diff mbox series

[v7,23/27] x86/cet/shstk: ELF header parsing of Shadow Stack

Message ID 20190606200646.3951-24-yu-cheng.yu@intel.com (mailing list archive)
State New, archived
Headers show
Series Control-flow Enforcement: Shadow Stack | expand

Commit Message

Yu-cheng Yu June 6, 2019, 8:06 p.m. UTC 
Look in .note.gnu.property of an ELF file and check if Shadow Stack needs
to be enabled for the task.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 arch/x86/Kconfig             |  1 +
 arch/x86/kernel/process_64.c | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

Comments

Peter Zijlstra June 7, 2019, 7:54 a.m. UTC | #1 
On Thu, Jun 06, 2019 at 01:06:42PM -0700, Yu-cheng Yu wrote:

> +#ifdef CONFIG_ARCH_USE_GNU_PROPERTY
> +int arch_setup_property(void *ehdr, void *phdr, struct file *f, bool inter)
> +{
> +	int r;
> +	uint32_t property;

Flip those two lines around.

> +
> +	r = get_gnu_property(ehdr, phdr, f, GNU_PROPERTY_X86_FEATURE_1_AND,
> +			     &property);
> +
> +	memset(&current->thread.cet, 0, sizeof(struct cet_status));

It seems to me that memset would be better placed before
get_gnu_property().

> +	if (r)
> +		return r;
> +
> +	if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {

	if (r || !cpu_feature_enabled())
		return r;

> +		if (property & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
> +			r = cet_setup_shstk();
> +		if (r < 0)
> +			return r;
> +	}
> +	return r;

and loose the indent.

> +}
> +#endif
> -- 
> 2.17.1
>
diff mbox series

Patch

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1664918c2c1c..df8b57de75b2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1928,6 +1928,7 @@  config X86_INTEL_SHADOW_STACK_USER
 	select ARCH_USES_HIGH_VMA_FLAGS
 	select X86_INTEL_CET
 	select ARCH_HAS_SHSTK
+	select ARCH_USE_GNU_PROPERTY
 	---help---
 	  Shadow stack provides hardware protection against program stack
 	  corruption.  Only when all the following are true will an application
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 250e4c4ac6d9..c51df5b4e116 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -828,3 +828,27 @@  unsigned long KSTK_ESP(struct task_struct *task)
 {
 	return task_pt_regs(task)->sp;
 }
+
+#ifdef CONFIG_ARCH_USE_GNU_PROPERTY
+int arch_setup_property(void *ehdr, void *phdr, struct file *f, bool inter)
+{
+	int r;
+	uint32_t property;
+
+	r = get_gnu_property(ehdr, phdr, f, GNU_PROPERTY_X86_FEATURE_1_AND,
+			     &property);
+
+	memset(&current->thread.cet, 0, sizeof(struct cet_status));
+
+	if (r)
+		return r;
+
+	if (cpu_feature_enabled(X86_FEATURE_SHSTK)) {
+		if (property & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+			r = cet_setup_shstk();
+		if (r < 0)
+			return r;
+	}
+	return r;
+}
+#endif