Re: security patch

["linux-os \(Dick Johnson\)" <linux-os@analogic.com>]

On Thu, 22 Sep 2005 breno@kalangolinux.org wrote:

> Hi people,
>
> I'm doing a new feature for linux kernel 2.6 to protect against all kinds of buffer
> overflow. It works with new sys_control() system call controling if a process can or can't
> call a system call ie. sys_execve();
>

Are you aware that there are very few 'built-in' commands in
any of the shells?  If a user can't execute anything, the
user can't do anything.

If you think that this will protect against improperly-written
daemons, and things that never exec anything, you are wrong.
The place to fix bad code is in the code.

> You can do it using /bin/sys_control <pid> <enable or not system call>
> <eax of system call> <secret number>


This is a joke, right?


> for process that never call for example sys_execve(), setuid()
> ( you must need specify each eax for each system call) and use
> some functions in sys_control.h like lock_execve(n)
> and unlock_execve(n), where n is a secret number defined in sysctl.
> With this functions you will use system calls only when you need.
> All shellcodes that use system calls like sys_execve() sys_setuid()
> will not work with this feature.

What will they do? I try to execute `ls`, the kernel says I can't
fork and exec `/bin/ls`. So, do I get killed, logged out? The
shells handle errors in different ways. There is a big difference
between how bash handles ENOENT (No such file or directory) and
ENOSYS (Function not implimented).

>
> I think it can be an option in linux kernel.
>
> Questions .. suggestions.
>
> Thanks
>

I think this is just another ruse to attempt to get the system
call table exported, something you don't need to do in order
to replace any of its elements. Am I guessing correctly?

> Breno at kalangolinux.org
>

Cheers,
Dick Johnson
Penguin : Linux version 2.6.13 on an i686 machine (5589.55 BogoMips).
Warning : 98.36% of all statistics are fiction.

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