Re: [CFT] ASLR and PIE on amd64

On 3/31/14, Shawn Webb <lattera_at_gmail.com> wrote:
> On Mar 31, 2014 02:07 AM +0200, Oliver Pinter wrote:
>> On 3/22/14, Shawn Webb <lattera_at_gmail.com> wrote:
>> > Hey All,
>> >
>> > First off, I hope that even as a non-committer, it's okay that I post
>> > a call for testing. If not, please excuse my newbishness in this
>> > process. This is my first time submitting a major patch upstream to
>> > FreeBSD.
>> >
>> > Over the past few months, I've had the opportunity and pleasure to
>> > enhance existing patches to FreeBSD that implement a common exploit
>> > mitigation technology called Address Space Layout Randomization (ASLR)
>> > along with support for Position Independent Executables (PIE).
>> > ASLR+PIE has been a long-requested feature by many people I've met on
>> > IRC.
>> >
>> > I've submitted my patch to PR kernel/181497. I'm currently in the
>> > process of adding PIE support to certain high-visibility applications
>> > in base (mainly network daemons). I've added a make.conf knob that's
>> > default to enabled (WITH_PIE=1). An application has to also explicitly
>> > support PIE as well by defining CAN_PIE in the Makefile prior to
>> > including bsd.prog.mk. After I get a decent amount of applications
>> > enabled with PIE support, I'll submit one last patch.
>> >
>> > The following sysctl's can be set with a kernel compiled with the
>> > PAX_ASLR option:
>> >
>> > security.pax.aslr.status: 1
>> > security.pax.aslr.debug: 0
>> > security.pax.aslr.mmap_len: 16
>> > security.pax.aslr.stack_len: 12
>> > security.pax.aslr.exec_len: 12
>> >
>> > The security.pax.aslr.status sysctl enables and disables the ASLR
>> > system as a whole. The debug sysctl gives debugging output. The
>> > mmap_len sysctl tells the ASLR system how many bits to randomize with
>> > mmap() is called. The stack_len sysctl tells the ASLR system how many
>> > bits to randomize in the stack. The exec_len sysctl tells the ASLR
>> > system how many bits to randomize the execbase (this controls PIE).
>> > These sysctls can be set as a per-jail basis. If you have an
>> > application which doesn't support ASLR, yet you want ASLR enabled for
>> > everything else, you can simply place that misbehaving application in
>> > a jail with only that jail's ASLR settings turned off.
>> >
>> > Please let me know how your testing goes. I'm giving a presentation at
>> > BSDCan regarding this.
>> >
>> > If you want to keep tabs on my bleeding-edge development process,
>> > please follow my progress on GitHub:
>> > https://github.com/lattera/freebsd (branch: soldierx/lattera/aslr).
>> >
>> > Thank you very much,
>>
>> Hi!
>>
>> Please apply this patch. This fixed an issue with tunables.
>
> Patch merged successfully into my GitHub repo. Fixed with commit
> d2c0813. I'll include it in my next patch submission upstream when I
> submit my PIE work. Thanks!

please see the attached patch, compile and boot tested on amd64

>