elf/dl-caller.c

   1 /* Check whether caller comes from the right place.
   2    Copyright (C) 2004-2017 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <ldsodefs.h>
  21 #include <stddef.h>
  22 #include <caller.h>
  23 #include <gnu/lib-names.h>
  24
  25
  26 int
  27 attribute_hidden
  28 _dl_check_caller (const void *caller, enum allowmask mask)
  29 {
  30   static const char expected1[] = LIBC_SO;
  31   static const char expected2[] = LIBDL_SO;
  32 #ifdef LIBPTHREAD_SO
  33   static const char expected3[] = LIBPTHREAD_SO;
  34 #endif
  35   static const char expected4[] = LD_SO;
  36
  37   for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
  38     for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
  39          l = l->l_next)
  40       if (caller >= (const void *) l->l_map_start
  41           && caller < (const void *) l->l_text_end)
  42         {
  43           /* The address falls into this DSO's address range.  Check the
  44              name.  */
  45           if ((mask & allow_libc) && strcmp (expected1, l->l_name) == 0)
  46             return 0;
  47           if ((mask & allow_libdl) && strcmp (expected2, l->l_name) == 0)
  48             return 0;
  49 #ifdef LIBPTHREAD_SO
  50           if ((mask & allow_libpthread) && strcmp (expected3, l->l_name) == 0)
  51             return 0;
  52 #endif
  53           if ((mask & allow_ldso) && strcmp (expected4, l->l_name) == 0)
  54             return 0;
  55
  56           struct libname_list *runp = l->l_libname;
  57
  58           while (runp != NULL)
  59             {
  60               if ((mask & allow_libc) && strcmp (expected1, runp->name) == 0)
  61                 return 0;
  62               if ((mask & allow_libdl) && strcmp (expected2, runp->name) == 0)
  63                 return 0;
  64 #ifdef LIBPTHREAD_SO
  65               if ((mask & allow_libpthread)
  66                   && strcmp (expected3, runp->name) == 0)
  67                 return 0;
  68 #endif
  69               if ((mask & allow_ldso) && strcmp (expected4, runp->name) == 0)
  70                 return 0;
  71
  72               runp = runp->next;
  73             }
  74
  75           break;
  76         }
  77
  78   /* Maybe the dynamic linker is not yet on the list.  */
  79   if ((mask & allow_ldso) != 0
  80       && caller >= (const void *) GL(dl_rtld_map).l_map_start
  81       && caller < (const void *) GL(dl_rtld_map).l_text_end)
  82     return 0;
  83
  84   /* No valid caller.  */
  85   return 1;
  86 }