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/mm | |
| parent | 7419333fa15ec958d12845fcc79b7bdd16de06ec (diff) | |
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/mm')
| -rw-r--r-- | arch/arm64/mm/fault.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 05d2bd776c69..a5f098a5f602 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -251,8 +251,7 @@ static int __do_page_fault(struct mm_struct *mm, unsigned long addr, good_area: /* * Check that the permissions on the VMA allow for the fault which - * occurred. If we encountered a write or exec fault, we must have - * appropriate permissions, otherwise we allow any permission. + * occurred. */ if (!(vma->vm_flags & vm_flags)) { fault = VM_FAULT_BADACCESS; @@ -288,7 +287,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, struct task_struct *tsk; struct mm_struct *mm; int fault, sig, code; - unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC; + unsigned long vm_flags = VM_READ | VM_WRITE; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; if (notify_page_fault(regs, esr)) |