From cc4f9d62037ebcb811f4908bba2986c01df1bd50 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Sat, 29 Jan 2022 17:47:00 +0100
Subject: [PATCH] netfilter: conntrack: move synack init code to helper
Git-commit: cc4f9d62037ebcb811f4908bba2986c01df1bd50
Patch-mainline: v5.17-rc4
References: bsc#1199035

It seems more readable to use a common helper in the followup fix rather
than copypaste or goto.

No functional change intended.  The function is only called for syn-ack
or syn in repy direction in case of simultaneous open.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Ali Abdallah <ali.abdallah@suse.com>
---
 net/netfilter/nf_conntrack_proto_tcp.c |   47 ++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 18 deletions(-)

--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -497,6 +497,32 @@ static void tcp_sack(const struct sk_buf
 	}
 }
 
+static void tcp_init_sender(struct ip_ct_tcp_state *sender,
+			    struct ip_ct_tcp_state *receiver,
+			    const struct sk_buff *skb,
+			    unsigned int dataoff,
+			    const struct tcphdr *tcph,
+			    u32 end, u32 win)
+{
+	/* SYN-ACK in reply to a SYN
+	 * or SYN from reply direction in simultaneous open.
+	 */
+	sender->td_end =
+	sender->td_maxend = end;
+	sender->td_maxwin = (win == 0 ? 1 : win);
+
+	tcp_options(skb, dataoff, tcph, sender);
+	/* RFC 1323:
+	 * Both sides must send the Window Scale option
+	 * to enable window scaling in either direction.
+	 */
+	if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
+	      receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE)) {
+		sender->td_scale = 0;
+		receiver->td_scale = 0;
+	}
+}
+
 static bool tcp_in_window(const struct nf_conn *ct,
 			  struct ip_ct_tcp *state,
 			  enum ip_conntrack_dir dir,
@@ -548,24 +574,9 @@ static bool tcp_in_window(const struct n
 		 * Initialize sender data.
 		 */
 		if (tcph->syn) {
-			/*
-			 * SYN-ACK in reply to a SYN
-			 * or SYN from reply direction in simultaneous open.
-			 */
-			sender->td_end =
-			sender->td_maxend = end;
-			sender->td_maxwin = (win == 0 ? 1 : win);
-
-			tcp_options(skb, dataoff, tcph, sender);
-			/*
-			 * RFC 1323:
-			 * Both sides must send the Window Scale option
-			 * to enable window scaling in either direction.
-			 */
-			if (!(sender->flags & IP_CT_TCP_FLAG_WINDOW_SCALE
-			      && receiver->flags & IP_CT_TCP_FLAG_WINDOW_SCALE))
-				sender->td_scale =
-				receiver->td_scale = 0;
+			tcp_init_sender(sender, receiver,
+					skb, dataoff, tcph,
+					end, win);
 			if (!tcph->ack)
 				/* Simultaneous open */
 				return true;