Lock out root writes on mounted directory?

[Eric "Shubes"]

Darrin Chandler wrote:
> On Fri, Sep 08, 2006 at 07:51:33AM -0700, Eric Shubes wrote:
>> I've created a sandbox for building rpms. It was suggested to me that for 
>> some directories, such as /bin, /lib, /sbin, I could mount them with 
>> ro,bind options instead of coping or hard linking them. What I've 
>> discovered, though, is that the ro mount option does not prohibit root from 
>> modifying a mounted directory. Is there any way to mount a directory such 
>> that root cannot write to it?
> 
> Verify that it's really mounted ro by typing "mount" and seeing the
> options actually used. If it's really read only and root can write to it
> then it sounds broken to me.
> 
Mount says:
/bin on /opt/qtp-sandbox/bin type none (ro,bind)

It allows me to save a file to /opt/qtp-sandbox/bin from root user.

This is CentOS4.3.
-- 
-Eric 'shubes'