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Date:   Wed, 25 Oct 2023 08:32:22 +0200
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Subject: Re: [PATCH v2 3/3] nvme-auth: always set valid seq_num in dhchap
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To:     Mark O'Donovan <shiftee@posteo.net>, linux-kernel@vger.kernel.org
Cc:     linux-nvme@lists.infradead.org, sagi@grimberg.me, hch@lst.de,
        axboe@kernel.dk, kbusch@kernel.org
References: <20231023140003.58019-1-shiftee@posteo.net>
 <20231023140003.58019-4-shiftee@posteo.net>
From:   Hannes Reinecke <hare@suse.de>
In-Reply-To: <20231023140003.58019-4-shiftee@posteo.net>
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On 10/23/23 16:00, Mark O'Donovan wrote:
> Currently a seqnum of zero is sent during uni-directional
> authentication. The zero value is reserved for the secure channel
> feature which is not yet implemented.
> 
> Relevant extract from the spec:
> The value 0h is used to indicate that bidirectional authentication
> is not performed, but a challenge value C2 is carried in order to
> generate a pre-shared key (PSK) for subsequent establishment of a
> secure channel
> 
> Signed-off-by: Mark O'Donovan <shiftee@posteo.net>
> 
> ---
> v1: used incorrect prefix nvme-tcp
> v2: added spec extract to commit message
> 
>   drivers/nvme/host/auth.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/auth.c b/drivers/nvme/host/auth.c
> index 8558a02865ac..7f6b2e99a78c 100644
> --- a/drivers/nvme/host/auth.c
> +++ b/drivers/nvme/host/auth.c
> @@ -316,15 +316,14 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,
>   		chap->bi_directional = true;
>   		get_random_bytes(chap->c2, chap->hash_len);
>   		data->cvalid = 1;
> -		chap->s2 = nvme_auth_get_seqnum();
>   		memcpy(data->rval + chap->hash_len, chap->c2,
>   		       chap->hash_len);
>   		dev_dbg(ctrl->device, "%s: qid %d ctrl challenge %*ph\n",
>   			__func__, chap->qid, (int)chap->hash_len, chap->c2);
>   	} else {
>   		memset(chap->c2, 0, chap->hash_len);
> -		chap->s2 = 0;
>   	}
> +	chap->s2 = nvme_auth_get_seqnum();
>   	data->seqnum = cpu_to_le32(chap->s2);
>   	if (chap->host_key_len) {
>   		dev_dbg(ctrl->device, "%s: qid %d host public key %*ph\n",

I guess you'll need to fix up nvmet, too, as this currently ignores 's2' 
when 'cvalid' is false.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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