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Bug 19961 - Distinguish between PI executable and shared library

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In the ELF format, Position Independent Executables (aka PIE) and
shared libraries are marked as being of type ET_DYN.  So just looking
at the type of the ELF file is not enough to discriminate a position
independent executable from a shared library.

And this is the problem.  Libabigail just looks at the type of the ELF
file to discriminate PIE binaries from shared libraries binaries.

So it treats both kinds of binaries as being shared libraries.  When
we run abipkgdiff with the --dso-only option, the tool considers both
PIEs and shared libraries, even though the intent of the --dso-only
option is have the tool consider shared libraries only.

With this patch, we introduce a new enumerator ELF_TYPE_PI_EXEC (to
the elf_type enum) for PIE binaries.  From now on, a file will be
properly recognized as being of the ELF_TYPE_DSO kind only if it is a
shared library.

	* include/abg-dwarf-reader.h (elf_type): Add new enumerator
	ELF_TYPE_PI_EXEC.
	* src/abg-dwarf-reader.cc
	(lookup_data_tag_from_dynamic_segment): New function for
	data tag lookup in dynamic segment of an elf
	(elf_file_type): Return ELF_TYPE_PI_EXEC file type for
	a PI executable.
	(get_elf_file_type): Change this to take an elf handle.
	(get_type_of_elf_file): New function that got factorized out of ...
	(load_dt_soname_and_needed): ... this one.
	* tools/abipkgdiff.cc (create_maps_of_package_content): Also
	consider ELF_TYPE_PI_EXEC file type.
	(compare): Likewise.
	* tests/test-diff-pkg.cc (in_out_specs): Test case additions
	* tests/data/Makefile.am: Include test files
	* tests/data/test-diff-pkg/tarpkg-1-dir1.tar.gz: New test data
	* tests/data/test-diff-pkg/tarpkg-1-dir2.tar.gz: New test data
	* tests/data/test-diff-pkg/tarpkg-1-report-0.txt: New test result

Signed-off-by: Sinny Kumari <sinny@redhat.com>
Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Sinny Kumari 2016-04-20 00:01:56 +05:30 committed by Dodji Seketeli
parent b6c6a65c5a
commit 8944ceb9ef
8 changed files with 140 additions and 93 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/abg-dwarf-reader.h
View File

@ -74,6 +74,7 @@ operator&=(status&, status);
enum elf_type
{
ELF_TYPE_EXEC,
ELF_TYPE_PI_EXEC,
ELF_TYPE_DSO,
ELF_TYPE_RELOCATABLE,
ELF_TYPE_UNKNOWN

192
src/abg-dwarf-reader.cc
View File

@ -1870,18 +1870,111 @@ lookup_public_variable_symbol_from_elf(const environment* env,
return found;
}
/// Get data tag information of an ELF file by looking up into its
/// dynamic segment
///
/// @param elf the elf handle to use for the query.
///
/// @param dt_tag data tag to look for in dynamic segment
/// @param dt_tag_data vector of found information for a given @p data_tag
///
/// @return true iff data tag @p data_tag was found
bool
lookup_data_tag_from_dynamic_segment(Elf* elf,
Elf64_Sxword data_tag,
vector<string>& dt_tag_data)
{
size_t num_prog_headers = 0;
bool found = false;
if (elf_getphdrnum(elf, &num_prog_headers) < 0)
return found;
// Cycle through each program header.
for (size_t i = 0; i < num_prog_headers; ++i)
{
GElf_Phdr phdr_mem;
GElf_Phdr *phdr = gelf_getphdr(elf, i, &phdr_mem);
if (phdr == NULL || phdr->p_type != PT_DYNAMIC)
continue;
// Poke at the dynamic segment like a section, so that we can
// get its section header information; also we'd like to read
// the data of the segment by using elf_getdata() but that
// function needs a Elf_Scn data structure to act on.
// Elfutils doesn't really have any particular function to
// access segment data, other than the functions used to
// access section data.
Elf_Scn *dynamic_section = gelf_offscn(elf, phdr->p_offset);
GElf_Shdr shdr_mem;
GElf_Shdr *dynamic_section_header = gelf_getshdr(dynamic_section,
&shdr_mem);
if (dynamic_section_header == NULL
|| dynamic_section_header->sh_type != SHT_DYNAMIC)
continue;
// Get data of the dynamic segment (seen as a section).
Elf_Data *data = elf_getdata(dynamic_section, NULL);
if (data == NULL)
continue;
// Get the index of the section headers string table.
size_t string_table_index = 0;
assert (elf_getshdrstrndx(elf, &string_table_index) >= 0);
size_t dynamic_section_header_entry_size = gelf_fsize(elf,
ELF_T_DYN, 1,
EV_CURRENT);
GElf_Shdr link_mem;
GElf_Shdr *link =
gelf_getshdr(elf_getscn(elf,
dynamic_section_header->sh_link),
&link_mem);
assert(link != NULL);
size_t num_dynamic_section_entries =
dynamic_section_header->sh_size / dynamic_section_header_entry_size;
// Now walk through all the DT_* data tags that are in the
// segment/section
for (size_t j = 0; j < num_dynamic_section_entries; ++j)
{
GElf_Dyn dynamic_section_mem;
GElf_Dyn *dynamic_section = gelf_getdyn(data,
j,
&dynamic_section_mem);
if (dynamic_section->d_tag == data_tag)
{
dt_tag_data.push_back(elf_strptr(elf,
dynamic_section_header->sh_link,
dynamic_section->d_un.d_val));
found = true;
}
}
}
return found;
}
/// Convert the type of ELF file into @ref elf_type.
///
/// @param header a elf header to get the ELF file type from.
/// @param elf the elf handle to use for the query.
///
/// @return the @ref elf_type for a given elf type.
static elf_type
elf_file_type(const GElf_Ehdr* header)
elf_file_type(Elf* elf)
{
GElf_Ehdr ehdr_mem;
GElf_Ehdr *header = gelf_getehdr (elf, &ehdr_mem);
vector<string> dt_debug_data;
switch (header->e_type)
{
case ET_DYN:
return ELF_TYPE_DSO;
if (lookup_data_tag_from_dynamic_segment(elf, DT_DEBUG, dt_debug_data))
return ELF_TYPE_PI_EXEC;
else
return ELF_TYPE_DSO;
case ET_EXEC:
return ELF_TYPE_EXEC;
case ET_REL:
@ -3113,10 +3206,7 @@ public:
elf_type
get_elf_file_type()
{
Elf* elf = elf_handle();
GElf_Ehdr eh_mem;
GElf_Ehdr* elf_header = gelf_getehdr(elf, &eh_mem);
return elf_file_type(elf_header);
return elf_file_type(elf_handle());
}
/// The section containing the symbol table from the current ELF
@ -4087,88 +4177,15 @@ public:
/// Load the DT_NEEDED and DT_SONAME elf TAGS.
///
/// @return true if the tags could be read, false otherwise.
void
load_dt_soname_and_needed()
{
size_t num_prog_headers = 0;
if (elf_getphdrnum(elf_handle(), &num_prog_headers) < 0)
return;
lookup_data_tag_from_dynamic_segment(elf_handle(), DT_NEEDED, dt_needed_);
unsigned found = 0;
// Cycle through each program header.
for (size_t i = 0; i < num_prog_headers; ++i)
{
GElf_Phdr phdr_mem;
GElf_Phdr *phdr = gelf_getphdr(elf_handle(), i, &phdr_mem);
if (phdr == NULL || phdr->p_type != PT_DYNAMIC)
continue;
// Poke at the dynamic segment like a section, so that we can
// get its section header information; also we'd like to read
// the data of the segment by using elf_getdata() but that
// function needs a Elf_Scn data structure to act on.
// Elfutils doesn't really have any particular function to
// access segment data, other than the functions used to
// access section data.
Elf_Scn *dynamic_section = gelf_offscn(elf_handle(), phdr->p_offset);
GElf_Shdr shdr_mem;
GElf_Shdr *dynamic_section_header = gelf_getshdr(dynamic_section,
&shdr_mem);
if (dynamic_section_header == NULL
|| dynamic_section_header->sh_type != SHT_DYNAMIC)
continue;
// Get data of the dynamic segment (seen a a section).
Elf_Data *data = elf_getdata(dynamic_section, NULL);
if (data == NULL)
continue;
// Get the index of the section headers string table.
size_t string_table_index = 0;
assert (elf_getshdrstrndx(elf_handle(), &string_table_index) >= 0);
size_t dynamic_section_header_entry_size = gelf_fsize(elf_handle(),
ELF_T_DYN, 1,
EV_CURRENT);
GElf_Shdr link_mem;
GElf_Shdr *link =
gelf_getshdr(elf_getscn(elf_handle(),
dynamic_section_header->sh_link),
&link_mem);
assert(link != NULL);
size_t num_dynamic_section_entries =
dynamic_section_header->sh_size / dynamic_section_header_entry_size;
// Now walk through all the DT_* data tags that are in the
// segment/section
for (size_t j = 0; j < num_dynamic_section_entries; ++j)
{
GElf_Dyn dynamic_section_mem;
GElf_Dyn *dynamic_section = gelf_getdyn(data,
j,
&dynamic_section_mem);
if (dynamic_section == NULL)
break;
if (dynamic_section->d_tag == DT_NEEDED)
{
string dt_needed = elf_strptr(elf_handle(),
dynamic_section_header->sh_link,
dynamic_section->d_un.d_val);
dt_needed_.push_back(dt_needed);
++found;
}
else if (dynamic_section->d_tag == DT_SONAME)
{
dt_soname_ = elf_strptr(elf_handle(),
dynamic_section_header->sh_link,
dynamic_section->d_un.d_val);
}
}
}
vector<string> dt_tag_data;
lookup_data_tag_from_dynamic_segment(elf_handle(), DT_SONAME, dt_tag_data);
if (!dt_tag_data.empty())
dt_soname_ = dt_tag_data[0];
}
/// Read the string representing the architecture of the current ELF
@ -9773,10 +9790,7 @@ get_type_of_elf_file(const string& path, elf_type& type)
elf_version (EV_CURRENT);
Elf *elf = elf_begin (fd, ELF_C_READ_MMAP, NULL);
GElf_Ehdr ehdr_mem;
GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
string soname;
type = elf_file_type(ehdr);
type = elf_file_type(elf);
close(fd);
return true;

5
tests/data/Makefile.am
View File

@ -1090,5 +1090,8 @@ test-diff-pkg/gtk2-debuginfo-2.24.22-5.el7.i686.rpm \
test-diff-pkg/gtk2-debuginfo-2.24.28-8.el7.i686.rpm \
test-diff-pkg/gtk2-immodule-xim-2.24.22-5.el7.i686--gtk2-immodule-xim-2.24.28-8.el7.i686-report-0.txt \
test-diff-pkg/gtk2-immodule-xim-2.24.22-5.el7.i686.rpm \
test-diff-pkg/gtk2-immodule-xim-2.24.28-8.el7.i686.rpm
test-diff-pkg/gtk2-immodule-xim-2.24.28-8.el7.i686.rpm \
test-diff-pkg/tarpkg-1-dir1.tar.gz \
test-diff-pkg/tarpkg-1-dir2.tar.gz \
test-diff-pkg/tarpkg-1-report-0.txt

BIN
tests/data/test-diff-pkg/tarpkg-1-dir1.tar.gz Normal file
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Binary file not shown.

BIN
tests/data/test-diff-pkg/tarpkg-1-dir2.tar.gz Normal file
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Binary file not shown.

16
tests/data/test-diff-pkg/tarpkg-1-report-0.txt Normal file
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@ -0,0 +1,16 @@
================ changes of 'libobj-v0.so'===============
Functions changes summary: 0 Removed, 1 Changed, 0 Added function
Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
1 function with some indirect sub-type change:
[C]'function void bar(S&)' at obj-v0.cc:16:1 has some indirect sub-type changes:
parameter 1 of type 'S&' has sub-type changes:
in referenced type 'struct S' at obj-v0.cc:4:1:
type size changed from 32 to 64 bits
1 data member insertion:
'char S::mem1', at offset 32 (in bits) at obj-v0.cc:7:1
================ end of changes of 'libobj-v0.so'===============

10
tests/test-diff-pkg.cc
View File

@ -195,6 +195,16 @@ static InOutSpec in_out_specs[] =
"data/test-diff-pkg/tarpkg-0-report-0.txt",
"output/test-diff-pkg/tarpkg-0-report-03.txt"
},
{
"data/test-diff-pkg/tarpkg-1-dir1.tar.gz",
"data/test-diff-pkg/tarpkg-1-dir2.tar.gz",
"--dso-only",
"",
"",
"",
"data/test-diff-pkg/tarpkg-1-report-0.txt",
"output/test-diff-pkg/tarpkg-1-report-0.txt"
},
#endif //WITH_TAR
#ifdef WITH_RPM

9
tools/abipkgdiff.cc
View File

@ -1164,7 +1164,8 @@ create_maps_of_package_content(package& package,
else
{
if (e->type != abigail::dwarf_reader::ELF_TYPE_DSO
&& e->type != abigail::dwarf_reader::ELF_TYPE_EXEC)
&& e->type != abigail::dwarf_reader::ELF_TYPE_EXEC
&& e->type != abigail::dwarf_reader::ELF_TYPE_PI_EXEC)
{
if (verbose)
emit_prefix("abipkgdiff", cerr)
@ -1404,7 +1405,8 @@ compare(package& first_package,
if (iter != second_package.path_elf_file_sptr_map().end()
&& (iter->second->type == abigail::dwarf_reader::ELF_TYPE_DSO
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_EXEC))
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_EXEC
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_PI_EXEC))
{
elf_pairs.push_back(compare_args_sptr(new compare_args(*it->second,
debug_dir1, *iter->second,
@ -1456,7 +1458,8 @@ compare(package& first_package,
if (iter != second_package.path_elf_file_sptr_map().end()
&& (iter->second->type == abigail::dwarf_reader::ELF_TYPE_DSO
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_EXEC))
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_EXEC
|| iter->second->type == abigail::dwarf_reader::ELF_TYPE_PI_EXEC))
{
second_package.path_elf_file_sptr_map().erase(iter);
while (true)