There is an easy solution for this "obvious ¿¿??" fixed problem.
This works fine with Red Hat 8.0 - kernel 2.4.18-14,
the first distribution that not exports system_call anymore.
You can include this function (locate_sys_call_table) in a
kernel module for intercept sys_calls or create
an independent module that all his job will be
re EXPORT_SYMBOL(sys_call_table) to others modules.
....
#include <linux/syscall.h>
#include <asm/unistd.h>
static void **sys_call_table;
//nearest exported symbol to syscalls in my kernel,
//i hope in others kernels too
//but in other form you can look at your kernel sources
extern void *system_utsname;
....
static int locate_sys_call_table(void) {
unsigned long *begin;
int i;
begin=(unsigned long *) &system_utsname;
for (i=0;i<1024;i++) {
if (*(begin+i)==(unsigned long) sys_socketcall) {
sys_call_table=(void *) (begin+i-__NR_socketcall);
//are you sure?
if (sys_call_table[__NR_exit]==(void *) sys_exit) {
printk("success: located sys_call_table: %X\n",(unsigned
int) sys_call_table);
return(1);
}
}
}
return(0);
}
int __init init_exportmodule (void)
{
if (!locate_sys_call_table()) {
// ... cry again and return error
}
//.....sys_call_table[] works now!!
//......do something like export symbol
//.... or intercept any syscall
}
...
that's all.
----- Original Message -----
From: "Anomalous Force" <anomalous_force@yahoo.com>
To: <kernelnewbies@nl.linux.org>
Sent: Sunday, December 22, 2002 8:23 PM
Subject: sys_call_table
> on the website's faq page under the heading
>
> "How do I intercept system calls ?"
>
> the phrase:
>
> Note that Linus removed sys_call_table in 2.5 kernels.
>
> is not correct.
>
>
> =====
> Main Entry: anom·a·lous
> 1 : inconsistent with or deviating from what is usual, normal, or
expected: IRREGULAR, UNUSUAL
> 2 (a) : of uncertain nature or classification (b) : marked by incongruity
or contradiction : PARADOXICAL
> synonym see IRREGULAR
>
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