On Thu, Aug 01, 2024 at 01:06:29PM +0100, Mark Brown wrote: > Three architectures (x86, aarch64, riscv) have announced support for > shadow stacks with fairly similar functionality. While x86 is using > arch_prctl() to control the functionality neither arm64 nor riscv uses > that interface so this patch adds arch-agnostic prctl() support to > get and set status of shadow stacks and lock the current configuation to > prevent further changes, with support for turning on and off individual > subfeatures so applications can limit their exposure to features that > they do not need. The features are: > > - PR_SHADOW_STACK_ENABLE: Tracking and enforcement of shadow stacks, > including allocation of a shadow stack if one is not already > allocated. > - PR_SHADOW_STACK_WRITE: Writes to specific addresses in the shadow > stack. > - PR_SHADOW_STACK_PUSH: Push additional values onto the shadow stack. > > These features are expected to be inherited by new threads and cleared > on exec(), unknown features should be rejected for enable but accepted > for locking (in order to allow for future proofing). > > This is based on a patch originally written by Deepak Gupta but modified > fairly heavily, support for indirect landing pads is removed, additional > modes added and the locking interface reworked. The set status prctl() > is also reworked to just set flags, if setting/reading the shadow stack > pointer is required this could be a separate prctl. > > Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@xxxxxxxxxx> > Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
