Re: Linux kernel filesystem oddities

[peak () kerberos troja mff cuni cz (Pavel Kankovsky)]

On Sun, 5 Jul 1998, Michal Zalewski wrote:

> Any amount of data, overriding quotas and kernel resource limits, can be
> stored in root-owned +t directory (like /tmp) - inside... filenames!

Interesting... the same idea popped up in my mind during the weekend.
On the other hand, I am sure this is not Linux specific.

[...]
> Ah, the same problems are with FIFOs created in root-owned dirs, because
> FIFO is not treated as file.
>
> To Alan: You might not argue with me, but I think there's something wrong with
> Linux philosophy, if any user is able to bypass kernel file limits and quotas.

FIFO itself occupies a single inode, no block, therefore charging inode
quota but not block quota is correct.

> But it seems to be hard to fix. FIFO (and maybe other 'non-file' objects) should
> be probably treated as ordinary file when calculating quota.

> But there will be problem with hard-links - creator of this object is...

Hardlink is not a fs object, it is a directory entry.

The world writable directory is a real problem. It is similar to world
writable files: anyone can use them to store data on its owner.

--Pavel Kankovsky aka Peak  [ Boycott Microsoft--http://www.vcnet.com/bms ]
"You can't be truly paranoid unless you're sure they have already got you."