[PATCH v2] nvmet-auth: update sc_c in target host hash calculation

[Alistair Francis]

On Wed, Nov 5, 2025 at 5:29 PM Hannes Reinecke <hare at suse.de> wrote:
>
> On 11/5/25 00:14, alistair23 at gmail.com wrote:
> > From: Alistair Francis <alistair.francis at wdc.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 at wdc.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?

I think we could drop ctrl->concat, but I feel like maybe that should
be a merge window change instead of late in the RC window.

Alistair

>
> > 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 at suse.de                                +49 911 74053 688
> SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
> HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich