ptrace.c revision 501edd29b823ce1301d2effdd3a9e4b6e2b20b76
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 37501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownbool try_get_word(pid_t tid, uintptr_t ptr, uint32_t* out_value) { 38501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (ptr & 3) { 39501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown LOGV("try_get_word: invalid pointer 0x%08x", ptr); 40501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = 0; 41501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return false; 42501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 43501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (tid < 0) { 44501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#if 0 /*unreliable, unclear whether this is safe from a signal handler context*/ 45501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Determine whether the pointer is likely to be valid before dereferencing it. 46501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown unsigned char vec[1]; 47501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown while (mincore((void*)(ptr & PAGE_MASK), sizeof(uint32_t), vec)) { 48501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (errno != EAGAIN && errno != EINTR) { 49501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown LOGV("try_get_word: invalid pointer 0x%08x, mincore() errno=%d", ptr, errno); 50501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = 0; 51501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return false; 52501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 53501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 54501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 55501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = *(uint32_t*)ptr; 56501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return true; 57501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } else { 58501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // ptrace() returns -1 and sets errno when the operation fails. 59501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // To disambiguate -1 from a valid result, we clear errno beforehand. 60501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown errno = 0; 61501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = ptrace(PTRACE_PEEKTEXT, tid, (void*)ptr, NULL); 62501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (*out_value == 0xffffffffL && errno) { 63501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown LOGV("try_get_word: invalid pointer 0x%08x, ptrace() errno=%d", ptr, errno); 64501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_value = 0; 65501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return false; 66501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 67501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return true; 68501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 69501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 70501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 71501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) { 72501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (mi->is_executable) { 73501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown uint32_t elf_magic; 74501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (try_get_word(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) { 75501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t)); 76501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data) { 77501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown mi->data = data; 78501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (mi->name[0]) { 79501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown data->symbol_table = load_symbol_table(mi->name); 80501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 81501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifdef CORKSCREW_HAVE_ARCH 82501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown load_ptrace_map_info_data_arch(pid, mi, data); 83501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 84501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 85501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 86501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 87501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 88501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 89501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownptrace_context_t* load_ptrace_context(pid_t pid) { 90501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown ptrace_context_t* context = 91501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown (ptrace_context_t*)calloc(1, sizeof(ptrace_context_t)); 92501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (context) { 93501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown context->map_info_list = load_map_info_list(pid); 94501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) { 95501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown load_ptrace_map_info_data(pid, mi); 96501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 97501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 98501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return context; 99501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 100501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 101501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic void free_ptrace_map_info_data(map_info_t* mi) { 102501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown map_info_data_t* data = (map_info_data_t*)mi->data; 103501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data) { 104501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data->symbol_table) { 105501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_symbol_table(data->symbol_table); 106501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 107501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#ifdef CORKSCREW_HAVE_ARCH 108501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_ptrace_map_info_data_arch(mi, data); 109501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#endif 110501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(data); 111501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown mi->data = NULL; 112501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 113501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 114501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 115501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownvoid free_ptrace_context(ptrace_context_t* context) { 116501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) { 117501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_ptrace_map_info_data(mi); 118501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 119501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free_map_info_list(context->map_info_list); 120501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 121501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 122501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownvoid find_symbol_ptrace(const ptrace_context_t* context, 123501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) { 124501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const map_info_t* mi = find_map_info(context->map_info_list, addr); 125501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const symbol_t* symbol = NULL; 126501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (mi) { 127501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const map_info_data_t* data = (const map_info_data_t*)mi->data; 128501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (data && data->symbol_table) { 129501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol = find_symbol(data->symbol_table, addr - mi->start); 130501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 131501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 132501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_map_info = mi; 133501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown *out_symbol = symbol; 134501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 135