[dm-crypt] Initializing dm-crypt on Android results in "device lookup failed"

Roman Schlegel lists at ione.ch
Sun May 22 11:31:17 CEST 2016


I am currently trying to track down an issue with dm-crypt on an Android
device (more specifically, I am building a CM 12.1 ROM), where
initializing device encryption fails with an error.

I have asked this question in a number of other places as well
(stackoverflow and xda), but have not gotten any responses. I therefore
decided to ask the question on a list more directly connected to
dm-crypt. It is if course entirely possible that the error lies
somewhere in the device-mapper, but in that case my hope is still that
somebody on this list is familiar enough with the device-mapper and its
interaction with dm-crypt to point me to a potential solution.

So here is the problem: when starting the device encryption, the
encryption itself fails with the following error:

01-01 03:20:02.631 I/Cryptfs (  254): Using scrypt for cryptfs KDF

01-01 03:20:03.592 I/Cryptfs (  254): Enabling support for
allow_discards in dmcrypt.

01-01 03:20:03.592 I/Cryptfs (  254): load_crypto_mapping_table:
target_type = crypt

01-01 03:20:03.592 I/Cryptfs (  254): load_crypto_mapping_table:
real_blk_name = /dev/block/platform/mtk-msdc.0/by-name/userdata,
extra_params = 1 allow_discards

01-01 03:20:03.592 I/Cryptfs (  254): load_crypto_mapping_table:
crypt_params = aes-cbc-essiv:sha256 0A66F89B0D3DFC0B05D9BD23B3453A70 0
/dev/block/platform/mtk-msdc.0/by-name/userdata 0 1 allow_discards 0

01-01 03:20:08.619 E/Cryptfs (  254): Cannot load dm-crypt mapping table.

at the same time, the kernel log prints the following messages:

<3>[  138.163773] (5)[327:vold]device-mapper: table: 253:0: crypt:
Device lookup failed
<4>[  138.163781] (5)[327:vold]device-mapper: ioctl: error adding target
to table

Unfortunately, the device I am testing this with has not had the kernel
sources released, so I only have a prebuilt kernel (3.10.61) that I
cannot recompile. However, another ROM using the same kernel (IIRC) can
successfully encrypt the device, so I don't think it is anything
inherent in the kernel itself. But I am at a loss what else could be the

I'd be happy to provide any additional information as needed.

Any help or pointers in solving this issue would be greatly appreciated.

Best regards,


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