Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753035AbdGYTVu (ORCPT ); Tue, 25 Jul 2017 15:21:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34452 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752973AbdGYTVo (ORCPT ); Tue, 25 Jul 2017 15:21:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Konstantin Khlebnikov , Vivek Goyal , Miklos Szeredi , Amir Goldstein Subject: [PATCH 4.9 074/125] ovl: drop CAP_SYS_RESOURCE from saved mounters credentials Date: Tue, 25 Jul 2017 12:19:49 -0700 Message-Id: <20170725192018.397990862@linuxfoundation.org> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170725192014.314851996@linuxfoundation.org> References: <20170725192014.314851996@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1679 Lines: 53 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 51f8f3c4e22535933ef9aecc00e9a6069e051b57 upstream. If overlay was mounted by root then quota set for upper layer does not work because overlay now always use mounter's credentials for operations. Also overlay might deplete reserved space and inodes in ext4. This patch drops capability SYS_RESOURCE from saved credentials. This affects creation new files, whiteouts, and copy-up operations. Signed-off-by: Konstantin Khlebnikov Fixes: 1175b6b8d963 ("ovl: do operations on underlying file system in mounter's context") Cc: Vivek Goyal Signed-off-by: Miklos Szeredi Cc: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/super.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1146,6 +1146,7 @@ static int ovl_fill_super(struct super_b unsigned int stacklen = 0; unsigned int i; bool remote = false; + struct cred *cred; int err; err = -ENOMEM; @@ -1309,10 +1310,13 @@ static int ovl_fill_super(struct super_b else sb->s_d_op = &ovl_dentry_operations; - ufs->creator_cred = prepare_creds(); - if (!ufs->creator_cred) + ufs->creator_cred = cred = prepare_creds(); + if (!cred) goto out_put_lower_mnt; + /* Never override disk quota limits or use reserved space */ + cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); + err = -ENOMEM; oe = ovl_alloc_entry(numlower); if (!oe)