tcp: md5: add LINUX_MIB_TCPMD5FAILURE counter

Adds SNMP counter for drops caused by MD5 mismatches.

The current syslog might help, but a counter is more precise and helps
monitoring.

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

3 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 9f665b63a927..1ed015e4bc79 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -257,6 +257,7 @@ static const struct snmp_mib snmp4_net_list[] = {
         SNMP_MIB_ITEM("TCPSpuriousRTOs", LINUX_MIB_TCPSPURIOUSRTOS),
         SNMP_MIB_ITEM("TCPMD5NotFound", LINUX_MIB_TCPMD5NOTFOUND),
         SNMP_MIB_ITEM("TCPMD5Unexpected", LINUX_MIB_TCPMD5UNEXPECTED),
+        SNMP_MIB_ITEM("TCPMD5Failure", LINUX_MIB_TCPMD5FAILURE),
         SNMP_MIB_ITEM("TCPSackShifted", LINUX_MIB_SACKSHIFTED),
         SNMP_MIB_ITEM("TCPSackMerged", LINUX_MIB_SACKMERGED),
         SNMP_MIB_ITEM("TCPSackShiftFallback", LINUX_MIB_SACKSHIFTFALLBACK),
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 436d978c6c39..ad41e8ecf796 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1169,6 +1169,7 @@ static bool tcp_v4_inbound_md5_hash(const struct sock *sk,
                                       NULL, skb);
 
         if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
                 net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
                                      &iph->saddr, ntohs(th->source),
                                      &iph->daddr, ntohs(th->dest),
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index ac0ed7bda406..e4f55683af31 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -671,6 +671,7 @@ static bool tcp_v6_inbound_md5_hash(const struct sock *sk,
                                       NULL, skb);
 
         if (genhash || memcmp(hash_location, newhash, 16) != 0) {
+                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5FAILURE);
                 net_info_ratelimited("MD5 Hash %s for [%pI6c]:%u->[%pI6c]:%u\n",
                                      genhash ? "failed" : "mismatch",
                                      &ip6h->saddr, ntohs(th->source),