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-v5 --- Changes in v5: - Changed module.lds.S to only include <asm/page.h> when CFI is enabled to fix the MIPS build. - Added a patch that fixes dynamic ftrace with CFI on arm64. Changes in v4: - Per Mark's suggestion, dropped __pa_function() and renamed __va_function() to function_nocfi(). - Added a comment to function_nocfi() to explain what it does. - Updated the psci patch to use an intermediate variable for the physical address for clarity. Changes in v3: - Added a patch to change list_sort() callers treewide to use const pointers instead of simply removing the internal casts. - Changed cleanup_symbol_name() to return bool. - Changed module.lds.S to drop the .eh_frame section only with CONFIG_CFI_CLANG. - Switched to synchronize_rcu() in update_shadow(). 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 (18): add support for Clang CFI cfi: add __cficanonical mm: add generic function_nocfi macro 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 treewide: Change list_sort to use const pointers lkdtm: use function_nocfi psci: use function_nocfi for cpu_resume arm64: implement function_nocfi arm64: use function_nocfi with __pa_symbol arm64: add __nocfi to functions that jump to a physical address arm64: add __nocfi to __apply_alternatives arm64: ftrace: use function_nocfi for ftrace_call 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 | 3 +- arch/arm64/kernel/alternative.c | 4 +- arch/arm64/kernel/cpu-reset.h | 10 +- arch/arm64/kernel/cpufeature.c | 4 +- arch/arm64/kernel/ftrace.c | 2 +- arch/arm64/kernel/psci.c | 3 +- arch/arm64/kernel/smp_spin_table.c | 3 +- arch/arm64/kvm/hyp/nvhe/Makefile | 6 +- arch/arm64/kvm/vgic/vgic-its.c | 8 +- arch/arm64/kvm/vgic/vgic.c | 3 +- block/blk-mq-sched.c | 3 +- block/blk-mq.c | 3 +- drivers/acpi/nfit/core.c | 3 +- drivers/acpi/numa/hmat.c | 3 +- drivers/clk/keystone/sci-clk.c | 4 +- drivers/firmware/psci/psci.c | 7 +- drivers/gpu/drm/drm_modes.c | 3 +- drivers/gpu/drm/i915/gt/intel_engine_user.c | 3 +- drivers/gpu/drm/i915/gvt/debugfs.c | 2 +- drivers/gpu/drm/i915/selftests/i915_gem_gtt.c | 3 +- drivers/gpu/drm/radeon/radeon_cs.c | 4 +- .../hw/usnic/usnic_uiom_interval_tree.c | 3 +- drivers/interconnect/qcom/bcm-voter.c | 2 +- drivers/md/raid5.c | 3 +- drivers/misc/lkdtm/usercopy.c | 2 +- drivers/misc/sram.c | 4 +- drivers/nvme/host/core.c | 3 +- .../controller/cadence/pcie-cadence-host.c | 3 +- drivers/spi/spi-loopback-test.c | 3 +- fs/btrfs/raid56.c | 3 +- fs/btrfs/tree-log.c | 3 +- fs/btrfs/volumes.c | 3 +- fs/ext4/fsmap.c | 4 +- fs/gfs2/glock.c | 3 +- fs/gfs2/log.c | 2 +- fs/gfs2/lops.c | 3 +- fs/iomap/buffered-io.c | 3 +- fs/ubifs/gc.c | 7 +- fs/ubifs/replay.c | 4 +- fs/xfs/scrub/bitmap.c | 4 +- fs/xfs/xfs_bmap_item.c | 4 +- fs/xfs/xfs_buf.c | 6 +- fs/xfs/xfs_extent_busy.c | 4 +- fs/xfs/xfs_extent_busy.h | 3 +- fs/xfs/xfs_extfree_item.c | 4 +- fs/xfs/xfs_refcount_item.c | 4 +- fs/xfs/xfs_rmap_item.c | 4 +- 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/list_sort.h | 7 +- include/linux/mm.h | 10 + include/linux/module.h | 13 +- include/linux/pci.h | 4 +- init/Kconfig | 2 +- kernel/Makefile | 4 + kernel/cfi.c | 329 ++++++++++++++++++ kernel/kallsyms.c | 55 ++- kernel/kthread.c | 3 +- kernel/module.c | 43 +++ kernel/workqueue.c | 2 +- lib/list_sort.c | 17 +- lib/test_list_sort.c | 3 +- net/tipc/name_table.c | 4 +- scripts/Makefile.modfinal | 2 +- scripts/module.lds.S | 19 +- 75 files changed, 759 insertions(+), 113 deletions(-) create mode 100644 include/linux/cfi.h create mode 100644 kernel/cfi.c base-commit: 6905b1dc3c32a094f0da61bd656a740f0a97d592 -- 2.31.0.208.g409f899ff0-goog
