sysdeps/unix/sysv/linux/dl-osinfo.h

   1 /* Operating system specific code for generic dynamic loader functions.  Linux.
   2    Copyright (C) 2000-2002,2004-2007,2008 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <kernel-features.h>
  21 #include <dl-sysdep.h>
  22 #include <fcntl.h>
  23 #include <stdint.h>
  24
  25 #ifndef MIN
  26 # define MIN(a,b) (((a)<(b))?(a):(b))
  27 #endif
  28
  29 #ifdef SHARED
  30 /* This is the function used in the dynamic linker to print the fatal error
  31    message.  */
  32 static inline void
  33 __attribute__ ((__noreturn__))
  34 dl_fatal (const char *str)
  35 {
  36   _dl_dprintf (2, str);
  37   _exit (1);
  38 }
  39 #endif
  40
  41 #define DL_SYSDEP_OSCHECK(FATAL)                                              \
  42   do {                                                                        \
  43     /* Test whether the kernel is new enough.  This test is only performed    \
  44        if the library is not compiled to run on all kernels.  */              \
  45                                                                               \
  46     int version = _dl_discover_osversion ();                                  \
  47     if (__builtin_expect (version >= 0, 1))                                   \
  48       {                                                                       \
  49         if (__builtin_expect (GLRO(dl_osversion) == 0, 1)                     \
  50             || GLRO(dl_osversion) > version)                                  \
  51           GLRO(dl_osversion) = version;                                       \
  52                                                                               \
  53         /* Now we can test with the required version.  */                     \
  54         if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION)   \
  55           /* Not sufficent.  */                                               \
  56           FATAL ("FATAL: kernel too old\n");                                  \
  57       }                                                                       \
  58     else if (__LINUX_KERNEL_VERSION > 0)                                      \
  59       FATAL ("FATAL: cannot determine kernel version\n");                     \
  60   } while (0)
  61
  62 static inline uintptr_t __attribute__ ((always_inline))
  63 _dl_setup_stack_chk_guard (void)
  64 {
  65   uintptr_t ret;
  66 #ifdef ENABLE_STACKGUARD_RANDOMIZE
  67   int fd = __open ("/dev/urandom", O_RDONLY);
  68   if (fd >= 0)
  69     {
  70       ssize_t reslen = __read (fd, &ret, sizeof (ret));
  71       __close (fd);
  72       if (reslen == (ssize_t) sizeof (ret))
  73         return ret;
  74     }
  75 #endif
  76   ret = 0;
  77   unsigned char *p = (unsigned char *) &ret;
  78   p[sizeof (ret) - 1] = 255;
  79   p[sizeof (ret) - 2] = '\n';
  80   return ret;
  81 }