Re: crypto: xts: regression in 4.10

[Nicolas Porcel]

On Wed, Feb 22, 2017 at 12:31:30PM +0100, Milan Broz wrote:
> Kernel 4.10 works with LUKS and XTS in general (otherwise I would scream much 
> earlier:-)

I was surprised that it was still broken in the mainline release. All
the other regressions I had have been fixed. Also, I guess LUKS with
aes-xts is quite standard.

> I guess either there is a bug in some specific dependency missing
> dependency in kernel config. Could you send your kernel .config that fails?
> 
> Do you have ECB mode compiled-in as well?

Nice guess. I had ECB enabled as a module, and I don't think it was
present in the initramfs. Compiling it in the kernel solves the problem.
Thanks for the clue!

I now have the xts(ecb(aes-generic)) driver appearing in /proc/crypto.
I had no xts driver before.

I don't think it's necessary now to copy my kernel config. Also, it's
quite minimalist: make defconfig with a few drivers I need, mostly compiled
in the kernel.

> (See commit description, shouldn't XTS now select ECB as well? This seems to 
> me
> like a bug...)

I was actually confused by the message, I thought it would fallback to
the old implementation. I guess the XTS module should select ECB if
that's not the case. Should I submit a patch for that? Or maybe it would
be easier if a maintainer directly makes the change?

> What mail on dmcrypt list? I do not see any recent mail.

It was a mail from 2012, I should be more careful with search engines...

-- 
Nicolas Porcel

crypto: xts: regression in 4.10

[Nicolas Porcel]

Hello,

I am using aes-xts-plain64 with LUKS headers to crypt the root. In 4.10,
the partition cannot be opened and I have the following errors when
booting:

device-mapper: table: 253:0: crypt: Error allocating crypto tfm
device-mapper: ioctl: error adding target to table
device-mapper: reload ioctl on  failed: No such file or directory
Failed to setup dm-crypt key mapping for device /dev/mmcblk0p2
Check that the kernel supports aes-xts-plain64 cipher (check syslog for 
more info)

I found that this commit is responsible for the regression (reverting it
solves the problem):

> commit f1c131b45410a202eb45cc55980a7a9e4e4b4f40
> Author: Herbert Xu <herb...@gondor.apana.org.au>
> Date:   Tue Nov 22 20:08:19 2016 +0800
> 
> crypto: xts - Convert to skcipher

Some precision: I am using the vanilla kernel source for 4.10. The aes,
xts and dm-crypt modules are directly compiled in the kernel and not as
modules. I also had the same problem with kernel 4.10-rc*.

Is it a known issue? I found 1 related email with no answer on the
dm-crypt mailing. If this is a regression, I can start digging, although
any guidance would be greatly appreciated.

Thank you in advance,

Best regards,

-- 
Nicolas Porcel