[RESEND PATCH bpf-next v4 1/2] bpf, sockmap: Introduce tracing capability for sockmap

[Jiayuan Chen <jiayuan.chen@linux.dev>]

Sockmap has the same high-performance forwarding capability as XDP, but
operates at Layer 7.

Introduce tracing capability for sockmap, to trace the execution results
of BPF programs without modifying the programs themselves, similar to
the existing trace_xdp_redirect{_map}.

It is crucial for debugging sockmap programs, especially in production
environments.

Additionally, the new header file has to be added to bpf_trace.h to
automatically generate tracepoints.

Test results:
$ echo "1" > /sys/kernel/tracing/events/sockmap/enable

msg/skb:
'''
sockmap_redirect: sk=000000000ec02a93, netns=4026531840, inode=318, \
family=2, protocol=6, prog_id=59, len=8192, type=msg, action=REDIRECT, \
redirect_type=ingress

sockmap_redirect: sk=00000000d5d9c931, netns=4026531840, inode=64731, \
family=2, protocol=6, prog_id=91, len=8221, type=skb, action=REDIRECT, \
redirect_type=egress

sockmap_redirect: sk=00000000106fc281, netns=4026531840, inode=64729, \
family=2, protocol=6, prog_id=94, len=8192, type=msg, action=PASS, \
redirect_type=none
'''

strparser:
'''
sockmap_strparser: sk=00000000f15fc1c8, netns=4026531840, inode=52396, \
family=2, protocol=6, prog_id=143, in_len=1000, full_len=10
'''

Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>

---
v3 -> v4: Resending this patch as v3 was incorrectly closed by Patchwork.
          Additionally, carrying the Reviewed-by tag.
v3: https://lore.kernel.org/all/20250414161153.14990-1-jiayuan.chen@linux.dev

v1 -> v2: Print more valuable information as suggested by the maintainer.
---
 MAINTAINERS                    |   1 +
 include/linux/bpf_trace.h      |   1 +
 include/trace/events/sockmap.h | 158 +++++++++++++++++++++++++++++++++
 net/core/skmsg.c               |   6 ++
 4 files changed, 166 insertions(+)
 create mode 100644 include/trace/events/sockmap.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 3cbf9ac0d83f..76d742b7fbd6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4429,6 +4429,7 @@ L:	netdev@vger.kernel.org
 L:	bpf@vger.kernel.org
 S:	Maintained
 F:	include/linux/skmsg.h
+F:	include/trace/events/sockmap.h
 F:	net/core/skmsg.c
 F:	net/core/sock_map.c
 F:	net/ipv4/tcp_bpf.c
diff --git a/include/linux/bpf_trace.h b/include/linux/bpf_trace.h
index ddf896abcfb6..d559be0a79c5 100644
--- a/include/linux/bpf_trace.h
+++ b/include/linux/bpf_trace.h
@@ -3,5 +3,6 @@
 #define __LINUX_BPF_TRACE_H__
 
 #include <trace/events/xdp.h>
+#include <trace/events/sockmap.h>
 
 #endif /* __LINUX_BPF_TRACE_H__ */
diff --git a/include/trace/events/sockmap.h b/include/trace/events/sockmap.h
new file mode 100644
index 000000000000..79784e8d5866
--- /dev/null
+++ b/include/trace/events/sockmap.h
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sockmap
+
+#if !defined(_TRACE_SOCKMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SOCKMAP_H
+
+#include <linux/tracepoint.h>
+#include <linux/bpf.h>
+#include <linux/skmsg.h>
+
+#ifndef __TRACE_SOCKMAP_HELPER_ONCE_ONLY
+#define __TRACE_SOCKMAP_HELPER_ONCE_ONLY
+
+enum sockmap_direct_type {
+	SOCKMAP_REDIR_NONE	= 0,
+	SOCKMAP_REDIR_INGRESS,
+	SOCKMAP_REDIR_EGRESS,
+};
+
+enum sockmap_data_type {
+	SOCKMAP_MSG		= 0,
+	SOCKMAP_SKB,
+};
+
+#endif /* end __TRACE_SOCKMAP_HELPER_ONCE_ONLY */
+
+TRACE_DEFINE_ENUM(SOCKMAP_MSG);
+TRACE_DEFINE_ENUM(SOCKMAP_SKB);
+TRACE_DEFINE_ENUM(SOCKMAP_REDIR_NONE);
+TRACE_DEFINE_ENUM(SOCKMAP_REDIR_INGRESS);
+TRACE_DEFINE_ENUM(SOCKMAP_REDIR_EGRESS);
+
+TRACE_DEFINE_ENUM(__SK_DROP);
+TRACE_DEFINE_ENUM(__SK_PASS);
+TRACE_DEFINE_ENUM(__SK_REDIRECT);
+TRACE_DEFINE_ENUM(__SK_NONE);
+
+#define show_redirect_type(x)					\
+	__print_symbolic(x,					\
+		{ SOCKMAP_REDIR_NONE,		"none" },	\
+		{ SOCKMAP_REDIR_INGRESS,	"ingress" },	\
+		{ SOCKMAP_REDIR_EGRESS,		"egress" })
+
+#define show_act(x)						\
+	__print_symbolic(x,					\
+		{ __SK_DROP,			"DROP" },	\
+		{ __SK_PASS,			"PASS" },	\
+		{ __SK_REDIRECT,		"REDIRECT" },	\
+		{ __SK_NONE,			"NONE" })
+
+#define show_data_type(x)					\
+	__print_symbolic(x,					\
+		{ SOCKMAP_MSG,			"msg" },	\
+		{ SOCKMAP_SKB,			"skb" })
+
+#define trace_sockmap_skmsg_redirect(sk, prog, msg, act)	\
+	trace_sockmap_redirect((sk), SOCKMAP_MSG, (prog),	\
+			       (msg)->sg.size, (act),		\
+			       sk_msg_to_ingress(msg))
+
+#define trace_sockmap_skb_redirect(sk, prog, skb, act)		\
+	trace_sockmap_redirect((sk), SOCKMAP_SKB, (prog),	\
+			       (skb)->len, (act),		\
+			       skb_bpf_ingress(skb))
+
+#define trace_sockmap_skb_strp_parse(sk, prog, skb, ret)	\
+	trace_sockmap_strparser((sk), (prog), (skb)->len, (ret))
+
+TRACE_EVENT(sockmap_redirect,
+
+	TP_PROTO(const struct sock *sk, enum sockmap_data_type type,
+		 const struct bpf_prog *prog, int len, int act,
+		 bool ingress),
+
+	TP_ARGS(sk, type, prog, len, act, ingress),
+
+	TP_STRUCT__entry(
+		__field(const void *, sk)
+		__field(unsigned long, ino)
+		__field(unsigned int, netns_ino)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(int, prog_id)
+		__field(int, len)
+		__field(int, act)
+		__field(enum sockmap_data_type, type)
+		__field(enum sockmap_direct_type, redir)
+	),
+
+	TP_fast_assign(
+		/* 'redir' is undefined if action is not REDIRECT */
+		enum sockmap_direct_type redir = SOCKMAP_REDIR_NONE;
+
+		if (act == __SK_REDIRECT) {
+			if (ingress)
+				redir = SOCKMAP_REDIR_INGRESS;
+			else
+				redir = SOCKMAP_REDIR_EGRESS;
+		}
+		__entry->sk		= sk;
+		__entry->ino		= sock_i_ino((struct sock *)sk);
+		__entry->netns_ino	= sock_net(sk)->ns.inum;
+		__entry->type		= type;
+		__entry->family		= sk->sk_family;
+		__entry->protocol	= sk->sk_protocol;
+		__entry->prog_id	= prog->aux->id;
+		__entry->len		= len;
+		__entry->act		= act;
+		__entry->redir		= redir;
+	),
+
+	TP_printk("sk=%p, netns=%u, inode=%lu, family=%u, protocol=%u,"
+		  " prog_id=%d, len=%d, type=%s, action=%s, redirect_type=%s",
+		  __entry->sk, __entry->netns_ino, __entry->ino,
+		  __entry->family, __entry->protocol, __entry->prog_id,
+		  __entry->len, show_data_type(__entry->type),
+		  show_act(__entry->act), show_redirect_type(__entry->redir))
+);
+
+TRACE_EVENT(sockmap_strparser,
+
+	TP_PROTO(const struct sock *sk, const struct bpf_prog *prog,
+		 int in_len, int full_len),
+
+	TP_ARGS(sk, prog, in_len, full_len),
+
+	TP_STRUCT__entry(
+		__field(const void *, sk)
+		__field(unsigned long, ino)
+		__field(unsigned int, netns_ino)
+		__field(__u16, family)
+		__field(__u16, protocol)
+		__field(int, prog_id)
+		__field(int, in_len)
+		__field(int, full_len)
+	),
+
+	TP_fast_assign(
+		__entry->sk		= sk;
+		__entry->ino		= sock_i_ino((struct sock *)sk);
+		__entry->netns_ino	= sock_net(sk)->ns.inum;
+		__entry->family		= sk->sk_family;
+		__entry->protocol	= sk->sk_protocol;
+		__entry->prog_id	= prog->aux->id;
+		__entry->in_len		= in_len;
+		__entry->full_len	= full_len;
+	),
+
+	TP_printk("sk=%p, netns=%u, inode=%lu, family=%u, protocol=%u,"
+		  " prog_id=%d, in_len=%d, full_len=%d",
+		  __entry->sk, __entry->netns_ino, __entry->ino,
+		  __entry->family, __entry->protocol, __entry->prog_id,
+		  __entry->in_len, __entry->full_len)
+);
+#endif /* _TRACE_SOCKMAP_H */
+
+#include <trace/define_trace.h>
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 276934673066..517596efafa8 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -9,6 +9,7 @@
 #include <net/tcp.h>
 #include <net/tls.h>
 #include <trace/events/sock.h>
+#include <trace/events/sockmap.h>
 
 static bool sk_msg_try_coalesce_ok(struct sk_msg *msg, int elem_first_coalesce)
 {
@@ -910,6 +911,7 @@ int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
 		sock_hold(psock->sk_redir);
 	}
 out:
+	trace_sockmap_skmsg_redirect(sk, prog, msg, ret);
 	rcu_read_unlock();
 	return ret;
 }
@@ -981,6 +983,7 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct sk_buff *skb)
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
 		skb->sk = NULL;
+		trace_sockmap_skb_redirect(psock->sk, prog, skb, ret);
 	}
 	sk_psock_tls_verdict_apply(skb, psock, ret);
 	rcu_read_unlock();
@@ -1090,6 +1093,7 @@ static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
 		skb_bpf_set_strparser(skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
 		skb->sk = NULL;
+		trace_sockmap_skb_redirect(sk, prog, skb, ret);
 	}
 	sk_psock_verdict_apply(psock, skb, ret);
 out:
@@ -1113,6 +1117,7 @@ static int sk_psock_strp_parse(struct strparser *strp, struct sk_buff *skb)
 		skb->sk = psock->sk;
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		skb->sk = NULL;
+		trace_sockmap_skb_strp_parse(psock->sk, prog, skb, ret);
 	}
 	rcu_read_unlock();
 	return ret;
@@ -1217,6 +1222,7 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb)
 		skb_bpf_redirect_clear(skb);
 		ret = bpf_prog_run_pin_on_cpu(prog, skb);
 		ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
+		trace_sockmap_skb_redirect(psock->sk, prog, skb, ret);
 	}
 	ret = sk_psock_verdict_apply(psock, skb, ret);
 	if (ret < 0)
-- 
2.47.1