bfd/elf-properties.c

   1 /* ELF program property support.
   2    Copyright (C) 2017 Free Software Foundation, Inc.
   3
   4    This file is part of BFD, the Binary File Descriptor library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  19    MA 02110-1301, USA.  */
  20
  21 /* GNU program property draft is at:
  22
  23    https://github.com/hjl-tools/linux-abi/wiki/property-draft.pdf
  24  */
  25
  26 #include "sysdep.h"
  27 #include "bfd.h"
  28 #include "libbfd.h"
  29 #include "elf-bfd.h"
  30
  31 /* Get a property, allocate a new one if needed.  */
  32
  33 elf_property *
  34 _bfd_elf_get_property (bfd *abfd, unsigned int type, unsigned int datasz)
  35 {
  36   elf_property_list *p, **lastp;
  37
  38   if (bfd_get_flavour (abfd) != bfd_target_elf_flavour)
  39     {
  40       /* Never should happen.  */
  41       abort ();
  42     }
  43
  44   /* Keep the property list in order of type.  */
  45   lastp = &elf_properties (abfd);
  46   for (p = *lastp; p; p = p->next)
  47     {
  48       /* Reuse the existing entry.  */
  49       if (type == p->property.pr_type)
  50         {
  51           if (datasz > p->property.pr_datasz)
  52             {
  53               /* This can happen when mixing 32-bit and 64-bit objects.  */
  54               p->property.pr_datasz = datasz;
  55             }
  56           return &p->property;
  57         }
  58       else if (type < p->property.pr_type)
  59         break;
  60       lastp = &p->next;
  61     }
  62   p = (elf_property_list *) bfd_alloc (abfd, sizeof (*p));
  63   if (p == NULL)
  64     {
  65       _bfd_error_handler (_("%B: out of memory in _bfd_elf_get_property"),
  66                           abfd);
  67       _exit (EXIT_FAILURE);
  68     }
  69   memset (p, 0, sizeof (*p));
  70   p->property.pr_type = type;
  71   p->property.pr_datasz = datasz;
  72   p->next = *lastp;
  73   *lastp = p;
  74   return &p->property;
  75 }
  76
  77 /* Parse GNU properties.  */
  78
  79 bfd_boolean
  80 _bfd_elf_parse_gnu_properties (bfd *abfd, Elf_Internal_Note *note)
  81 {
  82   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
  83   unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
  84   bfd_byte *ptr = (bfd_byte *) note->descdata;
  85   bfd_byte *ptr_end = ptr + note->descsz;
  86
  87   if (note->descsz < 8 || (note->descsz % align_size) != 0)
  88     {
  89 bad_size:
  90       _bfd_error_handler
  91         (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) size: %#lx"),
  92          abfd, note->type, note->descsz);
  93       return FALSE;
  94     }
  95
  96   while (1)
  97     {
  98       unsigned int type = bfd_h_get_32 (abfd, ptr);
  99       unsigned int datasz = bfd_h_get_32 (abfd, ptr + 4);
 100       elf_property *prop;
 101
 102       ptr += 8;
 103
 104       if ((ptr + datasz) > ptr_end)
 105         {
 106           _bfd_error_handler
 107             (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x"),
 108              abfd, note->type, type, datasz);
 109           /* Clear all properties.  */
 110           elf_properties (abfd) = NULL;
 111           return FALSE;
 112         }
 113
 114       if (type >= GNU_PROPERTY_LOPROC)
 115         {
 116           if (bed->elf_machine_code == EM_NONE)
 117             {
 118               /* Ignore processor-specific properties with generic ELF
 119                  target vector.  They should be handled by the matching
 120                  ELF target vector.  */
 121               goto next;
 122             }
 123           else if (type < GNU_PROPERTY_LOUSER
 124                    && bed->parse_gnu_properties)
 125             {
 126               enum elf_property_kind kind
 127                 = bed->parse_gnu_properties (abfd, type, ptr, datasz);
 128               if (kind == property_corrupt)
 129                 {
 130                   /* Clear all properties.  */
 131                   elf_properties (abfd) = NULL;
 132                   return FALSE;
 133                 }
 134               else if (kind != property_ignored)
 135                 goto next;
 136             }
 137         }
 138       else
 139         {
 140           switch (type)
 141             {
 142             case GNU_PROPERTY_STACK_SIZE:
 143               if (datasz != align_size)
 144                 {
 145                   _bfd_error_handler
 146                     (_("warning: %B: corrupt stack size: 0x%x"),
 147                      abfd, datasz);
 148                   /* Clear all properties.  */
 149                   elf_properties (abfd) = NULL;
 150                   return FALSE;
 151                 }
 152               prop = _bfd_elf_get_property (abfd, type, datasz);
 153               if (datasz == 8)
 154                 prop->u.number = bfd_h_get_64 (abfd, ptr);
 155               else
 156                 prop->u.number = bfd_h_get_32 (abfd, ptr);
 157               prop->pr_kind = property_number;
 158               goto next;
 159
 160             case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
 161               if (datasz != 0)
 162                 {
 163                   _bfd_error_handler
 164                     (_("warning: %B: corrupt no copy on protected size: 0x%x"),
 165                      abfd, datasz);
 166                   /* Clear all properties.  */
 167                   elf_properties (abfd) = NULL;
 168                   return FALSE;
 169                 }
 170               prop = _bfd_elf_get_property (abfd, type, datasz);
 171               prop->pr_kind = property_number;
 172               goto next;
 173
 174             default:
 175               break;
 176             }
 177         }
 178
 179       _bfd_error_handler
 180         (_("warning: %B: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x"),
 181          abfd, note->type, type);
 182
 183 next:
 184       ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
 185       if (ptr == ptr_end)
 186         break;
 187
 188       if (ptr > (ptr_end - 8))
 189         goto bad_size;
 190     }
 191
 192   return TRUE;
 193 }
 194
 195 /* Merge GNU property BPROP with APROP.  If APROP isn't NULL, return TRUE
 196    if APROP is updated.  Otherwise, return TRUE if BPROP should be merged
 197    with ABFD.  */
 198
 199 static bfd_boolean
 200 elf_merge_gnu_properties (bfd *abfd, elf_property *aprop,
 201                           elf_property *bprop)
 202 {
 203   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
 204   unsigned int pr_type = aprop != NULL ? aprop->pr_type : bprop->pr_type;
 205
 206   if (bed->merge_gnu_properties != NULL
 207       && pr_type >= GNU_PROPERTY_LOPROC
 208       && pr_type < GNU_PROPERTY_LOUSER)
 209     return bed->merge_gnu_properties (abfd, aprop, bprop);
 210
 211   switch (pr_type)
 212     {
 213     case GNU_PROPERTY_STACK_SIZE:
 214       if (aprop != NULL && bprop != NULL)
 215         {
 216           if (bprop->u.number > aprop->u.number)
 217             {
 218               aprop->u.number = bprop->u.number;
 219               return TRUE;
 220             }
 221           break;
 222         }
 223       /* FALLTHROUGH */
 224
 225     case GNU_PROPERTY_NO_COPY_ON_PROTECTED:
 226       /* Return TRUE if APROP is NULL to indicate that BPROP should
 227          be added to ABFD.  */
 228       return aprop == NULL;
 229
 230     default:
 231       /* Never should happen.  */
 232       abort ();
 233     }
 234
 235   return FALSE;
 236 }
 237
 238 /* Return the property of TYPE on *LISTP and remove it from *LISTP.
 239    Return NULL if not found.  */
 240
 241 static elf_property *
 242 elf_find_and_remove_property (elf_property_list **listp,
 243                               unsigned int type)
 244 {
 245   elf_property_list *list;
 246
 247   for (list = *listp; list; list = list->next)
 248     {
 249       if (type == list->property.pr_type)
 250         {
 251           /* Remove this property.  */
 252           *listp = list->next;
 253           return &list->property;
 254         }
 255       else if (type < list->property.pr_type)
 256         break;
 257       listp = &list->next;
 258     }
 259
 260   return NULL;
 261 }
 262
 263 /* Merge GNU property list *LISTP with ABFD.  */
 264
 265 static void
 266 elf_merge_gnu_property_list (bfd *abfd, elf_property_list **listp)
 267 {
 268   elf_property_list *p, **lastp;
 269   elf_property *pr;
 270
 271   /* Merge each GNU property in ABFD with the one on *LISTP.  */
 272   lastp = &elf_properties (abfd);
 273   for (p = *lastp; p; p = p->next)
 274     {
 275       pr = elf_find_and_remove_property (listp, p->property.pr_type);
 276       /* Pass NULL to elf_merge_gnu_properties for the property which
 277          isn't on *LISTP.  */
 278       elf_merge_gnu_properties (abfd, &p->property, pr);
 279       if (p->property.pr_kind == property_remove)
 280         {
 281           /* Remove this property.  */
 282           *lastp = p->next;
 283           continue;
 284         }
 285       lastp = &p->next;
 286     }
 287
 288   /* Merge the remaining properties on *LISTP with ABFD.  */
 289   for (p = *listp; p != NULL; p = p->next)
 290     if (elf_merge_gnu_properties (abfd, NULL, &p->property))
 291       {
 292         pr = _bfd_elf_get_property (abfd, p->property.pr_type,
 293                                     p->property.pr_datasz);
 294         /* It must be a new property.  */
 295         if (pr->pr_kind != property_unknown)
 296           abort ();
 297         /* Add a new property.  */
 298         *pr = p->property;
 299       }
 300 }
 301
 302 /* Set up GNU properties.  Return the first relocatable ELF input with
 303    GNU properties if found.  Otherwise, return NULL.  */
 304
 305 bfd *
 306 _bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
 307 {
 308   bfd *abfd, *first_pbfd = NULL;
 309   elf_property_list *list;
 310   asection *sec;
 311   bfd_boolean has_properties = FALSE;
 312   const struct elf_backend_data *bed
 313     = get_elf_backend_data (info->output_bfd);
 314   unsigned int elfclass = bed->s->elfclass;
 315   int elf_machine_code = bed->elf_machine_code;
 316
 317   /* Find the first relocatable ELF input with GNU properties.  */
 318   for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
 319     if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
 320         && bfd_count_sections (abfd) != 0
 321         && elf_properties (abfd) != NULL)
 322       {
 323         has_properties = TRUE;
 324
 325         /* Ignore GNU properties from ELF objects with different machine
 326            code or class.  */
 327         if ((elf_machine_code
 328              == get_elf_backend_data (abfd)->elf_machine_code)
 329             && (elfclass
 330                 == get_elf_backend_data (abfd)->s->elfclass))
 331           {
 332             /* Keep .note.gnu.property section in FIRST_PBFD.  */
 333             first_pbfd = abfd;
 334             break;
 335           }
 336       }
 337
 338   /* Do nothing if there is no .note.gnu.property section.  */
 339   if (!has_properties)
 340     return NULL;
 341
 342   /* Merge .note.gnu.property sections.  */
 343   for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
 344     if (abfd != first_pbfd && bfd_count_sections (abfd) != 0)
 345       {
 346         elf_property_list *null_ptr = NULL;
 347         elf_property_list **listp = &null_ptr;
 348
 349         /* Merge .note.gnu.property section in relocatable ELF input.  */
 350         if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
 351           {
 352             list = elf_properties (abfd);
 353
 354             /* Ignore GNU properties from ELF objects with different
 355                machine code.  */
 356             if (list != NULL
 357                 && (elf_machine_code
 358                     == get_elf_backend_data (abfd)->elf_machine_code))
 359               listp = &elf_properties (abfd);
 360           }
 361         else
 362           list = NULL;
 363
 364         /* Merge properties with FIRST_PBFD.  FIRST_PBFD can be NULL
 365            when all properties are from ELF objects with different
 366            machine code or class.  */
 367         if (first_pbfd != NULL)
 368           elf_merge_gnu_property_list (first_pbfd, listp);
 369
 370         if (list != NULL)
 371           {
 372             /* Discard .note.gnu.property section in the rest inputs.  */
 373             sec = bfd_get_section_by_name (abfd,
 374                                            NOTE_GNU_PROPERTY_SECTION_NAME);
 375             sec->output_section = bfd_abs_section_ptr;
 376           }
 377       }
 378
 379   /* Rewrite .note.gnu.property section so that GNU properties are
 380      always sorted by type even if input GNU properties aren't sorted.  */
 381   if (first_pbfd != NULL)
 382     {
 383       unsigned int size;
 384       unsigned int descsz;
 385       bfd_byte *contents;
 386       Elf_External_Note *e_note;
 387       unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
 388
 389       sec = bfd_get_section_by_name (first_pbfd,
 390                                      NOTE_GNU_PROPERTY_SECTION_NAME);
 391
 392       /* Update stack size in .note.gnu.property with -z stack-size=N
 393          if N > 0.  */
 394       if (info->stacksize > 0)
 395         {
 396           elf_property *p;
 397           bfd_vma stacksize = info->stacksize;
 398
 399           p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
 400                                      align_size);
 401           if (p->pr_kind == property_unknown)
 402             {
 403               /* Create GNU_PROPERTY_STACK_SIZE.  */
 404               p->u.number = stacksize;
 405               p->pr_kind = property_number;
 406             }
 407           else if (stacksize > p->u.number)
 408             p->u.number = stacksize;
 409         }
 410       else if (elf_properties (first_pbfd) == NULL)
 411         {
 412           /* Discard .note.gnu.property section if all properties have
 413              been removed.  */
 414           sec->output_section = bfd_abs_section_ptr;
 415           return NULL;
 416         }
 417
 418       /* Compute the section size.  */
 419       descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
 420       descsz = (descsz + 3) & -(unsigned int) 4;
 421       size = descsz;
 422       for (list = elf_properties (first_pbfd);
 423            list != NULL;
 424            list = list->next)
 425         {
 426           /* There are 4 byte type + 4 byte datasz for each property.  */
 427           size += 4 + 4 + list->property.pr_datasz;
 428           /* Align each property.  */
 429           size = (size + (align_size - 1)) & ~(align_size - 1);
 430         }
 431
 432       /* Update .note.gnu.property section now.  */
 433       sec->size = size;
 434       contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);
 435
 436       e_note = (Elf_External_Note *) contents;
 437       bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
 438       bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
 439       bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
 440       memcpy (e_note->name, "GNU", sizeof "GNU");
 441
 442       size = descsz;
 443       for (list = elf_properties (first_pbfd);
 444            list != NULL;
 445            list = list->next)
 446         {
 447           /* There are 4 byte type + 4 byte datasz for each property.  */
 448           bfd_h_put_32 (first_pbfd, list->property.pr_type,
 449                         contents + size);
 450           bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
 451                         contents + size + 4);
 452           size += 4 + 4;
 453
 454           /* Write out property value.  */
 455           switch (list->property.pr_kind)
 456             {
 457             case property_number:
 458               switch (list->property.pr_datasz)
 459                 {
 460                 default:
 461                   /* Never should happen.  */
 462                   abort ();
 463
 464                 case 0:
 465                   break;
 466
 467                 case 4:
 468                   bfd_h_put_32 (first_pbfd, list->property.u.number,
 469                                 contents + size);
 470                   break;
 471
 472                 case 8:
 473                   bfd_h_put_64 (first_pbfd, list->property.u.number,
 474                                 contents + size);
 475                   break;
 476                 }
 477               break;
 478
 479             default:
 480               /* Never should happen.  */
 481               abort ();
 482             }
 483           size += list->property.pr_datasz;
 484
 485           /* Align each property.  */
 486           size = (size + (align_size - 1)) & ~ (align_size - 1);
 487         }
 488
 489       /* Cache the section contents for elf_link_input_bfd.  */
 490       elf_section_data (sec)->this_hdr.contents = contents;
 491     }
 492
 493   return first_pbfd;
 494 }