udp: Increment UDP_MIB_IGNOREDMULTI for arriving unmatched multicasts

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>

diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index df40137..30f541b 100644 (file)
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -156,6 +156,7 @@ enum
        UDP_MIB_RCVBUFERRORS,                   /* RcvbufErrors */
        UDP_MIB_SNDBUFERRORS,                   /* SndbufErrors */
        UDP_MIB_CSUMERRORS,                     /* InCsumErrors */
+       UDP_MIB_IGNOREDMULTI,                   /* IgnoredMulti */
        __UDP_MIB_MAX
 };
 

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index f0d4eb8..6513ade 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -181,6 +181,7 @@ static const struct snmp_mib snmp4_udp_list[] = {
        SNMP_MIB_ITEM("RcvbufErrors", UDP_MIB_RCVBUFERRORS),
        SNMP_MIB_ITEM("SndbufErrors", UDP_MIB_SNDBUFERRORS),
        SNMP_MIB_ITEM("InCsumErrors", UDP_MIB_CSUMERRORS),
+       SNMP_MIB_ITEM("IgnoredMulti", UDP_MIB_IGNOREDMULTI),
        SNMP_MIB_SENTINEL
 };
 

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index df19027..5d0fdca 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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) {

diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index 1752cd0..679253d 100644 (file)
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -136,6 +136,7 @@ static const struct snmp_mib snmp6_udp6_list[] = {
        SNMP_MIB_ITEM("Udp6RcvbufErrors", UDP_MIB_RCVBUFERRORS),
        SNMP_MIB_ITEM("Udp6SndbufErrors", UDP_MIB_SNDBUFERRORS),
        SNMP_MIB_ITEM("Udp6InCsumErrors", UDP_MIB_CSUMERRORS),
+       SNMP_MIB_ITEM("Udp6IgnoredMulti", UDP_MIB_IGNOREDMULTI),
        SNMP_MIB_SENTINEL
 };
 

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 9b68092..b756355 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -771,7 +771,7 @@ static void udp6_csum_zero_error(struct sk_buff *skb)
  */
 static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
                const struct in6_addr *saddr, const struct in6_addr *daddr,
-               struct udp_table *udptable)
+               struct udp_table *udptable, int proto)
 {
        struct sock *sk, *stack[256 / sizeof(struct sock *)];
        const struct udphdr *uh = udp_hdr(skb);
@@ -781,6 +781,7 @@ static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
        int dif = inet6_iif(skb);
        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 = udp6_portaddr_hash(net, &in6addr_any, hnum) &
@@ -803,6 +804,7 @@ start_lookup:
                    (uh->check || udp_sk(sk)->no_check6_rx)) {
                        if (unlikely(count == ARRAY_SIZE(stack))) {
                                flush_stack(stack, count, skb, ~0);
+                               inner_flushed = true;
                                count = 0;
                        }
                        stack[count++] = sk;
@@ -821,7 +823,10 @@ 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;
 }
@@ -873,7 +878,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
         */
        if (ipv6_addr_is_multicast(daddr))
                return __udp6_lib_mcast_deliver(net, skb,
-                               saddr, daddr, udptable);
+                               saddr, daddr, udptable, proto);
 
        /* Unicast */