ptrace.c revision f0c5872637a63e28e3cd314cfc915c07f76df9c6
1501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown/* 2501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Copyright (C) 2011 The Android Open Source Project 3501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 4501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Licensed under the Apache License, Version 2.0 (the "License"); 5501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * you may not use this file except in compliance with the License. 6501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * You may obtain a copy of the License at 7501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 8501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * http://www.apache.org/licenses/LICENSE-2.0 9501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 10501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Unless required by applicable law or agreed to in writing, software 11501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * distributed under the License is distributed on an "AS IS" BASIS, 12501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * See the License for the specific language governing permissions and 14501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * limitations under the License. 15501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown */ 16501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 17501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#define LOG_TAG "Corkscrew" 18501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown//#define LOG_NDEBUG 0 19501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 20501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include "ptrace-arch.h" 21501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <corkscrew/ptrace.h> 22501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 23501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <errno.h> 24501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <sys/ptrace.h> 25501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <cutils/log.h> 26501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 27501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic const uint32_t ELF_MAGIC = 0x464C457f; // "ELF\0177" 28501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 29501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifndef PAGE_SIZE 30501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#define PAGE_SIZE 4096 31501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 32501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 33501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifndef PAGE_MASK 34501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#define PAGE_MASK (~(PAGE_SIZE - 1)) 35501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 36501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 37f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brownvoid init_memory(memory_t* memory, const map_info_t* map_info_list) { 38f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown memory->tid = -1; 39f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown memory->map_info_list = map_info_list; 40f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown} 41f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown 42f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brownvoid init_memory_ptrace(memory_t* memory, pid_t tid) { 43f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown memory->tid = tid; 44f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown memory->map_info_list = NULL; 45f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown} 46f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown 47f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brownbool try_get_word(const memory_t* memory, uintptr_t ptr, uint32_t* out_value) { 48f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown ALOGV("try_get_word: reading word at 0x%08x", ptr); 49501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (ptr & 3) { 5069f4cd7f5add7a7c7f5915e5292aab7eb2a42e9fSteve Block ALOGV("try_get_word: invalid pointer 0x%08x", ptr); 51f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown *out_value = 0xffffffffL; 52501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return false; 53501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 54f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown if (memory->tid < 0) { 55f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown if (!is_readable_map(memory->map_info_list, ptr)) { 56f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown ALOGV("try_get_word: pointer 0x%08x not in a readable map", ptr); 57f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown *out_value = 0xffffffffL; 58f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown return false; 59501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 60501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = *(uint32_t*)ptr; 61501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return true; 62501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } else { 63501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // ptrace() returns -1 and sets errno when the operation fails. 64501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // To disambiguate -1 from a valid result, we clear errno beforehand. 65501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown errno = 0; 66f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown *out_value = ptrace(PTRACE_PEEKTEXT, memory->tid, (void*)ptr, NULL); 67501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (*out_value == 0xffffffffL && errno) { 68f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown ALOGV("try_get_word: invalid pointer 0x%08x reading from tid %d, " 69f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown "ptrace() errno=%d", ptr, memory->tid, errno); 70501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return false; 71501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 72501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return true; 73501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 74501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 75501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 76f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brownbool try_get_word_ptrace(pid_t tid, uintptr_t ptr, uint32_t* out_value) { 77f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown memory_t memory; 78f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown init_memory_ptrace(&memory, tid); 79f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown return try_get_word(&memory, ptr, out_value); 80f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown} 81f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown 82501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) { 83f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown if (mi->is_executable && mi->is_readable) { 84501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown uint32_t elf_magic; 85f0c5872637a63e28e3cd314cfc915c07f76df9c6Jeff Brown if (try_get_word_ptrace(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) { 86501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t)); 87501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data) { 88501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown mi->data = data; 89501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (mi->name[0]) { 90501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown data->symbol_table = load_symbol_table(mi->name); 91501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 92501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifdef CORKSCREW_HAVE_ARCH 93501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown load_ptrace_map_info_data_arch(pid, mi, data); 94501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 95501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 96501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 97501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 98501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 99501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 100501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownptrace_context_t* load_ptrace_context(pid_t pid) { 101501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown ptrace_context_t* context = 102501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown (ptrace_context_t*)calloc(1, sizeof(ptrace_context_t)); 103501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (context) { 104501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown context->map_info_list = load_map_info_list(pid); 105501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) { 106501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown load_ptrace_map_info_data(pid, mi); 107501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 108501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 109501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return context; 110501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 111501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 112501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic void free_ptrace_map_info_data(map_info_t* mi) { 113501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown map_info_data_t* data = (map_info_data_t*)mi->data; 114501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data) { 115501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data->symbol_table) { 116501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_symbol_table(data->symbol_table); 117501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 118501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifdef CORKSCREW_HAVE_ARCH 119501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_ptrace_map_info_data_arch(mi, data); 120501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 121501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(data); 122501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown mi->data = NULL; 123501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 124501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 125501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 126501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownvoid free_ptrace_context(ptrace_context_t* context) { 127501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) { 128501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_ptrace_map_info_data(mi); 129501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 130501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_map_info_list(context->map_info_list); 131501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 132501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 133501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownvoid find_symbol_ptrace(const ptrace_context_t* context, 134501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) { 135501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const map_info_t* mi = find_map_info(context->map_info_list, addr); 136501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const symbol_t* symbol = NULL; 137501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (mi) { 138501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const map_info_data_t* data = (const map_info_data_t*)mi->data; 139501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data && data->symbol_table) { 140501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol = find_symbol(data->symbol_table, addr - mi->start); 141501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 142501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 143501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_map_info = mi; 144501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_symbol = symbol; 145501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 146