linux-kernel - Re: [PATCH v2] nvmet-auth: update sc

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Message-ID: <31a4e5f0-43e1-4aed-af84-715aca53fa1b@suse.de>
Date: Wed, 5 Nov 2025 08:29:52 +0100
From: Hannes Reinecke <hare@...e.de>
To: alistair23@...il.com, kbusch@...nel.org, axboe@...nel.dk, hch@....de,
 sagi@...mberg.me, kch@...dia.com, linux-nvme@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v2] nvmet-auth: update sc_c in target host hash
 calculation

On 11/5/25 00:14, alistair23@...il.com wrote:
> From: Alistair Francis <alistair.francis@....com>
> 
> Commit 7e091add9c43 "nvme-auth: update sc_c in host response" added
> the sc_c variable to the dhchap queue context structure which is
> appropriately set during negotiate and then used in the host response.
> 
> This breaks secure concat connections with a Linux target as the target
> code wasn't updated at the same time. This patch fixes this by adding a
> new sc_c variable to the host hash calculations.
> 
> Fixes: 7e091add9c43 ("nvme-auth: update sc_c in host response")
> Signed-off-by: Alistair Francis <alistair.francis@....com>
> ---
> v2:
>   - Rebase on v6.18-rc4
>   - Add Fixes tag
> 
>   drivers/nvme/host/auth.c               | 1 +
>   drivers/nvme/target/auth.c             | 5 +++--
>   drivers/nvme/target/fabrics-cmd-auth.c | 1 +
>   drivers/nvme/target/nvmet.h            | 1 +
>   4 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/auth.c b/drivers/nvme/host/auth.c
> index a01178caf15b..19980122d3d5 100644
> --- a/drivers/nvme/host/auth.c
> +++ b/drivers/nvme/host/auth.c
> @@ -492,6 +492,7 @@ static int nvme_auth_dhchap_setup_host_response(struct nvme_ctrl *ctrl,
>   	ret = crypto_shash_update(shash, buf, 2);
>   	if (ret)
>   		goto out;
> +	memset(buf, 0, sizeof(buf));
>   	*buf = chap->sc_c;
>   	ret = crypto_shash_update(shash, buf, 1);
>   	if (ret)
> diff --git a/drivers/nvme/target/auth.c b/drivers/nvme/target/auth.c
> index 02c23998e13c..f54a1425262d 100644
> --- a/drivers/nvme/target/auth.c
> +++ b/drivers/nvme/target/auth.c
> @@ -298,7 +298,7 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
>   	const char *hash_name;
>   	u8 *challenge = req->sq->dhchap_c1;
>   	struct nvme_dhchap_key *transformed_key;
> -	u8 buf[4], sc_c = ctrl->concat ? 1 : 0;
> +	u8 buf[4];
>   	int ret;
>   
>   	hash_name = nvme_auth_hmac_name(ctrl->shash_id);
> @@ -367,7 +367,7 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
>   	ret = crypto_shash_update(shash, buf, 2);
>   	if (ret)
>   		goto out;
> -	*buf = sc_c;
> +	*buf = req->sq->sc_c;
>   	ret = crypto_shash_update(shash, buf, 1);
>   	if (ret)
>   		goto out;
> @@ -378,6 +378,7 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
>   	ret = crypto_shash_update(shash, ctrl->hostnqn, strlen(ctrl->hostnqn));
>   	if (ret)
>   		goto out;
> +	memset(buf, 0, sizeof(buf));
>   	ret = crypto_shash_update(shash, buf, 1);
>   	if (ret)
>   		goto out;
> diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
> index 5d7d913927d8..16894302ebe1 100644
> --- a/drivers/nvme/target/fabrics-cmd-auth.c
> +++ b/drivers/nvme/target/fabrics-cmd-auth.c
> @@ -43,6 +43,7 @@ static u8 nvmet_auth_negotiate(struct nvmet_req *req, void *d)
>   		 data->auth_protocol[0].dhchap.halen,
>   		 data->auth_protocol[0].dhchap.dhlen);
>   	req->sq->dhchap_tid = le16_to_cpu(data->t_id);
> +	req->sq->sc_c = le16_to_cpu(data->sc_c);
>   	if (data->sc_c != NVME_AUTH_SECP_NOSC) {
>   		if (!IS_ENABLED(CONFIG_NVME_TARGET_TCP_TLS))
>   			return NVME_AUTH_DHCHAP_FAILURE_CONCAT_MISMATCH;

Hmm. Storing 'sc_c' directly does away with the need for the 'concat'
controller setting.
Can't we just drop that and use 'sq->sc_c' directly when checking if
secure concatenation is enabled?

> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index 73da823a91fb..20be2fe43307 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -159,6 +159,7 @@ struct nvmet_sq {
>   	bool			authenticated;
>   	struct delayed_work	auth_expired_work;
>   	u16			dhchap_tid;
> +	u8			sc_c;
>   	u8			dhchap_status;
>   	u8			dhchap_step;
>   	u8			*dhchap_c1;
Cheers,Hannes

-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@...e.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich