Re: same prog, different sizes

On Mon, Sep 22, 2014 at 2:12 AM, Bela Lubkin <[email protected]> wrote:
> Jorge Almeida and Steven Honeyman wrote:
>
> Steven>>> On your Gentoo i3... am I right in thinking you have a hardened=
/PaX
> Steven>>> build environment?
>
> Jorge>> Nope. It's a standard profile, no fancy
> Jorge>> stuff whatsoever (box is used to backups and compiling some stuff=
,
> Jorge>> used mainly via ssh, not even X installed)
>
> Steven> Oh well, worth a guess! I just noticed this strange program heade=
r
> Steven> entry (only in the i3 version), which google says has something t=
o do
> Steven> with PaX. They are both the same binary really, but the i3 has a =
few
> Steven> kb of padding on the end (just empty space). I have no idea why; =
but
> Steven> I'm sure someone will be able to help you.
>
> I think Steven's right.  For instance, see:
>
>    https://blogs.gentoo.org/mgorny/2014/06/23/inlining-marchnative-for-di=
stcc/
>
> which says (about flags being bandied about by `gcc`):
>
> " You may also notice -fstack-protector there. This is because nowadays
> " Gentoo enables it by default.
>
> -- the 2nd sentence links to:
>
>    http://sources.gentoo.org/gitweb/?p=3Dproj/gentoo-news.git;a=3Dblob;f=
=3D2014/2014-06-15-gcc48_ssp/2014-06-15-gcc48_ssp.en.txt
>
> which certainly seems to support the claim.

This looked promising. I tried it with -fno-stack-protector, but there
is no difference. I also added -fno-pie, still no joy.

>
> The two binaries contain .comment sections with "GCC: (GNU) 4.8.2" and
> "GCC: (Gentoo 4.8.3 p1.1, pie-0.5.9) 4.8.3"; in which I *think* the
> "pie-0.5.9" is another hint about hardening.

$ eselect profile list
Available profile symlink targets:
  [1]   default/linux/x86/13.0 *
  [2]   default/linux/x86/13.0/selinux
  [3]   default/linux/x86/13.0/desktop
  [4]   default/linux/x86/13.0/desktop/gnome
  [5]   default/linux/x86/13.0/desktop/gnome/systemd
  [6]   default/linux/x86/13.0/desktop/kde
  [7]   default/linux/x86/13.0/desktop/kde/systemd
  [8]   default/linux/x86/13.0/developer
  [9]   hardened/linux/x86
  [10]  hardened/linux/x86/selinux
  [11]  hardened/linux/musl/x86
  [12]  default/linux/uclibc/x86
  [13]  hardened/linux/uclibc/x86

Maybe some hardening features are somehow pulled when compiling with -stati=
c?

Just in case this contains some usefull info:

$ gcc -### -march=3Dnative -x c -
Using built-in specs.
COLLECT_GCC=3D/usr/i686-pc-linux-gnu/gcc-bin/4.8.3/gcc
COLLECT_LTO_WRAPPER=3D/usr/libexec/gcc/i686-pc-linux-gnu/4.8.3/lto-wrapper
Target: i686-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-4.8.3/work/gcc-4.8.3/configure
--host=3Di686-pc-linux-gnu --build=3Di686-pc-linux-gnu --prefix=3D/usr
--bindir=3D/usr/i686-pc-linux-gnu/gcc-bin/4.8.3
--includedir=3D/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/include
--datadir=3D/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3
--mandir=3D/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3/man
--infodir=3D/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3/info
--with-gxx-include-dir=3D/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/include/g++-v=
4
--with-python-dir=3D/share/gcc-data/i686-pc-linux-gnu/4.8.3/python
--enable-languages=3Dc,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --disable-nls
--enable-checking=3Drelease --with-bugurl=3Dhttps://bugs.gentoo.org/
--with-pkgversion=3D'Gentoo 4.8.3 p1.1, pie-0.5.9'
--enable-libstdcxx-time --enable-shared --enable-threads=3Dposix
--enable-__cxa_atexit --enable-clocale=3Dgnu --disable-multilib
--disable-altivec --disable-fixed-point --with-arch=3Di686
--enable-targets=3Dall --disable-libgcj --enable-libgomp
--disable-libmudflap --disable-libssp --enable-lto --without-cloog
Thread model: posix
gcc version 4.8.3 (Gentoo 4.8.3 p1.1, pie-0.5.9)
COLLECT_GCC_OPTIONS=3D'-march=3Dnative'
 /usr/libexec/gcc/i686-pc-linux-gnu/4.8.3/cc1 -quiet -
"-march=3Dcore-avx2" -mcx16 -msahf -mmovbe -maes -mpclmul -mpopcnt -mabm
-mno-lwp -mfma -mno-fma4 -mno-xop -mbmi -mbmi2 -mno-tbm -mavx -mavx2
-msse4.2 -msse4.1 -mlzcnt -mno-rtm -mno-hle -mrdrnd -mf16c -mfsgsbase
-mno-rdseed -mno-prfchw -mno-adx -mfxsr -mxsave -mxsaveopt --param
"l1-cache-size=3D32" --param "l1-cache-line-size=3D64" --param
"l2-cache-size=3D3072" "-mtune=3Dcore-avx2" -quiet -dumpbase - -auxbase -
-fstack-protector -o /tmp/ccxOOjI3.s
COLLECT_GCC_OPTIONS=3D'-march=3Dnative'
 /usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../i686-pc-linux-gnu/bin/as
--32 -o /tmp/ccm6d0Pe.o /tmp/ccxOOjI3.s
COMPILER_PATH=3D/usr/libexec/gcc/i686-pc-linux-gnu/4.8.3/:/usr/libexec/gcc/=
i686-pc-linux-gnu/4.8.3/:/usr/libexec/gcc/i686-pc-linux-gnu/:/usr/lib/gcc/i=
686-pc-linux-gnu/4.8.3/:/usr/lib/gcc/i686-pc-linux-gnu/:/usr/lib/gcc/i686-p=
c-linux-gnu/4.8.3/../../../../i686-pc-linux-gnu/bin/
LIBRARY_PATH=3D/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/:/usr/lib/gcc/i686-pc-l=
inux-gnu/4.8.3/../../../../i686-pc-linux-gnu/lib/../lib/:/usr/lib/gcc/i686-=
pc-linux-gnu/4.8.3/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/=
gcc/i686-pc-linux-gnu/4.8.3/../../../../i686-pc-linux-gnu/lib/:/usr/lib/gcc=
/i686-pc-linux-gnu/4.8.3/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS=3D'-march=3Dnative'
 /usr/libexec/gcc/i686-pc-linux-gnu/4.8.3/collect2 --eh-frame-hdr -m
elf_i386 -dynamic-linker /lib/ld-linux.so.2
/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../lib/crt1.o
/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../lib/crti.o
/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/crtbegin.o
-L/usr/lib/gcc/i686-pc-linux-gnu/4.8.3
-L/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../i686-pc-linux-gnu/lib/..=
/lib
-L/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../lib -L/lib/../lib
-L/usr/lib/../lib
-L/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../i686-pc-linux-gnu/lib
-L/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../.. /tmp/ccm6d0Pe.o -lgcc
--as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
--no-as-needed /usr/lib/gcc/i686-pc-linux-gnu/4.8.3/crtend.o
/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/../../../../lib/crtn.o

Thanks,

Jorge