diff mbox series

[mm,v10,23/42] kasan: introduce CONFIG_KASAN_HW_TAGS

Message ID da7fc94554c52c63f957d82e46c5bc8a718b2b96.1605305705.git.andreyknvl@google.com (mailing list archive)
State New
Headers show
Series kasan: add hardware tag-based mode for arm64 | expand

Commit Message

Andrey Konovalov Nov. 13, 2020, 10:15 p.m. UTC
This patch adds a configuration option for a new KASAN mode called
hardware tag-based KASAN. This mode uses the memory tagging approach
like the software tag-based mode, but relies on arm64 Memory Tagging
Extension feature for tag management and access checking.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
---
Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe
---
 lib/Kconfig.kasan | 61 ++++++++++++++++++++++++++++++++++-------------
 1 file changed, 44 insertions(+), 17 deletions(-)

Comments

Alexander Potapenko Nov. 18, 2020, 4:04 p.m. UTC | #1
On Fri, Nov 13, 2020 at 11:17 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> This patch adds a configuration option for a new KASAN mode called
> hardware tag-based KASAN. This mode uses the memory tagging approach
> like the software tag-based mode, but relies on arm64 Memory Tagging
> Extension feature for tag management and access checking.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>

> ---
> Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe
> ---
>  lib/Kconfig.kasan | 61 ++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 44 insertions(+), 17 deletions(-)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index c0e9e7874122..f5fa4ba126bf 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -6,7 +6,10 @@ config HAVE_ARCH_KASAN
>  config HAVE_ARCH_KASAN_SW_TAGS
>         bool
>
> -config HAVE_ARCH_KASAN_VMALLOC
> +config HAVE_ARCH_KASAN_HW_TAGS
> +       bool
> +
> +config HAVE_ARCH_KASAN_VMALLOC
>         bool
>
>  config CC_HAS_KASAN_GENERIC
> @@ -15,16 +18,19 @@ config CC_HAS_KASAN_GENERIC
>  config CC_HAS_KASAN_SW_TAGS
>         def_bool $(cc-option, -fsanitize=kernel-hwaddress)
>
> +# This option is only required for software KASAN modes.
> +# Old GCC versions don't have proper support for no_sanitize_address.
> +# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124 for details.
>  config CC_HAS_WORKING_NOSANITIZE_ADDRESS
>         def_bool !CC_IS_GCC || GCC_VERSION >= 80300
>
>  menuconfig KASAN
>         bool "KASAN: runtime memory debugger"
> -       depends on (HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
> -                  (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)
> +       depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
> +                    (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \
> +                   CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \
> +                  HAVE_ARCH_KASAN_HW_TAGS
>         depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
> -       depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
> -       select CONSTRUCTORS
>         select STACKDEPOT
>         help
>           Enables KASAN (KernelAddressSANitizer) - runtime memory debugger,
> @@ -37,18 +43,24 @@ choice
>         prompt "KASAN mode"
>         default KASAN_GENERIC
>         help
> -         KASAN has two modes: generic KASAN (similar to userspace ASan,
> -         x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC) and
> -         software tag-based KASAN (a version based on software memory
> -         tagging, arm64 only, similar to userspace HWASan, enabled with
> -         CONFIG_KASAN_SW_TAGS).
> +         KASAN has three modes:
> +         1. generic KASAN (similar to userspace ASan,
> +            x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC),
> +         2. software tag-based KASAN (arm64 only, based on software
> +            memory tagging (similar to userspace HWASan), enabled with
> +            CONFIG_KASAN_SW_TAGS), and
> +         3. hardware tag-based KASAN (arm64 only, based on hardware
> +            memory tagging, enabled with CONFIG_KASAN_HW_TAGS).
> +
> +         All KASAN modes are strictly debugging features.
>
> -         Both generic and tag-based KASAN are strictly debugging features.
> +         For better error reports enable CONFIG_STACKTRACE.
>
>  config KASAN_GENERIC
>         bool "Generic mode"
>         depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
>         select SLUB_DEBUG if SLUB
> +       select CONSTRUCTORS
>         help
>           Enables generic KASAN mode.
>
> @@ -61,8 +73,6 @@ config KASAN_GENERIC
>           and introduces an overhead of ~x1.5 for the rest of the allocations.
>           The performance slowdown is ~x3.
>
> -         For better error detection enable CONFIG_STACKTRACE.
> -
>           Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
>           (the resulting kernel does not boot).
>
> @@ -70,11 +80,15 @@ config KASAN_SW_TAGS
>         bool "Software tag-based mode"
>         depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
>         select SLUB_DEBUG if SLUB
> +       select CONSTRUCTORS
>         help
>           Enables software tag-based KASAN mode.
>
> -         This mode requires Top Byte Ignore support by the CPU and therefore
> -         is only supported for arm64. This mode requires Clang.
> +         This mode require software memory tagging support in the form of
> +         HWASan-like compiler instrumentation.
> +
> +         Currently this mode is only implemented for arm64 CPUs and relies on
> +         Top Byte Ignore. This mode requires Clang.
>
>           This mode consumes about 1/16th of available memory at kernel start
>           and introduces an overhead of ~20% for the rest of the allocations.
> @@ -82,15 +96,27 @@ config KASAN_SW_TAGS
>           casting and comparison, as it embeds tags into the top byte of each
>           pointer.
>
> -         For better error detection enable CONFIG_STACKTRACE.
> -
>           Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB
>           (the resulting kernel does not boot).
>
> +config KASAN_HW_TAGS
> +       bool "Hardware tag-based mode"
> +       depends on HAVE_ARCH_KASAN_HW_TAGS
> +       depends on SLUB
> +       help
> +         Enables hardware tag-based KASAN mode.
> +
> +         This mode requires hardware memory tagging support, and can be used
> +         by any architecture that provides it.
> +
> +         Currently this mode is only implemented for arm64 CPUs starting from
> +         ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore.
> +
>  endchoice
>
>  choice
>         prompt "Instrumentation type"
> +       depends on KASAN_GENERIC || KASAN_SW_TAGS
>         default KASAN_OUTLINE
>
>  config KASAN_OUTLINE
> @@ -114,6 +140,7 @@ endchoice
>
>  config KASAN_STACK_ENABLE
>         bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
> +       depends on KASAN_GENERIC || KASAN_SW_TAGS
>         help
>           The LLVM stack address sanitizer has a know problem that
>           causes excessive stack usage in a lot of functions, see
> --
> 2.29.2.299.gdc1121823c-goog
>
diff mbox series

Patch

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index c0e9e7874122..f5fa4ba126bf 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -6,7 +6,10 @@  config HAVE_ARCH_KASAN
 config HAVE_ARCH_KASAN_SW_TAGS
 	bool
 
-config	HAVE_ARCH_KASAN_VMALLOC
+config HAVE_ARCH_KASAN_HW_TAGS
+	bool
+
+config HAVE_ARCH_KASAN_VMALLOC
 	bool
 
 config CC_HAS_KASAN_GENERIC
@@ -15,16 +18,19 @@  config CC_HAS_KASAN_GENERIC
 config CC_HAS_KASAN_SW_TAGS
 	def_bool $(cc-option, -fsanitize=kernel-hwaddress)
 
+# This option is only required for software KASAN modes.
+# Old GCC versions don't have proper support for no_sanitize_address.
+# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124 for details.
 config CC_HAS_WORKING_NOSANITIZE_ADDRESS
 	def_bool !CC_IS_GCC || GCC_VERSION >= 80300
 
 menuconfig KASAN
 	bool "KASAN: runtime memory debugger"
-	depends on (HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
-		   (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)
+	depends on (((HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC) || \
+		     (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \
+		    CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \
+		   HAVE_ARCH_KASAN_HW_TAGS
 	depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
-	depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
-	select CONSTRUCTORS
 	select STACKDEPOT
 	help
 	  Enables KASAN (KernelAddressSANitizer) - runtime memory debugger,
@@ -37,18 +43,24 @@  choice
 	prompt "KASAN mode"
 	default KASAN_GENERIC
 	help
-	  KASAN has two modes: generic KASAN (similar to userspace ASan,
-	  x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC) and
-	  software tag-based KASAN (a version based on software memory
-	  tagging, arm64 only, similar to userspace HWASan, enabled with
-	  CONFIG_KASAN_SW_TAGS).
+	  KASAN has three modes:
+	  1. generic KASAN (similar to userspace ASan,
+	     x86_64/arm64/xtensa, enabled with CONFIG_KASAN_GENERIC),
+	  2. software tag-based KASAN (arm64 only, based on software
+	     memory tagging (similar to userspace HWASan), enabled with
+	     CONFIG_KASAN_SW_TAGS), and
+	  3. hardware tag-based KASAN (arm64 only, based on hardware
+	     memory tagging, enabled with CONFIG_KASAN_HW_TAGS).
+
+	  All KASAN modes are strictly debugging features.
 
-	  Both generic and tag-based KASAN are strictly debugging features.
+	  For better error reports enable CONFIG_STACKTRACE.
 
 config KASAN_GENERIC
 	bool "Generic mode"
 	depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
 	select SLUB_DEBUG if SLUB
+	select CONSTRUCTORS
 	help
 	  Enables generic KASAN mode.
 
@@ -61,8 +73,6 @@  config KASAN_GENERIC
 	  and introduces an overhead of ~x1.5 for the rest of the allocations.
 	  The performance slowdown is ~x3.
 
-	  For better error detection enable CONFIG_STACKTRACE.
-
 	  Currently CONFIG_KASAN_GENERIC doesn't work with CONFIG_DEBUG_SLAB
 	  (the resulting kernel does not boot).
 
@@ -70,11 +80,15 @@  config KASAN_SW_TAGS
 	bool "Software tag-based mode"
 	depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
 	select SLUB_DEBUG if SLUB
+	select CONSTRUCTORS
 	help
 	  Enables software tag-based KASAN mode.
 
-	  This mode requires Top Byte Ignore support by the CPU and therefore
-	  is only supported for arm64. This mode requires Clang.
+	  This mode require software memory tagging support in the form of
+	  HWASan-like compiler instrumentation.
+
+	  Currently this mode is only implemented for arm64 CPUs and relies on
+	  Top Byte Ignore. This mode requires Clang.
 
 	  This mode consumes about 1/16th of available memory at kernel start
 	  and introduces an overhead of ~20% for the rest of the allocations.
@@ -82,15 +96,27 @@  config KASAN_SW_TAGS
 	  casting and comparison, as it embeds tags into the top byte of each
 	  pointer.
 
-	  For better error detection enable CONFIG_STACKTRACE.
-
 	  Currently CONFIG_KASAN_SW_TAGS doesn't work with CONFIG_DEBUG_SLAB
 	  (the resulting kernel does not boot).
 
+config KASAN_HW_TAGS
+	bool "Hardware tag-based mode"
+	depends on HAVE_ARCH_KASAN_HW_TAGS
+	depends on SLUB
+	help
+	  Enables hardware tag-based KASAN mode.
+
+	  This mode requires hardware memory tagging support, and can be used
+	  by any architecture that provides it.
+
+	  Currently this mode is only implemented for arm64 CPUs starting from
+	  ARMv8.5 and relies on Memory Tagging Extension and Top Byte Ignore.
+
 endchoice
 
 choice
 	prompt "Instrumentation type"
+	depends on KASAN_GENERIC || KASAN_SW_TAGS
 	default KASAN_OUTLINE
 
 config KASAN_OUTLINE
@@ -114,6 +140,7 @@  endchoice
 
 config KASAN_STACK_ENABLE
 	bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
+	depends on KASAN_GENERIC || KASAN_SW_TAGS
 	help
 	  The LLVM stack address sanitizer has a know problem that
 	  causes excessive stack usage in a lot of functions, see