Re: Linux kernel filesystem oddities

From: Pavel Kankovsky (peakat_private)
Date: Wed Jul 08 1998 - 10:12:20 PDT

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    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."
    



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