linux-kernel - Re: [PATCH] cifs: Fix problem with encrypted RDMA data read

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Message-ID: <88b441af-d6ae-4d46-aae5-0b649e76031d@samba.org>
Date:   Wed, 16 Nov 2022 10:05:11 +0100
From:   Stefan Metzmacher <metze@...ba.org>
To:     David Howells <dhowells@...hat.com>
Cc:     smfrench@...il.com, tom@...pey.com, Long Li <longli@...rosoft.com>,
        Namjae Jeon <linkinjeon@...nel.org>,
        linux-cifs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cifs: Fix problem with encrypted RDMA data read

Am 16.11.22 um 08:00 schrieb David Howells:
> Stefan Metzmacher <metze@...ba.org> wrote:
> 
>> I'm not sure I understand why this would fix anything when encryption is
>> enabled.
>>
>> Is the payload still be offloaded as plaintext? Otherwise we wouldn't have
>> use_rdma_mr...  So this rather looks like a fix for the non encrypted case.
> 
> The "inline"[*] PDUs are encrypted, but the direct RDMA data transmission is
> not.  I'm not sure if this is a bug in ksmbd.

It's a bug in the client!

> As I understand it, encrypting and decrypting the directly transferred
> data would need to be done by the NIC, not the cifs driver.

No, the encryption needs to happen above the RDMA/NIC layer.

metze