From ace45bec6d77bc061c3c3d8ad99e298ea9800c2b Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 30 Mar 2018 21:04:43 +0100
Subject: rxrpc: Fix firewall route keepalive

Fix the firewall route keepalive part of AF_RXRPC which is currently
function incorrectly by replying to VERSION REPLY packets from the server
with VERSION REQUEST packets.

Instead, send VERSION REPLY packets to the peers of service connections to
act as keep-alives 20s after the latest packet was transmitted to that
peer.

Also, just discard VERSION REPLY packets rather than replying to them.

Signed-off-by: David Howells <dhowells@redhat.com>
---
 net/rxrpc/peer_event.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)

(limited to 'net/rxrpc/peer_event.c')

diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index 7f749505e699..d01eb9a06448 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -348,3 +348,99 @@ void rxrpc_peer_add_rtt(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why,
 	trace_rxrpc_rtt_rx(call, why, send_serial, resp_serial, rtt,
 			   usage, avg);
 }
+
+/*
+ * Perform keep-alive pings with VERSION packets to keep any NAT alive.
+ */
+void rxrpc_peer_keepalive_worker(struct work_struct *work)
+{
+	struct rxrpc_net *rxnet =
+		container_of(work, struct rxrpc_net, peer_keepalive_work);
+	struct rxrpc_peer *peer;
+	unsigned long delay;
+	ktime_t base, now = ktime_get_real();
+	s64 diff;
+	u8 cursor, slot;
+
+	base = rxnet->peer_keepalive_base;
+	cursor = rxnet->peer_keepalive_cursor;
+
+	_enter("%u,%lld", cursor, ktime_sub(now, base));
+
+next_bucket:
+	diff = ktime_to_ns(ktime_sub(now, base));
+	if (diff < 0)
+		goto resched;
+
+	_debug("at %u", cursor);
+	spin_lock_bh(&rxnet->peer_hash_lock);
+next_peer:
+	if (!rxnet->live) {
+		spin_unlock_bh(&rxnet->peer_hash_lock);
+		goto out;
+	}
+
+	/* Everything in the bucket at the cursor is processed this second; the
+	 * bucket at cursor + 1 goes now + 1s and so on...
+	 */
+	if (hlist_empty(&rxnet->peer_keepalive[cursor])) {
+		if (hlist_empty(&rxnet->peer_keepalive_new)) {
+			spin_unlock_bh(&rxnet->peer_hash_lock);
+			goto emptied_bucket;
+		}
+
+		hlist_move_list(&rxnet->peer_keepalive_new,
+				&rxnet->peer_keepalive[cursor]);
+	}
+
+	peer = hlist_entry(rxnet->peer_keepalive[cursor].first,
+			   struct rxrpc_peer, keepalive_link);
+	hlist_del_init(&peer->keepalive_link);
+	if (!rxrpc_get_peer_maybe(peer))
+		goto next_peer;
+
+	spin_unlock_bh(&rxnet->peer_hash_lock);
+
+	_debug("peer %u {%pISp}", peer->debug_id, &peer->srx.transport);
+
+recalc:
+	diff = ktime_divns(ktime_sub(peer->last_tx_at, base), NSEC_PER_SEC);
+	if (diff < -30 || diff > 30)
+		goto send; /* LSW of 64-bit time probably wrapped on 32-bit */
+	diff += RXRPC_KEEPALIVE_TIME - 1;
+	if (diff < 0)
+		goto send;
+
+	slot = (diff > RXRPC_KEEPALIVE_TIME - 1) ? RXRPC_KEEPALIVE_TIME - 1 : diff;
+	if (slot == 0)
+		goto send;
+
+	/* A transmission to this peer occurred since last we examined it so
+	 * put it into the appropriate future bucket.
+	 */
+	slot = (slot + cursor) % ARRAY_SIZE(rxnet->peer_keepalive);
+	spin_lock_bh(&rxnet->peer_hash_lock);
+	hlist_add_head(&peer->keepalive_link, &rxnet->peer_keepalive[slot]);
+	rxrpc_put_peer(peer);
+	goto next_peer;
+
+send:
+	rxrpc_send_keepalive(peer);
+	now = ktime_get_real();
+	goto recalc;
+
+emptied_bucket:
+	cursor++;
+	if (cursor >= ARRAY_SIZE(rxnet->peer_keepalive))
+		cursor = 0;
+	base = ktime_add_ns(base, NSEC_PER_SEC);
+	goto next_bucket;
+
+resched:
+	rxnet->peer_keepalive_base = base;
+	rxnet->peer_keepalive_cursor = cursor;
+	delay = nsecs_to_jiffies(-diff) + 1;
+	timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);
+out:
+	_leave("");
+}
-- 
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