Re: securety related question...

On Sun, 6 Oct 2002, Richard Lightman wrote:

> * Bill maltby - LFS Related <[email protected]> [2002-10-06 10:32]:
> > 
> > [...] Further, I do the mount as read only, thereby safegaurding the
> > sources from accidental corruption by any of the root activities
> > inside the $LFS jail. No problem, no noticed performance issues.
> > 
> Could you check that you can bind a rw device ro? I read somewhere
> that there was a patch to keep separate mount flags for each mount,
> but it does not appear to be there yet:

Ahh! Good point! The advantages of interaction continue to amaze me. I
have almost always put my sources on a partition different from the host
partition, for reasons of portability/security. Since it is not normally
mounted when running from the host, I had not thought of that issue.

> [root@urusai root]# mount --version; uname -a
> mount: mount-2.11u
> Linux urusai.localnet.rcl 2.4.20-pre8 #1 Thu Oct 3 07:52:50 BST 2002 i686 unknown
> [root@urusai root]# mount -o ro --bind /tmp /floppy
> [root@urusai root]# ls /tmp
> [root@urusai root]# touch /floppy/x
> [root@urusai root]# ls /tmp
> x
> [root@urusai root]# grep ^tmp /proc/mounts
> tmp /tmp tmpfs rw,nosuid,nodev,noexec 0 0
> tmp /floppy tmpfs rw,nosuid,nodev,noexec 0 0
> [root@urusai root]#

I get the same results with the same version of mount that you have.
Further, if I do a "remount,ro", the remount affects the "base" mount as
well as the bound mount. So, until separate flags for the bound mount
point become available, there is reduced security available for the "host"
partition if it must be mounted rw.

> Richard

-- 
Bill Maltby
[email protected]

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