[PATCH v3 3/3] fanotify: add API to attach/detach super block mark

[Amir Goldstein <amir73il@gmail.com>]

Add another mark type flag FAN_MARK_FILESYSTEM for add/remove/flush
of super block mark type.

A super block watch gets all events on the filesystem, regardless of
the mount from which the mark was added, unless an ignore mask exists
on either the inode or the mount where the event was generated.

Only one of FAN_MARK_MOUNT and FAN_MARK_FILESYSTEM mark type flags
may be provided to fanotify_mark() or no mark type flag for inode mark.

Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/notify/fanotify/fanotify_user.c | 37 ++++++++++++++++++++++++++++++++-----
 include/uapi/linux/fanotify.h      |  7 ++++++-
 2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 69054886915b..dff64c7e75fd 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -563,6 +563,13 @@ static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
 				    mask, flags);
 }
 
+static int fanotify_remove_sb_mark(struct fsnotify_group *group,
+				      struct super_block *sb, __u32 mask,
+				      unsigned int flags)
+{
+	return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask, flags);
+}
+
 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
 				      struct inode *inode, __u32 mask,
 				      unsigned int flags)
@@ -658,6 +665,14 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
 				 FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags);
 }
 
+static int fanotify_add_sb_mark(struct fsnotify_group *group,
+				      struct super_block *sb, __u32 mask,
+				      unsigned int flags)
+{
+	return fanotify_add_mark(group, &sb->s_fsnotify_marks,
+				 FSNOTIFY_OBJ_TYPE_SB, mask, flags);
+}
+
 static int fanotify_add_inode_mark(struct fsnotify_group *group,
 				   struct inode *inode, __u32 mask,
 				   unsigned int flags)
@@ -806,6 +821,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	struct fd f;
 	struct path path;
 	u32 valid_mask = FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD;
+	unsigned int mark_type = flags & FAN_ALL_MARK_TYPE_FLAGS;
 	int ret;
 
 	pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
@@ -817,6 +833,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 
 	if (flags & ~FAN_ALL_MARK_FLAGS)
 		return -EINVAL;
+
+	/* mixed mark type flags are invalid */
+	if (mark_type && !is_power_of_2(mark_type))
+		return -EINVAL;
+
 	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
 	case FAN_MARK_ADD:		/* fallthrough */
 	case FAN_MARK_REMOVE:
@@ -824,7 +845,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 			return -EINVAL;
 		break;
 	case FAN_MARK_FLUSH:
-		if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH))
+		if (flags & ~(FAN_ALL_MARK_TYPE_FLAGS | FAN_MARK_FLUSH))
 			return -EINVAL;
 		break;
 	default:
@@ -863,8 +884,10 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 
 	if (flags & FAN_MARK_FLUSH) {
 		ret = 0;
-		if (flags & FAN_MARK_MOUNT)
+		if (mark_type == FAN_MARK_MOUNT)
 			fsnotify_clear_vfsmount_marks_by_group(group);
+		else if (mark_type == FAN_MARK_FILESYSTEM)
+			fsnotify_clear_sb_marks_by_group(group);
 		else
 			fsnotify_clear_inode_marks_by_group(group);
 		goto fput_and_out;
@@ -875,7 +898,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 		goto fput_and_out;
 
 	/* inode held in place by reference to path; group by fget on fd */
-	if (!(flags & FAN_MARK_MOUNT))
+	if (mark_type == FAN_MARK_INODE)
 		inode = path.dentry->d_inode;
 	else
 		mnt = path.mnt;
@@ -883,14 +906,18 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	/* create/update an inode mark */
 	switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
 	case FAN_MARK_ADD:
-		if (flags & FAN_MARK_MOUNT)
+		if (mark_type == FAN_MARK_MOUNT)
 			ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
+		else if (mark_type == FAN_MARK_FILESYSTEM)
+			ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask, flags);
 		else
 			ret = fanotify_add_inode_mark(group, inode, mask, flags);
 		break;
 	case FAN_MARK_REMOVE:
-		if (flags & FAN_MARK_MOUNT)
+		if (mark_type == FAN_MARK_MOUNT)
 			ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
+		else if (mark_type == FAN_MARK_FILESYSTEM)
+			ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask, flags);
 		else
 			ret = fanotify_remove_inode_mark(group, inode, mask, flags);
 		break;
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 74247917de04..7345b9a57f66 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -43,6 +43,7 @@
 				 FAN_UNLIMITED_MARKS)
 
 /* flags used for fanotify_modify_mark() */
+#define FAN_MARK_INODE		0x00000000
 #define FAN_MARK_ADD		0x00000001
 #define FAN_MARK_REMOVE		0x00000002
 #define FAN_MARK_DONT_FOLLOW	0x00000004
@@ -51,6 +52,7 @@
 #define FAN_MARK_IGNORED_MASK	0x00000020
 #define FAN_MARK_IGNORED_SURV_MODIFY	0x00000040
 #define FAN_MARK_FLUSH		0x00000080
+#define FAN_MARK_FILESYSTEM	0x00000100
 
 #define FAN_ALL_MARK_FLAGS	(FAN_MARK_ADD |\
 				 FAN_MARK_REMOVE |\
@@ -59,7 +61,10 @@
 				 FAN_MARK_MOUNT |\
 				 FAN_MARK_IGNORED_MASK |\
 				 FAN_MARK_IGNORED_SURV_MODIFY |\
-				 FAN_MARK_FLUSH)
+				 FAN_MARK_FLUSH|\
+				 FAN_MARK_FILESYSTEM)
+
+#define FAN_ALL_MARK_TYPE_FLAGS (FAN_MARK_MOUNT | FAN_MARK_FILESYSTEM)
 
 /*
  * All of the events - we build the list by hand so that we can add flags in
-- 
2.7.4