From 05e59e5fb0064c97a1c10921ecd549f2d4a58565 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:14:40 +0000
Subject: [PATCH] add REDIRECT

---
 kernel/net/mptcp/subflow.c |   77 +++++++++++++++++++++++++++++---------
 1 files changed, 58 insertions(+), 19 deletions(-)

diff --git a/kernel/net/mptcp/subflow.c b/kernel/net/mptcp/subflow.c
index 2e92384..6075192 100644
--- a/kernel/net/mptcp/subflow.c
+++ b/kernel/net/mptcp/subflow.c
@@ -40,7 +40,6 @@
 		sock_put((struct sock *)subflow_req->msk);
 
 	mptcp_token_destroy_request(req);
-	tcp_request_sock_ops.destructor(req);
 }
 
 static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
@@ -276,7 +275,6 @@
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 	struct sock *sk = subflow->conn;
 
-	tcp_set_state(ssk, TCP_CLOSE);
 	tcp_send_active_reset(ssk, GFP_ATOMIC);
 	tcp_done(ssk);
 	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
@@ -359,9 +357,8 @@
 	mptcp_subflow_reset(sk);
 }
 
-struct request_sock_ops mptcp_subflow_request_sock_ops;
-EXPORT_SYMBOL_GPL(mptcp_subflow_request_sock_ops);
-static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
+static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
+static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
 
 static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
@@ -373,7 +370,7 @@
 	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 		goto drop;
 
-	return tcp_conn_request(&mptcp_subflow_request_sock_ops,
+	return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
 				&subflow_request_sock_ipv4_ops,
 				sk, skb);
 drop:
@@ -381,10 +378,17 @@
 	return 0;
 }
 
+static void subflow_v4_req_destructor(struct request_sock *req)
+{
+	subflow_req_destructor(req);
+	tcp_request_sock_ops.destructor(req);
+}
+
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
-static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
-static struct inet_connection_sock_af_ops subflow_v6_specific;
-static struct inet_connection_sock_af_ops subflow_v6m_specific;
+static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
+static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
+static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
+static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
 
 static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 {
@@ -403,14 +407,35 @@
 		return 0;
 	}
 
-	return tcp_conn_request(&mptcp_subflow_request_sock_ops,
+	return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
 				&subflow_request_sock_ipv6_ops, sk, skb);
 
 drop:
 	tcp_listendrop(sk);
 	return 0; /* don't send reset */
 }
+
+static void subflow_v6_req_destructor(struct request_sock *req)
+{
+	subflow_req_destructor(req);
+	tcp6_request_sock_ops.destructor(req);
+}
 #endif
+
+struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
+					       struct sock *sk_listener,
+					       bool attach_listener)
+{
+	if (ops->family == AF_INET)
+		ops = &mptcp_subflow_v4_request_sock_ops;
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	else if (ops->family == AF_INET6)
+		ops = &mptcp_subflow_v6_request_sock_ops;
+#endif
+
+	return inet_reqsk_alloc(ops, sk_listener, attach_listener);
+}
+EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
 
 /* validate hmac received in third ACK */
 static bool subflow_hmac_valid(const struct request_sock *req,
@@ -636,7 +661,7 @@
 	return child;
 }
 
-static struct inet_connection_sock_af_ops subflow_specific;
+static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
 
 enum mapping_status {
 	MAPPING_OK,
@@ -1017,7 +1042,7 @@
 	}
 }
 
-static struct inet_connection_sock_af_ops *
+static const struct inet_connection_sock_af_ops *
 subflow_default_af_ops(struct sock *sk)
 {
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
@@ -1032,7 +1057,7 @@
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
-	struct inet_connection_sock_af_ops *target;
+	const struct inet_connection_sock_af_ops *target;
 
 	target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
 
@@ -1377,7 +1402,6 @@
 static int subflow_ops_init(struct request_sock_ops *subflow_ops)
 {
 	subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
-	subflow_ops->slab_name = "request_sock_subflow";
 
 	subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
 					      subflow_ops->obj_size, 0,
@@ -1387,16 +1411,17 @@
 	if (!subflow_ops->slab)
 		return -ENOMEM;
 
-	subflow_ops->destructor = subflow_req_destructor;
-
 	return 0;
 }
 
 void __init mptcp_subflow_init(void)
 {
-	mptcp_subflow_request_sock_ops = tcp_request_sock_ops;
-	if (subflow_ops_init(&mptcp_subflow_request_sock_ops) != 0)
-		panic("MPTCP: failed to init subflow request sock ops\n");
+	mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
+	mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
+	mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
+
+	if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
+		panic("MPTCP: failed to init subflow v4 request sock ops\n");
 
 	subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
 	subflow_request_sock_ipv4_ops.init_req = subflow_v4_init_req;
@@ -1407,6 +1432,20 @@
 	subflow_specific.sk_rx_dst_set = subflow_finish_connect;
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
+	/* In struct mptcp_subflow_request_sock, we assume the TCP request sock
+	 * structures for v4 and v6 have the same size. It should not changed in
+	 * the future but better to make sure to be warned if it is no longer
+	 * the case.
+	 */
+	BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
+
+	mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
+	mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
+	mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
+
+	if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
+		panic("MPTCP: failed to init subflow v6 request sock ops\n");
+
 	subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
 	subflow_request_sock_ipv6_ops.init_req = subflow_v6_init_req;
 

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