[RFC PATCH v2 5/8] mm: kpkeys: Introduce cred pkey/level

[Kevin Brodsky]

We will need a separate pkey to protect struct cred. Allocate one as
well as a new kpkeys level that grants write access to that pkey.

Signed-off-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>
---
 arch/arm64/include/asm/kpkeys.h | 7 ++++++-
 include/asm-generic/kpkeys.h    | 4 ++++
 include/linux/kpkeys.h          | 3 ++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h
index ded5d6e988dc..ffb7622391c3 100644
--- a/arch/arm64/include/asm/kpkeys.h
+++ b/arch/arm64/include/asm/kpkeys.h
@@ -13,7 +13,8 @@
  * used in assembly.
  */
 #define POR_EL1_INIT	(POR_ELx_PERM_PREP(KPKEYS_PKEY_DEFAULT, POE_RWX) | \
-			 POR_ELx_PERM_PREP(KPKEYS_PKEY_PGTABLES, POE_R))
+			 POR_ELx_PERM_PREP(KPKEYS_PKEY_PGTABLES, POE_R) | \
+			 POR_ELx_PERM_PREP(KPKEYS_PKEY_CRED, POE_R))
 
 #ifndef __ASSEMBLY__
 
@@ -31,6 +32,10 @@ static inline u64 por_set_kpkeys_level(u64 por, int level)
 				     level == KPKEYS_LVL_PGTABLES ||
 				     level == KPKEYS_LVL_UNRESTRICTED
 				     ? POE_RW : POE_R);
+	por = por_elx_set_pkey_perms(por, KPKEYS_PKEY_CRED,
+				     level == KPKEYS_LVL_CRED ||
+				     level == KPKEYS_LVL_UNRESTRICTED
+				     ? POE_RW : POE_R);
 
 	return por;
 }
diff --git a/include/asm-generic/kpkeys.h b/include/asm-generic/kpkeys.h
index cec92334a9f3..56a2fc9fe4a6 100644
--- a/include/asm-generic/kpkeys.h
+++ b/include/asm-generic/kpkeys.h
@@ -2,6 +2,10 @@
 #ifndef __ASM_GENERIC_KPKEYS_H
 #define __ASM_GENERIC_KPKEYS_H
 
+#ifndef KPKEYS_PKEY_CRED
+#define KPKEYS_PKEY_CRED	2
+#endif
+
 #ifndef KPKEYS_PKEY_PGTABLES
 #define KPKEYS_PKEY_PGTABLES	1
 #endif
diff --git a/include/linux/kpkeys.h b/include/linux/kpkeys.h
index 48f240bea8e1..0e555b505b33 100644
--- a/include/linux/kpkeys.h
+++ b/include/linux/kpkeys.h
@@ -10,7 +10,8 @@ struct folio;
 
 #define KPKEYS_LVL_DEFAULT	0
 #define KPKEYS_LVL_PGTABLES	1
-#define KPKEYS_LVL_UNRESTRICTED	2
+#define KPKEYS_LVL_CRED		2
+#define KPKEYS_LVL_UNRESTRICTED	3
 
 #define KPKEYS_LVL_MIN		KPKEYS_LVL_DEFAULT
 #define KPKEYS_LVL_MAX		KPKEYS_LVL_UNRESTRICTED
-- 
2.47.0