linux-kernel - [PATCH 19/31] net/tcp: Add TCP-AO SNE support

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Message-Id: <20220818170005.747015-20-dima@arista.com>
Date:   Thu, 18 Aug 2022 17:59:53 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <dima@...sta.com>,
        Andy Lutomirski <luto@...capital.net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Bob Gilligan <gilligan@...sta.com>,
        David Ahern <dsahern@...nel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Francesco Ruggeri <fruggeri@...sta.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Ivan Delalande <colona@...sta.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Leonard Crestez <cdleonard@...il.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Salam Noureddine <noureddine@...sta.com>,
        Shuah Khan <shuah@...nel.org>, netdev@...r.kernel.org,
        linux-crypto@...r.kernel.org
Subject: [PATCH 19/31] net/tcp: Add TCP-AO SNE support

Add Sequence Number Extension (SNE) extension for TCP-AO.
This is needed to protect long-living TCP-AO connections from replaying
attacks after sequence number roll-over, see RFC5925 (6.2).

Co-developed-by: Francesco Ruggeri <fruggeri@...sta.com>
Signed-off-by: Francesco Ruggeri <fruggeri@...sta.com>
Co-developed-by: Salam Noureddine <noureddine@...sta.com>
Signed-off-by: Salam Noureddine <noureddine@...sta.com>
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 net/ipv4/tcp_input.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b8175ded8a70..8d326994d1a1 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3516,9 +3516,21 @@ static inline bool tcp_may_update_window(const struct tcp_sock *tp,
 static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
 {
 	u32 delta = ack - tp->snd_una;
+#ifdef CONFIG_TCP_AO
+	struct tcp_ao_info *ao;
+#endif
 
 	sock_owned_by_me((struct sock *)tp);
 	tp->bytes_acked += delta;
+#ifdef CONFIG_TCP_AO
+	ao = rcu_dereference_protected(tp->ao_info,
+				       lockdep_sock_is_held((struct sock *)tp));
+	if (ao) {
+		if (ack < ao->snd_sne_seq)
+			ao->snd_sne++;
+		ao->snd_sne_seq = ack;
+	}
+#endif
 	tp->snd_una = ack;
 }
 
@@ -3526,9 +3538,21 @@ static void tcp_snd_una_update(struct tcp_sock *tp, u32 ack)
 static void tcp_rcv_nxt_update(struct tcp_sock *tp, u32 seq)
 {
 	u32 delta = seq - tp->rcv_nxt;
+#ifdef CONFIG_TCP_AO
+	struct tcp_ao_info *ao;
+#endif
 
 	sock_owned_by_me((struct sock *)tp);
 	tp->bytes_received += delta;
+#ifdef CONFIG_TCP_AO
+	ao = rcu_dereference_protected(tp->ao_info,
+				       lockdep_sock_is_held((struct sock *)tp));
+	if (ao) {
+		if (seq < ao->rcv_sne_seq)
+			ao->rcv_sne++;
+		ao->rcv_sne_seq = seq;
+	}
+#endif
 	WRITE_ONCE(tp->rcv_nxt, seq);
 }
 
@@ -6344,6 +6368,17 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		 * simultaneous connect with crossed SYNs.
 		 * Particularly, it can be connect to self.
 		 */
+#ifdef CONFIG_TCP_AO
+		struct tcp_ao_info *ao;
+
+		ao = rcu_dereference_protected(tp->ao_info,
+					       lockdep_sock_is_held(sk));
+		if (ao) {
+			ao->risn = th->seq;
+			ao->rcv_sne = 0;
+			ao->rcv_sne_seq = ntohl(th->seq);
+		}
+#endif
 		tcp_set_state(sk, TCP_SYN_RECV);
 
 		if (tp->rx_opt.saw_tstamp) {
-- 
2.37.2