[arch-projects] [devtools] [PATCH] enforce hardening flags and use PIE on x86_64

[Daniel Micay]

On 23/07/14 05:21 PM, Thomas Bächler wrote:
> Am 23.07.2014 22:17, schrieb Daniel Micay:
>> PIE is required for full address space layout optimization (ASLR) and
>> there is little to no benefit from ASLR without it since global ELF
>> tables (GOT/PLT) and application code are at known locations.
>>
>> A wrapper script is required in order to pass the correct flags for
>> executables without changing the flags for libraries. It adds `-pie`
>> when linking (no `-c` switch) if `-static` or `-shared` are not passed,
>> and `-fPIE` whenever `-fPIC` is not already there. This technique comes
>> from the Debian hardening wrappers.
>>
>> Position independent code is expensive on i686, so it's only enabled by
>> default on x86_64 where the cost is negligible. It can be enabled on a
>> package-by-package basis on i686. The same cost already exists for any
>> code in a dynamic library.
>>
>> The hardening-wrapper package also enforces the chosen hardening flags
>> even when build systems aren't using CFLAGS / CXXFLAGS / LDFLAGS from
>> the environment. It would need to be moved from [community] to [core].
> 
> Why should this be in devtools? The build settings are configured in
> makepkg and we should not split this into two places.

I went ahead and altered the hardening-wrapper script so that it doesn't
require any devtools / makepkg modifications. It does add a new
/etc/hardening-wrapper.conf configuration file though... I don't really
want to encode the difference between i686 / x86_64 into the script
itself by installing a separate one on both architectures.

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