谁能给我最新的netlink编程示例? [英] Who can give me the latest netlink programming samples?

问题描述

我正在编写一个 Linux 驱动程序，使用 netlink 在用户空间和内核空间之间进行通信.但是我找不到一些有用的材料，因为netlink已经从Linux kernel>=2.6.24改变了.谁能给我一些关于如何创建netlink socket的建议.提前致谢！

I'm writing a Linux driver using netlink to communicate between user space and kernel space. But I can't find some useful materials, because the netlink has changed from Linux kernel >=2.6.24. Who can give me some suggestions about how to create a netlink socket. Thanks in advance!

推荐答案

下面的代码演示了使用 netlink 将数据从用户空间应用程序发送到内核模块的基础知识.此代码在 Linux 2.6.28.9 上使用 libnl 的 git 版本 (ef8ba32).有关更多详细信息，请查看 libnl 文档 和 iw 广泛使用 netlink.

The code below demonstrates the basics of sending data from a user space application to a kernel module using netlink. This code works on Linux 2.6.28.9 with the git version (ef8ba32) of libnl. For more details, check out the libnl documentation and the code for iw which extensively uses netlink.

内核

#include <linux/kernel.h>
#include <linux/module.h>

#include <net/sock.h>
#include <net/netlink.h>

#define MY_MSG_TYPE (0x10 + 2)  // + 2 is arbitrary. same value for kern/usr

static struct sock *my_nl_sock;

DEFINE_MUTEX(my_mutex);

static int
my_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    int type;
    char *data;

    type = nlh->nlmsg_type;
    if (type != MY_MSG_TYPE) {
        printk("%s: expect %#x got %#x
", __func__, MY_MSG_TYPE, type);
        return -EINVAL;
    }

    data = NLMSG_DATA(nlh);
    printk("%s: %02x %02x %02x %02x %02x %02x %02x %02x
", __func__,
            data[0], data[1], data[2], data[3],
            data[4], data[5], data[6], data[7]);
    return 0;
}

static void
my_nl_rcv_msg(struct sk_buff *skb)
{
    mutex_lock(&my_mutex);
    netlink_rcv_skb(skb, &my_rcv_msg);
    mutex_unlock(&my_mutex);
}

static int
my_init(void)
{
    my_nl_sock = netlink_kernel_create(&init_net, NETLINK_USERSOCK, 0,
            my_nl_rcv_msg, NULL, THIS_MODULE);
    if (!my_nl_sock) {
        printk(KERN_ERR "%s: receive handler registration failed
", __func__);
        return -ENOMEM;
    }

    return 0;
}

static void
my_exit(void)
{
    if (my_nl_sock) {
        netlink_kernel_release(my_nl_sock);
    }
}

module_init(my_init);
module_exit(my_exit);

用户空间

#include <stdio.h>
#include <stdlib.h>

#include <netlink/netlink.h>

#define MY_MSG_TYPE (0x10 + 2)  // + 2 is arbitrary but is the same for kern/usr
int
main(int argc, char *argv[])
{
    struct nl_sock *nls;
    char msg[] = { 0xde, 0xad, 0xbe, 0xef, 0x90, 0x0d, 0xbe, 0xef };
    int ret;

    nls = nl_socket_alloc();
    if (!nls) {
        printf("bad nl_socket_alloc
");
        return EXIT_FAILURE;
    }

    ret = nl_connect(nls, NETLINK_USERSOCK);
    if (ret < 0) {
        nl_perror(ret, "nl_connect");
        nl_socket_free(nls);
        return EXIT_FAILURE;
    }

    ret = nl_send_simple(nls, MY_MSG_TYPE, 0, msg, sizeof(msg));
    if (ret < 0) {
        nl_perror(ret, "nl_send_simple");
        nl_close(nls);
        nl_socket_free(nls);
        return EXIT_FAILURE;
    } else {
        printf("sent %d bytes
", ret);
    }

    nl_close(nls);
    nl_socket_free(nls);

    return EXIT_SUCCESS;
}

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