nvmet-tcp: control messages for recvmsg()

kTLS requires control messages for recvmsg() to relay any out-of-band
TLS messages (eg TLS alerts) to the caller.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/target/tcp.c

@@ -14,6 +14,7 @@
 #include <net/sock.h>
 #include <net/tcp.h>
 #include <net/tls.h>
+#include <net/tls_prot.h>
 #include <net/handshake.h>
 #include <linux/inet.h>
 #include <linux/llist.h>
@@ -118,6 +119,7 @@ struct nvmet_tcp_cmd {
 	u32				pdu_len;
 	u32				pdu_recv;
 	int				sg_idx;
+	char				recv_cbuf[CMSG_LEN(sizeof(char))];
 	struct msghdr			recv_msg;
 	struct bio_vec			*iov;
 	u32				flags;
@@ -1121,20 +1123,65 @@ static inline bool nvmet_tcp_pdu_valid(u8 type)
 	return false;
 }
 
+static int nvmet_tcp_tls_record_ok(struct nvmet_tcp_queue *queue,
+		struct msghdr *msg, char *cbuf)
+{
+	struct cmsghdr *cmsg = (struct cmsghdr *)cbuf;
+	u8 ctype, level, description;
+	int ret = 0;
+
+	ctype = tls_get_record_type(queue->sock->sk, cmsg);
+	switch (ctype) {
+	case 0:
+		break;
+	case TLS_RECORD_TYPE_DATA:
+		break;
+	case TLS_RECORD_TYPE_ALERT:
+		tls_alert_recv(queue->sock->sk, msg, &level, &description);
+		if (level == TLS_ALERT_LEVEL_FATAL) {
+			pr_err("queue %d: TLS Alert desc %u\n",
+			       queue->idx, description);
+			ret = -ENOTCONN;
+		} else {
+			pr_warn("queue %d: TLS Alert desc %u\n",
+			       queue->idx, description);
+			ret = -EAGAIN;
+		}
+		break;
+	default:
+		/* discard this record type */
+		pr_err("queue %d: TLS record %d unhandled\n",
+		       queue->idx, ctype);
+		ret = -EAGAIN;
+		break;
+	}
+	return ret;
+}
+
 static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
 {
 	struct nvme_tcp_hdr *hdr = &queue->pdu.cmd.hdr;
-	int len;
+	int len, ret;
 	struct kvec iov;
+	char cbuf[CMSG_LEN(sizeof(char))] = {};
 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
 
 recv:
 	iov.iov_base = (void *)&queue->pdu + queue->offset;
 	iov.iov_len = queue->left;
+	if (queue->tls_pskid) {
+		msg.msg_control = cbuf;
+		msg.msg_controllen = sizeof(cbuf);
+	}
 	len = kernel_recvmsg(queue->sock, &msg, &iov, 1,
 			iov.iov_len, msg.msg_flags);
 	if (unlikely(len < 0))
 		return len;
+	if (queue->tls_pskid) {
+		ret = nvmet_tcp_tls_record_ok(queue, &msg, cbuf);
+		if (ret < 0)
+			return ret;
+	}
 
 	queue->offset += len;
 	queue->left -= len;
@@ -1187,16 +1234,22 @@ static void nvmet_tcp_prep_recv_ddgst(struct nvmet_tcp_cmd *cmd)
 static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
 {
 	struct nvmet_tcp_cmd  *cmd = queue->cmd;
-	int ret;
+	int len, ret;
 
 	while (msg_data_left(&cmd->recv_msg)) {
-		ret = sock_recvmsg(cmd->queue->sock, &cmd->recv_msg,
+		len = sock_recvmsg(cmd->queue->sock, &cmd->recv_msg,
 			cmd->recv_msg.msg_flags);
-		if (ret <= 0)
-			return ret;
+		if (len <= 0)
+			return len;
+		if (queue->tls_pskid) {
+			ret = nvmet_tcp_tls_record_ok(cmd->queue,
+					&cmd->recv_msg, cmd->recv_cbuf);
+			if (ret < 0)
+				return ret;
+		}
 
-		cmd->pdu_recv += ret;
-		cmd->rbytes_done += ret;
+		cmd->pdu_recv += len;
+		cmd->rbytes_done += len;
 	}
 
 	if (queue->data_digest) {
@@ -1214,20 +1267,30 @@ static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
 static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
 {
 	struct nvmet_tcp_cmd *cmd = queue->cmd;
-	int ret;
+	int ret, len;
+	char cbuf[CMSG_LEN(sizeof(char))] = {};
 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
 	struct kvec iov = {
 		.iov_base = (void *)&cmd->recv_ddgst + queue->offset,
 		.iov_len = queue->left
 	};
 
-	ret = kernel_recvmsg(queue->sock, &msg, &iov, 1,
+	if (queue->tls_pskid) {
+		msg.msg_control = cbuf;
+		msg.msg_controllen = sizeof(cbuf);
+	}
+	len = kernel_recvmsg(queue->sock, &msg, &iov, 1,
 			iov.iov_len, msg.msg_flags);
-	if (unlikely(ret < 0))
-		return ret;
+	if (unlikely(len < 0))
+		return len;
+	if (queue->tls_pskid) {
+		ret = nvmet_tcp_tls_record_ok(queue, &msg, cbuf);
+		if (ret < 0)
+			return ret;
+	}
 
-	queue->offset += ret;
-	queue->left -= ret;
+	queue->offset += len;
+	queue->left -= len;
 	if (queue->left)
 		return -EAGAIN;
 
@@ -1407,6 +1470,10 @@ static int nvmet_tcp_alloc_cmd(struct nvmet_tcp_queue *queue,
 	if (!c->r2t_pdu)
 		goto out_free_data;
 
+	if (queue->state == NVMET_TCP_Q_TLS_HANDSHAKE) {
+		c->recv_msg.msg_control = c->recv_cbuf;
+		c->recv_msg.msg_controllen = sizeof(c->recv_cbuf);
+	}
 	c->recv_msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
 
 	list_add_tail(&c->entry, &queue->free_list);