ld: Support ELF GNU program properties

From .note.gnu.property section in each ELF input, we build a list of
GNU properties if .note.gnu.property section isn't corrupt.  The unknown
properties are ignored.  All property lists in relocatable inputs are
merged into an output property list.  When -z stack-size=N is used and
N isn't 0, the GNU_PROPERTY_STACK_SIZE property will be merged with or
added to the output property list.  .note.gnu.property section is
generated in output from the output property list.

bfd/

	* Makefile.am (BFD32_BACKENDS): Add elf-properties.lo.
	(BFD32_BACKENDS_CFILES): Add elf-properties.c.
	* configure.ac (elf): Add elf-properties.lo.
	* Makefile.in: Regenerated.
	* configure: Likewise.
	* elf-bfd.h (elf_property_kind): New.
	(elf_property): Likewise.
	(elf_property_list): Likewise.
	(elf_properties): Likewise.
	(_bfd_elf_parse_gnu_properties): Likewise.
	(_bfd_elf_get_property): Likewise.
	(_bfd_elf_link_setup_gnu_properties): Likewise.
	(elf_backend_data): Add parse_gnu_properties, merge_gnu_properties
	and setup_gnu_properties.
	(elf_obj_tdata): Add properties.
	* elf-properties.c: New file.
	* elf32-i386.c (elf_i386_parse_gnu_properties): New.
	(elf_i386_merge_gnu_properties): Likewise.
	(elf_backend_parse_gnu_properties): Likewise.
	(elf_backend_merge_gnu_properties): Likewise.
	* elf64-x86-64.c (elf_x86_64_parse_gnu_properties): Likewise.
	(elf_x86_64_merge_gnu_properties): Likewise.
	(elf_backend_parse_gnu_properties): Likewise.
	(elf_backend_merge_gnu_properties): Likewise.
	* elfxx-target.h (elf_backend_merge_gnu_properties): Likewise.
	(elf_backend_parse_gnu_properties): Likewise.
	(elf_backend_setup_gnu_properties): Likewise.
	(elfNN_bed): Add elf_backend_parse_gnu_properties,
	elf_backend_merge_gnu_properties and
	elf_backend_setup_gnu_properties.

ld/

	* ld/NEWS: Mention support for ELF GNU program properties.
	* emultempl/elf32.em (gld${EMULATION_NAME}_after_open): Call
	ELF setup_gnu_properties.
	* testsuite/ld-i386/i386.exp: Run property tests for Linux/i386.
	* testsuite/ld-i386/pass.c: New file.
	* testsuite/ld-i386/property-1.r: Likewise.
	* testsuite/ld-i386/property-2.r: Likewise.
	* testsuite/ld-i386/property-3.r: Likewise.
	* testsuite/ld-i386/property-4.r: Likewise.
	* testsuite/ld-i386/property-5.r: Likewise.
	* testsuite/ld-i386/property-6.r: Likewise.
	* testsuite/ld-i386/property-6a.c: Likewise.
	* testsuite/ld-i386/property-6b.c: Likewise.
	* testsuite/ld-i386/property-6c.S: Likewise.
	* testsuite/ld-i386/property-7.r: Likewise.
	* testsuite/ld-i386/property-no-copy.S: Likewise.
	* testsuite/ld-i386/property-stack.S: Likewise.
	* testsuite/ld-i386/property-unsorted-1.S: Likewise.
	* testsuite/ld-i386/property-unsorted-2.S: Likewise.
	* testsuite/ld-i386/property-x86-1.S: Likewise.
	* testsuite/ld-i386/property-x86-2.S: Likewise.
	* testsuite/ld-x86-64/pass.c: Likewise.
	* testsuite/ld-x86-64/property-1.r: Likewise.
	* testsuite/ld-x86-64/property-2.r: Likewise.
	* testsuite/ld-x86-64/property-3.r: Likewise.
	* testsuite/ld-x86-64/property-4.r: Likewise.
	* testsuite/ld-x86-64/property-5.r: Likewise.
	* testsuite/ld-x86-64/property-6.r: Likewise.
	* testsuite/ld-x86-64/property-6a.c: Likewise.
	* testsuite/ld-x86-64/property-6b.c: Likewise.
	* testsuite/ld-x86-64/property-6c.S: Likewise.
	* testsuite/ld-x86-64/property-7.r: Likewise.
	* testsuite/ld-x86-64/property-no-copy.S: Likewise.
	* testsuite/ld-x86-64/property-stack.S: Likewise.
	* testsuite/ld-x86-64/property-unsorted-1.S: Likewise.
	* testsuite/ld-x86-64/property-unsorted-2.S: Likewise.
	* testsuite/ld-x86-64/property-x86-1.S: Likewise.
	* testsuite/ld-x86-64/property-x86-2.S: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run property tests for
	Linux/x86-64.

1 files changed, 483 insertions, 0 deletions

diff --git a/bfd/elf-properties.c b/bfd/elf-properties.c
new file mode 100644
index 0000000..a0456f8
--- /dev/null
+++ b/bfd/elf-properties.c
@@ -0,0 +1,483 @@
+/* ELF program property support.
+   Copyright (C) 2017 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\n"),
+	 abfd, note->type, note->descsz);
+      return FALSE;
+    }
+
+  while (1)
+    {
+      unsigned int type = bfd_h_get_32 (abfd, ptr);
+      unsigned int datasz = bfd_h_get_32 (abfd, ptr + 4);
+      elf_property *prop;
+
+      ptr += 8;
+
+      if ((ptr + datasz) > ptr_end)
+	{
+	  _bfd_error_handler
+	    (_("warning: %B: corrupt GNU_PROPERTY_TYPE (%ld) type (0x%x) datasz: 0x%x\n"),
+	     abfd, note->type, type, datasz);
+	  /* Clear all properties.  */
+	  elf_properties (abfd) = NULL;
+	  return FALSE;
+	}
+
+      if (type >= GNU_PROPERTY_LOPROC)
+	{
+	  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\n"),
+		     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\n"),
+		     abfd, datasz);
+		  /* Clear all properties.  */
+		  elf_properties (abfd) = NULL;
+		  return FALSE;
+		}
+	      prop = _bfd_elf_get_property (abfd, type, datasz);
+	      prop->pr_kind = property_number;
+	      goto next;
+
+	    default:
+	      break;
+	    }
+	}
+
+      _bfd_error_handler
+	(_("warning: %B: unsupported GNU_PROPERTY_TYPE (%ld) type: 0x%x\n"),
+	 abfd, note->type, type);
+
+next:
+      ptr += (datasz + (align_size - 1)) & ~ (align_size - 1);
+      if (ptr == ptr_end)
+	break;
+
+      if (ptr > (ptr_end - 8))
+	goto bad_size;
+    }
+
+  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 (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 (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 (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 (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 (abfd, NULL, &p->property))
+      {
+	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.  */
+
+void
+_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
+	&& bfd_count_sections (abfd) != 0
+	&& elf_properties (abfd) != NULL)
+      {
+	has_properties = TRUE;
+
+	/* Ignore GNU properties from ELF objects with different machine
+	   code or class.  */
+	if ((elf_machine_code
+	     == get_elf_backend_data (abfd)->elf_machine_code)
+	    && (elfclass
+		== get_elf_backend_data (abfd)->s->elfclass))
+	  {
+	    /* 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;
+
+  /* Merge .note.gnu.property sections.  */
+  for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
+    if (abfd != first_pbfd && bfd_count_sections (abfd) != 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 (first_pbfd, listp);
+
+	if (list != NULL)
+	  {
+	    /* Discard .note.gnu.property section in the rest inputs.  */
+	    sec = bfd_get_section_by_name (abfd,
+					   NOTE_GNU_PROPERTY_SECTION_NAME);
+	    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);
+
+      /* 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;
+	}
+
+      /* 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;
+    }
+}