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

Roman Schlegel lists at ione.ch
Mon May 23 21:50:11 CEST 2016


Hi,

On 23.05.2016 21:17, Roman Schlegel wrote:
> Hi Milan,
> 
> Thanks a lot for your reply.
> 
> On 23.05.2016 11:04, Milan Broz wrote:
>> On 05/22/2016 11:31 AM, Roman Schlegel wrote:
>>> Hello,
>>>
>>> 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.
>>
>> ...
>>
>>> 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
>>
>> I really hope Android does not log volume key such a way to system log...
>>
> 
> No, it doesn't :-). That's the testing output I added to vold to check
> that it wasn't a problem with the parameters submitted to dm-crypt.
> 
>>> 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
>>
>> This message seems to indicate that problem is with device specification:
>> /dev/block/platform/mtk-msdc.0/by-name/userdata
>>
>> Can you check, that such device node exists before calling this activation?
>>
>> You can try to use "major:minor" pair instead (of the device above),
>> but it can sause problem if it is dynamic (it shouldn't be in this
>> environment though).
> 

I just tried passing the major:minor of the device, instead of a device
path, but I am still getting the same error, "Device lookup failed".

Any further hints on what could be the issue would be very much
appreciated...

Thanks and best regards,

Roman


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