| /* |
| * Copyright (C) 2012 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_SSP_H |
| #define _PRIVATE_SSP_H |
| |
| #include <errno.h> |
| #include <sys/cdefs.h> |
| |
| __BEGIN_DECLS |
| |
| /** WARNING WARNING WARNING |
| ** |
| ** This header file is *NOT* part of the public Bionic ABI/API |
| ** and should not be used/included by user-serviceable parts of |
| ** the system (e.g. applications). |
| **/ |
| |
| /* GCC uses this on ARM and MIPS. */ |
| extern void* __stack_chk_guard; |
| |
| /* GCC calls this if a stack guard check fails. */ |
| extern void __stack_chk_fail(); |
| |
| __inline__ static void* __attribute__((always_inline)) __generate_stack_chk_guard(void) { |
| union { |
| uintptr_t value; |
| char bytes[sizeof(uintptr_t)]; |
| } u; |
| |
| /* Try pulling random bytes from /dev/urandom. */ |
| int fd = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY)); |
| if (fd != -1) { |
| ssize_t byte_count = TEMP_FAILURE_RETRY(read(fd, &u.bytes, sizeof(u))); |
| close(fd); |
| if (byte_count == sizeof(u)) { |
| return (void*) u.value; |
| } |
| } |
| |
| /* If that failed, switch to 'terminator canary'. */ |
| u.bytes[0] = 0; |
| u.bytes[1] = 0; |
| u.bytes[2] = '\n'; |
| u.bytes[3] = 255; |
| return (void*) u.value; |
| } |
| |
| __END_DECLS |
| |
| #endif |