[tip: x86/shstk] x86/shstk: Wire in shadow stack interface

[tip-bot2 for Rick Edgecombe]

The following commit has been merged into the x86/shstk branch of tip:

Commit-ID:     d463cfe241f0ea4194f3575b4d28fd744db321f1
Gitweb:        https://git.kernel.org/tip/d463cfe241f0ea4194f3575b4d28fd744db321f1
Author:        Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
AuthorDate:    Mon, 12 Jun 2023 17:11:03 -07:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Thu, 15 Jun 2023 16:31:34 -07:00

x86/shstk: Wire in shadow stack interface

The kernel now has the main shadow stack functionality to support
applications. Wire in the WRSS and shadow stack enable/disable functions
into the existing shadow stack API skeleton.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
Tested-by: John Allen <john.allen@xxxxxxx>
Tested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20230613001108.3040476-38-rick.p.edgecombe%40intel.com
---
 arch/x86/kernel/shstk.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index ea0bf11..d723cdc 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -502,9 +502,17 @@ long shstk_prctl(struct task_struct *task, int option, unsigned long features)
 		return -EINVAL;
 
 	if (option == ARCH_SHSTK_DISABLE) {
+		if (features & ARCH_SHSTK_WRSS)
+			return wrss_control(false);
+		if (features & ARCH_SHSTK_SHSTK)
+			return shstk_disable();
 		return -EINVAL;
 	}
 
 	/* Handle ARCH_SHSTK_ENABLE */
+	if (features & ARCH_SHSTK_SHSTK)
+		return shstk_setup();
+	if (features & ARCH_SHSTK_WRSS)
+		return wrss_control(true);
 	return -EINVAL;
 }