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udp: Increment UDP_MIB_IGNOREDMULTI for arriving unmatched multicasts

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As NIC multicast filtering isn't perfect, and some platforms are
quite content to spew broadcasts, we should not trigger an event
for skb:kfree_skb when we do not have a match for such an incoming
datagram.  We do though want to avoid sweeping the matter under the
rug entirely, so increment a suitable statistic.

This incorporates feedback from David L. Stevens, Karl Neiss and Eric
Dumazet.

V3 - use bool per David Miller

Signed-off-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rick Jones
2014-11-06 10:37:54 -08:00
committed by David S. Miller
parent f46ad73ac6
commit 36cbb2452c
5 changed files with 20 additions and 6 deletions
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12
net/ipv4/udp.c
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@@ -1647,7 +1647,8 @@ static void udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst)
static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
struct udphdr *uh,
__be32 saddr, __be32 daddr,
struct udp_table *udptable)
struct udp_table *udptable,
int proto)
{
struct sock *sk, *stack[256 / sizeof(struct sock *)];
struct hlist_nulls_node *node;
@@ -1656,6 +1657,7 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
int dif = skb->dev->ifindex;
unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node);
unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
bool inner_flushed = false;
if (use_hash2) {
hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
@@ -1674,6 +1676,7 @@ start_lookup:
dif, hnum)) {
if (unlikely(count == ARRAY_SIZE(stack))) {
flush_stack(stack, count, skb, ~0);
inner_flushed = true;
count = 0;
}
stack[count++] = sk;
@@ -1695,7 +1698,10 @@ start_lookup:
if (count) {
flush_stack(stack, count, skb, count - 1);
} else {
kfree_skb(skb);
if (!inner_flushed)
UDP_INC_STATS_BH(net, UDP_MIB_IGNOREDMULTI,
proto == IPPROTO_UDPLITE);
consume_skb(skb);
}
return 0;
}
@@ -1781,7 +1787,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
return __udp4_lib_mcast_deliver(net, skb, uh,
saddr, daddr, udptable);
saddr, daddr, udptable, proto);
sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
if (sk != NULL) {