arm64: Add CONFIG_CC_STACKPROTECTOR

arm64 currently lacks support for -fstack-protector. Add
similar functionality to arm to detect stack corruption.

Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit c0c264ae5112d1cdb7d37d4e208b7a7e766a7418)
Signed-off-by: Mark Brown <broonie@kernel.org>
Conflicts:
	arch/arm64/Kconfig

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 65044ae9d2387b702184ece5fc04aa01b2b765e2..4142cab9d4ff733c3843dcfc52e3519a76427c1c 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -25,6 +25,7 @@ config ARM64
        select HARDIRQS_SW_RESEND
        select HAVE_ARCH_KGDB
        select HAVE_ARCH_TRACEHOOK
+       select HAVE_CC_STACKPROTECTOR
        select HAVE_DEBUG_BUGVERBOSE
        select HAVE_DEBUG_KMEMLEAK
        select HAVE_DMA_API_DEBUG

diff --git a/arch/arm64/include/asm/stackprotector.h b/arch/arm64/include/asm/stackprotector.h
new file mode 100644 (file)
index 0000000..fe5e287
--- /dev/null
+++ b/arch/arm64/include/asm/stackprotector.h
@@ -0,0 +1,38 @@
+/*
+ * GCC stack protector support.
+ *
+ * Stack protector works by putting predefined pattern at the start of
+ * the stack frame and verifying that it hasn't been overwritten when
+ * returning from the function.  The pattern is called stack canary
+ * and gcc expects it to be defined by a global variable called
+ * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP
+ * we cannot have a different canary value per task.
+ */
+
+#ifndef __ASM_STACKPROTECTOR_H
+#define __ASM_STACKPROTECTOR_H
+
+#include <linux/random.h>
+#include <linux/version.h>
+
+extern unsigned long __stack_chk_guard;
+
+/*
+ * Initialize the stackprotector canary value.
+ *
+ * NOTE: this must only be called from functions that never return,
+ * and it must always be inlined.
+ */
+static __always_inline void boot_init_stack_canary(void)
+{
+       unsigned long canary;
+
+       /* Try to get a semi random initial value. */
+       get_random_bytes(&canary, sizeof(canary));
+       canary ^= LINUX_VERSION_CODE;
+
+       current->stack_canary = canary;
+       __stack_chk_guard = current->stack_canary;
+}
+
+#endif /* _ASM_STACKPROTECTOR_H */

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 57bd961f29176002dd911e8991d462da924e1ec6..feb01cf4b2552d88c390d9dc519f533695d25f39 100644 (file)
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -50,6 +50,12 @@
 #include <asm/processor.h>
 #include <asm/stacktrace.h>
 
+#ifdef CONFIG_CC_STACKPROTECTOR
+#include <linux/stackprotector.h>
+unsigned long __stack_chk_guard __read_mostly;
+EXPORT_SYMBOL(__stack_chk_guard);
+#endif
+
 static void setup_restart(void)
 {
        /*