1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2012 GCT Semiconductor, Inc. All rights reserved. */
3
4#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
5
6#include <linux/export.h>
7#include <linux/mutex.h>
8#include <linux/etherdevice.h>
9#include <linux/netlink.h>
10#include <asm/byteorder.h>
11#include <net/sock.h>
12
13#include "netlink_k.h"
14
15static DEFINE_MUTEX(netlink_mutex);
16
17#define ND_MAX_GROUP		30
18#define ND_IFINDEX_LEN		sizeof(int)
19#define ND_NLMSG_SPACE(len)	(NLMSG_SPACE(len) + ND_IFINDEX_LEN)
20#define ND_NLMSG_DATA(nlh)	((void *)((char *)NLMSG_DATA(nlh) + \
21						  ND_IFINDEX_LEN))
22#define ND_NLMSG_S_LEN(len)	((len) + ND_IFINDEX_LEN)
23#define ND_NLMSG_R_LEN(nlh)	((nlh)->nlmsg_len - ND_IFINDEX_LEN)
24#define ND_NLMSG_IFIDX(nlh)	NLMSG_DATA(nlh)
25#define ND_MAX_MSG_LEN		(1024 * 32)
26
27static void (*rcv_cb)(struct net_device *dev, u16 type, void *msg, int len);
28
29static void netlink_rcv_cb(struct sk_buff *skb)
30{
31	struct nlmsghdr	*nlh;
32	struct net_device *dev;
33	u32 mlen;
34	void *msg;
35	int ifindex;
36
37	if (!rcv_cb) {
38		pr_err("nl cb - unregistered\n");
39		return;
40	}
41
42	if (skb->len < NLMSG_HDRLEN) {
43		pr_err("nl cb - invalid skb length\n");
44		return;
45	}
46
47	nlh = (struct nlmsghdr *)skb->data;
48
49	if (skb->len < nlh->nlmsg_len || nlh->nlmsg_len > ND_MAX_MSG_LEN) {
50		pr_err("nl cb - invalid length (%d,%d)\n",
51		       skb->len, nlh->nlmsg_len);
52		return;
53	}
54
55	memcpy(&ifindex, ND_NLMSG_IFIDX(nlh), ND_IFINDEX_LEN);
56	msg = ND_NLMSG_DATA(nlh);
57	mlen = ND_NLMSG_R_LEN(nlh);
58
59	dev = dev_get_by_index(&init_net, ifindex);
60	if (dev) {
61		rcv_cb(dev, nlh->nlmsg_type, msg, mlen);
62		dev_put(dev);
63	} else {
64		pr_err("nl cb - dev (%d) not found\n", ifindex);
65	}
66}
67
68static void netlink_rcv(struct sk_buff *skb)
69{
70	mutex_lock(&netlink_mutex);
71	netlink_rcv_cb(skb);
72	mutex_unlock(&netlink_mutex);
73}
74
75struct sock *netlink_init(int unit,
76			  void (*cb)(struct net_device *dev, u16 type,
77				     void *msg, int len))
78{
79	struct sock *sock;
80	struct netlink_kernel_cfg cfg = {
81		.input  = netlink_rcv,
82	};
83
84	sock = netlink_kernel_create(&init_net, unit, &cfg);
85
86	if (sock)
87		rcv_cb = cb;
88
89	return sock;
90}
91
92int netlink_send(struct sock *sock, int group, u16 type, void *msg, int len,
93		 struct net_device *dev)
94{
95	static u32 seq;
96	struct sk_buff *skb = NULL;
97	struct nlmsghdr *nlh;
98	int ret = 0;
99
100	if (group > ND_MAX_GROUP)
101		return -EINVAL;
102
103	if (!netlink_has_listeners(sock, group + 1))
104		return -ESRCH;
105
106	skb = alloc_skb(NLMSG_SPACE(len), GFP_ATOMIC);
107	if (!skb)
108		return -ENOMEM;
109
110	seq++;
111
112	nlh = nlmsg_put(skb, 0, seq, type, len, 0);
113	memcpy(NLMSG_DATA(nlh), msg, len);
114	NETLINK_CB(skb).portid = 0;
115	NETLINK_CB(skb).dst_group = 0;
116
117	ret = netlink_broadcast(sock, skb, 0, group + 1, GFP_ATOMIC);
118	if (!ret)
119		return len;
120
121	if (ret != -ESRCH)
122		netdev_err(dev, "nl broadcast g=%d, t=%d, l=%d, r=%d\n",
123			   group, type, len, ret);
124	else if (netlink_has_listeners(sock, group + 1))
125		return -EAGAIN;
126
127	return ret;
128}
129