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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,
92 void *msg, int len))
93{
94 struct sock *sock;
95 struct netlink_kernel_cfg cfg = {
96 .input = netlink_rcv,
97 };
98
99#if !defined(DEFINE_MUTEX)
100 init_MUTEX(&netlink_mutex);
101#endif
102
103 sock = netlink_kernel_create(&init_net, unit, &cfg);
104
105 if (sock)
106 rcv_cb = cb;
107
108 return sock;
109}
110
111int netlink_send(struct sock *sock, int group, u16 type, void *msg, int len)
112{
113 static u32 seq;
114 struct sk_buff *skb = NULL;
115 struct nlmsghdr *nlh;
116 int ret = 0;
117
118 if (group > ND_MAX_GROUP)
119 return -EINVAL;
120
121 if (!netlink_has_listeners(sock, group + 1))
122 return -ESRCH;
123
124 skb = alloc_skb(NLMSG_SPACE(len), GFP_ATOMIC);
125 if (!skb)
126 return -ENOMEM;
127
128 seq++;
129
130 nlh = nlmsg_put(skb, 0, seq, type, len, 0);
131 memcpy(NLMSG_DATA(nlh), msg, len);
132 NETLINK_CB(skb).portid = 0;
133 NETLINK_CB(skb).dst_group = 0;
134
135 ret = netlink_broadcast(sock, skb, 0, group + 1, GFP_ATOMIC);
136 if (!ret)
137 return len;
138
139 if (ret != -ESRCH)
140 pr_err("nl broadcast g=%d, t=%d, l=%d, r=%d\n",
141 group, type, len, ret);
142 else if (netlink_has_listeners(sock, group + 1))
143 return -EAGAIN;
144
145 return ret;
146}
147