b6453c52ac
Before, dynamic executables would initialize the global stack protector twice, once for the linker, and once for the executable. This worked because the result was the same for both initializations, because it used getauxval(AT_RANDOM), which won't be the case once arc4random gets used for it. Bug: http://b/29622562 Change-Id: I7718b1ba8ee8fac7127ab2360cb1088e510fef5c Test: ran the stack protector tests on angler (32/64bit, static/dynamic)
121 lines
4.7 KiB
C++
121 lines
4.7 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* libc_init_dynamic.c
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*
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* This source files provides two important functions for dynamic
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* executables:
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*
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* - a C runtime initializer (__libc_preinit), which is called by
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* the dynamic linker when libc.so is loaded. This happens before
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* any other initializer (e.g. static C++ constructors in other
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* shared libraries the program depends on).
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*
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* - a program launch function (__libc_init), which is called after
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* all dynamic linking has been performed. Technically, it is called
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* from arch-$ARCH/bionic/crtbegin_dynamic.S which is itself called
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* by the dynamic linker after all libraries have been loaded and
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* initialized.
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*/
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <elf.h>
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#include "libc_init_common.h"
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#include "private/bionic_globals.h"
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#include "private/bionic_ssp.h"
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#include "private/bionic_tls.h"
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#include "private/KernelArgumentBlock.h"
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extern "C" {
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extern void netdClientInit(void);
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extern int __cxa_atexit(void (*)(void *), void *, void *);
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};
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// We flag the __libc_preinit function as a constructor to ensure
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// that its address is listed in libc.so's .init_array section.
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// This ensures that the function is called by the dynamic linker
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// as soon as the shared library is loaded.
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__attribute__((constructor)) static void __libc_preinit() {
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// Read the kernel argument block pointer from TLS.
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void** tls = __get_tls();
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KernelArgumentBlock** args_slot = &reinterpret_cast<KernelArgumentBlock**>(tls)[TLS_SLOT_BIONIC_PREINIT];
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KernelArgumentBlock* args = *args_slot;
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// Clear the slot so no other initializer sees its value.
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// __libc_init_common() will change the TLS area so the old one won't be accessible anyway.
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*args_slot = NULL;
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// The linker has initialized its copy of the global stack_chk_guard, and filled in the main
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// thread's TLS slot with that value. Initialize the local global stack guard with its value.
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__stack_chk_guard = reinterpret_cast<uintptr_t>(tls[TLS_SLOT_STACK_GUARD]);
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__libc_init_globals(*args);
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__libc_init_common(*args);
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// Hooks for various libraries to let them know that we're starting up.
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__libc_globals.mutate(__libc_init_malloc);
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netdClientInit();
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}
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// This function is called from the executable's _start entry point
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// (see arch-$ARCH/bionic/crtbegin_dynamic.S), which is itself
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// called by the dynamic linker after it has loaded all shared
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// libraries the executable depends on.
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//
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// Note that the dynamic linker has also run all constructors in the
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// executable at this point.
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__noreturn void __libc_init(void* raw_args,
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void (*onexit)(void) __unused,
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors) {
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KernelArgumentBlock args(raw_args);
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// Several Linux ABIs don't pass the onexit pointer, and the ones that
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// do never use it. Therefore, we ignore it.
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// The executable may have its own destructors listed in its .fini_array
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// so we need to ensure that these are called when the program exits
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// normally.
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if (structors->fini_array) {
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__cxa_atexit(__libc_fini,structors->fini_array,NULL);
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}
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exit(slingshot(args.argc, args.argv, args.envp));
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}
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extern "C" uint32_t android_get_application_target_sdk_version();
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uint32_t bionic_get_application_target_sdk_version() {
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return android_get_application_target_sdk_version();
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}
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