elf/dl-reloc-static-pie.c

   1 /* Support for relocating static PIE.
   2    Copyright (C) 2017-2024 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 <assert.h>
  23 #include <unistd.h>
  24 #include <ldsodefs.h>
  25
  26 #include <dl-machine.h>
  27 #include <dl-debug.h>
  28
  29 #define RESOLVE_MAP(map, scope, sym, version, flags) map
  30 #include "dynamic-link.h"
  31 #include "get-dynamic-info.h"
  32
  33 /* Relocate static executable with PIE.  */
  34
  35 void
  36 _dl_relocate_static_pie (void)
  37 {
  38   struct link_map *main_map = _dl_get_dl_main_map ();
  39
  40   /* Figure out the run-time load address of static PIE.  */
  41   main_map->l_addr = elf_machine_load_address ();
  42
  43   /* Read our own dynamic section and fill in the info array.  */
  44   main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
  45
  46   const ElfW(Phdr) *ph, *phdr = GL(dl_phdr);
  47   size_t phnum = GL(dl_phnum);
  48   for (ph = phdr; ph < &phdr[phnum]; ++ph)
  49     if (ph->p_type == PT_DYNAMIC)
  50       {
  51         main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
  52         break;
  53       }
  54
  55   elf_get_dynamic_info (main_map, false, true);
  56
  57 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
  58   ELF_MACHINE_BEFORE_RTLD_RELOC (main_map, main_map->l_info);
  59 # endif
  60
  61   /* Relocate ourselves so we can do normal function calls and
  62      data access using the global offset table.  */
  63   ELF_DYNAMIC_RELOCATE (main_map, NULL, 0, 0, 0);
  64   main_map->l_relocated = 1;
  65
  66   /* Initialize _r_debug_extended.  */
  67   struct r_debug *r = _dl_debug_initialize (0, LM_ID_BASE);
  68   r->r_state = RT_CONSISTENT;
  69
  70   /* Set up debugging before the debugger is notified for the first
  71      time.  */
  72   elf_setup_debug_entry (main_map, r);
  73 }
  74 #endif