Is the restricted shell really secure?

[The WITNESS]

	The problem is that "smart" file system checkers (i.e. "fsck") will
also check to make sure that "." points to the current directory and that ".."
points to its parent.  Running fsck on a filesystem with ".."  pointed to "."
will cause everything from that point on to be discarded by fsck.  (It is much
more likely that something damaged the filesystem than that someone unlinked
".." -- so the designers of fsck would have thought.)

	What I'm after is a means of protecting the filesystem without
unlinking or modifying the directory links.  Can anyone help
-- 
		Brandon Allbery: decvax!cwruecmp{!atvax}!bsafw
		  6504 Chestnut Road, Independence, OH 44131

		  Witness, n.  To watch and learn, joyously.