Hi, This series adds support for the ARMv8.3 pointer authentication extension, enabling userspace return address protection with GCC 7 and above. (The previous version also had in-kernel pointer authentication patches as RFC; these will be updated and sent at a later time.) Changes since v5 [1]: - Exposed all 5 keys (not just APIAKey) [Will] - New prctl for reinitializing keys [Will] - New ptrace options for getting and setting keys [Will] - Keys now per-thread instead of per-mm [Catalin] - Fixed cpufeature detection for late CPUs [Suzuki] - Added comments for ESR_ELx_EC_* definitions [Will] - Rebased onto v4.20-rc5 This series is based on v4.20-rc5. The aarch64 bootwrapper [2] does the necessary EL3 setup. The patches are also available at: git://linux-arm.org/linux-km.git ptrauth-user Extension Overview ================== The ARMv8.3 pointer authentication extension adds functionality to detect modification of pointer values, mitigating certain classes of attack such as stack smashing, and making return oriented programming attacks harder. The extension introduces the concept of a pointer authentication code (PAC), which is stored in some upper bits of pointers. Each PAC is derived from the original pointer, another 64-bit value (e.g. the stack pointer), and a secret 128-bit key. New instructions are added which can be used to: * Insert a PAC into a pointer * Strip a PAC from a pointer * Authenticate strip a PAC from a pointer If authentication succeeds, the code is removed, yielding the original pointer. If authentication fails, bits are set in the pointer such that it is guaranteed to cause a fault if used. These instructions can make use of four keys: * APIAKey (A.K.A. Instruction A key) * APIBKey (A.K.A. Instruction B key) * APDAKey (A.K.A. Data A key) * APDBKey (A.K.A. Data B Key) A subset of these instruction encodings have been allocated from the HINT space, and will operate as NOPs on any ARMv8-A parts which do not feature the extension (or if purposefully disabled by the kernel). Software using only this subset of the instructions should function correctly on all ARMv8-A parts. Additionally, instructions are added to authenticate small blocks of memory in similar fashion, using APGAKey (A.K.A. Generic key). This series =========== This series enables userspace to use any pointer authentication instructions, using any of the 5 keys. The keys are initialised and maintained per-process (shared by all threads). For the time being, this series hides pointer authentication functionality from KVM guests. Amit Kachhap is currently looking into supporting pointer authentication in guests. Setting uprobes on pointer authentication instructions is not yet supported, and may cause the application to behave in unexpected ways. Feedback and comments are welcome. Thanks, Kristina [1] https://lore.kernel.org/lkml/20181005084754.20950-1-kristina.martsenko@xxxxxxx/ [2] git://git.kernel.org/pub/scm/linux/kernel/git/mark/boot-wrapper-aarch64.git Kristina Martsenko (3): arm64: add comments about EC exception levels arm64: add prctl control for resetting ptrauth keys arm64: add ptrace regsets for ptrauth key management Mark Rutland (10): arm64: add pointer authentication register bits arm64/kvm: consistently handle host HCR_EL2 flags arm64/kvm: hide ptrauth from guests arm64: Don't trap host pointer auth use to EL2 arm64/cpufeature: detect pointer authentication arm64: add basic pointer authentication support arm64: expose user PAC bit positions via ptrace arm64: perf: strip PAC when unwinding userspace arm64: enable pointer authentication arm64: docs: document pointer authentication Documentation/arm64/booting.txt | 8 ++ Documentation/arm64/cpu-feature-registers.txt | 8 ++ Documentation/arm64/elf_hwcaps.txt | 12 +++ Documentation/arm64/pointer-authentication.txt | 93 +++++++++++++++++++++ arch/arm64/Kconfig | 23 ++++++ arch/arm64/include/asm/cpucaps.h | 8 +- arch/arm64/include/asm/cpufeature.h | 12 +++ arch/arm64/include/asm/esr.h | 17 ++-- arch/arm64/include/asm/kvm_arm.h | 3 + arch/arm64/include/asm/pointer_auth.h | 93 +++++++++++++++++++++ arch/arm64/include/asm/processor.h | 4 + arch/arm64/include/asm/sysreg.h | 30 +++++++ arch/arm64/include/asm/thread_info.h | 4 + arch/arm64/include/uapi/asm/hwcap.h | 2 + arch/arm64/include/uapi/asm/ptrace.h | 25 ++++++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/cpufeature.c | 103 +++++++++++++++++++++++ arch/arm64/kernel/cpuinfo.c | 2 + arch/arm64/kernel/head.S | 5 +- arch/arm64/kernel/perf_callchain.c | 6 +- arch/arm64/kernel/pointer_auth.c | 47 +++++++++++ arch/arm64/kernel/process.c | 4 + arch/arm64/kernel/ptrace.c | 110 +++++++++++++++++++++++++ arch/arm64/kvm/handle_exit.c | 18 ++++ arch/arm64/kvm/hyp/switch.c | 2 +- arch/arm64/kvm/sys_regs.c | 8 ++ include/uapi/linux/elf.h | 3 + include/uapi/linux/prctl.h | 8 ++ kernel/sys.c | 8 ++ 29 files changed, 653 insertions(+), 14 deletions(-) create mode 100644 Documentation/arm64/pointer-authentication.txt create mode 100644 arch/arm64/include/asm/pointer_auth.h create mode 100644 arch/arm64/kernel/pointer_auth.c -- 2.11.0 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
