On Thu, Apr 01, 2021 at 04:31:58PM -0700, Sami Tolvanen wrote: > 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 > Hi Sami, I booted this series on Equinix's c1.large.arm (2x Cavium ThunderX CN8890) and c2.large.arm (1x Ampere eMAG 8180) servers [1] and my Raspberry Pi 4B. I ran them through LTP's read_all test case on both /proc and /sys and a few compile workloads, only uncovering one issue [2]. Consider this series: Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> [1]: https://metal.equinix.com/developers/docs/servers/ [2]: https://lore.kernel.org/r/20210402195241.gahc5w25gezluw7p@archlinux-ax161/ Cheers, Nathan
