sock_diag: define destruction multicast groups

These groups will contain socket-destruction events for
AF_INET/AF_INET6, IPPROTO_TCP/IPPROTO_UDP.

Near the end of socket destruction, a check for listeners is
performed.  In the presence of a listener, rather than completely
cleanup the socket, a unit of work will be added to a private
work queue which will first broadcast information about the socket
and then finish the cleanup operation.

Signed-off-by: Craig Gallek <kraig@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 53 insertions, 0 deletions

diff --git a/include/linux/sock_diag.h b/include/linux/sock_diag.h
index 083ac388098e..fddebc617469 100644
--- a/include/linux/sock_diag.h
+++ b/include/linux/sock_diag.h
@@ -1,7 +1,10 @@
 #ifndef __SOCK_DIAG_H__
 #define __SOCK_DIAG_H__
 
+#include <linux/netlink.h>
 #include <linux/user_namespace.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
 #include <uapi/linux/sock_diag.h>
 
 struct sk_buff;
@@ -11,6 +14,7 @@ struct sock;
 struct sock_diag_handler {
 	__u8 family;
 	int (*dump)(struct sk_buff *skb, struct nlmsghdr *nlh);
+	int (*get_info)(struct sk_buff *skb, struct sock *sk);
 };
 
 int sock_diag_register(const struct sock_diag_handler *h);
@@ -26,4 +30,42 @@ int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attr);
 int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
 			     struct sk_buff *skb, int attrtype);
 
+static inline
+enum sknetlink_groups sock_diag_destroy_group(const struct sock *sk)
+{
+	switch (sk->sk_family) {
+	case AF_INET:
+		switch (sk->sk_protocol) {
+		case IPPROTO_TCP:
+			return SKNLGRP_INET_TCP_DESTROY;
+		case IPPROTO_UDP:
+			return SKNLGRP_INET_UDP_DESTROY;
+		default:
+			return SKNLGRP_NONE;
+		}
+	case AF_INET6:
+		switch (sk->sk_protocol) {
+		case IPPROTO_TCP:
+			return SKNLGRP_INET6_TCP_DESTROY;
+		case IPPROTO_UDP:
+			return SKNLGRP_INET6_UDP_DESTROY;
+		default:
+			return SKNLGRP_NONE;
+		}
+	default:
+		return SKNLGRP_NONE;
+	}
+}
+
+static inline
+bool sock_diag_has_destroy_listeners(const struct sock *sk)
+{
+	const struct net *n = sock_net(sk);
+	const enum sknetlink_groups group = sock_diag_destroy_group(sk);
+
+	return group != SKNLGRP_NONE && n->diag_nlsk &&
+		netlink_has_listeners(n->diag_nlsk, group);
+}
+void sock_diag_broadcast_destroy(struct sock *sk);
+
 #endif
diff --git a/include/net/sock.h b/include/net/sock.h
index 26c1c3171e00..3e8258699270 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1518,6 +1518,7 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow)
 struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
 		      struct proto *prot, int kern);
 void sk_free(struct sock *sk);
+void sk_destruct(struct sock *sk);
 struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority);
 
 struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force,
diff --git a/include/uapi/linux/sock_diag.h b/include/uapi/linux/sock_diag.h
index b00e29efb161..49230d36f9ce 100644
--- a/include/uapi/linux/sock_diag.h
+++ b/include/uapi/linux/sock_diag.h
@@ -23,4 +23,14 @@ enum {
 	SK_MEMINFO_VARS,
 };
 
+enum sknetlink_groups {
+	SKNLGRP_NONE,
+	SKNLGRP_INET_TCP_DESTROY,
+	SKNLGRP_INET_UDP_DESTROY,
+	SKNLGRP_INET6_TCP_DESTROY,
+	SKNLGRP_INET6_UDP_DESTROY,
+	__SKNLGRP_MAX,
+};
+#define SKNLGRP_MAX	(__SKNLGRP_MAX - 1)
+
 #endif /* _UAPI__SOCK_DIAG_H__ */