mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys

[cascardo/linux.git] / arch / x86 / include / asm / mmu_context.h

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index bfd9b2a..19036cd 100644 (file)
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -275,4 +275,64 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
                mpx_notify_unmap(mm, vma, start, end);
 }
 
+static inline int vma_pkey(struct vm_area_struct *vma)
+{
+       u16 pkey = 0;
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+       unsigned long vma_pkey_mask = VM_PKEY_BIT0 | VM_PKEY_BIT1 |
+                                     VM_PKEY_BIT2 | VM_PKEY_BIT3;
+       pkey = (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
+#endif
+       return pkey;
+}
+
+static inline bool __pkru_allows_pkey(u16 pkey, bool write)
+{
+       u32 pkru = read_pkru();
+
+       if (!__pkru_allows_read(pkru, pkey))
+               return false;
+       if (write && !__pkru_allows_write(pkru, pkey))
+               return false;
+
+       return true;
+}
+
+/*
+ * We only want to enforce protection keys on the current process
+ * because we effectively have no access to PKRU for other
+ * processes or any way to tell *which * PKRU in a threaded
+ * process we could use.
+ *
+ * So do not enforce things if the VMA is not from the current
+ * mm, or if we are in a kernel thread.
+ */
+static inline bool vma_is_foreign(struct vm_area_struct *vma)
+{
+       if (!current->mm)
+               return true;
+       /*
+        * Should PKRU be enforced on the access to this VMA?  If
+        * the VMA is from another process, then PKRU has no
+        * relevance and should not be enforced.
+        */
+       if (current->mm != vma->vm_mm)
+               return true;
+
+       return false;
+}
+
+static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write)
+{
+       /* allow access if the VMA is not one from this process */
+       if (vma_is_foreign(vma))
+               return true;
+       return __pkru_allows_pkey(vma_pkey(vma), write);
+}
+
+static inline bool arch_pte_access_permitted(pte_t pte, bool write)
+{
+       return __pkru_allows_pkey(pte_flags_pkey(pte_flags(pte)), write);
+}
+
 #endif /* _ASM_X86_MMU_CONTEXT_H */