tcp: Move TCP-AO bits from cookie_v[46]_check() to tcp_ao_syncookie().

We initialise treq->af_specific in cookie_tcp_reqsk_alloc() so that
we can look up a key later in tcp_create_openreq_child().

Initially, that change was added for MD5 by commit ba5a4fdd63ae ("tcp:
make sure treq->af_specific is initialized"), but it has not been used
since commit d0f2b7a9ca0a ("tcp: Disable header prediction for MD5
flow.").

Now, treq->af_specific is used only by TCP-AO, so, we can move that
initialisation into tcp_ao_syncookie().

In addition to that, l3index in cookie_v[46]_check() is only used for
tcp_ao_syncookie(), so let's move it as well.

While at it, we move down tcp_ao_syncookie() in cookie_v4_check() so
that it will be called after security_inet_conn_request() to make
functions order consistent with cookie_v6_check().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231129022924.96156-7-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 18 insertions, 14 deletions

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index de051eb08db8..1e3783c97e28 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -286,9 +286,7 @@ bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt,
 EXPORT_SYMBOL(cookie_ecn_ok);
 
 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
-					    const struct tcp_request_sock_ops *af_ops,
-					    struct sock *sk,
-					    struct sk_buff *skb)
+					    struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_request_sock *treq;
 	struct request_sock *req;
@@ -303,9 +301,6 @@ struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
 
 	treq = tcp_rsk(req);
 
-	/* treq->af_specific might be used to perform TCP_MD5 lookup */
-	treq->af_specific = af_ops;
-
 	treq->syn_tos = TCP_SKB_CB(skb)->ip_dsfield;
 	treq->req_usec_ts = false;
 
@@ -345,7 +340,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	struct rtable *rt;
 	__u8 rcv_wscale;
 	u32 tsoff = 0;
-	int l3index;
 
 	if (!READ_ONCE(net->ipv4.sysctl_tcp_syncookies) ||
 	    !th->ack || th->rst)
@@ -376,8 +370,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	if (!cookie_timestamp_decode(net, &tcp_opt))
 		goto out;
 
-	req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops,
-				     &tcp_request_sock_ipv4_ops, sk, skb);
+	req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops, sk, skb);
 	if (!req)
 		goto out_drop;
 
@@ -406,9 +399,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 
 	ireq->ir_iif = inet_request_bound_dev_if(sk, skb);
 
-	l3index = l3mdev_master_ifindex_by_index(net, ireq->ir_iif);
-	tcp_ao_syncookie(sk, skb, treq, AF_INET, l3index);
-
 	/* We throwed the options of the initial SYN away, so we hope
 	 * the ACK carries the same options again (see RFC1122 4.2.3.8)
 	 */
@@ -417,6 +407,8 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 	if (security_inet_conn_request(sk, skb, req))
 		goto out_free;
 
+	tcp_ao_syncookie(sk, skb, req, AF_INET);
+
 	req->num_retrans = 0;
 
 	/*
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 7696417d0640..c4cd1e09eb6b 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -844,18 +844,30 @@ static struct tcp_ao_key *tcp_ao_inbound_lookup(unsigned short int family,
 }
 
 void tcp_ao_syncookie(struct sock *sk, const struct sk_buff *skb,
-		      struct tcp_request_sock *treq,
-		      unsigned short int family, int l3index)
+		      struct request_sock *req, unsigned short int family)
 {
+	struct tcp_request_sock *treq = tcp_rsk(req);
 	const struct tcphdr *th = tcp_hdr(skb);
 	const struct tcp_ao_hdr *aoh;
 	struct tcp_ao_key *key;
+	int l3index;
+
+	/* treq->af_specific is used to perform TCP_AO lookup
+	 * in tcp_create_openreq_child().
+	 */
+#if IS_ENABLED(CONFIG_IPV6)
+	if (family == AF_INET6)
+		treq->af_specific = &tcp_request_sock_ipv6_ops;
+	else
+#endif
+		treq->af_specific = &tcp_request_sock_ipv4_ops;
 
 	treq->maclen = 0;
 
 	if (tcp_parse_auth_options(th, NULL, &aoh) || !aoh)
 		return;
 
+	l3index = l3mdev_master_ifindex_by_index(sock_net(sk), inet_rsk(req)->ir_iif);
 	key = tcp_ao_inbound_lookup(family, sk, skb, -1, aoh->keyid, l3index);
 	if (!key)
 		/* Key not found, continue without TCP-AO */