[RFCv2 7/9] tcp: authopt: Add snmp counters

[Leonard Crestez <cdleonard@gmail.com>]

Add LINUX_MIB_TCPAUTHOPTFAILURE and increment on failure. This can be
use by userspace to count the number of failed authentications.

All types of authentication failures are reported under a single
counter.

Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
---
 include/uapi/linux/snmp.h | 1 +
 net/ipv4/proc.c           | 1 +
 net/ipv4/tcp_authopt.c    | 3 +++
 3 files changed, 5 insertions(+)

diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 904909d020e2..1d96030889a1 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -290,10 +290,11 @@ enum
 	LINUX_MIB_TCPDUPLICATEDATAREHASH,	/* TCPDuplicateDataRehash */
 	LINUX_MIB_TCPDSACKRECVSEGS,		/* TCPDSACKRecvSegs */
 	LINUX_MIB_TCPDSACKIGNOREDDUBIOUS,	/* TCPDSACKIgnoredDubious */
 	LINUX_MIB_TCPMIGRATEREQSUCCESS,		/* TCPMigrateReqSuccess */
 	LINUX_MIB_TCPMIGRATEREQFAILURE,		/* TCPMigrateReqFailure */
+	LINUX_MIB_TCPAUTHOPTFAILURE,		/* TCPAuthOptFailure */
 	__LINUX_MIB_MAX
 };
 
 /* linux Xfrm mib definitions */
 enum
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index b0d3a09dc84e..61dd06f8389c 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -295,10 +295,11 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TcpDuplicateDataRehash", LINUX_MIB_TCPDUPLICATEDATAREHASH),
 	SNMP_MIB_ITEM("TCPDSACKRecvSegs", LINUX_MIB_TCPDSACKRECVSEGS),
 	SNMP_MIB_ITEM("TCPDSACKIgnoredDubious", LINUX_MIB_TCPDSACKIGNOREDDUBIOUS),
 	SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS),
 	SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE),
+	SNMP_MIB_ITEM("TCPAuthOptFailure", LINUX_MIB_TCPAUTHOPTFAILURE),
 	SNMP_MIB_SENTINEL
 };
 
 static void icmpmsg_put_line(struct seq_file *seq, unsigned long *vals,
 			     unsigned short *type, int count)
diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
index 40412d9ea04e..bee8873423e4 100644
--- a/net/ipv4/tcp_authopt.c
+++ b/net/ipv4/tcp_authopt.c
@@ -1043,10 +1043,11 @@ int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb, struct tcp
 
 	/* nothing found or expected */
 	if (!opt && !key)
 		return 0;
 	if (!opt && key) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTHOPTFAILURE);
 		net_info_ratelimited("TCP Authentication Missing\n");
 		return -EINVAL;
 	}
 	if (opt && !key) {
 		/* RFC5925 Section 7.3:
@@ -1054,10 +1055,11 @@ int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb, struct tcp
 		 * of segments with TCP-AO but that do not match an MKT. The initial
 		 * default of this configuration SHOULD be to silently accept such
 		 * connections.
 		 */
 		if (info->flags & TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED) {
+			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTHOPTFAILURE);
 			net_info_ratelimited("TCP Authentication Unexpected: Rejected\n");
 			return -EINVAL;
 		} else {
 			net_info_ratelimited("TCP Authentication Unexpected: Accepted\n");
 			goto accept;
@@ -1071,10 +1073,11 @@ int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb, struct tcp
 	err = __tcp_authopt_calc_mac(sk, skb, key, true, macbuf);
 	if (err)
 		return err;
 
 	if (memcmp(macbuf, opt->mac, key->maclen)) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTHOPTFAILURE);
 		net_info_ratelimited("TCP Authentication Failed\n");
 		return -EINVAL;
 	}
 
 accept:
-- 
2.25.1