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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 7/9] netfilter: nfnetlink_queue: honor NFQA_CFG_F_FAIL_OPEN when netlink unicast fails
Date: Mon, 28 Mar 2016 19:58:00 +0200
Message-ID: <1459187882-5357-8-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1459187882-5357-1-git-send-email-pablo@netfilter.org>

When netlink unicast fails to deliver the message to userspace, we
should also check if the NFQA_CFG_F_FAIL_OPEN flag is set so we reinject
the packet back to the stack.

I think the user expects no packet drops when this flag is set due to
queueing to userspace errors, no matter if related to the internal queue
or when sending the netlink message to userspace.

The userspace application will still get the ENOBUFS error via recvmsg()
so the user still knows that, with the current configuration that is in
place, the userspace application is not consuming the messages at the
pace that the kernel needs.

Reported-by: "Yigal Reiss (yreiss)" <yreiss@cisco.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Tested-by: "Yigal Reiss (yreiss)" <yreiss@cisco.com>
---
 net/netfilter/nfnetlink_queue.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 7542999..cb5b630 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -582,7 +582,12 @@ __nfqnl_enqueue_packet(struct net *net, struct nfqnl_instance *queue,
 	/* nfnetlink_unicast will either free the nskb or add it to a socket */
 	err = nfnetlink_unicast(nskb, net, queue->peer_portid, MSG_DONTWAIT);
 	if (err < 0) {
-		queue->queue_user_dropped++;
+		if (queue->flags & NFQA_CFG_F_FAIL_OPEN) {
+			failopen = 1;
+			err = 0;
+		} else {
+			queue->queue_user_dropped++;
+		}
 		goto err_out_unlock;
 	}
 
-- 
2.1.4


  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-28 17:57 [PATCH 0/9] Netfilter fixes for net Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 1/9] netfilter: ipset: fix race condition in ipset save, swap and delete Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 2/9] openvswitch: Fix checking for new expected connections Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 3/9] openvswitch: call only into reachable nf-nat code Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 4/9] netfilter: x_tables: validate e->target_offset early Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 5/9] netfilter: x_tables: make sure e->next_offset covers remaining blob size Pablo Neira Ayuso
2016-03-28 17:57 ` [PATCH 6/9] netfilter: x_tables: fix unconditional helper Pablo Neira Ayuso
2016-03-28 17:58 ` Pablo Neira Ayuso [this message]
2016-03-28 17:58 ` [PATCH 8/9] netfilter: x_tables: enforce nul-terminated table name from getsockopt GET_ENTRIES Pablo Neira Ayuso
2016-03-28 17:58 ` [PATCH 9/9] netfilter: ipv4: fix NULL dereference Pablo Neira Ayuso
2016-03-28 19:43 ` [PATCH 0/9] Netfilter fixes for net David Miller

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