Socket_Kernel_Module 06-优快云博客

3 利用proc实现内核和应用层交互

Linux中Proc被称为虚拟文件系统，位于/proc中，其实就是内存的内容。可以利用Proc实现内核和应用程序的数据交互。

对内核，要使用特殊的函数创建、删除proc文件，参考下面代码：

3.1内核myProc_test.c代码

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/tcp.h>
#include <linux/ip.h>
#include <linux/proc_fs.h>
#include <net/ip.h>

static struct proc_dir_entry* proc_mtd;
static char szProcBuffer[5000];
static char szTemp1[1000], szTemp2[1000];
extern int iAckCount;
static int iWritingLength;

//相当于每执行#cat /proc/myProc_test 一次，就执行profile_read一次, iAckCount就递增一次

static int procfile_read(char* buffer, char** buffer_location, off_t offset, int buffer_legnth, int zero)
{
int iLen, iReturnLength;
if( offset > 0 ) return 0;
iWritingLength = 0;
sprintk(szTemp1, "iAckCount = %d/n", iAckCount++);
if( (iWritingLength + strlen(szTemp1)) < 5000)
{
strcat(szProcBuffer, szTemp1);
iWritingLength = strlen(szProcBuffer);
}

else

{
szProcBuffer[0] = '/0';
iWritingLength= 0;
}

*buffer_location = szProcBuffer;
iReturnLength = iWritingLength;
iWritingLength = 0;
return iReturnLength;
}

static int procfile_write(struct file* file, const char* buffer, unsigned long count)
{
    iWritingLength = count;
    if(iWritingLength > 5000 ) iWritingLength = 5000;
    if( copy_from_user(szProcBuffer, buffer, iWritingLength))
    {
        return -EFAULT;
    }
    return iWritingLength;

}

int init_hook(void)
{
//create dir /proc/myProc_test
if((proc_mtd = create_proc_entry("myProc_test", 0, 0)))
{

proc_mtd->read_proc = procfile_read;
proc_mtd->write_proc = procfile_write;
printk("myProc: myProc installed/n");
}
return 0;
}

void remove_hook(void)
{
iAckCount = 0;
if( proc_mtd) remove_proc_entry("myProc_test", 0);
printk("myProc: myProc removed/n");
}

MODULE_LICENSE("GPL");

module_init(init_hook);
module_exit(remove_hook);

编译后，insmod加载后，执行

#cat /proc/myProc_test

iAckCount = 0;

#cat /proc/myProc_test

iAckCount = 1;

可以看到，内核的变量在增长

3.2应用层test.c

#include <unistd.h>

#include <pthread.h>

#include <signal.h>

#include <stdio.h>

#include <string.h>

#include <curses.h>

#include <stdlib.h>

int main( int argc, char* argv[])

{

FILE* pf;

if(( pf = fopen("/proc/myProc_test", "wb")) == 0)

{

return -1;

}

char buf[] = ("test --> /proc/myProc_test/n");

int w = fprintf(pf, "%s/n",buf);

fclose(pf);

printf("write: %d/n", w);

return 0;

}

编译后

#./test

#cat /myProc_test

test --> /proc/myProc_test

iAckCount = 2;

可以看到，应用程序的字符串内核中可以调用读取了

3.3内核写入/proc中

将myHook_TCPSYN修改为，写入/proc中，不用重编译内核，直接修改Module代码即可

#define __KERNEL__

#define MODULE

#include <linux/module.h>

#include <linux/skbuff.h>

#include <linux/tcp.h>

#include <linux/ip.h>

#include <linux/proc_fs.h>

#include <net/ip.h>

//big-endian和little-endian转换，big用在网络中，而linux中是little

#define u32toValue(x) ((__u32)( /

(((__u32)(x) & (__u32)0x000000ffUL) << 24) | /

(((__u32)(x) & (__u32)0x0000ff00UL) << 8) | /

(((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | /

(((__u32)(x) & (__u32)0xff000000UL) >> 24) ))

extern int myHook_TCPSYN_count；

extern int (*myHook_TCPSYN)(struct sk_buff*);

//转为可打印地址

static void IpAddressToString(unsigned long i, char* s)

{

unsinged long j1, j2,j3,j4;

j1 = (i & 0x000000FF);

j2 = (i & 0x0000FF00)>>8;

j3 = (i & 0x00FF0000)>>16;

j4 = (i & 0xFF000000)>>24;

sprintf(s, "%u.%u.%u.%u", j4,j3,j2,j1); //注意顺序

}

static struct proc_dir_entry* proc_mtd;
static char szProcBuffer[5000];

static char szTmp[1000];
//相当于每执行#cat /proc/myProc_test 一次，就执行profile_read一次, iAckCount就递增一次

static int profile_read(char* buffer, char** buffer_location, off_t offset, int buffer_legnth, int zero)
{
    int iLen, iReturnLength;
    if( offset > 0 ) return 0;
    *buffer_location = szProcBuffer; //相当于接口参数从全局变量传入值
    iReturnLength = iWritingLength;
    iWritingLength = 0;
    return iReturnLength;
}

//hook函数的实现

int myHook_TCPSYN_impl(struct sk_buff* skb)

{

strcut iphdr* iph;

strcut tcphdr* th;

char szSourceIP[50], szTargetIP[50];

iph = skb->nh.iph;

if( iph->protocol == IPPROTO_TCP) //判断是否是TCP

{

th = skb->h.th;

if( th->syn) //判断是否是SYN包

{