From 81678c6961f1a70087158c30d6c9de47f1f2cfc8 Mon Sep 17 00:00:00 2001 From: Jason Xing Date: Mon, 1 Apr 2024 15:36:05 +0800 Subject: [PATCH] trace: tcp: fully support trace_tcp_send_reset Prior to this patch, what we can see by enabling trace_tcp_send is only happening under two circumstances: 1) active rst mode 2) non-active rst mode and based on the full socket That means the inconsistency occurs if we use tcpdump and trace simultaneously to see how rst happens. It's necessary that we should take into other cases into considerations, say: 1) time-wait socket 2) no socket ... By parsing the incoming skb and reversing its 4-tuple can we know the exact 'flow' which might not exist. Samples after applied this patch: 1. tcp_send_reset: skbaddr=XXX skaddr=XXX src=ip:port dest=ip:port state=TCP_ESTABLISHED 2. tcp_send_reset: skbaddr=000...000 skaddr=XXX src=ip:port dest=ip:port state=UNKNOWN Note: 1) UNKNOWN means we cannot extract the right information from skb. 2) skbaddr/skaddr could be 0 Signed-off-by: Jason Xing Signed-off-by: NipaLocal --- include/trace/events/tcp.h | 40 ++++++++++++++++++++++++++++++++++++-- net/ipv4/tcp_ipv4.c | 7 +++---- net/ipv6/tcp_ipv6.c | 3 ++- 3 files changed, 43 insertions(+), 7 deletions(-) diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h index cf14b6fcbeed7f..5c04a61a11c2c8 100644 --- a/include/trace/events/tcp.h +++ b/include/trace/events/tcp.h @@ -78,11 +78,47 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb, * skb of trace_tcp_send_reset is the skb that caused RST. In case of * active reset, skb should be NULL */ -DEFINE_EVENT(tcp_event_sk_skb, tcp_send_reset, +TRACE_EVENT(tcp_send_reset, TP_PROTO(const struct sock *sk, const struct sk_buff *skb), - TP_ARGS(sk, skb) + TP_ARGS(sk, skb), + + TP_STRUCT__entry( + __field(const void *, skbaddr) + __field(const void *, skaddr) + __field(int, state) + __array(__u8, saddr, sizeof(struct sockaddr_in6)) + __array(__u8, daddr, sizeof(struct sockaddr_in6)) + ), + + TP_fast_assign( + __entry->skbaddr = skb; + __entry->skaddr = sk; + /* Zero means unknown state. */ + __entry->state = sk ? sk->sk_state : 0; + + memset(__entry->saddr, 0, sizeof(struct sockaddr_in6)); + memset(__entry->daddr, 0, sizeof(struct sockaddr_in6)); + + if (sk && sk_fullsock(sk)) { + const struct inet_sock *inet = inet_sk(sk); + + TP_STORE_ADDR_PORTS(__entry, inet, sk); + } else if (skb) { + const struct tcphdr *th = (const struct tcphdr *)skb->data; + /* + * We should reverse the 4-tuple of skb, so later + * it can print the right flow direction of rst. + */ + TP_STORE_ADDR_PORTS_SKB(skb, th, entry->daddr, entry->saddr); + } + ), + + TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s", + __entry->skbaddr, __entry->skaddr, + __entry->saddr, __entry->daddr, + __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN") ); /* diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 1e0a9762f92e60..56b75efcfd12bf 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -866,11 +866,10 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) * routing might fail in this case. No choice here, if we choose to force * input interface, we will misroute in case of asymmetric route. */ - if (sk) { + if (sk) arg.bound_dev_if = sk->sk_bound_dev_if; - if (sk_fullsock(sk)) - trace_tcp_send_reset(sk, skb); - } + + trace_tcp_send_reset(sk, skb); BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) != offsetof(struct inet_timewait_sock, tw_bound_dev_if)); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 5ae74f661d25f9..cffebaec66f1ab 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1113,7 +1113,6 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb) if (sk) { oif = sk->sk_bound_dev_if; if (sk_fullsock(sk)) { - trace_tcp_send_reset(sk, skb); if (inet6_test_bit(REPFLOW, sk)) label = ip6_flowlabel(ipv6h); priority = READ_ONCE(sk->sk_priority); @@ -1129,6 +1128,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb) label = ip6_flowlabel(ipv6h); } + trace_tcp_send_reset(sk, skb); + tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1, ipv6_get_dsfield(ipv6h), label, priority, txhash, &key);