[PATCH 00/17] Add support for Clang CFI

Sami Tolvanen
2021-03-12T00:50:17Z

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-v1

Sami Tolvanen (17):
add support for Clang CFI
cfi: add __cficanonical
mm: add generic __va_function and __pa_function macros
module: cfi: ensure __cfi_check alignment
workqueue: cfi: disable callback pointer check with modules
kthread: cfi: disable callback pointer check with modules
kallsyms: cfi: strip 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/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 | 8 +-
kernel/module.c | 43 +++
kernel/workqueue.c | 9 +-
lib/list_sort.c | 8 +-
scripts/Makefile.modfinal | 2 +-
scripts/module.lds.S | 14 +-
33 files changed, 655 insertions(+), 44 deletions(-)
create mode 100644 include/linux/cfi.h
create mode 100644 kernel/cfi.c

base-commit: 28806e4d9b97865b450d72156e9ad229f2067f0b
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2.31.0.rc2.261.g7f71774620-goog