1
2
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{
94 static u32 seq;
95 struct sk_buff *skb = NULL;
96 struct nlmsghdr *nlh;
97 int ret = 0;
98
99 if (group > ND_MAX_GROUP)
100 return -EINVAL;
101
102 if (!netlink_has_listeners(sock, group + 1))
103 return -ESRCH;
104
105 skb = alloc_skb(NLMSG_SPACE(len), GFP_ATOMIC);
106 if (!skb)
107 return -ENOMEM;
108
109 seq++;
110
111 nlh = nlmsg_put(skb, 0, seq, type, len, 0);
112 memcpy(NLMSG_DATA(nlh), msg, len);
113 NETLINK_CB(skb).portid = 0;
114 NETLINK_CB(skb).dst_group = 0;
115
116 ret = netlink_broadcast(sock, skb, 0, group + 1, GFP_ATOMIC);
117 if (!ret)
118 return len;
119
120 if (ret != -ESRCH)
121 pr_err("nl broadcast g=%d, t=%d, l=%d, r=%d\n",
122 group, type, len, ret);
123 else if (netlink_has_listeners(sock, group + 1))
124 return -EAGAIN;
125
126 return ret;
127}
128
