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Message-ID: <CAKmqyKNSV1GdipOrOs3csyoTMKX1+mxTgxnOq9xnb3vmRN0RgA@mail.gmail.com>
Date: Wed, 22 Oct 2025 14:40:55 +1000
From: Alistair Francis <alistair23@...il.com>
To: Hannes Reinecke <hare@...e.de>
Cc: chuck.lever@...cle.com, hare@...nel.org,
kernel-tls-handshake@...ts.linux.dev, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
linux-nvme@...ts.infradead.org, linux-nfs@...r.kernel.org, kbusch@...nel.org,
axboe@...nel.dk, hch@....de, sagi@...mberg.me, kch@...dia.com,
Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v4 4/7] net/handshake: Support KeyUpdate message types
On Tue, Oct 21, 2025 at 1:19 PM Alistair Francis <alistair23@...il.com> wrote:
>
> On Mon, Oct 20, 2025 at 4:09 PM Hannes Reinecke <hare@...e.de> wrote:
> >
> > On 10/17/25 06:23, alistair23@...il.com wrote:
> > > From: Alistair Francis <alistair.francis@....com>
> > >
> > > When reporting the msg-type to userspace let's also support reporting
> > > KeyUpdate events. This supports reporting a client/server event and if
> > > the other side requested a KeyUpdateRequest.
> > >
> > > Link: https://datatracker.ietf.org/doc/html/rfc8446#section-4.6.3
> > > Signed-off-by: Alistair Francis <alistair.francis@....com>
> > > ---
> > > v4:
> > > - Don't overload existing functions, instead create new ones
> > > v3:
> > > - Fixup yamllint and kernel-doc failures
> > >
> > > Documentation/netlink/specs/handshake.yaml | 16 ++++-
> > > drivers/nvme/host/tcp.c | 15 +++-
> > > drivers/nvme/target/tcp.c | 10 ++-
> > > include/net/handshake.h | 8 +++
> > > include/uapi/linux/handshake.h | 13 ++++
> > > net/handshake/tlshd.c | 83 +++++++++++++++++++++-
> > > 6 files changed, 137 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/Documentation/netlink/specs/handshake.yaml b/Documentation/netlink/specs/handshake.yaml
> > > index a273bc74d26f..c72ec8fa7d7a 100644
> > > --- a/Documentation/netlink/specs/handshake.yaml
> > > +++ b/Documentation/netlink/specs/handshake.yaml
> > > @@ -21,12 +21,18 @@ definitions:
> > > type: enum
> > > name: msg-type
> > > value-start: 0
> > > - entries: [unspec, clienthello, serverhello]
> > > + entries: [unspec, clienthello, serverhello, clientkeyupdate,
> > > + clientkeyupdaterequest, serverkeyupdate, serverkeyupdaterequest]
> > > -
> >
> > Why do we need the 'keyupdate' and 'keyupdaterequest' types?
>
> msg-type indicates if it's a client or server and hello or keyupdate,
> the idea being
>
> client:
> - Hello
> - KeyUpdate
>
> server:
> - Hello
> - KeyUpdate
>
> I'll drop clientkeyupdaterequest and serverkeyupdaterequest
>
> > Isn't the 'keyupdate' type enough, and can we specify anything
> > else via the update type?
>
> Once we know if it's a client or server KeyUpdate we need to know if
> we are receiving one, sending one or receiving one with the
> request_update flag set, hence key-update-type
>
> >
> > > type: enum
> > > name: auth
> > > value-start: 0
> > > entries: [unspec, unauth, psk, x509]
> > > + -
> > > + type: enum
> > > + name: key-update-type
> > > + value-start: 0
> > > + entries: [unspec, send, received, received_request_update]
> >
> > See above.
> >
> > >
> > > attribute-sets:
> > > -
> > > @@ -74,6 +80,13 @@ attribute-sets:
> > > -
> > > name: keyring
> > > type: u32
> > > + -
> > > + name: key-update-request
> > > + type: u32
> > > + enum: key-update-type
> > > + -
> > > + name: key-serial
> > > + type: u32
> >
> > Not sure if I like key-serial. Yes, it is a key serial number,
> > but it's not the serial number of the updated key (rather the serial
> > number of the key holding the session information).
> > Maybe 'key-update-serial' ?
> >
> > > -
> > > name: done
> > > attributes:
> > > @@ -116,6 +129,7 @@ operations:
> > > - certificate
> > > - peername
> > > - keyring
> > > + - key-serial
> > > -
> > > name: done
> > > doc: Handler reports handshake completion
> > > diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> > > index 611be56f8013..2696bf97dfac 100644
> > > --- a/drivers/nvme/host/tcp.c
> > > +++ b/drivers/nvme/host/tcp.c
> > > @@ -20,6 +20,7 @@
> > > #include <linux/iov_iter.h>
> > > #include <net/busy_poll.h>
> > > #include <trace/events/sock.h>
> > > +#include <uapi/linux/handshake.h>
> > >
> > > #include "nvme.h"
> > > #include "fabrics.h"
> > > @@ -206,6 +207,10 @@ static struct workqueue_struct *nvme_tcp_wq;
> > > static const struct blk_mq_ops nvme_tcp_mq_ops;
> > > static const struct blk_mq_ops nvme_tcp_admin_mq_ops;
> > > static int nvme_tcp_try_send(struct nvme_tcp_queue *queue);
> > > +static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
> > > + struct nvme_tcp_queue *queue,
> > > + key_serial_t pskid,
> > > + handshake_key_update_type keyupdate);
> > >
> > > static inline struct nvme_tcp_ctrl *to_tcp_ctrl(struct nvme_ctrl *ctrl)
> > > {
> > > @@ -1726,7 +1731,8 @@ static void nvme_tcp_tls_done(void *data, int status, key_serial_t pskid,
> > >
> > > static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
> > > struct nvme_tcp_queue *queue,
> > > - key_serial_t pskid)
> > > + key_serial_t pskid,
> > > + handshake_key_update_type keyupdate)
> > > {
> > > int qid = nvme_tcp_queue_id(queue);
> > > int ret;
> > > @@ -1748,7 +1754,10 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
> > > args.ta_timeout_ms = tls_handshake_timeout * 1000;
> > > queue->tls_err = -EOPNOTSUPP;
> > > init_completion(&queue->tls_complete);
> > > - ret = tls_client_hello_psk(&args, GFP_KERNEL);
> > > + if (keyupdate == HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC)
> > > + ret = tls_client_hello_psk(&args, GFP_KERNEL);
> > > + else
> > > + ret = tls_client_keyupdate_psk(&args, GFP_KERNEL, keyupdate);
> > > if (ret) {
> > > dev_err(nctrl->device, "queue %d: failed to start TLS: %d\n",
> > > qid, ret);
> > > @@ -1898,7 +1907,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid,
> > >
> > > /* If PSKs are configured try to start TLS */
> > > if (nvme_tcp_tls_configured(nctrl) && pskid) {
> > > - ret = nvme_tcp_start_tls(nctrl, queue, pskid);
> > > + ret = nvme_tcp_start_tls(nctrl, queue, pskid, HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC);
> > > if (ret)
> > > goto err_init_connect;
> > > }
> > > diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> > > index 4ef4dd140ada..8aeec4a7f136 100644
> > > --- a/drivers/nvme/target/tcp.c
> > > +++ b/drivers/nvme/target/tcp.c
> > > @@ -1833,7 +1833,8 @@ static void nvmet_tcp_tls_handshake_timeout(struct work_struct *w)
> > > kref_put(&queue->kref, nvmet_tcp_release_queue);
> > > }
> > >
> > > -static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
> > > +static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue,
> > > + handshake_key_update_type keyupdate)
> > > {
> > > int ret = -EOPNOTSUPP;
> > > struct tls_handshake_args args;
> > > @@ -1852,7 +1853,10 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
> > > args.ta_keyring = key_serial(queue->port->nport->keyring);
> > > args.ta_timeout_ms = tls_handshake_timeout * 1000;
> > >
> > > - ret = tls_server_hello_psk(&args, GFP_KERNEL);
> > > + if (keyupdate == HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC)
> > > + ret = tls_server_hello_psk(&args, GFP_KERNEL);
> > > + else
> > > + ret = tls_server_keyupdate_psk(&args, GFP_KERNEL, keyupdate);
> > > if (ret) {
> > > kref_put(&queue->kref, nvmet_tcp_release_queue);
> > > pr_err("failed to start TLS, err=%d\n", ret);
> > > @@ -1934,7 +1938,7 @@ static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
> > > sk->sk_data_ready = port->data_ready;
> > > write_unlock_bh(&sk->sk_callback_lock);
> > > if (!nvmet_tcp_try_peek_pdu(queue)) {
> > > - if (!nvmet_tcp_tls_handshake(queue))
> > > + if (!nvmet_tcp_tls_handshake(queue, HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC))
> > > return;
> > > /* TLS handshake failed, terminate the connection */
> > > goto out_destroy_sq;
> > > diff --git a/include/net/handshake.h b/include/net/handshake.h
> > > index dc2222fd6d99..084c92a20b68 100644
> > > --- a/include/net/handshake.h
> > > +++ b/include/net/handshake.h
> > > @@ -10,6 +10,10 @@
> > > #ifndef _NET_HANDSHAKE_H
> > > #define _NET_HANDSHAKE_H
> > >
> > > +#include <uapi/linux/handshake.h>
> > > +
> > > +#define handshake_key_update_type u32
> > > +
> > Huh?
> > You define it as 'u32' here
> >
> > > enum {
> > > TLS_NO_KEYRING = 0,
> > > TLS_NO_PEERID = 0,
> > > @@ -38,8 +42,12 @@ struct tls_handshake_args {
> > > int tls_client_hello_anon(const struct tls_handshake_args *args, gfp_t flags);
> > > int tls_client_hello_x509(const struct tls_handshake_args *args, gfp_t flags);
> > > int tls_client_hello_psk(const struct tls_handshake_args *args, gfp_t flags);
> > > +int tls_client_keyupdate_psk(const struct tls_handshake_args *args, gfp_t flags,
> > > + handshake_key_update_type keyupdate);
> > > int tls_server_hello_x509(const struct tls_handshake_args *args, gfp_t flags);
> > > int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags);
> > > +int tls_server_keyupdate_psk(const struct tls_handshake_args *args, gfp_t flags,
> > > + handshake_key_update_type keyupdate);
> > >
> > > bool tls_handshake_cancel(struct sock *sk);
> > > void tls_handshake_close(struct socket *sock);
> > > diff --git a/include/uapi/linux/handshake.h b/include/uapi/linux/handshake.h
> > > index b68ffbaa5f31..b691530073c6 100644
> > > --- a/include/uapi/linux/handshake.h
> > > +++ b/include/uapi/linux/handshake.h
> > > @@ -19,6 +19,10 @@ enum handshake_msg_type {
> > > HANDSHAKE_MSG_TYPE_UNSPEC,
> > > HANDSHAKE_MSG_TYPE_CLIENTHELLO,
> > > HANDSHAKE_MSG_TYPE_SERVERHELLO,
> > > + HANDSHAKE_MSG_TYPE_CLIENTKEYUPDATE,
> > > + HANDSHAKE_MSG_TYPE_CLIENTKEYUPDATEREQUEST,
> > > + HANDSHAKE_MSG_TYPE_SERVERKEYUPDATE,
> > > + HANDSHAKE_MSG_TYPE_SERVERKEYUPDATEREQUEST,
> > > };
> > >
> > > enum handshake_auth {
> > > @@ -28,6 +32,13 @@ enum handshake_auth {
> > > HANDSHAKE_AUTH_X509,
> > > };
> > >
> > > +enum handshake_key_update_type {
> > > + HANDSHAKE_KEY_UPDATE_TYPE_UNSPEC,
> > > + HANDSHAKE_KEY_UPDATE_TYPE_SEND,
> > > + HANDSHAKE_KEY_UPDATE_TYPE_RECEIVED,
> > > + HANDSHAKE_KEY_UPDATE_TYPE_RECEIVED_REQUEST_UPDATE,
> > > +};
> > > +
> >
> > and here it's an enum. Please kill the first declaration.
> >
> > > enum {
> > > HANDSHAKE_A_X509_CERT = 1,
> > > HANDSHAKE_A_X509_PRIVKEY,
> > > @@ -46,6 +57,8 @@ enum {
> > > HANDSHAKE_A_ACCEPT_CERTIFICATE,
> > > HANDSHAKE_A_ACCEPT_PEERNAME,
> > > HANDSHAKE_A_ACCEPT_KEYRING,
> > > + HANDSHAKE_A_ACCEPT_KEY_UPDATE_REQUEST,
> > > + HANDSHAKE_A_ACCEPT_KEY_SERIAL,
> > >
> > > __HANDSHAKE_A_ACCEPT_MAX,
> > > HANDSHAKE_A_ACCEPT_MAX = (__HANDSHAKE_A_ACCEPT_MAX - 1)
> > > diff --git a/net/handshake/tlshd.c b/net/handshake/tlshd.c
> > > index 2549c5dbccd8..c40839977ab9 100644
> > > --- a/net/handshake/tlshd.c
> > > +++ b/net/handshake/tlshd.c
> > > @@ -41,6 +41,7 @@ struct tls_handshake_req {
> > > unsigned int th_num_peerids;
> > > key_serial_t th_peerid[5];
> > >
> > > + int th_key_update_request;
> > > key_serial_t user_session_id;
> > > };
> > >
> > Why 'int' ? Can it be negative?
> > If not please make it an 'unsigned int'
> >
> > > @@ -58,7 +59,8 @@ tls_handshake_req_init(struct handshake_req *req,
> > > treq->th_num_peerids = 0;
> > > treq->th_certificate = TLS_NO_CERT;
> > > treq->th_privkey = TLS_NO_PRIVKEY;
> > > - treq->user_session_id = TLS_NO_PRIVKEY;
> > > + treq->user_session_id = args->user_session_id;
> > > +
> > > return treq;
> > > }
> > >
> > > @@ -265,6 +267,16 @@ static int tls_handshake_accept(struct handshake_req *req,
> > > break;
> > > }
> > >
> > > + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_KEY_SERIAL,
> > > + treq->user_session_id);
> > > + if (ret < 0)
> > > + goto out_cancel;
> > > +
> > > + ret = nla_put_u32(msg, HANDSHAKE_A_ACCEPT_KEY_UPDATE_REQUEST,
> > > + treq->th_key_update_request);
> > > + if (ret < 0)
> > > + goto out_cancel;
> > > +
> > > genlmsg_end(msg, hdr);
> > > return genlmsg_reply(msg, info);
> > >
> > > @@ -372,6 +384,44 @@ int tls_client_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
> > > }
> > > EXPORT_SYMBOL(tls_client_hello_psk);
> > >
> > > +/**
> > > + * tls_client_keyupdate_psk - request a PSK-based TLS handshake on a socket
> > > + * @args: socket and handshake parameters for this request
> > > + * @flags: memory allocation control flags
> > > + * @keyupdate: specifies the type of KeyUpdate operation
> > > + *
> > > + * Return values:
> > > + * %0: Handshake request enqueue; ->done will be called when complete
> > > + * %-EINVAL: Wrong number of local peer IDs
> > > + * %-ESRCH: No user agent is available
> > > + * %-ENOMEM: Memory allocation failed
> > > + */
> > > +int tls_client_keyupdate_psk(const struct tls_handshake_args *args, gfp_t flags,
> > > + handshake_key_update_type keyupdate)
> > > +{
> > > + struct tls_handshake_req *treq;
> > > + struct handshake_req *req;
> > > + unsigned int i;
> > > +
> > > + if (!args->ta_num_peerids ||
> > > + args->ta_num_peerids > ARRAY_SIZE(treq->th_peerid))
> > > + return -EINVAL;
> > > +
> > > + req = handshake_req_alloc(&tls_handshake_proto, flags);
> > > + if (!req)
> > > + return -ENOMEM;
> > > + treq = tls_handshake_req_init(req, args);
> > > + treq->th_type = HANDSHAKE_MSG_TYPE_CLIENTKEYUPDATE;
> > > + treq->th_key_update_request = keyupdate;
> > > + treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
> > > + treq->th_num_peerids = args->ta_num_peerids;
> > > + for (i = 0; i < args->ta_num_peerids; i++)
> > > + treq->th_peerid[i] = args->ta_my_peerids[i];
> > Hmm?
> > Do we use the 'peerids'?
>
> We don't, this is just copied from the
> tls_client_hello_psk()/tls_server_hello_psk() to provide the same
> information to keep things more consistent.
>
> I can remove setting these
Actually, ktls-utils (tlshd) expects these to be set, so I think we
should leave them as is
Alistair
>
> > I thought that the information was encoded in the session, ie
> > the 'user_session_id' ?
> >
> > > +
> > > + return handshake_req_submit(args->ta_sock, req, flags);
> > > +}
> > > +EXPORT_SYMBOL(tls_client_keyupdate_psk);
> > > +
> > > /**
> > > * tls_server_hello_x509 - request a server TLS handshake on a socket
> > > * @args: socket and handshake parameters for this request
> > > @@ -428,6 +478,37 @@ int tls_server_hello_psk(const struct tls_handshake_args *args, gfp_t flags)
> > > }
> > > EXPORT_SYMBOL(tls_server_hello_psk);
> > >
> > > +/**
> > > + * tls_server_keyupdate_psk - request a server TLS KeyUpdate on a socket
> > > + * @args: socket and handshake parameters for this request
> > > + * @flags: memory allocation control flags
> > > + * @keyupdate: specifies the type of KeyUpdate operation
> > > + *
> > > + * Return values:
> > > + * %0: Handshake request enqueue; ->done will be called when complete
> > > + * %-ESRCH: No user agent is available
> > > + * %-ENOMEM: Memory allocation failed
> > > + */
> > > +int tls_server_keyupdate_psk(const struct tls_handshake_args *args, gfp_t flags,
> > > + handshake_key_update_type keyupdate)
> > > +{
> > > + struct tls_handshake_req *treq;
> > > + struct handshake_req *req;
> > > +
> > > + req = handshake_req_alloc(&tls_handshake_proto, flags);
> > > + if (!req)
> > > + return -ENOMEM;
> > > + treq = tls_handshake_req_init(req, args);
> > > + treq->th_type = HANDSHAKE_MSG_TYPE_SERVERKEYUPDATE;
> > > + treq->th_key_update_request = keyupdate;
> > > + treq->th_auth_mode = HANDSHAKE_AUTH_PSK;
> > > + treq->th_num_peerids = 1;
> > > + treq->th_peerid[0] = args->ta_my_peerids[0];
> >
> > Same here. Why do we need to set 'peerid'?
> >
> > > +
> > > + return handshake_req_submit(args->ta_sock, req, flags);
> > > +}
> > > +EXPORT_SYMBOL(tls_server_keyupdate_psk);
> > > +
> > > /**
> > > * tls_handshake_cancel - cancel a pending handshake
> > > * @sk: socket on which there is an ongoing handshake
> > Nit: we _could_ overload 'peerid' with the user_session_id,then we
> > wouldn't need to specify a new field in the handshake
> > request.
> > But that's arguably quite hackish.
>
> Oh no! Let's not do that. That just seems prone to confusion
>
> Alistair
>
> >
> > 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
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