summary refs log tree commit diff
path: root/elf/dl-reloc.c
blob: c829de797fa591515269483dc36b892ca5a213b9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
/* Relocate a shared object and resolve its references to other loaded objects.
   Copyright (C) 1995,96,97,98,99,2000,2001 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <unistd.h>
#include <ldsodefs.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "dynamic-link.h"


void
_dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
		     int lazy, int consider_profiling)
{
  if (l->l_relocated)
    return;

  /* If DT_BIND_NOW is set relocate all references in this object.  We
     do not do this if we are profiling, of course.  */
  if (!consider_profiling
      && __builtin_expect (l->l_info[DT_BIND_NOW] != NULL, 0))
    lazy = 0;

  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_RELOC, 0))
    _dl_printf ("\nrelocation processing: %s%s\n",
		l->l_name[0] ? l->l_name : _dl_argv[0], lazy ? " (lazy)" : "");

  if (__builtin_expect (l->l_info[DT_TEXTREL] != NULL, 0))
    {
      /* Bletch.  We must make read-only segments writable
	 long enough to relocate them.  */
      const ElfW(Phdr) *ph;
      for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph)
	if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0)
	  {
	    caddr_t mapstart = ((caddr_t) l->l_addr +
				(ph->p_vaddr & ~(_dl_pagesize - 1)));
	    caddr_t mapend = ((caddr_t) l->l_addr +
			      ((ph->p_vaddr + ph->p_memsz + _dl_pagesize - 1)
			       & ~(_dl_pagesize - 1)));
	    if (__builtin_expect (__mprotect (mapstart, mapend - mapstart,
					      PROT_READ|PROT_WRITE), 0) < 0)
	      _dl_signal_error (errno, l->l_name, N_("\
cannot make segment writable for relocation"));
	  }
    }

  {
    /* Do the actual relocation of the object's GOT and other data.  */

    /* String table object symbols.  */
    const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);

    /* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code.  */
#define RESOLVE_MAP(ref, version, flags) \
    (ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL			      \
     ? ((version) != NULL && (version)->hash != 0			      \
	? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, l, (ref),    \
				       scope, (version), (flags), 0)	      \
	: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), scope,	      \
			     (flags), 0))				      \
     : l)
#define RESOLVE(ref, version, flags) \
    (ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL			      \
     ? ((version) != NULL && (version)->hash != 0			      \
	? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, l, (ref),    \
				       scope, (version), (flags), 0)	      \
	: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), scope,	      \
			     (flags), 0))				      \
     : l->l_addr)

#include "dynamic-link.h"
    ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling);

    if (__builtin_expect (_dl_profile != NULL, 0))
      {
	/* Allocate the array which will contain the already found
	   relocations.  If the shared object lacks a PLT (for example
	   if it only contains lead function) the l_info[DT_PLTRELSZ]
	   will be NULL.  */
	if (l->l_info[DT_PLTRELSZ] == NULL)
	  _dl_fatal_printf ("%s: profiler found no PLTREL in object %s\n",
			    _dl_argv[0] ?: "<program name unknown>",
			    l->l_name);

	l->l_reloc_result =
	  (ElfW(Addr) *) calloc (sizeof (ElfW(Addr)),
				 l->l_info[DT_PLTRELSZ]->d_un.d_val);
	if (l->l_reloc_result == NULL)
	  _dl_fatal_printf ("\
%s: profiler out of memory shadowing PLTREL of %s\n",
			    _dl_argv[0] ?: "<program name unknown>",
			    l->l_name);
      }
  }

  /* Mark the object so we know this work has been done.  */
  l->l_relocated = 1;

  /* DT_TEXTREL is now in level 2 and might phase out at some time.
     But we rewrite the DT_FLAGS entry to make testing easier and
     therefore it will be available at all time.  */
  if (__builtin_expect (l->l_info[DT_TEXTREL] != NULL, 0))
    {
      /* Undo the protection change we made before relocating.  */
      const ElfW(Phdr) *ph;
      for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph)
	if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0)
	  {
	    caddr_t mapstart = ((caddr_t) l->l_addr +
				(ph->p_vaddr & ~(_dl_pagesize - 1)));
	    caddr_t mapend = ((caddr_t) l->l_addr +
			      ((ph->p_vaddr + ph->p_memsz + _dl_pagesize - 1)
			       & ~(_dl_pagesize - 1)));
	    extern unsigned char _dl_pf_to_prot[8];
	    int prot;

	    if ((PF_R | PF_W | PF_X) == 7
		&& (PROT_READ | PROT_WRITE | PROT_EXEC) == 7)
	      prot = _dl_pf_to_prot[ph->p_flags & (PF_R | PF_X)];
	    else
	      {
		prot = 0;
		if (ph->p_flags & PF_R)
		  prot |= PROT_READ;
		if (ph->p_flags & PF_X)
		  prot |= PROT_EXEC;
	      }

	    if (__builtin_expect (__mprotect (mapstart, mapend - mapstart,
					      prot), 0) < 0)
	      _dl_signal_error (errno, l->l_name,
				N_("can't restore segment prot after reloc"));

#ifdef CLEAR_CACHE
	    CLEAR_CACHE (mapstart, mapend);
#endif
	  }
    }
}

#include "../stdio-common/_itoa.h"
#define DIGIT(b)	_itoa_lower_digits[(b) & 0xf];

void
internal_function
_dl_reloc_bad_type (struct link_map *map, uint_fast8_t type, int plt)
{
  extern const char _itoa_lower_digits[];
  if (plt)
    {
      /* XXX We cannot translate the message.  */
      static char msg[] = "unexpected PLT reloc type 0x??";
      msg[sizeof msg - 3] = DIGIT(type >> 4);
      msg[sizeof msg - 2] = DIGIT(type);
      _dl_signal_error (0, map->l_name, msg);
    }
  else
    {
      /* XXX We cannot translate the message.  */
      static char msg[] = "unexpected reloc type 0x??";
      msg[sizeof msg - 3] = DIGIT(type >> 4);
      msg[sizeof msg - 2] = DIGIT(type);
      _dl_signal_error (0, map->l_name, msg);
    }
}