Re: [RFC PATCH] net: diag: support SOCK_DESTROY for UDP sockets

This implements SOCK_DESTROY for UDP sockets similar to what was done
for TCP with commit c1e64e298b8ca ("net: diag: Support destroying TCP
sockets.") A process with a UDP socket targeted for destroy is awakened
and recvmsg fails with ECONNABORTED giving the process notice that
it should close the socket.

Signed-off-by: David Ahern <redacted>
---
 include/net/udp.h   |  8 ++++++++
 net/ipv4/udp.c      | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/ipv4/udp_diag.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 net/ipv6/udp.c      | 45 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 166 insertions(+)

diff --git a/include/net/udp.h b/include/net/udp.h
index 8894d7144189..5c3443634b4d 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h

@@ -251,6 +251,7 @@ int udp_get_port(struct sock *sk, unsigned short snum,
 		 int (*saddr_cmp)(const struct sock *,
 				  const struct sock *));
 void udp_err(struct sk_buff *, u32);
+int udp_abort(struct sock *sk, int err);
 int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
 int udp_push_pending_frames(struct sock *sk);
 void udp_flush_pending_frames(struct sock *sk);

@@ -274,6 +275,9 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 			       struct udp_table *tbl, struct sk_buff *skb);
 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
 				 __be16 sport, __be16 dport);
+struct sock *udp4_lib_lookup_full(struct net *net, __be32 saddr,
+				  __be16 sport, __be32 daddr, __be16 dport,
+				  int dif, struct udp_table *table);
 struct sock *udp6_lib_lookup(struct net *net,
 			     const struct in6_addr *saddr, __be16 sport,
 			     const struct in6_addr *daddr, __be16 dport,

@@ -286,6 +290,10 @@ struct sock *__udp6_lib_lookup(struct net *net,
 struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
 				 __be16 sport, __be16 dport);
 
+struct sock *udp6_lib_lookup_full(struct net *net,
+				  const struct in6_addr *saddr, __be16 sport,
+				  const struct in6_addr *daddr, __be16 dport,
+				  int dif, struct udp_table *table);
 /*
  * 	SNMP statistics for UDP and UDP-Lite
  */

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e61f7cd65d08..e5b72a7165e1 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c

@@ -594,6 +594,47 @@ struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
 #endif
 
+/* caller should hold rcu lock */
+struct sock *udp4_lib_lookup_full(struct net *net, __be32 saddr,
+				  __be16 sport, __be32 daddr, __be16 dport,
+				  int dif, struct udp_table *table)
+{
+	struct sock *sk;
+	int i;
+
+	for (i = 0; i <= table->mask; i++) {
+		struct udp_hslot *hslot = &table->hash[i];
+
+		sk_for_each_rcu(sk, &hslot->head) {
+			struct inet_sock *inet;
+
+			if (!net_eq(sock_net(sk), net) ||
+			    ipv6_only_sock(sk))
+				continue;
+
+			if (dif && sk->sk_bound_dev_if != dif)
+				continue;
+
+			if (sk->sk_family != PF_INET)
+				continue;
+
+			if (udp_sk(sk)->udp_port_hash != ntohs(sport))
+				continue;
+
+			inet = inet_sk(sk);
+			if (inet->inet_rcv_saddr != saddr  ||
+			    inet->inet_daddr     != daddr  ||
+			    inet->inet_dport     != dport)
+				continue;
+
+			return sk;
+		}
+	}
+
+	return NULL;
+}