diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2014-04-03 19:17:32 +0400 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2014-05-09 18:53:36 +0400 |
| commit | bc07c2c6e9ed125d362af0214b6313dca180cb08 (patch) | |
| tree | a5a63f1272c11e321999145b8b7e8135b094aaaa /arch/arm64/mm/fault.c | |
| parent | 15af1942dd61ee236a48b3de14d6f31c0b9e8116 (diff) | |
| download | linux-bc07c2c6e9ed125d362af0214b6313dca180cb08.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. The kernel, however, 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
implement/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_valid_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_valid_ng() macro. VM_READ is also checked now for page faults.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm/fault.c')
| -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 bcc965e2cce1..89c6763d5e7e 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -173,8 +173,7 @@ 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; @@ -196,7 +195,7 @@ 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; tsk = current; |