On 12/13/19 1:05 PM, Kees Cook wrote:
On Fri, Dec 13, 2019 at 10:40:54AM -0500, Stephen Smalley wrote:
See $(subject). If yes, there are some obvious candidates among the SELinux
data structures for randomized layouts to avoid fixed locations for
enforcing, initialized, etc. If not, then no point in pursuing it. Doesn't
look like Fedora enables it, probably because they'd have to publish the
random seeds anyway for third party kernel modules. But maybe it would be
useful for some distros/users? ChromeOS? Android?
It is used by "in-house" kernel builders who optimize for high security
above all other things (I've talked to a few of them over the years
when finding out what defenses they've wanted). I've also seen Huawai
Android patches that seem to indicate they're using it as well, but I
haven't been able to determine if any released devices are shipping with
it enabled. I've also had several people ask after the Clang randstruct
port, which is ongoing[1] by a couple people (added to CC).
I think it would be very handy to add some more markings to sensitive
data structures. Please send patches!
Do you know if there is something inhibiting usage in e.g. Pixel
devices? Performance impact?
-Kees
[1] https://reviews.llvm.org/D59254
https://github.com/da-x/llvm-project/commits/clang-r365631c-randstruct
https://github.com/da-x/linux/commits/android-4.19-randstruct
https://github.com/connorkuehl/llvm-project/commits/randstruct
https://github.com/connorkuehl/llvm-project/pull/21
