Subject: [PATCH v13 net-next 13/23] net/tcp: Add TCP-AO segments counters

From: Dmitry Safonov <[email-masked]>
Date: Wed, 4 Oct 2023 23:36:17 +0100

Introduce segment counters that are useful for troubleshooting/debugging
as well as for writing tests.
Now there are global snmp counters as well as per-socket and per-key.

Co-developed-by: Francesco Ruggeri <[email-masked]>
Signed-off-by: Francesco Ruggeri <[email-masked]>
Co-developed-by: Salam Noureddine <[email-masked]>
Signed-off-by: Salam Noureddine <[email-masked]>
Signed-off-by: Dmitry Safonov <[email-masked]>
Acked-by: David Ahern <[email-masked]>
---
 include/net/dropreason-core.h | 15 +++++++++++----
 include/net/tcp.h             | 15 +++++++++++----
 include/net/tcp_ao.h          | 10 ++++++++++
 include/uapi/linux/snmp.h     |  4 ++++
 include/uapi/linux/tcp.h      |  8 +++++++-
 net/ipv4/proc.c               |  4 ++++
 net/ipv4/tcp_ao.c             | 30 +++++++++++++++++++++++++++---
 net/ipv4/tcp_ipv4.c           |  2 +-
 net/ipv6/tcp_ipv6.c           |  4 ++--
 9 files changed, 77 insertions(+), 15 deletions(-)

diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index a01e1860fe25..efb6ea5ffb1e 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -167,17 +167,24 @@ enum skb_drop_reason {
 	 */
 	SKB_DROP_REASON_TCP_MD5FAILURE,
 	/**
-	 * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected
+	 * @SKB_DROP_REASON_TCP_AONOTFOUND: no TCP-AO hash and one was expected,
+	 * corresponding to LINUX_MIB_TCPAOREQUIRED
 	 */
 	SKB_DROP_REASON_TCP_AONOTFOUND,
 	/**
 	 * @SKB_DROP_REASON_TCP_AOUNEXPECTED: TCP-AO hash is present and it
-	 * was not expected.
+	 * was not expected, corresponding to LINUX_MIB_TCPAOKEYNOTFOUND
 	 */
 	SKB_DROP_REASON_TCP_AOUNEXPECTED,
-	/** @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown */
+	/**
+	 * @SKB_DROP_REASON_TCP_AOKEYNOTFOUND: TCP-AO key is unknown,
+	 * corresponding to LINUX_MIB_TCPAOKEYNOTFOUND
+	 */
 	SKB_DROP_REASON_TCP_AOKEYNOTFOUND,
-	/** @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong */
+	/**
+	 * @SKB_DROP_REASON_TCP_AOFAILURE: TCP-AO hash is wrong,
+	 * corresponding to LINUX_MIB_TCPAOBAD
+	 */
 	SKB_DROP_REASON_TCP_AOFAILURE,
 	/**
 	 * @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog (
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2433687c462b..ae83a4101a7c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2672,7 +2672,7 @@ static inline int tcp_parse_auth_options(const struct tcphdr *th,
 }
 
 static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
-				   int family)
+				   int family, bool stat_inc)
 {
 #ifdef CONFIG_TCP_AO
 	struct tcp_ao_info *ao_info;
@@ -2684,8 +2684,13 @@ static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
 		return false;
 
 	ao_key = tcp_ao_do_lookup(sk, saddr, family, -1, -1);
-	if (ao_info->ao_required || ao_key)
+	if (ao_info->ao_required || ao_key) {
+		if (stat_inc) {
+			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED);
+			atomic64_inc(&ao_info->counters.ao_required);
+		}
 		return true;
+	}
 #endif
 	return false;
 }
@@ -2707,8 +2712,10 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
 		return SKB_DROP_REASON_TCP_AUTH_HDR;
 
 	if (req) {
-		if (tcp_rsk_used_ao(req) != !!aoh)
+		if (tcp_rsk_used_ao(req) != !!aoh) {
+			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
 			return SKB_DROP_REASON_TCP_AOFAILURE;
+		}
 	}
 
 	/* sdif set, means packet ingressed via a device
@@ -2723,7 +2730,7 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
 		 * the last key is impossible to remove, so there's
 		 * always at least one current_key.
 		 */
-		if (tcp_ao_required(sk, saddr, family))
+		if (tcp_ao_required(sk, saddr, family, true))
 			return SKB_DROP_REASON_TCP_AONOTFOUND;
 		if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
 			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
diff --git a/include/net/tcp_ao.h b/include/net/tcp_ao.h
index 6e62235c7cae..b34b9a37c81b 100644
--- a/include/net/tcp_ao.h
+++ b/include/net/tcp_ao.h
@@ -19,6 +19,13 @@ struct tcp_ao_hdr {
 	u8	rnext_keyid;
 };
 
+struct tcp_ao_counters {
+	atomic64_t	pkt_good;
+	atomic64_t	pkt_bad;
+	atomic64_t	key_not_found;
+	atomic64_t	ao_required;
+};
+
 struct tcp_ao_key {
 	struct hlist_node	node;
 	union tcp_ao_addr	addr;
@@ -33,6 +40,8 @@ struct tcp_ao_key {
 	u8			rcvid;
 	u8			maclen;
 	struct rcu_head		rcu;
+	atomic64_t		pkt_good;
+	atomic64_t		pkt_bad;
 	u8			traffic_keys[];
 };
 
@@ -81,6 +90,7 @@ struct tcp_ao_info {
 	 */
 	struct tcp_ao_key	*current_key;
 	struct tcp_ao_key	*rnext_key;
+	struct tcp_ao_counters	counters;
 	u32			ao_required	:1,
 				__unused	:31;
 	__be32			lisn;
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 26f33a4c253d..06ddf4cd295c 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -296,6 +296,10 @@ enum
 	LINUX_MIB_TCPMIGRATEREQSUCCESS,		/* TCPMigrateReqSuccess */
 	LINUX_MIB_TCPMIGRATEREQFAILURE,		/* TCPMigrateReqFailure */
 	LINUX_MIB_TCPPLBREHASH,			/* TCPPLBRehash */
+	LINUX_MIB_TCPAOREQUIRED,		/* TCPAORequired */
+	LINUX_MIB_TCPAOBAD,			/* TCPAOBad */
+	LINUX_MIB_TCPAOKEYNOTFOUND,		/* TCPAOKeyNotFound */
+	LINUX_MIB_TCPAOGOOD,			/* TCPAOGood */
 	__LINUX_MIB_MAX
 };
 
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8285300f95c9..62543f7c5523 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -403,9 +403,15 @@ struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO) */
 	__u32   set_current	:1,	/* corresponding ::current_key */
 		set_rnext	:1,	/* corresponding ::rnext */
 		ao_required	:1,	/* don't accept non-AO connects */
-		reserved	:29;	/* must be 0 */
+		set_counters	:1,	/* set/clear ::pkt_* counters */
+		reserved	:28;	/* must be 0 */
+	__u16	reserved2;		/* padding, must be 0 */
 	__u8	current_key;		/* KeyID to set as Current_key */
 	__u8	rnext;			/* KeyID to set as Rnext_key */
+	__u64	pkt_good;		/* verified segments */
+	__u64	pkt_bad;		/* failed verification */
+	__u64	pkt_key_not_found;	/* could not find a key to verify */
+	__u64	pkt_ao_required;	/* segments missing TCP-AO sign */
 } __attribute__((aligned(8)));
 
 /* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index eaf1d3113b62..3f643cd29cfe 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -298,6 +298,10 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS),
 	SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE),
 	SNMP_MIB_ITEM("TCPPLBRehash", LINUX_MIB_TCPPLBREHASH),
+	SNMP_MIB_ITEM("TCPAORequired", LINUX_MIB_TCPAOREQUIRED),
+	SNMP_MIB_ITEM("TCPAOBad", LINUX_MIB_TCPAOBAD),
+	SNMP_MIB_ITEM("TCPAOKeyNotFound", LINUX_MIB_TCPAOKEYNOTFOUND),
+	SNMP_MIB_ITEM("TCPAOGood", LINUX_MIB_TCPAOGOOD),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 4813b9283c55..f7ee2aecf8fc 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -182,6 +182,8 @@ static struct tcp_ao_key *tcp_ao_copy_key(struct sock *sk,
 	*new_key = *key;
 	INIT_HLIST_NODE(&new_key->node);
 	tcp_sigpool_get(new_key->tcp_sigpool_id);
+	atomic64_set(&new_key->pkt_good, 0);
+	atomic64_set(&new_key->pkt_bad, 0);
 
 	return new_key;
 }
@@ -771,8 +773,12 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
 	const struct tcphdr *th = tcp_hdr(skb);
 	void *hash_buf = NULL;
 
-	if (maclen != tcp_ao_maclen(key))
+	if (maclen != tcp_ao_maclen(key)) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
+		atomic64_inc(&info->counters.pkt_bad);
+		atomic64_inc(&key->pkt_bad);
 		return SKB_DROP_REASON_TCP_AOFAILURE;
+	}
 
 	hash_buf = kmalloc(tcp_ao_digest_size(key), GFP_ATOMIC);
 	if (!hash_buf)
@@ -782,9 +788,15 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
 	tcp_ao_hash_skb(family, hash_buf, key, sk, skb, traffic_key,
 			(phash - (u8 *)th), sne);
 	if (memcmp(phash, hash_buf, maclen)) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
+		atomic64_inc(&info->counters.pkt_bad);
+		atomic64_inc(&key->pkt_bad);
 		kfree(hash_buf);
 		return SKB_DROP_REASON_TCP_AOFAILURE;
 	}
+	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOGOOD);
+	atomic64_inc(&info->counters.pkt_good);
+	atomic64_inc(&key->pkt_good);
 	kfree(hash_buf);
 	return SKB_NOT_DROPPED_YET;
 }
@@ -804,8 +816,10 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
 	u32 sne = 0;
 
 	info = rcu_dereference(tcp_sk(sk)->ao_info);
-	if (!info)
+	if (!info) {
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);
 		return SKB_DROP_REASON_TCP_AOUNEXPECTED;
+	}
 
 	if (unlikely(th->syn)) {
 		sisn = th->seq;
@@ -900,6 +914,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
 	return ret;
 
 key_not_found:
+	NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);
+	atomic64_inc(&info->counters.key_not_found);
 	return SKB_DROP_REASON_TCP_AOKEYNOTFOUND;
 }
 
@@ -1480,6 +1496,8 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family,
 	key->keyflags	= cmd.keyflags;
 	key->sndid	= cmd.sndid;
 	key->rcvid	= cmd.rcvid;
+	atomic64_set(&key->pkt_good, 0);
+	atomic64_set(&key->pkt_bad, 0);
 
 	ret = tcp_ao_parse_crypto(&cmd, key);
 	if (ret < 0)
@@ -1696,7 +1714,7 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
 			return -EINVAL;
 	}
 
-	if (cmd.reserved != 0)
+	if (cmd.reserved != 0 || cmd.reserved2 != 0)
 		return -EINVAL;
 
 	ao_info = setsockopt_ao_info(sk);
@@ -1731,6 +1749,12 @@ static int tcp_ao_info_cmd(struct sock *sk, unsigned short int family,
 			goto out;
 		}
 	}
+	if (cmd.set_counters) {
+		atomic64_set(&ao_info->counters.pkt_good, cmd.pkt_good);
+		atomic64_set(&ao_info->counters.pkt_bad, cmd.pkt_bad);
+		atomic64_set(&ao_info->counters.key_not_found, cmd.pkt_key_not_found);
+		atomic64_set(&ao_info->counters.ao_required, cmd.pkt_ao_required);
+	}
 
 	ao_info->ao_required = cmd.ao_required;
 	if (new_current)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1b1ad6da5929..1e714b26d9ce 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1530,7 +1530,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
 	/* Don't allow keys for peers that have a matching TCP-AO key.
 	 * See the comment in tcp_ao_add_cmd()
 	 */
-	if (tcp_ao_required(sk, addr, AF_INET))
+	if (tcp_ao_required(sk, addr, AF_INET, false))
 		return -EKEYREJECTED;
 
 	return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 412e75788247..05f3421f26ea 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -660,7 +660,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 		/* Don't allow keys for peers that have a matching TCP-AO key.
 		 * See the comment in tcp_ao_add_cmd()
 		 */
-		if (tcp_ao_required(sk, addr, AF_INET))
+		if (tcp_ao_required(sk, addr, AF_INET, false))
 			return -EKEYREJECTED;
 		return tcp_md5_do_add(sk, addr,
 				      AF_INET, prefixlen, l3index, flags,
@@ -672,7 +672,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 	/* Don't allow keys for peers that have a matching TCP-AO key.
 	 * See the comment in tcp_ao_add_cmd()
 	 */
-	if (tcp_ao_required(sk, addr, AF_INET6))
+	if (tcp_ao_required(sk, addr, AF_INET6, false))
 		return -EKEYREJECTED;
 
 	return tcp_md5_do_add(sk, addr, AF_INET6, prefixlen, l3index, flags,
-- 
2.42.0