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From:   David Howells <dhowells@redhat.com>
In-Reply-To: <3609b064-175c-fc18-cd1a-e177d0349c58@samba.org>
References: <3609b064-175c-fc18-cd1a-e177d0349c58@samba.org> <166855224228.1998592.2212551359609792175.stgit@warthog.procyon.org.uk>
To:     Stefan Metzmacher <metze@samba.org>
Cc:     dhowells@redhat.com, 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
Subject: Re: [PATCH] cifs: Fix problem with encrypted RDMA data read
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Content-ID: <2147869.1668582019.1@warthog.procyon.org.uk>
Date:   Wed, 16 Nov 2022 07:00:19 +0000
Message-ID: <2147870.1668582019@warthog.procyon.org.uk>
Precedence: bulk

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

David

[*] I don't know the correct RDMA terminology for these things.