Re: /proc filesystem allows bypassing directory permissions on Linux

[Pavel Machek <pavel@xxxxxx>]

> >Original owner did chmod 666... after making sure traditional unix
> >permissions protect the file. Please look at original mail; it was
> >subtle but I believe I got it right, and file would not be writable
> >with /proc unmounted.
> >
> I remember the original mail content. You're right, you can't reach
> the file if the procfs is not mounted, but you forget about the
> race, allowing the guest to create a hardlink to the file in an
> unrestricted location before the directory access becomes
> restricted. Again, procfs is just another, specific kind of
> hardlinks.

Check it again.  There's no race; I check link count before chmod 666.
                                                                        Pavel
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