[RFC][Patch 5/6] integrity: mtime patch for mmap files

[Mimi Zohar]

This is a minimal subset of Peter Staubach's July patch, updated to
apply to the latest kernel. The subset was chosen to demonstrate that
mmaped files are hashed and hmac properly by EVM after being modified
when a file's mtime is updated correctly.

Index: linux-2.6.21-rc3-mm2/fs/inode.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/fs/inode.c
+++ linux-2.6.21-rc3-mm2/fs/inode.c
@@ -1209,8 +1209,8 @@ void touch_atime(struct vfsmount *mnt, s
 EXPORT_SYMBOL(touch_atime);
 
 /**
- *	file_update_time	-	update mtime and ctime time
- *	@file: file accessed
+ *	inode_update_time	-	update mtime and ctime time
+ *	@inode: file accessed
  *
  *	Update the mtime and ctime members of an inode and mark the inode
  *	for writeback.  Note that this function is meant exclusively for
@@ -1220,9 +1220,8 @@ EXPORT_SYMBOL(touch_atime);
  *	timestamps are handled by the server.
  */
 
-void file_update_time(struct file *file)
+void inode_update_time(struct inode *inode)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
 	struct timespec now;
 	int sync_it = 0;
 
@@ -1246,7 +1245,7 @@ void file_update_time(struct file *file)
 		mark_inode_dirty_sync(inode);
 }
 
-EXPORT_SYMBOL(file_update_time);
+EXPORT_SYMBOL(inode_update_time);
 
 int inode_needs_sync(struct inode *inode)
 {
Index: linux-2.6.21-rc3-mm2/fs/fs-writeback.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/fs/fs-writeback.c
+++ linux-2.6.21-rc3-mm2/fs/fs-writeback.c
@@ -167,6 +167,9 @@ __sync_single_inode(struct inode *inode,
 
 	spin_unlock(&inode_lock);
 
+	if (test_and_clear_bit(AS_MCTIME, &mapping->flags))
+		inode_update_time(inode);
+
 	ret = do_writepages(mapping, wbc);
 
 	/* Don't write the inode if only I_DIRTY_PAGES was set */
Index: linux-2.6.21-rc3-mm2/fs/buffer.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/fs/buffer.c
+++ linux-2.6.21-rc3-mm2/fs/buffer.c
@@ -734,8 +734,11 @@ int __set_page_dirty_buffers(struct page
 	}
 	spin_unlock(&mapping->private_lock);
 
-	if (TestSetPageDirty(page))
+	if (TestSetPageDirty(page)) {
+		if (page_mapped(page))
+			set_bit(AS_MCTIME, &mapping->flags);
 		return 0;
+	}
 
 	write_lock_irq(&mapping->tree_lock);
 	if (page->mapping) {	/* Race with truncate? */
@@ -749,6 +752,8 @@ int __set_page_dirty_buffers(struct page
 	}
 	write_unlock_irq(&mapping->tree_lock);
 	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+	if (page_mapped(page))
+		set_bit(AS_MCTIME, &mapping->flags);
 	return 1;
 }
 EXPORT_SYMBOL(__set_page_dirty_buffers);
Index: linux-2.6.21-rc3-mm2/include/linux/fs.h
===================================================================
--- linux-2.6.21-rc3-mm2.orig/include/linux/fs.h
+++ linux-2.6.21-rc3-mm2/include/linux/fs.h
@@ -1944,7 +1944,12 @@ extern int buffer_migrate_page(struct ad
 extern int inode_change_ok(struct inode *, struct iattr *);
 extern int __must_check inode_setattr(struct inode *, struct iattr *);
 
-extern void file_update_time(struct file *file);
+extern void inode_update_time(struct inode *);
+
+static inline void file_update_time(struct file *file)
+{
+	inode_update_time(file->f_dentry->d_inode);
+}
 
 static inline ino_t parent_ino(struct dentry *dentry)
 {
Index: linux-2.6.21-rc3-mm2/include/linux/pagemap.h
===================================================================
--- linux-2.6.21-rc3-mm2.orig/include/linux/pagemap.h
+++ linux-2.6.21-rc3-mm2/include/linux/pagemap.h
@@ -17,8 +17,9 @@
  * Bits in mapping->flags.  The lower __GFP_BITS_SHIFT bits are the page
  * allocation mode flags.
  */
-#define	AS_EIO		(__GFP_BITS_SHIFT + 0)	/* IO error on async write */
+#define AS_EIO		(__GFP_BITS_SHIFT + 0)	/* IO error on async write */
 #define AS_ENOSPC	(__GFP_BITS_SHIFT + 1)	/* ENOSPC on async write */
+#define AS_MCTIME	(__GFP_BITS_SHIFT + 2)	/* need m/ctime change */
 
 static inline void mapping_set_error(struct address_space *mapping, int error)
 {
Index: linux-2.6.21-rc3-mm2/mm/page-writeback.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/mm/page-writeback.c
+++ linux-2.6.21-rc3-mm2/mm/page-writeback.c
@@ -815,8 +815,10 @@ int __set_page_dirty_no_writeback(struct
  */
 int __set_page_dirty_nobuffers(struct page *page)
 {
+	struct address_space *mapping = page_mapping(page);
+	int ret = 0;
+
 	if (!TestSetPageDirty(page)) {
-		struct address_space *mapping = page_mapping(page);
 		struct address_space *mapping2;
 
 		if (!mapping)
@@ -840,9 +842,11 @@ int __set_page_dirty_nobuffers(struct pa
 			/* !PageAnon && !swapper_space */
 			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 		}
-		return 1;
+		ret = 1;
 	}
-	return 0;
+	if (page_mapped(page))
+		set_bit(AS_MCTIME, &mapping->flags);
+	return ret;
 }
 EXPORT_SYMBOL(__set_page_dirty_nobuffers);
 



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