platform_bionic/libc/private/bionic_ssp.h
Nick Kralevich 36bd371e26 Revert "stack protector: use AT_RANDOM"
The AT_RANDOM changes broke setuid / setgid executables
such as "ping". When the linker executes a setuid program,
it cleans the environment, removing any invalid environment
entries, and adding "NULL"s to the end of the environment
array for each removed variable. Later on, we try to determine
the location of the aux environment variable, and get tripped
up by these extra NULLs.

Reverting this patch will get setuid executables working again,
but getauxval() is still broken for setuid programs because of
this bug.

This reverts commit e3a49a8661.

Change-Id: I05c58a896b1fe32cfb5d95d43b096045cda0aa4a
2013-01-16 13:16:42 -08:00

76 lines
2.4 KiB
C

/*
* 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