On Mon, Feb 27, 2023 at 02:29:56PM -0800, Rick Edgecombe wrote:
> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
>
> Userspace loaders may lock features before a CRIU restore operation has
> the chance to set them to whatever state is required by the process
> being restored. Allow a way for CRIU to unlock features. Add it as an
> arch_prctl() like the other shadow stack operations, but restrict it being
> called by the ptrace arch_pctl() interface.
>
> Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
> Tested-by: John Allen <john.allen@xxxxxxx>
> Tested-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
That tag is kinda implicit here. Unless he doesn't ACK his own patch.
:-P
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> [Merged into recent API changes, added commit log and docs]
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
...
> diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
> index 2faf9b45ac72..3197ff824809 100644
> --- a/arch/x86/kernel/shstk.c
> +++ b/arch/x86/kernel/shstk.c
> @@ -451,9 +451,14 @@ long shstk_prctl(struct task_struct *task, int option, unsigned long features)
> return 0;
> }
>
> - /* Don't allow via ptrace */
> - if (task != current)
> + /* Only allow via ptrace */
> + if (task != current) {
Is that the only case? task != current means ptrace and there's no other
way to do this from userspace?
Isn't there some flag which says that task is ptraced? I think we should
check that one too...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
