Re: [PATCH rdma-next 00/13] Add RDMA inline crypto support

[Israel Rukshin]

Hi Sagi,

On 1/23/2023 1:27 PM, Sagi Grimberg wrote:
> >  From Israel,
> >
> > The purpose of this patchset is to add support for inline
> > encryption/decryption of the data at storage protocols like nvmf over
> > RDMA (at a similar way like integrity is used via unique mkey).
> >
> > This patchset adds support for plaintext keys. The patches were tested
> > on BF-3 HW with fscrypt tool to test this feature, which showed reduce
> > in CPU utilization when comparing at 64k or more IO size. The CPU 
> > utilization
> > was improved by more than 50% comparing to the SW only solution at 
> > this case.
> >
> > How to configure fscrypt to enable plaintext keys:
> >   # mkfs.ext4 -O encrypt /dev/nvme0n1
> >   # mount /dev/nvme0n1 /mnt/crypto -o inlinecrypt
> >   # head -c 64 /dev/urandom > /tmp/master_key
> >   # fscryptctl add_key /mnt/crypto/ < /tmp/master_key
> >   # mkdir /mnt/crypto/test1
> >   # fscryptctl set_policy 152c41b2ea39fa3d90ea06448456e7fb 
> > /mnt/crypto/test1
> >     ** “152c41b2ea39fa3d90ea06448456e7fb” is the output of the
> >        “fscryptctl add_key” command.
> >   # echo foo > /mnt/crypto/test1/foo
> >
> > Notes:
> >   - At plaintext mode only, the user set a master key and the fscrypt
> >     driver derived from it the DEK and the key identifier.
> >   - 152c41b2ea39fa3d90ea06448456e7fb is the derived key identifier
> >   - Only on the first IO, nvme-rdma gets a callback to load the 
> > derived DEK.
> >
> > There is no special configuration to support crypto at nvme modules.
>
> Hey, this looks sane to me in a very first glance.
>
> Few high level questions:
> - what happens with multipathing? when if not all devices are
> capable. SW fallback?
SW fallback happens every time the device doesn't support the specific 
crypto request (which include data-unit-size, mode and dun_bytes).
So with multipathing, one path uses the HW crypto offload and the other 
one uses the SW fallback.
> - Does the crypt stuff stay intact when bio is requeued?
Yes, the crypto ctx is copied when cloning the bio.
> I'm assuming you tested this with multipathing? This is not very
> useful if it is incompatible with it.
Yes, sure.
You can see the call to  blk_crypto_reprogram_all_keys(), which is 
called when the controller was reconnected after port toggling.

- Israel