[PATCH v1 bpf-next 03/11] tcp: Clean up goto labels in cookie_v[46]_check().

From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	David Ahern <dsahern@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>,
	Kuniyuki Iwashima <kuni1840@gmail.com>, <bpf@vger.kernel.org>,
	<netdev@vger.kernel.org>
Subject: [PATCH v1 bpf-next 03/11] tcp: Clean up goto labels in cookie_v[46]_check().
Date: Fri, 13 Oct 2023 15:04:25 -0700	[thread overview]
Message-ID: <20231013220433.70792-4-kuniyu@amazon.com> (raw)
In-Reply-To: <20231013220433.70792-1-kuniyu@amazon.com>

We will add a SOCK_OPS hook to validate SYN Cookie.

We invoke the hook after allocating reqsk.  In case it fails,
we will respond with RST instead of just dropping the ACK.

Then, there would be more duplicated error handling patterns.
To avoid that, let's clean up goto labels.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.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 64280cf42667..b0cf6f4d66d8 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -369,11 +369,10 @@ 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);
@@ -405,10 +404,8 @@ 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;
 
@@ -425,10 +422,8 @@ 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);
@@ -452,5 +447,10 @@ 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 cbee2df8a006..b8ef6efbb60e 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -171,11 +171,10 @@ 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);
@@ -263,5 +262,6 @@ 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

