lkml.org 
[lkml]   [1999]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: only root has acces to /dev/mem ?
Date
From
Alan Cox wrote:
> > sine i am using 2.2.12 i had no permissions to write on /dev/mem
> > i belong to the group kmem who has +rw on it i cann't write
> > when i chown it the user cann't still write on it
> > only root can??
> > was it a security bug or so??
>
> Tightening rather than anything else. You need the RAWIO capability to use
> /dev/mem or /dev/kmem. You can drop all other capabilities

Huh? Why would you require a capability when normal filesystem
permissions already work? I mean there used to be a whole lot of ioctls
and stuff that required "root", but now require a capability. Good.

So far the capabilities have always been "compatible", people who
don't care needn't care.

Ok, giving someone write access to /dev/mem effectively gives away
root access, but suppose we have a setuid-kmem(*) application that does
something specific with kmem. We don't want it to have filesystem
permissions associated with "root", so we make it setuid-kmem, and
give that user access to /dev/mem.

How do I make an application set-capability-rawio?

Roger.

(*) Or setgid. Whatever.

--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
------ Microsoft SELLS you Windows, Linux GIVES you the whole house ------


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:53    [W:0.046 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site