From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCCCCC31E45 for ; Thu, 13 Jun 2019 16:11:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90DB620679 for ; Thu, 13 Jun 2019 16:11:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560442311; bh=PH6dG94hNLWF7W1sTLFFWbqMCAI3bu5OdGA+wHUVEiA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JnjjcsK6aH3iOAXd6yu148D22waEU+2GSaZo7/l2ZkHU9K3nhIxW1KL+tAtj60rhU WLEW9xoeUJQQBGDJVyCWL1uYO8osRbUedCPkIYjrVl81g59qYTv0IysyoWDdU+bmkX eXqMQT+G/z6EZRHaSOZajqESHk/fEcic+MXSbHdI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391389AbfFMQLV (ORCPT ); Thu, 13 Jun 2019 12:11:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:60720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731242AbfFMInd (ORCPT ); Thu, 13 Jun 2019 04:43:33 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7B9AF2147A; Thu, 13 Jun 2019 08:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560415413; bh=PH6dG94hNLWF7W1sTLFFWbqMCAI3bu5OdGA+wHUVEiA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tDAX8zpQNngusszD0XcthOBBZ28+2UfSSU/YjkFws+72+EucQrLbHjLFU39AA0j1j Q6nry/WXOT5F/w4ejCc1gJOUGLP5v/J70Gp4QCfiEnk++hyOsanVrnd4Som62t5bTu eBdVvJZvhYHFd6y2IPzeZvRyJheetsuh/UMsPE7I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiufei Xue , Miklos Szeredi , Amir Goldstein Subject: [PATCH 4.19 116/118] ovl: check the capability before cred overridden Date: Thu, 13 Jun 2019 10:34:14 +0200 Message-Id: <20190613075651.066987620@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190613075643.642092651@linuxfoundation.org> References: <20190613075643.642092651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jiufei Xue commit 98487de318a6f33312471ae1e2afa16fbf8361fe upstream. We found that it return success when we set IMMUTABLE_FL flag to a file in docker even though the docker didn't have the capability CAP_LINUX_IMMUTABLE. The commit d1d04ef8572b ("ovl: stack file ops") and dab5ca8fd9dd ("ovl: add lsattr/chattr support") implemented chattr operations on a regular overlay file. ovl_real_ioctl() overridden the current process's subjective credentials with ofs->creator_cred which have the capability CAP_LINUX_IMMUTABLE so that it will return success in vfs_ioctl()->cap_capable(). Fix this by checking the capability before cred overridden. And here we only care about APPEND_FL and IMMUTABLE_FL, so get these information from inode. [SzM: move check and call to underlying fs inside inode locked region to prevent two such calls from racing with each other] Signed-off-by: Jiufei Xue Signed-off-by: Miklos Szeredi Cc: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/file.c | 79 ++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 61 insertions(+), 18 deletions(-) --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "overlayfs.h" static char ovl_whatisit(struct inode *inode, struct inode *realinode) @@ -372,10 +373,68 @@ static long ovl_real_ioctl(struct file * return ret; } -static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +static unsigned int ovl_get_inode_flags(struct inode *inode) +{ + unsigned int flags = READ_ONCE(inode->i_flags); + unsigned int ovl_iflags = 0; + + if (flags & S_SYNC) + ovl_iflags |= FS_SYNC_FL; + if (flags & S_APPEND) + ovl_iflags |= FS_APPEND_FL; + if (flags & S_IMMUTABLE) + ovl_iflags |= FS_IMMUTABLE_FL; + if (flags & S_NOATIME) + ovl_iflags |= FS_NOATIME_FL; + + return ovl_iflags; +} + +static long ovl_ioctl_set_flags(struct file *file, unsigned long arg) { long ret; struct inode *inode = file_inode(file); + unsigned int flags; + unsigned int old_flags; + + if (!inode_owner_or_capable(inode)) + return -EACCES; + + if (get_user(flags, (int __user *) arg)) + return -EFAULT; + + ret = mnt_want_write_file(file); + if (ret) + return ret; + + inode_lock(inode); + + /* Check the capability before cred override */ + ret = -EPERM; + old_flags = ovl_get_inode_flags(inode); + if (((flags ^ old_flags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) && + !capable(CAP_LINUX_IMMUTABLE)) + goto unlock; + + ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY); + if (ret) + goto unlock; + + ret = ovl_real_ioctl(file, FS_IOC_SETFLAGS, arg); + + ovl_copyflags(ovl_inode_real(inode), inode); +unlock: + inode_unlock(inode); + + mnt_drop_write_file(file); + + return ret; + +} + +static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + long ret; switch (cmd) { case FS_IOC_GETFLAGS: @@ -383,23 +442,7 @@ static long ovl_ioctl(struct file *file, break; case FS_IOC_SETFLAGS: - if (!inode_owner_or_capable(inode)) - return -EACCES; - - ret = mnt_want_write_file(file); - if (ret) - return ret; - - ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY); - if (!ret) { - ret = ovl_real_ioctl(file, cmd, arg); - - inode_lock(inode); - ovl_copyflags(ovl_inode_real(inode), inode); - inode_unlock(inode); - } - - mnt_drop_write_file(file); + ret = ovl_ioctl_set_flags(file, arg); break; default: