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readelf: report DF_1_PIE as "Position-Independent Executable"

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I finally found time to teach readelf to identify PIEs in the file
header display and program header display.  So in place of
"DYN (Shared object file)" which isn't completely true, show
"DYN (Position-Independent Executable file)".

It requires a little bit of untangling code in readelf due to
process_program_headers setting up dynamic_addr and dynamic_size,
needed to scan .dynamic for the DT_FLAGS_1 entry, and
process_program_headers itself wanting to display the file type in
some cases.  At first I modified process_program_header using a
"probe" parameter similar to get_section_headers in order to inhibit
output, but decided it was cleaner to separate out
locate_dynamic_sections.

binutils/
	* readelf.c (locate_dynamic_section, is_pie): New functions.
	(get_file_type): Replace e_type parameter with filedata.  Call
	is_pie for ET_DYN.  Update all callers.
	(process_program_headers): Use local variables dynamic_addr and
	dynamic_size, updating filedata on exit from function.  Set
	dynamic_size of 1 to indicate no dynamic section or segment.
	Update tests of dynamic_size throughout.
	* testsuite/binutils-all/x86-64/pr27708.dump: Update expected output.
ld/
	* testsuite/ld-pie/vaddr-0.d: Update expected output.
gdb/
	* testsuite/lib/gdb.exp (exec_is_pie): Match new PIE readelf output.
This commit is contained in:
Alan Modra 2021-06-11 14:23:57 +09:30
parent 79afa8caab
commit 93df3340fd
7 changed files with 156 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
binutils/ChangeLog
View File

@ -1,3 +1,14 @@
2021-06-15 Alan Modra <amodra@gmail.com>
* readelf.c (locate_dynamic_section, is_pie): New functions.
(get_file_type): Replace e_type parameter with filedata. Call
is_pie for ET_DYN. Update all callers.
(process_program_headers): Use local variables dynamic_addr and
dynamic_size, updating filedata on exit from function. Set
dynamic_size of 1 to indicate no dynamic section or segment.
Update tests of dynamic_size throughout.
* testsuite/binutils-all/x86-64/pr27708.dump: Update expected output.
2021-06-14 Eric Botcazou <ebotcazou@adacore.com>
* dwarf.c (struct abbrev_attr): Change type of implicit_const.

162
binutils/readelf.c
View File

@ -2339,9 +2339,96 @@ get_dynamic_type (Filedata * filedata, unsigned long type)
}
}
static char *
get_file_type (unsigned e_type)
static bool get_program_headers (Filedata *);
static bool get_dynamic_section (Filedata *);
static void
locate_dynamic_section (Filedata *filedata)
{
unsigned long dynamic_addr = 0;
bfd_size_type dynamic_size = 0;
if (filedata->file_header.e_phnum != 0
&& get_program_headers (filedata))
{
Elf_Internal_Phdr *segment;
unsigned int i;
for (i = 0, segment = filedata->program_headers;
i < filedata->file_header.e_phnum;
i++, segment++)
{
if (segment->p_type == PT_DYNAMIC)
{
dynamic_addr = segment->p_offset;
dynamic_size = segment->p_filesz;
if (filedata->section_headers != NULL)
{
Elf_Internal_Shdr *sec;
sec = find_section (filedata, ".dynamic");
if (sec != NULL)
{
if (sec->sh_size == 0
|| sec->sh_type == SHT_NOBITS)
{
dynamic_addr = 0;
dynamic_size = 0;
}
else
{
dynamic_addr = sec->sh_offset;
dynamic_size = sec->sh_size;
}
}
}
if (dynamic_addr > filedata->file_size
|| (dynamic_size > filedata->file_size - dynamic_addr))
{
dynamic_addr = 0;
dynamic_size = 0;
}
break;
}
}
}
filedata->dynamic_addr = dynamic_addr;
filedata->dynamic_size = dynamic_size ? dynamic_size : 1;
}
static bool
is_pie (Filedata *filedata)
{
Elf_Internal_Dyn *entry;
if (filedata->dynamic_size == 0)
locate_dynamic_section (filedata);
if (filedata->dynamic_size <= 1)
return false;
if (!get_dynamic_section (filedata))
return false;
for (entry = filedata->dynamic_section;
entry < filedata->dynamic_section + filedata->dynamic_nent;
entry++)
{
if (entry->d_tag == DT_FLAGS_1)
{
if ((entry->d_un.d_val & DF_1_PIE) != 0)
return true;
break;
}
}
return false;
}
static char *
get_file_type (Filedata *filedata)
{
unsigned e_type = filedata->file_header.e_type;
static char buff[64];
switch (e_type)
@ -2349,7 +2436,11 @@ get_file_type (unsigned e_type)
case ET_NONE: return _("NONE (None)");
case ET_REL: return _("REL (Relocatable file)");
case ET_EXEC: return _("EXEC (Executable file)");
case ET_DYN: return _("DYN (Shared object file)");
case ET_DYN:
if (is_pie (filedata))
return _("DYN (Position-Independent Executable file)");
else
return _("DYN (Shared object file)");
case ET_CORE: return _("CORE (Core file)");
default:
@ -5168,7 +5259,7 @@ process_file_header (Filedata * filedata)
printf (_(" ABI Version: %d\n"),
header->e_ident[EI_ABIVERSION]);
printf (_(" Type: %s\n"),
get_file_type (header->e_type));
get_file_type (filedata));
printf (_(" Machine: %s\n"),
get_machine_name (header->e_machine));
printf (_(" Version: 0x%lx\n"),
@ -5379,27 +5470,21 @@ get_program_headers (Filedata * filedata)
return false;
}
/* Returns TRUE if the program headers were loaded. */
/* Print program header info and locate dynamic section. */
static bool
static void
process_program_headers (Filedata * filedata)
{
Elf_Internal_Phdr * segment;
unsigned int i;
Elf_Internal_Phdr * previous_load = NULL;
filedata->dynamic_addr = 0;
filedata->dynamic_size = 0;
if (filedata->file_header.e_phnum == 0)
{
/* PR binutils/12467. */
if (filedata->file_header.e_phoff != 0)
{
warn (_("possibly corrupt ELF header - it has a non-zero program"
" header offset, but no program headers\n"));
return false;
}
else if (do_segments)
{
if (filedata->is_separate)
@ -5408,17 +5493,16 @@ process_program_headers (Filedata * filedata)
else
printf (_("\nThere are no program headers in this file.\n"));
}
return true;
goto no_headers;
}
if (do_segments && !do_header)
{
if (filedata->is_separate)
printf ("\nIn linked file '%s' the ELF file type is %s\n",
filedata->file_name,
get_file_type (filedata->file_header.e_type));
filedata->file_name, get_file_type (filedata));
else
printf (_("\nElf file type is %s\n"), get_file_type (filedata->file_header.e_type));
printf (_("\nElf file type is %s\n"), get_file_type (filedata));
printf (_("Entry point 0x%s\n"), bfd_vmatoa ("x", filedata->file_header.e_entry));
printf (ngettext ("There is %d program header, starting at offset %s\n",
"There are %d program headers, starting at offset %s\n",
@ -5428,7 +5512,7 @@ process_program_headers (Filedata * filedata)
}
if (! get_program_headers (filedata))
return true;
goto no_headers;
if (do_segments)
{
@ -5452,6 +5536,8 @@ process_program_headers (Filedata * filedata)
}
}
unsigned long dynamic_addr = 0;
bfd_size_type dynamic_size = 0;
for (i = 0, segment = filedata->program_headers;
i < filedata->file_header.e_phnum;
i++, segment++)
@ -5577,13 +5663,13 @@ process_program_headers (Filedata * filedata)
break;
case PT_DYNAMIC:
if (filedata->dynamic_addr)
if (dynamic_addr)
error (_("more than one dynamic segment\n"));
/* By default, assume that the .dynamic section is the first
section in the DYNAMIC segment. */
filedata->dynamic_addr = segment->p_offset;
filedata->dynamic_size = segment->p_filesz;
dynamic_addr = segment->p_offset;
dynamic_size = segment->p_filesz;
/* Try to locate the .dynamic section. If there is
a section header table, we can easily locate it. */
@ -5603,18 +5689,19 @@ process_program_headers (Filedata * filedata)
if (sec->sh_type == SHT_NOBITS)
{
filedata->dynamic_size = 0;
dynamic_addr = 0;
dynamic_size = 0;
break;
}
filedata->dynamic_addr = sec->sh_offset;
filedata->dynamic_size = sec->sh_size;
dynamic_addr = sec->sh_offset;
dynamic_size = sec->sh_size;
/* The PT_DYNAMIC segment, which is used by the run-time
loader, should exactly match the .dynamic section. */
if (do_checks
&& (filedata->dynamic_addr != segment->p_offset
|| filedata->dynamic_size != segment->p_filesz))
&& (dynamic_addr != segment->p_offset
|| dynamic_size != segment->p_filesz))
warn (_("\
the .dynamic section is not the same as the dynamic segment\n"));
}
@ -5623,12 +5710,12 @@ the .dynamic section is not the same as the dynamic segment\n"));
segment. Check this after matching against the section headers
so we don't warn on debuginfo file (which have NOBITS .dynamic
sections). */
if (filedata->dynamic_addr > filedata->file_size
|| (filedata->dynamic_size
> filedata->file_size - filedata->dynamic_addr))
if (dynamic_addr > filedata->file_size
|| (dynamic_size > filedata->file_size - dynamic_addr))
{
error (_("the dynamic segment offset + size exceeds the size of the file\n"));
filedata->dynamic_addr = filedata->dynamic_size = 0;
dynamic_addr = 0;
dynamic_size = 0;
}
break;
@ -5685,7 +5772,13 @@ the .dynamic section is not the same as the dynamic segment\n"));
}
}
return true;
filedata->dynamic_addr = dynamic_addr;
filedata->dynamic_size = dynamic_size ? dynamic_size : 1;
return;
no_headers:
filedata->dynamic_addr = 0;
filedata->dynamic_size = 1;
}
@ -10610,7 +10703,7 @@ process_dynamic_section (Filedata * filedata)
{
Elf_Internal_Dyn * entry;
if (filedata->dynamic_size == 0)
if (filedata->dynamic_size <= 1)
{
if (do_dynamic)
{
@ -21374,8 +21467,8 @@ process_object (Filedata * filedata)
/* Without loaded section groups we cannot process unwind. */
do_unwind = false;
res = process_program_headers (filedata);
if (res)
process_program_headers (filedata);
res = process_dynamic_section (filedata);
if (! process_relocs (filedata))
@ -21422,8 +21515,7 @@ process_object (Filedata * filedata)
{
if (! process_section_groups (d->handle))
res = false;
if (! process_program_headers (d->handle))
res = false;
process_program_headers (d->handle);
if (! process_dynamic_section (d->handle))
res = false;
if (! process_relocs (d->handle))

2
binutils/testsuite/binutils-all/x86-64/pr27708.dump
View File

@ -1,5 +1,5 @@
Elf file type is DYN (Shared object file)
Elf file type is DYN (Position-Independent Executable file)
Entry point 0x5f0
There are 11 program headers, starting at offset 64

4
gdb/ChangeLog
View File

@ -1,3 +1,7 @@
2021-06-15 Alan Modra <amodra@gmail.com>
* testsuite/lib/gdb.exp (exec_is_pie): Match new PIE readelf output.
2021-06-14 Mike Frysinger <vapier@gentoo.org>
* Makefile.in (GNULIB_BUILDDIR): Rename to ...

2
gdb/testsuite/lib/gdb.exp
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@ -6078,7 +6078,7 @@ proc exec_is_pie { executable } {
if { $res != 0 } {
return -1
}
set res [regexp -line {^[ \t]*Type:[ \t]*DYN \(Shared object file\)$} \
set res [regexp -line {^[ \t]*Type:[ \t]*DYN \((Position-Independent Executable|Shared object) file\)$} \
$output]
if { $res == 1 } {
return 1

4
ld/ChangeLog
View File

@ -1,3 +1,7 @@
2021-06-15 Alan Modra <amodra@gmail.com>
* testsuite/ld-pie/vaddr-0.d: Update expected output.
2021-06-11 Alan Modra <amodra@gmail.com>
PR 27952

2
ld/testsuite/ld-pie/vaddr-0.d
View File

@ -5,5 +5,5 @@
ELF Header:
#...
Type: DYN \(Shared object file\)
Type: DYN \(Position-Independent Executable file\)
#pass