From: Dis McCarthy <dmcrypt@sigkill.net>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] Strange header corruption
Date: Wed, 26 Feb 2014 10:24:38 -0500 [thread overview]
Message-ID: <CAHU=mb9qL-t+5nZi28yQ6VnKS6u9w9uBTU4kyVKx40jRok8_Zg@mail.gmail.com> (raw)
In-Reply-To: <20140226124939.GA26351@tansi.org>
[-- Attachment #1.1: Type: text/plain, Size: 9251 bytes --]
On Wed, Feb 26, 2014 at 7:49 AM, Arno Wagner <arno@wagner.name> wrote:
> On Wed, Feb 26, 2014 at 13:13:30 CET, Dis McCarthy wrote:
> > Thanks for the help!
> >
> > Unfortunately I don't have 7T to back up the devices. Is there a
> relatively
> > safe way to test? Worst case, I can make the change, set the entire
> device
> > ro and try, if dm-crypt can decrypt a readonly device.
>
> There is: Copy the first 100MB or so (needed are something like 2MiB, but
> better be on the safe side) and work on that via loopback file
> (see FAQ Item 2.5). When you can unlock that, you have then a good
> header that you can backup the header from the loopback device and
> install on the disk via luksHeaderBackup/luksHeaderRestore. Keep a
> copy of those first 100MB as backup on a separate device so you can
> restore it and can go back to the original state if anything goes
> wrong. This does protect your (at the moment broken, but nonetheless
> vital) headers from errors. Unlike a full backup, it does not protect
> your filesystem in the LUKS container(s), so be careful.
>
> If you are unsure, test disk operations first on a separate disk
> and see what they do to make sure you have it under control.
>
> You need to do that for each disk separately. If you cannot get an
> unlock, you can run the keyslot-checker on the loopback device
> as well and do further analysis there. All that LUKS needs is in
> the first 2MiB, see alos FAQ Item 6.12.
>
>
Those changes did result in a viewable/dumpable header, but it still won't
unlock.
Keyslot checker on both images returns:
parameters (commandline and LUKS header):
sector size: 512
threshold: 0.900000
- processing keyslot 0: start: 0x001000 end: 0x03f800
- processing keyslot 1: keyslot not in use
- processing keyslot 2: keyslot not in use
- processing keyslot 3: keyslot not in use
- processing keyslot 4: keyslot not in use
- processing keyslot 5: keyslot not in use
- processing keyslot 6: keyslot not in use
- processing keyslot 7: keyslot not in use
> > I did confirm farther down the header, the keys and empty slots appear
> to
> > be present.
>
> "Present" is not enough. "Undamaged" is what you need. But
> lets fix the missing bytes first and see where that gets
> you.
>
>
Definitely. Appearances can be deceiving. (And in this case, it looks like
they are.)
The complete/corrected headers are attached.
Thanks so much for helping!
> Arno
>
>
> > On Feb 25, 2014 11:11 PM, "Arno Wagner" <arno@wagner.name> wrote:
> > >
> > > This is pretty strange. You seem to have lost parts of the
> > > header, but not the hash spec. And it seems to have happened
> > > two times.
> > >
> > > This should not be happening at all. LUKS does not require a
> > > "clean shutdown", unless you luksFormat or change
> > > passphrases, cryptsetup does not write anything at all for
> > > LUKS and even ripping out the disk directly while it
> > > runs should not cause any header damage. (It may damage the
> > > filesystem in the LUKS container though...).
> > >
> > > What seems to have happened here is that some application
> > > read the header, replaced the first 0x2d bytes (leaving
> > > "ain64" of "xts-plain64". It seem to have put in a GUID
> > > of sorts. I have no idea what this is. The header was not
> > > simply overwritten, so this is something deliberately.
> > > On the other hand, no application should write anything to
> > > the start of a partition in normal operation.
> > >
> > > Maybe somebody else here recognizes the pattern seen?
> > > Maybe these are SSDs with a serious firmware bug?
> > > Or maybe you have wrap-around because the USB3 interface
> > > cannot handle the full disk size?
> > >
> > >
> > > As to recovery:
> > > 1. Make a sector-wise backup of the whole LUKS containers
> > > or whole disk(s) before messing with anything!
> > > 2. Just putting in what should be there in the first
> > > 0x2d bytes with a hex editor may be enough to get this
> > > working again if there is no other damage. If there
> > > is damage in the keyslot areas or to the salt values
> > > in the header, no recovery is possible.
> > >
> > > Hexediting the header is pretty simple, just read the
> > > first 1024 bytes (head -c 1024 /dev/disk > hdr.img),
> > > hexedit it and then write it back (cat hdr.img > /dev/disk).
> > > The risk of doing more damage is high, so do not try this
> > > without that backup.
> > >
> > > Here is what the first 0x2d bytes should look like (defaul
> > > parameters):
> > >
> > > 00000000 4c 55 4b 53 ba be 00 01 61 65 73 00 00 00 00 00
> > |LUKS....aes.....|
> > > 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > |................|
> > > 00000020 00 00 00 00 00 00 00 00 78 74 73 2d 70 6c 61 69
> > |........xts-plai|
> > >
> > > If after that cryptsetup works, but does not accept
> > > your passphrase, you can run the keyslot-checker from
> > > the source package and you can post the full headers
> > > (592 bytes long) here for more advice.
> > >
> > > Arno
> > >
> > >
> > >
> > >
> > >
> > > On Tue, Feb 25, 2014 at 15:33:20 CET, Dis McCarthy wrote:
> > > > I've got 2 full-device luks devices (usb3) that somehow got corrupted
> > > > headers at the same time. They were working, I powered down the
> system
> > to
> > > > move some plugs and when I brought it back up, my headers are
> > unrecognized.
> > > > (See below.) The system is a mac mini running arch linux. It has been
> > > > rebooted and powercycled repeatedly since being built and never had
> an
> > > > issue, so I hesitate to blame refit. The only thing I can see is that
> > there
> > > > was a recent update of cryptsetup (to 1.6.3-2). I'm not sure if the
> > devices
> > > > were stopped cleanly before reboot (probably not, since its arch..)
> but
> > the
> > > > volumes were unmounted and I wouldn't expect to get corruption.
> > > >
> > > > I'm dumb, and do not have a backup of the headers. (Well.. there
> might
> > be a
> > > > backup of one of them. Inside the encrypted volume.. yeah, like I
> said,
> > I'm
> > > > dumb. If I get this back, that is getting remedied immediately..)
> > > >
> > > > Comparing with other users, it looks like some of the entries are
> > swapped
> > > > around. I started doing a comparison to the on-disk format pdf, but I
> > > > haven't had a chance to print it out and get intimate with it yet
> > (beyond
> > > > noting that LUKS 0xba0xbe is missing of course.)
> > > >
> > > > Is there any hope? Here is what I've got at the beginning the drives:
> > > >
> > > > 00000000 00 00 00 00 48 00 00 00 00 00 00 00 32 32 30 64
> > > > |....H.......220d|
> > > > 00000010 32 30 33 64 2d 39 62 62 34 2d 34 35 00 00 00 00
> > > > |203d-9bb4-45....|
> > > > 00000020 24 00 00 00 12 00 00 00 24 00 00 00 00 00 61 69
> > > > |$.......$.....ai|
> > > > 00000030 6e 36 34 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > > |n64.............|
> > > > 00000040 00 00 00 00 00 00 00 00 73 68 61 32 35 36 00 00
> > > > |........sha256..|
> > > > 00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > > |................|
> > > > 00000060 00 00 00 00 00 00 00 00 00 00 10 00 00 00 00 40
> > > > |...............@|
> > > > 00000070 da 22 00 00 00 00 24 01 00 00 00 00 00 00 00 00
> > > > |."....$.........|
> > > >
> > > > and:
> > > > 00000000 00 00 00 00 48 00 00 00 00 00 00 00 32 33 63 38
> > > > |....H.......23c8|
> > > > 00000010 62 61 33 31 2d 37 61 63 66 2d 34 32 00 00 00 00
> > > > |ba31-7acf-42....|
> > > > 00000020 24 00 00 00 12 00 00 00 24 00 00 00 00 00 61 69
> > > > |$.......$.....ai|
> > > > 00000030 6e 36 34 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > > |n64.............|
> > > > 00000040 00 00 00 00 00 00 00 00 73 68 61 32 35 36 00 00
> > > > |........sha256..|
> > > > 00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > > > |................|
> > > > 00000060 00 00 00 00 00 00 00 00 00 00 10 00 00 00 00 40
> > > > |...............@|
> > > > 00000070 de 8b 00 00 00 00 24 01 00 00 00 00 00 00 00 00
> > > > |......$.........|
> > > >
> > > > Thanks!
> > >
> > > > _______________________________________________
> > > > dm-crypt mailing list
> > > > dm-crypt@saout.de
> > > > http://www.saout.de/mailman/listinfo/dm-crypt
> > >
> > >
> > > --
> > > Arno Wagner, Dr. sc. techn., Dipl. Inform., Email:
> arno@wagner.name
> > > GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D
> > 9718
> > > ----
> > > A good decision is based on knowledge and not on numbers. - Plato
> > > _______________________________________________
> > > dm-crypt mailing list
> > > dm-crypt@saout.de
> > > http://www.saout.de/mailman/listinfo/dm-crypt
>
> > _______________________________________________
> > dm-crypt mailing list
> > dm-crypt@saout.de
> > http://www.saout.de/mailman/listinfo/dm-crypt
>
>
> --
> Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name
> GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718
> ----
> A good decision is based on knowledge and not on numbers. - Plato
> _______________________________________________
> dm-crypt mailing list
> dm-crypt@saout.de
> http://www.saout.de/mailman/listinfo/dm-crypt
>
[-- Attachment #1.2: Type: text/html, Size: 12797 bytes --]
[-- Attachment #2: luksheader-sdc.txt --]
[-- Type: text/plain, Size: 3011 bytes --]
00000000 4c 55 4b 53 ba be 00 01 61 65 73 00 00 00 00 00 |LUKS....aes.....|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020 00 00 00 00 00 00 00 00 78 74 73 2d 70 6c 61 69 |........xts-plai|
00000030 6e 36 34 00 00 00 00 00 00 00 00 00 00 00 00 00 |n64.............|
00000040 00 00 00 00 00 00 00 00 73 68 61 32 35 36 00 00 |........sha256..|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 00 00 00 00 00 00 00 00 10 00 00 00 00 40 |...............@|
00000070 de 8b 00 00 00 00 24 01 00 00 00 00 00 00 00 00 |......$.........|
00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000090 00 00 00 01 00 00 12 01 c3 00 80 00 2f 21 68 a8 |............/!h.|
000000a0 39 c4 f1 5d 00 01 3e d9 32 33 63 38 62 61 33 31 |9..]..>.23c8ba31|
000000b0 2d 37 61 63 66 2d 34 32 65 31 2d 61 63 31 66 2d |-7acf-42e1-ac1f-|
000000c0 64 30 65 31 38 66 34 32 39 38 32 65 00 00 00 00 |d0e18f42982e....|
000000d0 00 ac 71 f3 00 05 02 0d cc 13 e4 7d 28 92 49 f1 |..q........}(.I.|
000000e0 ac 89 7a a3 75 32 4d db 27 18 2d e1 93 9e 97 82 |..z.u2M.'.-.....|
000000f0 90 a6 e0 e7 7a 28 8c 0f 00 00 00 08 00 00 0f a0 |....z(..........|
00000100 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000120 00 00 00 00 00 00 00 00 00 00 02 00 00 00 0f a0 |................|
00000130 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000150 00 00 00 00 00 00 00 00 00 00 03 f8 00 00 0f a0 |................|
00000160 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000180 00 00 00 00 00 00 00 00 00 00 05 f0 00 00 0f a0 |................|
00000190 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001b0 00 00 00 00 00 00 00 00 00 00 07 e8 00 00 0f a0 |................|
000001c0 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001e0 00 00 00 00 00 00 00 00 00 00 09 e0 00 00 0f a0 |................|
000001f0 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000210 00 00 00 00 00 00 00 00 00 00 0b d8 00 00 0f a0 |................|
00000220 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000240 00 00 00 00 00 00 00 00 00 00 0d d0 00 00 0f a0 |................|
00000250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000260
[-- Attachment #3: luksheader-sdb.txt --]
[-- Type: text/plain, Size: 3011 bytes --]
00000000 4c 55 4b 53 ba be 00 01 61 65 73 00 00 00 00 00 |LUKS....aes.....|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020 00 00 00 00 00 00 00 00 78 74 73 2d 70 6c 61 69 |........xts-plai|
00000030 6e 36 34 00 00 00 00 00 00 00 00 00 00 00 00 00 |n64.............|
00000040 00 00 00 00 00 00 00 00 73 68 61 32 35 36 00 00 |........sha256..|
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000060 00 00 00 00 00 00 00 00 00 00 10 00 00 00 00 40 |...............@|
00000070 da 22 00 00 00 00 24 01 00 00 00 00 00 00 00 00 |."....$.........|
00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000090 00 00 00 01 00 00 12 01 c3 00 80 00 79 a3 4c be |............y.L.|
000000a0 4e 8c bc 93 00 01 47 a3 32 32 30 64 33 30 33 64 |N.....G.220d303d|
000000b0 2d 39 62 62 34 2d 34 35 31 36 2d 38 38 39 65 2d |-9bb4-4516-889e-|
000000c0 63 39 34 32 39 63 31 33 38 37 36 66 00 00 00 00 |c9429c13876f....|
000000d0 00 ac 71 f3 00 05 41 e4 0a d5 d5 92 47 f4 61 eb |..q...A.....G.a.|
000000e0 38 e0 05 57 87 34 9b e0 52 30 c9 16 21 a8 39 19 |8..W.4..R0..!.9.|
000000f0 8b cc 09 20 a1 d0 a0 c4 00 00 00 08 00 00 0f a0 |... ............|
00000100 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000120 00 00 00 00 00 00 00 00 00 00 02 00 00 00 0f a0 |................|
00000130 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000150 00 00 00 00 00 00 00 00 00 00 03 f8 00 00 0f a0 |................|
00000160 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000180 00 00 00 00 00 00 00 00 00 00 05 f0 00 00 0f a0 |................|
00000190 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001b0 00 00 00 00 00 00 00 00 00 00 07 e8 00 00 0f a0 |................|
000001c0 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000001e0 00 00 00 00 00 00 00 00 00 00 09 e0 00 00 0f a0 |................|
000001f0 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000210 00 00 00 00 00 00 00 00 00 00 0b d8 00 00 0f a0 |................|
00000220 00 00 de ad 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000240 00 00 00 00 00 00 00 00 00 00 0d d0 00 00 0f a0 |................|
00000250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000260
next prev parent reply other threads:[~2014-02-26 15:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-25 14:33 [dm-crypt] Strange header corruption Dis McCarthy
2014-02-26 4:11 ` Arno Wagner
2014-02-26 12:13 ` Dis McCarthy
2014-02-26 12:49 ` Arno Wagner
2014-02-26 15:24 ` Dis McCarthy [this message]
2014-02-26 16:52 ` Arno Wagner
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