fuzzer.c

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/*
 *   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: 3ca17f9601735631324c5429fbf6cd7bd7193a6e $
 *
 * @file src/bin/fuzzer.c
 * @brief Functions to fuzz protocol decoding
 *
 * @copyright 2019 Network RADIUS SAS (legal@networkradius.com)
 */
RCSID("$Id: 3ca17f9601735631324c5429fbf6cd7bd7193a6e $")
 
#include <freeradius-devel/util/dl.h>
#include <freeradius-devel/util/conf.h>
#include <freeradius-devel/util/dict.h>
#include <freeradius-devel/util/atexit.h>
#include <freeradius-devel/util/syserror.h>
#include <freeradius-devel/util/strerror.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 fr_dict_t                *dict = NULL;
 
extern fr_test_point_proto_decode_t XX_PROTOCOL_XX_tp_decode_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);
 
        /*
         *      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              *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);
 
        /*
         *      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);
 
        init = true;
 
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
        talloc_free(dict_dir_to_free);
        talloc_free(lib_dir_to_free);
#endif
 
        return 1;
}
 
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;
        fr_test_point_proto_decode_t *tp = &XX_PROTOCOL_XX_tp_decode_proto;
 
        fr_pair_list_init(&vps);
        if (!init) LLVMFuzzerInitialize(NULL, NULL);
 
        if (tp->test_ctx && (tp->test_ctx(&decode_ctx, NULL, dict) < 0)) {
                fr_perror("fuzzer: Failed initializing test point decode_ctx");
                fr_exit_now(EXIT_FAILURE);
        }
 
        tp->func(ctx, &vps, buf, len, decode_ctx);
        if (fr_debug_lvl > 3) fr_pair_list_debug(&vps);
 
        talloc_free(decode_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;
}