This series adds support for Clang's Control-Flow Integrity (CFI) checking. With CFI, the compiler injects a runtime check before each indirect function call to ensure the target is a valid function with the correct static type. This restricts possible call targets and makes it more difficult for an attacker to exploit bugs that allow the modification of stored function pointers. For more details, see: https://clang.llvm.org/docs/ControlFlowIntegrity.html The first patch contains build system changes and error handling, and implements support for cross-module indirect call checking. The remaining patches address issues caused by the compiler instrumentation. These include fixing known type mismatches, as well as issues with address space confusion and cross-module function address equality. These patches add support only for arm64, but I'll post patches also for x86_64 after we address the remaining issues there, including objtool support. You can also pull this series from https://github.com/samitolvanen/linux.git cfi-v2 --- Changes in v2: - Fixed .text merging in module.lds.S. - Added WARN_ON_FUNCTION_MISMATCH() and changed kernel/thread.c and kernel/workqueue.c to use the macro instead. Sami Tolvanen (17): add support for Clang CFI cfi: add __cficanonical mm: add generic __va_function and __pa_function macros module: ensure __cfi_check alignment workqueue: use WARN_ON_FUNCTION_MISMATCH kthread: use WARN_ON_FUNCTION_MISMATCH kallsyms: strip ThinLTO hashes from static functions bpf: disable CFI in dispatcher functions lib/list_sort: fix function type mismatches lkdtm: use __va_function psci: use __pa_function for cpu_resume arm64: implement __va_function arm64: use __pa_function arm64: add __nocfi to functions that jump to a physical address arm64: add __nocfi to __apply_alternatives KVM: arm64: Disable CFI for nVHE arm64: allow CONFIG_CFI_CLANG to be selected Makefile | 17 ++ arch/Kconfig | 45 +++ arch/arm64/Kconfig | 1 + arch/arm64/include/asm/memory.h | 15 + arch/arm64/include/asm/mmu_context.h | 4 +- arch/arm64/kernel/acpi_parking_protocol.c | 2 +- arch/arm64/kernel/alternative.c | 4 +- arch/arm64/kernel/cpu-reset.h | 10 +- arch/arm64/kernel/cpufeature.c | 4 +- arch/arm64/kernel/psci.c | 3 +- arch/arm64/kernel/smp_spin_table.c | 2 +- arch/arm64/kvm/hyp/nvhe/Makefile | 6 +- drivers/firmware/psci/psci.c | 4 +- drivers/misc/lkdtm/usercopy.c | 2 +- include/asm-generic/bug.h | 16 ++ include/asm-generic/vmlinux.lds.h | 20 +- include/linux/bpf.h | 4 +- include/linux/cfi.h | 41 +++ include/linux/compiler-clang.h | 3 + include/linux/compiler_types.h | 8 + include/linux/init.h | 6 +- include/linux/mm.h | 8 + include/linux/module.h | 13 +- include/linux/pci.h | 4 +- init/Kconfig | 2 +- kernel/Makefile | 4 + kernel/cfi.c | 329 ++++++++++++++++++++++ kernel/kallsyms.c | 54 +++- kernel/kthread.c | 3 +- kernel/module.c | 43 +++ kernel/workqueue.c | 2 +- lib/list_sort.c | 8 +- scripts/Makefile.modfinal | 2 +- scripts/module.lds.S | 18 +- 34 files changed, 663 insertions(+), 44 deletions(-) create mode 100644 include/linux/cfi.h create mode 100644 kernel/cfi.c base-commit: 6417f03132a6952cd17ddd8eaddbac92b61b17e0 -- 2.31.0.291.g576ba9dcdaf-goog
