gdb/nat/linux-personality.c

   1 /* Disable address space randomization based on inferior personality.
   2
   3    Copyright (C) 2008-2015 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "common-defs.h"
  21 #include "nat/linux-personality.h"
  22
  23 #ifdef HAVE_PERSONALITY
  24 # include <sys/personality.h>
  25 # if !HAVE_DECL_ADDR_NO_RANDOMIZE
  26 #  define ADDR_NO_RANDOMIZE 0x0040000
  27 # endif /* ! HAVE_DECL_ADDR_NO_RANDOMIZE */
  28 #endif /* HAVE_PERSONALITY */
  29
  30 #ifdef HAVE_PERSONALITY
  31
  32 /* Restore address space randomization of the inferior.  ARG is the
  33    original inferior's personality value before the address space
  34    randomization was disabled.  */
  35
  36 static void
  37 restore_personality (void *arg)
  38 {
  39   int personality_orig = (int) (uintptr_t) arg;
  40
  41   errno = 0;
  42   personality (personality_orig);
  43   if (errno != 0)
  44     warning (_("Error restoring address space randomization: %s"),
  45              safe_strerror (errno));
  46 }
  47 #endif /* HAVE_PERSONALITY */
  48
  49 /* Return a cleanup responsible for restoring the inferior's
  50    personality (and restoring the inferior's address space
  51    randomization) if HAVE_PERSONALITY and if PERSONALITY_SET is not
  52    zero; return a null cleanup if not HAVE_PERSONALITY or if
  53    PERSONALITY_SET is zero.  */
  54
  55 static struct cleanup *
  56 make_disable_asr_cleanup (int personality_set, int personality_orig)
  57 {
  58 #ifdef HAVE_PERSONALITY
  59   if (personality_set != 0)
  60     return make_cleanup (restore_personality,
  61                          (void *) (uintptr_t) personality_orig);
  62 #endif /* HAVE_PERSONALITY */
  63
  64   return make_cleanup (null_cleanup, NULL);
  65 }
  66
  67 /* See comment on nat/linux-personality.h.  */
  68
  69 struct cleanup *
  70 maybe_disable_address_space_randomization (int disable_randomization)
  71 {
  72   int personality_orig = 0;
  73   int personality_set = 0;
  74
  75 #ifdef HAVE_PERSONALITY
  76   if (disable_randomization)
  77     {
  78       errno = 0;
  79       personality_orig = personality (0xffffffff);
  80       if (errno == 0 && !(personality_orig & ADDR_NO_RANDOMIZE))
  81         {
  82           personality_set = 1;
  83           personality (personality_orig | ADDR_NO_RANDOMIZE);
  84         }
  85       if (errno != 0 || (personality_set
  86                          && !(personality (0xffffffff) & ADDR_NO_RANDOMIZE)))
  87         warning (_("Error disabling address space randomization: %s"),
  88                  safe_strerror (errno));
  89     }
  90 #endif /* HAVE_PERSONALITY */
  91
  92   return make_disable_asr_cleanup (personality_set,
  93                                    personality_orig);
  94 }