Commit e3117404 authored by Matthew Maurer's avatar Matthew Maurer Committed by Miguel Ojeda
Browse files

kbuild: rust: Enable KASAN support 



Rust supports KASAN via LLVM, but prior to this patch, the flags aren't
set properly.

Suggested-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Signed-off-by: default avatarMatthew Maurer <mmaurer@google.com>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20240820194910.187826-4-mmaurer@google.com


[ Applied "SW_TAGS KASAN" nit. - Miguel ]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent f64e2f3a

scripts/Makefile.kasan

+41 −16
Original line number Diff line number Diff line
@@ -12,6 +12,11 @@ endif 
KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)



cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1)))

rustc-param = $(call rustc-option, -Cllvm-args=-$(1),)



check-args = $(foreach arg,$(2),$(call $(1),$(arg)))



kasan_params :=



ifdef CONFIG_KASAN_STACK

	stack_enable := 1
@@ -41,39 +46,59 @@ CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ 
		$(call cc-option, -fsanitize=kernel-address \

		-mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET)))



# Now, add other parameters enabled similarly in both GCC and Clang.

# As some of them are not supported by older compilers, use cc-param.

CFLAGS_KASAN += $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \

		$(call cc-param,asan-stack=$(stack_enable)) \

		$(call cc-param,asan-instrument-allocas=1) \

		$(call cc-param,asan-globals=1)

# The minimum supported `rustc` version has a minimum supported LLVM

# version late enough that we can assume support for -asan-mapping-offset.

RUSTFLAGS_KASAN := -Zsanitizer=kernel-address \

		   -Zsanitizer-recover=kernel-address \

		   -Cllvm-args=-asan-mapping-offset=$(KASAN_SHADOW_OFFSET)



# Now, add other parameters enabled similarly in GCC, Clang, and rustc.

# As some of them are not supported by older compilers, these will be filtered

# through `cc-param` or `rust-param` as applicable.

kasan_params += asan-instrumentation-with-call-threshold=$(call_threshold) \

		asan-stack=$(stack_enable) \

		asan-instrument-allocas=1 \

		asan-globals=1



# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*()

# instead. With compilers that don't support this option, compiler-inserted

# memintrinsics won't be checked by KASAN on GENERIC_ENTRY architectures.

CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)

kasan_params += asan-kernel-mem-intrinsic-prefix=1



endif # CONFIG_KASAN_GENERIC



ifdef CONFIG_KASAN_SW_TAGS



CFLAGS_KASAN := -fsanitize=kernel-hwaddress



# This sets flags that will enable SW_TAGS KASAN once enabled in Rust. These

# will not work today, and is guarded against in dependencies for CONFIG_RUST.

RUSTFLAGS_KASAN := -Zsanitizer=kernel-hwaddress \

		   -Zsanitizer-recover=kernel-hwaddress



ifdef CONFIG_KASAN_INLINE

	instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET))

	kasan_params += hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)

else

	instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1)

	kasan_params += hwasan-instrument-with-calls=1

endif



CFLAGS_KASAN := -fsanitize=kernel-hwaddress \

		$(call cc-param,hwasan-instrument-stack=$(stack_enable)) \

		$(call cc-param,hwasan-use-short-granules=0) \

		$(call cc-param,hwasan-inline-all-checks=0) \

		$(instrumentation_flags)

kasan_params += hwasan-instrument-stack=$(stack_enable) \

		hwasan-use-short-granules=0 \

		hwasan-inline-all-checks=0



# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*().

ifeq ($(call clang-min-version, 150000)$(call gcc-min-version, 130000),y)

	CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1)

	kasan_params += hwasan-kernel-mem-intrinsic-prefix=1

endif



endif # CONFIG_KASAN_SW_TAGS



export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE
 
# Add all as-supported KASAN LLVM parameters requested by the configuration.

CFLAGS_KASAN += $(call check-args, cc-param, $(kasan_params))



ifdef CONFIG_RUST

	# Avoid calling `rustc-param` unless Rust is enabled.

	RUSTFLAGS_KASAN += $(call check-args, rustc-param, $(kasan_params))

endif # CONFIG_RUST



export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE RUSTFLAGS_KASAN

scripts/Makefile.lib

+3 −0
Original line number Diff line number Diff line
@@ -167,6 +167,9 @@ ifneq ($(CONFIG_KASAN_HW_TAGS),y) 
_c_flags += $(if $(patsubst n%,, \

		$(KASAN_SANITIZE_$(target-stem).o)$(KASAN_SANITIZE)$(is-kernel-object)), \

		$(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE))

_rust_flags += $(if $(patsubst n%,, \

		$(KASAN_SANITIZE_$(target-stem).o)$(KASAN_SANITIZE)$(is-kernel-object)), \

		$(RUSTFLAGS_KASAN))

endif

endif

scripts/generate_rust_target.rs

+1 −1
Original line number Diff line number Diff line
@@ -207,7 +207,7 @@ fn main() { 
        }

        ts.push("features", features);

        ts.push("llvm-target", "x86_64-linux-gnu");

        ts.push("supported-sanitizers", ["kcfi"]);

        ts.push("supported-sanitizers", ["kcfi", "kernel-address"]);

        ts.push("target-pointer-width", "64");

    } else if cfg.has("X86_32") {

        // This only works on UML, as i386 otherwise needs regparm support in rustc