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one parameter. If non-NULL use it to initialize return value. (_dl_setup_pointer_guard): New function. * sysdeps/unix/sysv/linux/dl-osinfo.h: Likewise. * sysdeps/generic/ldsodefs.h: Declare _dl_random. * elf/rtld.c (security_init): Pass _dl_random to _dl_setup_stack_chk_guard. Call _dl_setup_pointer_guard to initialize pointer_chk_guard. * elf/dl-sysdep.c (_dl_random): New variable. (_dl_sysdep_start): Handle AT_RANDOM. (_dl_show_auxv): Likewise. * elf/dl-support.c (_dl_random): New variable. (_dl_aux_init): Handle AT_RANDOM. * csu/libc-start.c [!SHARED] (libc_start_main): Pass _dl_random to _dl_setup_stack_chk_guard. * elf/elf.h (AT_RANDOM): Define AT_BASE_PLATFORM and AT_RANDOM.
112 lines
3.5 KiB
C
112 lines
3.5 KiB
C
/* Operating system specific code for generic dynamic loader functions. Linux.
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Copyright (C) 2000-2002,2004-2008, 2009 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <kernel-features.h>
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#include <dl-sysdep.h>
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#include <fcntl.h>
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#include <stdint.h>
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#ifndef MIN
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# define MIN(a,b) (((a)<(b))?(a):(b))
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#endif
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#ifdef SHARED
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/* This is the function used in the dynamic linker to print the fatal error
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message. */
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static inline void
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__attribute__ ((__noreturn__))
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dl_fatal (const char *str)
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{
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_dl_dprintf (2, str);
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_exit (1);
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}
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#endif
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#define DL_SYSDEP_OSCHECK(FATAL) \
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do { \
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/* Test whether the kernel is new enough. This test is only performed \
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if the library is not compiled to run on all kernels. */ \
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\
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int version = _dl_discover_osversion (); \
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if (__builtin_expect (version >= 0, 1)) \
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{ \
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if (__builtin_expect (GLRO(dl_osversion) == 0, 1) \
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|| GLRO(dl_osversion) > version) \
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GLRO(dl_osversion) = version; \
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\
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/* Now we can test with the required version. */ \
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if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION) \
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/* Not sufficent. */ \
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FATAL ("FATAL: kernel too old\n"); \
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} \
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else if (__LINUX_KERNEL_VERSION > 0) \
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FATAL ("FATAL: cannot determine kernel version\n"); \
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} while (0)
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static inline uintptr_t __attribute__ ((always_inline))
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_dl_setup_stack_chk_guard (void *dl_random)
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{
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uintptr_t ret;
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#ifndef __ASSUME_AT_RANDOM
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if (__builtin_expect (dl_random == NULL, 0))
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{
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# ifdef ENABLE_STACKGUARD_RANDOMIZE
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int fd = __open ("/dev/urandom", O_RDONLY);
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if (fd >= 0)
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{
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ssize_t reslen = __read (fd, &ret, sizeof (ret));
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__close (fd);
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if (reslen == (ssize_t) sizeof (ret))
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return ret;
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}
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# endif
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ret = 0;
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unsigned char *p = (unsigned char *) &ret;
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p[sizeof (ret) - 1] = 255;
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p[sizeof (ret) - 2] = '\n';
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}
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else
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#endif
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/* We need in the moment only 8 bytes on 32-bit platforms and 16
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bytes on 64-bit platforms. Therefore we can use the data
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directly and not use the kernel-provided data to seed a PRNG. */
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memcpy (&ret, dl_random, sizeof (ret));
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return ret;
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}
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static inline uintptr_t __attribute__ ((always_inline))
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_dl_setup_pointer_guard (void *dl_random, uintptr_t stack_chk_guard)
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{
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uintptr_t ret;
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#ifndef __ASSUME_AT_RANDOM
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if (dl_random == NULL)
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{
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ret = stack_chk_guard;
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# ifndef HP_TIMING_NONAVAIL
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hp_timing_t now;
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HP_TIMING_NOW (now);
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ret ^= now;
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# endif
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}
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else
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#endif
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memcpy (&ret, (char *) dl_random + sizeof (ret), sizeof (ret));
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return ret;
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}
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