From 931401137f60fc299256bbc221c0b756be31c32c Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 23 Mar 2016 12:58:01 +0100 Subject: [PATCH] netfilter: nfnetlink_queue: honor NFQA_CFG_F_FAIL_OPEN when netlink unicast fails 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)" Signed-off-by: Pablo Neira Ayuso Tested-by: "Yigal Reiss (yreiss)" --- 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 75429997ed41..cb5b630a645b 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; }