Re: [CFT] ASLR and PIE on amd64

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.

>
> Shawn Webb
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