diff options
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 80 |
1 files changed, 62 insertions, 18 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 99349547afed..9af3a597cc67 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -596,21 +596,22 @@ config STACKPROTECTOR_STRONG config ARCH_SUPPORTS_SHADOW_CALL_STACK bool help - An architecture should select this if it supports Clang's Shadow - Call Stack and implements runtime support for shadow stack + An architecture should select this if it supports the compiler's + Shadow Call Stack 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 + bool "Shadow Call Stack" + depends on ARCH_SUPPORTS_SHADOW_CALL_STACK depends on DYNAMIC_FTRACE_WITH_REGS || !FUNCTION_GRAPH_TRACER 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: + This option enables the compiler'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 the compiler's documentation: - https://clang.llvm.org/docs/ShadowCallStack.html + - Clang: https://clang.llvm.org/docs/ShadowCallStack.html + - GCC: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html#Instrumentation-Options Note that security guarantees in the kernel differ from the ones documented for user space. The kernel must store addresses @@ -1163,16 +1164,30 @@ config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET to the compiler, so it will attempt to add canary checks regardless of the static branch state. -config RANDOMIZE_KSTACK_OFFSET_DEFAULT - bool "Randomize kernel stack offset on syscall entry" +config RANDOMIZE_KSTACK_OFFSET + bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT + default y depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET + depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000 help The kernel stack offset can be randomized (after pt_regs) by roughly 5 bits of entropy, frustrating memory corruption attacks that depend on stack address determinism or - cross-syscall address exposures. This feature is controlled - by kernel boot param "randomize_kstack_offset=on/off", and this - config chooses the default boot state. + cross-syscall address exposures. + + The feature is controlled via the "randomize_kstack_offset=on/off" + kernel boot param, and if turned off has zero overhead due to its use + of static branches (see JUMP_LABEL). + + If unsure, say Y. + +config RANDOMIZE_KSTACK_OFFSET_DEFAULT + bool "Default state of kernel stack offset randomization" + depends on RANDOMIZE_KSTACK_OFFSET + help + Kernel stack offset randomization is controlled by kernel boot param + "randomize_kstack_offset=on/off", and this config chooses the default + boot state. config ARCH_OPTIONAL_KERNEL_RWX def_bool n @@ -1282,12 +1297,41 @@ config HAVE_STATIC_CALL_INLINE config HAVE_PREEMPT_DYNAMIC bool + +config HAVE_PREEMPT_DYNAMIC_CALL + bool depends on HAVE_STATIC_CALL - depends on GENERIC_ENTRY + select HAVE_PREEMPT_DYNAMIC help - Select this if the architecture support boot time preempt setting - on top of static calls. It is strongly advised to support inline - static call to avoid any overhead. + An architecture should select this if it can handle the preemption + model being selected at boot time using static calls. + + Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a + preemption function will be patched directly. + + Where an architecture does not select HAVE_STATIC_CALL_INLINE, any + call to a preemption function will go through a trampoline, and the + trampoline will be patched. + + It is strongly advised to support inline static call to avoid any + overhead. + +config HAVE_PREEMPT_DYNAMIC_KEY + bool + depends on HAVE_ARCH_JUMP_LABEL && CC_HAS_ASM_GOTO + select HAVE_PREEMPT_DYNAMIC + help + An architecture should select this if it can handle the preemption + model being selected at boot time using static keys. + + Each preemption function will be given an early return based on a + static key. This should have slightly lower overhead than non-inline + static calls, as this effectively inlines each trampoline into the + start of its callee. This may avoid redundant work, and may + integrate better with CFI schemes. + + This will have greater overhead than using inline static calls as + the call to the preemption function cannot be entirely elided. config ARCH_WANT_LD_ORPHAN_WARN bool |