Re: [PATCH v2 08/17] net: psp: add socket security association code

Daniel Zahka wrote:

From: Jakub Kicinski <kuba@kernel.org>

Add the ability to install PSP Rx and Tx crypto keys on TCP
connections. Netlink ops are provided for both operations.
Rx side combines allocating a new Rx key and installing it
on the socket. Theoretically these are separate actions,
but in practice they will always be used one after the
other. We can add distinct "alloc" and "install" ops later.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Co-developed-by: Daniel Zahka <daniel.zahka@gmail.com>

+static inline bool psp_is_nondata(struct sk_buff *skb, struct psp_assoc *pas)
+{
+	bool fin = !!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN);
+	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+	u32 seq = TCP_SKB_CB(skb)->seq;
+	bool pure_fin;
+
+	pure_fin = fin && end_seq - seq == 1;
+
+	return seq == end_seq || (pure_fin && seq == pas->upgrade_seq);
+}

Minor: with that test against pas->upgrade_seq this function does more
than its name implies. Maybe psp_is_allowed_nondata_at_upgrade or so.