[PATCH net-next 04/10] net/tcp: Add tcp-md5 and tcp-ao tracepoints

From: Dmitry Safonov
Date: Sat Feb 24 2024 - 04:06:19 EST

Instead of forcing userspace to parse dmesg (that's what currently is
happening, at least in codebase of my current company), provide a better
way, that can be enabled/disabled in runtime.

Currently, there are already tcp events, add hashing related ones there,
too. Rasdaemon currently exercises net_dev_xmit_timeout,
devlink_health_report, but it'll be trivial to teach it to deal with
failed hashes. Otherwise, BGP may trace/log them itself. Especially
exciting for possible investigations is key rotation (RNext_key
requests).

Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
include/trace/events/tcp.h | 317 +++++++++++++++++++++++++++++++++++++++++++++
net/ipv4/tcp.c | 7 +
net/ipv4/tcp_ao.c | 13 ++
net/ipv4/tcp_input.c | 8 +-
net/ipv4/tcp_output.c | 2 +
5 files changed, 345 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 7b1ddffa3dfc..5065000aad93 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -419,6 +419,323 @@ TRACE_EVENT(tcp_cong_state_set,
__entry->cong_state)
);

+DECLARE_EVENT_CLASS(tcp_hash_event,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+
+ TP_ARGS(sk, skb),
+
+ TP_STRUCT__entry(
+ __field(__u64, net_cookie)
+ __field(const void *, skbaddr)
+ __field(const void *, skaddr)
+ __field(int, state)
+
+ /* sockaddr_in6 is always bigger than sockaddr_in */
+ __array(__u8, saddr, sizeof(struct sockaddr_in6))
+ __array(__u8, daddr, sizeof(struct sockaddr_in6))
+ __field(int, l3index)
+
+ __field(__u16, sport)
+ __field(__u16, dport)
+ __field(__u16, family)
+
+ __field(bool, fin)
+ __field(bool, syn)
+ __field(bool, rst)
+ __field(bool, psh)
+ __field(bool, ack)
+ ),
+
+ TP_fast_assign(
+ const struct tcphdr *th = (const struct tcphdr *)skb->data;
+
+ __entry->net_cookie = sock_net(sk)->net_cookie;
+ __entry->skbaddr = skb;
+ __entry->skaddr = sk;
+ __entry->state = sk->sk_state;
+
+ memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+ memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+ TP_STORE_ADDR_PORTS_SKB(__entry, skb);
+ __entry->l3index = inet_sdif(skb) ? inet_iif(skb) : 0;
+
+ /* For filtering use */
+ __entry->sport = ntohs(th->source);
+ __entry->dport = ntohs(th->dest);
+ __entry->family = sk->sk_family;
+
+ __entry->fin = th->fin;
+ __entry->syn = th->syn;
+ __entry->rst = th->rst;
+ __entry->psh = th->psh;
+ __entry->ack = th->ack;
+ ),
+
+ TP_printk("net=%llu state=%s family=%s src=%pISpc dest=%pISpc L3index=%d [%c%c%c%c%c]",
+ __entry->net_cookie,
+ show_tcp_state_name(__entry->state),
+ show_family_name(__entry->family),
+ __entry->saddr, __entry->daddr,
+ __entry->l3index,
+ __entry->fin ? 'F' : ' ',
+ __entry->syn ? 'S' : ' ',
+ __entry->rst ? 'R' : ' ',
+ __entry->psh ? 'P' : ' ',
+ __entry->ack ? '.' : ' ')
+);
+
+DEFINE_EVENT(tcp_hash_event, tcp_hash_bad_header,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+ TP_ARGS(sk, skb)
+);
+
+DEFINE_EVENT(tcp_hash_event, tcp_hash_md5_required,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+ TP_ARGS(sk, skb)
+);
+
+DEFINE_EVENT(tcp_hash_event, tcp_hash_md5_unexpected,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+ TP_ARGS(sk, skb)
+);
+
+DEFINE_EVENT(tcp_hash_event, tcp_hash_md5_mismatch,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+ TP_ARGS(sk, skb)
+);
+
+DEFINE_EVENT(tcp_hash_event, tcp_hash_ao_required,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+ TP_ARGS(sk, skb)
+);
+
+DECLARE_EVENT_CLASS(tcp_ao_event,
+
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+
+ TP_ARGS(sk, skb, keyid, rnext, maclen),
+
+ TP_STRUCT__entry(
+ __field(__u64, net_cookie)
+ __field(const void *, skbaddr)
+ __field(const void *, skaddr)
+ __field(int, state)
+
+ /* sockaddr_in6 is always bigger than sockaddr_in */
+ __array(__u8, saddr, sizeof(struct sockaddr_in6))
+ __array(__u8, daddr, sizeof(struct sockaddr_in6))
+ __field(int, l3index)
+
+ __field(__u16, sport)
+ __field(__u16, dport)
+ __field(__u16, family)
+
+ __field(bool, fin)
+ __field(bool, syn)
+ __field(bool, rst)
+ __field(bool, psh)
+ __field(bool, ack)
+
+ __field(__u8, keyid)
+ __field(__u8, rnext)
+ __field(__u8, maclen)
+ ),
+
+ TP_fast_assign(
+ const struct tcphdr *th = (const struct tcphdr *)skb->data;
+
+ __entry->net_cookie = sock_net(sk)->net_cookie;
+ __entry->skbaddr = skb;
+ __entry->skaddr = sk;
+ __entry->state = sk->sk_state;
+
+ memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+ memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+ TP_STORE_ADDR_PORTS_SKB(__entry, skb);
+ __entry->l3index = inet_sdif(skb) ? inet_iif(skb) : 0;
+
+ /* For filtering use */
+ __entry->sport = ntohs(th->source);
+ __entry->dport = ntohs(th->dest);
+ __entry->family = sk->sk_family;
+
+ __entry->fin = th->fin;
+ __entry->syn = th->syn;
+ __entry->rst = th->rst;
+ __entry->psh = th->psh;
+ __entry->ack = th->ack;
+
+ __entry->keyid = keyid;
+ __entry->rnext = rnext;
+ __entry->maclen = maclen;
+ ),
+
+ TP_printk("net=%llu state=%s family=%s src=%pISpc dest=%pISpc L3index=%d [%c%c%c%c%c] keyid=%u rnext=%u maclen=%u",
+ __entry->net_cookie,
+ show_tcp_state_name(__entry->state),
+ show_family_name(__entry->family),
+ __entry->saddr, __entry->daddr,
+ __entry->l3index,
+ __entry->fin ? 'F' : ' ',
+ __entry->syn ? 'S' : ' ',
+ __entry->rst ? 'R' : ' ',
+ __entry->psh ? 'P' : ' ',
+ __entry->ack ? '.' : ' ',
+ __entry->keyid, __entry->rnext, __entry->maclen)
+);
+
+DEFINE_EVENT(tcp_ao_event, tcp_ao_handshake_failure,
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+ TP_ARGS(sk, skb, keyid, rnext, maclen)
+);
+
+DEFINE_EVENT(tcp_ao_event, tcp_ao_wrong_maclen,
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+ TP_ARGS(sk, skb, keyid, rnext, maclen)
+);
+
+DEFINE_EVENT(tcp_ao_event, tcp_ao_mismatch,
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+ TP_ARGS(sk, skb, keyid, rnext, maclen)
+);
+
+DEFINE_EVENT(tcp_ao_event, tcp_ao_key_not_found,
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+ TP_ARGS(sk, skb, keyid, rnext, maclen)
+);
+
+DEFINE_EVENT(tcp_ao_event, tcp_ao_rnext_request,
+ TP_PROTO(const struct sock *sk, const struct sk_buff *skb,
+ const __u8 keyid, const __u8 rnext, const __u8 maclen),
+ TP_ARGS(sk, skb, keyid, rnext, maclen)
+);
+
+DECLARE_EVENT_CLASS(tcp_ao_event_sk,
+
+ TP_PROTO(const struct sock *sk, const __u8 keyid, const __u8 rnext),
+
+ TP_ARGS(sk, keyid, rnext),
+
+ TP_STRUCT__entry(
+ __field(__u64, net_cookie)
+ __field(const void *, skaddr)
+ __field(int, state)
+
+ /* sockaddr_in6 is always bigger than sockaddr_in */
+ __array(__u8, saddr, sizeof(struct sockaddr_in6))
+ __array(__u8, daddr, sizeof(struct sockaddr_in6))
+
+ __field(__u16, sport)
+ __field(__u16, dport)
+ __field(__u16, family)
+
+ __field(__u8, keyid)
+ __field(__u8, rnext)
+ ),
+
+ TP_fast_assign(
+ const struct inet_sock *inet = inet_sk(sk);
+
+ __entry->net_cookie = sock_net(sk)->net_cookie;
+ __entry->skaddr = sk;
+ __entry->state = sk->sk_state;
+
+ memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+ memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+ TP_STORE_ADDR_PORTS(__entry, inet, sk);
+
+ /* For filtering use */
+ __entry->sport = ntohs(inet->inet_sport);
+ __entry->dport = ntohs(inet->inet_dport);
+ __entry->family = sk->sk_family;
+
+ __entry->keyid = keyid;
+ __entry->rnext = rnext;
+ ),
+
+ TP_printk("net=%llu state=%s family=%s src=%pISpc dest=%pISpc keyid=%u rnext=%u",
+ __entry->net_cookie,
+ show_tcp_state_name(__entry->state),
+ show_family_name(__entry->family),
+ __entry->saddr, __entry->daddr,
+ __entry->keyid, __entry->rnext)
+);
+
+DEFINE_EVENT(tcp_ao_event_sk, tcp_ao_synack_no_key,
+ TP_PROTO(const struct sock *sk, const __u8 keyid, const __u8 rnext),
+ TP_ARGS(sk, keyid, rnext)
+);
+
+DECLARE_EVENT_CLASS(tcp_ao_event_sne,
+
+ TP_PROTO(const struct sock *sk, __u32 new_sne),
+
+ TP_ARGS(sk, new_sne),
+
+ TP_STRUCT__entry(
+ __field(__u64, net_cookie)
+ __field(const void *, skaddr)
+ __field(int, state)
+
+ /* sockaddr_in6 is always bigger than sockaddr_in */
+ __array(__u8, saddr, sizeof(struct sockaddr_in6))
+ __array(__u8, daddr, sizeof(struct sockaddr_in6))
+
+ __field(__u16, sport)
+ __field(__u16, dport)
+ __field(__u16, family)
+
+ __field(__u32, new_sne)
+ ),
+
+ TP_fast_assign(
+ const struct inet_sock *inet = inet_sk(sk);
+
+ __entry->net_cookie = sock_net(sk)->net_cookie;
+ __entry->skaddr = sk;
+ __entry->state = sk->sk_state;
+
+ memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
+ memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
+ TP_STORE_ADDR_PORTS(__entry, inet, sk);
+
+ /* For filtering use */
+ __entry->sport = ntohs(inet->inet_sport);
+ __entry->dport = ntohs(inet->inet_dport);
+ __entry->family = sk->sk_family;
+
+ __entry->new_sne = new_sne;
+ ),
+
+ TP_printk("net=%llu state=%s family=%s src=%pISpc dest=%pISpc sne=%u",
+ __entry->net_cookie,
+ show_tcp_state_name(__entry->state),
+ show_family_name(__entry->family),
+ __entry->saddr, __entry->daddr,
+ __entry->new_sne)
+);
+
+DEFINE_EVENT(tcp_ao_event_sne, tcp_ao_snd_sne_update,
+ TP_PROTO(const struct sock *sk, __u32 new_sne),
+ TP_ARGS(sk, new_sne)
+);
+
+DEFINE_EVENT(tcp_ao_event_sne, tcp_ao_rcv_sne_update,
+ TP_PROTO(const struct sock *sk, __u32 new_sne),
+ TP_ARGS(sk, new_sne)
+);
+
#endif /* _TRACE_TCP_H */

/* This part must be outside protection */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5fd61ae6bcc9..81f22d6afe4a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -279,6 +279,7 @@
#include <linux/uaccess.h>
#include <asm/ioctls.h>
#include <net/busy_poll.h>
+#include <trace/events/tcp.h>

/* Track pending CMSGs. */
enum {
@@ -4448,6 +4449,7 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
if (!key && hash_location) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
tcp_hash_fail("Unexpected MD5 Hash found", family, skb, "");
+ trace_tcp_hash_md5_unexpected(sk, skb);
return SKB_DROP_REASON_TCP_MD5UNEXPECTED;
}

@@ -4477,6 +4479,7 @@ tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
l3index);
}
}
+ trace_tcp_hash_md5_mismatch(sk, skb);
return SKB_DROP_REASON_TCP_MD5FAILURE;
}
return SKB_NOT_DROPPED_YET;
@@ -4501,6 +4504,7 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
if (tcp_parse_auth_options(th, &md5_location, &aoh)) {
tcp_hash_fail("TCP segment has incorrect auth options set",
family, skb, "");
+ trace_tcp_hash_bad_header(sk, skb);
return SKB_DROP_REASON_TCP_AUTH_HDR;
}

@@ -4520,6 +4524,7 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
tcp_hash_fail("TCP connection can't start/end using TCP-AO",
family, skb, "%s",
!aoh ? "missing AO" : "AO signed");
+ trace_tcp_ao_handshake_failure(sk, skb, keyid, rnext, maclen);
return SKB_DROP_REASON_TCP_AOFAILURE;
}
}
@@ -4539,12 +4544,14 @@ tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
if (tcp_ao_required(sk, saddr, family, l3index, true)) {
tcp_hash_fail("AO hash is required, but not found",
family, skb, "L3 index %d", l3index);
+ trace_tcp_hash_ao_required(sk, skb);
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);
tcp_hash_fail("MD5 Hash not found",
family, skb, "L3 index %d", l3index);
+ trace_tcp_hash_md5_required(sk, skb);
return SKB_DROP_REASON_TCP_MD5NOTFOUND;
}
return SKB_NOT_DROPPED_YET;
diff --git a/net/ipv4/tcp_ao.c b/net/ipv4/tcp_ao.c
index 8726aa58e8b6..416cdeaccd07 100644
--- a/net/ipv4/tcp_ao.c
+++ b/net/ipv4/tcp_ao.c
@@ -16,6 +16,7 @@
#include <net/tcp.h>
#include <net/ipv6.h>
#include <net/icmp.h>
+#include <trace/events/tcp.h>

DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_ao_needed, HZ);

@@ -895,6 +896,8 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
tcp_hash_fail("AO hash wrong length", family, skb,
"%u != %d L3index: %d", maclen,
tcp_ao_maclen(key), l3index);
+ trace_tcp_ao_wrong_maclen(sk, skb, aoh->keyid,
+ aoh->rnext_keyid, maclen);
return SKB_DROP_REASON_TCP_AOFAILURE;
}

@@ -911,6 +914,8 @@ tcp_ao_verify_hash(const struct sock *sk, const struct sk_buff *skb,
atomic64_inc(&key->pkt_bad);
tcp_hash_fail("AO hash mismatch", family, skb,
"L3index: %d", l3index);
+ trace_tcp_ao_mismatch(sk, skb, aoh->keyid,
+ aoh->rnext_keyid, maclen);
kfree(hash_buf);
return SKB_DROP_REASON_TCP_AOFAILURE;
}
@@ -927,6 +932,7 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
int l3index, const struct tcp_ao_hdr *aoh)
{
const struct tcphdr *th = tcp_hdr(skb);
+ u8 maclen = tcp_ao_hdr_maclen(aoh);
u8 *phash = (u8 *)(aoh + 1); /* hash goes just after the header */
struct tcp_ao_info *info;
enum skb_drop_reason ret;
@@ -940,6 +946,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOKEYNOTFOUND);
tcp_hash_fail("AO key not found", family, skb,
"keyid: %u L3index: %d", aoh->keyid, l3index);
+ trace_tcp_ao_key_not_found(sk, skb, aoh->keyid,
+ aoh->rnext_keyid, maclen);
return SKB_DROP_REASON_TCP_AOUNEXPECTED;
}

@@ -979,6 +987,9 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
current_key = READ_ONCE(info->current_key);
/* Key rotation: the peer asks us to use new key (RNext) */
if (unlikely(aoh->rnext_keyid != current_key->sndid)) {
+ trace_tcp_ao_rnext_request(sk, skb, current_key->sndid,
+ aoh->rnext_keyid,
+ tcp_ao_hdr_maclen(aoh));
/* If the key is not found we do nothing. */
key = tcp_ao_established_key(info, aoh->rnext_keyid, -1);
if (key)
@@ -1043,6 +1054,8 @@ tcp_inbound_ao_hash(struct sock *sk, const struct sk_buff *skb,
atomic64_inc(&info->counters.key_not_found);
tcp_hash_fail("Requested by the peer AO key id not found",
family, skb, "L3index: %d", l3index);
+ trace_tcp_ao_key_not_found(sk, skb, aoh->keyid,
+ aoh->rnext_keyid, maclen);
return SKB_DROP_REASON_TCP_AOKEYNOTFOUND;
}

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 74c03f0a6c0c..11f4da3aa827 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3575,8 +3575,10 @@ static void tcp_snd_sne_update(struct tcp_sock *tp, u32 ack)

ao = rcu_dereference_protected(tp->ao_info,
lockdep_sock_is_held((struct sock *)tp));
- if (ao && ack < tp->snd_una)
+ if (ao && ack < tp->snd_una) {
ao->snd_sne++;
+ trace_tcp_ao_snd_sne_update((struct sock *)tp, ao->snd_sne);
+ }
#endif
}

@@ -3601,8 +3603,10 @@ static void tcp_rcv_sne_update(struct tcp_sock *tp, u32 seq)

ao = rcu_dereference_protected(tp->ao_info,
lockdep_sock_is_held((struct sock *)tp));
- if (ao && seq < tp->rcv_nxt)
+ if (ao && seq < tp->rcv_nxt) {
ao->rcv_sne++;
+ trace_tcp_ao_rcv_sne_update((struct sock *)tp, ao->rcv_sne);
+ }
#endif
}

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e3167ad96567..dcdaf3229de9 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3727,6 +3727,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
#ifdef CONFIG_TCP_AO
struct tcp_ao_key *ao_key = NULL;
u8 keyid = tcp_rsk(req)->ao_keyid;
+ u8 rnext = tcp_rsk(req)->ao_rcv_next;

ao_key = tcp_sk(sk)->af_specific->ao_lookup(sk, req_to_sk(req),
keyid, -1);
@@ -3736,6 +3737,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
* ao_keyid (RFC5925 RNextKeyID), so let's keep it simple here.
*/
if (unlikely(!ao_key)) {
+ trace_tcp_ao_synack_no_key(sk, keyid, rnext);
rcu_read_unlock();
kfree_skb(skb);
net_warn_ratelimited("TCP-AO: the keyid %u from SYN packet is not present - not sending SYNACK\n",

--
2.43.0