elf/dl-reloc-static-pie.c

   1 /* Support for relocating static PIE.
   2    Copyright (C) 2017-2021 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 #if ENABLE_STATIC_PIE
  20 /* Mark symbols hidden in static PIE for early self relocation to work.  */
  21 # pragma GCC visibility push(hidden)
  22 #include <unistd.h>
  23 #include <ldsodefs.h>
  24 #include "dynamic-link.h"
  25
  26 /* Relocate static executable with PIE.  */
  27
  28 void
  29 _dl_relocate_static_pie (void)
  30 {
  31   struct link_map *main_map = _dl_get_dl_main_map ();
  32
  33 # define STATIC_PIE_BOOTSTRAP
  34 # define BOOTSTRAP_MAP (main_map)
  35 # define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP
  36 # include "dynamic-link.h"
  37
  38   /* Figure out the run-time load address of static PIE.  */
  39   main_map->l_addr = elf_machine_load_address ();
  40
  41   /* Read our own dynamic section and fill in the info array.  */
  42   main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
  43   elf_get_dynamic_info (main_map, NULL);
  44
  45 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
  46   ELF_MACHINE_BEFORE_RTLD_RELOC (main_map->l_info);
  47 # endif
  48
  49   /* Relocate ourselves so we can do normal function calls and
  50      data access using the global offset table.  */
  51   ELF_DYNAMIC_RELOCATE (main_map, 0, 0, 0);
  52   main_map->l_relocated = 1;
  53
  54   /* Initialize _r_debug.  */
  55   struct r_debug *r = _dl_debug_initialize (0, LM_ID_BASE);
  56   r->r_state = RT_CONSISTENT;
  57
  58   /* Set up debugging before the debugger is notified for the first
  59      time.  */
  60 # ifdef ELF_MACHINE_DEBUG_SETUP
  61   /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way.  */
  62   ELF_MACHINE_DEBUG_SETUP (main_map, r);
  63 # else
  64   if (main_map->l_info[DT_DEBUG] != NULL)
  65     /* There is a DT_DEBUG entry in the dynamic section.  Fill it in
  66        with the run-time address of the r_debug structure  */
  67     main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
  68 # endif
  69 }
  70 #endif