diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-08-11 18:44:50 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-08-25 18:00:29 +0100 |
| commit | cab15ce604e550020bb7115b779013b91bcdbc21 (patch) | |
| tree | 0ba025b8ad16505532aaa6e1b4cc665473f026fa /arch/arm64/include/asm/pgtable-prot.h | |
| parent | 7419333fa15ec958d12845fcc79b7bdd16de06ec (diff) | |
| download | linux-cab15ce604e550020bb7115b779013b91bcdbc21.tar.bz2 | |
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 'arch/arm64/include/asm/pgtable-prot.h')
| -rw-r--r-- | arch/arm64/include/asm/pgtable-prot.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 39f5252673f7..2142c7726e76 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -70,12 +70,13 @@ #define PAGE_COPY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN) #define PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN) #define PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN) +#define PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_NG | PTE_PXN) #define __P000 PAGE_NONE #define __P001 PAGE_READONLY #define __P010 PAGE_COPY #define __P011 PAGE_COPY -#define __P100 PAGE_READONLY_EXEC +#define __P100 PAGE_EXECONLY #define __P101 PAGE_READONLY_EXEC #define __P110 PAGE_COPY_EXEC #define __P111 PAGE_COPY_EXEC @@ -84,7 +85,7 @@ #define __S001 PAGE_READONLY #define __S010 PAGE_SHARED #define __S011 PAGE_SHARED -#define __S100 PAGE_READONLY_EXEC +#define __S100 PAGE_EXECONLY #define __S101 PAGE_READONLY_EXEC #define __S110 PAGE_SHARED_EXEC #define __S111 PAGE_SHARED_EXEC |