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Merge "Revert "Attempt to use arc4random where getauxval(AT_RANDOM) is used.""

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Josh Gao 2016-09-02 05:49:21 +00:00 committed by Gerrit Code Review
commit 2f159f0bca
5 changed files with 7 additions and 110 deletions
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1
libc/Android.bp
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@ -1211,7 +1211,6 @@ cc_library_static {
"bionic/arpa_inet.cpp",
"bionic/assert.cpp",
"bionic/atof.cpp",
"bionic/bionic_arc4random.cpp",
"bionic/bionic_netlink.cpp",
"bionic/bionic_systrace.cpp",
"bionic/bionic_time_conversions.cpp",

5
libc/bionic/__libc_init_main_thread.cpp
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@ -29,7 +29,6 @@
#include "libc_init_common.h"
#include "private/KernelArgumentBlock.h"
#include "private/bionic_arc4random.h"
#include "private/bionic_auxv.h"
#include "private/bionic_globals.h"
#include "private/bionic_ssp.h"
@ -42,7 +41,9 @@ extern "C" int __set_tid_address(int* tid_address);
uintptr_t __stack_chk_guard = 0;
void __libc_init_global_stack_chk_guard(KernelArgumentBlock& args) {
__libc_safe_arc4random_buf(&__stack_chk_guard, sizeof(__stack_chk_guard), args);
// AT_RANDOM is a pointer to 16 bytes of randomness on the stack.
// Take the first 4/8 for the -fstack-protector implementation.
__stack_chk_guard = *reinterpret_cast<uintptr_t*>(args.getauxval(AT_RANDOM));
}
// Setup for the main thread. For dynamic executables, this is called by the

58
libc/bionic/bionic_arc4random.cpp
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@ -1,58 +0,0 @@
/*
* Copyright (C) 2016 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "private/bionic_arc4random.h"
#include <errno.h>
#include <stdlib.h>
#include <sys/auxv.h>
#include <syscall.h>
#include <unistd.h>
#include "private/KernelArgumentBlock.h"
#include "private/libc_logging.h"
void __libc_safe_arc4random_buf(void* buf, size_t n, KernelArgumentBlock& args) {
static bool have_getrandom = syscall(SYS_getrandom, nullptr, 0, 0) == -1 && errno != ENOSYS;
static bool have_urandom = access("/dev/urandom", R_OK) == 0;
static size_t at_random_bytes_consumed = 0;
if (have_getrandom || have_urandom) {
arc4random_buf(buf, n);
return;
}
if (at_random_bytes_consumed + n > 16) {
__libc_fatal("ran out of AT_RANDOM bytes, have %zu, requested %zu",
16 - at_random_bytes_consumed, n);
}
memcpy(buf, reinterpret_cast<char*>(args.getauxval(AT_RANDOM)) + at_random_bytes_consumed, n);
at_random_bytes_consumed += n;
return;
}

8
libc/bionic/setjmp_cookie.cpp
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@ -34,14 +34,14 @@
#include <sys/auxv.h>
#include <sys/cdefs.h>
#include "private/bionic_arc4random.h"
#include "private/bionic_globals.h"
#include "private/libc_logging.h"
#include "private/KernelArgumentBlock.h"
void __libc_init_setjmp_cookie(libc_globals* globals, KernelArgumentBlock& args) {
long value;
__libc_safe_arc4random_buf(&value, sizeof(value), args);
void __libc_init_setjmp_cookie(libc_globals* globals,
KernelArgumentBlock& args) {
char* random_data = reinterpret_cast<char*>(args.getauxval(AT_RANDOM));
long value = *reinterpret_cast<long*>(random_data + 8);
// Mask off the last bit to store the signal flag.
globals->setjmp_cookie = value & ~1;

45
libc/private/bionic_arc4random.h
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@ -1,45 +0,0 @@
/*
* Copyright (C) 2016 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _PRIVATE_BIONIC_ARC4RANDOM_H_
#define _PRIVATE_BIONIC_ARC4RANDOM_H_
#include <stddef.h>
#include "private/KernelArgumentBlock.h"
/*
* arc4random aborts if it's unable to fetch entropy, which is always the case
* for init on devices without getrandom(2), since /dev/random hasn't been
* created yet. Provide a wrapper function that falls back to AT_RANDOM if
* we don't have getrandom and /dev/urandom is missing.
*/
void __libc_safe_arc4random_buf(void* buf, size_t n, KernelArgumentBlock& args);
#endif