I think is something with my kernel,or with this Fedora ...somebody talled me,i quote "FC is the end of life!"
It's exactly your code:
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/syscalls.h>
#include <sys/syscall.h>
#include <asm/cacheflush.h>
unsigned long **sys_call_table = NULL;
typedef asmlinkage long (*my_unlink_type) (const char __user *);
static my_unlink_type sys_unlink_orig = NULL;
asmlinkage static long my_sys_unlink(const char __user * filename)
{
return sys_unlink_orig(filename);
}
struct _idt {
unsigned short offset_low, segment_sel;
unsigned char reserved, flags;
unsigned short offset_high;
} __attribute__ ((packed));
static void get_system_call_table(void)
{
unsigned char idtr[6], *shell, *sort;
struct _idt *idt;
struct page *sys_call_table_page;
pgprot_t prot;
unsigned long system_call;
unsigned short offset_low, offset_high;
int i;
char *p;
__asm__ __volatile__("sidt %0":"=m"(idtr)::"memory");
idt = (struct _idt *)(*(unsigned long *)&idtr[2] + 8 * 0x80);
offset_low = idt->offset_low;
offset_high = idt->offset_high;
system_call = (offset_high << 16) | offset_low;
/*
* We often place the function 'system_call' address in IDT.
* while machine code \xff\x14\85 stands for anything like
* call offset<,eax,4> offen steps. It is really what we want.
*/
shell = (char *)system_call;
sort = "\xff\x14\x85";
for (i = 0; i < (100 - 2); i++) {
if (shell[i] == sort[0] && shell[i + 1] == sort[1] &&
shell[i + 2] == sort[2])
break;
}
p = (char *)&shell[i + 3];
sys_call_table = (unsigned long **)*(unsigned long *)p;
sys_call_table_page = virt_to_page(sys_call_table);
prot.pgprot = VM_READ | VM_WRITE | VM_EXEC;
change_page_attr(sys_call_table_page, 1, prot);
}
static int my_module_init(void)
{
get_system_call_table();
sys_unlink_orig = (my_unlink_type) sys_call_table[SYS_unlink];
sys_call_table[SYS_unlink] = (unsigned long *)my_sys_unlink;
return 0;
}
static void my_module_exit(void)
{
sys_call_table[SYS_unlink] = (unsigned long *)sys_unlink_orig;
return;
}
module_init(my_module_init);
module_exit(my_module_exit);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Ying Chu,xjtuychu@gmail.com");
MODULE_DESCRIPTION("System Calls hack in kernel 2.6 use IDT vector 128.");
