diff options
| -rw-r--r-- | custom_mutators/examples/custom_mutator_helpers.h | 342 | ||||
| -rw-r--r-- | custom_mutators/examples/custom_send.c | 8 | ||||
| -rw-r--r-- | custom_mutators/examples/example.c | 116 | ||||
| -rw-r--r-- | custom_mutators/examples/post_library_gif.so.c | 53 | ||||
| -rw-r--r-- | custom_mutators/examples/post_library_png.so.c | 24 | ||||
| -rw-r--r-- | custom_mutators/examples/simple_example.c | 28 | ||||
| -rw-r--r-- | docs/Changelog.md | 1 |
7 files changed, 73 insertions, 499 deletions
diff --git a/custom_mutators/examples/custom_mutator_helpers.h b/custom_mutators/examples/custom_mutator_helpers.h deleted file mode 100644 index 62e6efba..00000000 --- a/custom_mutators/examples/custom_mutator_helpers.h +++ /dev/null @@ -1,342 +0,0 @@ -#ifndef CUSTOM_MUTATOR_HELPERS -#define CUSTOM_MUTATOR_HELPERS - -#include "config.h" -#include "types.h" -#include <stdlib.h> - -#define INITIAL_GROWTH_SIZE (64) - -#define RAND_BELOW(limit) (rand() % (limit)) - -/* Use in a struct: creates a name_buf and a name_size variable. */ -#define BUF_VAR(type, name) \ - type * name##_buf; \ - size_t name##_size; -/* this fills in `&structptr->something_buf, &structptr->something_size`. */ -#define BUF_PARAMS(struct, name) \ - (void **)&struct->name##_buf, &struct->name##_size - -typedef struct { - -} afl_t; - -static void surgical_havoc_mutate(u8 *out_buf, s32 begin, s32 end) { - - static s8 interesting_8[] = {INTERESTING_8}; - static s16 interesting_16[] = {INTERESTING_8, INTERESTING_16}; - static s32 interesting_32[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32}; - - switch (RAND_BELOW(12)) { - - case 0: { - - /* Flip a single bit somewhere. Spooky! */ - - s32 bit_idx = ((RAND_BELOW(end - begin) + begin) << 3) + RAND_BELOW(8); - - out_buf[bit_idx >> 3] ^= 128 >> (bit_idx & 7); - - break; - - } - - case 1: { - - /* Set byte to interesting value. */ - - u8 val = interesting_8[RAND_BELOW(sizeof(interesting_8))]; - out_buf[(RAND_BELOW(end - begin) + begin)] = val; - - break; - - } - - case 2: { - - /* Set word to interesting value, randomly choosing endian. */ - - if (end - begin < 2) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 1) break; - - switch (RAND_BELOW(2)) { - - case 0: - *(u16 *)(out_buf + byte_idx) = - interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)]; - break; - case 1: - *(u16 *)(out_buf + byte_idx) = - SWAP16(interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)]); - break; - - } - - break; - - } - - case 3: { - - /* Set dword to interesting value, randomly choosing endian. */ - - if (end - begin < 4) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 3) break; - - switch (RAND_BELOW(2)) { - - case 0: - *(u32 *)(out_buf + byte_idx) = - interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]; - break; - case 1: - *(u32 *)(out_buf + byte_idx) = - SWAP32(interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]); - break; - - } - - break; - - } - - case 4: { - - /* Set qword to interesting value, randomly choosing endian. */ - - if (end - begin < 8) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 7) break; - - switch (RAND_BELOW(2)) { - - case 0: - *(u64 *)(out_buf + byte_idx) = - (s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]; - break; - case 1: - *(u64 *)(out_buf + byte_idx) = SWAP64( - (s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]); - break; - - } - - break; - - } - - case 5: { - - /* Randomly subtract from byte. */ - - out_buf[(RAND_BELOW(end - begin) + begin)] -= 1 + RAND_BELOW(ARITH_MAX); - - break; - - } - - case 6: { - - /* Randomly add to byte. */ - - out_buf[(RAND_BELOW(end - begin) + begin)] += 1 + RAND_BELOW(ARITH_MAX); - - break; - - } - - case 7: { - - /* Randomly subtract from word, random endian. */ - - if (end - begin < 2) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 1) break; - - if (RAND_BELOW(2)) { - - *(u16 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX); - - } else { - - u16 num = 1 + RAND_BELOW(ARITH_MAX); - - *(u16 *)(out_buf + byte_idx) = - SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) - num); - - } - - break; - - } - - case 8: { - - /* Randomly add to word, random endian. */ - - if (end - begin < 2) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 1) break; - - if (RAND_BELOW(2)) { - - *(u16 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX); - - } else { - - u16 num = 1 + RAND_BELOW(ARITH_MAX); - - *(u16 *)(out_buf + byte_idx) = - SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) + num); - - } - - break; - - } - - case 9: { - - /* Randomly subtract from dword, random endian. */ - - if (end - begin < 4) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 3) break; - - if (RAND_BELOW(2)) { - - *(u32 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX); - - } else { - - u32 num = 1 + RAND_BELOW(ARITH_MAX); - - *(u32 *)(out_buf + byte_idx) = - SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) - num); - - } - - break; - - } - - case 10: { - - /* Randomly add to dword, random endian. */ - - if (end - begin < 4) break; - - s32 byte_idx = (RAND_BELOW(end - begin) + begin); - - if (byte_idx >= end - 3) break; - - if (RAND_BELOW(2)) { - - *(u32 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX); - - } else { - - u32 num = 1 + RAND_BELOW(ARITH_MAX); - - *(u32 *)(out_buf + byte_idx) = - SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) + num); - - } - - break; - - } - - case 11: { - - /* Just set a random byte to a random value. Because, - why not. We use XOR with 1-255 to eliminate the - possibility of a no-op. */ - - out_buf[(RAND_BELOW(end - begin) + begin)] ^= 1 + RAND_BELOW(255); - - break; - - } - - } - -} - -/* This function calculates the next power of 2 greater or equal its argument. - @return The rounded up power of 2 (if no overflow) or 0 on overflow. -*/ -static inline size_t next_pow2(size_t in) { - - if (in == 0 || in > (size_t)-1) - return 0; /* avoid undefined behaviour under-/overflow */ - size_t out = in - 1; - out |= out >> 1; - out |= out >> 2; - out |= out >> 4; - out |= out >> 8; - out |= out >> 16; - return out + 1; - -} - -/* This function makes sure *size is > size_needed after call. - It will realloc *buf otherwise. - *size will grow exponentially as per: - https://blog.mozilla.org/nnethercote/2014/11/04/please-grow-your-buffers-exponentially/ - Will return NULL and free *buf if size_needed is <1 or realloc failed. - @return For convenience, this function returns *buf. - */ -static inline void *maybe_grow(void **buf, size_t *size, size_t size_needed) { - - /* No need to realloc */ - if (likely(size_needed && *size >= size_needed)) return *buf; - - /* No initial size was set */ - if (size_needed < INITIAL_GROWTH_SIZE) size_needed = INITIAL_GROWTH_SIZE; - - /* grow exponentially */ - size_t next_size = next_pow2(size_needed); - - /* handle overflow */ - if (!next_size) { next_size = size_needed; } - - /* alloc */ - *buf = realloc(*buf, next_size); - *size = *buf ? next_size : 0; - - return *buf; - -} - -/* Swaps buf1 ptr and buf2 ptr, as well as their sizes */ -static inline void afl_swap_bufs(void **buf1, size_t *size1, void **buf2, - size_t *size2) { - - void * scratch_buf = *buf1; - size_t scratch_size = *size1; - *buf1 = *buf2; - *size1 = *size2; - *buf2 = scratch_buf; - *size2 = scratch_size; - -} - -#undef INITIAL_GROWTH_SIZE - -#endif - diff --git a/custom_mutators/examples/custom_send.c b/custom_mutators/examples/custom_send.c index 7de72819..9cc4b160 100644 --- a/custom_mutators/examples/custom_send.c +++ b/custom_mutators/examples/custom_send.c @@ -10,21 +10,21 @@ // afl-fuzz -i in -o out -- ./test-instr -f /tmp/foo // -#include "custom_mutator_helpers.h" - #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> +#include "afl-fuzz.h" + typedef struct my_mutator { - afl_t *afl; + afl_state_t *afl; } my_mutator_t; -my_mutator_t *afl_custom_init(afl_t *afl, unsigned int seed) { +my_mutator_t *afl_custom_init(afl_state_t *afl, unsigned int seed) { my_mutator_t *data = calloc(1, sizeof(my_mutator_t)); if (!data) { diff --git a/custom_mutators/examples/example.c b/custom_mutators/examples/example.c index e680ec8e..42c7469c 100644 --- a/custom_mutators/examples/example.c +++ b/custom_mutators/examples/example.c @@ -7,7 +7,7 @@ */ // You need to use -I/path/to/AFLplusplus/include -I. -#include "custom_mutator_helpers.h" +#include "afl-fuzz.h" #include <stdint.h> #include <stdlib.h> @@ -26,19 +26,14 @@ static const char *commands[] = { typedef struct my_mutator { - afl_t *afl; + afl_state_t *afl; // any additional data here! size_t trim_size_current; int trimmming_steps; int cur_step; - // Reused buffers: - BUF_VAR(u8, fuzz); - BUF_VAR(u8, data); - BUF_VAR(u8, havoc); - BUF_VAR(u8, trim); - BUF_VAR(u8, post_process); + u8 *mutated_out, *post_process_buf, *trim_buf; } my_mutator_t; @@ -53,7 +48,7 @@ typedef struct my_mutator { * There may be multiple instances of this mutator in one afl-fuzz run! * Return NULL on error. */ -my_mutator_t *afl_custom_init(afl_t *afl, unsigned int seed) { +my_mutator_t *afl_custom_init(afl_state_t *afl, unsigned int seed) { srand(seed); // needed also by surgical_havoc_mutate() @@ -65,6 +60,27 @@ my_mutator_t *afl_custom_init(afl_t *afl, unsigned int seed) { } + if ((data->mutated_out = (u8 *)malloc(MAX_FILE)) == NULL) { + + perror("afl_custom_init malloc"); + return NULL; + + } + + if ((data->post_process_buf = (u8 *)malloc(MAX_FILE)) == NULL) { + + perror("afl_custom_init malloc"); + return NULL; + + } + + if ((data->trim_buf = (u8 *)malloc(MAX_FILE)) == NULL) { + + perror("afl_custom_init malloc"); + return NULL; + + } + data->afl = afl; return data; @@ -96,31 +112,14 @@ size_t afl_custom_fuzz(my_mutator_t *data, uint8_t *buf, size_t buf_size, // the fuzzer size_t mutated_size = DATA_SIZE <= max_size ? DATA_SIZE : max_size; - // maybe_grow is optimized to be quick for reused buffers. - u8 *mutated_out = maybe_grow(BUF_PARAMS(data, fuzz), mutated_size); - if (!mutated_out) { - - *out_buf = NULL; - perror("custom mutator allocation (maybe_grow)"); - return 0; /* afl-fuzz will very likely error out after this. */ - - } + memcpy(data->mutated_out, buf, buf_size); // Randomly select a command string to add as a header to the packet - memcpy(mutated_out, commands[rand() % 3], 3); + memcpy(data->mutated_out, commands[rand() % 3], 3); - // Mutate the payload of the packet - int i; - for (i = 0; i < 8; ++i) { + if (mutated_size > max_size) { mutated_size = max_size; } - // Randomly perform one of the (no len modification) havoc mutations - surgical_havoc_mutate(mutated_out, 3, mutated_size); - - } - - if (max_size > mutated_size) { mutated_size = max_size; } - - *out_buf = mutated_out; + *out_buf = data->mutated_out; return mutated_size; } @@ -144,24 +143,16 @@ size_t afl_custom_fuzz(my_mutator_t *data, uint8_t *buf, size_t buf_size, size_t afl_custom_post_process(my_mutator_t *data, uint8_t *buf, size_t buf_size, uint8_t **out_buf) { - uint8_t *post_process_buf = - maybe_grow(BUF_PARAMS(data, post_process), buf_size + 5); - if (!post_process_buf) { + if (buf_size + 5 > MAX_FILE) { buf_size = MAX_FILE - 5; } - perror("custom mutator realloc failed."); - *out_buf = NULL; - return 0; + memcpy(data->post_process_buf + 5, buf, buf_size); + data->post_process_buf[0] = 'A'; + data->post_process_buf[1] = 'F'; + data->post_process_buf[2] = 'L'; + data->post_process_buf[3] = '+'; + data->post_process_buf[4] = '+'; - } - - memcpy(post_process_buf + 5, buf, buf_size); - post_process_buf[0] = 'A'; - post_process_buf[1] = 'F'; - post_process_buf[2] = 'L'; - post_process_buf[3] = '+'; - post_process_buf[4] = '+'; - - *out_buf = post_process_buf; + *out_buf = data->post_process_buf; return buf_size + 5; @@ -197,13 +188,6 @@ int32_t afl_custom_init_trim(my_mutator_t *data, uint8_t *buf, data->cur_step = 0; - if (!maybe_grow(BUF_PARAMS(data, trim), buf_size)) { - - perror("init_trim grow"); - return -1; - - } - memcpy(data->trim_buf, buf, buf_size); data->trim_size_current = buf_size; @@ -284,27 +268,11 @@ int32_t afl_custom_post_trim(my_mutator_t *data, int success) { size_t afl_custom_havoc_mutation(my_mutator_t *data, u8 *buf, size_t buf_size, u8 **out_buf, size_t max_size) { - if (buf_size == 0) { - - *out_buf = maybe_grow(BUF_PARAMS(data, havoc), 1); - if (!*out_buf) { - - perror("custom havoc: maybe_grow"); - return 0; - - } + *out_buf = buf; // in-place mutation - **out_buf = rand() % 256; - buf_size = 1; - - } else { - - // We reuse buf here. It's legal and faster. - *out_buf = buf; - - } + if (buf_size <= sizeof(size_t)) { return buf_size; } - size_t victim = rand() % buf_size; + size_t victim = rand() % (buf_size - sizeof(size_t)); (*out_buf)[victim] += rand() % 10; return buf_size; @@ -371,9 +339,7 @@ uint8_t afl_custom_queue_new_entry(my_mutator_t *data, void afl_custom_deinit(my_mutator_t *data) { free(data->post_process_buf); - free(data->havoc_buf); - free(data->data_buf); - free(data->fuzz_buf); + free(data->mutated_out); free(data->trim_buf); free(data); diff --git a/custom_mutators/examples/post_library_gif.so.c b/custom_mutators/examples/post_library_gif.so.c index 3cb018a6..6737c627 100644 --- a/custom_mutators/examples/post_library_gif.so.c +++ b/custom_mutators/examples/post_library_gif.so.c @@ -45,9 +45,8 @@ 1) If you don't want to modify the test case, simply set `*out_buf = in_buf` and return the original `len`. - NOTE: the following is currently NOT true, we abort in this case! 2) If you want to skip this test case altogether and have AFL generate a - new one, return 0 or set `*out_buf = NULL`. + new one, return 0. Use this sparingly - it's faster than running the target program with patently useless inputs, but still wastes CPU time. @@ -59,8 +58,6 @@ Note that the buffer will *not* be freed for you. To avoid memory leaks, you need to free it or reuse it on subsequent calls (as shown below). - *** Feel free to reuse the original 'in_buf' BUFFER and return it. *** - Alright. The example below shows a simple postprocessor that tries to make sure that all input files start with "GIF89a". @@ -72,7 +69,7 @@ #include <stdio.h> #include <stdlib.h> #include <string.h> -#include "alloc-inl.h" +#include "afl-fuzz.h" /* Header that must be present at the beginning of every test case: */ @@ -80,8 +77,7 @@ typedef struct post_state { - unsigned char *buf; - size_t size; + size_t size; } post_state_t; @@ -95,15 +91,6 @@ void *afl_custom_init(void *afl) { } - state->buf = calloc(sizeof(unsigned char), 4096); - if (!state->buf) { - - free(state); - perror("calloc"); - return NULL; - - } - return state; } @@ -113,6 +100,10 @@ void *afl_custom_init(void *afl) { size_t afl_custom_post_process(post_state_t *data, unsigned char *in_buf, unsigned int len, unsigned char **out_buf) { + /* we do in-place modification as we do not increase the size */ + + *out_buf = in_buf; + /* Skip execution altogether for buffers shorter than 6 bytes (just to show how it's done). We can trust len to be sane. */ @@ -120,34 +111,7 @@ size_t afl_custom_post_process(post_state_t *data, unsigned char *in_buf, /* Do nothing for buffers that already start with the expected header. */ - if (!memcmp(in_buf, HEADER, strlen(HEADER))) { - - *out_buf = in_buf; - return len; - - } - - /* Allocate memory for new buffer, reusing previous allocation if - possible. Note we have to use afl-fuzz's own realloc! - We use afl_realloc because it is effective. - You can also work within in_buf, and assign it to *out_buf. */ - - *out_buf = afl_realloc(out_buf, len); - - /* If we're out of memory, the most graceful thing to do is to return the - original buffer and give up on modifying it. Let AFL handle OOM on its - own later on. */ - - if (!*out_buf) { - - *out_buf = in_buf; - return len; - - } - - if (len > strlen(HEADER)) - memcpy(*out_buf + strlen(HEADER), in_buf + strlen(HEADER), - len - strlen(HEADER)); + if (!memcmp(in_buf, HEADER, strlen(HEADER))) { return len; } /* Insert the new header. */ @@ -162,7 +126,6 @@ size_t afl_custom_post_process(post_state_t *data, unsigned char *in_buf, /* Gets called afterwards */ void afl_custom_deinit(post_state_t *data) { - free(data->buf); free(data); } diff --git a/custom_mutators/examples/post_library_png.so.c b/custom_mutators/examples/post_library_png.so.c index cd65b1bc..652da497 100644 --- a/custom_mutators/examples/post_library_png.so.c +++ b/custom_mutators/examples/post_library_png.so.c @@ -30,7 +30,7 @@ #include <string.h> #include <zlib.h> #include <arpa/inet.h> -#include "alloc-inl.h" +#include "afl-fuzz.h" /* A macro to round an integer up to 4 kB. */ @@ -53,7 +53,7 @@ void *afl_custom_init(void *afl) { } - state->buf = calloc(sizeof(unsigned char), 4096); + state->buf = calloc(sizeof(unsigned char), MAX_FILE); if (!state->buf) { free(state); @@ -80,21 +80,7 @@ size_t afl_custom_post_process(post_state_t *data, const unsigned char *in_buf, } - /* This is not a good way to do it, if you do not need to grow the buffer - then just work with in_buf instead for speed reasons. - But we want to show how to grow a buffer, so this is how it's done: */ - - unsigned int pos = 8; - unsigned char *new_buf = afl_realloc(out_buf, UP4K(len)); - - if (!new_buf) { - - *out_buf = in_buf; - return len; - - } - - memcpy(new_buf, in_buf, len); + unsigned int pos = 8; /* Minimum size of a zero-length PNG chunk is 12 bytes; if we don't have that, we can bail out. */ @@ -124,7 +110,7 @@ size_t afl_custom_post_process(post_state_t *data, const unsigned char *in_buf, if (real_cksum != file_cksum) { - *(uint32_t *)(new_buf + pos + 8 + chunk_len) = real_cksum; + *(uint32_t *)(data->buf + pos + 8 + chunk_len) = real_cksum; } @@ -134,7 +120,7 @@ size_t afl_custom_post_process(post_state_t *data, const unsigned char *in_buf, } - *out_buf = new_buf; + *out_buf = data->buf; return len; } diff --git a/custom_mutators/examples/simple_example.c b/custom_mutators/examples/simple_example.c index d888ec1f..2c0abe29 100644 --- a/custom_mutators/examples/simple_example.c +++ b/custom_mutators/examples/simple_example.c @@ -1,6 +1,6 @@ // This simple example just creates random buffer <= 100 filled with 'A' // needs -I /path/to/AFLplusplus/include -#include "custom_mutator_helpers.h" +#include "afl-fuzz.h" #include <stdint.h> #include <stdlib.h> @@ -13,14 +13,14 @@ typedef struct my_mutator { - afl_t *afl; + afl_state_t *afl; // Reused buffers: - BUF_VAR(u8, fuzz); + u8 *fuzz_buf; } my_mutator_t; -my_mutator_t *afl_custom_init(afl_t *afl, unsigned int seed) { +my_mutator_t *afl_custom_init(afl_state_t *afl, unsigned int seed) { srand(seed); my_mutator_t *data = calloc(1, sizeof(my_mutator_t)); @@ -31,6 +31,14 @@ my_mutator_t *afl_custom_init(afl_t *afl, unsigned int seed) { } + data->fuzz_buf = (u8 *)malloc(MAX_FILE); + if (!data->fuzz_buf) { + + perror("afl_custom_init malloc"); + return NULL; + + } + data->afl = afl; return data; @@ -44,18 +52,10 @@ size_t afl_custom_fuzz(my_mutator_t *data, uint8_t *buf, size_t buf_size, int size = (rand() % 100) + 1; if (size > max_size) size = max_size; - u8 *mutated_out = maybe_grow(BUF_PARAMS(data, fuzz), size); - if (!mutated_out) { - - *out_buf = NULL; - perror("custom mutator allocation (maybe_grow)"); - return 0; /* afl-fuzz will very likely error out after this. */ - - } - memset(mutated_out, _FIXED_CHAR, size); + memset(data->fuzz_buf, _FIXED_CHAR, size); - *out_buf = mutated_out; + *out_buf = data->fuzz_buf; return size; } diff --git a/docs/Changelog.md b/docs/Changelog.md index 9f4a8653..3337feb9 100644 --- a/docs/Changelog.md +++ b/docs/Changelog.md @@ -30,6 +30,7 @@ - unicorn_mode: - updated and minor issues fixed - new custom module: autotoken, a grammar free fuzzer for text inputs + - fixed custom mutator C examples - better sanitizer default options support for all tools - more minor fixes and cross-platform support |