| /* Operating system specific code for generic dynamic loader functions. Linux. |
| Copyright (C) 2000-2014 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 |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <kernel-features.h> |
| #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 (__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) |
| { |
| union |
| { |
| uintptr_t num; |
| unsigned char bytes[sizeof (uintptr_t)]; |
| } ret; |
| |
| #ifndef __ASSUME_AT_RANDOM |
| if (__builtin_expect (dl_random == NULL, 0)) |
| { |
| const size_t filllen = sizeof (ret.bytes) - 1; |
| ret.num = 0; |
| # ifdef ENABLE_STACKGUARD_RANDOMIZE |
| int fd = open_not_cancel_2 ("/dev/urandom", O_RDONLY); |
| if (fd >= 0) |
| { |
| ssize_t reslen = read_not_cancel (fd, ret.bytes + 1, filllen); |
| close_not_cancel_no_status (fd); |
| if (reslen == (ssize_t) filllen) |
| return ret.num; |
| } |
| # endif |
| ret.bytes[filllen] = 255; |
| ret.bytes[filllen - 1] = '\n'; |
| } |
| 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.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; |
| #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; |
| } |