[PATCH 14/14] nvmet-tcp: control messages for recvmsg()

[Hannes Reinecke <hare@suse.de>]

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>
---
 drivers/nvme/target/tcp.c | 87 +++++++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 13 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 7279c994abd6..e2db573d68d9 100644
--- a/drivers/nvme/target/tcp.c
+++ b/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;
@@ -1116,12 +1118,49 @@ static inline bool nvmet_tcp_pdu_valid(u8 type)
 	return false;
 }
 
+static int nvmet_tcp_tls_record_ok(struct socket *sock, struct msghdr *msg, char *cbuf)
+{
+	struct cmsghdr *cmsg = (struct cmsghdr *)cbuf;
+	u8 ctype, level, description;
+	int ret = 0;
+
+	if (!IS_ENABLED(CONFIG_NVME_TARGET_TCP_TLS))
+		return 0;
+
+	ctype = tls_get_record_type(sock->sk, cmsg);
+	switch (ctype) {
+	case 0:
+		break;
+	case TLS_RECORD_TYPE_DATA:
+		break;
+	case TLS_RECORD_TYPE_ALERT:
+		tls_alert_recv(sock->sk, msg, &level, &description);
+		pr_err("TLS Alert level %u desc %u\n", level, description);
+		ret = (level == TLS_ALERT_LEVEL_FATAL) ?
+			-ENOTCONN : -EAGAIN;
+		break;
+	default:
+		/* discard this record type */
+		pr_err("TLS record %d unhandled\n", 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;
-	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
+	char cbuf[CMSG_LEN(sizeof(char))] = {};
+	struct msghdr msg = {
+#ifdef CONFIG_NVME_TARGET_TCP_TLS
+		.msg_control = cbuf,
+		.msg_controllen = sizeof(cbuf),
+#endif
+		.msg_flags = MSG_DONTWAIT
+	};
 
 recv:
 	iov.iov_base = (void *)&queue->pdu + queue->offset;
@@ -1130,6 +1169,9 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
 			iov.iov_len, msg.msg_flags);
 	if (unlikely(len < 0))
 		return len;
+	ret = nvmet_tcp_tls_record_ok(queue->sock, &msg, cbuf);
+	if (ret < 0)
+		return ret;
 
 	queue->offset += len;
 	queue->left -= len;
@@ -1182,16 +1224,21 @@ 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)
+		if (len <= 0)
+			return len;
+		ret = nvmet_tcp_tls_record_ok(cmd->queue->sock,
+					      &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) {
@@ -1209,20 +1256,30 @@ 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;
-	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
+	int ret, len;
+	char cbuf[CMSG_LEN(sizeof(char))] = {};
+	struct msghdr msg = {
+#ifdef CONFIG_NVME_TARGET_TCP_TLS
+		.msg_control = cbuf,
+		.msg_controllen = sizeof(cbuf),
+#endif
+		.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,
+	len = kernel_recvmsg(queue->sock, &msg, &iov, 1,
 			iov.iov_len, msg.msg_flags);
-	if (unlikely(ret < 0))
+	if (unlikely(len < 0))
+		return len;
+	ret = nvmet_tcp_tls_record_ok(queue->sock, &msg, cbuf);
+	if (ret < 0)
 		return ret;
 
-	queue->offset += ret;
-	queue->left -= ret;
+	queue->offset += len;
+	queue->left -= len;
 	if (queue->left)
 		return -EAGAIN;
 
@@ -1389,6 +1446,10 @@ static int nvmet_tcp_alloc_cmd(struct nvmet_tcp_queue *queue,
 	if (!c->r2t_pdu)
 		goto out_free_data;
 
+	if (IS_ENABLED(CONFIG_NVME_TARGET_TCP_TLS)) {
+		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);
-- 
2.35.3