net: Add MIB counters for checksum errors

Add MIB counters for checksum errors in IP layer,
and TCP/UDP/ICMP layers, to help diagnose problems.

$ nstat -a | grep  Csum
IcmpInCsumErrors                72                 0.0
TcpInCsumErrors                 382                0.0
UdpInCsumErrors                 463221             0.0
Icmp6InCsumErrors               75                 0.0
Udp6InCsumErrors                173442             0.0
IpExtInCsumErrors               10884              0.0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 32 insertions, 16 deletions

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 2a53a79..b4ff0a4 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -699,7 +699,7 @@ static int icmpv6_rcv(struct sk_buff *skb)
 		if (__skb_checksum_complete(skb)) {
 			LIMIT_NETDEBUG(KERN_DEBUG "ICMPv6 checksum failed [%pI6 > %pI6]\n",
 				       saddr, daddr);
-			goto discard_it;
+			goto csum_error;
 		}
 	}
 
@@ -785,6 +785,8 @@ static int icmpv6_rcv(struct sk_buff *skb)
 	kfree_skb(skb);
 	return 0;
 
+csum_error:
+	ICMP6_INC_STATS_BH(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
 discard_it:
 	ICMP6_INC_STATS_BH(dev_net(dev), idev, ICMP6_MIB_INERRORS);
 drop_no_count:
diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c
index bbbe53a..115cc58 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -90,6 +90,7 @@ static const struct snmp_mib snmp6_ipstats_list[] = {
 	SNMP_MIB_ITEM("Ip6OutMcastOctets", IPSTATS_MIB_OUTMCASTOCTETS),
 	SNMP_MIB_ITEM("Ip6InBcastOctets", IPSTATS_MIB_INBCASTOCTETS),
 	SNMP_MIB_ITEM("Ip6OutBcastOctets", IPSTATS_MIB_OUTBCASTOCTETS),
+	SNMP_MIB_ITEM("InCsumErrors", IPSTATS_MIB_CSUMERRORS),
 	SNMP_MIB_SENTINEL
 };
 
@@ -99,6 +100,7 @@ static const struct snmp_mib snmp6_icmp6_list[] = {
 	SNMP_MIB_ITEM("Icmp6InErrors", ICMP6_MIB_INERRORS),
 	SNMP_MIB_ITEM("Icmp6OutMsgs", ICMP6_MIB_OUTMSGS),
 	SNMP_MIB_ITEM("Icmp6OutErrors", ICMP6_MIB_OUTERRORS),
+	SNMP_MIB_ITEM("Icmp6InCsumErrors", ICMP6_MIB_CSUMERRORS),
 	SNMP_MIB_SENTINEL
 };
 
@@ -129,6 +131,7 @@ static const struct snmp_mib snmp6_udp6_list[] = {
 	SNMP_MIB_ITEM("Udp6OutDatagrams", UDP_MIB_OUTDATAGRAMS),
 	SNMP_MIB_ITEM("Udp6RcvbufErrors", UDP_MIB_RCVBUFERRORS),
 	SNMP_MIB_ITEM("Udp6SndbufErrors", UDP_MIB_SNDBUFERRORS),
+	SNMP_MIB_ITEM("Udp6InCsumErrors", UDP_MIB_CSUMERRORS),
 	SNMP_MIB_SENTINEL
 };
 
@@ -139,6 +142,7 @@ static const struct snmp_mib snmp6_udplite6_list[] = {
 	SNMP_MIB_ITEM("UdpLite6OutDatagrams", UDP_MIB_OUTDATAGRAMS),
 	SNMP_MIB_ITEM("UdpLite6RcvbufErrors", UDP_MIB_RCVBUFERRORS),
 	SNMP_MIB_ITEM("UdpLite6SndbufErrors", UDP_MIB_SNDBUFERRORS),
+	SNMP_MIB_ITEM("UdpLite6InCsumErrors", UDP_MIB_CSUMERRORS),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index e51bd1a..7116706 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1405,6 +1405,7 @@ discard:
 	kfree_skb(skb);
 	return 0;
 csum_err:
+	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
 	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
 	goto discard;
 
@@ -1466,7 +1467,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
 		goto discard_it;
 
 	if (!skb_csum_unnecessary(skb) && tcp_v6_checksum_init(skb))
-		goto bad_packet;
+		goto csum_error;
 
 	th = tcp_hdr(skb);
 	hdr = ipv6_hdr(skb);
@@ -1530,6 +1531,8 @@ no_tcp_socket:
 		goto discard_it;
 
 	if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) {
+csum_error:
+		TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
 bad_packet:
 		TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
 	} else {
@@ -1537,11 +1540,6 @@ bad_packet:
 	}
 
 discard_it:
-
-	/*
-	 *	Discard frame
-	 */
-
 	kfree_skb(skb);
 	return 0;
 
@@ -1555,10 +1553,13 @@ do_time_wait:
 		goto discard_it;
 	}
 
-	if (skb->len < (th->doff<<2) || tcp_checksum_complete(skb)) {
-		TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
+	if (skb->len < (th->doff<<2)) {
 		inet_twsk_put(inet_twsk(sk));
-		goto discard_it;
+		goto bad_packet;
+	}
+	if (tcp_checksum_complete(skb)) {
+		inet_twsk_put(inet_twsk(sk));
+		goto csum_error;
 	}
 
 	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index da6019b..d4defdd 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -483,12 +483,17 @@ out:
 csum_copy_err:
 	slow = lock_sock_fast(sk);
 	if (!skb_kill_datagram(sk, skb, flags)) {
-		if (is_udp4)
+		if (is_udp4) {
+			UDP_INC_STATS_USER(sock_net(sk),
+					UDP_MIB_CSUMERRORS, is_udplite);
 			UDP_INC_STATS_USER(sock_net(sk),
 					UDP_MIB_INERRORS, is_udplite);
-		else
+		} else {
+			UDP6_INC_STATS_USER(sock_net(sk),
+					UDP_MIB_CSUMERRORS, is_udplite);
 			UDP6_INC_STATS_USER(sock_net(sk),
 					UDP_MIB_INERRORS, is_udplite);
+		}
 	}
 	unlock_sock_fast(sk, slow);
 
@@ -637,7 +642,7 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 
 	if (rcu_access_pointer(sk->sk_filter)) {
 		if (udp_lib_checksum_complete(skb))
-			goto drop;
+			goto csum_error;
 	}
 
 	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf))
@@ -656,6 +661,8 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	bh_unlock_sock(sk);
 
 	return rc;
+csum_error:
+	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_CSUMERRORS, is_udplite);
 drop:
 	UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
 	atomic_inc(&sk->sk_drops);
@@ -817,7 +824,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	}
 
 	if (udp6_csum_init(skb, uh, proto))
-		goto discard;
+		goto csum_error;
 
 	/*
 	 *	Multicast receive code
@@ -850,7 +857,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 		goto discard;
 
 	if (udp_lib_checksum_complete(skb))
-		goto discard;
+		goto csum_error;
 
 	UDP6_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
 	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
@@ -867,7 +874,9 @@ short_packet:
 		       skb->len,
 		       daddr,
 		       ntohs(uh->dest));
-
+	goto discard;
+csum_error:
+	UDP6_INC_STATS_BH(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
 discard:
 	UDP6_INC_STATS_BH(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
 	kfree_skb(skb);