arm64: Support execute-only permissions with Enhanced PAN
Enhanced Privileged Access Never (EPAN) allows Privileged Access Never
to be used with Execute-only mappings.
Absence of such support was a reason for 24cecc377463 ("arm64: Revert
support for execute-only user mappings"). Thus now it can be revisited
and re-enabled.
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210312173811.58284-2-vladimir.murzin@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/mm/mmap.c b/mm/mmap.c
index 3f28759..1d96a21 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -93,6 +93,12 @@ static void unmap_region(struct mm_struct *mm,
* MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
* w: (no) no w: (no) no w: (copy) copy w: (no) no
* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
+ *
+ * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
+ * MAP_PRIVATE (with Enhanced PAN supported):
+ * r: (no) no
+ * w: (no) no
+ * x: (yes) yes
*/
pgprot_t protection_map[16] __ro_after_init = {
__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,