1/*
2 * Copyright (c) 2012 GCT Semiconductor, Inc. All rights reserved.
3 *
4 * This software is licensed under the terms of the GNU General Public
5 * License version 2, as published by the Free Software Foundation, and
6 * may be copied, distributed, and modified under those terms.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/export.h>
17#include <linux/etherdevice.h>
18#include <linux/netlink.h>
19#include <asm/byteorder.h>
20#include <net/sock.h>
21
22#include "netlink_k.h"
23
24#if defined(DEFINE_MUTEX)
25static DEFINE_MUTEX(netlink_mutex);
26#else
27static struct semaphore netlink_mutex;
28#define mutex_lock(x)		down(x)
29#define mutex_unlock(x)		up(x)
30#endif
31
32#define ND_MAX_GROUP		30
33#define ND_IFINDEX_LEN		sizeof(int)
34#define ND_NLMSG_SPACE(len)	(NLMSG_SPACE(len) + ND_IFINDEX_LEN)
35#define ND_NLMSG_DATA(nlh)	((void *)((char *)NLMSG_DATA(nlh) + \
36						  ND_IFINDEX_LEN))
37#define ND_NLMSG_S_LEN(len)	(len+ND_IFINDEX_LEN)
38#define ND_NLMSG_R_LEN(nlh)	(nlh->nlmsg_len-ND_IFINDEX_LEN)
39#define ND_NLMSG_IFIDX(nlh)	NLMSG_DATA(nlh)
40#define ND_MAX_MSG_LEN		(1024 * 32)
41
42static void (*rcv_cb)(struct net_device *dev, u16 type, void *msg, int len);
43
44static void netlink_rcv_cb(struct sk_buff *skb)
45{
46	struct nlmsghdr	*nlh;
47	struct net_device *dev;
48	u32 mlen;
49	void *msg;
50	int ifindex;
51
52	if (!rcv_cb) {
53		pr_err("nl cb - unregistered\n");
54		return;
55	}
56
57	if (skb->len < NLMSG_HDRLEN) {
58		pr_err("nl cb - invalid skb length\n");
59		return;
60	}
61
62	nlh = (struct nlmsghdr *)skb->data;
63
64	if (skb->len < nlh->nlmsg_len || nlh->nlmsg_len > ND_MAX_MSG_LEN) {
65		pr_err("nl cb - invalid length (%d,%d)\n",
66		       skb->len, nlh->nlmsg_len);
67		return;
68	}
69
70	memcpy(&ifindex, ND_NLMSG_IFIDX(nlh), ND_IFINDEX_LEN);
71	msg = ND_NLMSG_DATA(nlh);
72	mlen = ND_NLMSG_R_LEN(nlh);
73
74	dev = dev_get_by_index(&init_net, ifindex);
75	if (dev) {
76		rcv_cb(dev, nlh->nlmsg_type, msg, mlen);
77		dev_put(dev);
78	} else {
79		pr_err("nl cb - dev (%d) not found\n", ifindex);
80	}
81}
82
83static void netlink_rcv(struct sk_buff *skb)
84{
85	mutex_lock(&netlink_mutex);
86	netlink_rcv_cb(skb);
87	mutex_unlock(&netlink_mutex);
88}
89
90struct sock *netlink_init(int unit,
91	void (*cb)(struct net_device *dev, u16 type, void *msg, int len))
92{
93	struct sock *sock;
94	struct netlink_kernel_cfg cfg = {
95		.input  = netlink_rcv,
96	};
97
98#if !defined(DEFINE_MUTEX)
99	init_MUTEX(&netlink_mutex);
100#endif
101
102	sock = netlink_kernel_create(&init_net, unit, &cfg);
103
104	if (sock)
105		rcv_cb = cb;
106
107	return sock;
108}
109
110void netlink_exit(struct sock *sock)
111{
112	sock_release(sock->sk_socket);
113}
114
115int netlink_send(struct sock *sock, int group, u16 type, void *msg, int len)
116{
117	static u32 seq;
118	struct sk_buff *skb = NULL;
119	struct nlmsghdr *nlh;
120	int ret = 0;
121
122	if (group > ND_MAX_GROUP)
123		return -EINVAL;
124
125	if (!netlink_has_listeners(sock, group+1))
126		return -ESRCH;
127
128	skb = alloc_skb(NLMSG_SPACE(len), GFP_ATOMIC);
129	if (!skb)
130		return -ENOMEM;
131
132	seq++;
133
134	nlh = nlmsg_put(skb, 0, seq, type, len, 0);
135	memcpy(NLMSG_DATA(nlh), msg, len);
136	NETLINK_CB(skb).portid = 0;
137	NETLINK_CB(skb).dst_group = 0;
138
139	ret = netlink_broadcast(sock, skb, 0, group+1, GFP_ATOMIC);
140	if (!ret)
141		return len;
142
143	if (ret != -ESRCH)
144		pr_err("nl broadcast g=%d, t=%d, l=%d, r=%d\n",
145		       group, type, len, ret);
146	else if (netlink_has_listeners(sock, group+1))
147		return -EAGAIN;
148
149	return ret;
150}
151