summaryrefslogtreecommitdiffstats
path: root/mm/mprotect.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/mprotect.c')
-rw-r--r--mm/mprotect.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 625608bc8962..6d331620b9e5 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -306,6 +306,42 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
return pages;
}
+static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
+ 0 : -EACCES;
+}
+
+static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
+ unsigned long addr, unsigned long next,
+ struct mm_walk *walk)
+{
+ return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
+ 0 : -EACCES;
+}
+
+static int prot_none_test(unsigned long addr, unsigned long next,
+ struct mm_walk *walk)
+{
+ return 0;
+}
+
+static int prot_none_walk(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long newflags)
+{
+ pgprot_t new_pgprot = vm_get_page_prot(newflags);
+ struct mm_walk prot_none_walk = {
+ .pte_entry = prot_none_pte_entry,
+ .hugetlb_entry = prot_none_hugetlb_entry,
+ .test_walk = prot_none_test,
+ .mm = current->mm,
+ .private = &new_pgprot,
+ };
+
+ return walk_page_range(start, end, &prot_none_walk);
+}
+
int
mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
unsigned long start, unsigned long end, unsigned long newflags)
@@ -324,6 +360,19 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
}
/*
+ * Do PROT_NONE PFN permission checks here when we can still
+ * bail out without undoing a lot of state. This is a rather
+ * uncommon case, so doesn't need to be very optimized.
+ */
+ if (arch_has_pfn_modify_check() &&
+ (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
+ (newflags & (VM_READ|VM_WRITE|VM_EXEC)) == 0) {
+ error = prot_none_walk(vma, start, end, newflags);
+ if (error)
+ return error;
+ }
+
+ /*
* If we make a private mapping writable we increase our commit;
* but (without finer accounting) cannot reduce our commit if we
* make it unwritable again. hugetlb mapping were accounted for