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Re: PATCH: PR binutils/3281: objcopy changes PT_GNU_RELRO when there is PT_TLS
On Fri, Oct 27, 2006 at 10:49:20AM -0700, H. J. Lu wrote:
> On Fri, Oct 27, 2006 at 02:35:56PM +0930, Alan Modra wrote:
> > On Mon, Oct 23, 2006 at 10:55:59PM -0700, H. J. Lu wrote:
> > > + 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 ();
> > > + }
> >
> > I don't think this is going to work in all cases. objcopy can do some
> > really nasty things as far as GNU_RELRO segment is concerned, deleting
> > sections, adding sections, changing section lmas. I think instead
> > you should set the GNU_RELRO segment info from the section map, and
> > try to get the section map correct in rewrite_elf_program_header. I
> > noticed at least one problem with rewrite_elf_program_header "Step
> > Three": It should not be allowed to split a GNU_RELRO segment into
> > two due to gaps.
> >
>
> My patch works with deleted sections, which won't reach "Step Three".
> I am not sure if we should keep GNU_RELRO segment when we add section
> or change section lmas.
I think we should delete GNU_RELRO segment if a section is added or
modified.
>
> > > +lang_size_relro_sections (void)
> >
> > Should probably be called lang_find_relro_sections. You aren't doing
> > any sizing here.
>
> I will change it.
>
>
Here is the updated patch.
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.
(elf_section_status): New enum.
(rewrite_elf_program_header): Add elf_section_status. Remove
PT_GNU_RELRO segment if a section is modified.
(copy_private_bfd_data): Updated rewrite_elf_program_header
call.
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.
(find_relro_section_callback): New function.
(lang_find_relro_sections_1): Likewise.
(lang_find_relro_sections): Likewise.
(lang_process): Call lang_find_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 2006-10-27 10:20:57.000000000 -0700
+++ binutils/bfd/elf-bfd.h 2006-10-27 10:20:57.000000000 -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 2006-10-27 10:20:57.000000000 -0700
+++ binutils/bfd/elf.c 2006-10-27 11:24:53.000000000 -0700
@@ -3631,7 +3631,7 @@ 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. */
@@ -4119,7 +4119,7 @@ _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. */
@@ -4602,11 +4602,9 @@ 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;
}
@@ -4733,7 +4731,8 @@ 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);
@@ -4744,7 +4743,33 @@ 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
@@ -5172,8 +5197,17 @@ _bfd_elf_symbol_from_bfd_symbol (bfd *ab
/* Rewrite program header information. */
+enum elf_section_status
+{
+ unknown,
+ added,
+ removed,
+ modified
+};
+
static bfd_boolean
-rewrite_elf_program_header (bfd *ibfd, bfd *obfd)
+rewrite_elf_program_header (bfd *ibfd, bfd *obfd,
+ enum elf_section_status status)
{
Elf_Internal_Ehdr *iehdr;
struct elf_segment_map *map;
@@ -5321,7 +5355,14 @@ rewrite_elf_program_header (bfd *ibfd, b
}
if (segment->p_type != PT_LOAD)
- continue;
+ {
+ /* If a section is added or mofied, remove PT_GNU_RELRO
+ segment. */
+ if (status != removed &&
+ segment->p_type == PT_GNU_RELRO)
+ segment->p_type = PT_NULL;
+ continue;
+ }
/* Determine if this segment overlaps any previous segments. */
for (j = 0, segment2 = elf_tdata (ibfd)->phdr; j < i; j++, segment2 ++)
@@ -5858,6 +5899,12 @@ copy_elf_program_header (bfd *ibfd, bfd
static bfd_boolean
copy_private_bfd_data (bfd *ibfd, bfd *obfd)
{
+ enum elf_section_status status;
+ Elf_Internal_Phdr *segment;
+ asection *section, *osec;
+ unsigned int i, num_segments;
+ Elf_Internal_Shdr *this_hdr;
+
if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
|| bfd_get_flavour (obfd) != bfd_target_elf_flavour)
return TRUE;
@@ -5865,14 +5912,11 @@ copy_private_bfd_data (bfd *ibfd, bfd *o
if (elf_tdata (ibfd)->phdr == NULL)
return TRUE;
+ status = unknown;
if (ibfd->xvec == obfd->xvec)
{
/* Check if any sections in the input BFD covered by ELF program
header are changed. */
- Elf_Internal_Phdr *segment;
- asection *section, *osec;
- unsigned int i, num_segments;
- Elf_Internal_Shdr *this_hdr;
/* Initialize the segment mark field. */
for (section = obfd->sections; section != NULL;
@@ -5917,7 +5961,10 @@ copy_private_bfd_data (bfd *ibfd, bfd *o
section = section->next)
{
if (section->segment_mark == FALSE)
- goto rewrite;
+ {
+ status = added;
+ goto rewrite;
+ }
else
section->segment_mark = FALSE;
}
@@ -5926,7 +5973,46 @@ copy_private_bfd_data (bfd *ibfd, bfd *o
}
rewrite:
- return rewrite_elf_program_header (ibfd, obfd);
+ if (status == unknown)
+ {
+ /* We need to find out how we are changed. */
+ num_segments = elf_elfheader (ibfd)->e_phnum;
+ for (i = 0, segment = elf_tdata (ibfd)->phdr;
+ i < num_segments;
+ i++, segment++)
+ {
+ for (section = ibfd->sections;
+ section != NULL; section = section->next)
+ {
+ /* We mark the output section so that we know it comes
+ from the input BFD. */
+ osec = section->output_section;
+ if (osec)
+ osec->segment_mark = TRUE;
+
+ /* Check if this section is covered by the segment. */
+ this_hdr = &(elf_section_data(section)->this_hdr);
+ if (ELF_IS_SECTION_IN_SEGMENT_FILE (this_hdr, segment))
+ {
+ if (osec == NULL)
+ status = removed;
+ else if (section->flags != osec->flags
+ || section->lma != osec->lma
+ || section->vma != osec->vma
+ || section->size != osec->size
+ || section->rawsize != osec->rawsize
+ || section->alignment_power != osec->alignment_power)
+ {
+ /* Stop if a section is modified. */
+ status = modified;
+ break;
+ }
+ }
+ }
+ }
+ }
+ BFD_ASSERT (status != unknown);
+ return rewrite_elf_program_header (ibfd, obfd, status);
}
/* Initialize private output section information from input section. */
--- binutils/bfd/elflink.c.relro 2006-10-27 10:20:57.000000000 -0700
+++ binutils/bfd/elflink.c 2006-10-27 10:20:57.000000000 -0700
@@ -5266,7 +5266,6 @@ 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 2006-05-31 22:40:24.000000000 -0700
+++ binutils/include/elf/internal.h 2006-10-27 10:20:57.000000000 -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 2006-08-22 18:35:31.000000000 -0700
+++ binutils/ld/ldexp.c 2006-10-27 10:20:57.000000000 -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 2005-08-05 06:52:13.000000000 -0700
+++ binutils/ld/ldexp.h 2006-10-27 10:20:57.000000000 -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 2006-10-27 10:20:57.000000000 -0700
+++ binutils/ld/ldlang.c 2006-10-27 10:20:57.000000000 -0700
@@ -4626,10 +4626,32 @@ 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)
@@ -5606,6 +5628,81 @@ lang_gc_sections (void)
bfd_gc_sections (output_bfd, &link_info);
}
+/* Worker for lang_find_relro_sections_1. */
+
+static void
+find_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_find_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,
+ find_relro_section_callback,
+ has_relro_section);
+ break;
+ case lang_constructors_statement_enum:
+ lang_find_relro_sections_1 (constructor_list.head,
+ has_relro_section);
+ break;
+ case lang_output_section_statement_enum:
+ lang_find_relro_sections_1 (s->output_section_statement.children.head,
+ has_relro_section);
+ break;
+ case lang_group_statement_enum:
+ lang_find_relro_sections_1 (s->group_statement.children.head,
+ has_relro_section);
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+static void
+lang_find_relro_sections (void)
+{
+ bfd_boolean has_relro_section = FALSE;
+
+ /* Check all sections in the link script. */
+
+ lang_find_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
@@ -5731,6 +5828,10 @@ 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_find_relro_sections ();
+
/* Size up the sections. */
lang_size_sections (NULL, !command_line.relax);
--- binutils/ld/testsuite/ld-elf/binutils.exp.relro 2006-08-16 19:04:53.000000000 -0700
+++ binutils/ld/testsuite/ld-elf/binutils.exp 2006-10-27 10:20:57.000000000 -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 2006-10-27 10:20:57.000000000 -0700
+++ binutils/ld/testsuite/ld-elf/relro.s 2006-10-27 10:20:57.000000000 -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