platform_bionic/libc/bionic/setjmp_cookie.cpp
Josh Gao a170d9bfc5 Revert "Revert "Attempt to use arc4random where getauxval(AT_RANDOM) is used.""
This reverts commit 60d052dda6.

Bug: http://b/27729263
Change-Id: I7f32dc9f9a1f21fda3213f10da940821e1bdd63f
2016-11-10 17:02:45 -08:00

69 lines
2.5 KiB
C++

/*
* Copyright (C) 2015 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 <assert.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#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);
// Mask off the last bit to store the signal flag.
globals->setjmp_cookie = value & ~1;
}
extern "C" __LIBC_HIDDEN__ long __bionic_setjmp_cookie_get(long sigflag) {
if (sigflag & ~1) {
__libc_fatal("unexpected sigflag value: %ld", sigflag);
}
return __libc_globals->setjmp_cookie | sigflag;
}
// Aborts if cookie doesn't match, returns the signal flag otherwise.
extern "C" __LIBC_HIDDEN__ long __bionic_setjmp_cookie_check(long cookie) {
if (__libc_globals->setjmp_cookie != (cookie & ~1)) {
__libc_fatal("setjmp cookie mismatch");
}
return cookie & 1;
}
extern "C" __LIBC_HIDDEN__ long __bionic_setjmp_checksum_mismatch() {
__libc_fatal("setjmp checksum mismatch");
}