netdev - [PATCH net-next 05/10] tcp: pass want_cookie down to req

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Date:   Thu, 30 Jul 2020 19:15:24 +0200
From:   Florian Westphal <fw@...len.de>
To:     <netdev@...r.kernel.org>
Cc:     edumazet@...gle.com, mathew.j.martineau@...ux.intel.com,
        matthieu.baerts@...sares.net, pabeni@...hat.com,
        Florian Westphal <fw@...len.de>
Subject: [PATCH net-next 05/10] tcp: pass want_cookie down to req_init function

In MPTCP case, we want to know if we should store a new token id or if we
should try best-effort only (cookie case).

This allows the MPTCP core to detect when it should elide the storage
of the generated MPTCP token.

Signed-off-by: Florian Westphal <fw@...len.de>
---
 One alternative would be to add a bit in the mptcp request
 socket and use that instead.
 Yet another alternative would be to store the token normally but
 then toss immediately (request sk is discarded right away).

 Let me know if I should evaluate a different approach.

 include/net/tcp.h    |  3 ++-
 net/ipv4/tcp_input.c |  2 +-
 net/ipv4/tcp_ipv4.c  |  3 ++-
 net/ipv6/tcp_ipv6.c  |  3 ++-
 net/mptcp/subflow.c  | 17 ++++++++++-------
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index e0c35d56091f..84d524d92d12 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2019,7 +2019,8 @@ struct tcp_request_sock_ops {
 #endif
 	void (*init_req)(struct request_sock *req,
 			 const struct sock *sk_listener,
-			 struct sk_buff *skb);
+			 struct sk_buff *skb,
+			 bool syncookie_req);
 #ifdef CONFIG_SYN_COOKIES
 	__u32 (*cookie_init_seq)(const struct sk_buff *skb,
 				 __u16 *mss);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fcca58476678..e7dd9280325d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6698,7 +6698,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 	/* Note: tcp_v6_init_req() might override ir_iif for link locals */
 	inet_rsk(req)->ir_iif = inet_request_bound_dev_if(sk, skb);
 
-	af_ops->init_req(req, sk, skb);
+	af_ops->init_req(req, sk, skb, want_cookie);
 
 	if (IS_ENABLED(CONFIG_MPTCP) && want_cookie)
 		tcp_rsk(req)->is_mptcp = 0;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f8913923a6c0..75da59bcb1a3 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1422,7 +1422,8 @@ static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
 
 static void tcp_v4_init_req(struct request_sock *req,
 			    const struct sock *sk_listener,
-			    struct sk_buff *skb)
+			    struct sk_buff *skb,
+			    bool want_cookie)
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	struct net *net = sock_net(sk_listener);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 305870a72352..58e127997e5d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -793,7 +793,8 @@ static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
 
 static void tcp_v6_init_req(struct request_sock *req,
 			    const struct sock *sk_listener,
-			    struct sk_buff *skb)
+			    struct sk_buff *skb,
+			    bool want_cookie)
 {
 	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
 	struct inet_request_sock *ireq = inet_rsk(req);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 9b11d2b6ff4d..e9c7d97251e9 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -113,7 +113,8 @@ static int __subflow_init_req(struct request_sock *req, const struct sock *sk_li
 
 static void subflow_init_req(struct request_sock *req,
 			     const struct sock *sk_listener,
-			     struct sk_buff *skb)
+			     struct sk_buff *skb,
+			     bool want_cookie)
 {
 	struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
@@ -167,25 +168,27 @@ static void subflow_init_req(struct request_sock *req,
 
 static void subflow_v4_init_req(struct request_sock *req,
 				const struct sock *sk_listener,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				bool want_cookie)
 {
 	tcp_rsk(req)->is_mptcp = 1;
 
-	tcp_request_sock_ipv4_ops.init_req(req, sk_listener, skb);
+	tcp_request_sock_ipv4_ops.init_req(req, sk_listener, skb, want_cookie);
 
-	subflow_init_req(req, sk_listener, skb);
+	subflow_init_req(req, sk_listener, skb, want_cookie);
 }
 
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 static void subflow_v6_init_req(struct request_sock *req,
 				const struct sock *sk_listener,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				bool want_cookie)
 {
 	tcp_rsk(req)->is_mptcp = 1;
 
-	tcp_request_sock_ipv6_ops.init_req(req, sk_listener, skb);
+	tcp_request_sock_ipv6_ops.init_req(req, sk_listener, skb, want_cookie);
 
-	subflow_init_req(req, sk_listener, skb);
+	subflow_init_req(req, sk_listener, skb, want_cookie);
 }
 #endif
 
-- 
2.26.2