diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2014-04-03 16:17:32 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2014-05-09 15:53:36 +0100 |
| commit | bc07c2c6e9ed125d362af0214b6313dca180cb08 (patch) | |
| tree | a5a63f1272c11e321999145b8b7e8135b094aaaa /arch/arm64 | |
| parent | 15af1942dd61ee236a48b3de14d6f31c0b9e8116 (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. 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')
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 11 | ||||
| -rw-r--r-- | arch/arm64/mm/fault.c | 5 |
2 files changed, 8 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 90c811f05a2e..e50bb3cbd8f2 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -90,6 +90,7 @@ extern pgprot_t pgprot_default; #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) #endif /* __ASSEMBLY__ */ @@ -97,7 +98,7 @@ extern pgprot_t pgprot_default; #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 @@ -106,7 +107,7 @@ extern pgprot_t pgprot_default; #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 @@ -143,8 +144,8 @@ extern struct page *empty_zero_page; #define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE)) #define pte_exec(pte) (!(pte_val(pte) & PTE_UXN)) -#define pte_valid_user(pte) \ - ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) +#define pte_valid_ng(pte) \ + ((pte_val(pte) & (PTE_VALID | PTE_NG)) == (PTE_VALID | PTE_NG)) static inline pte_t pte_wrprotect(pte_t pte) { @@ -198,7 +199,7 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr); static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte) { - if (pte_valid_user(pte)) { + if (pte_valid_ng(pte)) { if (!pte_special(pte) && pte_exec(pte)) __sync_icache_dcache(pte, addr); if (pte_dirty(pte) && pte_write(pte)) 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; |