From: Theodore Ts'o Subject: Re: GRUB and the risk of block list corruption in extX Date: Sat, 9 Feb 2013 23:45:55 -0500 Message-ID: <20130210044555.GD8526@thunk.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-ext4@vger.kernel.org To: Chris Murphy Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:47664 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761083Ab3BJEp6 (ORCPT ); Sat, 9 Feb 2013 23:45:58 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, Feb 09, 2013 at 05:17:58PM -0700, Chris Murphy wrote: > On the other hand=E2=80=A6 >=20 > > There are some folks who are proposing that we use a bootloader ino= de: > > for grub's benefit.=20 >=20 > Who are requesting this? If not GRUB's devs, it would seem there are > other developers who are also paranoid. Well, it was one of the participants (or observers) of=20 https://bugzilla.redhat.com/show_bug.cgi?id=3D872826 He posted on the linux-ext4 list a week or so ago: http://comments.gmane.org/gmane.comp.file-systems.ext4/36637 > > But it's not something that has been terribly high priority, since > > it's basically more of a security blanket for the grub2 developers > > more than anything else=E2=80=A6. >=20 > It may be a security blanket for grub2 developers. However, it > appears to me users want a security blanket also. Well, a participant of on the redhat bugzilla inquired about it. If someone wants to send me some patches, I'm happy to review them. I personally think it's not a great use of time, but that's the wonderful thing about open source. You can always send patches. :-) > Despite my bias against two bootloaders (I think it's ridiculous, > but then I prefer 1/2 a boot loader), the question I have is if a > blocklist is really needed to find and load the 2nd boot loader? > Because needing a blocklist in the VBR implies the first boot loader > doesn't understand ext(4). If true, before engineering file system > changes, users need to upgrade their ancient primary boot loader. It's been a long time since I really spent a lot of time studying grub, but my understanding is that the first boot loader (which fits in the MBR) is just too small to have room to understand the ext[234] file system; you can't really do a lot in 492 bytes of x86 assembly..... That's why it uses a block list instead. But honestly, I really don't care a whole lot about the emotional insecurity of the grub2 developers, and if distributions are worried about their users being insecure, they can always comment out the alarmist message in grub2. Or they can send me patches. :-) - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html