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@xxxxxxxxx> > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Andy Lutomirski <luto@xxxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Acked-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > --- > 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
