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 (struct bfd_link_info *info, bfd *abfd,
 201                           elf_property *aprop, 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 (info, 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 (struct bfd_link_info *info, bfd *abfd,
 267                              elf_property_list **listp)
 268 {
 269   elf_property_list *p, **lastp;
 270   elf_property *pr;
 271
 272   /* Merge each GNU property in ABFD with the one on *LISTP.  */
 273   lastp = &elf_properties (abfd);
 274   for (p = *lastp; p; p = p->next)
 275     {
 276       pr = elf_find_and_remove_property (listp, p->property.pr_type);
 277       /* Pass NULL to elf_merge_gnu_properties for the property which
 278          isn't on *LISTP.  */
 279       elf_merge_gnu_properties (info, abfd, &p->property, pr);
 280       if (p->property.pr_kind == property_remove)
 281         {
 282           /* Remove this property.  */
 283           *lastp = p->next;
 284           continue;
 285         }
 286       lastp = &p->next;
 287     }
 288
 289   /* Merge the remaining properties on *LISTP with ABFD.  */
 290   for (p = *listp; p != NULL; p = p->next)
 291     if (elf_merge_gnu_properties (info, abfd, NULL, &p->property))
 292       {
 293         pr = _bfd_elf_get_property (abfd, p->property.pr_type,
 294                                     p->property.pr_datasz);
 295         /* It must be a new property.  */
 296         if (pr->pr_kind != property_unknown)
 297           abort ();
 298         /* Add a new property.  */
 299         *pr = p->property;
 300       }
 301 }
 302
 303 /* Set up GNU properties.  Return the first relocatable ELF input with
 304    GNU properties if found.  Otherwise, return NULL.  */
 305
 306 bfd *
 307 _bfd_elf_link_setup_gnu_properties (struct bfd_link_info *info)
 308 {
 309   bfd *abfd, *first_pbfd = NULL;
 310   elf_property_list *list;
 311   asection *sec;
 312   bfd_boolean has_properties = FALSE;
 313   const struct elf_backend_data *bed
 314     = get_elf_backend_data (info->output_bfd);
 315   unsigned int elfclass = bed->s->elfclass;
 316   int elf_machine_code = bed->elf_machine_code;
 317
 318   /* Find the first relocatable ELF input with GNU properties.  */
 319   for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
 320     if (bfd_get_flavour (abfd) == bfd_target_elf_flavour
 321         && (abfd->flags & DYNAMIC) == 0
 322         && elf_properties (abfd) != NULL)
 323       {
 324         has_properties = TRUE;
 325
 326         /* Ignore GNU properties from ELF objects with different machine
 327            code or class.  */
 328         if ((elf_machine_code
 329              == get_elf_backend_data (abfd)->elf_machine_code)
 330             && (elfclass
 331                 == get_elf_backend_data (abfd)->s->elfclass))
 332           {
 333             /* Keep .note.gnu.property section in FIRST_PBFD.  */
 334             first_pbfd = abfd;
 335             break;
 336           }
 337       }
 338
 339   /* Do nothing if there is no .note.gnu.property section.  */
 340   if (!has_properties)
 341     return NULL;
 342
 343   /* Merge .note.gnu.property sections.  */
 344   for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
 345     if (abfd != first_pbfd && (abfd->flags & DYNAMIC) == 0)
 346       {
 347         elf_property_list *null_ptr = NULL;
 348         elf_property_list **listp = &null_ptr;
 349
 350         /* Merge .note.gnu.property section in relocatable ELF input.  */
 351         if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
 352           {
 353             list = elf_properties (abfd);
 354
 355             /* Ignore GNU properties from ELF objects with different
 356                machine code.  */
 357             if (list != NULL
 358                 && (elf_machine_code
 359                     == get_elf_backend_data (abfd)->elf_machine_code))
 360               listp = &elf_properties (abfd);
 361           }
 362         else
 363           list = NULL;
 364
 365         /* Merge properties with FIRST_PBFD.  FIRST_PBFD can be NULL
 366            when all properties are from ELF objects with different
 367            machine code or class.  */
 368         if (first_pbfd != NULL)
 369           elf_merge_gnu_property_list (info, first_pbfd, listp);
 370
 371         if (list != NULL)
 372           {
 373             /* Discard .note.gnu.property section in the rest inputs.  */
 374             sec = bfd_get_section_by_name (abfd,
 375                                            NOTE_GNU_PROPERTY_SECTION_NAME);
 376             sec->output_section = bfd_abs_section_ptr;
 377           }
 378       }
 379
 380   /* Rewrite .note.gnu.property section so that GNU properties are
 381      always sorted by type even if input GNU properties aren't sorted.  */
 382   if (first_pbfd != NULL)
 383     {
 384       unsigned int size;
 385       unsigned int descsz;
 386       bfd_byte *contents;
 387       Elf_External_Note *e_note;
 388       unsigned int align_size = bed->s->elfclass == ELFCLASS64 ? 8 : 4;
 389
 390       sec = bfd_get_section_by_name (first_pbfd,
 391                                      NOTE_GNU_PROPERTY_SECTION_NAME);
 392
 393       /* Update stack size in .note.gnu.property with -z stack-size=N
 394          if N > 0.  */
 395       if (info->stacksize > 0)
 396         {
 397           elf_property *p;
 398           bfd_vma stacksize = info->stacksize;
 399
 400           p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_STACK_SIZE,
 401                                      align_size);
 402           if (p->pr_kind == property_unknown)
 403             {
 404               /* Create GNU_PROPERTY_STACK_SIZE.  */
 405               p->u.number = stacksize;
 406               p->pr_kind = property_number;
 407             }
 408           else if (stacksize > p->u.number)
 409             p->u.number = stacksize;
 410         }
 411       else if (elf_properties (first_pbfd) == NULL)
 412         {
 413           /* Discard .note.gnu.property section if all properties have
 414              been removed.  */
 415           sec->output_section = bfd_abs_section_ptr;
 416           return NULL;
 417         }
 418
 419       /* Compute the section size.  */
 420       descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
 421       descsz = (descsz + 3) & -(unsigned int) 4;
 422       size = descsz;
 423       for (list = elf_properties (first_pbfd);
 424            list != NULL;
 425            list = list->next)
 426         {
 427           /* There are 4 byte type + 4 byte datasz for each property.  */
 428           size += 4 + 4 + list->property.pr_datasz;
 429           /* Align each property.  */
 430           size = (size + (align_size - 1)) & ~(align_size - 1);
 431         }
 432
 433       /* Update .note.gnu.property section now.  */
 434       sec->size = size;
 435       contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);
 436
 437       e_note = (Elf_External_Note *) contents;
 438       bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
 439       bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
 440       bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
 441       memcpy (e_note->name, "GNU", sizeof "GNU");
 442
 443       size = descsz;
 444       for (list = elf_properties (first_pbfd);
 445            list != NULL;
 446            list = list->next)
 447         {
 448           /* There are 4 byte type + 4 byte datasz for each property.  */
 449           bfd_h_put_32 (first_pbfd, list->property.pr_type,
 450                         contents + size);
 451           bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
 452                         contents + size + 4);
 453           size += 4 + 4;
 454
 455           /* Write out property value.  */
 456           switch (list->property.pr_kind)
 457             {
 458             case property_number:
 459               switch (list->property.pr_datasz)
 460                 {
 461                 default:
 462                   /* Never should happen.  */
 463                   abort ();
 464
 465                 case 0:
 466                   break;
 467
 468                 case 4:
 469                   bfd_h_put_32 (first_pbfd, list->property.u.number,
 470                                 contents + size);
 471                   break;
 472
 473                 case 8:
 474                   bfd_h_put_64 (first_pbfd, list->property.u.number,
 475                                 contents + size);
 476                   break;
 477                 }
 478               break;
 479
 480             default:
 481               /* Never should happen.  */
 482               abort ();
 483             }
 484           size += list->property.pr_datasz;
 485
 486           /* Align each property.  */
 487           size = (size + (align_size - 1)) & ~ (align_size - 1);
 488         }
 489
 490       /* Cache the section contents for elf_link_input_bfd.  */
 491       elf_section_data (sec)->this_hdr.contents = contents;
 492     }
 493
 494   return first_pbfd;
 495 }