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SubjectRe: [PATCH v27 10/10] x86/vdso: Add ENDBR to __vdso_sgx_enter_enclave
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On 5/22/2021 3:47 PM, Jarkko Sakkinen wrote:
> On Fri, May 21, 2021 at 03:15:31PM -0700, Yu-cheng Yu wrote:
>> ENDBR is a special new instruction for the Indirect Branch Tracking (IBT)
>> component of CET. IBT prevents attacks by ensuring that (most) indirect
>> branches and function calls may only land at ENDBR instructions. Branches
>> that don't follow the rules will result in control flow (#CF) exceptions.
>>
>> ENDBR is a noop when IBT is unsupported or disabled. Most ENDBR
>> instructions are inserted automatically by the compiler, but branch
>> targets written in assembly must have ENDBR added manually.
>>
>> Add ENDBR to __vdso_sgx_enter_enclave() branch targets.
>>
>> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
>> Reviewed-by: Kees Cook <keescook@chromium.org>
>> Cc: Andy Lutomirski <luto@kernel.org>
>> Cc: Borislav Petkov <bp@alien8.de>
>> Cc: Dave Hansen <dave.hansen@linux.intel.com>
>> Cc: Jarkko Sakkinen <jarkko@kernel.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>
>
> Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
>
>> ---
>> arch/x86/entry/vdso/vsgx.S | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S
>> index 99dafac992e2..c7cb85d57b3f 100644
>> --- a/arch/x86/entry/vdso/vsgx.S
>> +++ b/arch/x86/entry/vdso/vsgx.S
>> @@ -4,6 +4,7 @@
>> #include <asm/export.h>
>> #include <asm/errno.h>
>> #include <asm/enclu.h>
>> +#include <asm/vdso.h>
>>
>> #include "extable.h"
>>
>> @@ -27,6 +28,7 @@
>> SYM_FUNC_START(__vdso_sgx_enter_enclave)
>> /* Prolog */
>> .cfi_startproc
>> + ENDBR64
>> push %rbp
>> .cfi_adjust_cfa_offset 8
>> .cfi_rel_offset %rbp, 0
>> @@ -62,6 +64,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave)
>> .Lasync_exit_pointer:
>> .Lenclu_eenter_eresume:
>> enclu
>> + ENDBR64
>>
>> /* EEXIT jumps here unless the enclave is doing something fancy. */
>> mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx
>> @@ -91,6 +94,7 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave)
>> jmp .Lout
>>
>> .Lhandle_exception:
>> + ENDBR64
>> mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx
>>
>> /* Set the exception info. */
>> --
>> 2.21.0
>>
>>
>
> /Jarkko
>

Thanks!

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