diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-08-11 20:44:50 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-08-25 20:00:29 +0300 |
| commit | cab15ce604e550020bb7115b779013b91bcdbc21 (patch) | |
| tree | 0ba025b8ad16505532aaa6e1b4cc665473f026fa /mm | |
| parent | 7419333fa15ec958d12845fcc79b7bdd16de06ec (diff) | |
| download | linux-cab15ce604e550020bb7115b779013b91bcdbc21.tar.xz | |
arm64: Introduce execute-only page access permissions
The ARMv8 architecture allows execute-only user permissions by clearing
the PTE_UXN and PTE_USER bits. However, the kernel running on a CPU
implementation without User Access Override (ARMv8.2 onwards) can still
access such page, so execute-only page permission does not protect
against read(2)/write(2) etc. accesses. Systems requiring such
protection must enable features like SECCOMP.
This patch changes the arm64 __P100 and __S100 protection_map[] macros
to the new __PAGE_EXECONLY attributes. A side effect is that
pte_user() no longer triggers for __PAGE_EXECONLY since PTE_USER isn't
set. To work around this, the check is done on the PTE_NG bit via the
pte_ng() macro. VM_READ is also checked now for page faults.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mmap.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index ca9d91bca0d6..69cad562cd00 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -88,6 +88,11 @@ static void unmap_region(struct mm_struct *mm, * 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: + * r: (no) no + * w: (no) no + * x: (yes) yes */ pgprot_t protection_map[16] = { __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, |