kbuild: rust: Enable KASAN support

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

Suggested-by: Miguel Ojeda <[email protected]>
Signed-off-by: Matthew Maurer <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Applied "SW_TAGS KASAN" nit. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index aab4154af00a7ed57ac77eaa31f2dcb354ea649b..693dbbebebba10503538adf80f4a206d7c25cb72 100644 (file)
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -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

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index fe3668dc4954b2afb945e75768ac0846d50a0672..27999da3d38264862e6eb0dc2a99be16549611b2 100644 (file)
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -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
 

diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 087c1d13d33ba2019a2d6a0d5b007e4e538f976f..0d00ac3723b5e5971acb47478d6c2a63bc4ed6c6 100644 (file)
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -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