Commit 996b44fc authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller

udp: fix bcast packet reception

The commit bc044e8d ("udp: perform source validation for
mcast early demux") does not take into account that broadcast packets
lands in the same code path and they need different checks for the
source address - notably, zero source address are valid for bcast
and invalid for mcast.

As a result, 2nd and later broadcast packets with 0 source address
landing to the same socket are dropped. This breaks dhcp servers.

Since we don't have stringent performance requirements for ingress
broadcast traffic, fix it by disabling UDP early demux such traffic.
Reported-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Fixes: bc044e8d ("udp: perform source validation for mcast early demux")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 41c87425
......@@ -2240,20 +2240,16 @@ int udp_v4_early_demux(struct sk_buff *skb)
iph = ip_hdr(skb);
uh = udp_hdr(skb);
if (skb->pkt_type == PACKET_BROADCAST ||
skb->pkt_type == PACKET_MULTICAST) {
if (skb->pkt_type == PACKET_MULTICAST) {
in_dev = __in_dev_get_rcu(skb->dev);
if (!in_dev)
return 0;
/* we are supposed to accept bcast packets */
if (skb->pkt_type == PACKET_MULTICAST) {
ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
iph->protocol);
if (!ours)
return 0;
}
ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
iph->protocol);
if (!ours)
return 0;
sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
uh->source, iph->saddr,
......
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