net: sockev: Initial Commit

Added module which subscribes to socket notifier events. Notifier events
are then converted to a multicast netlink message for user space
applications to consume.

CRs-Fixed:  626021
Change-Id: Id5c6808d972b69f5f065d7fba9094e75c6ad0b2c
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>
[subashab@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

include/uapi/linux/Kbuild

@@ -385,6 +385,7 @@ header-y += smiapp.h
 header-y += snmp.h
 header-y += sock_diag.h
 header-y += socket.h
+header-y += sockev.h
 header-y += sockios.h
 header-y += sonet.h
 header-y += sonypi.h

include/uapi/linux/netlink.h

@@ -27,7 +27,7 @@
 #define NETLINK_ECRYPTFS	19
 #define NETLINK_RDMA		20
 #define NETLINK_CRYPTO		21	/* Crypto layer */
-
+#define NETLINK_SOCKEV		22	/* Socket Administrative Events */
 #define NETLINK_INET_DIAG	NETLINK_SOCK_DIAG
 
 #define MAX_LINKS 32		

include/uapi/linux/sockev.h

@@ -0,0 +1,31 @@
+#ifndef _SOCKEV_H_
+#define _SOCKEV_H_
+
+#include <linux/types.h>
+#include <linux/netlink.h>
+#include <linux/socket.h>
+
+enum sknetlink_groups {
+	SKNLGRP_UNICAST,
+	SKNLGRP_SOCKEV,
+	__SKNLGRP_MAX
+};
+
+#define SOCKEV_STR_MAX 32
+
+/********************************************************************
+*		Socket operation messages
+****/
+
+struct sknlsockevmsg {
+	__u8 event[SOCKEV_STR_MAX];
+	__u32 pid; /* (struct task_struct*)->pid */
+	__u16 skfamily; /* (struct socket*)->sk->sk_family */
+	__u8 skstate; /* (struct socket*)->sk->sk_state */
+	__u8 skprotocol; /* (struct socket*)->sk->sk_protocol */
+	__u16 sktype; /* (struct socket*)->sk->sk_type */
+	__u64 skflags; /* (struct socket*)->sk->sk_flags */
+};
+
+#endif /* _SOCKEV_H_ */
+

net/Kconfig

@@ -312,6 +312,15 @@ config NET_FLOW_LIMIT
 	  with many clients some protection against DoS by a single (spoofed)
 	  flow that greatly exceeds average workload.
 
+config SOCKEV_NLMCAST
+	bool "Enable SOCKEV Netlink Multicast"
+	default n
+	---help---
+	  Default client for SOCKEV notifier events. Sends multicast netlink
+	  messages whenever the socket event notifier is invoked. Enable if
+	  user space entities need to be notified of socket events without
+	  having to poll /proc
+
 menu "Network testing"
 
 config NET_PKTGEN

net/core/Makefile

@@ -24,3 +24,4 @@ obj-$(CONFIG_NET_PTP_CLASSIFY) += ptp_classifier.o
 obj-$(CONFIG_CGROUP_NET_PRIO) += netprio_cgroup.o
 obj-$(CONFIG_CGROUP_NET_CLASSID) += netclassid_cgroup.o
 obj-$(CONFIG_LWTUNNEL) += lwtunnel.o
+obj-$(CONFIG_SOCKEV_NLMCAST) += sockev_nlmcast.o

net/core/sockev_nlmcast.c

@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ *
+ * Default SOCKEV client implementation
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/netlink.h>
+#include <linux/sockev.h>
+#include <net/sock.h>
+
+static int registration_status;
+static struct sock *socknlmsgsk;
+
+static void sockev_skmsg_recv(struct sk_buff *skb)
+{
+	pr_debug("%s(): Got unsolicited request\n", __func__);
+}
+
+static struct netlink_kernel_cfg nlcfg = {
+	.input = sockev_skmsg_recv
+};
+
+static void _sockev_event(unsigned long event, __u8 *evstr, int buflen)
+{
+	switch (event) {
+	case SOCKEV_SOCKET:
+		strlcpy(evstr, "SOCKEV_SOCKET", buflen);
+		break;
+	case SOCKEV_BIND:
+		strlcpy(evstr, "SOCKEV_BIND", buflen);
+		break;
+	case SOCKEV_LISTEN:
+		strlcpy(evstr, "SOCKEV_LISTEN", buflen);
+		break;
+	case SOCKEV_ACCEPT:
+		strlcpy(evstr, "SOCKEV_ACCEPT", buflen);
+		break;
+	case SOCKEV_CONNECT:
+		strlcpy(evstr, "SOCKEV_CONNECT", buflen);
+		break;
+	case SOCKEV_SHUTDOWN:
+		strlcpy(evstr, "SOCKEV_SHUTDOWN", buflen);
+		break;
+	default:
+		strlcpy(evstr, "UNKOWN", buflen);
+	}
+}
+
+static int sockev_client_cb(struct notifier_block *nb,
+			    unsigned long event, void *data)
+{
+
+	struct sk_buff *skb;
+	struct nlmsghdr *nlh;
+	struct sknlsockevmsg *smsg;
+	struct socket *sock;
+
+	sock = (struct socket *)data;
+	if (socknlmsgsk == 0)
+		goto done;
+	if ((socknlmsgsk == NULL) || (sock == NULL) || (sock->sk == NULL))
+		goto done;
+
+	skb = nlmsg_new(sizeof(struct sknlsockevmsg), GFP_KERNEL);
+	if (skb == NULL)
+		goto done;
+
+	nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct sknlsockevmsg), 0);
+	if (nlh == NULL) {
+		kfree_skb(skb);
+		goto done;
+	}
+
+	NETLINK_CB(skb).dst_group = SKNLGRP_SOCKEV;
+
+	smsg = nlmsg_data(nlh);
+	smsg->pid = current->pid;
+	_sockev_event(event, smsg->event, sizeof(smsg->event));
+	smsg->skfamily = sock->sk->sk_family;
+	smsg->skstate = sock->sk->sk_state;
+	smsg->skprotocol = sock->sk->sk_protocol;
+	smsg->sktype = sock->sk->sk_type;
+	smsg->skflags = sock->sk->sk_flags;
+
+	nlmsg_notify(socknlmsgsk, skb, 0, SKNLGRP_SOCKEV, 0, GFP_KERNEL);
+done:
+	return 0;
+}
+
+static struct notifier_block sockev_notifier_client = {
+	.notifier_call = sockev_client_cb,
+	.next = 0,
+	.priority = 0
+};
+
+/* ***************** Startup/Shutdown *************************************** */
+
+static int __init sockev_client_init(void)
+{
+	int rc;
+	registration_status = 1;
+	rc = sockev_register_notify(&sockev_notifier_client);
+	if (rc != 0) {
+		registration_status = 0;
+		pr_err("%s(): Failed to register cb (%d)\n", __func__, rc);
+	}
+	socknlmsgsk = netlink_kernel_create(&init_net, NETLINK_SOCKEV, &nlcfg);
+	if (!socknlmsgsk) {
+		pr_err("%s(): Failed to initialize netlink socket\n", __func__);
+		if (registration_status)
+			sockev_unregister_notify(&sockev_notifier_client);
+		registration_status = 0;
+	}
+
+	return rc;
+}
+static void __exit sockev_client_exit(void)
+{
+	if (registration_status)
+		sockev_unregister_notify(&sockev_notifier_client);
+}
+module_init(sockev_client_init)
+module_exit(sockev_client_exit)
+MODULE_LICENSE("GPL v2");
+