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authorPaolo Abeni <pabeni@redhat.com>2017-10-09 14:52:10 +0200
committerDavid S. Miller <davem@davemloft.net>2017-10-09 10:28:25 -0700
commit996b44fcef8f216ea0b6b6e74468c5a77b5e341f (patch)
treee21b0278971b7764f40b74768cb51150c0d3b8c7
parentnetlink: do not set cb_running if dump's start() errs (diff)
downloadlinux-dev-996b44fcef8f216ea0b6b6e74468c5a77b5e341f.tar.xz
linux-dev-996b44fcef8f216ea0b6b6e74468c5a77b5e341f.zip
udp: fix bcast packet reception
The commit bc044e8db796 ("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: Hannes Frederic Sowa <hannes@stressinduktion.org> Fixes: bc044e8db796 ("udp: perform source validation for mcast early demux") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/udp.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5676237d2b0f..e45177ceb0ee 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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,