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/* Operating system specific code for generic dynamic loader functions. Linux.
Copyright (C) 2000-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <dl-sysdep.h>
#include <endian.h>
#include <fcntl.h>
#include <stdint.h>
#include <not-cancel.h>
#ifndef MIN
# define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#define DL_SYSDEP_OSCHECK(FATAL) \
do { \
/* Test whether the kernel is new enough. This test is only performed \
if the library is not compiled to run on all kernels. */ \
\
int version = _dl_discover_osversion (); \
if (__glibc_likely (version >= 0)) \
{ \
if (__builtin_expect (GLRO(dl_osversion) == 0, 1) \
|| GLRO(dl_osversion) > version) \
GLRO(dl_osversion) = version; \
\
/* Now we can test with the required version. */ \
if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION) \
/* Not sufficent. */ \
FATAL ("FATAL: kernel too old\n"); \
} \
else if (__LINUX_KERNEL_VERSION > 0) \
FATAL ("FATAL: cannot determine kernel version\n"); \
} while (0)
static inline uintptr_t __attribute__ ((always_inline))
_dl_setup_stack_chk_guard (void *dl_random)
{
union
{
uintptr_t num;
unsigned char bytes[sizeof (uintptr_t)];
} ret;
/* We need in the moment only 8 bytes on 32-bit platforms and 16
bytes on 64-bit platforms. Therefore we can use the data
directly and not use the kernel-provided data to seed a PRNG. */
memcpy (ret.bytes, dl_random, sizeof (ret));
#if BYTE_ORDER == LITTLE_ENDIAN
ret.num &= ~(uintptr_t) 0xff;
#elif BYTE_ORDER == BIG_ENDIAN
ret.num &= ~((uintptr_t) 0xff << (8 * (sizeof (ret) - 1)));
#else
# error "BYTE_ORDER unknown"
#endif
return ret.num;
}
static inline uintptr_t __attribute__ ((always_inline))
_dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)
{
uintptr_t ret;
memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));
return ret;
}
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