4 files changed, 38 insertions, 0 deletions
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index caa36cb9c46d..ce7c3aba61e4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -279,3 +279,6 @@ int ovl_copy_up(struct dentry *dentry);
 int ovl_copy_up_flags(struct dentry *dentry, int flags);
 int ovl_copy_xattr(struct dentry *old, struct dentry *new);
 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+		       const char *name, const void *value, size_t size,
+		       int xerr);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index b2023ddb8532..ad86c0a302eb 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -28,6 +28,7 @@ struct ovl_fs {
 	/* creds of process who forced instantiation of super block */
 	const struct cred *creator_cred;
 	bool tmpfile;
+	bool noxattr;
 	wait_queue_head_t copyup_wq;
 	/* sb common to all layers */
 	struct super_block *same_sb;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 9828b7de8999..f1647626a882 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -891,6 +891,19 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 				dput(temp);
 			else
 				pr_warn("overlayfs: upper fs does not support tmpfile.\n");
+
+			/*
+			 * Check if upper/work fs supports trusted.overlay.*
+			 * xattr
+			 */
+			err = ovl_do_setxattr(ufs->workdir, OVL_XATTR_OPAQUE,
+					      "0", 1, 0);
+			if (err) {
+				ufs->noxattr = true;
+				pr_warn("overlayfs: upper fs does not support xattr.\n");
+			} else {
+				vfs_removexattr(ufs->workdir, OVL_XATTR_OPAQUE);
+			}
 		}
 	}
 
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index cfdea47313a1..b5a0dc36ee96 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -303,3 +303,24 @@ void ovl_copy_up_end(struct dentry *dentry)
 	wake_up_locked(&ofs->copyup_wq);
 	spin_unlock(&ofs->copyup_wq.lock);
 }
+
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+		       const char *name, const void *value, size_t size,
+		       int xerr)
+{
+	int err;
+	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+	if (ofs->noxattr)
+		return xerr;
+
+	err = ovl_do_setxattr(upperdentry, name, value, size, 0);
+
+	if (err == -EOPNOTSUPP) {
+		pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
+		ofs->noxattr = true;
+		return xerr;
+	}
+
+	return err;
+}