Linux系统可卸载内核模块完全指南（中） （6）

#define MODULE
#define __KERNEL__
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
extern void* sys_call_table[];
/*如果lock_mod=1 就是允许加载一个模块*/
int lock_mod=0;
int __NR_myexecve;
/*拦截create_module(...)和stat(...)系统调用*/
int (*orig_create_module)(char*, unsigned long);
int (*orig_stat) (const char *, struct old_stat*);
char *strncpy_fromfs(char *dest, const char *src, int n)
{
char *tmp = src;
int compt = 0;
do {
dest[compt++] = __get_user(tmp++, 1);
}
while ((dest[compt - 1] != '\0') && (compt != n));
return dest;
}
int hacked_stat(const char *filename, struct old_stat *buf)
{
char *name;
int ret;
char *password = "password";
/*yeah,一个很好的密码*/
name　　= (char *) kmalloc(255, GFP_KERNEL);
(void) strncpy_fromfs(name, filename, 255);
/*有密码么?*/
if (strstr(name, password)!=NULL)
{
/*一次仅允许加载一个模块*/
lock_mod=1;
kfree(name);
return 0;
}
else
{
kfree(name);
ret = orig_stat(filename, buf);
}
return ret;
}
int hacked_create_module(char *name, unsigned long size)
{
char *kernel_name;
char hide[]="ourtool";
int ret;
if (lock_mod==1)
{
lock_mod=0;
ret=orig_create_module(name, size);
return ret;
}
else
{
printk("<1>MOD-POL : Permission denied !\n");
return 0;
}
return ret;
}
int init_module(void)
/*初始化模块*/
{
__NR_myexecve = 200;
while (__NR_myexecve != 0 && sys_call_table[__NR_myexecve] != 0)
__NR_myexecve--;
sys_call_table[__NR_myexecve]=sys_call_table[SYS_execve];
orig_stat=sys_call_table[SYS_prev_stat];
sys_call_table[SYS_prev_stat]=hacked_stat;
orig_create_module=sys_call_table[SYS_create_module];
sys_call_table[SYS_create_module]=hacked_create_module;
printk("<1>MOD-POL LOADED...\n");
return 0;
}
void cleanup_module(void)
/*卸载模块*/
{
sys_call_table[SYS_prev_stat]=orig_stat;
sys_call_table[SYS_create_module]=orig_create_module;
}