Revert "Attempt to use arc4random where getauxval(AT_RANDOM) is used."
This reverts commit 78a52f19bb207d1c736f1d5362e01f338d78645f.
Change-Id: Ia72501ad0b81e894d67e5ce59b597397c11acfa5
diff --git a/libc/bionic/__libc_init_main_thread.cpp b/libc/bionic/__libc_init_main_thread.cpp
index 0647387..2643eee 100644
--- a/libc/bionic/__libc_init_main_thread.cpp
+++ b/libc/bionic/__libc_init_main_thread.cpp
@@ -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 @@
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
diff --git a/libc/bionic/bionic_arc4random.cpp b/libc/bionic/bionic_arc4random.cpp
deleted file mode 100644
index d20cb68..0000000
--- a/libc/bionic/bionic_arc4random.cpp
+++ /dev/null
@@ -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;
-}
diff --git a/libc/bionic/setjmp_cookie.cpp b/libc/bionic/setjmp_cookie.cpp
index 4fa68c2..3be675a 100644
--- a/libc/bionic/setjmp_cookie.cpp
+++ b/libc/bionic/setjmp_cookie.cpp
@@ -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;