Exporting sys_call_table for 2.6.11

[Σωτήριο Κοντογιάννη <skontog@xxxxxxxxxx>]

I tried to compile the following example in order to replace __NR_open
syscall for my linux kernel 2.6.11 :
------------------------------------
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/unistd.h> //System calls list


#include <asm/uaccess.h>

#include <linux/moduleparam.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR(" ");

extern void *sys_call_table[];
static int uid;
module_param(uid,int,0644);
MODULE_PARM_DESC(uid,"Enter user id:\n");
//Pointer to original call
static asmlinkage int (*original_call) (const char *,int,int);

asmlinkage int our_sys_open(const char *filename,int flags,int mode)
{
	int i=0;
	char ch;
	if (uid == current->uid) {
		printk(KERN_INFO "Opened file by %d: ",uid);
		do {
			get_user(ch,filename+i);
			i++;
			printk(KERN_INFO "%c",ch);
		} while (ch!=0);
	}
	return original_call(filename,flags,mode);
}

static int __init my_init(void) {
       original_call=sys_call_table[__NR_open];
       sys_call_table[__NR_open] = our_sys_open;
	printk (KERN_INFO "spying ad UID:%d\n",uid);
 return 0;
}

static void __exit my_clean(void) {

	if (sys_call_table[__NR_open] != our_sys_open ) {
		printk (KERN_ALERT "Entering Unstable state\n");
	}
	sys_call_table[__NR_open]=original_call;
}

module_init(my_init);
module_exit(my_clean);
-----------------------------
But when I compile it I get the following message:
  MODPOST
*** Warning: "sys_call_table" [/root/kernel_sko/ex10/as10.ko] undefined!
this is because (I think) sys_call_table[] is not exported by my kernel.
Is there a patch or a way to export sys_call_table[] ?


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