Mailing List Archive

From: Peilin He <he.peilin@zte.com.cn>

Introduce a tracepoint for icmp_send, which can help users to get more
detail information conveniently when icmp abnormal events happen.

1. Giving an usecase example:
=============================
When an application experiences packet loss due to an unreachable UDP
destination port, the kernel will send an exception message through the
icmp_send function. By adding a trace point for icmp_send, developers or
system administrators can obtain detailed information about the UDP
packet loss, including the type, code, source address, destination address,
source port, and destination port. This facilitates the trouble-shooting
of UDP packet loss issues especially for those network-service
applications.

2. Operation Instructions:
==========================
Switch to the tracing directory.
cd /sys/kernel/tracing
Filter for destination port unreachable.
echo "type==3 && code==3" > events/icmp/icmp_send/filter
Enable trace event.
echo 1 > events/icmp/icmp_send/enable

3. Result View:
================
udp_client_erro-11370 [002] ...s.12 124.728002:
icmp_send: icmp_send: type=3, code=3.
From 127.0.0.1:41895 to 127.0.0.1:6666 ulen=23
skbaddr=00000000589b167a

Change log
==========
v5->v6:
Some fixes according to
https://lore.kernel.org/all/20240413161319.GA853376@kernel.org/
1.Resubmit patches based on the latest net-next code.

v4->v5:
Some fixes according to
https://lore.kernel.org/all/CAL+tcoDeXXh+zcRk4PHnUk8ELnx=CE2pcCqs7sFm0y9aK-Eehg@mail.gmail.com/
1.Adjust the position of trace_icmp_send() to before icmp_push_reply().

v3->v4:
Some fixes according to
https://lore.kernel.org/all/CANn89i+EFEr7VHXNdOi59Ba_R1nFKSBJzBzkJFVgCTdXBx=YBg@mail.gmail.com/
1.Add legality check for UDP header in SKB.
2.Target this patch for net-next.

v2->v3:
Some fixes according to
https://lore.kernel.org/all/20240319102549.7f7f6f53@gandalf.local.home/
1. Change the tracking directory to/sys/kernel/tracking.
2. Adjust the layout of the TP-STRUCT_entry parameter structure.

v1->v2:
Some fixes according to
https://lore.kernel.org/all/CANn89iL-y9e_VFpdw=sZtRnKRu_tnUwqHuFQTJvJsv-nz1xPDw@mail.gmail.com/
1. adjust the trace_icmp_send() to more protocols than UDP.
2. move the calling of trace_icmp_send after sanity checks
in __icmp_send().

Signed-off-by: Peilin He <he.peilin@zte.com.cn>
Reviewed-by: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Liu Chun <liu.chun2@zte.com.cn>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
---
include/trace/events/icmp.h | 65 +++++++++++++++++++++++++++++++++++++
net/ipv4/icmp.c | 4 +++
2 files changed, 69 insertions(+)
create mode 100644 include/trace/events/icmp.h

diff --git a/include/trace/events/icmp.h b/include/trace/events/icmp.h
new file mode 100644
index 000000000000..7d5190f48a28
--- /dev/null
+++ b/include/trace/events/icmp.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM icmp
+
+#if !defined(_TRACE_ICMP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ICMP_H
+
+#include <linux/icmp.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(icmp_send,
+
+ TP_PROTO(const struct sk_buff *skb, int type, int code),
+
+ TP_ARGS(skb, type, code),
+
+ TP_STRUCT__entry(
+ __field(const void *, skbaddr)
+ __field(int, type)
+ __field(int, code)
+ __array(__u8, saddr, 4)
+ __array(__u8, daddr, 4)
+ __field(__u16, sport)
+ __field(__u16, dport)
+ __field(unsigned short, ulen)
+ ),
+
+ TP_fast_assign(
+ struct iphdr *iph = ip_hdr(skb);
+ int proto_4 = iph->protocol;
+ __be32 *p32;
+
+ __entry->skbaddr = skb;
+ __entry->type = type;
+ __entry->code = code;
+
+ struct udphdr *uh = udp_hdr(skb);
+ if (proto_4 != IPPROTO_UDP || (u8 *)uh < skb->head ||
+ (u8 *)uh + sizeof(struct udphdr) > skb_tail_pointer(skb)) {
+ __entry->sport = 0;
+ __entry->dport = 0;
+ __entry->ulen = 0;
+ } else {
+ __entry->sport = ntohs(uh->source);
+ __entry->dport = ntohs(uh->dest);
+ __entry->ulen = ntohs(uh->len);
+ }
+
+ p32 = (__be32 *) __entry->saddr;
+ *p32 = iph->saddr;
+
+ p32 = (__be32 *) __entry->daddr;
+ *p32 = iph->daddr;
+ ),
+
+ TP_printk("icmp_send: type=%d, code=%d. From %pI4:%u to %pI4:%u ulen=%d skbaddr=%p",
+ __entry->type, __entry->code,
+ __entry->saddr, __entry->sport, __entry->daddr,
+ __entry->dport, __entry->ulen, __entry->skbaddr)
+);
+
+#endif /* _TRACE_ICMP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
\ No newline at end of file
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 8cebb476b3ab..30b302492613 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -92,6 +92,8 @@
#include <net/inet_common.h>
#include <net/ip_fib.h>
#include <net/l3mdev.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/icmp.h>

/*
* Build xmit assembly blocks
@@ -762,6 +764,8 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
if (!fl4.saddr)
fl4.saddr = htonl(INADDR_DUMMY);

+ trace_icmp_send(skb_in, type, code);
+
icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
ende:
ip_rt_put(rt);
--
2.17.1