On 8/18/22 19:59, Dmitry Safonov wrote:
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).
+#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;
}
... snip ...
+#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);
It should always be the case that (rcv_nxt == rcv_sne_seq) and (snd_una
== snd_sne_seq) so the _sne_seq fields are redundant. It's possible to
avoid those extra fields.
However 8 bytes per TCP-AO socket is inconsequential.
--
Regards,
Leonard
