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 <assert.h>
23 #include <unistd.h>
24 #include <ldsodefs.h>
25
26 #include <dl-machine.h>
27
28 #define RESOLVE_MAP(map, scope, sym, version, flags) map
29 #include "dynamic-link.h"
30 #include "get-dynamic-info.h"
31
32 /* Relocate static executable with PIE. */
33
34 void
_dl_relocate_static_pie(void)35 _dl_relocate_static_pie (void)
36 {
37 struct link_map *main_map = _dl_get_dl_main_map ();
38
39 /* Figure out the run-time load address of static PIE. */
40 main_map->l_addr = elf_machine_load_address ();
41
42 /* Read our own dynamic section and fill in the info array. */
43 main_map->l_ld = ((void *) main_map->l_addr + elf_machine_dynamic ());
44
45 const ElfW(Phdr) *ph, *phdr = GL(dl_phdr);
46 size_t phnum = GL(dl_phnum);
47 for (ph = phdr; ph < &phdr[phnum]; ++ph)
48 if (ph->p_type == PT_DYNAMIC)
49 {
50 main_map->l_ld_readonly = (ph->p_flags & PF_W) == 0;
51 break;
52 }
53
54 elf_get_dynamic_info (main_map, false, true);
55
56 # ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
57 ELF_MACHINE_BEFORE_RTLD_RELOC (main_map, main_map->l_info);
58 # endif
59
60 /* Relocate ourselves so we can do normal function calls and
61 data access using the global offset table. */
62 ELF_DYNAMIC_RELOCATE (main_map, NULL, 0, 0, 0);
63 main_map->l_relocated = 1;
64
65 /* Initialize _r_debug_extended. */
66 struct r_debug *r = _dl_debug_initialize (0, LM_ID_BASE);
67 r->r_state = RT_CONSISTENT;
68
69 /* Set up debugging before the debugger is notified for the first
70 time. */
71 # ifdef ELF_MACHINE_DEBUG_SETUP
72 /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way. */
73 ELF_MACHINE_DEBUG_SETUP (main_map, r);
74 # else
75 if (main_map->l_info[DT_DEBUG] != NULL)
76 /* There is a DT_DEBUG entry in the dynamic section. Fill it in
77 with the run-time address of the r_debug structure */
78 main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
79 # endif
80 }
81 #endif
82