[vlc-devel] [PATCH] configure: enable ARMv8.3 Pointer Authentication

[Thomas Guillem]

On Tue, Jul 9, 2019, at 21:12, Rémi Denis-Courmont wrote:
> If the compiler supports the the dedicated code generation command line

nit: the the

> flag, use it to provide return/backward control flow integrity (CFI).
> 
> This provides protection against return-oriented programming attacks on
> where supported. This has no effects if the processor and/or operating
> system do not support the extension, except for adding no-ops in the
> generated machine code.
> 
> So far the AArch64 assembler code in VLC is only made of leaf functions
> which do not not store/load the link register value, so there are no
> needs to use the Pointer Authentication instructions manually (at least
> not for return-CFI).

OK for me.

> ---
>  configure.ac | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index b48124d810..534b5886f7 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -1682,6 +1682,18 @@ asm volatile("ptrue p0.s" ::: "p0");
>  ])
>  AM_CONDITIONAL([HAVE_SVE], [test "${ac_cv_arm_sve}" = "yes"])
>  
> +AC_ARG_ENABLE([pointer-auth],
> +  AS_HELP_STRING([--disable-pointer-auth],
> +    [disable ARMv8.3 Pointer Authentication (default auto)]),, [
> +  AS_IF([test "${host_cpu}" = "aarch64"], [enable_ptrauth="yes"] 
> ,[enable_ptrauth="no"])
> +])
> +AS_IF([test "${enable_ptrauth}" != "no"], [
> +  AX_CHECK_COMPILE_FLAG([-msign-return-address=non-leaf], [
> +    AX_APPEND_FLAG([-msign-return-address=non-leaf], [CFLAGS])
> +    AX_APPEND_FLAG([-msign-return-address=non-leaf], [CXXFLAGS])
> +  ])
> +])
> +
>  
>  AC_ARG_ENABLE([altivec],
>    AS_HELP_STRING([--disable-altivec],
> -- 
> 2.20.1
> 
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