/*

 *   This program is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation; either version 2 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program; if not, write to the Free Software

 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA

 */

/**

 * $Id: b8879c232e3daf0c911397f829066c0502315d5b $

 *

 * @file src/bin/fuzzer.c

 * @brief Functions to fuzz protocol decoding

 *

 * @copyright 2019 Network RADIUS SAS (legal@networkradius.com)

 */

RCSID("$Id: b8879c232e3daf0c911397f829066c0502315d5b $")

#include <freeradius-devel/util/dl.h>

#include <freeradius-devel/util/conf.h>

#include <freeradius-devel/util/dict.h>

#include <freeradius-devel/util/proto.h>

#include <freeradius-devel/util/syserror.h>

#include <freeradius-devel/io/test_point.h>

/*

 *  Run from the source directory via:

 *

 *  ./build/make/jlibtool --mode=execute ./build/bin/local/fuzzer_radius -D share/dictionary /path/to/corpus/directory/

 */

static bool     init = false;

static dl_t     *dl = NULL;

static dl_loader_t    *dl_loader;

static fr_dict_protocol_t *dl_proto;

static TALLOC_CTX   *autofree = NULL;

static bool     do_encode = false;

static fr_dict_t    *dict = NULL;

extern fr_test_point_proto_decode_t dns_tp_decode_proto;

extern fr_test_point_proto_encode_t dns_tp_encode_proto;

int LLVMFuzzerInitialize(int *argc, char ***argv);

int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len);

static void exitHandler(void)

{

  if (dl_proto && dl_proto->free) dl_proto->free();

  fr_dict_free(&dict, __FILE__);

  if (dl && dl->handle) {

    dlclose(dl->handle);

    dl->handle = NULL;

  }

  talloc_free(dl_loader);

  talloc_free(autofree);

  /*

   *  Ensure our atexit handlers run before any other

   *  atexit handlers registered by third party libraries.

   */

  fr_atexit_global_trigger_all();

}

static inline

fr_dict_protocol_t *fuzzer_dict_init(void *dl_handle, char const *proto)

{

  char      buffer[256];

  fr_dict_protocol_t  *our_dl_proto;

  snprintf(buffer, sizeof(buffer), "libfreeradius_%s_dict_protocol", proto);

  our_dl_proto = dlsym(dl_handle, buffer);

  if (our_dl_proto && our_dl_proto->init && (our_dl_proto->init() < 0)) {

    fr_perror("fuzzer: Failed initializing library %s", buffer);

    fr_exit_now(EXIT_FAILURE);

  }

  return our_dl_proto;

}

int LLVMFuzzerInitialize(int *argc, char ***argv)

{

  char const    *lib_dir    = getenv("FR_LIBRARY_PATH");

  char const    *proto      = getenv("FR_LIBRARY_FUZZ_PROTOCOL");

  char const    *dict_dir = getenv("FR_DICTIONARY_DIR");

  char const    *debug_lvl_str  = getenv("FR_DEBUG_LVL");

  char const    *panic_action = getenv("PANIC_ACTION");

  char const    *p;

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

  char      *dict_dir_to_free = NULL;

  char      *lib_dir_to_free = NULL;

#endif

  if (!argc || !argv || !*argv) return -1; /* shut up clang scan */

  if (debug_lvl_str) {

    fr_debug_lvl = atoi(debug_lvl_str);

    if (fr_debug_lvl) fr_time_start();

  }

  /*

   *  Setup atexit handlers to free any thread local

   *  memory on exit

   */

  fr_atexit_global_setup();

  /*

   *  Initialise the talloc fault handlers.

   */

  fr_talloc_fault_setup();

  /*

   *  Initialise the error stack _before_ we run any

   *  tests so there's no chance of the memory

   *  appearing as a leak the first time an error

   *  is generated.

   */

  fr_strerror_const("fuzz"); /* allocate the pools */

  fr_strerror_clear(); /* clears the message, leaves the pools */

  /*

   *  Setup our own internal atexit handler

   */

  if (atexit(exitHandler)) {

    fr_perror("fuzzer: Failed to register exit handler: %s", fr_syserror(errno));

    fr_exit_now(EXIT_FAILURE);

  }

  /*

   *  Get the name from the binary name of fuzzer_foo

   */

  if (!proto) {

    proto = strrchr((*argv)[0], '_');

    if (proto) proto++;

  }

  /*

   *  Look for -D dir

   *

   *  If found, nuke it from the argument list.

   */

  if (!dict_dir) {

    int i, j;

    for (i = 0; i < *argc - 1; i++) {

      p = (*argv)[i];

      if ((p[0] == '-') && (p[1] == 'D')) {

        dict_dir = (*argv)[i + 1];

        for (j = i + 2; j < *argc; i++, j++) {

          (*argv)[i] = (*argv)[j];

        }

        *argc -= 2;

        break;

      }

    }

  }

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

  /*

   *  oss-fuzz puts the dictionaries, etc. into subdirectories named after the location of the

   *  binary.  So we find the directory of the binary, and append "/dict" or "/lib" to find

   *  dictionaries and libraries.

   */

  p = strrchr((*argv)[0], '/');

  if (p) {

    if (!dict_dir) {

      dict_dir = dict_dir_to_free = talloc_asprintf(NULL, "%.*s/dict", (int) (p - (*argv)[0]), (*argv)[0]);

      if (!dict_dir_to_free) fr_exit_now(EXIT_FAILURE);

    }

    if (!lib_dir) {

      lib_dir = lib_dir_to_free = talloc_asprintf(NULL, "%.*s/lib", (int) (p - (*argv)[0]), (*argv)[0]);

      if (!lib_dir_to_free) fr_exit_now(EXIT_FAILURE);

    }

  }

#endif

  if (!dict_dir) dict_dir = DICTDIR;

  if (!lib_dir) lib_dir = LIBDIR;

  /*

   *  Set the global search path for all dynamic libraries we load.

   */

  if (dl_search_global_path_set(lib_dir) < 0) {

    fr_perror("fuzzer: Failed setting library path");

    fr_exit_now(EXIT_FAILURE);

  }

  /*

   *  When jobs=N is specified the fuzzer spawns worker processes via

   *  a shell. We have removed any -D dictdir argument that were

   *  supplied, so we pass it to our children via the environment.

   */

  if (setenv("FR_DICTIONARY_DIR", dict_dir, 1)) {

    fprintf(stderr, "Failed to set FR_DICTIONARY_DIR env variable\n");

    fr_exit_now(EXIT_FAILURE);

  }

  if (!fr_dict_global_ctx_init(NULL, true, dict_dir)) {

    fr_perror("dict_global");

    fr_exit_now(EXIT_FAILURE);

  }

  if (fr_dict_internal_afrom_file(&dict, FR_DICTIONARY_INTERNAL_DIR, __FILE__) < 0) {

    fr_perror("fuzzer: Failed initializing internal dictionary");

    fr_exit_now(EXIT_FAILURE);

  }

  if (!proto) {

    fr_perror("Failed to find protocol for fuzzer");

    fr_exit_now(EXIT_FAILURE);

  }

  /*

   *  Disable hostname lookups, so we don't produce spurious DNS

   *  queries, and there's no chance of spurious failures if

   *  it takes a long time to get a response.

   */

  fr_hostname_lookups = fr_reverse_lookups = false;

  /*

   *  Search in our symbol space first.  We may have been dynamically

   *  or statically linked to the library we're fuzzing...

   */

  dl_proto = fuzzer_dict_init(RTLD_DEFAULT, proto);

  autofree = talloc_autofree_context();

  if (fr_fault_setup(autofree, panic_action, (*argv)[0]) < 0) {

    fr_perror("Failed initializing fault handler");

    fr_exit_now(EXIT_FAILURE);

  }

  init = true;

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION

  talloc_free(dict_dir_to_free);

  talloc_free(lib_dir_to_free);

#endif

  return 1;

}

static uint8_t encoded_data[65536];

int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len)

{

  TALLOC_CTX *   ctx = talloc_init_const("fuzzer");

  fr_pair_list_t vps;

  void *decode_ctx = NULL;

  void *encode_ctx = NULL;

  fr_test_point_proto_decode_t *tp_decode = &dns_tp_decode_proto;

  fr_test_point_proto_encode_t *tp_encode = &dns_tp_encode_proto;

  fr_pair_list_init(&vps);

  if (!init) LLVMFuzzerInitialize(NULL, NULL);

  if (tp_decode->test_ctx && (tp_decode->test_ctx(&decode_ctx, NULL, dict, NULL) < 0)) {

    fr_perror("fuzzer: Failed initializing test point decode_ctx");

    fr_exit_now(EXIT_FAILURE);

  }

  if (tp_encode->test_ctx && (tp_encode->test_ctx(&encode_ctx, NULL, dict, NULL) < 0)) {

    fr_perror("fuzzer: Failed initializing test point encode_ctx");

    fr_exit_now(EXIT_FAILURE);

  }

  if (fr_debug_lvl > 3) {

    FR_PROTO_TRACE("Fuzzer input");

    FR_PROTO_HEX_DUMP(buf, len, "");

  }

  /*

   *  Decode the input, and print the resulting data if we

   *  decoded it successfully.

   *

   *  If we have successfully decoded the data, then encode

   *  it again, too.

   */

  if (tp_decode->func(ctx, &vps, buf, len, decode_ctx) > 0) {

    PAIR_LIST_VERIFY_WITH_CTX(ctx, &vps);

    if (fr_debug_lvl > 3) fr_pair_list_debug(stderr, &vps);

    if (do_encode) (void) tp_encode->func(ctx, &vps, encoded_data, sizeof(encoded_data), encode_ctx);

  }

  talloc_free(decode_ctx);

  talloc_free(encode_ctx);

  talloc_free(ctx);

  /*

   *  Clear error messages from the run.  Clearing these

   *  keeps malloc/free balanced, which helps to avoid the

   *  fuzzers leak heuristics from firing.

   */

  fr_strerror_clear();

  return 0;

}