X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=mm%2Fmprotect.c;h=60864e19421e6836997d8993239d0943d8787731;hb=HEAD;hp=ec39f730a0bfeebcd1d04ec34c5955f48a6f5259;hpb=0fd2e9c53d82704a3ba87ea1980ec515188c5316;p=mirror_ubuntu-bionic-kernel.git

diff --git a/mm/mprotect.c b/mm/mprotect.c
index ec39f730a0bf..60864e19421e 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -166,7 +166,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 		next = pmd_addr_end(addr, end);
 		if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
 				&& pmd_none_or_clear_bad(pmd))
-			continue;
+			goto next;
 
 		/* invoke the mmu notifier if the pmd is populated */
 		if (!mni_start) {
@@ -188,7 +188,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 					}
 
 					/* huge pmd was handled */
-					continue;
+					goto next;
 				}
 			}
 			/* fall through, the trans huge pmd just split */
@@ -196,6 +196,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
 				 dirty_accountable, prot_numa);
 		pages += this_pages;
+next:
+		cond_resched();
 	} while (pmd++, addr = next, addr != end);
 
 	if (mni_start)
@@ -290,6 +292,42 @@ 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)
@@ -307,6 +345,19 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 		return 0;
 	}
 
+	/*
+	 * 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