/* Post-processing of a symbol produced by dlsym, dlvsym.

   Copyright (C) 1999-2020 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <https://www.gnu.org/licenses/>.  */

/* Return the link map containing the caller address.  */

static struct link_map *

_dl_sym_find_caller_link_map (ElfW(Addr) caller)

{

  struct link_map *l = _dl_find_dso_for_object (caller);

  if (l != NULL)

    return l;

  else

    /* If the address is not recognized the call comes from the main

       program (we hope).  */

    return GL(dl_ns)[LM_ID_BASE]._ns_loaded;

}

/* Translates RESULT, *REF, VALUE into a symbol address from the point

   of view of MATCH.  Performs IFUNC resolution and auditing if

   necessary.  If MATCH is NULL, CALLER is used to determine it.  */

static void *

_dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value,

              ElfW(Addr) caller, struct link_map *match)

{

  /* Resolve indirect function address.  */

  if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC))

    {

      DL_FIXUP_VALUE_TYPE fixup

        = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value);

      fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup));

      value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup);

    }

#ifdef SHARED

  /* Auditing checkpoint: we have a new binding.  Provide the

     auditing libraries the possibility to change the value and

     tell us whether further auditing is wanted.  */

  if (__glibc_unlikely (GLRO(dl_naudit) > 0))

    {

      const char *strtab = (const char *) D_PTR (result,

                                                 l_info[DT_STRTAB]);

      /* Compute index of the symbol entry in the symbol table of

         the DSO with the definition.  */

      unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result,

                                                     l_info[DT_SYMTAB]));

      if (match == NULL)

        match = _dl_sym_find_caller_link_map (caller);

      if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0)

        {

          unsigned int altvalue = 0;

          struct audit_ifaces *afct = GLRO(dl_audit);

          /* Synthesize a symbol record where the st_value field is

             the result.  */

          ElfW(Sym) sym = *ref;

          sym.st_value = (ElfW(Addr)) value;

          for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)

            {

              struct auditstate *match_audit

                = link_map_audit_state (match, cnt);

              struct auditstate *result_audit

                = link_map_audit_state (result, cnt);

              if (afct->symbind != NULL

                  && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0

                      || ((result_audit->bindflags & LA_FLG_BINDTO)

                          != 0)))

                {

                  unsigned int flags = altvalue | LA_SYMB_DLSYM;

                  uintptr_t new_value

                    = afct->symbind (&sym, ndx,

                                     &match_audit->cookie,

                                     &result_audit->cookie,

                                     &flags, strtab + ref->st_name);

                  if (new_value != (uintptr_t) sym.st_value)

                    {

                      altvalue = LA_SYMB_ALTVALUE;

                      sym.st_value = new_value;

                    }

                }

              afct = afct->next;

            }

          value = (void *) sym.st_value;

        }

    }

#endif

  return value;

}