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arm64: Add CONFIG_CC_STACKPROTECTOR

PATCH New Laura Abbott 3 participants 3 messages Jun 25, 2014 – Jul 10, 2014 arm64

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Laura Abbott

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#0 lore raw

PATCH v3 1/1 arm64: Add CONFIG_CC_STACKPROTECTOR

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

Cc Will Deacon <[email protected]>
Cc Catalin Marinas <[email protected]>
Acked-by Kees Cook <[email protected]>
Signed-off-by Laura Abbott <[email protected]>
---
 arch/arm64/Kconfig                      |  1 +
 arch/arm64/include/asm/stackprotector.h | 38 +++++++++++++++++++++++++++++++++
 arch/arm64/kernel/process.c             |  6 ++++++
 3 files changed, 45 insertions(+)
 create mode 100644 arch/arm64/include/asm/stackprotector.h
arch/arm64/Kconfig +1 -0
index a474de34..f865436 100644
@@ -32,6 +32,7 @@ config ARM64
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_C_RECORDMCOUNT
+	select HAVE_CC_STACKPROTECTOR
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_API_DEBUG
arch/arm64/include/asm/stackprotector.h new file +38 -0
new file mode 100644
index 0000000..fe5e287
@@ -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 */
arch/arm64/kernel/process.c +6 -0
index 43b7c34..1309d64 100644
@@ -51,6 +51,12 @@
 #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)
 {
 	/*
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#2 lore raw

PATCH v3 1/1 arm64: Add CONFIG_CC_STACKPROTECTOR

In reply to Laura Abbott
Quoted 7 lines · Laura Abbott

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

Cc Will Deacon <[email protected]>
Cc Catalin Marinas <[email protected]>
Acked-by Kees Cook <[email protected]>
Signed-off-by Laura Abbott <[email protected]>
Quoted 6 lines
---
 arch/arm64/Kconfig                      |  1 +
 arch/arm64/include/asm/stackprotector.h | 38 +++++++++++++++++++++++++++++++++
 arch/arm64/kernel/process.c             |  6 ++++++
 3 files changed, 45 insertions(+)
 create mode 100644 arch/arm64/include/asm/stackprotector.h

Applied for 3.17. Thanks.

Signature · 1 line
Catalin