Re: [RFC v4 03/17] x86: key creation with PKEY_DISABLE_EXECUTE disallowed

[Balbir Singh]

On Tue, 2017-06-27 at 03:11 -0700, Ram Pai wrote:
> x86 does not support disabling execute permissions on a pkey.
> 
> Signed-off-by: Ram Pai 
> ---
>  arch/x86/kernel/fpu/xstate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index c24ac1e..d582631 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -900,6 +900,9 @@ int arch_set_user_pkey_access(struct task_struct *tsk, 
> int pkey,
>   if (!boot_cpu_has(X86_FEATURE_OSPKE))
>   return -EINVAL;
>  
> + if (init_val & PKEY_DISABLE_EXECUTE)
> + return -EINVAL;
> +
>   /* Set the bits we need in PKRU:  */
>   if (init_val & PKEY_DISABLE_ACCESS)
>   new_pkru_bits |= PKRU_AD_BIT;

I am not an x86 expert. IIUC, execute disable is done via allocating an
execute_only_pkey and checking vma_key via AD + vma_flags against VM_EXEC.

Your patch looks good to me

Acked-by: Balbir Singh 

Balbir Singh.

[RFC v4 03/17] x86: key creation with PKEY_DISABLE_EXECUTE disallowed

[Ram Pai]

x86 does not support disabling execute permissions on a pkey.

Signed-off-by: Ram Pai 
---
 arch/x86/kernel/fpu/xstate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index c24ac1e..d582631 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -900,6 +900,9 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int 
pkey,
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return -EINVAL;
 
+   if (init_val & PKEY_DISABLE_EXECUTE)
+   return -EINVAL;
+
/* Set the bits we need in PKRU:  */
if (init_val & PKEY_DISABLE_ACCESS)
new_pkru_bits |= PKRU_AD_BIT;
-- 
1.8.3.1