[dm-crypt] openLuks failing - semaphore weird bug involved ?

Ric Flomag ricflomag at gmail.com
Wed Sep 7 20:30:32 CEST 2011


Hi all,

I've been using an external usb hard drive with three (no LVM)  partitions,
one of them crypt-luks (set up using palimpsest), for months. It used to get
auto-mounted under Gnome when plugged. Seahorse provided the key (Ubuntu
11.04).

Since a few days ago, it does not mount anymore. luksOpen yields a "no key
available" error message. No one around me can be suspected to have changed
the password. The other (plain ext4) partition mounts normally.

I can backup or dump the header without a problem. Another usb hardrive,
with the same luks setup (as shown by header dumps), mounts as usual. All
this is reproducible on other systems (another ubuntu 11.04 and a 11.10
beta).

Note that I have the "weird semaphore bug" described here:
http://thread.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/5237/focus=5243,
though, in my case:
  * it happens approx. once every three luksOpen attempts
  * It is not related to luksOpen success or failure (the semaphore error
message is just displayed sometimes with any of both hard drives)
  * Chromium is not involved

Coincidentally, I have started to use my hard drives with ubuntu 11.00 beta
a few days ago. It could have messed up something on one hd and not the
other?

Any hint to try and fix this ?

------------- faulty partition
LUKS header information for /dev/sdb3

Version:           1
Cipher name:       aes
Cipher mode:       cbc-essiv:sha256
Hash spec:         sha1
Payload offset:    2056
MK bits:           256
MK digest:         70 41 d4 78 bd 91 9e 82 c3 9c 61 df e8 6b 4e 28 2f 2b 90
94
MK salt:           a8 c6 7f 6f 35 2b 48 19 cc e7 27 7a 4f a6 ca a3
                   9f 78 6d f8 21 b0 48 56 44 27 2c 53 75 bf 0c 86
MK iterations:     22875
UUID:              4b74a5b1-0c46-4808-98c0-3a51ec5f7c8e

Key Slot 0: ENABLED
    Iterations:             91811
    Salt:                   24 f0 44 14 a7 4d ae e6 b6 2b 42 7c 8d 10 87 39
                              47 05 fd 35 14 46 62 12 f7 5a 7e 99 8a 67 33
f5
    Key material offset:    8
    AF stripes:                4000
Key Slot 1: DISABLED
Key Slot 2: DISABLED
Key Slot 3: DISABLED
Key Slot 4: DISABLED
Key Slot 5: DISABLED
Key Slot 6: DISABLED
Key Slot 7: DISABLED
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