[dm-crypt] Strange header corruption

Dis McCarthy dmcrypt at sigkill.net
Tue Feb 25 15:33:20 CET 2014


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!
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