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Message-ID: <88b441af-d6ae-4d46-aae5-0b649e76031d@samba.org>
Date:   Wed, 16 Nov 2022 10:05:11 +0100
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Subject: Re: [PATCH] cifs: Fix problem with encrypted RDMA data read
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To:     David Howells <dhowells@redhat.com>
Cc:     smfrench@gmail.com, tom@talpey.com, Long Li <longli@microsoft.com>,
        Namjae Jeon <linkinjeon@kernel.org>,
        linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <3609b064-175c-fc18-cd1a-e177d0349c58@samba.org>
 <166855224228.1998592.2212551359609792175.stgit@warthog.procyon.org.uk>
 <2147870.1668582019@warthog.procyon.org.uk>
From:   Stefan Metzmacher <metze@samba.org>
In-Reply-To: <2147870.1668582019@warthog.procyon.org.uk>
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Am 16.11.22 um 08:00 schrieb David Howells:
> Stefan Metzmacher <metze@samba.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