| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Tue, 19 Feb 2013 22:15:37 +0100
From: "Dr. Tilmann Bubeck" <t.bubeck@...nform.de>
To: unlisted-recipients:; (no To-header on input)
CC: linux-ext4@...r.kernel.org
Subject: Re: Use EXT4_BOOT_LOADER_INO for boot loader GRUB?
Ted,
my previous email contains a first implementation of your idea. Did I
get it right or do you want me something to change?
I can also offer some shell scripts for mass testing the change to a
fresh ext4 filesystem to ensure, that it does not break anything. I ran
the script and indeed it does not break anything (as far as I can see).
Kind regards,
Tilmann
Am 26.01.2013 19:49, schrieb Theodore Ts'o:
> On Fri, Jan 25, 2013 at 09:18:50AM +0100, Dr. Tilmann Bubeck wrote:
>> The basic problem is, that GRUB needs a safe place to store
>> (currently 32k) for its boot loader "core.img". That place should be
>> simple to find from the primary boot code ("stage1") and the place
>> should be safe for user intervention.
>>
>> QUESTION:
>>
>> You have reserved a special inode #5 called "EXT4_BOOT_LOADER_INO".
>> Is this inode currently used or supported by kernel or user land?
>> What is the idea of this inode?
>
> It was basically for something exactly like this. :-)
>
>> PROPOSAL:
>>
>> I can think of using that inode to store the file "core.img" of
>> GRUB. That file is used by GRUB to boot and the block list of that
>> file is stored in GRUB when using "--force" to override the above
>> error.
>>
>> ext2/3/4 must make sure, that the block list of that file never
>> changes. I propose an additional EXT4 ioctl to tell ext4, which file
>> to store in EXT4_BOOT_LOADER_INO.
>
> What I'm thinking about is a new ioctl that would swap the i_block and
> i_blocks array of the BOOT_LOADER_INO and the file descriptor. That
> is, if there were any blocks attached to the boot_loader_ino, they
> would become attached to the inode associated with the file
> descriptor, and the blocks associated with that inode would be
> attached to inode #5.
>
>> Probably there must be more changes to e2fsck and friends.
>
> Actually, no changes to e2fsck would be necessary. The original plan
> was that boot loader inode would be installed while the file system is
> unmounted. But it's already the case that blocks associated with
> inode <5> are already accounted for by e2fsck.
>
> - Ted
>
--
+-------+-------------------------------------------------------------+
| | dr. tilmann bubeck reinform medien- und |
| | informationstechnologie AG |
| rein | fon : +49 (711) 7 82 76-52 loeffelstr. 40 |
| form | fax : +49 (711) 7 82 76-46 70597 stuttgart / germany |
| AG | cell.: +49 (172) 8 84 29 72 fon: +49 (711) 75 86 56-10 |
| | email: t.bubeck@...nform.de http://www.reinform.de |
| +-------------------------------------------------------------+
| | pflichtangaben nach paragraph 80, AktG: |
| | reinform medien- und informationstechnologie AG, stuttgart |
| | handelsregister stuttgart, HRB 23001 |
| | vorstand: dr. tilmann bubeck (vorsitz) |
| | aufsichtsrat: frank stege (vorsitz) |
+-------+-------------------------------------------------------------+
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists