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| author | Sami Tolvanen <samitolvanen@google.com> | 2020-04-27 09:00:07 -0700 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-05-15 16:35:45 +0100 |
| commit | d08b9f0ca6605e13dcb48f04e55a30545b3c71eb (patch) | |
| tree | 177893706ae16d9302dda4ee5f4894ac02e9b24e /arch/Kconfig | |
| parent | 6a8b55ed4056ea5559ebe4f6a4b247f627870d4c (diff) | |
| download | lwn-d08b9f0ca6605e13dcb48f04e55a30545b3c71eb.tar.gz lwn-d08b9f0ca6605e13dcb48f04e55a30545b3c71eb.zip | |
scs: Add support for Clang's Shadow Call Stack (SCS)
This change adds generic support for Clang's Shadow Call Stack,
which uses a shadow stack to protect return addresses from being
overwritten by an attacker. Details are available here:
https://clang.llvm.org/docs/ShadowCallStack.html
Note that security guarantees in the kernel differ from the ones
documented for user space. The kernel must store addresses of
shadow stacks in memory, which means an attacker capable reading
and writing arbitrary memory may be able to locate them and hijack
control flow by modifying the stacks.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
[will: Numerous cosmetic changes]
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 786a85d4ad40..334a3d9b19df 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -533,6 +533,30 @@ config STACKPROTECTOR_STRONG about 20% of all kernel functions, which increases the kernel code size by about 2%. +config ARCH_SUPPORTS_SHADOW_CALL_STACK + bool + help + An architecture should select this if it supports Clang's Shadow + Call Stack, has asm/scs.h, and implements runtime support for shadow + stack switching. + +config SHADOW_CALL_STACK + bool "Clang Shadow Call Stack" + depends on CC_IS_CLANG && ARCH_SUPPORTS_SHADOW_CALL_STACK + help + This option enables Clang's Shadow Call Stack, which uses a + shadow stack to protect function return addresses from being + overwritten by an attacker. More information can be found in + Clang's documentation: + + https://clang.llvm.org/docs/ShadowCallStack.html + + Note that security guarantees in the kernel differ from the + ones documented for user space. The kernel must store addresses + of shadow stacks in memory, which means an attacker capable of + reading and writing arbitrary memory may be able to locate them + and hijack control flow by modifying the stacks. + config HAVE_ARCH_WITHIN_STACK_FRAMES bool help |