netdev - [PATCH v3 net-next 3/8] tcp: Clean up goto labels in cookie_v[46]

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Date: Tue, 28 Nov 2023 18:29:19 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
CC: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...zon.com>,
	Kuniyuki Iwashima <kuni1840@...il.com>, <netdev@...r.kernel.org>, "Eric
 Dumazet" <edumazert@...gle.com>
Subject: [PATCH v3 net-next 3/8] tcp: Clean up goto labels in cookie_v[46]_check().

We will support arbitrary SYN Cookie with BPF, and then reqsk
will be preallocated before cookie_v[46]_check().

Depending on how validation fails, we send RST or just drop skb.

To make the error handling easier, let's clean up goto labels.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Reviewed-by: Simon Horman <horms@...nel.org>
Reviewed-by: Eric Dumazet <edumazert@...gle.com>
---
 net/ipv4/syncookies.c | 22 +++++++++++-----------
 net/ipv6/syncookies.c |  4 ++--
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index fb41bb18fe6b..8b7d7d7788af 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -376,11 +376,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	if (!cookie_timestamp_decode(net, &tcp_opt))
 		goto out;
 
-	ret = NULL;
 	req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops,
 				     &tcp_request_sock_ipv4_ops, sk, skb);
 	if (!req)
-		goto out;
+		goto out_drop;
 
 	ireq = inet_rsk(req);
 	treq = tcp_rsk(req);
@@ -415,10 +414,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	 */
 	RCU_INIT_POINTER(ireq->ireq_opt, tcp_v4_save_options(net, skb));
 
-	if (security_inet_conn_request(sk, skb, req)) {
-		reqsk_free(req);
-		goto out;
-	}
+	if (security_inet_conn_request(sk, skb, req))
+		goto out_free;
 
 	req->num_retrans = 0;
 
@@ -435,10 +432,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 			   ireq->ir_loc_addr, th->source, th->dest, sk->sk_uid);
 	security_req_classify_flow(req, flowi4_to_flowi_common(&fl4));
 	rt = ip_route_output_key(net, &fl4);
-	if (IS_ERR(rt)) {
-		reqsk_free(req);
-		goto out;
-	}
+	if (IS_ERR(rt))
+		goto out_free;
 
 	/* Try to redo what tcp_v4_send_synack did. */
 	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
@@ -462,5 +457,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	 */
 	if (ret)
 		inet_sk(ret)->cork.fl.u.ip4 = fl4;
-out:	return ret;
+out:
+	return ret;
+out_free:
+	reqsk_free(req);
+out_drop:
+	return NULL;
 }
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index ba394fa73f41..106376cbc9de 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -172,11 +172,10 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	if (!cookie_timestamp_decode(net, &tcp_opt))
 		goto out;
 
-	ret = NULL;
 	req = cookie_tcp_reqsk_alloc(&tcp6_request_sock_ops,
 				     &tcp_request_sock_ipv6_ops, sk, skb);
 	if (!req)
-		goto out;
+		goto out_drop;
 
 	ireq = inet_rsk(req);
 	treq = tcp_rsk(req);
@@ -269,5 +268,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 	return ret;
 out_free:
 	reqsk_free(req);
+out_drop:
 	return NULL;
 }
-- 
2.30.2