Message-ID: <87d71462-cadd-f572-c007-1909430fe4ab@grimberg.me>
Date: Sun, 20 Aug 2023 17:55:34 +0300
From: Sagi Grimberg <sagi@...mberg.me>
To: Hannes Reinecke <hare@...e.de>, Christoph Hellwig <hch@....de>
Cc: Keith Busch <kbusch@...nel.org>, linux-nvme@...ts.infradead.org,
 Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH 16/18] nvmet-tcp: enable TLS handshake upcall



On 8/16/23 15:06, Hannes Reinecke wrote:
> TLS handshake is handled in userspace with the
> netlink tls handshake protocol.
> The patch adds a function to start the TLS handshake
> upcall for any incoming network connections if
> the TCP TSAS sectype is set to 'tls1.3'.
> A config option NVME_TARGET_TCP_TLS selects whether
> the TLS handshake upcall should be compiled in.
> The patch also adds reference counting to
> struct nvmet_tcp_queue to ensure the queue is
> always valid when the the TLS handshake completes.
> 
> Signed-off-by: Hannes Reinecke <hare@...e.de>
> ---
>   drivers/nvme/target/Kconfig    |  15 ++++
>   drivers/nvme/target/configfs.c |  21 +++++
>   drivers/nvme/target/nvmet.h    |   1 +
>   drivers/nvme/target/tcp.c      | 145 ++++++++++++++++++++++++++++++++-
>   4 files changed, 178 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvme/target/Kconfig b/drivers/nvme/target/Kconfig
> index 79fc64035ee3..c56cb1005327 100644
> --- a/drivers/nvme/target/Kconfig
> +++ b/drivers/nvme/target/Kconfig
> @@ -84,6 +84,21 @@ config NVME_TARGET_TCP
>   
>   	  If unsure, say N.
>   
> +config NVME_TARGET_TCP_TLS
> +	bool "NVMe over Fabrics TCP target TLS encryption support"
> +	depends on NVME_TARGET_TCP
> +	select NVME_COMMON
> +	select NVME_KEYRING
> +	select NET_HANDSHAKE
> +	select KEYS
> +	help
> +	  Enables TLS encryption for the NVMe TCP target using the netlink handshake API.
> +
> +	  The TLS handshake daemon is available at
> +	  https://github.com/oracle/ktls-utils.
> +
> +	  If unsure, say N.
> +
>   config NVME_TARGET_AUTH
>   	bool "NVMe over Fabrics In-band Authentication support"
>   	depends on NVME_TARGET
> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
> index 483569c3f622..b780ce049163 100644
> --- a/drivers/nvme/target/configfs.c
> +++ b/drivers/nvme/target/configfs.c
> @@ -15,6 +15,7 @@
>   #ifdef CONFIG_NVME_TARGET_AUTH
>   #include <linux/nvme-auth.h>
>   #endif
> +#include <linux/nvme-keyring.h>
>   #include <crypto/hash.h>
>   #include <crypto/kpp.h>
>   
> @@ -396,6 +397,17 @@ static ssize_t nvmet_addr_tsas_store(struct config_item *item,
>   	return -EINVAL;
>   
>   found:
> +	if (sectype == NVMF_TCP_SECTYPE_TLS13) {
> +		if (!IS_ENABLED(CONFIG_NVME_TARGET_TCP_TLS)) {
> +			pr_err("TLS is not supported\n");
> +			return -EINVAL;
> +		}
> +		if (!port->keyring) {
> +			pr_err("TLS keyring not configured\n");
> +			return -EINVAL;
> +		}
> +	}
> +
>   	nvmet_port_init_tsas_tcp(port, sectype);
>   	/*
>   	 * The TLS implementation currently does not support
> @@ -1814,6 +1826,7 @@ static void nvmet_port_release(struct config_item *item)
>   	flush_workqueue(nvmet_wq);
>   	list_del(&port->global_entry);
>   
> +	key_put(port->keyring);
>   	kfree(port->ana_state);
>   	kfree(port);
>   }
> @@ -1863,6 +1876,14 @@ static struct config_group *nvmet_ports_make(struct config_group *group,
>   		return ERR_PTR(-ENOMEM);
>   	}
>   
> +	if (nvme_keyring_id()) {
> +		port->keyring = key_lookup(nvme_keyring_id());
> +		if (IS_ERR(port->keyring)) {
> +			pr_warn("NVMe keyring not available, disabling TLS\n");
> +			port->keyring = NULL;
> +		}
> +	}
> +
>   	for (i = 1; i <= NVMET_MAX_ANAGRPS; i++) {
>   		if (i == NVMET_DEFAULT_ANA_GRPID)
>   			port->ana_state[1] = NVME_ANA_OPTIMIZED;
> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
> index 87da62e4b743..e35a03260f45 100644
> --- a/drivers/nvme/target/nvmet.h
> +++ b/drivers/nvme/target/nvmet.h
> @@ -158,6 +158,7 @@ struct nvmet_port {
>   	struct config_group		ana_groups_group;
>   	struct nvmet_ana_group		ana_default_group;
>   	enum nvme_ana_state		*ana_state;
> +	struct key			*keyring;
>   	void				*priv;
>   	bool				enabled;
>   	int				inline_data_size;
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index f19ea9d923fd..3e447593ea72 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -8,9 +8,13 @@
>   #include <linux/init.h>
>   #include <linux/slab.h>
>   #include <linux/err.h>
> +#include <linux/key.h>
>   #include <linux/nvme-tcp.h>
> +#include <linux/nvme-keyring.h>
>   #include <net/sock.h>
>   #include <net/tcp.h>
> +#include <net/tls.h>
> +#include <net/handshake.h>
>   #include <linux/inet.h>
>   #include <linux/llist.h>
>   #include <crypto/hash.h>
> @@ -66,6 +70,16 @@ device_param_cb(idle_poll_period_usecs, &set_param_ops,
>   MODULE_PARM_DESC(idle_poll_period_usecs,
>   		"nvmet tcp io_work poll till idle time period in usecs: Default 0");
>   
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> +/*
> + * TLS handshake timeout
> + */
> +static int tls_handshake_timeout = 10;
> +module_param(tls_handshake_timeout, int, 0644);
> +MODULE_PARM_DESC(tls_handshake_timeout,
> +		 "nvme TLS handshake timeout in seconds (default 10)");
> +#endif
> +
>   #define NVMET_TCP_RECV_BUDGET		8
>   #define NVMET_TCP_SEND_BUDGET		8
>   #define NVMET_TCP_IO_WORK_BUDGET	64
> @@ -122,6 +136,7 @@ struct nvmet_tcp_cmd {
>   
>   enum nvmet_tcp_queue_state {
>   	NVMET_TCP_Q_CONNECTING,
> +	NVMET_TCP_Q_TLS_HANDSHAKE,
>   	NVMET_TCP_Q_LIVE,
>   	NVMET_TCP_Q_DISCONNECTING,
>   };
> @@ -132,6 +147,7 @@ struct nvmet_tcp_queue {
>   	struct work_struct	io_work;
>   	struct nvmet_cq		nvme_cq;
>   	struct nvmet_sq		nvme_sq;
> +	struct kref		kref;
>   
>   	/* send state */
>   	struct nvmet_tcp_cmd	*cmds;
> @@ -155,6 +171,10 @@ struct nvmet_tcp_queue {
>   	struct ahash_request	*snd_hash;
>   	struct ahash_request	*rcv_hash;
>   
> +	/* TLS state */
> +	key_serial_t		tls_pskid;
> +	struct delayed_work	tls_handshake_tmo_work;
> +
>   	unsigned long           poll_end;
>   
>   	spinlock_t		state_lock;
> @@ -1283,12 +1303,26 @@ static int nvmet_tcp_try_recv(struct nvmet_tcp_queue *queue,
>   	return ret;
>   }
>   
> +static void nvmet_tcp_release_queue(struct kref *kref)
> +{
> +	struct nvmet_tcp_queue *queue =
> +		container_of(kref, struct nvmet_tcp_queue, kref);
> +
> +	WARN_ON(queue->state != NVMET_TCP_Q_DISCONNECTING);
> +	queue_work(nvmet_wq, &queue->release_work);
> +}
> +
>   static void nvmet_tcp_schedule_release_queue(struct nvmet_tcp_queue *queue)
>   {
>   	spin_lock_bh(&queue->state_lock);
> +	if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
> +		/* Socket closed during handshake */
> +		tls_handshake_cancel(queue->sock->sk);

Can you call this under a spinlock?
I think you want the handshake cancel inside the release_work
no?

> +		queue->state = NVMET_TCP_Q_CONNECTING;

This state transition is weird.

> +	}
>   	if (queue->state != NVMET_TCP_Q_DISCONNECTING) {
>   		queue->state = NVMET_TCP_Q_DISCONNECTING;
> -		queue_work(nvmet_wq, &queue->release_work);
> +		kref_put(&queue->kref, nvmet_tcp_release_queue);

This change makes sense, but I think its the only one in this
function.

>   	}
>   	spin_unlock_bh(&queue->state_lock);
>   }
> @@ -1485,6 +1519,7 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
>   	mutex_unlock(&nvmet_tcp_queue_mutex);
>   
>   	nvmet_tcp_restore_socket_callbacks(queue);
> +	cancel_delayed_work_sync(&queue->tls_handshake_tmo_work);
>   	cancel_work_sync(&queue->io_work);
>   	/* stop accepting incoming data */
>   	queue->rcv_state = NVMET_TCP_RECV_ERR;
> @@ -1512,8 +1547,13 @@ static void nvmet_tcp_data_ready(struct sock *sk)
>   
>   	read_lock_bh(&sk->sk_callback_lock);
>   	queue = sk->sk_user_data;
> -	if (likely(queue))
> -		queue_work_on(queue_cpu(queue), nvmet_tcp_wq, &queue->io_work);
> +	if (likely(queue)) {
> +		if (queue->data_ready)
> +			queue->data_ready(sk);
> +		if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE)
> +			queue_work_on(queue_cpu(queue), nvmet_tcp_wq,
> +				      &queue->io_work);
> +	}
>   	read_unlock_bh(&sk->sk_callback_lock);
>   }
>   
> @@ -1621,6 +1661,79 @@ static int nvmet_tcp_set_queue_sock(struct nvmet_tcp_queue *queue)
>   	return ret;
>   }
>   
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> +static void nvmet_tcp_tls_handshake_done(void *data, int status,
> +					 key_serial_t peerid)
> +{
> +	struct nvmet_tcp_queue *queue = data;
> +
> +	pr_debug("queue %d: TLS handshake done, key %x, status %d\n",
> +		 queue->idx, peerid, status);
> +	spin_lock_bh(&queue->state_lock);
> +	WARN_ON(queue->state != NVMET_TCP_Q_TLS_HANDSHAKE);

If this happens, you probably need to return without doing anything
else...

> +	if (!status)
> +		queue->tls_pskid = peerid;
> +	queue->state = NVMET_TCP_Q_CONNECTING;
> +	spin_unlock_bh(&queue->state_lock);
> +
> +	cancel_delayed_work_sync(&queue->tls_handshake_tmo_work);
> +	if (status)
> +		nvmet_tcp_schedule_release_queue(queue);
> +	else
> +		nvmet_tcp_set_queue_sock(queue);
> +	kref_put(&queue->kref, nvmet_tcp_release_queue);
> +}
> +
> +static void nvmet_tcp_tls_handshake_timeout(struct work_struct *w)
> +{
> +	struct nvmet_tcp_queue *queue = container_of(to_delayed_work(w),
> +			struct nvmet_tcp_queue, tls_handshake_tmo_work);
> +
> +	pr_warn("queue %d: TLS handshake timeout\n", queue->idx);
> +	/*
> +	 * If tls_handshake_cancel() fails we've lost the race with
> +	 * nvmet_tcp_tls_handshake_done() */
> +	if (!tls_handshake_cancel(queue->sock->sk))
> +		return;
> +	spin_lock_bh(&queue->state_lock);
> +	WARN_ON(queue->state != NVMET_TCP_Q_TLS_HANDSHAKE);
> +	queue->state = NVMET_TCP_Q_CONNECTING;

This state change is very weird, why?

> +	spin_unlock_bh(&queue->state_lock);
> +	nvmet_tcp_schedule_release_queue(queue);
> +	kref_put(&queue->kref, nvmet_tcp_release_queue);
> +}
> +
> +static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
> +{
> +	int ret = -EOPNOTSUPP;
> +	struct tls_handshake_args args;
> +
> +	if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
> +		pr_warn("cannot start TLS in state %d\n", queue->state);
> +		return -EINVAL;
> +	}
> +
> +	kref_get(&queue->kref);
> +	pr_debug("queue %d: TLS ServerHello\n", queue->idx);
> +	memset(&args, 0, sizeof(args));
> +	args.ta_sock = queue->sock;
> +	args.ta_done = nvmet_tcp_tls_handshake_done;
> +	args.ta_data = 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 (ret) {
> +		kref_put(&queue->kref, nvmet_tcp_release_queue);
> +		pr_err("failed to start TLS, err=%d\n", ret);
> +	} else {
> +		queue_delayed_work(nvmet_wq, &queue->tls_handshake_tmo_work,
> +				   tls_handshake_timeout * HZ);
> +	}
> +	return ret;
> +}
> +#endif
> +
>   static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   		struct socket *newsock)
>   {
> @@ -1636,11 +1749,16 @@ static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   
>   	INIT_WORK(&queue->release_work, nvmet_tcp_release_queue_work);
>   	INIT_WORK(&queue->io_work, nvmet_tcp_io_work);
> +	kref_init(&queue->kref);
>   	queue->sock = newsock;
>   	queue->port = port;
>   	queue->nr_cmds = 0;
>   	spin_lock_init(&queue->state_lock);
> -	queue->state = NVMET_TCP_Q_CONNECTING;
> +	if (queue->port->nport->disc_addr.tsas.tcp.sectype ==
> +	    NVMF_TCP_SECTYPE_TLS13)
> +		queue->state = NVMET_TCP_Q_TLS_HANDSHAKE;
> +	else
> +		queue->state = NVMET_TCP_Q_CONNECTING;
>   	INIT_LIST_HEAD(&queue->free_list);
>   	init_llist_head(&queue->resp_list);
>   	INIT_LIST_HEAD(&queue->resp_send_list);
> @@ -1671,6 +1789,25 @@ static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
>   	list_add_tail(&queue->queue_list, &nvmet_tcp_queue_list);
>   	mutex_unlock(&nvmet_tcp_queue_mutex);
>   
> +#ifdef CONFIG_NVME_TARGET_TCP_TLS
> +	INIT_DELAYED_WORK(&queue->tls_handshake_tmo_work,
> +			  nvmet_tcp_tls_handshake_timeout);
> +	if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
> +		struct sock *sk = queue->sock->sk;
> +
> +		/* Restore the default callbacks before starting upcall */
> +		read_lock_bh(&sk->sk_callback_lock);
> +		sk->sk_user_data = NULL;
> +		sk->sk_data_ready = port->data_ready;
> +		read_unlock_bh(&sk->sk_callback_lock);
> +		if (!nvmet_tcp_tls_handshake(queue))
> +			return;
> +
> +		/* TLS handshake failed, terminate the connection */
> +		goto out_destroy_sq;
> +	}
> +#endif
> +
>   	ret = nvmet_tcp_set_queue_sock(queue);
>   	if (ret)
>   		goto out_destroy_sq;

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