Query regarding kernel modules intercepting system call.

[Aruna Hewapathirane]

Hello Ajinkya,

On Sat, Jul 8, 2017 at 12:14 PM, Greg KH <greg at kroah.com> wrote:

> On Sat, Jul 08, 2017 at 09:38:52PM +0530, Ajinkya Surnis wrote:
> > Actually, this is not a college assignment. I'm a professional software
> > engineer who is completely new to kernel programming.
>

Welcome to the world of kernel hacking and speaking the 'truth' and being
'honest'
does have it's benefits as you will see soon :)


> > I recently gave an interview to one cloud security firm. The interviewer
> gave
> > me this particular assignment, since this kind of functionality is
> needed in
> > their software.
>

Wish you good luck with the job !


> > Now I'm aware that the approach I have (syscall interception) is wrong.
> > But I also need to find out alternate mechanism to achieve my goal.
> > I searched really hard, but got nothing.
>

Go through the link below very carefully, you do not require two modules.
One single module
that intercepts a syscall and does what you have to do.. please do pay
careful attention to the comments
within the code!

https://github.com/jvns/kernel-module-fun/blob/master/rickroll.c


>
> So it's a programming test to get a job?  That's worse than trying to
> cheat on an exam, as it would mean that I pass the test, not you :(
>

Though I agree 110% with gregkh 'I' also have been where Ajinkya is coming
from so many times.
I have been there, done that too many times to walk away now so.. I
understand the man's pain and frustration.
So against my better judgement I have given him something if he studies
carefully will help him to do what its is he must.

>
> good luck!
>
> greg k-h
>
>
Greg, he told us the plain truth and all he wants is some guidance. If I am
out of line you can bust me as usual on IRC ! How is telling the simple and
plain 'truth' equate to 'cheating" ? Duhh...

Good luck, hope this helps - Aruna





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