diff options
Diffstat (limited to 'instrumentation/afl-compiler-rt.o.c')
| -rw-r--r-- | instrumentation/afl-compiler-rt.o.c | 279 |
1 files changed, 256 insertions, 23 deletions
diff --git a/instrumentation/afl-compiler-rt.o.c b/instrumentation/afl-compiler-rt.o.c index 39a762b6..8e55d6a0 100644 --- a/instrumentation/afl-compiler-rt.o.c +++ b/instrumentation/afl-compiler-rt.o.c @@ -22,6 +22,10 @@ #define __USE_GNU #endif #include <dlfcn.h> + +__attribute__((weak)) void __sanitizer_symbolize_pc(void *, const char *fmt, + char *out_buf, + size_t out_buf_size); #endif #ifdef __ANDROID__ @@ -124,8 +128,8 @@ struct afl_module_info_t { uintptr_t base_address; // PC Guard start/stop - u32 start; - u32 stop; + u32 *start; + u32 *stop; // PC Table begin/end const uintptr_t *pcs_beg; @@ -147,6 +151,18 @@ afl_module_info_t *__afl_module_info = NULL; u32 __afl_pcmap_size = 0; uintptr_t *__afl_pcmap_ptr = NULL; + +typedef struct { + + uintptr_t start; + u32 len; + +} FilterPCEntry; + +u32 __afl_filter_pcs_size = 0; +FilterPCEntry *__afl_filter_pcs = NULL; +u8 *__afl_filter_pcs_module = NULL; + #endif // __AFL_CODE_COVERAGE /* 1 if we are running in afl, and the forkserver was started, else 0 */ @@ -1587,15 +1603,116 @@ void __sanitizer_cov_trace_pc_guard(uint32_t *guard) { } #ifdef __AFL_CODE_COVERAGE -void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, - const uintptr_t *pcs_end) { +void afl_read_pc_filter_file(const char *filter_file) { - if (__afl_debug) { + FILE *file; + char ch; + + file = fopen(filter_file, "r"); + if (file == NULL) { + + perror("Error opening file"); + return; + + } + + // Check how many PCs we expect to read + while ((ch = fgetc(file)) != EOF) { + + if (ch == '\n') { __afl_filter_pcs_size++; } + + } + + // Rewind to actually read the PCs + fseek(file, 0, SEEK_SET); + + __afl_filter_pcs = malloc(__afl_filter_pcs_size * sizeof(FilterPCEntry)); + if (!__afl_filter_pcs) { + + perror("Error allocating PC array"); + return; + + } + + for (size_t i = 0; i < __afl_filter_pcs_size; i++) { + + fscanf(file, "%lx", &(__afl_filter_pcs[i].start)); + ch = fgetc(file); // Read tab + fscanf(file, "%u", &(__afl_filter_pcs[i].len)); + ch = fgetc(file); // Read tab + + if (!__afl_filter_pcs_module) { + + // Read the module name and store it. + // TODO: We only support one module here right now although + // there is technically no reason to support multiple modules + // in one go. + size_t max_module_len = 255; + size_t i = 0; + __afl_filter_pcs_module = malloc(max_module_len); + while (i < max_module_len - 1 && + (__afl_filter_pcs_module[i] = fgetc(file)) != '\t') { + + ++i; + + } - fprintf(stderr, "DEBUG: __sanitizer_cov_pcs_init called\n"); + __afl_filter_pcs_module[i] = '\0'; + fprintf(stderr, "DEBUGXXX: Read module name %s\n", + __afl_filter_pcs_module); + + } + + while ((ch = fgetc(file)) != '\n' && ch != EOF) + ; + + } + + fclose(file); + +} + +u32 locate_in_pcs(uintptr_t needle, u32 *index) { + + size_t lower_bound = 0; + size_t upper_bound = __afl_filter_pcs_size - 1; + + while (lower_bound < __afl_filter_pcs_size && lower_bound <= upper_bound) { + + size_t current_index = lower_bound + (upper_bound - lower_bound) / 2; + + if (__afl_filter_pcs[current_index].start <= needle) { + + if (__afl_filter_pcs[current_index].start + + __afl_filter_pcs[current_index].len > + needle) { + + // Hit + *index = current_index; + return 1; + + } else { + + lower_bound = current_index + 1; + + } + + } else { + + if (!current_index) { break; } + upper_bound = current_index - 1; + + } } + return 0; + +} + +void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, + const uintptr_t *pcs_end) { + // If for whatever reason, we cannot get dlinfo here, then pc_guard_init also // couldn't get it and we'd end up attributing to the wrong module. Dl_info dlinfo; @@ -1608,6 +1725,16 @@ void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, } + if (__afl_debug) { + + fprintf( + stderr, + "DEBUG: (%u) __sanitizer_cov_pcs_init called for module %s with %ld " + "PCs\n", + getpid(), dlinfo.dli_fname, pcs_end - pcs_beg); + + } + afl_module_info_t *last_module_info = __afl_module_info; while (last_module_info && last_module_info->next) { @@ -1623,34 +1750,78 @@ void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, } + if (strcmp(dlinfo.dli_fname, last_module_info->name)) { + + // This can happen with modules being loaded after the forkserver + // where we decide to not track the module. In that case we must + // not track it here either. + fprintf( + stderr, + "WARNING: __sanitizer_cov_pcs_init module info mismatch: %s vs %s\n", + dlinfo.dli_fname, last_module_info->name); + return; + + } + last_module_info->pcs_beg = pcs_beg; last_module_info->pcs_end = pcs_end; + // This is a direct filter based on symbolizing inside the runtime. + // It should only be used with smaller binaries to avoid long startup + // times. Currently, this only supports a single token to scan for. + const char *pc_filter = getenv("AFL_PC_FILTER"); + + // This is a much faster PC filter based on pre-symbolized input data + // that is sorted for fast lookup through binary search. This method + // of filtering is suitable even for very large binaries. + const char *pc_filter_file = getenv("AFL_PC_FILTER_FILE"); + if (pc_filter_file && !__afl_filter_pcs) { + + afl_read_pc_filter_file(pc_filter_file); + + } + // Now update the pcmap. If this is the last module coming in, after all // pre-loaded code, then this will also map all of our delayed previous // modules. - - if (!__afl_pcmap_ptr) { return; } - + // for (afl_module_info_t *mod_info = __afl_module_info; mod_info; mod_info = mod_info->next) { if (mod_info->mapped) { continue; } + if (!mod_info->start) { + + fprintf(stderr, + "ERROR: __sanitizer_cov_pcs_init called with mod_info->start == " + "NULL (%s)\n", + mod_info->name); + abort(); + + } + PCTableEntry *start = (PCTableEntry *)(mod_info->pcs_beg); PCTableEntry *end = (PCTableEntry *)(mod_info->pcs_end); + if (!*mod_info->stop) { continue; } + u32 in_module_index = 0; while (start < end) { - if (mod_info->start + in_module_index >= __afl_map_size) { + if (*mod_info->start + in_module_index >= __afl_map_size) { - fprintf(stderr, "ERROR: __sanitizer_cov_pcs_init out of bounds?!\n"); + fprintf(stderr, + "ERROR: __sanitizer_cov_pcs_init out of bounds?! Start: %u " + "Stop: %u Map Size: %u (%s)\n", + *mod_info->start, *mod_info->stop, __afl_map_size, + mod_info->name); abort(); } + u32 orig_start_index = *mod_info->start; + uintptr_t PC = start->PC; // This is what `GetPreviousInstructionPc` in sanitizer runtime does @@ -1660,7 +1831,58 @@ void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, // Calculate relative offset in module PC = PC - mod_info->base_address; - __afl_pcmap_ptr[mod_info->start + in_module_index] = PC; + if (__afl_pcmap_ptr) { + + __afl_pcmap_ptr[orig_start_index + in_module_index] = PC; + + } + + if (pc_filter) { + + char PcDescr[1024]; + // This function is a part of the sanitizer run-time. + // To use it, link with AddressSanitizer or other sanitizer. + __sanitizer_symbolize_pc((void *)start->PC, "%p %F %L", PcDescr, + sizeof(PcDescr)); + + if (strstr(PcDescr, pc_filter)) { + + if (__afl_debug) + fprintf( + stderr, + "DEBUG: Selective instrumentation match: %s (PC %p Index %u)\n", + PcDescr, (void *)start->PC, + *(mod_info->start + in_module_index)); + // No change to guard needed + + } else { + + // Null out the guard to disable this edge + *(mod_info->start + in_module_index) = 0; + + } + + } + + if (__afl_filter_pcs && strstr(mod_info->name, __afl_filter_pcs_module)) { + + u32 result_index; + if (locate_in_pcs(PC, &result_index)) { + + if (__afl_debug) + fprintf(stderr, + "DEBUG: Selective instrumentation match: (PC %lx File " + "Index %u PC Index %u)\n", + PC, result_index, in_module_index); + + } else { + + // Null out the guard to disable this edge + *(mod_info->start + in_module_index) = 0; + + } + + } start++; in_module_index++; @@ -1671,8 +1893,10 @@ void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg, if (__afl_debug) { - fprintf(stderr, "DEBUG: __sanitizer_cov_pcs_init initialized %u PCs\n", - in_module_index); + fprintf(stderr, + "DEBUG: __sanitizer_cov_pcs_init successfully mapped %s with %u " + "PCs\n", + mod_info->name, in_module_index); } @@ -1706,9 +1930,9 @@ void __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop) { fprintf( stderr, "DEBUG: Running __sanitizer_cov_trace_pc_guard_init: %p-%p (%lu edges) " - "after_fs=%u\n", + "after_fs=%u *start=%u\n", start, stop, (unsigned long)(stop - start), - __afl_already_initialized_forkserver); + __afl_already_initialized_forkserver, *start); } @@ -1740,8 +1964,8 @@ void __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop) { mod_info->id = last_module_info ? last_module_info->id + 1 : 0; mod_info->name = strdup(dlinfo.dli_fname); mod_info->base_address = (uintptr_t)dlinfo.dli_fbase; - mod_info->start = 0; - mod_info->stop = 0; + mod_info->start = NULL; + mod_info->stop = NULL; mod_info->pcs_beg = NULL; mod_info->pcs_end = NULL; mod_info->mapped = 0; @@ -1757,8 +1981,12 @@ void __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop) { } - fprintf(stderr, "[pcmap] Module: %s Base Address: %p\n", dlinfo.dli_fname, - dlinfo.dli_fbase); + if (__afl_debug) { + + fprintf(stderr, "[pcmap] Module: %s Base Address: %p\n", + dlinfo.dli_fname, dlinfo.dli_fbase); + + } } @@ -1861,12 +2089,17 @@ void __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop) { #ifdef __AFL_CODE_COVERAGE if (mod_info) { - mod_info->start = *orig_start; - mod_info->stop = *(stop - 1); + if (!mod_info->start) { + + mod_info->start = orig_start; + mod_info->stop = stop - 1; + + } + if (__afl_debug) { fprintf(stderr, "DEBUG: [pcmap] Start Index: %u Stop Index: %u\n", - mod_info->start, mod_info->stop); + *(mod_info->start), *(mod_info->stop)); } |