Home/ Questions/Q 499101
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-13T05:57:04+00:00

I am trying to set the sys exit call to a variable by extern

  • 0

I am trying to set the sys exit call to a variable by

extern void *sys_call_table[];
real_sys_exit = sys_call_table[__NR_exit]

however, when I try to make, the console gives me the error

error: ‘__NR_exit’ undeclared (first use in this function)

Any tips would be appreciated 🙂 Thank you

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Since you are in kernel 2.6.x , sys_call_table isnt exported any more.
    If you want to avoid the compilation error try this include

    #include<linux/unistd.h>

    however, It will not work. So the work around to “play” with the sys_call_table is to find the address of sys_call_table in SystemXXXX.map (located at /boot) with this command:

    grep sys_call System.map-2.6.X -i

    this will give the addres, then this code should allow you to modify the table:

    unsigned long *sys_call_table; 
sys_call_table = (unsigned long *) simple_strtoul("0xc0318500",NULL,16); 


original_mkdir = sys_call_table[__NR_mkdir];
sys_call_table[__NR_mkdir] = mkdir_modificado;

    Hope it works for you, I have just tested it under kernel 2.6.24, so should work for 2.6.18

    also check here, Its a very good
    http://commons.oreilly.com/wiki/index.php/Network_Security_Tools/Modifying_and_Hacking_Security_Tools/Fun_with_Linux_Kernel_Modules

    • 0