1 files changed, 22 insertions, 19 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 43f32ee9f95c..ae6d1312b184 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1197,10 +1197,7 @@ static void commit_tree(struct mount *mnt)
 
 	if (!mnt_ns_attached(mnt)) {
 		for (struct mount *m = mnt; m; m = next_mnt(m, mnt))
-			if (unlikely(mnt_ns_attached(m)))
-				m = skip_mnt_tree(m);
-			else
-				mnt_add_to_ns(n, m);
+			mnt_add_to_ns(n, m);
 		n->nr_mounts += n->pending_mounts;
 		n->pending_mounts = 0;
 	}
@@ -2704,6 +2701,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
 			lock_mnt_tree(child);
 		q = __lookup_mnt(&child->mnt_parent->mnt,
 				 child->mnt_mountpoint);
+		commit_tree(child);
 		if (q) {
 			struct mountpoint *mp = root.mp;
 			struct mount *r = child;
@@ -2713,7 +2711,6 @@ static int attach_recursive_mnt(struct mount *source_mnt,
 				mp = shorter;
 			mnt_change_mountpoint(r, mp, q);
 		}
-		commit_tree(child);
 	}
 	unpin_mountpoint(&root);
 	unlock_mount_hash();
@@ -2862,6 +2859,19 @@ static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
 	return attach_recursive_mnt(mnt, p, mp);
 }
 
+static int may_change_propagation(const struct mount *m)
+{
+        struct mnt_namespace *ns = m->mnt_ns;
+
+	 // it must be mounted in some namespace
+	 if (IS_ERR_OR_NULL(ns))         // is_mounted()
+		 return -EINVAL;
+	 // and the caller must be admin in userns of that namespace
+	 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+		 return -EPERM;
+	 return 0;
+}
+
 /*
  * Sanity check the flags to change_mnt_propagation.
  */
@@ -2898,10 +2908,10 @@ static int do_change_type(struct path *path, int ms_flags)
 		return -EINVAL;
 
 	namespace_lock();
-	if (!check_mnt(mnt)) {
-		err = -EINVAL;
+	err = may_change_propagation(mnt);
+	if (err)
 		goto out_unlock;
-	}
+
 	if (type == MS_SHARED) {
 		err = invent_group_ids(mnt, recurse);
 		if (err)
@@ -3347,18 +3357,11 @@ static int do_set_group(struct path *from_path, struct path *to_path)
 
 	namespace_lock();
 
-	err = -EINVAL;
-	/* To and From must be mounted */
-	if (!is_mounted(&from->mnt))
-		goto out;
-	if (!is_mounted(&to->mnt))
-		goto out;
-
-	err = -EPERM;
-	/* We should be allowed to modify mount namespaces of both mounts */
-	if (!ns_capable(from->mnt_ns->user_ns, CAP_SYS_ADMIN))
+	err = may_change_propagation(from);
+	if (err)
 		goto out;
-	if (!ns_capable(to->mnt_ns->user_ns, CAP_SYS_ADMIN))
+	err = may_change_propagation(to);
+	if (err)
 		goto out;
 
 	err = -EINVAL;