binutils-gdb/bfd/elf-properties.c

511 lines
14 KiB
C

/* 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 (_("%B: 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: %B: 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: %B: 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: %B: 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: %B: 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: %B: 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;
}
}
/* 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) == 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)
{
unsigned int size;
unsigned int descsz;
bfd_byte *contents;
Elf_External_Note *e_note;
unsigned int align_size = bed->s->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;
}
/* Compute the section size. */
descsz = offsetof (Elf_External_Note, name[sizeof "GNU"]);
descsz = (descsz + 3) & -(unsigned int) 4;
size = descsz;
for (list = elf_properties (first_pbfd);
list != NULL;
list = list->next)
{
/* There are 4 byte type + 4 byte datasz for each property. */
size += 4 + 4 + list->property.pr_datasz;
/* Align each property. */
size = (size + (align_size - 1)) & ~(align_size - 1);
}
/* Update .note.gnu.property section now. */
sec->size = size;
contents = (bfd_byte *) bfd_zalloc (first_pbfd, size);
e_note = (Elf_External_Note *) contents;
bfd_h_put_32 (first_pbfd, sizeof "GNU", &e_note->namesz);
bfd_h_put_32 (first_pbfd, size - descsz, &e_note->descsz);
bfd_h_put_32 (first_pbfd, NT_GNU_PROPERTY_TYPE_0, &e_note->type);
memcpy (e_note->name, "GNU", sizeof "GNU");
size = descsz;
for (list = elf_properties (first_pbfd);
list != NULL;
list = list->next)
{
/* There are 4 byte type + 4 byte datasz for each property. */
bfd_h_put_32 (first_pbfd, list->property.pr_type,
contents + size);
bfd_h_put_32 (first_pbfd, list->property.pr_datasz,
contents + size + 4);
size += 4 + 4;
/* Write out property value. */
switch (list->property.pr_kind)
{
case property_number:
switch (list->property.pr_datasz)
{
default:
/* Never should happen. */
abort ();
case 0:
break;
case 4:
bfd_h_put_32 (first_pbfd, list->property.u.number,
contents + size);
break;
case 8:
bfd_h_put_64 (first_pbfd, list->property.u.number,
contents + size);
break;
}
break;
default:
/* Never should happen. */
abort ();
}
size += list->property.pr_datasz;
/* Align each property. */
size = (size + (align_size - 1)) & ~ (align_size - 1);
}
/* 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;
}