Linux 内核模块实现udp发送字符串

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Linux 内核模块实现udp发送字符串

2019-07-13 09:07发布生成海报

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From: http://blog.chinaunix.net/uid-20662820-id-3784251.html
昨天CU论坛有人问到如何在内核模块发送数据包，于是找到了之前写的代码，跟大家分享一下。
该代码SLES 11 sp2内核3.0.13上编译运行通过。
点击(此处)折叠或打开

/*
* Kernel Send Udp packet Module
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright(C) Tony <tingw.liu@gmail.com> 2007-2013
*
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/net.h>
#include <linux/inetdevice.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <asm/unaligned.h>
#include <linux/kthread.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tony ");
char *ifname = "eth0";
module_param(ifname, charp, 0644);
MODULE_PARM_DESC(ifname, "Send packets from which net device");
char *buffer = "Tony test from kernel! ";
module_param(buffer, charp, 0644);
MODULE_PARM_DESC(buffer, "Packet content");
__u32 dstip = 0xc0a80056;
module_param(dstip, uint, 0644);
__s16 dstport = 8000;
module_param(dstport, short, 0644);
long timeout = 1;
module_param(timeout, long, 0644);
MODULE_PARM_DESC(timeout, "Interval between send packets, default 1(unit second)");
static struct task_struct *kthreadtask = NULL;
static int bind_to_device(struct socket *sock, char *ifname)
{
struct net *net;
struct net_device *dev;
__be32 addr;
struct sockaddr_in sin;
int err;
net = sock_net(sock->sk);
dev = __dev_get_by_name(net, ifname);
if (!dev) {
printk(KERN_ALERT "No such device named %s ", ifname);
return -ENODEV;
}
addr = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = addr;
sin.sin_port = 0;
err = sock->ops->bind(sock, (struct sockaddr*)&sin, sizeof(sin));
if (err < 0) {
printk(KERN_ALERT "sock bind err, err=%d ", err);
return err;
}
return 0;
}
static int connect_to_addr(struct socket *sock)
{
struct sockaddr_in daddr;
int err;
daddr.sin_family = AF_INET;
daddr.sin_addr.s_addr = cpu_to_be32(dstip);
daddr.sin_port = cpu_to_be16(dstport);
err = sock->ops->connect(sock, (struct sockaddr*)&daddr,
sizeof(struct sockaddr), 0);
if (err < 0) {
printk(KERN_ALERT "sock connect err, err=%d ", err);
return err;
}
return 0;
}
struct threadinfo{
struct socket *sock;
char *buffer;
};
static int sendthread(void *data)
{
struct kvec iov;
struct threadinfo *tinfo = data;
struct msghdr msg = {.msg_flags = MSG_DONTWAIT|MSG_NOSIGNAL};
int len;
while (!kthread_should_stop()) {
iov.iov_base = (void *)tinfo->buffer;
iov.iov_len = strlen(tinfo->buffer);
len = kernel_sendmsg(tinfo->sock, &msg, &iov, 1, strlen(tinfo->buffer));
if (len != strlen(buffer)) {
printk(KERN_ALERT "kernel_sendmsg err, len=%d, buffer=%d ",
len, (int)strlen(buffer));
if (len == -ECONNREFUSED) {
printk(KERN_ALERT "Receive Port Unreachable packet! ");
}
break;
}
schedule_timeout_interruptible(timeout * HZ);
}
kthreadtask = NULL;
sk_release_kernel(tinfo->sock->sk);
kfree(tinfo);
return 0;
}
static int __init udp_send_init(void)
{
int err = 0;
struct socket *sock;
struct threadinfo *tinfo;
err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock);
if (err < 0) {
printk(KERN_ALERT "UDP create sock err, err=%d ", err);
goto create_error;
}
sock->sk->sk_reuse = 1;
err = bind_to_device(sock, ifname);
if (err < 0) {
printk(KERN_ALERT "Bind to %s err, err=%d ", ifname, err);
goto bind_error;
}
err = connect_to_addr(sock);
if (err < 0) {
printk(KERN_ALERT "sock connect err, err=%d ", err);
goto connect_error;
}
tinfo = kmalloc(sizeof(struct threadinfo), GFP_KERNEL);
if (!tinfo) {
printk(KERN_ALERT "kmalloc threadinfo err ");
goto kmalloc_error;
}
tinfo->sock = sock;
tinfo->buffer = buffer;
kthreadtask = kthread_run(sendthread, tinfo, "Tony-sendmsg");
if (IS_ERR(kthreadtask)) {
printk(KERN_ALERT "create sendmsg thread err, err=%ld ",
PTR_ERR(kthreadtask));
goto thread_error;
}
return 0;
thread_error:
kfree(tinfo);
kmalloc_error:
bind_error:
connect_error:
sk_release_kernel(sock->sk);
kthreadtask = NULL;
create_error:
return -1;
}
static void __exit udp_send_exit(void)
{
if (kthreadtask) {
kthread_stop(kthreadtask);
}
printk(KERN_ALERT "UDP send quit ");
return;
}
module_init(udp_send_init);
module_exit(udp_send_exit);