The following commit has been merged into the x86/core branch of tip: Commit-ID: 4fd5f70ce14da230c6a29648c3d51a48ee0b4bfd Gitweb: https://git.kernel.org/tip/4fd5f70ce14da230c6a29648c3d51a48ee0b4bfd Author: Kees Cook <keescook@xxxxxxxxxxxx> AuthorDate: Tue, 01 Nov 2022 10:25:07 -07:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Sat, 05 Nov 2022 11:28:03 +01:00 x86/Kconfig: Enable kernel IBT by default The kernel IBT defense strongly mitigates the common "first step" of ROP attacks, by eliminating arbitrary stack pivots (that appear either at the end of a function or in immediate values), which cannot be reached if indirect calls must be to marked function entry addresses. IBT is also required to be enabled to gain the FineIBT feature when built with Kernel Control Flow Integrity. Additionally, given that this feature is runtime enabled via CPU ID, it clearly should be built in by default; it will only be enabled if the CPU supports it. The build takes 2 seconds longer, which seems a small price to pay for gaining this coverage by default. Suggested-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20221101172503.gonna.094-kees@xxxxxxxxxx --- arch/x86/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 479ee63..aaf1f0f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1856,7 +1856,7 @@ config CC_HAS_IBT config X86_KERNEL_IBT prompt "Indirect Branch Tracking" - bool + def_bool y depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f depends on !LD_IS_LLD || LLD_VERSION >= 140000
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