PATCH: PR binutils/3281: objcopy changes PT_GNU_RELRO when there is PT_TLS

H. J. Lu hjl@lucon.org
Tue Oct 24 07:14:00 GMT 2006


On Thu, Oct 19, 2006 at 11:30:37PM -0700, H. J. Lu wrote:
> On Thu, Oct 19, 2006 at 11:10:02PM -0700, H. J. Lu wrote:
> > On Thu, Oct 19, 2006 at 08:05:40AM -0700, H. J. Lu wrote:
> > > On Thu, Sep 28, 2006 at 03:09:16PM -0700, H. J. Lu wrote:
> > > > When linker creates PT_GNU_RELRO segment, it sets p_vaddr, p_paddr,
> > > > p_offset, p_filesz from the corresponding PT_LOAD segment and
> > > > set p_memsz to p_filesz, p_align to 1. My previous fix for PR 3015
> > > > only handles p_align for objcopy. PT_GNU_RELRO segment will be
> > > > different after objcopy if there is a PT_TLS segment. This patch
> > > > puts all PT_GNU_RELRO segment procossing for objcopy into
> > > > assign_file_positions_for_non_load_sections and uses the same logic
> > > > as linker.
> > > > 
> > > 
> > > Could someone please take a look at it:
> > > 
> > > http://sourceware.org/ml/binutils/2006-09/msg00376.html
> > > 
> > > Thanks.
> > > 
> > 
> > It turns out that there are other problems with PT_GNU_RELRO. SHF_TLS
> > sections can be in PT_GNU_RELRO segment. We got it wrong. Also we
> > may create a PT_NULL segment if there are no relro sections. I noticed
> > them when I ran "make check" with my patch for Linux/mips64 where
> > GNU_RELRO segment may only contains .tdata section.
> > 
> > This updated patch addresses those 2 problems.
> > 
> > 
> 
> We should ignore discarded sections.
> 

We should skip discarded, excluded and ignored sections.


H.J.
----
bfd/

2006-10-20  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/3281
	* elf-bfd.h (elf_obj_tdata): Remove relro.

	* elf.c (get_program_header_size): Check info->relro instead
	of elf_tdata (abfd)->relro.
	(_bfd_elf_map_sections_to_segments): Likewise.
	(assign_file_positions_for_load_sections): Don't set
	PT_GNU_RELRO segment alignment here.
	(assign_file_positions_for_non_load_sections): Properly set up
	PT_GNU_RELRO segment for copying executable/shared library.

include/elf/

2006-10-20  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/3281
	* internal.h (ELF_IS_SECTION_IN_SEGMENT): Allow SHF_TLS
	sections in PT_GNU_RELRO segments.

ld/

2006-10-20  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/3281
	* ldexp.h (ldexp_control): Add relro, relro_start_stat and
	relro_end_stat.

	* ldexp.c (fold_binary): Set expld.dataseg.relro to
	exp_dataseg_relro_start or exp_dataseg_relro_end when
	seeing DATA_SEGMENT_ALIGN or DATA_SEGMENT_RELRO_END,
	respectively.

	* ldlang.c (lang_size_sections_1): Properly set
	expld.dataseg.relro_start_stat and
	expld.dataseg.relro_end_stat.
	(size_relro_section_callback): New function.
	(lang_size_relro_sections_1): Likewise.
	(lang_size_relro_sections): Likewise.
	(lang_process): Call lang_size_relro_sections for
	non-relocatable link.

ld/testsuite/

2006-10-20  H.J. Lu  <hongjiu.lu@intel.com>

	PR binutils/3281
	* ld-elf/binutils.exp: Update "-z relro" tests to use relro.s.
	Add "-z relro" tests with TLS for objcopy.

	* ld-elf/relro.s: New file.

--- binutils/bfd/elf-bfd.h.relro	2006-10-20 09:28:37.000000000 -0700
+++ binutils/bfd/elf-bfd.h	2006-10-20 09:28:38.000000000 -0700
@@ -1375,9 +1375,6 @@ struct elf_obj_tdata
   /* Segment flags for the PT_GNU_STACK segment.  */
   unsigned int stack_flags;
 
-  /* Should the PT_GNU_RELRO segment be emitted?  */
-  bfd_boolean relro;
-
   /* Symbol version definitions in external objects.  */
   Elf_Internal_Verdef *verdef;
 
--- binutils/bfd/elf.c.relro	2006-10-20 09:28:38.000000000 -0700
+++ binutils/bfd/elf.c	2006-10-20 09:28:38.000000000 -0700
@@ -3637,7 +3637,7 @@ get_program_header_size (bfd *abfd, stru
       /* We need a PT_DYNAMIC segment.  */
       ++segs;
       
-      if (elf_tdata (abfd)->relro)
+      if (info->relro)
 	{
 	  /* We need a PT_GNU_RELRO segment only when there is a
 	     PT_DYNAMIC segment.  */
@@ -4223,7 +4223,7 @@ _bfd_elf_map_sections_to_segments (bfd *
 	  pm = &m->next;
 	}
 
-      if (dynsec != NULL && elf_tdata (abfd)->relro)
+      if (dynsec != NULL && info->relro)
 	{
 	  /* We make a PT_GNU_RELRO segment only when there is a
 	     PT_DYNAMIC segment.  */
@@ -4707,11 +4707,9 @@ assign_file_positions_for_load_sections 
 		    p->p_memsz += o->offset + o->size;
 		}
 
-	      if (p->p_type == PT_GNU_RELRO)
-		p->p_align = 1;
-	      else if (align > p->p_align
-		       && (p->p_type != PT_LOAD
-			   || (abfd->flags & D_PAGED) == 0))
+	      if (align > p->p_align
+		  && (p->p_type != PT_LOAD
+		      || (abfd->flags & D_PAGED) == 0))
 		p->p_align = align;
 	    }
 
@@ -4838,7 +4836,8 @@ assign_file_positions_for_non_load_secti
       if (m->count != 0)
 	{
 	  if (p->p_type != PT_LOAD
-	      && (p->p_type != PT_NOTE || bfd_get_format (abfd) != bfd_core))
+	      && (p->p_type != PT_NOTE
+		  || bfd_get_format (abfd) != bfd_core))
 	    {
 	      Elf_Internal_Shdr *hdr;
 	      BFD_ASSERT (!m->includes_filehdr && !m->includes_phdrs);
@@ -4849,7 +4848,33 @@ assign_file_positions_for_non_load_secti
 	      if (hdr->sh_type != SHT_NOBITS)
 		p->p_filesz += hdr->sh_size;
 
-	      p->p_offset = m->sections[0]->filepos;
+	      if (p->p_type == PT_GNU_RELRO)
+		{
+		  /* When we get here, we are copying executable
+		     or shared library. But we need to use the same
+		     linker logic.  */
+		  Elf_Internal_Phdr *lp;
+
+		  for (lp = phdrs; lp < phdrs + count; ++lp)
+		    {
+		      if (lp->p_type == PT_LOAD
+			  && lp->p_paddr == p->p_paddr)
+			break;
+		    }
+	  
+		  if (lp < phdrs + count)
+		    {
+		      p->p_filesz += p->p_vaddr - lp->p_vaddr;
+		      p->p_vaddr = lp->p_vaddr;
+		      p->p_offset = lp->p_offset;
+		      p->p_memsz = p->p_filesz;
+		      p->p_align = 1;
+		    }
+		  else
+		    abort ();
+		}
+	      else
+		p->p_offset = m->sections[0]->filepos;
 	    }
 	}
       else
--- binutils/bfd/elflink.c.relro	2006-10-20 09:28:38.000000000 -0700
+++ binutils/bfd/elflink.c	2006-10-20 09:28:38.000000000 -0700
@@ -5282,7 +5282,6 @@ bfd_elf_size_dynamic_sections (bfd *outp
   if (!is_elf_hash_table (info->hash))
     return TRUE;
 
-  elf_tdata (output_bfd)->relro = info->relro;
   if (info->execstack)
     elf_tdata (output_bfd)->stack_flags = PF_R | PF_W | PF_X;
   else if (info->noexecstack)
--- binutils/include/elf/internal.h.relro	2006-09-18 10:08:02.000000000 -0700
+++ binutils/include/elf/internal.h	2006-10-20 09:28:38.000000000 -0700
@@ -264,11 +264,12 @@ struct elf_segment_map
      || segment->p_type == PT_TLS) ? sec_hdr->sh_size : 0)
 
 /* Decide if the given sec_hdr is in the given segment.  PT_TLS segment
-   contains only SHF_TLS sections.  Only PT_LOAD and PT_TLS segments
-   can contain SHF_TLS sections.  */
+   contains only SHF_TLS sections.  Only PT_LOAD, PT_GNU_RELRO and
+   PT_TLS segments can contain SHF_TLS sections.  */
 #define ELF_IS_SECTION_IN_SEGMENT(sec_hdr, segment)		\
   (((((sec_hdr->sh_flags & SHF_TLS) != 0)			\
      && (segment->p_type == PT_TLS				\
+	 || segment->p_type == PT_GNU_RELRO			\
 	 || segment->p_type == PT_LOAD))			\
     || ((sec_hdr->sh_flags & SHF_TLS) == 0			\
 	&& segment->p_type != PT_TLS))				\
--- binutils/ld/ldexp.c.relro	2006-09-18 10:08:08.000000000 -0700
+++ binutils/ld/ldexp.c	2006-10-20 09:28:38.000000000 -0700
@@ -384,6 +384,7 @@ fold_binary (etree_type *tree)
 	      break;
 
 	    case DATA_SEGMENT_ALIGN:
+	      expld.dataseg.relro = exp_dataseg_relro_start;
 	      if (expld.phase != lang_first_phase_enum
 		  && expld.section == bfd_abs_section_ptr
 		  && (expld.dataseg.phase == exp_dataseg_none
@@ -419,6 +420,7 @@ fold_binary (etree_type *tree)
 	      break;
 
 	    case DATA_SEGMENT_RELRO_END:
+	      expld.dataseg.relro = exp_dataseg_relro_end;
 	      if (expld.phase != lang_first_phase_enum
 		  && (expld.dataseg.phase == exp_dataseg_align_seen
 		      || expld.dataseg.phase == exp_dataseg_adjust
--- binutils/ld/ldexp.h.relro	2006-09-18 10:08:08.000000000 -0700
+++ binutils/ld/ldexp.h	2006-10-20 09:28:38.000000000 -0700
@@ -97,6 +97,8 @@ typedef enum {
   lang_final_phase_enum
 } lang_phase_type;
 
+union lang_statement_union;
+
 struct ldexp_control {
   /* Modify expression evaluation depending on this.  */
   lang_phase_type phase;
@@ -124,6 +126,15 @@ struct ldexp_control {
     } phase;
 
     bfd_vma base, min_base, relro_end, end, pagesize, maxpagesize;
+
+    enum {
+      exp_dataseg_relro_none,
+      exp_dataseg_relro_start,
+      exp_dataseg_relro_end,
+    } relro;
+
+    union lang_statement_union *relro_start_stat;
+    union lang_statement_union *relro_end_stat;
   } dataseg;
 };
 
--- binutils/ld/ldlang.c.relro	2006-10-20 09:28:37.000000000 -0700
+++ binutils/ld/ldlang.c	2006-10-20 09:53:48.000000000 -0700
@@ -4633,10 +4633,32 @@ lang_size_sections_1
 	    bfd_vma newdot = dot;
 	    etree_type *tree = s->assignment_statement.exp;
 
+	    expld.dataseg.relro = exp_dataseg_relro_none;
+
 	    exp_fold_tree (tree,
 			   output_section_statement->bfd_section,
 			   &newdot);
 
+	    if (expld.dataseg.relro == exp_dataseg_relro_start)
+	      {
+		if (!expld.dataseg.relro_start_stat)
+		  expld.dataseg.relro_start_stat = s;
+		else
+		  {
+		    ASSERT (expld.dataseg.relro_start_stat == s);
+		  }
+	      }
+	    else if (expld.dataseg.relro == exp_dataseg_relro_end)
+	      {
+		if (!expld.dataseg.relro_end_stat)
+		  expld.dataseg.relro_end_stat = s;
+		else
+		  {
+		    ASSERT (expld.dataseg.relro_end_stat == s);
+		  }
+	      }
+	    expld.dataseg.relro = exp_dataseg_relro_none;
+
 	    /* This symbol is relative to this section.  */
 	    if ((tree->type.node_class == etree_provided 
 		 || tree->type.node_class == etree_assign)
@@ -5613,6 +5635,81 @@ lang_gc_sections (void)
     bfd_gc_sections (output_bfd, &link_info);
 }
 
+/* Worker for lang_size_relro_sections_1.  */
+
+static void
+size_relro_section_callback (lang_wild_statement_type *ptr ATTRIBUTE_UNUSED,
+			     struct wildcard_list *sec ATTRIBUTE_UNUSED,
+			     asection *section,
+			     lang_input_statement_type *file ATTRIBUTE_UNUSED,
+			     void *data)
+{
+  /* Discarded, excluded and ignored sections effectively have zero
+     size.  */
+  if (section->output_section != NULL
+      && section->output_section->owner == output_bfd
+      && (section->output_section->flags & SEC_EXCLUDE) == 0
+      && !IGNORE_SECTION (section)
+      && section->size != 0)
+    {
+      bfd_boolean *has_relro_section = (bfd_boolean *) data;
+      *has_relro_section = TRUE;
+    }
+}
+
+/* Iterate over sections for relro sections.  */
+
+static void
+lang_size_relro_sections_1 (lang_statement_union_type *s,
+			    bfd_boolean *has_relro_section)
+{
+  if (*has_relro_section)
+    return;
+
+  for (; s != NULL; s = s->header.next)
+    {
+      if (s == expld.dataseg.relro_end_stat)
+	break;
+
+      switch (s->header.type)
+	{
+	case lang_wild_statement_enum:
+	  walk_wild (&s->wild_statement,
+		     size_relro_section_callback,
+		     has_relro_section);
+	  break;
+	case lang_constructors_statement_enum:
+	  lang_size_relro_sections_1 (constructor_list.head,
+				      has_relro_section);
+	  break;
+	case lang_output_section_statement_enum:
+	  lang_size_relro_sections_1 (s->output_section_statement.children.head,
+				      has_relro_section);
+	  break;
+	case lang_group_statement_enum:
+	  lang_size_relro_sections_1 (s->group_statement.children.head,
+				      has_relro_section);
+	  break;
+	default:
+	  break;
+	}
+    }
+}
+
+static void
+lang_size_relro_sections (void)
+{
+  bfd_boolean has_relro_section = FALSE;
+
+  /* Check all sections in the link script.  */
+
+  lang_size_relro_sections_1 (expld.dataseg.relro_start_stat,
+			      &has_relro_section);
+
+  if (!has_relro_section)
+    link_info.relro = FALSE;
+}
+
 /* Relax all sections until bfd_relax_section gives up.  */
 
 static void
@@ -5738,6 +5835,10 @@ lang_process (void)
      section positions, since they will affect SIZEOF_HEADERS.  */
   lang_record_phdrs ();
 
+  /* Check relro sections.  */
+  if (link_info.relro && ! link_info.relocatable)
+    lang_size_relro_sections ();
+
   /* Size up the sections.  */
   lang_size_sections (NULL, !command_line.relax);
 
--- binutils/ld/testsuite/ld-elf/binutils.exp.relro	2006-09-18 10:08:09.000000000 -0700
+++ binutils/ld/testsuite/ld-elf/binutils.exp	2006-10-20 09:28:38.000000000 -0700
@@ -101,24 +101,33 @@ binutils_test strip "-shared" maxpage1
 binutils_test objcopy "" maxpage1
 binutils_test objcopy "-shared" maxpage1
 
-binutils_test strip "-z relro" maxpage1
-binutils_test strip "-z relro -shared" maxpage1
-binutils_test objcopy "-z relro" maxpage1
-binutils_test objcopy "-z relro -shared" maxpage1
+binutils_test strip "-z relro" relro
+binutils_test strip "-z relro -shared" relro
+binutils_test objcopy "-z relro" relro
+binutils_test objcopy "-z relro -shared" relro
 
 binutils_test objcopy "" tbss1
+binutils_test objcopy "-z relro" tbss1
 binutils_test objcopy "-shared" tbss1
+binutils_test objcopy "-shared -z relro" tbss1
 binutils_test objcopy "-z max-page-size=0x100000" tbss1
 binutils_test objcopy "-z max-page-size=0x100000 -z common-page-size=0x1000" tbss1
 binutils_test objcopy "" tdata1
+binutils_test objcopy "-z relro" tdata1
 binutils_test objcopy "-shared" tdata1
+binutils_test objcopy "-shared -z relro" tdata1
 binutils_test objcopy "-z max-page-size=0x100000" tdata1
 binutils_test objcopy "-z max-page-size=0x100000 -z common-page-size=0x1000" tdata1
 binutils_test objcopy "" tbss2
+binutils_test objcopy "-z relro" tbss2
 binutils_test objcopy "-shared" tbss2
+binutils_test objcopy "-shared -z relro" tbss2
 binutils_test objcopy "-z max-page-size=0x100000" tbss2
 binutils_test objcopy "-z max-page-size=0x100000 -z common-page-size=0x1000" tbss2
-binutils_test objcopy "-z max-page-size=0x100000" tdata2
+
 binutils_test objcopy "" tdata2
+binutils_test objcopy "-z relro" tdata2
 binutils_test objcopy "-shared" tdata2
+binutils_test objcopy "-shared -z relro" tdata2
+binutils_test objcopy "-z max-page-size=0x100000" tdata2
 binutils_test objcopy "-z max-page-size=0x100000 -z common-page-size=0x1000" tdata2
--- binutils/ld/testsuite/ld-elf/relro.s.relro	2006-10-20 09:28:38.000000000 -0700
+++ binutils/ld/testsuite/ld-elf/relro.s	2006-10-20 09:28:38.000000000 -0700
@@ -0,0 +1,14 @@
+	.globl main
+	.globl start
+	.globl _start
+	.globl __start
+	.text
+main:
+start:
+_start:
+__start:
+	.long	0
+	.data
+	.long	0
+	.section .data.rel.ro,"aw",%progbits
+	.long	0



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