Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757328AbdLWDas (ORCPT ); Fri, 22 Dec 2017 22:30:48 -0500 Received: from h2.hallyn.com ([78.46.35.8]:53908 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757161AbdLWDap (ORCPT ); Fri, 22 Dec 2017 22:30:45 -0500 Date: Fri, 22 Dec 2017 21:30:44 -0600 From: "Serge E. Hallyn" To: Dongsu Park Cc: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, Alban Crequy , "Eric W . Biederman" , Miklos Szeredi , Seth Forshee , Sargun Dhillon , linux-fsdevel@vger.kernel.org, Alexander Viro , Serge Hallyn Subject: Re: [PATCH 05/11] fs: Allow superblock owner to access do_remount_sb() Message-ID: <20171223033044.GE6837@mail.hallyn.com> References: <8dd484dceb9e96e5b67f21b8a0cf333753985e89.1512041070.git.dongsu@kinvolk.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8dd484dceb9e96e5b67f21b8a0cf333753985e89.1512041070.git.dongsu@kinvolk.io> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1807 Lines: 49 On Fri, Dec 22, 2017 at 03:32:29PM +0100, Dongsu Park wrote: > From: Seth Forshee > > Superblock level remounts are currently restricted to global > CAP_SYS_ADMIN, as is the path for changing the root mount to > read only on umount. Loosen both of these permission checks to > also allow CAP_SYS_ADMIN in any namespace which is privileged > towards the userns which originally mounted the filesystem. > > Patch v4 is available: https://patchwork.kernel.org/patch/8944631/ > > Cc: linux-fsdevel@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: Alexander Viro > Cc: "Eric W. Biederman" > Cc: Serge Hallyn Acked-by: Serge Hallyn > Signed-off-by: Seth Forshee > Signed-off-by: Dongsu Park > --- > fs/namespace.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index e158ec6b..830040d7 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -1589,7 +1589,7 @@ static int do_umount(struct mount *mnt, int flags) > * Special case for "unmounting" root ... > * we just try to remount it readonly. > */ > - if (!capable(CAP_SYS_ADMIN)) > + if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) > return -EPERM; > down_write(&sb->s_umount); > if (!sb_rdonly(sb)) > @@ -2327,7 +2327,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, > down_write(&sb->s_umount); > if (ms_flags & MS_BIND) > err = change_mount_flags(path->mnt, ms_flags); > - else if (!capable(CAP_SYS_ADMIN)) > + else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) > err = -EPERM; > else > err = do_remount_sb(sb, sb_flags, data, 0); > -- > 2.13.6