用C网络链路套接字使用3.X linux内核(Netlink Sockets in C using

您好，我一直在努力试图让网络链路插座为3.2 Linux内核工作，但我似乎无法弄清楚如何做到这一点。我环顾四周为网络链路插座的基本知识的例子，但似乎所有我看到的是对2.6内核的例子。

我试图寻找的是如何利用网络链路插座一个内核模块，用户模式应用程序，反之亦然发送信息？

任何帮助将不胜感激。谢谢！

我一直在工作在内核中使用网络链路插槽以及跑进了同样的问题你。

使用此之前的堆栈溢出的答案为基础，我设法使它工作。 3.5至3.6的“netlink_kernel_create”功能改变了... ...和我在3.8。下面的代码应该为你工作。

netlinkKernel.c

#include <linux/module.h>
#include <net/sock.h>
#include <linux/netlink.h>
#include <linux/skbuff.h>


#define NETLINK_USER 31

struct sock *nl_sk = NULL;

static void hello_nl_recv_msg(struct sk_buff *skb) {

struct nlmsghdr *nlh;
int pid;
struct sk_buff *skb_out;
int msg_size;
char *msg="Hello from kernel";
int res;

printk(KERN_INFO "Entering: %s\n", __FUNCTION__);

msg_size=strlen(msg);

nlh=(struct nlmsghdr*)skb->data;
printk(KERN_INFO "Netlink received msg payload:%s\n",(char*)nlmsg_data(nlh));
pid = nlh->nlmsg_pid; /*pid of sending process */

skb_out = nlmsg_new(msg_size,0);

if(!skb_out)
{

    printk(KERN_ERR "Failed to allocate new skb\n");
    return;

} 
nlh=nlmsg_put(skb_out,0,0,NLMSG_DONE,msg_size,0);  
NETLINK_CB(skb_out).dst_group = 0; /* not in mcast group */
strncpy(nlmsg_data(nlh),msg,msg_size);

res=nlmsg_unicast(nl_sk,skb_out,pid);

if(res<0)
    printk(KERN_INFO "Error while sending bak to user\n");
}

static int __init hello_init(void) {

printk("Entering: %s\n",__FUNCTION__);
/* This is for 3.6 kernels and above.
struct netlink_kernel_cfg cfg = {
    .input = hello_nl_recv_msg,
};

nl_sk = netlink_kernel_create(&init_net, NETLINK_USER, &cfg);*/
nl_sk = netlink_kernel_create(&init_net, NETLINK_USER, 0, hello_nl_recv_msg,NULL,THIS_MODULE);
if(!nl_sk)
{

    printk(KERN_ALERT "Error creating socket.\n");
    return -10;

}

return 0;
}

static void __exit hello_exit(void) {

printk(KERN_INFO "exiting hello module\n");
netlink_kernel_release(nl_sk);
}

module_init(hello_init); module_exit(hello_exit);

MODULE_LICENSE("GPL");

netlinkUser.c

#include <sys/socket.h>
#include <linux/netlink.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#define NETLINK_USER 31

#define MAX_PAYLOAD 1024 /* maximum payload size*/
struct sockaddr_nl src_addr, dest_addr;
struct nlmsghdr *nlh = NULL;
struct iovec iov;
int sock_fd;
struct msghdr msg;

int main()
{
sock_fd=socket(PF_NETLINK, SOCK_RAW, NETLINK_USER);
if(sock_fd<0)
return -1;

memset(&src_addr, 0, sizeof(src_addr));
src_addr.nl_family = AF_NETLINK;
src_addr.nl_pid = getpid(); /* self pid */

bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));

memset(&dest_addr, 0, sizeof(dest_addr));
memset(&dest_addr, 0, sizeof(dest_addr));
dest_addr.nl_family = AF_NETLINK;
dest_addr.nl_pid = 0; /* For Linux Kernel */
dest_addr.nl_groups = 0; /* unicast */

nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));
memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD));
nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
nlh->nlmsg_pid = getpid();
nlh->nlmsg_flags = 0;

strcpy(NLMSG_DATA(nlh), "Hello");

iov.iov_base = (void *)nlh;
iov.iov_len = nlh->nlmsg_len;
msg.msg_name = (void *)&dest_addr;
msg.msg_namelen = sizeof(dest_addr);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;

printf("Sending message to kernel\n");
sendmsg(sock_fd,&msg,0);
printf("Waiting for message from kernel\n");

/* Read message from kernel */
recvmsg(sock_fd, &msg, 0);
printf("Received message payload: %s\n", (char *)NLMSG_DATA(nlh));
close(sock_fd);
}

Makefile文件（用于netlinkKernel.c）

KBUILD_CFLAGS += -w

obj-m += netlinkKernel.o

all:
    make -w -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
// Make sure the indentations before these "make" lines is a tab
clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

只要运行“make”，然后“GCC netlinkUser.c -o netlinkUser”，然后“命令insmod的netlinkKernel.ko”，那么当你运行“./netlinkUser”你应该看到一个消息被发送到内核模块和一个答复由用户空间应用程序接收。在终端中运行“dmesg的”后，你会看到由内核模块打印的调试消息。

如果你有问题了，让我知道，我膝盖深在现在这种权利与我自己的项目。