/* ELF program property support. Copyright (C) 2017-2023 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. */ bool _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: if ((type >= GNU_PROPERTY_UINT32_AND_LO && type <= GNU_PROPERTY_UINT32_AND_HI) || (type >= GNU_PROPERTY_UINT32_OR_LO && type <= GNU_PROPERTY_UINT32_OR_HI)) { if (datasz != 4) { _bfd_error_handler (_("error: %pB: "), abfd, type, datasz); /* Clear all properties. */ elf_properties (abfd) = NULL; return false; } prop = _bfd_elf_get_property (abfd, type, datasz); prop->u.number |= bfd_h_get_32 (abfd, ptr); prop->pr_kind = property_number; if (type == GNU_PROPERTY_1_NEEDED && ((prop->u.number & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS) != 0)) { elf_has_indirect_extern_access (abfd) = true; /* GNU_PROPERTY_NO_COPY_ON_PROTECTED is implied. */ elf_has_no_copy_on_protected (abfd) = true; } goto next; } 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 bool elf_merge_gnu_properties (struct bfd_link_info *info, bfd *abfd, bfd *bbfd, 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; unsigned int number; bool updated; if (bed->merge_gnu_properties != NULL && pr_type >= GNU_PROPERTY_LOPROC && pr_type < GNU_PROPERTY_LOUSER) return bed->merge_gnu_properties (info, abfd, bbfd, 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: updated = false; if (pr_type >= GNU_PROPERTY_UINT32_OR_LO && pr_type <= GNU_PROPERTY_UINT32_OR_HI) { if (aprop != NULL && bprop != NULL) { number = aprop->u.number; aprop->u.number = number | bprop->u.number; /* Remove the property if all bits are empty. */ if (aprop->u.number == 0) { aprop->pr_kind = property_remove; updated = true; } else updated = number != (unsigned int) aprop->u.number; } else { /* Only one of APROP and BPROP can be NULL. */ if (aprop != NULL) { if (aprop->u.number == 0) { /* Remove APROP if all bits are empty. */ aprop->pr_kind = property_remove; updated = true; } } else { /* Return TRUE if APROP is NULL and all bits of BPROP aren't empty to indicate that BPROP should be added to ABFD. */ updated = bprop->u.number != 0; } } return updated; } else if (pr_type >= GNU_PROPERTY_UINT32_AND_LO && pr_type <= GNU_PROPERTY_UINT32_AND_HI) { /* Only one of APROP and BPROP can be NULL: 1. APROP & BPROP when both APROP and BPROP aren't NULL. 2. If APROP is NULL, remove x86 feature. 3. Otherwise, do nothing. */ if (aprop != NULL && bprop != NULL) { number = aprop->u.number; aprop->u.number = number & bprop->u.number; updated = number != (unsigned int) aprop->u.number; /* Remove the property if all feature bits are cleared. */ if (aprop->u.number == 0) aprop->pr_kind = property_remove; } else { /* There should be no AND properties since some input doesn't have them. */ if (aprop != NULL) { aprop->pr_kind = property_remove; updated = true; } } return updated; } /* Never should happen. */ abort (); } return false; } /* Return the property of TYPE on *LISTP and remove it from *LISTP if RM is true. Return NULL if not found. */ static elf_property * elf_find_and_remove_property (elf_property_list **listp, unsigned int type, bool rm) { elf_property_list *list; for (list = *listp; list; list = list->next) { if (type == list->property.pr_type) { /* Remove this property. */ if (rm) *listp = list->next; return &list->property; } else if (type < list->property.pr_type) break; listp = &list->next; } return NULL; } /* Merge GNU property list *LISTP in ABFD with FIRST_PBFD. */ static void elf_merge_gnu_property_list (struct bfd_link_info *info, bfd *first_pbfd, bfd *abfd, elf_property_list **listp) { elf_property_list *p, **lastp; elf_property *pr; bool number_p; bfd_vma number = 0; /* Merge each GNU property in FIRST_PBFD with the one on *LISTP. */ lastp = &elf_properties (first_pbfd); for (p = *lastp; p; p = p->next) if (p->property.pr_kind != property_remove) { if (p->property.pr_kind == property_number) { number_p = true; number = p->property.u.number; } else number_p = false; pr = elf_find_and_remove_property (listp, p->property.pr_type, true); /* Pass NULL to elf_merge_gnu_properties for the property which isn't on *LISTP. */ elf_merge_gnu_properties (info, first_pbfd, abfd, &p->property, pr); if (p->property.pr_kind == property_remove) { if (info->has_map_file) { if (number_p) { if (pr != NULL) info->callbacks->minfo (_("Removed property %W to merge %pB (0x%v) " "and %pB (0x%v)\n"), (bfd_vma) p->property.pr_type, first_pbfd, number, abfd, pr->u.number); else info->callbacks->minfo (_("Removed property %W to merge %pB (0x%v) " "and %pB (not found)\n"), (bfd_vma) p->property.pr_type, first_pbfd, number, abfd); } else { if (pr != NULL) info->callbacks->minfo (_("Removed property %W to merge %pB and %pB\n"), (bfd_vma) p->property.pr_type, first_pbfd, abfd); else info->callbacks->minfo (_("Removed property %W to merge %pB and %pB " "(not found)\n"), (bfd_vma) p->property.pr_type, first_pbfd, abfd); } } /* Remove this property. */ *lastp = p->next; continue; } else if (number_p) { if (pr != NULL) { if (p->property.u.number != number || p->property.u.number != pr->u.number) info->callbacks->minfo (_("Updated property %W (0x%v) to merge %pB (0x%v) " "and %pB (0x%v)\n"), (bfd_vma) p->property.pr_type, p->property.u.number, first_pbfd, number, abfd, pr->u.number); } else { if (p->property.u.number != number) info->callbacks->minfo (_("Updated property %W (%v) to merge %pB (0x%v) " "and %pB (not found)\n"), (bfd_vma) p->property.pr_type, p->property.u.number, first_pbfd, number, abfd); } } lastp = &p->next; } /* Merge the remaining properties on *LISTP with FIRST_PBFD. */ for (p = *listp; p != NULL; p = p->next) { if (p->property.pr_kind == property_number) { number_p = true; number = p->property.u.number; } else number_p = false; if (elf_merge_gnu_properties (info, first_pbfd, abfd, NULL, &p->property)) { if (p->property.pr_type == GNU_PROPERTY_NO_COPY_ON_PROTECTED) elf_has_no_copy_on_protected (first_pbfd) = true; pr = _bfd_elf_get_property (first_pbfd, 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; } else { pr = elf_find_and_remove_property (&elf_properties (first_pbfd), p->property.pr_type, false); if (pr == NULL) { if (number_p) info->callbacks->minfo (_("Removed property %W to merge %pB (not found) and " "%pB (0x%v)\n"), (bfd_vma) p->property.pr_type, first_pbfd, abfd, number); else info->callbacks->minfo (_("Removed property %W to merge %pB and %pB\n"), (bfd_vma) p->property.pr_type, first_pbfd, abfd); } else if (pr->pr_kind != property_remove) abort (); } } } /* 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) { unsigned int datasz; /* Check if this property should be skipped. */ if (list->property.pr_kind == property_remove) continue; /* 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; 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 (struct bfd_link_info *info, 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) { /* Check if this property should be skipped. */ if (list->property.pr_kind == property_remove) continue; /* 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: /* Save the pointer to GNU_PROPERTY_1_NEEDED so that it can be updated later if needed. */ if (info != NULL && list->property.pr_type == GNU_PROPERTY_1_NEEDED) info->needed_1_p = contents + size; 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_bfd = NULL; elf_property_list *list; asection *sec; bool 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; elf_property *p; /* 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_machine_code == get_elf_backend_data (abfd)->elf_machine_code) && (elfclass == get_elf_backend_data (abfd)->s->elfclass)) { /* Ignore GNU properties from ELF objects with different machine code or class. Also skip objects without a GNU_PROPERTY note section. */ elf_bfd = abfd; if (elf_properties (abfd) != NULL) { has_properties = true; if (bfd_get_section_by_name (abfd, NOTE_GNU_PROPERTY_SECTION_NAME) != NULL) { /* Keep .note.gnu.property section in FIRST_PBFD. */ first_pbfd = abfd; break; } } } if (info->indirect_extern_access > 0 && elf_bfd != NULL) { /* Support -z indirect-extern-access. */ if (first_pbfd == NULL) { sec = bfd_make_section_with_flags (elf_bfd, NOTE_GNU_PROPERTY_SECTION_NAME, (SEC_ALLOC | SEC_LOAD | SEC_IN_MEMORY | SEC_READONLY | SEC_HAS_CONTENTS | SEC_DATA)); if (sec == NULL) info->callbacks->einfo (_("%F%P: failed to create GNU property section\n")); if (!bfd_set_section_alignment (sec, elfclass == ELFCLASS64 ? 3 : 2)) info->callbacks->einfo (_("%F%pA: failed to align section\n"), sec); elf_section_type (sec) = SHT_NOTE; first_pbfd = elf_bfd; has_properties = true; } p = _bfd_elf_get_property (first_pbfd, GNU_PROPERTY_1_NEEDED, 4); if (p->pr_kind == property_unknown) { /* Create GNU_PROPERTY_1_NEEDED. */ p->u.number = GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS; p->pr_kind = property_number; } else p->u.number |= GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS; } /* Do nothing if there is no .note.gnu.property section. */ if (!has_properties) return NULL; /* Merge .note.gnu.property sections. */ info->callbacks->minfo (_("\n")); info->callbacks->minfo (_("Merging program properties\n")); info->callbacks->minfo (_("\n")); for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next) if (abfd != first_pbfd && (abfd->flags & (DYNAMIC | BFD_PLUGIN | BFD_LINKER_CREATED)) == 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, abfd, 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) { 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); if (info->indirect_extern_access <= 0) { /* Get GNU_PROPERTY_1_NEEDED properties. */ p = elf_find_and_remove_property (&elf_properties (first_pbfd), GNU_PROPERTY_1_NEEDED, false); if (p != NULL) { if (info->indirect_extern_access < 0) { /* Set indirect_extern_access to 1 to indicate that it is turned on by input properties. */ if ((p->u.number & GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS) != 0) info->indirect_extern_access = 1; } else /* Turn off indirect external access. */ p->u.number &= ~GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS; } } elf_write_gnu_properties (info, 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; if (info->indirect_extern_access > 0) { /* For indirect external access, don't generate copy relocations. NB: Set to nocopyreloc to 2 to indicate that it is implied by indirect_extern_access. */ info->nocopyreloc = 2; 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. */ bool _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_section_size (isec->output_section); /* Update the output .note.gnu.property section alignment. */ bfd_set_section_alignment (isec->output_section, align_shift); if (size > bfd_section_size (isec)) { contents = (bfd_byte *) bfd_malloc (size); if (contents == NULL) return false; free (*ptr); *ptr = contents; } else contents = *ptr; *ptr_size = size; /* Generate the output .note.gnu.property section. */ elf_write_gnu_properties (NULL, ibfd, contents, list, size, 1 << align_shift); return true; }