[PATCH net-next v4 0/2] tcp: make trace of reset logic complete

linux-trace-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed

* [PATCH net-next v4 0/2] tcp: make trace of reset logic complete
@ 2024-04-01  7:36 Jason Xing
  2024-04-01  7:36 ` [PATCH net-next v4 1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters Jason Xing
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Jason Xing @ 2024-04-01  7:36 UTC (permalink / raw)
  To: edumazet, mhiramat, mathieu.desnoyers, rostedt, kuba, pabeni,
	davem
  Cc: netdev, linux-trace-kernel, kerneljasonxing, Jason Xing

From: Jason Xing <kernelxing@tencent.com>

Before this, we miss some cases where the TCP layer could send RST but
we cannot trace it. So I decided to complete it :)

v4
Link: https://lore.kernel.org/all/20240329034243.7929-1-kerneljasonxing@gmail.com/
1. rebased against latest net-next
2. remove {} and add skb test statement (Eric)
3. drop v3 patch [3/3] temporarily because 1) location is not that useful
since we can use perf or something else to trace, 2) Eric said we could
use drop_reason to show why we have to RST, which is good, but this seems
not work well for those ->send_reset() logic. I need more time to
investigate this part.

v3
1. fix a format problem in patch [3/3]

v2
1. fix spelling mistakes

Jason Xing (2):
  trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters
  trace: tcp: fully support trace_tcp_send_reset

 include/trace/events/net_probe_common.h | 20 ++++++------
 include/trace/events/tcp.h              | 42 +++++++++++++++++++++++--
 include/trace/events/udp.h              |  2 +-
 net/ipv4/tcp_ipv4.c                     |  7 ++---
 net/ipv6/tcp_ipv6.c                     |  3 +-
 5 files changed, 56 insertions(+), 18 deletions(-)

-- 
2.37.3

^ permalink raw reply	[flat|nested] 4+ messages in thread

* [PATCH net-next v4 1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters
  2024-04-01  7:36 [PATCH net-next v4 0/2] tcp: make trace of reset logic complete Jason Xing
@ 2024-04-01  7:36 ` Jason Xing
  2024-04-01  7:36 ` [PATCH net-next v4 2/2] trace: tcp: fully support trace_tcp_send_reset Jason Xing
  2024-04-04  2:30 ` [PATCH net-next v4 0/2] tcp: make trace of reset logic complete patchwork-bot+netdevbpf
  2 siblings, 0 replies; 4+ messages in thread
From: Jason Xing @ 2024-04-01  7:36 UTC (permalink / raw)
  To: edumazet, mhiramat, mathieu.desnoyers, rostedt, kuba, pabeni,
	davem
  Cc: netdev, linux-trace-kernel, kerneljasonxing, Jason Xing

From: Jason Xing <kernelxing@tencent.com>

Introducing entry_saddr and entry_daddr parameters in this macro
for later use can help us record the reverse 4-tuple by analyzing
the 4-tuple of the incoming skb when receiving.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 include/trace/events/net_probe_common.h | 20 +++++++++++---------
 include/trace/events/tcp.h              |  2 +-
 include/trace/events/udp.h              |  2 +-
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/include/trace/events/net_probe_common.h b/include/trace/events/net_probe_common.h
index 5e33f91bdea3..976a58364bff 100644
--- a/include/trace/events/net_probe_common.h
+++ b/include/trace/events/net_probe_common.h
@@ -70,14 +70,14 @@
 	TP_STORE_V4MAPPED(__entry, saddr, daddr)
 #endif
 
-#define TP_STORE_ADDR_PORTS_SKB_V4(__entry, skb, protoh)		\
+#define TP_STORE_ADDR_PORTS_SKB_V4(skb, protoh, entry_saddr, entry_daddr) \
 	do {								\
-		struct sockaddr_in *v4 = (void *)__entry->saddr;	\
+		struct sockaddr_in *v4 = (void *)entry_saddr;		\
 									\
 		v4->sin_family = AF_INET;				\
 		v4->sin_port = protoh->source;				\
 		v4->sin_addr.s_addr = ip_hdr(skb)->saddr;		\
-		v4 = (void *)__entry->daddr;				\
+		v4 = (void *)entry_daddr;				\
 		v4->sin_family = AF_INET;				\
 		v4->sin_port = protoh->dest;				\
 		v4->sin_addr.s_addr = ip_hdr(skb)->daddr;		\
@@ -85,28 +85,30 @@
 
 #if IS_ENABLED(CONFIG_IPV6)
 
-#define TP_STORE_ADDR_PORTS_SKB(__entry, skb, protoh)			\
+#define TP_STORE_ADDR_PORTS_SKB(skb, protoh, entry_saddr, entry_daddr)	\
 	do {								\
 		const struct iphdr *iph = ip_hdr(skb);			\
 									\
 		if (iph->version == 6) {				\
-			struct sockaddr_in6 *v6 = (void *)__entry->saddr; \
+			struct sockaddr_in6 *v6 = (void *)entry_saddr;	\
 									\
 			v6->sin6_family = AF_INET6;			\
 			v6->sin6_port = protoh->source;			\
 			v6->sin6_addr = ipv6_hdr(skb)->saddr;		\
-			v6 = (void *)__entry->daddr;			\
+			v6 = (void *)entry_daddr;			\
 			v6->sin6_family = AF_INET6;			\
 			v6->sin6_port = protoh->dest;			\
 			v6->sin6_addr = ipv6_hdr(skb)->daddr;		\
 		} else							\
-			TP_STORE_ADDR_PORTS_SKB_V4(__entry, skb, protoh); \
+			TP_STORE_ADDR_PORTS_SKB_V4(skb, protoh,		\
+						   entry_saddr,		\
+						   entry_daddr);	\
 	} while (0)
 
 #else
 
-#define TP_STORE_ADDR_PORTS_SKB(__entry, skb, protoh)		\
-	TP_STORE_ADDR_PORTS_SKB_V4(__entry, skb, protoh)
+#define TP_STORE_ADDR_PORTS_SKB(skb, protoh, entry_saddr, entry_daddr)	\
+	TP_STORE_ADDR_PORTS_SKB_V4(skb, protoh, entry_saddr, entry_daddr)
 
 #endif
 
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 1db95175c1e5..cf14b6fcbeed 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -295,7 +295,7 @@ DECLARE_EVENT_CLASS(tcp_event_skb,
 		memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
 		memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
 
-		TP_STORE_ADDR_PORTS_SKB(__entry, skb, th);
+		TP_STORE_ADDR_PORTS_SKB(skb, th, __entry->saddr, __entry->daddr);
 	),
 
 	TP_printk("skbaddr=%p src=%pISpc dest=%pISpc",
diff --git a/include/trace/events/udp.h b/include/trace/events/udp.h
index 62bebe2a6ece..6142be4068e2 100644
--- a/include/trace/events/udp.h
+++ b/include/trace/events/udp.h
@@ -38,7 +38,7 @@ TRACE_EVENT(udp_fail_queue_rcv_skb,
 		memset(__entry->saddr, 0, sizeof(struct sockaddr_in6));
 		memset(__entry->daddr, 0, sizeof(struct sockaddr_in6));
 
-		TP_STORE_ADDR_PORTS_SKB(__entry, skb, uh);
+		TP_STORE_ADDR_PORTS_SKB(skb, uh, __entry->saddr, __entry->daddr);
 	),
 
 	TP_printk("rc=%d family=%s src=%pISpc dest=%pISpc", __entry->rc,
-- 
2.37.3


^ permalink raw reply related	[flat|nested] 4+ messages in thread

* [PATCH net-next v4 2/2] trace: tcp: fully support trace_tcp_send_reset
  2024-04-01  7:36 [PATCH net-next v4 0/2] tcp: make trace of reset logic complete Jason Xing
  2024-04-01  7:36 ` [PATCH net-next v4 1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters Jason Xing
@ 2024-04-01  7:36 ` Jason Xing
  2024-04-04  2:30 ` [PATCH net-next v4 0/2] tcp: make trace of reset logic complete patchwork-bot+netdevbpf
  2 siblings, 0 replies; 4+ messages in thread
From: Jason Xing @ 2024-04-01  7:36 UTC (permalink / raw)
  To: edumazet, mhiramat, mathieu.desnoyers, rostedt, kuba, pabeni,
	davem
  Cc: netdev, linux-trace-kernel, kerneljasonxing, Jason Xing

From: Jason Xing <kernelxing@tencent.com>

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 <kernelxing@tencent.com>
---
 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 cf14b6fcbeed..5c04a61a11c2 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 a22ee5838751..0d47b48f8cfd 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 3f4cba49e9ee..8e9c59b6c00c 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);
-- 
2.37.3


^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [PATCH net-next v4 0/2] tcp: make trace of reset logic complete
  2024-04-01  7:36 [PATCH net-next v4 0/2] tcp: make trace of reset logic complete Jason Xing
  2024-04-01  7:36 ` [PATCH net-next v4 1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters Jason Xing
  2024-04-01  7:36 ` [PATCH net-next v4 2/2] trace: tcp: fully support trace_tcp_send_reset Jason Xing
@ 2024-04-04  2:30 ` patchwork-bot+netdevbpf
  2 siblings, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2024-04-04  2:30 UTC (permalink / raw)
  To: Jason Xing
  Cc: edumazet, mhiramat, mathieu.desnoyers, rostedt, kuba, pabeni,
	davem, netdev, linux-trace-kernel, kernelxing

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon,  1 Apr 2024 15:36:03 +0800 you wrote:
> From: Jason Xing <kernelxing@tencent.com>
> 
> Before this, we miss some cases where the TCP layer could send RST but
> we cannot trace it. So I decided to complete it :)
> 
> v4
> Link: https://lore.kernel.org/all/20240329034243.7929-1-kerneljasonxing@gmail.com/
> 1. rebased against latest net-next
> 2. remove {} and add skb test statement (Eric)
> 3. drop v3 patch [3/3] temporarily because 1) location is not that useful
> since we can use perf or something else to trace, 2) Eric said we could
> use drop_reason to show why we have to RST, which is good, but this seems
> not work well for those ->send_reset() logic. I need more time to
> investigate this part.
> 
> [...]

Here is the summary with links:
  - [net-next,v4,1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters
    https://git.kernel.org/netdev/net-next/c/9807080e2170
  - [net-next,v4,2/2] trace: tcp: fully support trace_tcp_send_reset
    https://git.kernel.org/netdev/net-next/c/19822a980e19

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2024-04-04  2:30 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-04-01  7:36 [PATCH net-next v4 0/2] tcp: make trace of reset logic complete Jason Xing
2024-04-01  7:36 ` [PATCH net-next v4 1/2] trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters Jason Xing
2024-04-01  7:36 ` [PATCH net-next v4 2/2] trace: tcp: fully support trace_tcp_send_reset Jason Xing
2024-04-04  2:30 ` [PATCH net-next v4 0/2] tcp: make trace of reset logic complete patchwork-bot+netdevbpf

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).