1  /* Post-processing of a symbol produced by dlsym, dlvsym.
       2     Copyright (C) 1999-2023 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  
      20  /* Return the link map containing the caller address.  */
      21  static struct link_map *
      22  _dl_sym_find_caller_link_map (ElfW(Addr) caller)
      23  {
      24    struct link_map *l = _dl_find_dso_for_object (caller);
      25    if (l != NULL)
      26      return l;
      27    else
      28      /* If the address is not recognized the call comes from the main
      29         program (we hope).  */
      30      return GL(dl_ns)[LM_ID_BASE]._ns_loaded;
      31  }
      32  
      33  /* Translates RESULT, *REF, VALUE into a symbol address from the point
      34     of view of MATCH.  Performs IFUNC resolution and auditing if
      35     necessary.  If MATCH is NULL, CALLER is used to determine it.  */
      36  static void *
      37  _dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value,
      38                ElfW(Addr) caller, struct link_map *match)
      39  {
      40    /* Resolve indirect function address.  */
      41    if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))
      42      {
      43        DL_FIXUP_VALUE_TYPE fixup
      44          = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);
      45        fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));
      46        value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);
      47      }
      48  
      49  #ifdef SHARED
      50    /* Auditing checkpoint: we have a new binding.  Provide the
      51       auditing libraries the possibility to change the value and
      52       tell us whether further auditing is wanted.  */
      53    if (__glibc_unlikely (GLRO(dl_naudit) > 0))
      54      {
      55        if (match == NULL)
      56          match = _dl_sym_find_caller_link_map (caller);
      57        _dl_audit_symbind_alt (match, ref, &value, result);
      58      }
      59  #endif
      60    return value;
      61  }