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98bb2f1cd2
* sysdeps/generic/dl-osinfo.h (_dl_setup_stack_chk_guard): Fix masking out of the most significant byte of random value used. * sysdeps/unix/sysv/linux/dl-osinfo.h (_dl_setup_stack_chk_guard): Fix coding style in previous change.
127 lines
3.8 KiB
C
127 lines
3.8 KiB
C
/* Operating system specific code for generic dynamic loader functions. Linux.
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Copyright (C) 2000-2002,2004-2009,2011 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, see
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<http://www.gnu.org/licenses/>. */
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#include <kernel-features.h>
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#include <dl-sysdep.h>
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#include <endian.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <not-cancel.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 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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union
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{
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uintptr_t num;
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unsigned char bytes[sizeof (uintptr_t)];
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} 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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const size_t filllen = sizeof (ret.bytes) - 1;
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ret.num = 0;
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# ifdef ENABLE_STACKGUARD_RANDOMIZE
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int fd = open_not_cancel_2 ("/dev/urandom", O_RDONLY);
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if (fd >= 0)
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{
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ssize_t reslen = read_not_cancel (fd, ret.bytes + 1, filllen);
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close_not_cancel_no_status (fd);
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if (reslen == (ssize_t) filllen)
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return ret.num;
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}
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# endif
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ret.bytes[filllen] = 255;
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ret.bytes[filllen - 1] = '\n';
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}
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else
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#endif
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{
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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.bytes, dl_random, sizeof (ret));
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#if BYTE_ORDER == LITTLE_ENDIAN
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ret.num &= ~(uintptr_t) 0xff;
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#elif BYTE_ORDER == BIG_ENDIAN
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ret.num &= ~((uintptr_t) 0xff << (8 * (sizeof (ret) - 1)));
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#else
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# error "BYTE_ORDER unknown"
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#endif
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}
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return ret.num;
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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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