#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/netlink.h>#define NETLINK_USER 22
#define USER_MSG (NETLINK_USER + 1)
#define USER_PORT 50　　/*此处是写死了，可以用进程ID，表示来自用户态的唯一进程*/MODULE_LICENSE("GPL");
MODULE_AUTHOR("arvik");
MODULE_DESCRIPTION("netlink_demo");static void test_netlink_rcv(struct sk_buff *skb);struct netlink_kernel_cfg cfg = {.input = test_netlink_rcv,/*...*/
};
static struct sock *test_netlink_sock = NULL;int send_msg(int8_t *pbuf, uint16_t len)
{struct sk_buff *nl_skb;struct nlmsghdr *nlh;int ret;nl_skb = nlmsg_new(len, GFP_ATOMIC);if (!nl_skb) {printk("netlink_alloc_skb error\n");return -1;}/*将header填充到skb中*/nlh = nlmsg_put(nl_skb, 0, 0, USER_MSG, len, 0);if (nlh == NULL) {printk("put error\n");nlmsg_free(nl_skb);return -1;}/*拷贝data*/memcpy(nlmsg_data(nlh), pbuf, len);/*发送*/ret = netlink_unicast(test_netlink_sock, nl_skb, USER_PORT, MSG_DONTWAIT);return ret;
}static void test_netlink_rcv(struct sk_buff *skb)
{struct nlmsghdr *nlh = NULL;void *data = NULL;printk("skb->len %u\n", skb->len);if (skb->len >= nlmsg_total_size(0)){nlh = nlmsg_hdr(skb);data = NLMSG_DATA(nlh);if (data) {printk("kernel receive date : %s\n", (int8_t *)data);send_msg(data, nlmsg_len(nlh));}}
}static int __init test_netlink_init(void)
{printk("test netlink init\n");test_netlink_sock = netlink_kernel_create(&init_net, USER_MSG, &cfg);    if (test_netlink_sock == NULL) {printk("test netlink init error\n");return -1;}printk("test netlink init ok\n");return 0;
}
static void __exit test_netlink_exit(void)
{netlink_kernel_release(test_netlink_sock);test_netlink_sock = NULL;printk("test netlink exit\n");
}module_init(test_netlink_init);
module_exit(test_netlink_exit);

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <string.h>
#include <linux/netlink.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>#define NETLINK_USER 22
#define USER_MSG (NETLINK_USER + 1)#define MSG_LEN 100#define MAX_PLOAD 100struct _my_msg {struct nlmsghdr hdr;int8_t data[MSG_LEN];
};int main()
{char *data = "hello kernel";socklen_t addr_len;struct sockaddr_nl local, dest_addr;int skfd;struct nlmsghdr *nlh = NULL;struct _my_msg info;int ret;//创建socketskfd = socket(AF_NETLINK, SOCK_RAW, USER_MSG);if (skfd == (-1)) {fprintf(stderr, "create socket error...%s\n", strerror(errno));return (-1);}/*绑定*/memset(&local, 0, sizeof(local));local.nl_family =  AF_NETLINK;local.nl_pid = 50;　　/*此处的pid通常用进程ID，表示来自用户态的唯一进程*/local.nl_groups = 0;if (bind(skfd, (struct sockaddr *)&local, sizeof(local)) != 0) {fprintf(stderr, "bind error\n");close(skfd);return (-1);}//初始化目的地址memset(&dest_addr, 0, sizeof(dest_addr));dest_addr.nl_family = AF_NETLINK; dest_addr.nl_pid = 0;dest_addr.nl_groups = 0;/*填写data*/nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PLOAD));memset(nlh, 0, sizeof(struct nlmsghdr));nlh->nlmsg_len = NLMSG_SPACE(MAX_PLOAD);nlh->nlmsg_flags = 0;nlh->nlmsg_type = 0;nlh->nlmsg_seq = 0;nlh->nlmsg_pid = local.nl_pid;memcpy(NLMSG_DATA(nlh), data, strlen(data));ret = sendto(skfd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *)&dest_addr, sizeof(struct sockaddr_nl));if (ret < 0) {
//        fprintf(stderr, "sendto error\n");perror("sendto error: ");close(skfd);return (-1);}printf("wait kernel msg!\n");memset(&info, 0, sizeof(info));/*接受信息*/ret = recvfrom(skfd, &info, sizeof(struct _my_msg), 0, (struct sockaddr *)&dest_addr, &addr_len);if (ret <= 0) {
//        fprintf(stderr, "recv from kernel  error\n");perror("recv from kernel error: ");close(skfd);return (-1);}printf("msg receive from kernel : %s\n", info.data);close(skfd);free((void *)nlh);close(skfd);return 0;
}