diff options
Diffstat (limited to 'custom_mutators/atnwalk/atnwalk.c')
| -rw-r--r-- | custom_mutators/atnwalk/atnwalk.c | 539 |
1 files changed, 539 insertions, 0 deletions
diff --git a/custom_mutators/atnwalk/atnwalk.c b/custom_mutators/atnwalk/atnwalk.c new file mode 100644 index 00000000..c3a2cd95 --- /dev/null +++ b/custom_mutators/atnwalk/atnwalk.c @@ -0,0 +1,539 @@ +#include "afl-fuzz.h" + +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <unistd.h> + +#define BUF_SIZE_INIT 4096 +#define SOCKET_NAME "./atnwalk.socket" + +// how many errors (e.g. timeouts) to tolerate until moving on to the next queue +// entry +#define ATNWALK_ERRORS_MAX 1 + +// how many execution timeouts to tolerate until moving on to the next queue +// entry +#define EXEC_TIMEOUT_MAX 2 + +// handshake constants +const uint8_t SERVER_ARE_YOU_ALIVE = 213; +const uint8_t SERVER_YES_I_AM_ALIVE = 42; + +// control bits +const uint8_t SERVER_CROSSOVER_BIT = 0b00000001; +const uint8_t SERVER_MUTATE_BIT = 0b00000010; +const uint8_t SERVER_DECODE_BIT = 0b00000100; +const uint8_t SERVER_ENCODE_BIT = 0b00001000; + +typedef struct atnwalk_mutator { + + afl_state_t *afl; + uint8_t atnwalk_error_count; + uint64_t prev_timeouts; + uint32_t prev_hits; + uint32_t stage_havoc_cur; + uint32_t stage_havoc_max; + uint32_t stage_splice_cur; + uint32_t stage_splice_max; + uint8_t *fuzz_buf; + size_t fuzz_size; + uint8_t *post_process_buf; + size_t post_process_size; + +} atnwalk_mutator_t; + +int read_all(int fd, uint8_t *buf, size_t buf_size) { + + int n; + size_t offset = 0; + while (offset < buf_size) { + + n = read(fd, buf + offset, buf_size - offset); + if (n == -1) { return 0; } + offset += n; + + } + + return 1; + +} + +int write_all(int fd, uint8_t *buf, size_t buf_size) { + + int n; + size_t offset = 0; + while (offset < buf_size) { + + n = write(fd, buf + offset, buf_size - offset); + if (n == -1) { return 0; } + offset += n; + + } + + return 1; + +} + +void put_uint32(uint8_t *buf, uint32_t val) { + + buf[0] = (uint8_t)(val >> 24); + buf[1] = (uint8_t)((val & 0x00ff0000) >> 16); + buf[2] = (uint8_t)((val & 0x0000ff00) >> 8); + buf[3] = (uint8_t)(val & 0x000000ff); + +} + +uint32_t to_uint32(uint8_t *buf) { + + uint32_t val = 0; + val |= (((uint32_t)buf[0]) << 24); + val |= (((uint32_t)buf[1]) << 16); + val |= (((uint32_t)buf[2]) << 8); + val |= ((uint32_t)buf[3]); + return val; + +} + +void put_uint64(uint8_t *buf, uint64_t val) { + + buf[0] = (uint8_t)(val >> 56); + buf[1] = (uint8_t)((val & 0x00ff000000000000) >> 48); + buf[2] = (uint8_t)((val & 0x0000ff0000000000) >> 40); + buf[3] = (uint8_t)((val & 0x000000ff00000000) >> 32); + buf[4] = (uint8_t)((val & 0x00000000ff000000) >> 24); + buf[5] = (uint8_t)((val & 0x0000000000ff0000) >> 16); + buf[6] = (uint8_t)((val & 0x000000000000ff00) >> 8); + buf[7] = (uint8_t)(val & 0x00000000000000ff); + +} + +/** + * Initialize this custom mutator + * + * @param[in] afl a pointer to the internal state object. Can be ignored for + * now. + * @param[in] seed A seed for this mutator - the same seed should always mutate + * in the same way. + * @return Pointer to the data object this custom mutator instance should use. + * There may be multiple instances of this mutator in one afl-fuzz run! + * Return NULL on error. + */ +atnwalk_mutator_t *afl_custom_init(afl_state_t *afl, unsigned int seed) { + + srand(seed); + atnwalk_mutator_t *data = + (atnwalk_mutator_t *)malloc(sizeof(atnwalk_mutator_t)); + if (!data) { + + perror("afl_custom_init alloc"); + return NULL; + + } + + data->afl = afl; + data->prev_hits = 0; + data->fuzz_buf = (uint8_t *)malloc(BUF_SIZE_INIT); + data->fuzz_size = BUF_SIZE_INIT; + data->post_process_buf = (uint8_t *)malloc(BUF_SIZE_INIT); + data->post_process_size = BUF_SIZE_INIT; + return data; + +} + +unsigned int afl_custom_fuzz_count(atnwalk_mutator_t *data, + const unsigned char *buf, size_t buf_size) { + + // afl_custom_fuzz_count is called exactly once before entering the + // 'stage-loop' for the current queue entry thus, we use it to reset the error + // count and to initialize stage variables (somewhat not intended by the API, + // but still better than rewriting the whole thing to have a custom mutator + // stage) + data->atnwalk_error_count = 0; + data->prev_timeouts = data->afl->total_tmouts; + + // it might happen that on the last execution of the splice stage a new path + // is found we need to fix that here and count it + if (data->prev_hits) { + + data->afl->stage_finds[STAGE_SPLICE] += + data->afl->queued_items + data->afl->saved_crashes - data->prev_hits; + + } + + data->prev_hits = data->afl->queued_items + data->afl->saved_crashes; + data->stage_havoc_cur = 0; + data->stage_splice_cur = 0; + + // 50% havoc, 50% splice + data->stage_havoc_max = data->afl->stage_max >> 1; + if (data->stage_havoc_max < HAVOC_MIN) { data->stage_havoc_max = HAVOC_MIN; } + data->stage_splice_max = data->stage_havoc_max; + return data->stage_havoc_max + data->stage_splice_max; + +} + +size_t fail_fatal(int fd_socket, uint8_t **out_buf) { + + if (fd_socket != -1) { close(fd_socket); } + *out_buf = NULL; + return 0; + +} + +size_t fail_gracefully(int fd_socket, atnwalk_mutator_t *data, uint8_t *buf, + size_t buf_size, uint8_t **out_buf) { + + if (fd_socket != -1) { close(fd_socket); } + data->atnwalk_error_count++; + if (data->atnwalk_error_count > ATNWALK_ERRORS_MAX) { + + data->afl->stage_max = data->afl->stage_cur; + + } + + *out_buf = buf; + return buf_size; + +} + +/** + * Perform custom mutations on a given input + * + * (Optional for now. Required in the future) + * + * @param[in] data pointer returned in afl_custom_init for this fuzz case + * @param[in] buf Pointer to input data to be mutated + * @param[in] buf_size Size of input data + * @param[out] out_buf the buffer we will work on. we can reuse *buf. NULL on + * error. + * @param[in] add_buf Buffer containing the additional test case + * @param[in] add_buf_size Size of the additional test case + * @param[in] max_size Maximum size of the mutated output. The mutation must not + * produce data larger than max_size. + * @return Size of the mutated output. + */ +size_t afl_custom_fuzz(atnwalk_mutator_t *data, uint8_t *buf, size_t buf_size, + uint8_t **out_buf, uint8_t *add_buf, size_t add_buf_size, + size_t max_size) { + + struct sockaddr_un addr; + int fd_socket; + uint8_t ctrl_buf[8]; + uint8_t wanted; + + // let's display what's going on in a nice way + if (data->stage_havoc_cur == 0) { + + data->afl->stage_name = (uint8_t *)"atnwalk - havoc"; + + } + + if (data->stage_havoc_cur == data->stage_havoc_max) { + + data->afl->stage_name = (uint8_t *)"atnwalk - splice"; + + } + + // increase the respective havoc or splice counters + if (data->stage_havoc_cur < data->stage_havoc_max) { + + data->stage_havoc_cur++; + data->afl->stage_cycles[STAGE_HAVOC]++; + + } else { + + // if there is nothing to splice, continue with havoc and skip splicing this + // time + if (data->afl->ready_for_splicing_count < 1) { + + data->stage_havoc_max = data->afl->stage_max; + data->stage_havoc_cur++; + data->afl->stage_cycles[STAGE_HAVOC]++; + + } else { + + data->stage_splice_cur++; + data->afl->stage_cycles[STAGE_SPLICE]++; + + } + + } + + // keep track of found new corpus seeds per stage + if (data->afl->queued_items + data->afl->saved_crashes > data->prev_hits) { + + if (data->stage_splice_cur <= 1) { + + data->afl->stage_finds[STAGE_HAVOC] += + data->afl->queued_items + data->afl->saved_crashes - data->prev_hits; + + } else { + + data->afl->stage_finds[STAGE_SPLICE] += + data->afl->queued_items + data->afl->saved_crashes - data->prev_hits; + + } + + } + + data->prev_hits = data->afl->queued_items + data->afl->saved_crashes; + + // check whether this input produces a lot of timeouts, if it does then + // abandon this queue entry + if (data->afl->total_tmouts - data->prev_timeouts >= EXEC_TIMEOUT_MAX) { + + data->afl->stage_max = data->afl->stage_cur; + return fail_gracefully(-1, data, buf, buf_size, out_buf); + + } + + // initialize the socket + fd_socket = socket(AF_UNIX, SOCK_STREAM, 0); + if (fd_socket == -1) { return fail_fatal(fd_socket, out_buf); } + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + strncpy(addr.sun_path, SOCKET_NAME, sizeof(addr.sun_path) - 1); + if (connect(fd_socket, (const struct sockaddr *)&addr, sizeof(addr)) == -1) { + + return fail_fatal(fd_socket, out_buf); + + } + + // ask whether the server is alive + ctrl_buf[0] = SERVER_ARE_YOU_ALIVE; + if (!write_all(fd_socket, ctrl_buf, 1)) { + + return fail_fatal(fd_socket, out_buf); + + } + + // see whether the server replies as expected + if (!read_all(fd_socket, ctrl_buf, 1) || + ctrl_buf[0] != SERVER_YES_I_AM_ALIVE) { + + return fail_fatal(fd_socket, out_buf); + + } + + // tell the server what we want to do + wanted = SERVER_MUTATE_BIT | SERVER_ENCODE_BIT; + + // perform a crossover if we are splicing + if (data->stage_splice_cur > 0) { wanted |= SERVER_CROSSOVER_BIT; } + + // tell the server what we want and how much data will be sent + ctrl_buf[0] = wanted; + put_uint32(ctrl_buf + 1, (uint32_t)buf_size); + if (!write_all(fd_socket, ctrl_buf, 5)) { + + return fail_fatal(fd_socket, out_buf); + + } + + // send the data to mutate and encode + if (!write_all(fd_socket, buf, buf_size)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + if (wanted & SERVER_CROSSOVER_BIT) { + + // since we requested crossover, we will first tell how much additional data + // is to be expected + put_uint32(ctrl_buf, (uint32_t)add_buf_size); + if (!write_all(fd_socket, ctrl_buf, 4)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + // send the additional data for crossover + if (!write_all(fd_socket, add_buf, add_buf_size)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + // lastly, a seed is required for crossover so send one + put_uint64(ctrl_buf, (uint64_t)rand()); + if (!write_all(fd_socket, ctrl_buf, 8)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + } + + // since we requested mutation, we need to provide a seed for that + put_uint64(ctrl_buf, (uint64_t)rand()); + if (!write_all(fd_socket, ctrl_buf, 8)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + // obtain the required buffer size for the data that will be returned + if (!read_all(fd_socket, ctrl_buf, 4)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + size_t new_size = (size_t)to_uint32(ctrl_buf); + + // if the data is too large then we ignore this round + if (new_size > max_size) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + if (new_size > buf_size) { + + // buf is too small, need to use data->fuzz_buf, let's see whether we need + // to reallocate + if (new_size > data->fuzz_size) { + + data->fuzz_size = new_size << 1; + data->fuzz_buf = (uint8_t *)realloc(data->fuzz_buf, data->fuzz_size); + + } + + *out_buf = data->fuzz_buf; + + } else { + + // new_size fits into buf, so re-use it + *out_buf = buf; + + } + + // obtain the encoded data + if (!read_all(fd_socket, *out_buf, new_size)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + close(fd_socket); + return new_size; + +} + +/** + * A post-processing function to use right before AFL writes the test case to + * disk in order to execute the target. + * + * (Optional) If this functionality is not needed, simply don't define this + * function. + * + * @param[in] data pointer returned in afl_custom_init for this fuzz case + * @param[in] buf Buffer containing the test case to be executed + * @param[in] buf_size Size of the test case + * @param[out] out_buf Pointer to the buffer containing the test case after + * processing. External library should allocate memory for out_buf. + * The buf pointer may be reused (up to the given buf_size); + * @return Size of the output buffer after processing or the needed amount. + * A return of 0 indicates an error. + */ +size_t afl_custom_post_process(atnwalk_mutator_t *data, uint8_t *buf, + size_t buf_size, uint8_t **out_buf) { + + struct sockaddr_un addr; + int fd_socket; + uint8_t ctrl_buf[8]; + + // initialize the socket + fd_socket = socket(AF_UNIX, SOCK_STREAM, 0); + if (fd_socket == -1) { return fail_fatal(fd_socket, out_buf); } + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + strncpy(addr.sun_path, SOCKET_NAME, sizeof(addr.sun_path) - 1); + if (connect(fd_socket, (const struct sockaddr *)&addr, sizeof(addr)) == -1) { + + return fail_fatal(fd_socket, out_buf); + + } + + // ask whether the server is alive + ctrl_buf[0] = SERVER_ARE_YOU_ALIVE; + if (!write_all(fd_socket, ctrl_buf, 1)) { + + return fail_fatal(fd_socket, out_buf); + + } + + // see whether the server replies as expected + if (!read_all(fd_socket, ctrl_buf, 1) || + ctrl_buf[0] != SERVER_YES_I_AM_ALIVE) { + + return fail_fatal(fd_socket, out_buf); + + } + + // tell the server what we want and how much data will be sent + ctrl_buf[0] = SERVER_DECODE_BIT; + put_uint32(ctrl_buf + 1, (uint32_t)buf_size); + if (!write_all(fd_socket, ctrl_buf, 5)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + // send the data to decode + if (!write_all(fd_socket, buf, buf_size)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + // obtain the required buffer size for the data that will be returned + if (!read_all(fd_socket, ctrl_buf, 4)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + size_t new_size = (size_t)to_uint32(ctrl_buf); + + // need to use data->post_process_buf, let's see whether we need to reallocate + if (new_size > data->post_process_size) { + + data->post_process_size = new_size << 1; + data->post_process_buf = + (uint8_t *)realloc(data->post_process_buf, data->post_process_size); + + } + + *out_buf = data->post_process_buf; + + // obtain the decoded data + if (!read_all(fd_socket, *out_buf, new_size)) { + + return fail_gracefully(fd_socket, data, buf, buf_size, out_buf); + + } + + close(fd_socket); + return new_size; + +} + +/** + * Deinitialize everything + * + * @param data The data ptr from afl_custom_init + */ +void afl_custom_deinit(atnwalk_mutator_t *data) { + + free(data->fuzz_buf); + free(data->post_process_buf); + free(data); + +} + |