aboutsummaryrefslogtreecommitdiff
path: root/bfd/elf-properties.c
blob: cd44ed6194bbfbb9d8a519af05e9ee75d015d678 (plain)
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
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
/* ELF program property support.
   Copyright (C) 2017-2018 Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

/* GNU program property draft is at:

   https://github.com/hjl-tools/linux-abi/wiki/property-draft.pdf
 */

#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "elf-bfd.h"

/* Get a property, allocate a new one if needed.  */

elf_property *
_bfd_elf_get_property (bfd *abfd, unsigned int type, unsigned int datasz)
{
  elf_property_list *p, **lastp;

  if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
    {
      /* Never should happen.  */
      abort ();
    }

  /* Keep the property list in order of type.  */
  lastp = &elf_properties (abfd);
  for (p = *lastp; p; p = p->next)
    {
      /* Reuse the existing entry.  */
      if (type == p->property.pr_type)
	{
	  if (datasz > p->property.pr_datasz)
	    {
	      /* This can happen when mixing 32-bit and 64-bit objects.  */
	      p->property.pr_datasz = datasz;
	    }
	  return &p->property;
	}
      else if (type < p->property.pr_type)
	break;
      lastp = &p->next;
    }
  p = (elf_property_list *) bfd_alloc (abfd, sizeof (*p));
  if (p == NULL)
    {
      _bfd_error_handler (_("%pB: out of memory in _bfd_elf_get_property"),
			  abfd);
      _exit (EXIT_FAILURE);
    }
  memset (p, 0, sizeof (*p));
  p->property.pr_type = type;
  p->property.pr_datasz = datasz;
  p->next = *lastp;
  *lastp = p;
  return &p->property;
}

/* Parse GNU properties.  */

bfd_boolean
_bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note)
{
  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
  unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
  bfd_byte *ptr = (bfd_byte *) note->descdata;
  bfd_byte *ptr_end = ptr + note->descsz;

  if (note->descsz < 8 || (note->descsz % align_size) != 0)
    {
bad_size:
      _bfd_error_handler
	(_("warning: %pB: corrupt GNU_PROPERTY_TYPE (%ld) size: %#lx"),
	 abfd, note->type, note->descsz);
      return FALSE;
    }

  while (ptr != ptr_end)
    {
      unsigned int type;
      unsigned int datasz;
      elf_property *prop;

      if ((size_t) (ptr_end - ptr) < 8)
	goto bad_size;

      type = bfd_h_get_32 (abfd, ptr);
      datasz = bfd_h_get_32 (abfd, ptr + 4);
      ptr += 8;

      if (datasz > (size_t) (ptr_end - ptr))
	{
	  _bfd_error_handler
	    (_("warning: %pB: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x"),
	     abfd, note->type, type, datasz);
	  /* Clear all properties.  */
	  elf_properties (abfd) = NULL;
	  return FALSE;
	}

      if (type >= GNU_PROPERTY_LOPROC)
	{
	  if (bed->elf_machine_code == EM_NONE)
	    {
	      /* Ignore processor-specific properties with generic ELF
		 target vector.  They should be handled by the matching
		 ELF target vector.  */
	      goto next;
	    }
	  else if (type < GNU_PROPERTY_LOUSER
		   && bed->parse_gnu_properties)
	    {
	      enum elf_property_kind kind
		= bed->parse_gnu_properties (abfd, type, ptr, datasz);
	      if (kind == property_corrupt)
		{
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      else if (kind != property_ignored)
		goto next;
	    }
	}
      else
	{
	  switch (type)
	    {
	    case GNU_PROPERTY_STACK_SIZE:
	      if (datasz != align_size)
		{
		  _bfd_error_handler
		    (_("warning: %pB: corrupt stack size: 0x%x"),
		     abfd, datasz);
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      prop = _bfd_elf_get_property (abfd, type, datasz);
	      if (datasz == 8)
		prop->u.number = bfd_h_get_64 (abfd, ptr);
	      else
		prop->u.number = bfd_h_get_32 (abfd, ptr);
	      prop->pr_kind = property_number;
	      goto next;

	    case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
	      if (datasz != 0)
		{
		  _bfd_error_handler
		    (_("warning: %pB: corrupt no copy on protected size: 0x%x"),
		     abfd, datasz);
		  /* Clear all properties.  */
		  elf_properties (abfd) = NULL;
		  return FALSE;
		}
	      prop = _bfd_elf_get_property (abfd, type, datasz);
	      elf_has_no_copy_on_protected (abfd) = TRUE;
	      prop->pr_kind = property_number;
	      goto next;

	    default:
	      break;
	    }
	}

      _bfd_error_handler
	(_("warning: %pB: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x"),
	 abfd, note->type, type);

next:
      ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
    }

  return TRUE;
}

/* Merge GNU property BPROP with APROP.  If APROP isn't NULL, return TRUE
   if APROP is updated.  Otherwise, return TRUE if BPROP should be merged
   with ABFD.  */

static bfd_boolean
elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd,
			  elf_property *aprop, elf_property *bprop)
{
  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
  unsigned int pr_type = aprop != NULL ? aprop->pr_type : bprop->pr_type;

  if (bed->merge_gnu_properties != NULL
      && pr_type >= GNU_PROPERTY_LOPROC
      && pr_type < GNU_PROPERTY_LOUSER)
    return bed->merge_gnu_properties (info, abfd, aprop, bprop);

  switch (pr_type)
    {
    case GNU_PROPERTY_STACK_SIZE:
      if (aprop != NULL && bprop != NULL)
	{
	  if (bprop->u.number > aprop->u.number)
	    {
	      aprop->u.number = bprop->u.number;
	      return TRUE;
	    }
	  break;
	}
      /* FALLTHROUGH */

    case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
      /* Return TRUE if APROP is NULL to indicate that BPROP should
	 be added to ABFD.  */
      return aprop == NULL;

    default:
      /* Never should happen.  */
      abort ();
    }

  return FALSE;
}

/* Return the property of TYPE on *LISTP and remove it from *LISTP.
   Return NULL if not found.  */

static elf_property *
elf_find_and_remove_property (elf_property_list **listp,
			      unsigned int type)
{
  elf_property_list *list;

  for (list = *listp; list; list = list->next)
    {
      if (type == list->property.pr_type)
	{
	  /* Remove this property.  */
	  *listp = list->next;
	  return &list->property;
	}
      else if (type < list->property.pr_type)
	break;
      listp = &list->next;
    }

  return NULL;
}

/* Merge GNU property list *LISTP with ABFD.  */

static void
elf_merge_gnu_property_list (struct bfd_link_info *info, bfd *abfd,
			     elf_property_list **listp)
{
  elf_property_list *p, **lastp;
  elf_property *pr;

  /* Merge each GNU property in ABFD with the one on *LISTP.  */
  lastp = &elf_properties (abfd);
  for (p = *lastp; p; p = p->next)
    {
      pr = elf_find_and_remove_property (listp, p->property.pr_type);
      /* Pass NULL to elf_merge_gnu_properties for the property which
	 isn't on *LISTP.  */
      elf_merge_gnu_properties (info, abfd, &p->property, pr);
      if (p->property.pr_kind == property_remove)
	{
	  /* Remove this property.  */
	  *lastp = p->next;
	  continue;
	}
      lastp = &p->next;
    }

  /* Merge the remaining properties on *LISTP with ABFD.  */
  for (p = *listp; p != NULL; p = p->next)
    if (elf_merge_gnu_properties (info, abfd, NULL, &p->property))
      {
	if (p->property.pr_type == GNU_PROPERTY_NO_COPY_ON_PROTECTED)
	  elf_has_no_copy_on_protected (abfd) = TRUE;

	pr = _bfd_elf_get_property (abfd, p->property.pr_type,
				    p->property.pr_datasz);
	/* It must be a new property.  */
	if (pr->pr_kind != property_unknown)
	  abort ();
	/* Add a new property.  */
	*pr = p->property;
      }
}

/* Get GNU property section size.  */

static bfd_size_type
elf_get_gnu_property_section_size (elf_property_list *list,
				   unsigned int align_size)
{
  bfd_size_type size;
  unsigned int descsz;

  /* Compute the output section size.  */
  descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
  descsz = (descsz + 3) & -(unsigned int) 4;
  size = descsz;
  for (; list != NULL; list = list->next)
    {
      /* There are 4 byte type + 4 byte datasz for each property.  */
      unsigned int datasz;
      if (list->property.pr_type == GNU_PROPERTY_STACK_SIZE)
	datasz = align_size;
      else
	datasz = list->property.pr_datasz;
      size += 4 + 4 + datasz;
      /* Align each property.  */
      size = (size + (align_size - 1)) & ~(align_size - 1);
    }

  return size;
}

/* Write GNU properties.  */

static void
elf_write_gnu_properties (bfd *abfd, bfd_byte *contents,
			  elf_property_list *list, unsigned int size,
			  unsigned int align_size)
{
  unsigned int descsz;
  unsigned int datasz;
  Elf_External_Note *e_note;

  e_note = (Elf_External_Note *) contents;
  descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
  descsz = (descsz + 3) & -(unsigned int) 4;
  bfd_h_put_32 (abfd, sizeof "GNU", &e_note->namesz);
  bfd_h_put_32 (abfd, size - descsz, &e_note->descsz);
  bfd_h_put_32 (abfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
  memcpy (e_note->name, "GNU", sizeof "GNU");

  size = descsz;
  for (; list != NULL; list = list->next)
    {
      /* There are 4 byte type + 4 byte datasz for each property.  */
      if (list->property.pr_type == GNU_PROPERTY_STACK_SIZE)
	datasz = align_size;
      else
	datasz = list->property.pr_datasz;
      bfd_h_put_32 (abfd, list->property.pr_type, contents + size);
      bfd_h_put_32 (abfd, datasz, contents + size + 4);
      size += 4 + 4;

      /* Write out property value.  */
      switch (list->property.pr_kind)
	{
	case property_number:
	  switch (datasz)
	    {
	    default:
	      /* Never should happen.  */
	      abort ();

	    case 0:
	      break;

	    case 4:
	      bfd_h_put_32 (abfd, list->property.u.number,
			    contents + size);
	      break;

	    case 8:
	      bfd_h_put_64 (abfd, list->property.u.number,
			    contents + size);
	      break;
	    }
	  break;

	default:
	  /* Never should happen.  */
	  abort ();
	}
      size += datasz;

      /* Align each property.  */
      size = (size + (align_size - 1)) & ~ (align_size - 1);
    }
}

/* Set up GNU properties.  Return the first relocatable ELF input with
   GNU properties if found.  Otherwise, return NULL.  */

bfd *
_bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
{
  bfd *abfd, *first_pbfd = NULL;
  elf_property_list *list;
  asection *sec;
  bfd_boolean has_properties = FALSE;
  const struct elf_backend_data *bed
    = get_elf_backend_data (info->output_bfd);
  unsigned int elfclass = bed->s->elfclass;
  int elf_machine_code = bed->elf_machine_code;

  /* Find the first relocatable ELF input with GNU properties.  */
  for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
    if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
	&& (abfd->flags & DYNAMIC) == 0
	&& elf_properties (abfd) != NULL)
      {
	has_properties = TRUE;

	/* Ignore GNU properties from ELF objects with different machine
	   code or class.  Also skip objects without a GNU_PROPERTY note
	   section.  */
	if ((elf_machine_code
	     == get_elf_backend_data (abfd)->elf_machine_code)
	    && (elfclass
		== get_elf_backend_data (abfd)->s->elfclass)
	    && bfd_get_section_by_name (abfd,
					NOTE_GNU_PROPERTY_SECTION_NAME) != NULL
	    )
	  {
	    /* Keep .note.gnu.property section in FIRST_PBFD.  */
	    first_pbfd = abfd;
	    break;
	  }
      }

  /* Do nothing if there is no .note.gnu.property section.  */
  if (!has_properties)
    return NULL;

  /* Merge .note.gnu.property sections.  */
  for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
    if (abfd != first_pbfd
	&& (abfd->flags & (DYNAMIC | BFD_PLUGIN)) == 0)
      {
	elf_property_list *null_ptr = NULL;
	elf_property_list **listp = &null_ptr;

	/* Merge .note.gnu.property section in relocatable ELF input.  */
	if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
	  {
	    list = elf_properties (abfd);

	    /* Ignore GNU properties from ELF objects with different
	       machine code.  */
	    if (list != NULL
		&& (elf_machine_code
		    == get_elf_backend_data (abfd)->elf_machine_code))
	      listp = &elf_properties (abfd);
	  }
	else
	  list = NULL;

	/* Merge properties with FIRST_PBFD.  FIRST_PBFD can be NULL
	   when all properties are from ELF objects with different
	   machine code or class.  */
	if (first_pbfd != NULL)
	  elf_merge_gnu_property_list (info, first_pbfd, listp);

	if (list != NULL)
	  {
	    /* Discard the .note.gnu.property section in this bfd.  */
	    sec = bfd_get_section_by_name (abfd,
					   NOTE_GNU_PROPERTY_SECTION_NAME);
	    if (sec != NULL)
	      sec->output_section = bfd_abs_section_ptr;
	  }
      }

  /* Rewrite .note.gnu.property section so that GNU properties are
     always sorted by type even if input GNU properties aren't sorted.  */
  if (first_pbfd != NULL)
    {
      bfd_size_type size;
      bfd_byte *contents;
      unsigned int align_size = elfclass == ELFCLASS64 ? 8 : 4;

      sec = bfd_get_section_by_name (first_pbfd,
				     NOTE_GNU_PROPERTY_SECTION_NAME);
      BFD_ASSERT (sec != NULL);

      /* Update stack size in .note.gnu.property with -z stack-size=N
	 if N > 0.  */
      if (info->stacksize > 0)
	{
	  elf_property *p;
	  bfd_vma stacksize = info->stacksize;

	  p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
				     align_size);
	  if (p->pr_kind == property_unknown)
	    {
	      /* Create GNU_PROPERTY_STACK_SIZE.  */
	      p->u.number = stacksize;
	      p->pr_kind = property_number;
	    }
	  else if (stacksize > p->u.number)
	    p->u.number = stacksize;
	}
      else if (elf_properties (first_pbfd) == NULL)
	{
	  /* Discard .note.gnu.property section if all properties have
	     been removed.  */
	  sec->output_section = bfd_abs_section_ptr;
	  return NULL;
	}

      /* Fix up GNU properties.  */
      if (bed->fixup_gnu_properties)
	bed->fixup_gnu_properties (info, &elf_properties (first_pbfd));

      if (elf_properties (first_pbfd) == NULL)
	{
	  /* Discard .note.gnu.property section if all properties have
	     been removed.  */
	  sec->output_section = bfd_abs_section_ptr;
	  return NULL;
	}

      /* Compute the section size.  */
      list = elf_properties (first_pbfd);
      size = elf_get_gnu_property_section_size (list, align_size);

      /* Update .note.gnu.property section now.  */
      sec->size = size;
      contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);

      elf_write_gnu_properties (first_pbfd, contents, list, size,
				align_size);

      /* Cache the section contents for elf_link_input_bfd.  */
      elf_section_data (sec)->this_hdr.contents = contents;

      /* If GNU_PROPERTY_NO_COPY_ON_PROTECTED is set, protected data
	 symbol is defined in the shared object.  */
      if (elf_has_no_copy_on_protected (first_pbfd))
	info->extern_protected_data = FALSE;
    }

  return first_pbfd;
}

/* Convert GNU property size.  */

bfd_size_type
_bfd_elf_convert_gnu_property_size (bfd *ibfd, bfd *obfd)
{
  unsigned int align_size;
  const struct elf_backend_data *bed;
  elf_property_list *list = elf_properties (ibfd);

  bed = get_elf_backend_data (obfd);
  align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;

  /* Get the output .note.gnu.property section size.  */
  return elf_get_gnu_property_section_size (list, align_size);
}

/* Convert GNU properties.  */

bfd_boolean
_bfd_elf_convert_gnu_properties (bfd *ibfd, asection *isec,
				 bfd *obfd, bfd_byte **ptr,
				 bfd_size_type *ptr_size)
{
  unsigned int size;
  bfd_byte *contents;
  unsigned int align_shift;
  const struct elf_backend_data *bed;
  elf_property_list *list = elf_properties (ibfd);

  bed = get_elf_backend_data (obfd);
  align_shift = bed->s->elfclass == ELFCLASS64 ? 3 : 2;

  /* Get the output .note.gnu.property section size.  */
  size = bfd_get_section_size (isec->output_section);

  /* Update the output .note.gnu.property section alignment.  */
  bfd_set_section_alignment (obfd, isec->output_section, align_shift);

  if (size > bfd_get_section_size (isec))
    {
      contents = (bfd_byte *) bfd_malloc (size);
      free (*ptr);
      *ptr = contents;
    }
  else
    contents = *ptr;

  *ptr_size = size;

  /* Generate the output .note.gnu.property section.  */
  elf_write_gnu_properties (ibfd, contents, list, size, 1 << align_shift);

  return TRUE;
}