
+/*
+ * Crypto-PAn encryption based on submitted extension by David Stott (Lucent)
+ * https://www.cc.gatech.edu/computing/Networking/projects/cryptopan/lucent.shtml
+ */
+
+#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"
+
+#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
+#endif
+
+static set_iaddr_t cryptopan_set_iaddr = 0;
+
+static logerr_t* logerr;
+static int only_clients = 0, only_servers = 0, dns_port = 53, encrypt_v6 = 0, decrypt = 0;
+static unsigned char key[16];
+static unsigned char iv[16];
+static unsigned char pad[16];
+#ifdef USE_OPENSSL
+static EVP_CIPHER_CTX* ctx = 0;
+#endif
+
+enum plugin_type cryptopan_type()
+{
+ return plugin_filter;
+}
+
+void usage(const char* msg)
+{
+ fprintf(stderr, "cryptopan.so usage error: %s\n", msg);
+ exit(1);
+}
+
+void cryptopan_usage()
+{
+ fprintf(stderr,
+ "\ncryptopan.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-a <key> A 16 character long padding\n"
+ "\t-A <file> Read the 16 first bytes from file and use as padding\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-6 En/de-crypt IPv6 addresses, not default or recommended\n");
+}
+
+void cryptopan_extension(int ext, void* arg)
+{
+ switch (ext) {
+ case DNSCAP_EXT_SET_IADDR:
+ cryptopan_set_iaddr = (set_iaddr_t)arg;
+ break;
+ }
+}
+
+void cryptopan_getopt(int* argc, char** argv[])
+{
+ int c, got_key = 0, got_iv = 0, got_pad = 0;
+ unsigned long ul;
+ char* p;
+
+ while ((c = getopt(*argc, *argv, "?k:K:i:I:a:A:Dcsp: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 '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 'a':
+ if (strlen(optarg) != 16) {
+ usage("padding must be 16 characters long");
+ }
+ memcpy(pad, optarg, 16);
+ got_pad = 1;
+ break;
+ case 'A': {
+ int fd;
+ ssize_t r;
+ if ((fd = open(optarg, O_RDONLY)) < 0) {
+ perror("open()");
+ usage("unable to open padding file");
+ }
+ if ((r = read(fd, pad, 16)) < 0) {
+ perror("read()");
+ usage("unable to read from padding file");
+ }
+ if (r != 16) {
+ usage("unable to read 16 bytes from padding file");
+ }
+ close(fd);
+ got_pad = 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 '6':
+ encrypt_v6 = 1;
+ break;
+ case '?':
+ cryptopan_usage();
+ if (!optopt || optopt == '?') {
+ exit(0);
+ }
+ // fallthrough
+ default:
+ exit(1);
+ }
+ }
+
+ if (!got_key || !got_iv || !got_pad) {
+ usage("must have key (-k/-K), IV (-i/-I) and padding (-a/-A)");
+ }
+
+#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, 1)) {
+ unsigned long e = ERR_get_error();
+ fprintf(stderr, "%s:%s:%s\n", ERR_lib_error_string(e), ERR_func_error_string(e), ERR_reason_error_string(e));
+ usage("unable to initialize AES128 cipher");
+ }
+ EVP_CIPHER_CTX_set_padding(ctx, 0);
+ {
+ unsigned char outbuf[16 + EVP_MAX_BLOCK_LENGTH];
+ int outlen = 0;
+
+ if (!EVP_CipherUpdate(ctx, outbuf, &outlen, pad, 16)) {
+ fprintf(stderr, "cryptopan.so: error encrypting padding: %s\n", ERR_reason_error_string(ERR_get_error()));
+ exit(1);
+ }
+ if (outlen != 16) {
+ fprintf(stderr, "cryptopan.so: error encrypted padding is not 16 bytes\n");
+ exit(1);
+ }
+ memcpy(&pad, outbuf, 16);
+ }
+#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 cryptopan_start(logerr_t* a_logerr)
+{
+ logerr = a_logerr;
+ return 0;
+}
+
+void cryptopan_stop()
+{
+#ifdef USE_OPENSSL
+ EVP_CIPHER_CTX_free(ctx);
+ ctx = 0;
+#endif
+}
+
+int cryptopan_open(my_bpftimeval ts)
+{
+ return 0;
+}
+
+int cryptopan_close(my_bpftimeval ts)
+{
+ return 0;
+}
+
+#ifdef USE_OPENSSL
+struct input {
+ union {
+ unsigned char input[16];
+ uint32_t ui32;
+ } u;
+};
+struct output {
+ union {
+ unsigned char outbuf[16 + EVP_MAX_BLOCK_LENGTH];
+ uint32_t ui32;
+ } u;
+};
+static inline void _encrypt(uint32_t* in)
+{
+ struct input input;
+ struct output output;
+ int outlen = 0, pos;
+ uint32_t orig, result = 0, pad4b, mask = 0;
+
+ memcpy(input.u.input, pad, 16);
+ orig = ntohl(*in);
+ memcpy(&pad4b, pad, 4);
+
+ // First pass with padding only
+
+ input.u.ui32 = htonl(pad4b);
+
+ if (!EVP_CipherUpdate(ctx, output.u.outbuf, &outlen, input.u.input, 16)) {
+ fprintf(stderr, "cryptopan.so: error encrypting: %s\n", ERR_reason_error_string(ERR_get_error()));
+ exit(1);
+ }
+ if (outlen != 16) {
+ fprintf(stderr, "cryptopan.so: error encrypted result is not 16 bytes\n");
+ exit(1);
+ }
+
+ result |= ntohl(output.u.ui32) & 0x80000000;
+ mask >>= 1;
+ mask |= 0x80000000;
+
+ for (pos = 1; pos < 32; pos++) {
+ input.u.ui32 = htonl(((pad4b << pos) | (pad4b >> (32 - pos))) ^ (orig & mask));
+
+ if (!EVP_CipherUpdate(ctx, output.u.outbuf, &outlen, input.u.input, 16)) {
+ fprintf(stderr, "cryptopan.so: error encrypting: %s\n", ERR_reason_error_string(ERR_get_error()));
+ exit(1);
+ }
+ if (outlen != 16) {
+ fprintf(stderr, "cryptopan.so: error encrypted result is not 16 bytes\n");
+ exit(1);
+ }
+
+ result |= (ntohl(output.u.ui32) & 0x80000000) >> pos;
+ mask >>= 1;
+ mask |= 0x80000000;
+ }
+
+ *in = htonl(result ^ orig);
+}
+
+static inline void _decrypt(uint32_t* in)
+{
+ struct input input;
+ struct output output;
+ int outlen = 0, pos;
+ uint32_t orig, pad4b, mask = 0;
+
+ memcpy(input.u.input, pad, 16);
+ orig = ntohl(*in);
+ memcpy(&pad4b, pad, 4);
+
+ // First pass with padding only
+
+ input.u.ui32 = htonl(pad4b);
+
+ if (!EVP_CipherUpdate(ctx, output.u.outbuf, &outlen, input.u.input, 16)) {
+ fprintf(stderr, "cryptopan.so: error encrypting: %s\n", ERR_reason_error_string(ERR_get_error()));
+ exit(1);
+ }
+ if (outlen != 16) {
+ fprintf(stderr, "cryptopan.so: error encrypted result is not 16 bytes\n");
+ exit(1);
+ }
+
+ orig ^= ntohl(output.u.ui32) & 0x80000000;
+ mask >>= 1;
+ mask |= 0x80000000;
+
+ for (pos = 1; pos < 32; pos++) {
+ input.u.ui32 = htonl(((pad4b << pos) | (pad4b >> (32 - pos))) ^ (orig & mask));
+
+ if (!EVP_CipherUpdate(ctx, output.u.outbuf, &outlen, input.u.input, 16)) {
+ fprintf(stderr, "cryptopan.so: error encrypting: %s\n", ERR_reason_error_string(ERR_get_error()));
+ exit(1);
+ }
+ if (outlen != 16) {
+ fprintf(stderr, "cryptopan.so: error encrypted result is not 16 bytes\n");
+ exit(1);
+ }
+
+ orig ^= (ntohl(output.u.ui32) & 0x80000000) >> pos;
+ mask >>= 1;
+ mask |= 0x80000000;
+ }
+
+ *in = htonl(orig);
+}
+#endif
+
+int cryptopan_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)
+{
+#ifdef USE_OPENSSL
+ 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((uint32_t*)&from->u.a4) : _encrypt((uint32_t*)&from->u.a4);
+ break;
+ case AF_INET6:
+ if (encrypt_v6) {
+ if (decrypt) {
+ _decrypt((uint32_t*)&from->u.a6);
+ _decrypt(((uint32_t*)&from->u.a6) + 1); // lgtm [cpp/suspicious-pointer-scaling]
+ _decrypt(((uint32_t*)&from->u.a6) + 2); // lgtm [cpp/suspicious-pointer-scaling]
+ _decrypt(((uint32_t*)&from->u.a6) + 3); // lgtm [cpp/suspicious-pointer-scaling]
+ } else {
+ _encrypt((uint32_t*)&from->u.a6);
+ _encrypt(((uint32_t*)&from->u.a6) + 1); // lgtm [cpp/suspicious-pointer-scaling]
+ _encrypt(((uint32_t*)&from->u.a6) + 2); // lgtm [cpp/suspicious-pointer-scaling]
+ _encrypt(((uint32_t*)&from->u.a6) + 3); // lgtm [cpp/suspicious-pointer-scaling]
+ }
+ 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((uint32_t*)&to->u.a4) : _encrypt((uint32_t*)&to->u.a4);
+ break;
+ case AF_INET6:
+ if (encrypt_v6) {
+ if (decrypt) {
+ _decrypt((uint32_t*)&to->u.a6);
+ _decrypt(((uint32_t*)&to->u.a6) + 1); // lgtm [cpp/suspicious-pointer-scaling]
+ _decrypt(((uint32_t*)&to->u.a6) + 2); // lgtm [cpp/suspicious-pointer-scaling]
+ _decrypt(((uint32_t*)&to->u.a6) + 3); // lgtm [cpp/suspicious-pointer-scaling]
+ } else {
+ _encrypt((uint32_t*)&to->u.a6);
+ _encrypt(((uint32_t*)&to->u.a6) + 1); // lgtm [cpp/suspicious-pointer-scaling]
+ _encrypt(((uint32_t*)&to->u.a6) + 2); // lgtm [cpp/suspicious-pointer-scaling]
+ _encrypt(((uint32_t*)&to->u.a6) + 3); // lgtm [cpp/suspicious-pointer-scaling]
+ }
+ break;
+ }
+ default:
+ to = 0;
+ break;
+ }
+ break;
+ }
+
+ if (cryptopan_set_iaddr && (from || to)) {
+ cryptopan_set_iaddr(from, to);
+ }
+#endif
+ return 0;
+}
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