@@ -1501,7 +1501,6 @@ config ARM64_PTR_AUTH
# which is only understood by binutils starting with version 2.33.1.
depends on LD_IS_LLD || LD_VERSION >= 233010000 || (CC_IS_GCC && GCC_VERSION < 90100)
depends on !CC_IS_CLANG || AS_HAS_CFI_NEGATE_RA_STATE
- depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
help
Pointer authentication (part of the ARMv8.3 Extensions) provides
instructions for signing and authenticating pointers against secret
@@ -1513,13 +1512,6 @@ config ARM64_PTR_AUTH
for each process at exec() time, with these keys being
context-switched along with the process.
- If the compiler supports the -mbranch-protection or
- -msign-return-address flag (e.g. GCC 7 or later), then this option
- will also cause the kernel itself to be compiled with return address
- protection. In this case, and if the target hardware is known to
- support pointer authentication, then CONFIG_STACKPROTECTOR can be
- disabled with minimal loss of protection.
-
The feature is detected at runtime. If the feature is not present in
hardware it will not be advertised to userspace/KVM guest nor will it
be enabled.
@@ -1530,6 +1522,22 @@ config ARM64_PTR_AUTH
but with the feature disabled. On such a system, this option should
not be selected.
+config ARM64_PTR_AUTH_KERNEL
+ bool "Enable support for pointer authentication for kernel"
+ default y
+ depends on ARM64_PTR_AUTH
+ depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_REGS)
+ help
+ Build the kernel with return address protection by
+ pointer authentication.
+
+ If the compiler supports the -mbranch-protection or
+ -msign-return-address flag (e.g. GCC 7 or later), then this option
+ will cause the kernel itself to be compiled with return address
+ protection. In this case, and if the target hardware is known to
+ support pointer authentication, then CONFIG_STACKPROTECTOR can be
+ disabled with minimal loss of protection.
+
This feature works with FUNCTION_GRAPH_TRACER option only if
DYNAMIC_FTRACE_WITH_REGS is enabled.
@@ -1618,7 +1626,7 @@ config ARM64_BTI_KERNEL
bool "Use Branch Target Identification for kernel"
default y
depends on ARM64_BTI
- depends on ARM64_PTR_AUTH
+ depends on ARM64_PTR_AUTH_KERNEL
depends on CC_HAS_BRANCH_PROT_PAC_RET_BTI
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94697
depends on !CC_IS_GCC || GCC_VERSION >= 100100
@@ -70,7 +70,7 @@ endif
# off, this will be overridden if we are using branch protection.
branch-prot-flags-y += $(call cc-option,-mbranch-protection=none)
-ifeq ($(CONFIG_ARM64_PTR_AUTH),y)
+ifeq ($(CONFIG_ARM64_PTR_AUTH_KERNEL),y)
branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all
# We enable additional protection for leaf functions as there is some
# narrow potential for ROP protection benefits and no substantial
@@ -446,7 +446,7 @@ void lkdtm_DOUBLE_FAULT(void)
#ifdef CONFIG_ARM64
static noinline void change_pac_parameters(void)
{
- if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH)) {
+ if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) {
/* Reset the keys of current task */
ptrauth_thread_init_kernel(current);
ptrauth_thread_switch_kernel(current);
@@ -460,8 +460,8 @@ noinline void lkdtm_CORRUPT_PAC(void)
#define CORRUPT_PAC_ITERATE 10
int i;
- if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH))
- pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH\n");
+ if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
+ pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n");
if (!system_supports_address_auth()) {
pr_err("FAIL: CPU lacks pointer authentication feature\n");
This new option makes possible to build the kernel with pointer authentication support for the user space while the kernel is not built with the pointer authentication. We have similar config structure for BTI. The default configuration will be the same after this patch. Signed-off-by: Daniel Kiss <daniel.kiss@arm.com> --- arch/arm64/Kconfig | 26 +++++++++++++++++--------- arch/arm64/Makefile | 2 +- drivers/misc/lkdtm/bugs.c | 6 +++--- 3 files changed, 21 insertions(+), 13 deletions(-)