fanotify: add API to attach/detach super block mark

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>
Signed-off-by: Jan Kara <jack@suse.cz>

2 files changed, 49 insertions, 9 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 69054886915b..1347c588f778 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_MARK_TYPE_MASK;
         int ret;
 
         pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
@@ -817,6 +833,16 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 
         if (flags & ~FAN_ALL_MARK_FLAGS)
                 return -EINVAL;
+
+        switch (mark_type) {
+        case FAN_MARK_INODE:
+        case FAN_MARK_MOUNT:
+        case FAN_MARK_FILESYSTEM:
+                break;
+        default:
+                return -EINVAL;
+        }
+
         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
         case FAN_MARK_ADD:              /* fallthrough */
         case FAN_MARK_REMOVE:
@@ -824,7 +850,7 @@ 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_MARK_TYPE_MASK | FAN_MARK_FLUSH))
                         return -EINVAL;
                 break;
         default:
@@ -863,8 +889,10 @@ 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 +903,7 @@ 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 +911,18 @@ 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..ad81234d1919 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -27,7 +27,7 @@
 #define FAN_CLOEXEC             0x00000001
 #define FAN_NONBLOCK            0x00000002
 
-/* These are NOT bitwise flags.  Both bits are used togther.  */
+/* These are NOT bitwise flags.  Both bits are used together.  */
 #define FAN_CLASS_NOTIF         0x00000000
 #define FAN_CLASS_CONTENT       0x00000004
 #define FAN_CLASS_PRE_CONTENT   0x00000008
@@ -47,19 +47,27 @@
 #define FAN_MARK_REMOVE         0x00000002
 #define FAN_MARK_DONT_FOLLOW    0x00000004
 #define FAN_MARK_ONLYDIR        0x00000008
-#define FAN_MARK_MOUNT          0x00000010
+/* FAN_MARK_MOUNT is            0x00000010 */
 #define FAN_MARK_IGNORED_MASK   0x00000020
 #define FAN_MARK_IGNORED_SURV_MODIFY    0x00000040
 #define FAN_MARK_FLUSH          0x00000080
+/* FAN_MARK_FILESYSTEM is       0x00000100 */
+
+/* These are NOT bitwise flags.  Both bits can be used togther.  */
+#define FAN_MARK_INODE          0x00000000
+#define FAN_MARK_MOUNT          0x00000010
+#define FAN_MARK_FILESYSTEM     0x00000100
+#define FAN_MARK_TYPE_MASK      (FAN_MARK_INODE | FAN_MARK_MOUNT | \
+                                 FAN_MARK_FILESYSTEM)
 
 #define FAN_ALL_MARK_FLAGS      (FAN_MARK_ADD |\
                                  FAN_MARK_REMOVE |\
                                  FAN_MARK_DONT_FOLLOW |\
                                  FAN_MARK_ONLYDIR |\
-                                 FAN_MARK_MOUNT |\
                                  FAN_MARK_IGNORED_MASK |\
                                  FAN_MARK_IGNORED_SURV_MODIFY |\
-                                 FAN_MARK_FLUSH)
+                                 FAN_MARK_FLUSH|\
+                                 FAN_MARK_TYPE_MASK)
 
 /*
  * All of the events - we build the list by hand so that we can add flags in