sysdeps/generic/dl-protected.h

   1 /* Support for STV_PROTECTED visibility.  Generic version.
   2    Copyright (C) 2021-2023 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _DL_PROTECTED_H
  20 #define _DL_PROTECTED_H
  21
  22 static inline void __attribute__ ((always_inline))
  23 _dl_check_protected_symbol (const char *undef_name,
  24                             const struct link_map *undef_map,
  25                             const ElfW(Sym) *ref,
  26                             const struct link_map *map,
  27                             int type_class)
  28 {
  29   if (undef_map == NULL || undef_map->l_type != lt_executable)
  30     return;
  31
  32   if (type_class & ELF_RTYPE_CLASS_COPY)
  33     /* Disallow copy relocations in executable against protected
  34        data symbols in a shared object which needs indirect external
  35        access.  */
  36     _dl_error_printf ("warning: copy relocation against non-copyable "
  37                       "protected symbol `%s' in `%s'\n",
  38                       undef_name, map->l_name);
  39   else if ((type_class & ELF_RTYPE_CLASS_PLT) && ref->st_value != 0
  40            && ref->st_shndx == SHN_UNDEF)
  41     /* Disallow non-zero symbol values of undefined symbols in
  42        executable, which are used as the function pointer, against
  43        protected function symbols in a shared object with indirect
  44        external access.  */
  45     _dl_error_printf (
  46         "warning: direct reference to "
  47         "protected function `%s' in `%s' may break pointer equality\n",
  48         undef_name, map->l_name);
  49   else
  50     return;
  51
  52   if (map->l_1_needed & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS)
  53     _dl_signal_error (
  54         0, map->l_name, undef_name,
  55         N_ ("error due to GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS"));
  56 }
  57
  58 #endif /* _DL_PROTECTED_H */