Control-flow Enforcement (CET) is a new Intel processor feature that blocks
return/jump-oriented programming attacks. Details are in "Intel 64 and
IA-32 Architectures Software Developer's Manual" [1].
CET can protect applications and the kernel. This series enables only
application-level protection, and has three parts:
- Shadow stack [2],
- Indirect branch tracking [3], and
- Selftests [4].
I have run tests on these patches for quite some time, and they have been
very stable. Linux distributions with CET are available now, and Intel
processors with CET are already on the market. It would be nice if CET
support can be accepted into the kernel. I will be working to address any
issues should they come up.
Changes in v26:
- Patch #19: Instead of passing vm_flags, pass vma pointer to can_follow_*().
- Patch #29: Instead of passing vma is anonymous, pass vma pointer to
arch_validate_flags().
- Patch #30: Change PROT_SHSTK to PROT_SHADOW_STACK, remove redundant
VM_SHARED check.
- Rebase to Linus tree v5.12.
Changes in v25:
- Remove Kconfig X86_CET and software-defined feature flag X86_FEATURE_CET.
Use X86_SHADOW_STACK and X86_FEATURE_SHSTK directly. Update related
areas accordingly.
- Patch #16: Make same changes to do_huge_pmd_numa_page() as to
do_numa_page().
- Patch #25: Update signal handling, use restorer address already
retrieved, update MSR restoring code.
- Smaller changes are called out in each patch.
- Rebase to Linus tree v5.12-rc7.
[1] Intel 64 and IA-32 Architectures Software Developer's Manual:
https://software.intel.com/en-us/download/intel-64-and-ia-32-
architectures-sdm-combined-volumes-1-2a-2b-2c-2d-3a-3b-3c-3d-and-4
[2] Shadow Stack patches v25:
https://lore.kernel.org/r/20210415221419.31835-1-yu-cheng.yu@xxxxxxxxx/
[3] Indirect Branch Tracking patches v25
https://lore.kernel.org/r/20210415221734.32628-1-yu-cheng.yu@xxxxxxxxx/
[4] I am holding off the selftests changes and working to get Reviewed-by's.
The earlier version of the selftests patches:
https://lkml.kernel.org/r/20200521211720.20236-1-yu-cheng.yu@xxxxxxxxx/
[5] The kernel ptrace patch is tested with an Intel-internal updated GDB.
I am holding off the kernel ptrace patch to re-test it with my earlier
patch for fixing regset holes.
Yu-cheng Yu (30):
Documentation/x86: Add CET description
x86/cet/shstk: Add Kconfig option for Shadow Stack
x86/cpufeatures: Add CET CPU feature flags for Control-flow
Enforcement Technology (CET)
x86/cpufeatures: Introduce CPU setup and option parsing for CET
x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states
x86/cet: Add control-protection fault handler
x86/mm: Remove _PAGE_DIRTY from kernel RO pages
x86/mm: Move pmd_write(), pud_write() up in the file
x86/mm: Introduce _PAGE_COW
drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS
x86/mm: Update pte_modify for _PAGE_COW
x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for
transition from _PAGE_DIRTY to _PAGE_COW
mm: Introduce VM_SHADOW_STACK for shadow stack memory
x86/mm: Shadow Stack page fault error checking
x86/mm: Update maybe_mkwrite() for shadow stack
mm: Fixup places that call pte_mkwrite() directly
mm: Add guard pages around a shadow stack.
mm/mmap: Add shadow stack pages to memory accounting
mm: Update can_follow_write_pte() for shadow stack
mm/mprotect: Exclude shadow stack from preserve_write
mm: Re-introduce vm_flags to do_mmap()
x86/cet/shstk: Add user-mode shadow stack support
x86/cet/shstk: Handle thread shadow stack
x86/cet/shstk: Introduce shadow stack token setup/verify routines
x86/cet/shstk: Handle signals for shadow stack
ELF: Introduce arch_setup_elf_property()
x86/cet/shstk: Add arch_prctl functions for shadow stack
mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h
mm: Update arch_validate_flags() to include vma anonymous
mm: Introduce PROT_SHADOW_STACK for shadow stack
.../admin-guide/kernel-parameters.txt | 6 +
Documentation/filesystems/proc.rst | 1 +
Documentation/x86/index.rst | 1 +
Documentation/x86/intel_cet.rst | 136 ++++++++
arch/arm64/include/asm/elf.h | 5 +
arch/arm64/include/asm/mman.h | 4 +-
arch/sparc/include/asm/mman.h | 4 +-
arch/x86/Kconfig | 24 ++
arch/x86/Kconfig.assembler | 5 +
arch/x86/ia32/ia32_signal.c | 24 +-
arch/x86/include/asm/cet.h | 52 +++
arch/x86/include/asm/cpufeatures.h | 2 +
arch/x86/include/asm/disabled-features.h | 8 +-
arch/x86/include/asm/elf.h | 13 +
arch/x86/include/asm/fpu/internal.h | 2 +
arch/x86/include/asm/fpu/types.h | 23 +-
arch/x86/include/asm/fpu/xstate.h | 6 +-
arch/x86/include/asm/idtentry.h | 4 +
arch/x86/include/asm/mman.h | 88 +++++
arch/x86/include/asm/mmu_context.h | 3 +
arch/x86/include/asm/msr-index.h | 19 ++
arch/x86/include/asm/page_types.h | 7 +
arch/x86/include/asm/pgtable.h | 299 +++++++++++++++--
arch/x86/include/asm/pgtable_types.h | 48 ++-
arch/x86/include/asm/processor.h | 5 +
arch/x86/include/asm/special_insns.h | 32 ++
arch/x86/include/asm/trap_pf.h | 2 +
arch/x86/include/uapi/asm/mman.h | 28 +-
arch/x86/include/uapi/asm/prctl.h | 4 +
arch/x86/include/uapi/asm/processor-flags.h | 2 +
arch/x86/include/uapi/asm/sigcontext.h | 9 +
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/cet_prctl.c | 60 ++++
arch/x86/kernel/cpu/common.c | 14 +
arch/x86/kernel/cpu/cpuid-deps.c | 2 +
arch/x86/kernel/fpu/signal.c | 137 +++++++-
arch/x86/kernel/fpu/xstate.c | 10 +-
arch/x86/kernel/idt.c | 4 +
arch/x86/kernel/process.c | 21 +-
arch/x86/kernel/process_64.c | 32 ++
arch/x86/kernel/shstk.c | 304 ++++++++++++++++++
arch/x86/kernel/signal.c | 9 +
arch/x86/kernel/signal_compat.c | 2 +-
arch/x86/kernel/traps.c | 63 ++++
arch/x86/mm/fault.c | 19 ++
arch/x86/mm/mmap.c | 48 +++
arch/x86/mm/pat/set_memory.c | 2 +-
arch/x86/mm/pgtable.c | 25 ++
drivers/gpu/drm/i915/gvt/gtt.c | 2 +-
fs/aio.c | 2 +-
fs/binfmt_elf.c | 4 +
fs/proc/task_mmu.c | 3 +
include/linux/elf.h | 6 +
include/linux/mm.h | 18 +-
include/linux/mman.h | 2 +-
include/linux/pgtable.h | 7 +
include/uapi/asm-generic/siginfo.h | 3 +-
include/uapi/linux/elf.h | 9 +
ipc/shm.c | 2 +-
mm/gup.c | 16 +-
mm/huge_memory.c | 27 +-
mm/memory.c | 5 +-
mm/migrate.c | 3 +-
mm/mmap.c | 17 +-
mm/mprotect.c | 11 +-
mm/nommu.c | 4 +-
mm/util.c | 2 +-
67 files changed, 1644 insertions(+), 119 deletions(-)
create mode 100644 Documentation/x86/intel_cet.rst
create mode 100644 arch/x86/include/asm/cet.h
create mode 100644 arch/x86/include/asm/mman.h
create mode 100644 arch/x86/kernel/cet_prctl.c
create mode 100644 arch/x86/kernel/shstk.c
--
2.21.0
