netdev - [net-next 1/2] inet_diag: export SO_REUSEADDR and SO

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Date: Tue, 12 Sep 2023 10:31:48 -0400
From: Jason Baron <jbaron@...mai.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com
Cc: netdev@...r.kernel.org
Subject: [net-next 1/2] inet_diag: export SO_REUSEADDR and SO_REUSEPORT sockopts

Add the ability to monitor SO_REUSEADDR and SO_REUSEPORT for an inet
socket. These settings are currently readable via getsockopt().
We have an app that will sometimes fail to bind() and it's helpful to
understand what other apps are causing the bind() conflict.

Signed-off-by: Jason Baron <jbaron@...mai.com>
---
 include/linux/inet_diag.h      | 2 ++
 include/uapi/linux/inet_diag.h | 7 +++++++
 net/ipv4/inet_diag.c           | 7 +++++++
 3 files changed, 16 insertions(+)

diff --git a/include/linux/inet_diag.h b/include/linux/inet_diag.h
index 84abb30a3fbb..d05a4c26b13d 100644
--- a/include/linux/inet_diag.h
+++ b/include/linux/inet_diag.h
@@ -77,6 +77,8 @@ static inline size_t inet_diag_msg_attrs_size(void)
 #endif
 		+ nla_total_size(sizeof(struct inet_diag_sockopt))
 						     /* INET_DIAG_SOCKOPT */
+		+ nla_total_size(sizeof(struct inet_diag_reuse))
+						    /* INET_DIAG_REUSE */
 		;
 }
 int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
index 50655de04c9b..f93eeea1faba 100644
--- a/include/uapi/linux/inet_diag.h
+++ b/include/uapi/linux/inet_diag.h
@@ -161,6 +161,7 @@ enum {
 	INET_DIAG_SK_BPF_STORAGES,
 	INET_DIAG_CGROUP_ID,
 	INET_DIAG_SOCKOPT,
+	INET_DIAG_REUSE,
 	__INET_DIAG_MAX,
 };
 
@@ -201,6 +202,12 @@ struct inet_diag_sockopt {
 		unused:5;
 };
 
+struct inet_diag_reuse {
+	__u8	reuse:4,
+		reuseport:1,
+		unused:3;
+};
+
 /* INET_DIAG_VEGASINFO */
 
 struct tcpvegas_info {
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index e13a84433413..d6ebb1e612fc 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -125,6 +125,7 @@ int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
 			     bool net_admin)
 {
 	const struct inet_sock *inet = inet_sk(sk);
+	struct inet_diag_reuse inet_reuse = {};
 	struct inet_diag_sockopt inet_sockopt;
 
 	if (nla_put_u8(skb, INET_DIAG_SHUTDOWN, sk->sk_shutdown))
@@ -197,6 +198,12 @@ int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
 		    &inet_sockopt))
 		goto errout;
 
+	inet_reuse.reuse = sk->sk_reuse;
+	inet_reuse.reuseport = sk->sk_reuseport;
+	if (nla_put(skb, INET_DIAG_REUSE, sizeof(inet_reuse),
+		    &inet_reuse))
+		goto errout;
+
 	return 0;
 errout:
 	return 1;
-- 
2.25.1