Re: Can't hardlink in different dirs. (BUG#826)

Richard Gooch (rgooch@ras.ucalgary.ca)
Sat, 4 Dec 1999 10:16:02 -0700


Alan Curry writes:
> Richard Gooch writes the following:
> >
> >Andrea Arcangeli writes:
> >> On Fri, 3 Dec 1999, Richard Gooch wrote:
> >>
> >> >as well as very very hostile environments.
> >>
> >> It doesn't work at all on environments where if there's an exploited
> >> "quota exceeded" is a major problem.
> >
> >Of course it still works! If you lock up your directories, people
> >can't make hardlinks. Thus no "quota leaks". What part of "lock up
> >your directories" don't you understand?
>
> And what if you want to share your files without opening yourself up
> to quota attacks by people holding your files open and/or linked?
> Have you never heard of $HOME/public_html?

This misses the point. The proposed change would require me to make my
inodes writable by others in order to let them make hard links. That's
much worse than the problem you're concerned about.

If you run an ISP with shell accounts, and you're concerned about
users fouling up others' quotas, set up a simple shell script:
foreach user
find ~user ! -user $user -exec rm -f {} \;

Maybe even a mount option to prevent non-owner linking to inodes would
be acceptable (although I'm not convinced the "problem" is serious
enough to merit this). But the proposal I've been hearing is basically
a forced change for everyone, and that's not on.

Regards,

Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca

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