path: root/elf/dl-find_object.c

/* Locating objects in the process image.  ld.so implementation.
   Copyright (C) 2021-2023 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/>.  */

#include <assert.h>
#include <atomic.h>
#include <atomic_wide_counter.h>
#include <dl-find_object.h>
#include <dlfcn.h>
#include <ldsodefs.h>
#include <link.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

/* Fallback implementation of _dl_find_object.  It uses a linear
   search, needs locking, and is not async-signal-safe.  It is used in
   _dl_find_object prior to initialization, when called from audit
   modules.  It also serves as the reference implementation for
   _dl_find_object.  */
static int
_dl_find_object_slow (void *pc, struct dl_find_object *result)
{
  ElfW(Addr) addr = (ElfW(Addr)) pc;
  for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
    for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL;
         l = l->l_next)
      if (addr >= l->l_map_start && addr < l->l_map_end
          && (l->l_contiguous || _dl_addr_inside_object (l, addr)))
        {
          assert (ns == l->l_ns);
          struct dl_find_object_internal internal;
          _dl_find_object_from_map (l, &internal);
          _dl_find_object_to_external (&internal, result);
          return 1;
        }

  /* Object not found.  */
  return -1;
}

/* Data for the main executable.  There is usually a large gap between
   the main executable and initially loaded shared objects.  Record
   the main executable separately, to increase the chance that the
   range for the non-closeable mappings below covers only the shared
   objects (and not also the gap bet