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 <[email protected]>
Co-developed-by: Vincenzo Frascino <[email protected]>
Signed-off-by: Vincenzo Frascino <[email protected]>
Reviewed-by: Marco Elver <[email protected]>
---
Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe
---
lib/Kconfig.kasan | 58 +++++++++++++++++++++++++++++++++--------------
1 file changed, 41 insertions(+), 17 deletions(-)
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index ec59a0e26d09..e5f27ec8b254 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
@@ -20,11 +23,11 @@ config CC_HAS_WORKING_NOSANITIZE_ADDRESS
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 +40,24 @@ 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 +70,6 @@ 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 +77,15 @@ 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 +93,27 @@ 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 +137,7 @@ 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
--
2.29.2.222.g5d2a92d10f8-goog
On Tue, Nov 10, 2020 at 11:12 PM Andrey Konovalov <[email protected]> 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 <[email protected]>
> Co-developed-by: Vincenzo Frascino <[email protected]>
> Signed-off-by: Vincenzo Frascino <[email protected]>
> Reviewed-by: Marco Elver <[email protected]>
> ---
> Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe
> ---
> lib/Kconfig.kasan | 58 +++++++++++++++++++++++++++++++++--------------
> 1 file changed, 41 insertions(+), 17 deletions(-)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index ec59a0e26d09..e5f27ec8b254 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
> @@ -20,11 +23,11 @@ config CC_HAS_WORKING_NOSANITIZE_ADDRESS
It might make sense to add a comment to
CC_HAS_WORKING_NOSANITIZE_ADDRESS describing which modes need it (and
why).
On Wed, Nov 11, 2020 at 4:58 PM Alexander Potapenko <[email protected]> wrote:
>
> On Tue, Nov 10, 2020 at 11:12 PM Andrey Konovalov <[email protected]> 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 <[email protected]>
> > Co-developed-by: Vincenzo Frascino <[email protected]>
> > Signed-off-by: Vincenzo Frascino <[email protected]>
> > Reviewed-by: Marco Elver <[email protected]>
> > ---
> > Change-Id: I246c2def9fffa6563278db1bddfbe742ca7bdefe
> > ---
> > lib/Kconfig.kasan | 58 +++++++++++++++++++++++++++++++++--------------
> > 1 file changed, 41 insertions(+), 17 deletions(-)
> >
> > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> > index ec59a0e26d09..e5f27ec8b254 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
> > @@ -20,11 +23,11 @@ config CC_HAS_WORKING_NOSANITIZE_ADDRESS
> It might make sense to add a comment to
> CC_HAS_WORKING_NOSANITIZE_ADDRESS describing which modes need it (and
> why).
OK, will do in v10, thanks!