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/* Operating system specific code for generic dynamic loader functions. Linux.
Copyright (C) 2000-2002,2004-2008, 2009 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <kernel-features.h>
#include <dl-sysdep.h>
#include <fcntl.h>
#include <stdint.h>
#include <hp-timing.h>
#include <endian.h>
#ifndef MIN
# define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#ifdef SHARED
/* This is the function used in the dynamic linker to print the fatal error
message. */
static void
__attribute__ ((__noreturn__))
dl_fatal (const char *str)
{
_dl_dprintf (2, str);
_exit (1);
}
#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 (__builtin_expect (version >= 0, 1)) \
{ \
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)
{
uintptr_t ret;
#ifndef __ASSUME_AT_RANDOM
if (__builtin_expect (dl_random == NULL, 0))
{
# ifdef ENABLE_STACKGUARD_RANDOMIZE
int fd = __open ("/dev/urandom", O_RDONLY);
if (fd >= 0)
{
ssize_t reslen = __read (fd, &ret, sizeof (ret));
__close (fd);
if (reslen == (ssize_t) sizeof (ret))
return ret;
}
# endif
ret = 0;
unsigned char *p = (unsigned char *) &ret;
p[sizeof (ret) - 1] = 255;
p[sizeof (ret) - 2] = '\n';
#ifdef HP_TIMING_NOW
hp_timing_t hpt;
HP_TIMING_NOW (hpt);
hpt = (hpt & 0xffff) << 8;
ret ^= hpt;
#endif
uintptr_t stk;
/* Avoid GCC being too smart. */
asm ("" : "=r" (stk) : "r" (p));
stk &= 0x7ffff0;
#if __BYTE_ORDER == __LITTLE_ENDIAN
stk <<= (__WORDSIZE - 23);
#elif __WORDSIZE == 64
stk <<= 31;
#endif
ret ^= stk;
/* Avoid GCC being too smart. */
p = (unsigned char *) &errno;
asm ("" : "=r" (stk) : "r" (p));
stk &= 0x7fff00;
#if __BYTE_ORDER == __LITTLE_ENDIAN
stk <<= (__WORDSIZE - 29);
#else
stk >>= 8;
#endif
ret ^= stk;
}
else
#endif
/* 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, dl_random, sizeof (ret));
return ret;
}
static inline uintptr_t __attribute__ ((always_inline))
_dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)
{
uintptr_t ret;
#ifndef __ASSUME_AT_RANDOM
if (dl_random == NULL)
{
ret = stack_chk_guard;
# ifndef HP_TIMING_NONAVAIL
hp_timing_t now;
HP_TIMING_NOW (now);
ret ^= now;
# endif
}
else
#endif
memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));
return ret;
}
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