From: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
This adds special handling for revoked memory mappings. We want to raise
SIGBUS when accessing revoked mappings and return ENODEV when trying to remap
with mmap(2).
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
---
include/linux/mm.h | 1 +
mm/memory.c | 3 +++
mm/mmap.c | 12 ++++++++----
3 files changed, 12 insertions(+), 4 deletions(-)
Index: 2.6/include/linux/mm.h
===================================================================
--- 2.6.orig/include/linux/mm.h 2007-07-06 10:19:51.000000000 +0300
+++ 2.6/include/linux/mm.h 2007-07-11 11:48:28.000000000 +0300
@@ -169,6 +169,7 @@ #define VM_NONLINEAR 0x00800000 /* Is no
#define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu mmap) */
#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
#define VM_ALWAYSDUMP 0x04000000 /* Always include in core dumps */
+#define VM_REVOKED 0x08000000 /* Mapping has been revoked */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
Index: 2.6/mm/memory.c
===================================================================
--- 2.6.orig/mm/memory.c 2007-07-06 10:19:53.000000000 +0300
+++ 2.6/mm/memory.c 2007-07-11 11:48:28.000000000 +0300
@@ -2597,6 +2597,9 @@ int __handle_mm_fault(struct mm_struct *
if (unlikely(is_vm_hugetlb_page(vma)))
return hugetlb_fault(mm, vma, address, write_access);
+ if (unlikely(vma->vm_flags & VM_REVOKED))
+ return VM_FAULT_SIGBUS;
+
pgd = pgd_offset(mm, address);
pud = pud_alloc(mm, pgd, address);
if (!pud)
Index: 2.6/mm/mmap.c
===================================================================
--- 2.6.orig/mm/mmap.c 2007-07-06 10:19:53.000000000 +0300
+++ 2.6/mm/mmap.c 2007-07-11 11:48:28.000000000 +0300
@@ -1031,10 +1031,14 @@ accountable = 0;
error = -ENOMEM;
munmap_back:
vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
- if (vma && vma->vm_start < addr + len) {
- if (do_munmap(mm, addr, len))
- return -ENOMEM;
- goto munmap_back;
+ if (vma) {
+ if (unlikely(vma->vm_flags & VM_REVOKED))
+ return -ENODEV;
+ if (vma->vm_start < addr + len) {
+ if (do_munmap(mm, addr, len))
+ return -ENOMEM;
+ goto munmap_back;
+ }
}
/* Check against address space limit. */
-
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