[dm-crypt] Attaching loopback device failed

[dm-crypt] Attaching loopback device failed

[Fourhundred Thecat]

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 ?

thanks,

Re: [dm-crypt] Attaching loopback device failed

[Milan Broz]

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