fanotify: clear all fanotify marks

fanotify listeners may want to clear all marks.  They may want to do this
to destroy all of their inode marks which have nothing but ignores.
Realistically this is useful for av vendors who update policy and want to
clear all of their cached allows.
Signed-off-by: Eric Paris <eparis@redhat.com>

fs/notify/fanotify/fanotify_user.c

@@ -514,9 +514,10 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 
 	if (flags & ~FAN_ALL_MARK_FLAGS)
 		return -EINVAL;
-	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
+	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 	case FAN_MARK_ADD:
 	case FAN_MARK_REMOVE:
+	case FAN_MARK_FLUSH:
 		break;
 	default:
 		return -EINVAL;
@@ -545,7 +546,7 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 	group = filp->private_data;
 
 	/* create/update an inode mark */
-	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
+	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 	case FAN_MARK_ADD:
 		if (flags & FAN_MARK_MOUNT)
 			ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
@@ -558,6 +559,13 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
 		else
 			ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 		break;
+	case FAN_MARK_FLUSH:
+		if (flags & FAN_MARK_MOUNT)
+			fsnotify_clear_vfsmount_marks_by_group(group);
+		else
+			fsnotify_clear_inode_marks_by_group(group);
+		fsnotify_recalc_group_mask(group);
+		break;
 	default:
 		ret = -EINVAL;
 	}

fs/notify/inode_mark.c

@@ -103,6 +103,14 @@ void fsnotify_clear_marks_by_inode(struct inode *inode)
 	}
 }
 
+/*
+ * Given a group clear all of the inode marks associated with that group.
+ */
+void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
+{
+	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
+}
+
 /*
  * given a group and inode, find the mark associated with that combination.
  * if found take a reference to that mark and return it, else return NULL

fs/notify/mark.c

@@ -270,18 +270,21 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
 }
 
 /*
- * Given a group, destroy all of the marks associated with that group.
+ * clear any marks in a group in which mark->flags & flags is true
  */
-void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
+void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
+					 unsigned int flags)
 {
 	struct fsnotify_mark *lmark, *mark;
 	LIST_HEAD(free_list);
 
 	spin_lock(&group->mark_lock);
 	list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
-		list_add(&mark->free_g_list, &free_list);
-		list_del_init(&mark->g_list);
-		fsnotify_get_mark(mark);
+		if (mark->flags & flags) {
+			list_add(&mark->free_g_list, &free_list);
+			list_del_init(&mark->g_list);
+			fsnotify_get_mark(mark);
+		}
 	}
 	spin_unlock(&group->mark_lock);
 
@@ -291,6 +294,14 @@ void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
 	}
 }
 
+/*
+ * Given a group, destroy all of the marks associated with that group.
+ */
+void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
+{
+	fsnotify_clear_marks_by_group_flags(group, (unsigned int)-1);
+}
+
 void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old)
 {
 	assert_spin_locked(&old->lock);

fs/notify/vfsmount_mark.c

@@ -51,6 +51,11 @@ void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
 	}
 }
 
+void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
+{
+	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
+}
+
 /*
  * Recalculate the mask of events relevant to a given vfsmount locked.
  */

include/linux/fanotify.h

@@ -32,6 +32,7 @@
 #define FAN_MARK_MOUNT		0x00000010
 #define FAN_MARK_IGNORED_MASK	0x00000020
 #define FAN_MARK_IGNORED_SURV_MODIFY	0x00000040
+#define FAN_MARK_FLUSH		0x00000080
 
 #define FAN_ALL_MARK_FLAGS	(FAN_MARK_ADD |\
 				 FAN_MARK_REMOVE |\

include/linux/fsnotify_backend.h

@@ -384,6 +384,12 @@ extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *
 			     struct inode *inode, struct vfsmount *mnt, int allow_dups);
 /* given a mark, flag it to be freed when all references are dropped */
 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark);
+/* run all the marks in a group, and clear all of the vfsmount marks */
+extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
+/* run all the marks in a group, and clear all of the inode marks */
+extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
+/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
+extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
 /* run all the marks in a group, and flag them to be freed */
 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
 extern void fsnotify_get_mark(struct fsnotify_mark *mark);