tcp: fix passive TFO socket having invalid NAPI ID

[ Upstream commit dbe0ca8 ]

There is a bug with passive TFO sockets returning an invalid NAPI ID 0
from SO_INCOMING_NAPI_ID. Normally this is not an issue, but zero copy
receive relies on a correct NAPI ID to process sockets on the right
queue.

Fix by adding a sk_mark_napi_id_set().

Fixes: e590745 ("tcp: Record Rx hash and NAPI ID in tcp_child_process")
Signed-off-by: David Wei <dw@davidwei.uk>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250617212102.175711-5-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: spikeh

net/ipv4/tcp_fastopen.c

@@ -3,6 +3,7 @@
 #include <linux/tcp.h>
 #include <linux/rcupdate.h>
 #include <net/tcp.h>
+#include <net/busy_poll.h>
 
 void tcp_fastopen_init_key_once(struct net *net)
 {
@@ -279,6 +280,8 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk,
 
 	refcount_set(&req->rsk_refcnt, 2);
 
+	sk_mark_napi_id_set(child, skb);
+
 	/* Now finish processing the fastopen child socket. */
 	tcp_init_transfer(child, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB, skb);