From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.mailbox.org ([80.241.60.215]:29084 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S971002AbeEXP6K (ORCPT ); Thu, 24 May 2018 11:58:10 -0400 Date: Thu, 24 May 2018 17:58:03 +0200 From: Christian Brauner To: "Eric W. Biederman" Cc: Linux Containers , linux-kernel@vger.kernel.org, Seth Forshee , linux-fsdevel@vger.kernel.org Subject: Re: [REVIEW][PATCH 4/6] fs: Allow superblock owner to access do_remount_sb() Message-ID: <20180524155803.GB19932@mailbox.org> References: <87o9h6554f.fsf@xmission.com> <20180523232538.4880-4-ebiederm@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180523232538.4880-4-ebiederm@xmission.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, May 23, 2018 at 06:25:36PM -0500, Eric W. Biederman wrote: > 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. Acked-by: Christian Brauner > > Signed-off-by: Seth Forshee > Acked-by: "Eric W. Biederman" > Acked-by: Serge Hallyn Note, I just talked to Serge. This should be Acked-by: Serge Hallyn > Signed-off-by: Eric W. Biederman > --- > fs/namespace.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index 5f75969adff1..8ddd14806799 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -1590,7 +1590,7 @@ 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)) > @@ -2333,7 +2333,7 @@ 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); > -- > 2.14.1 > > _______________________________________________ > Containers mailing list > Containers@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/containers