| Message ID | 20201229213053.16395-3-yu-cheng.yu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Control-flow Enforcement: Shadow Stack | expand |
On Tue, Dec 29, 2020 at 01:30:29PM -0800, Yu-cheng Yu wrote: > Shadow Stack provides protection against function return address > corruption. It is active when the processor supports it, the kernel has > CONFIG_X86_CET_USER enabled, and the application is built for the feature. > This is only implemented for the 64-bit kernel. When it is enabled, legacy > non-Shadow Stack applications continue to work, but without protection. > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > --- > arch/x86/Kconfig | 22 ++++++++++++++++++++++ > arch/x86/Kconfig.assembler | 5 +++++ > 2 files changed, 27 insertions(+) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 7b6dd10b162a..72cff400b9ae 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1950,6 +1950,28 @@ config X86_SGX > > If unsure, say N. > > +config ARCH_HAS_SHADOW_STACK > + def_bool n > + > +config X86_CET_USER That thing needs to be X86_CET. How many times do I need to type this before you do it?
On 1/19/2021 3:06 AM, Borislav Petkov wrote: > On Tue, Dec 29, 2020 at 01:30:29PM -0800, Yu-cheng Yu wrote: >> Shadow Stack provides protection against function return address >> corruption. It is active when the processor supports it, the kernel has >> CONFIG_X86_CET_USER enabled, and the application is built for the feature. >> This is only implemented for the 64-bit kernel. When it is enabled, legacy >> non-Shadow Stack applications continue to work, but without protection. >> >> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> >> --- >> arch/x86/Kconfig | 22 ++++++++++++++++++++++ >> arch/x86/Kconfig.assembler | 5 +++++ >> 2 files changed, 27 insertions(+) >> >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >> index 7b6dd10b162a..72cff400b9ae 100644 >> --- a/arch/x86/Kconfig >> +++ b/arch/x86/Kconfig >> @@ -1950,6 +1950,28 @@ config X86_SGX >> >> If unsure, say N. >> >> +config ARCH_HAS_SHADOW_STACK >> + def_bool n >> + >> +config X86_CET_USER > > That thing needs to be X86_CET. How many times do I need to type this > before you do it? > Yes, I totally understand that now. I was still thinking about separately enabling user/kernel mode. Perhaps I should have communicated that thought before the change. Sorry about that. I will update it. -- Yu-cheng
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7b6dd10b162a..72cff400b9ae 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1950,6 +1950,28 @@ config X86_SGX If unsure, say N. +config ARCH_HAS_SHADOW_STACK + def_bool n + +config X86_CET_USER + prompt "Intel Control-flow protection for user-mode" + def_bool n + depends on CPU_SUP_INTEL && X86_64 + depends on AS_WRUSS + select ARCH_USES_HIGH_VMA_FLAGS + select ARCH_HAS_SHADOW_STACK + help + Control-flow protection is a hardware security hardening feature + that detects function-return address or jump target changes by + malicious code. Applications must be enabled to use it, and old + userspace does not get protection "for free". + Support for this feature is present on processors released in + 2020 or later. Enabling this feature increases kernel text size + by 3.7 KB. + See Documentation/x86/intel_cet.rst for more information. + + If unsure, say N. + config EFI bool "EFI runtime service support" depends on ACPI diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler index 26b8c08e2fc4..00c79dd93651 100644 --- a/arch/x86/Kconfig.assembler +++ b/arch/x86/Kconfig.assembler @@ -19,3 +19,8 @@ config AS_TPAUSE def_bool $(as-instr,tpause %ecx) help Supported by binutils >= 2.31.1 and LLVM integrated assembler >= V7 + +config AS_WRUSS + def_bool $(as-instr,wrussq %rax$(comma)(%rbx)) + help + Supported by binutils >= 2.31 and LLVM integrated assembler
Shadow Stack provides protection against function return address corruption. It is active when the processor supports it, the kernel has CONFIG_X86_CET_USER enabled, and the application is built for the feature. This is only implemented for the 64-bit kernel. When it is enabled, legacy non-Shadow Stack applications continue to work, but without protection. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> --- arch/x86/Kconfig | 22 ++++++++++++++++++++++ arch/x86/Kconfig.assembler | 5 +++++ 2 files changed, 27 insertions(+)