tcp: Add clean acked data hook

Called when a TCP segment is acknowledged.
Could be used by application protocols who hold additional
metadata associated with the stream data.

This is required by TLS device offload to release
metadata associated with acknowledged TLS records.

Signed-off-by: Ilya Lesokhin <[email protected]>
Signed-off-by: Boris Pismenny <[email protected]>
Signed-off-by: Aviad Yehezkel <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Ilya Lesokhin

include/net/inet_connection_sock.h

@@ -77,6 +77,7 @@ struct inet_connection_sock_af_ops {
  * @icsk_af_ops		   Operations which are AF_INET{4,6} specific
  * @icsk_ulp_ops	   Pluggable ULP control hook
  * @icsk_ulp_data	   ULP private data
+ * @icsk_clean_acked	   Clean acked data hook
  * @icsk_listen_portaddr_node	hash to the portaddr listener hashtable
  * @icsk_ca_state:	   Congestion control state
  * @icsk_retransmits:	   Number of unrecovered [RTO] timeouts
@@ -102,6 +103,7 @@ struct inet_connection_sock {
 	const struct inet_connection_sock_af_ops *icsk_af_ops;
 	const struct tcp_ulp_ops  *icsk_ulp_ops;
 	void			  *icsk_ulp_data;
+	void (*icsk_clean_acked)(struct sock *sk, u32 acked_seq);
 	struct hlist_node         icsk_listen_portaddr_node;
 	unsigned int		  (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
 	__u8			  icsk_ca_state:6,

include/net/tcp.h

@@ -2105,4 +2105,12 @@ static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
 #if IS_ENABLED(CONFIG_SMC)
 extern struct static_key_false tcp_have_smc;
 #endif
+
+#if IS_ENABLED(CONFIG_TLS_DEVICE)
+void clean_acked_data_enable(struct inet_connection_sock *icsk,
+			     void (*cad)(struct sock *sk, u32 ack_seq));
+void clean_acked_data_disable(struct inet_connection_sock *icsk);
+
+#endif
+
 #endif	/* _TCP_H */

net/ipv4/tcp_input.c

@@ -111,6 +111,25 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 #define REXMIT_LOST	1 /* retransmit packets marked lost */
 #define REXMIT_NEW	2 /* FRTO-style transmit of unsent/new packets */
 
+#if IS_ENABLED(CONFIG_TLS_DEVICE)
+static DEFINE_STATIC_KEY_FALSE(clean_acked_data_enabled);
+
+void clean_acked_data_enable(struct inet_connection_sock *icsk,
+			     void (*cad)(struct sock *sk, u32 ack_seq))
+{
+	icsk->icsk_clean_acked = cad;
+	static_branch_inc(&clean_acked_data_enabled);
+}
+EXPORT_SYMBOL_GPL(clean_acked_data_enable);
+
+void clean_acked_data_disable(struct inet_connection_sock *icsk)
+{
+	static_branch_dec(&clean_acked_data_enabled);
+	icsk->icsk_clean_acked = NULL;
+}
+EXPORT_SYMBOL_GPL(clean_acked_data_disable);
+#endif
+
 static void tcp_gro_dev_warn(struct sock *sk, const struct sk_buff *skb,
 			     unsigned int len)
 {
@@ -3560,6 +3579,12 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	if (after(ack, prior_snd_una)) {
 		flag |= FLAG_SND_UNA_ADVANCED;
 		icsk->icsk_retransmits = 0;
+
+#if IS_ENABLED(CONFIG_TLS_DEVICE)
+		if (static_branch_unlikely(&clean_acked_data_enabled))
+			if (icsk->icsk_clean_acked)
+				icsk->icsk_clean_acked(sk, ack);
+#endif
 	}
 
 	prior_fack = tcp_is_sack(tp) ? tcp_highest_sack_seq(tp) : tp->snd_una;