Messages in this thread | | | Date | Wed, 31 Aug 2022 15:04:20 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v4 00/21] KCFI support |
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On Tue, Aug 30, 2022 at 04:31:08PM -0700, Sami Tolvanen wrote: > KCFI is a forward-edge control-flow integrity scheme in the upcoming > Clang 16 release, which is more suitable for kernel use than the > existing CFI scheme used by CONFIG_CFI_CLANG. KCFI doesn't require > LTO, doesn't alter function references to point to a jump table, and > won't break function address equality. > > This series replaces the current arm64 CFI implementation with KCFI > and adds support for x86_64. > > KCFI requires assembly functions that are indirectly called from C > code to be annotated with type identifiers. As type information is > only available in C, the compiler emits expected type identifiers > into the symbol table, so they can be referenced from assembly > without having to hardcode type hashes. Patch 6 adds helper macros > for annotating functions, and patches 9 and 19 add annotations. > > In case of a type mismatch, KCFI always traps. To support error > handling, the compiler generates a .kcfi_traps section for x86_64, > which contains the locations of each trap, and for arm64, encodes > the necessary register information to the ESR. Patches 10 and 21 add > arch-specific error handlers. > > To test this series, you'll a ToT Clang toolchain. The series is > also available in GitHub: > > https://github.com/samitolvanen/linux/commits/kcfi-v4
This happily runs through all my initial testing hoops. :)
Tested-by: Kees Cook <keescook@chromium.org>
-- Kees Cook
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