Re: [PATCH v7 40/41] x86/shstk: Add ARCH_SHSTK_UNLOCK
From: Borislav Petkov <bp@alien8.de>
Date: 2023-03-11 15:11:38
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On Mon, Feb 27, 2023 at 02:29:56PM -0800, Rick Edgecombe wrote:
From: Mike Rapoport <redacted> 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 <redacted> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <redacted> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
That tag is kinda implicit here. Unless he doesn't ACK his own patch. :-P
Reviewed-by: Kees Cook <redacted> Signed-off-by: Mike Rapoport <redacted> [Merged into recent API changes, added commit log and docs] Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
...
quoted hunk ↗ jump to hunk
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