How to run an a.out file in a kernel module

How to run an a.out file in a kernel module

[ranjith kumar]

Hi,

          How to run an a.out file in a kernel module
             I tried to include
                                    system("./a.out");
     in the C file. But I got compilation errors.

Thanks in advance.

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Re: How to run an a.out file in a kernel module

[Jiri Slaby]

ranjith kumar wrote:
> Hi,
> 
>           How to run an a.out file in a kernel module
>              I tried to include
>                                     system("./a.out");
>      in the C file. But I got compilation errors.

And what exactly do you want kernel to do?
If you want to create a process, see module loading procedure from kernel (i.e.
calling modprobe) -- request_module function or calling 'init=' program --
run_init_process.

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E

Re: How to run an a.out file in a kernel module

[Erik Mouw]

On Fri, Oct 27, 2006 at 11:16:11AM +0100, ranjith kumar wrote:
>           How to run an a.out file in a kernel module
>              I tried to include
>                                     system("./a.out");
>      in the C file. But I got compilation errors.

Simple: you don't. There are a bunch of problems over here:

1) The system() call is a userland libc call and doesn't exist in the
   kernel
2) You can't be sure you're in user context
3) You don't know in what filesytem namespace you are

You could use call_usermodehelper() if you really need to call a
usermode helper, but usually it's a sign of bad design if you need to.


Erik

-- 
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands

Re: How to run an a.out file in a kernel module

[ranjith kumar]

Hi,
    1) What is the synatx of call_usermodehelper()
function?
        I found out that it takes 4 arguments. But
what values  we have to pass as argumets.
I did searched in internet. But could not find out.
Sorry to post this question.

2) How to print something  using C code such that it
will be displayed when corresponding a.out file is
called in a kernel module using call_usermodehelper()
function.

Thanks in advance.

--- Erik Mouw <erik@harddisk-recovery.com> wrote:

> On Fri, Oct 27, 2006 at 11:16:11AM +0100, ranjith
> kumar wrote:
> >           How to run an a.out file in a kernel
> module
> >              I tried to include
> >                                    
> system("./a.out");
> >      in the C file. But I got compilation errors.
> 
> Simple: you don't. There are a bunch of problems
> over here:
> 
> 1) The system() call is a userland libc call and
> doesn't exist in the
>    kernel
> 2) You can't be sure you're in user context
> 3) You don't know in what filesytem namespace you
> are
> 
> You could use call_usermodehelper() if you really
> need to call a
> usermode helper, but usually it's a sign of bad
> design if you need to.
> 
> 
> Erik
> 
> -- 
> +-- Erik Mouw -- www.harddisk-recovery.com -- +31 70
> 370 12 90 --
> | Lab address: Delftechpark 26, 2628 XH, Delft, The
> Netherlands
> -
> To unsubscribe from this list: send the line
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Re: How to run an a.out file in a kernel module

[Jiri Slaby]

Do NOT top-post.

ranjith kumar wrote:
> Hi,
>     1) What is the synatx of call_usermodehelper()
> function?
>         I found out that it takes 4 arguments. But
> what values  we have to pass as argumets.
> I did searched in internet. But could not find out.
> Sorry to post this question.

grep -r call_usermodehelper linux/

> 2) How to print something  using C code such that it
> will be displayed when corresponding a.out file is
> called in a kernel module using call_usermodehelper()
> function.

By adding printk to call_usermodehelper?

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E