mirror of
https://github.com/torvalds/linux.git
synced 2024-12-15 15:41:58 +00:00
2bd926b439
This commit splits the current CONFIG_KASAN config option into two: 1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one that exists now); 2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode. The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have another hardware tag-based KASAN mode, that will rely on hardware memory tagging support in arm64. With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to instrument kernel files with -fsantize=kernel-hwaddress (except the ones for which KASAN_SANITIZE := n is set). Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes. This commit also adds empty placeholder (for now) implementation of tag-based KASAN specific hooks inserted by the compiler and adjusts common hooks implementation. While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will enable once all the infrastracture code has been added. Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
132 lines
4.7 KiB
Plaintext
132 lines
4.7 KiB
Plaintext
# This config refers to the generic KASAN mode.
|
|
config HAVE_ARCH_KASAN
|
|
bool
|
|
|
|
config HAVE_ARCH_KASAN_SW_TAGS
|
|
bool
|
|
|
|
config CC_HAS_KASAN_GENERIC
|
|
def_bool $(cc-option, -fsanitize=kernel-address)
|
|
|
|
config CC_HAS_KASAN_SW_TAGS
|
|
def_bool $(cc-option, -fsanitize=kernel-hwaddress)
|
|
|
|
config 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 (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
|
|
help
|
|
Enables KASAN (KernelAddressSANitizer) - runtime memory debugger,
|
|
designed to find out-of-bounds accesses and use-after-free bugs.
|
|
See Documentation/dev-tools/kasan.rst for details.
|
|
|
|
choice
|
|
prompt "KASAN mode"
|
|
depends on KASAN
|
|
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).
|
|
Both generic and tag-based KASAN are strictly debugging features.
|
|
|
|
config KASAN_GENERIC
|
|
bool "Generic mode"
|
|
depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
|
|
depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
|
|
select SLUB_DEBUG if SLUB
|
|
select CONSTRUCTORS
|
|
select STACKDEPOT
|
|
help
|
|
Enables generic KASAN mode.
|
|
Supported in both GCC and Clang. With GCC it requires version 4.9.2
|
|
or later for basic support and version 5.0 or later for detection of
|
|
out-of-bounds accesses for stack and global variables and for inline
|
|
instrumentation mode (CONFIG_KASAN_INLINE). With Clang it requires
|
|
version 3.7.0 or later and it doesn't support detection of
|
|
out-of-bounds accesses for global variables yet.
|
|
This mode consumes about 1/8th of available memory at kernel start
|
|
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).
|
|
|
|
config KASAN_SW_TAGS
|
|
bool "Software tag-based mode"
|
|
depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
|
|
depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
|
|
select SLUB_DEBUG if SLUB
|
|
select CONSTRUCTORS
|
|
select STACKDEPOT
|
|
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 version 7.0.0 or later.
|
|
This mode consumes about 1/16th of available memory at kernel start
|
|
and introduces an overhead of ~20% for the rest of the allocations.
|
|
This mode may potentially introduce problems relating to pointer
|
|
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).
|
|
|
|
endchoice
|
|
|
|
config KASAN_EXTRA
|
|
bool "KASAN: extra checks"
|
|
depends on KASAN_GENERIC && DEBUG_KERNEL && !COMPILE_TEST
|
|
help
|
|
This enables further checks in generic KASAN, for now it only
|
|
includes the address-use-after-scope check that can lead to
|
|
excessive kernel stack usage, frame size warnings and longer
|
|
compile time.
|
|
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715
|
|
|
|
choice
|
|
prompt "Instrumentation type"
|
|
depends on KASAN
|
|
default KASAN_OUTLINE
|
|
|
|
config KASAN_OUTLINE
|
|
bool "Outline instrumentation"
|
|
help
|
|
Before every memory access compiler insert function call
|
|
__asan_load*/__asan_store*. These functions performs check
|
|
of shadow memory. This is slower than inline instrumentation,
|
|
however it doesn't bloat size of kernel's .text section so
|
|
much as inline does.
|
|
|
|
config KASAN_INLINE
|
|
bool "Inline instrumentation"
|
|
help
|
|
Compiler directly inserts code checking shadow memory before
|
|
memory accesses. This is faster than outline (in some workloads
|
|
it gives about x2 boost over outline instrumentation), but
|
|
make kernel's .text size much bigger.
|
|
For CONFIG_KASAN_GENERIC this requires GCC 5.0 or later.
|
|
|
|
endchoice
|
|
|
|
config KASAN_S390_4_LEVEL_PAGING
|
|
bool "KASan: use 4-level paging"
|
|
depends on KASAN && S390
|
|
help
|
|
Compiling the kernel with KASan disables automatic 3-level vs
|
|
4-level paging selection. 3-level paging is used by default (up
|
|
to 3TB of RAM with KASan enabled). This options allows to force
|
|
4-level paging instead.
|
|
|
|
config TEST_KASAN
|
|
tristate "Module for testing KASAN for bug detection"
|
|
depends on m && KASAN
|
|
help
|
|
This is a test module doing various nasty things like
|
|
out of bounds accesses, use after free. It is useful for testing
|
|
kernel debugging features like KASAN.
|