From: Geliang Tang <tanggeliang@kylinos.cn>

To extend MPTCP support based on TCP TLS, a tls_prot_ops structure has
been introduced for TLS, encapsulating TCP-specific helpers within this
structure.

Add registering, validating and finding functions for this structure to
add, validate and find a tls_prot_ops on the global list tls_prot_ops_list.

Register TCP-specific structure tls_tcp_ops in tls_init().

Co-developed-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/tls.h  | 18 ++++++++++++
 net/tls/tls_main.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)

diff --git a/include/net/tls.h b/include/net/tls.h
index ebd2550280ae..5f730fb6e801 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -220,6 +220,24 @@ struct tls_prot_info {
 	u16 tail_size;
 };
 
+struct tls_prot_ops {
+	int			protocol;
+	struct module		*owner;
+	struct list_head	list;
+
+	int (*inq)(struct sock *sk);
+	int (*sendmsg_locked)(struct sock *sk, struct msghdr *msg, size_t size);
+	struct sk_buff *(*recv_skb)(struct sock *sk, u32 seq, u32 *off);
+	void (*read_done)(struct sock *sk, size_t len);
+	u32 (*get_skb_seq)(struct sk_buff *skb);
+	int (*read_sock)(struct sock *sk, read_descriptor_t *desc,
+			 sk_read_actor_t recv_actor);
+	__poll_t (*poll)(struct file *file, struct socket *sock,
+			 struct poll_table_struct *wait);
+	bool (*epollin_ready)(const struct sock *sk, int target);
+	void (*check_app_limited)(struct sock *sk);
+};
+
 struct tls_context {
 	/* read-only cache line */
 	struct tls_prot_info prot_info;
diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 56ce0bc8317b..525f0641d3d0 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -128,6 +128,24 @@ static struct proto_ops tls_proto_ops[TLS_NUM_PROTS][TLS_NUM_CONFIG][TLS_NUM_CON
 static void build_protos(struct proto prot[TLS_NUM_CONFIG][TLS_NUM_CONFIG],
 			 const struct proto *base);
 
+static DEFINE_SPINLOCK(tls_prot_ops_lock);
+static LIST_HEAD(tls_prot_ops_list);
+
+/* Must be called with rcu read lock held */
+static struct tls_prot_ops *tls_prot_ops_find(int protocol)
+{
+	struct tls_prot_ops *ops, *ret = NULL;
+
+	list_for_each_entry_rcu(ops, &tls_prot_ops_list, list) {
+		if (ops->protocol == protocol) {
+			ret = ops;
+			break;
+		}
+	}
+
+	return ret;
+}
+
 void update_sk_prot(struct sock *sk, struct tls_context *ctx)
 {
 	int ip_ver = sk->sk_family == AF_INET6 ? TLSV6 : TLSV4;
@@ -1236,6 +1254,58 @@ static struct tcp_ulp_ops tcp_tls_ulp_ops __read_mostly = {
 	.get_info_size		= tls_get_info_size,
 };
 
+static int tls_validate_prot_ops(const struct tls_prot_ops *ops)
+{
+	if (!ops->inq || !ops->sendmsg_locked ||
+	    !ops->recv_skb || !ops->read_done ||
+	    !ops->get_skb_seq || !ops->read_sock ||
+	    !ops->poll || !ops->epollin_ready ||
+	    !ops->check_app_limited) {
+		pr_err("%d does not implement required ops\n", ops->protocol);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int tls_register_prot_ops(struct tls_prot_ops *ops)
+{
+	int ret;
+
+	ret = tls_validate_prot_ops(ops);
+	if (ret)
+		return ret;
+
+	spin_lock(&tls_prot_ops_lock);
+	if (tls_prot_ops_find(ops->protocol)) {
+		spin_unlock(&tls_prot_ops_lock);
+		return -EEXIST;
+	}
+	list_add_tail_rcu(&ops->list, &tls_prot_ops_list);
+	spin_unlock(&tls_prot_ops_lock);
+
+	pr_debug("tls_prot_ops %d registered\n", ops->protocol);
+	return 0;
+}
+
+static u32 tcp_get_skb_seq(struct sk_buff *skb)
+{
+	return TCP_SKB_CB(skb)->seq;
+}
+
+static struct tls_prot_ops tls_tcp_ops = {
+	.protocol		= IPPROTO_TCP,
+	.inq			= tcp_inq,
+	.sendmsg_locked		= tcp_sendmsg_locked,
+	.recv_skb		= tcp_recv_skb,
+	.read_done		= tcp_read_done,
+	.get_skb_seq		= tcp_get_skb_seq,
+	.read_sock		= tcp_read_sock,
+	.poll			= tcp_poll,
+	.epollin_ready		= tcp_epollin_ready,
+	.check_app_limited	= tcp_rate_check_app_limited,
+};
+
 static int __init tls_register(void)
 {
 	int err;
@@ -1254,6 +1324,8 @@ static int __init tls_register(void)
 
 	tcp_register_ulp(&tcp_tls_ulp_ops);
 
+	tls_register_prot_ops(&tls_tcp_ops);
+
 	return 0;
 err_strp:
 	tls_strp_dev_exit();
-- 
2.51.0