[PATCH 15/18] nvmet-tcp: enable TLS handshake upcall

[Hannes Reinecke <hare@suse.de>]

Add functions to start the TLS handshake upcall.

Signed-off-by: Hannes Reincke <hare@suse.de>
---
 drivers/nvme/target/tcp.c | 188 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 181 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 5c43767c5ecd..6e88e98a2c59 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -9,8 +9,10 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/nvme-tcp.h>
+#include <linux/nvme-keyring.h>
 #include <net/sock.h>
 #include <net/tcp.h>
+#include <net/handshake.h>
 #include <linux/inet.h>
 #include <linux/llist.h>
 #include <crypto/hash.h>
@@ -40,6 +42,14 @@ module_param(idle_poll_period_usecs, int, 0644);
 MODULE_PARM_DESC(idle_poll_period_usecs,
 		"nvmet tcp io_work poll till idle time period in usecs");
 
+/*
+ * TLS handshake timeout
+ */
+static int tls_handshake_timeout = 30;
+module_param(tls_handshake_timeout, int, 0644);
+MODULE_PARM_DESC(tls_handshake_timeout,
+		 "nvme TLS handshake timeout in seconds (default 30)");
+
 #define NVMET_TCP_RECV_BUDGET		8
 #define NVMET_TCP_SEND_BUDGET		8
 #define NVMET_TCP_IO_WORK_BUDGET	64
@@ -131,6 +141,9 @@ struct nvmet_tcp_queue {
 	struct ahash_request	*snd_hash;
 	struct ahash_request	*rcv_hash;
 
+	struct key		*tls_psk;
+	struct delayed_work	tls_handshake_work;
+
 	unsigned long           poll_end;
 
 	spinlock_t		state_lock;
@@ -168,6 +181,7 @@ static struct workqueue_struct *nvmet_tcp_wq;
 static const struct nvmet_fabrics_ops nvmet_tcp_ops;
 static void nvmet_tcp_free_cmd(struct nvmet_tcp_cmd *c);
 static void nvmet_tcp_free_cmd_buffers(struct nvmet_tcp_cmd *cmd);
+static void nvmet_tcp_tls_handshake_timeout_work(struct work_struct *work);
 
 static inline u16 nvmet_tcp_cmd_tag(struct nvmet_tcp_queue *queue,
 		struct nvmet_tcp_cmd *cmd)
@@ -1400,6 +1414,8 @@ static void nvmet_tcp_restore_socket_callbacks(struct nvmet_tcp_queue *queue)
 {
 	struct socket *sock = queue->sock;
 
+	if (!sock->sk)
+		return;
 	write_lock_bh(&sock->sk->sk_callback_lock);
 	sock->sk->sk_data_ready =  queue->data_ready;
 	sock->sk->sk_state_change = queue->state_change;
@@ -1448,7 +1464,8 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
 	list_del_init(&queue->queue_list);
 	mutex_unlock(&nvmet_tcp_queue_mutex);
 
-	nvmet_tcp_restore_socket_callbacks(queue);
+	if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE)
+		nvmet_tcp_restore_socket_callbacks(queue);
 	cancel_work_sync(&queue->io_work);
 	/* stop accepting incoming data */
 	queue->rcv_state = NVMET_TCP_RECV_ERR;
@@ -1469,6 +1486,8 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
 	nvmet_tcp_free_cmds(queue);
 	if (queue->hdr_digest || queue->data_digest)
 		nvmet_tcp_free_crypto(queue);
+	if (queue->tls_psk)
+		key_put(queue->tls_psk);
 	ida_free(&nvmet_tcp_queue_ida, queue->idx);
 	page = virt_to_head_page(queue->pf_cache.va);
 	__page_frag_cache_drain(page, queue->pf_cache.pagecnt_bias);
@@ -1481,11 +1500,15 @@ static void nvmet_tcp_data_ready(struct sock *sk)
 
 	trace_sk_data_ready(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);
-	read_unlock_bh(&sk->sk_callback_lock);
+	rcu_read_lock_bh();
+	queue = rcu_dereference_sk_user_data(sk);
+	if (queue->data_ready)
+		queue->data_ready(sk);
+	if (likely(queue) &&
+	    queue->state != NVMET_TCP_Q_TLS_HANDSHAKE)
+		queue_work_on(queue_cpu(queue), nvmet_tcp_wq,
+			      &queue->io_work);
+	rcu_read_unlock_bh();
 }
 
 static void nvmet_tcp_write_space(struct sock *sk)
@@ -1585,13 +1608,139 @@ static int nvmet_tcp_set_queue_sock(struct nvmet_tcp_queue *queue)
 		sock->sk->sk_write_space = nvmet_tcp_write_space;
 		if (idle_poll_period_usecs)
 			nvmet_tcp_arm_queue_deadline(queue);
-		queue_work_on(queue_cpu(queue), nvmet_tcp_wq, &queue->io_work);
+		queue_work_on(queue_cpu(queue), nvmet_tcp_wq,
+			      &queue->io_work);
 	}
 	write_unlock_bh(&sock->sk->sk_callback_lock);
 
 	return ret;
 }
 
+static void nvmet_tcp_tls_data_ready(struct sock *sk)
+{
+	struct socket_wq *wq;
+
+	rcu_read_lock();
+	/* kTLS will change the callback */
+	if (sk->sk_data_ready == nvmet_tcp_tls_data_ready) {
+		wq = rcu_dereference(sk->sk_wq);
+		if (skwq_has_sleeper(wq))
+			wake_up_interruptible_all(&wq->wait);
+	}
+	rcu_read_unlock();
+}
+
+static void nvmet_tcp_tls_handshake_restart(struct nvmet_tcp_queue *queue)
+{
+	spin_lock(&queue->state_lock);
+	if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
+		pr_warn("queue %d: TLS handshake already completed\n",
+			queue->idx);
+		spin_unlock(&queue->state_lock);
+		return;
+	}
+	queue->state = NVMET_TCP_Q_CONNECTING;
+	spin_unlock(&queue->state_lock);
+
+	pr_debug("queue %d: restarting queue after TLS handshake\n",
+		 queue->idx);
+	/*
+	 * Set callbacks after handshake; TLS implementation
+	 * might have changed the socket callbacks.
+	 */
+	nvmet_tcp_set_queue_sock(queue);
+}
+
+static void nvmet_tcp_save_tls_callbacks(struct nvmet_tcp_queue *queue)
+{
+	struct sock *sk = queue->sock->sk;
+
+	write_lock_bh(&sk->sk_callback_lock);
+	rcu_assign_sk_user_data(sk, queue);
+	queue->data_ready = sk->sk_data_ready;
+	sk->sk_data_ready = nvmet_tcp_tls_data_ready;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void nvmet_tcp_restore_tls_callbacks(struct nvmet_tcp_queue *queue)
+{
+	struct sock *sk = queue->sock->sk;
+
+	if (WARN_ON(!sk))
+		return;
+	write_lock_bh(&sk->sk_callback_lock);
+	/* Only reset the callback if it really is ours */
+	if (sk->sk_data_ready == nvmet_tcp_tls_data_ready)
+		sk->sk_data_ready = queue->data_ready;
+	rcu_assign_sk_user_data(sk, NULL);
+	queue->data_ready = NULL;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+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);
+	if (!status) {
+		spin_lock(&queue->state_lock);
+		queue->tls_psk = key_lookup(peerid);
+		if (IS_ERR(queue->tls_psk)) {
+			pr_warn("queue %d: TLS key %x not found\n",
+				queue->idx, peerid);
+			queue->tls_psk = NULL;
+		}
+		spin_unlock(&queue->state_lock);
+	}
+	cancel_delayed_work_sync(&queue->tls_handshake_work);
+	nvmet_tcp_restore_tls_callbacks(queue);
+	if (status)
+		nvmet_tcp_schedule_release_queue(queue);
+	else
+		nvmet_tcp_tls_handshake_restart(queue);
+}
+
+static void nvmet_tcp_tls_handshake_timeout_work(struct work_struct *w)
+{
+	struct nvmet_tcp_queue *queue = container_of(to_delayed_work(w),
+			struct nvmet_tcp_queue, tls_handshake_work);
+
+	pr_debug("queue %d: TLS handshake timeout\n", queue->idx);
+	nvmet_tcp_restore_tls_callbacks(queue);
+	nvmet_tcp_schedule_release_queue(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;
+	}
+
+	pr_debug("queue %d: TLS ServerHello\n", queue->idx);
+	args.ta_sock = queue->sock;
+	args.ta_done = nvmet_tcp_tls_handshake_done;
+	args.ta_data = queue;
+	args.ta_keyring = nvme_keyring_id();
+	args.ta_timeout_ms = tls_handshake_timeout * 2 * 1024;
+
+	ret = tls_server_hello_psk(&args, GFP_KERNEL);
+	if (ret) {
+		pr_err("failed to start TLS, err=%d\n", ret);
+	} else {
+		pr_debug("queue %d wakeup userspace\n", queue->idx);
+		nvmet_tcp_tls_data_ready(queue->sock->sk);
+		queue_delayed_work(nvmet_wq, &queue->tls_handshake_work,
+				   tls_handshake_timeout * HZ);
+	}
+	return ret;
+}
+
 static void nvmet_tcp_alloc_queue(struct nvmet_tcp_port *port,
 		struct socket *newsock)
 {
@@ -1604,6 +1753,8 @@ 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);
+	INIT_DELAYED_WORK(&queue->tls_handshake_work,
+			  nvmet_tcp_tls_handshake_timeout_work);
 	queue->sock = newsock;
 	queue->port = port;
 	queue->nr_cmds = 0;
@@ -1646,6 +1797,29 @@ 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);
 
+	if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
+		nvmet_tcp_save_tls_callbacks(queue);
+		if (!nvmet_tcp_tls_handshake(queue))
+			return;
+		nvmet_tcp_restore_tls_callbacks(queue);
+
+		/*
+		 * If sectype is set to 'tls1.3' TLS is required
+		 * so terminate the connection if the TLS handshake
+		 * failed.
+		 */
+		if (queue->port->nport->disc_addr.tsas.tcp.sectype ==
+		    NVMF_TCP_SECTYPE_TLS13) {
+			pr_debug("queue %d sectype tls1.3, terminate connection\n",
+				 queue->idx);
+			goto out_destroy_sq;
+		}
+		pr_debug("queue %d fallback to icreq\n", queue->idx);
+		spin_lock(&queue->state_lock);
+		queue->state = NVMET_TCP_Q_CONNECTING;
+		spin_unlock(&queue->state_lock);
+	}
+
 	ret = nvmet_tcp_set_queue_sock(queue);
 	if (ret)
 		goto out_destroy_sq;
-- 
2.35.3