The statement taken by itself is incorrect, but the actual feature that has been in grsecurity for over 9 years and Openwall even longer than that also adds hardlink restrictions that prevent exactly your attack.
Posted Jun 3, 2010 12:41 UTC (Thu) by mikachu (guest, #5333)
[Link]
Are those restrictions also part of the patches proposed for mainline?
Symbolic links in "sticky" directories
Posted Jun 3, 2010 23:08 UTC (Thu) by kees (subscriber, #27264)
[Link]
Ubuntu is carrying the hardlink restrictions as well. I intend to upstream it too, but I'm trying to do one thing at a time; they are different -- but obviously related -- topics.