ChrootDirectory on a per key basis

[Chris Wilson]

Hi Damien,

On Fri, 24 Oct 2008, Damien Miller wrote:
> On Fri, 24 Oct 2008, Peter Stuge wrote:
> > Teemu Ikonen wrote:
> > 
> > > or even better, could a 'chrootdir' option be added to the
> > > Authorized keys format?
> > 
> > Yes. I think this will be the easiest to implement. Give it a shot.
> > Infrastructure is in place also for passing a value from options in
> > authorized_keys.
> 
> No, letting users chroot to arbitrary directories introduces
> serious security problems. Think about hard-linking /bin/su into
> a chroot on the same filesystem where an attacker has filled in
> a friendly /etc/passwd.

I thought that the suid bit was a property of the directory entry, not the 
inode? On what platforms is the suid bit a property of the inode, which 
would make this exploit possible?

Cheers, Chris.
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