Query regarding kernel modules intercepting system call.

[Ajinkya Surnis]

Actually, this is not a college assignment. I'm a professional software
engineer who is completely new to kernel programming.
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.
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.

Thanks,
Ajinkya.

On Sat, Jul 8, 2017 at 9:34 PM, Greg KH <greg at kroah.com> wrote:

> On Sat, Jul 08, 2017 at 09:08:40PM +0530, Ajinkya Surnis wrote:
> > The purpose of assignment is to check the authenticity of the user
> executing
> > the system call, and prevent certain users from executing, kind of like
> certain
> > security programs (although I don't exactly know how they work).
>
> Then that's a totally different thing.
>
> Don't hook a syscall for this at all.
>
> There is a better way, and a correct one, but as this is a homework
> assignment, and I'm not the one getting credit for the assignment, I'm
> not going to spell it out how to do it, sorry.  Otherwise you would get
> in trouble.
>
> Actually, are you sure you are allowed to ask for help for your
> assignment from others in the first place?  Most schools have rules
> about stuff like this...
>
> greg k-h
>
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