Query regarding kernel modules intercepting system call.

[Ajinkya Surnis]

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).

On Sat, Jul 8, 2017 at 8:50 PM, Greg KH <greg at kroah.com> wrote:

> On Sat, Jul 08, 2017 at 07:53:31PM +0530, Ajinkya Surnis wrote:
> > Actually, I've been given an assignment to write a kernel module such
> that
> > whenever a certain system call (e.g. open()) is executed, the control
> should
> > come to my new module; then it will do some processing on the parameters
> and
> > then call the actual syscall function (sys_open()).
>
> Horrible assignment, please pass along my regards to the professor that
> this is not anything that should ever be assigned.  Seriously, do you
> want me to email them this?
>
> > I only found the way of intercepting 'sys_call_table'. I know this kind
> of
> > hacking is probably not a good idea.
> > Can you suggest any alternative way?
> > I would really appreciate.
>
> Don't do it.
>
> Really, this is not a valid thing to do in Linux.
>
> Feel free to quote me.
>
> Also, the assignment said nothing about 2 modules, so are you sure you
> are even doing this right?  :)
>
> thanks,
>
> greg k-h
>
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