1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29#include <android/api-level.h> 30#include <elf.h> 31#include <errno.h> 32#include <stddef.h> 33#include <stdint.h> 34#include <stdio.h> 35#include <stdlib.h> 36#include <sys/auxv.h> 37#include <sys/mman.h> 38 39#include "libc_init_common.h" 40#include "pthread_internal.h" 41 42#include "private/bionic_globals.h" 43#include "private/bionic_page.h" 44#include "private/bionic_tls.h" 45#include "private/KernelArgumentBlock.h" 46 47extern "C" int __cxa_atexit(void (*)(void *), void *, void *); 48 49static void call_array(void(**list)()) { 50 // First element is -1, list is null-terminated 51 while (*++list) { 52 (*list)(); 53 } 54} 55 56static void apply_gnu_relro() { 57 ElfW(Phdr)* phdr_start = reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR)); 58 unsigned long int phdr_ct = getauxval(AT_PHNUM); 59 60 for (ElfW(Phdr)* phdr = phdr_start; phdr < (phdr_start + phdr_ct); phdr++) { 61 if (phdr->p_type != PT_GNU_RELRO) { 62 continue; 63 } 64 65 ElfW(Addr) seg_page_start = PAGE_START(phdr->p_vaddr); 66 ElfW(Addr) seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz); 67 68 // Check return value here? What do we do if we fail? 69 mprotect(reinterpret_cast<void*>(seg_page_start), seg_page_end - seg_page_start, PROT_READ); 70 } 71} 72 73// The program startup function __libc_init() defined here is 74// used for static executables only (i.e. those that don't depend 75// on shared libraries). It is called from arch-$ARCH/bionic/crtbegin_static.S 76// which is directly invoked by the kernel when the program is launched. 77// 78// The 'structors' parameter contains pointers to various initializer 79// arrays that must be run before the program's 'main' routine is launched. 80 81__noreturn void __libc_init(void* raw_args, 82 void (*onexit)(void) __unused, 83 int (*slingshot)(int, char**, char**), 84 structors_array_t const * const structors) { 85 KernelArgumentBlock args(raw_args); 86 __libc_init_main_thread(args); 87 88 // Initializing the globals requires TLS to be available for errno. 89 __init_thread_stack_guard(__get_thread()); 90 __libc_init_globals(args); 91 92 __libc_init_AT_SECURE(args); 93 __libc_init_common(args); 94 95 apply_gnu_relro(); 96 97 // Several Linux ABIs don't pass the onexit pointer, and the ones that 98 // do never use it. Therefore, we ignore it. 99 100 call_array(structors->preinit_array); 101 call_array(structors->init_array); 102 103 // The executable may have its own destructors listed in its .fini_array 104 // so we need to ensure that these are called when the program exits 105 // normally. 106 if (structors->fini_array != NULL) { 107 __cxa_atexit(__libc_fini,structors->fini_array,NULL); 108 } 109 110 exit(slingshot(args.argc, args.argv, args.envp)); 111} 112 113uint32_t bionic_get_application_target_sdk_version() { 114 return __ANDROID_API__; 115} 116