From d08b9f0ca6605e13dcb48f04e55a30545b3c71eb Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Mon, 27 Apr 2020 09:00:07 -0700 Subject: 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 Reviewed-by: Kees Cook Reviewed-by: Miguel Ojeda [will: Numerous cosmetic changes] Signed-off-by: Will Deacon --- init/init_task.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'init') diff --git a/init/init_task.c b/init/init_task.c index bd403ed3e418..169e34066d35 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -50,6 +51,13 @@ static struct sighand_struct init_sighand = { .signalfd_wqh = __WAIT_QUEUE_HEAD_INITIALIZER(init_sighand.signalfd_wqh), }; +#ifdef CONFIG_SHADOW_CALL_STACK +unsigned long init_shadow_call_stack[SCS_SIZE / sizeof(long)] + __init_task_data = { + [(SCS_SIZE / sizeof(long)) - 1] = SCS_END_MAGIC +}; +#endif + /* * Set up the first task table, touch at your own risk!. Base=0, * limit=0x1fffff (=2MB) -- cgit v1.2.3