fanotify: hooks the fanotify_mark syscall to the vfsmount code

Create a new fanotify_mark flag which indicates we should attach the mark
to the vfsmount holding the object referenced by dfd and pathname rather
than the inode itself.

Signed-off-by: Eric Paris <eparis@redhat.com>

2 files changed, 14 insertions, 5 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index db80a0d89d24..81267260d1b9 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -485,7 +485,8 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
                               __u64 mask, int dfd,
                               const char  __user * pathname)
 {
-        struct inode *inode;
+        struct inode *inode = NULL;
+        struct vfsmount *mnt = NULL;
         struct fsnotify_group *group;
         struct file *filp;
         struct path path;
@@ -515,16 +516,22 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
                 goto fput_and_out;
 
         /* inode held in place by reference to path; group by fget on fd */
-        inode = path.dentry->d_inode;
+        if (!(flags & FAN_MARK_ON_VFSMOUNT))
+                inode = path.dentry->d_inode;
+        else
+                mnt = path.mnt;
         group = filp->private_data;
 
         /* create/update an inode mark */
         switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
         case FAN_MARK_ADD:
-                ret = fanotify_add_inode_mark(group, inode, mask);
+                if (flags & FAN_MARK_ON_VFSMOUNT)
+                        ret = fanotify_add_vfsmount_mark(group, mnt, mask);
+                else
+                        ret = fanotify_add_inode_mark(group, inode, mask);
                 break;
         case FAN_MARK_REMOVE:
-                ret = fanotify_remove_mark(group, inode, NULL, mask);
+                ret = fanotify_remove_mark(group, inode, mnt, mask);
                 break;
         default:
                 ret = -EINVAL;
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 5f633af4d1b0..e25d348188ca 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -29,11 +29,13 @@
 #define FAN_MARK_REMOVE         0x00000002
 #define FAN_MARK_DONT_FOLLOW    0x00000004
 #define FAN_MARK_ONLYDIR        0x00000008
+#define FAN_MARK_ON_VFSMOUNT    0x00000010
 
 #define FAN_ALL_MARK_FLAGS      (FAN_MARK_ADD |\
                                  FAN_MARK_REMOVE |\
                                  FAN_MARK_DONT_FOLLOW |\
-                                 FAN_MARK_ONLYDIR)
+                                 FAN_MARK_ONLYDIR |\
+                                 FAN_MARK_ON_VFSMOUNT)
 
 /*
  * All of the events - we build the list by hand so that we can add flags in