| /* |
| american fuzzy lop++ - LLVM instrumentation bootstrap |
| --------------------------------------------------- |
| |
| Written by Laszlo Szekeres <lszekeres@google.com> and |
| Michal Zalewski |
| |
| LLVM integration design comes from Laszlo Szekeres. |
| |
| Copyright 2015, 2016 Google Inc. All rights reserved. |
| Copyright 2019-2020 AFLplusplus Project. All rights reserved. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at: |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| This code is the rewrite of afl-as.h's main_payload. |
| |
| */ |
| |
| #ifdef __ANDROID__ |
| #include "android-ashmem.h" |
| #endif |
| #include "config.h" |
| #include "types.h" |
| #include "cmplog.h" |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <signal.h> |
| #include <unistd.h> |
| #include <string.h> |
| #include <assert.h> |
| #include <stdint.h> |
| #include <errno.h> |
| |
| #include <sys/mman.h> |
| #include <sys/shm.h> |
| #include <sys/wait.h> |
| #include <sys/types.h> |
| |
| /* This is a somewhat ugly hack for the experimental 'trace-pc-guard' mode. |
| Basically, we need to make sure that the forkserver is initialized after |
| the LLVM-generated runtime initialization pass, not before. */ |
| |
| #ifdef USE_TRACE_PC |
| #define CONST_PRIO 5 |
| #else |
| #define CONST_PRIO 0 |
| #endif /* ^USE_TRACE_PC */ |
| |
| #include <sys/mman.h> |
| #include <fcntl.h> |
| |
| /* Globals needed by the injected instrumentation. The __afl_area_initial region |
| is used for instrumentation output before __afl_map_shm() has a chance to |
| run. It will end up as .comm, so it shouldn't be too wasteful. */ |
| |
| u8 __afl_area_initial[MAP_SIZE]; |
| u8* __afl_area_ptr = __afl_area_initial; |
| |
| #ifdef __ANDROID__ |
| u32 __afl_prev_loc; |
| u32 __afl_final_loc; |
| #else |
| __thread u32 __afl_prev_loc; |
| __thread u32 __afl_final_loc; |
| #endif |
| |
| struct cmp_map* __afl_cmp_map; |
| __thread u32 __afl_cmp_counter; |
| |
| /* Running in persistent mode? */ |
| |
| static u8 is_persistent; |
| |
| /* SHM setup. */ |
| |
| static void __afl_map_shm(void) { |
| |
| u8* id_str = getenv(SHM_ENV_VAR); |
| |
| /* If we're running under AFL, attach to the appropriate region, replacing the |
| early-stage __afl_area_initial region that is needed to allow some really |
| hacky .init code to work correctly in projects such as OpenSSL. */ |
| |
| if (id_str) { |
| |
| #ifdef USEMMAP |
| const char* shm_file_path = id_str; |
| int shm_fd = -1; |
| unsigned char* shm_base = NULL; |
| |
| /* create the shared memory segment as if it was a file */ |
| shm_fd = shm_open(shm_file_path, O_RDWR, 0600); |
| if (shm_fd == -1) { |
| |
| printf("shm_open() failed\n"); |
| exit(1); |
| |
| } |
| |
| /* map the shared memory segment to the address space of the process */ |
| shm_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0); |
| if (shm_base == MAP_FAILED) { |
| |
| close(shm_fd); |
| shm_fd = -1; |
| |
| printf("mmap() failed\n"); |
| exit(2); |
| |
| } |
| |
| __afl_area_ptr = shm_base; |
| #else |
| u32 shm_id = atoi(id_str); |
| |
| __afl_area_ptr = shmat(shm_id, NULL, 0); |
| #endif |
| |
| /* Whooooops. */ |
| |
| if (__afl_area_ptr == (void*)-1) _exit(1); |
| |
| /* Write something into the bitmap so that even with low AFL_INST_RATIO, |
| our parent doesn't give up on us. */ |
| |
| __afl_area_ptr[0] = 1; |
| |
| } |
| |
| id_str = getenv(CMPLOG_SHM_ENV_VAR); |
| |
| if (id_str) { |
| |
| #ifdef USEMMAP |
| const char* shm_file_path = id_str; |
| int shm_fd = -1; |
| unsigned char* shm_base = NULL; |
| |
| /* create the shared memory segment as if it was a file */ |
| shm_fd = shm_open(shm_file_path, O_RDWR, 0600); |
| if (shm_fd == -1) { |
| |
| printf("shm_open() failed\n"); |
| exit(1); |
| |
| } |
| |
| /* map the shared memory segment to the address space of the process */ |
| shm_base = mmap(0, sizeof(struct cmp_map), PROT_READ | PROT_WRITE, |
| MAP_SHARED, shm_fd, 0); |
| if (shm_base == MAP_FAILED) { |
| |
| close(shm_fd); |
| shm_fd = -1; |
| |
| printf("mmap() failed\n"); |
| exit(2); |
| |
| } |
| |
| __afl_cmp_map = shm_base; |
| #else |
| u32 shm_id = atoi(id_str); |
| |
| __afl_cmp_map = shmat(shm_id, NULL, 0); |
| #endif |
| |
| if (__afl_cmp_map == (void*)-1) _exit(1); |
| |
| } |
| |
| } |
| |
| /* Fork server logic. */ |
| |
| static void __afl_start_forkserver(void) { |
| |
| static u8 tmp[4]; |
| s32 child_pid; |
| |
| u8 child_stopped = 0; |
| |
| void (*old_sigchld_handler)(int) = 0; // = signal(SIGCHLD, SIG_DFL); |
| |
| /* Phone home and tell the parent that we're OK. If parent isn't there, |
| assume we're not running in forkserver mode and just execute program. */ |
| |
| if (write(FORKSRV_FD + 1, tmp, 4) != 4) return; |
| |
| while (1) { |
| |
| u32 was_killed; |
| int status; |
| |
| /* Wait for parent by reading from the pipe. Abort if read fails. */ |
| |
| if (read(FORKSRV_FD, &was_killed, 4) != 4) _exit(1); |
| |
| /* If we stopped the child in persistent mode, but there was a race |
| condition and afl-fuzz already issued SIGKILL, write off the old |
| process. */ |
| |
| if (child_stopped && was_killed) { |
| |
| child_stopped = 0; |
| if (waitpid(child_pid, &status, 0) < 0) _exit(1); |
| |
| } |
| |
| if (!child_stopped) { |
| |
| /* Once woken up, create a clone of our process. */ |
| |
| child_pid = fork(); |
| if (child_pid < 0) _exit(1); |
| |
| /* In child process: close fds, resume execution. */ |
| |
| if (!child_pid) { |
| |
| signal(SIGCHLD, old_sigchld_handler); |
| |
| close(FORKSRV_FD); |
| close(FORKSRV_FD + 1); |
| return; |
| |
| } |
| |
| } else { |
| |
| /* Special handling for persistent mode: if the child is alive but |
| currently stopped, simply restart it with SIGCONT. */ |
| |
| kill(child_pid, SIGCONT); |
| child_stopped = 0; |
| |
| } |
| |
| /* In parent process: write PID to pipe, then wait for child. */ |
| |
| if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) _exit(1); |
| |
| if (waitpid(child_pid, &status, is_persistent ? WUNTRACED : 0) < 0) |
| _exit(1); |
| |
| /* In persistent mode, the child stops itself with SIGSTOP to indicate |
| a successful run. In this case, we want to wake it up without forking |
| again. */ |
| |
| if (WIFSTOPPED(status)) child_stopped = 1; |
| |
| /* Relay wait status to pipe, then loop back. */ |
| |
| if (write(FORKSRV_FD + 1, &status, 4) != 4) _exit(1); |
| |
| } |
| |
| } |
| |
| /* A simplified persistent mode handler, used as explained in |
| * llvm_mode/README.md. */ |
| |
| int __afl_persistent_loop(unsigned int max_cnt) { |
| |
| static u8 first_pass = 1; |
| static u32 cycle_cnt; |
| |
| if (first_pass) { |
| |
| /* Make sure that every iteration of __AFL_LOOP() starts with a clean slate. |
| On subsequent calls, the parent will take care of that, but on the first |
| iteration, it's our job to erase any trace of whatever happened |
| before the loop. */ |
| |
| if (is_persistent) { |
| |
| memset(__afl_area_ptr, 0, MAP_SIZE); |
| __afl_area_ptr[0] = 1; |
| __afl_prev_loc = 0; |
| |
| } |
| |
| cycle_cnt = max_cnt; |
| first_pass = 0; |
| return 1; |
| |
| } |
| |
| if (is_persistent) { |
| |
| if (--cycle_cnt) { |
| |
| raise(SIGSTOP); |
| |
| __afl_area_ptr[0] = 1; |
| __afl_prev_loc = 0; |
| |
| return 1; |
| |
| } else { |
| |
| /* When exiting __AFL_LOOP(), make sure that the subsequent code that |
| follows the loop is not traced. We do that by pivoting back to the |
| dummy output region. */ |
| |
| __afl_area_ptr = __afl_area_initial; |
| |
| } |
| |
| } |
| |
| return 0; |
| |
| } |
| |
| /* This one can be called from user code when deferred forkserver mode |
| is enabled. */ |
| |
| void __afl_manual_init(void) { |
| |
| static u8 init_done; |
| |
| if (!init_done) { |
| |
| __afl_map_shm(); |
| __afl_start_forkserver(); |
| init_done = 1; |
| |
| } |
| |
| } |
| |
| /* Proper initialization routine. */ |
| |
| __attribute__((constructor(CONST_PRIO))) void __afl_auto_init(void) { |
| |
| is_persistent = !!getenv(PERSIST_ENV_VAR); |
| |
| if (getenv(DEFER_ENV_VAR)) return; |
| |
| __afl_manual_init(); |
| |
| } |
| |
| /* The following stuff deals with supporting -fsanitize-coverage=trace-pc-guard. |
| It remains non-operational in the traditional, plugin-backed LLVM mode. |
| For more info about 'trace-pc-guard', see llvm_mode/README.md. |
| |
| The first function (__sanitizer_cov_trace_pc_guard) is called back on every |
| edge (as opposed to every basic block). */ |
| |
| void __sanitizer_cov_trace_pc_guard(uint32_t* guard) { |
| |
| __afl_area_ptr[*guard]++; |
| |
| } |
| |
| /* Init callback. Populates instrumentation IDs. Note that we're using |
| ID of 0 as a special value to indicate non-instrumented bits. That may |
| still touch the bitmap, but in a fairly harmless way. */ |
| |
| void __sanitizer_cov_trace_pc_guard_init(uint32_t* start, uint32_t* stop) { |
| |
| u32 inst_ratio = 100; |
| u8* x; |
| |
| if (start == stop || *start) return; |
| |
| x = getenv("AFL_INST_RATIO"); |
| if (x) inst_ratio = atoi(x); |
| |
| if (!inst_ratio || inst_ratio > 100) { |
| |
| fprintf(stderr, "[-] ERROR: Invalid AFL_INST_RATIO (must be 1-100).\n"); |
| abort(); |
| |
| } |
| |
| /* Make sure that the first element in the range is always set - we use that |
| to avoid duplicate calls (which can happen as an artifact of the underlying |
| implementation in LLVM). */ |
| |
| *(start++) = R(MAP_SIZE - 1) + 1; |
| |
| while (start < stop) { |
| |
| if (R(100) < inst_ratio) |
| *start = R(MAP_SIZE - 1) + 1; |
| else |
| *start = 0; |
| |
| start++; |
| |
| } |
| |
| } |
| |
| ///// CmpLog instrumentation |
| |
| void __cmplog_ins_hook1(uint8_t Arg1, uint8_t Arg2) { |
| |
| return; |
| |
| } |
| |
| void __cmplog_ins_hook2(uint16_t Arg1, uint16_t Arg2) { |
| |
| if (!__afl_cmp_map) return; |
| |
| uintptr_t k = (uintptr_t)__builtin_return_address(0); |
| k = (k >> 4) ^ (k << 8); |
| k &= CMP_MAP_W - 1; |
| |
| __afl_cmp_map->headers[k].type = CMP_TYPE_INS; |
| |
| u32 hits = __afl_cmp_map->headers[k].hits; |
| __afl_cmp_map->headers[k].hits = hits + 1; |
| // if (!__afl_cmp_map->headers[k].cnt) |
| // __afl_cmp_map->headers[k].cnt = __afl_cmp_counter++; |
| |
| __afl_cmp_map->headers[k].shape = 1; |
| //__afl_cmp_map->headers[k].type = CMP_TYPE_INS; |
| |
| hits &= CMP_MAP_H - 1; |
| __afl_cmp_map->log[k][hits].v0 = Arg1; |
| __afl_cmp_map->log[k][hits].v1 = Arg2; |
| |
| } |
| |
| void __cmplog_ins_hook4(uint32_t Arg1, uint32_t Arg2) { |
| |
| if (!__afl_cmp_map) return; |
| |
| uintptr_t k = (uintptr_t)__builtin_return_address(0); |
| k = (k >> 4) ^ (k << 8); |
| k &= CMP_MAP_W - 1; |
| |
| __afl_cmp_map->headers[k].type = CMP_TYPE_INS; |
| |
| u32 hits = __afl_cmp_map->headers[k].hits; |
| __afl_cmp_map->headers[k].hits = hits + 1; |
| |
| __afl_cmp_map->headers[k].shape = 3; |
| |
| hits &= CMP_MAP_H - 1; |
| __afl_cmp_map->log[k][hits].v0 = Arg1; |
| __afl_cmp_map->log[k][hits].v1 = Arg2; |
| |
| } |
| |
| void __cmplog_ins_hook8(uint64_t Arg1, uint64_t Arg2) { |
| |
| if (!__afl_cmp_map) return; |
| |
| uintptr_t k = (uintptr_t)__builtin_return_address(0); |
| k = (k >> 4) ^ (k << 8); |
| k &= CMP_MAP_W - 1; |
| |
| __afl_cmp_map->headers[k].type = CMP_TYPE_INS; |
| |
| u32 hits = __afl_cmp_map->headers[k].hits; |
| __afl_cmp_map->headers[k].hits = hits + 1; |
| |
| __afl_cmp_map->headers[k].shape = 7; |
| |
| hits &= CMP_MAP_H - 1; |
| __afl_cmp_map->log[k][hits].v0 = Arg1; |
| __afl_cmp_map->log[k][hits].v1 = Arg2; |
| |
| } |
| |
| #if defined(__APPLE__) |
| #pragma weak __sanitizer_cov_trace_const_cmp1 = __cmplog_ins_hook1 |
| #pragma weak __sanitizer_cov_trace_const_cmp2 = __cmplog_ins_hook2 |
| #pragma weak __sanitizer_cov_trace_const_cmp4 = __cmplog_ins_hook4 |
| #pragma weak __sanitizer_cov_trace_const_cmp8 = __cmplog_ins_hook8 |
| |
| #pragma weak __sanitizer_cov_trace_cmp1 = __cmplog_ins_hook1 |
| #pragma weak __sanitizer_cov_trace_cmp2 = __cmplog_ins_hook2 |
| #pragma weak __sanitizer_cov_trace_cmp4 = __cmplog_ins_hook4 |
| #pragma weak __sanitizer_cov_trace_cmp8 = __cmplog_ins_hook8 |
| #else |
| void __sanitizer_cov_trace_const_cmp1(uint8_t Arg1, uint8_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook1"))); |
| void __sanitizer_cov_trace_const_cmp2(uint16_t Arg1, uint16_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook2"))); |
| void __sanitizer_cov_trace_const_cmp4(uint32_t Arg1, uint32_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook4"))); |
| void __sanitizer_cov_trace_const_cmp8(uint64_t Arg1, uint64_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook8"))); |
| |
| void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook1"))); |
| void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook2"))); |
| void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook4"))); |
| void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) |
| __attribute__((alias("__cmplog_ins_hook8"))); |
| #endif /* defined(__APPLE__) */ |
| |
| void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t* Cases) { |
| |
| for (uint64_t i = 0; i < Cases[0]; i++) { |
| |
| uintptr_t k = (uintptr_t)__builtin_return_address(0) + i; |
| k = (k >> 4) ^ (k << 8); |
| k &= CMP_MAP_W - 1; |
| |
| __afl_cmp_map->headers[k].type = CMP_TYPE_INS; |
| |
| u32 hits = __afl_cmp_map->headers[k].hits; |
| __afl_cmp_map->headers[k].hits = hits + 1; |
| |
| __afl_cmp_map->headers[k].shape = 7; |
| |
| hits &= CMP_MAP_H - 1; |
| __afl_cmp_map->log[k][hits].v0 = Val; |
| __afl_cmp_map->log[k][hits].v1 = Cases[i + 2]; |
| |
| } |
| |
| } |
| |
| // POSIX shenanigan to see if an area is mapped. |
| // If it is mapped as X-only, we have a problem, so maybe we should add a check |
| // to avoid to call it on .text addresses |
| static int area_is_mapped(void* ptr, size_t len) { |
| |
| char* p = ptr; |
| char* page = (char*)((uintptr_t)p & ~(sysconf(_SC_PAGE_SIZE) - 1)); |
| |
| int r = msync(page, (p - page) + len, MS_ASYNC); |
| if (r < 0) return errno != ENOMEM; |
| return 1; |
| |
| } |
| |
| void __cmplog_rtn_hook(void* ptr1, void* ptr2) { |
| |
| if (!__afl_cmp_map) return; |
| |
| if (!area_is_mapped(ptr1, 32) || !area_is_mapped(ptr2, 32)) return; |
| |
| uintptr_t k = (uintptr_t)__builtin_return_address(0); |
| k = (k >> 4) ^ (k << 8); |
| k &= CMP_MAP_W - 1; |
| |
| __afl_cmp_map->headers[k].type = CMP_TYPE_RTN; |
| |
| u32 hits = __afl_cmp_map->headers[k].hits; |
| __afl_cmp_map->headers[k].hits = hits + 1; |
| |
| __afl_cmp_map->headers[k].shape = 31; |
| |
| hits &= CMP_MAP_RTN_H - 1; |
| __builtin_memcpy(((struct cmpfn_operands*)__afl_cmp_map->log[k])[hits].v0, |
| ptr1, 32); |
| __builtin_memcpy(((struct cmpfn_operands*)__afl_cmp_map->log[k])[hits].v1, |
| ptr2, 32); |
| |
| } |
| |