[PATCH 16/18] nvmet-tcp: enable TLS handshake upcall

[Hannes Reinecke <hare@suse.de>]

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@suse.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);
+		queue->state = NVMET_TCP_Q_CONNECTING;
+	}
 	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);
 	}
 	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 (!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;
+	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;
-- 
2.35.3