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From: Milan Broz <gmazyland@gmail.com>
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Date: Sun, 26 Jul 2020 20:41:43 +0200
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Subject: Re: [dm-crypt] Attaching loopback device failed
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To: Fourhundred Thecat <400thecat@gmx.ch>, dm-crypt@saout.de

On 26/07/2020 20:23, Fourhundred Thecat wrote:
> Hello,
> 
> I have both luks headerand key in files
> 
> # ls
> LUKS-HEADER  key
> 
> the directory is read-only (chattr -R +i .)
> 
> When I try to luksOpen my paretition, I get following error:
> 
>   # cryptsetup --allow-discards luksOpen /dev/sda2 sda2 --header
> LUKS-HEADER --key-file key
>   Attaching loopback device failed (loop device with autoclear flag is
> required).
>   Device LUKS-HEADER doesn't exist or access denied.
> 
> when I change the current directory to read-write (chattr -R -i .) then
> it works.
> 
> But why does cryptsetup need luks header and key to be writable ?

It should not. Can you run the command with --debug and post the output?

Does it work if you activate it with read-only flag (--readonly / -r)?

Fopr these reports, we always need version (kernel, utility, crypto backend etc),
debug output should include all these versions.

Milan