Re: Bug#304556: file permissions race in mkdir, mknod, mkfifo (CAN-2005-1039)

[Paul Eggert]

My kneejerk reaction is that it's not worth making this change.  The
attack in question will work against almost any program that is
operated in an insecure directory, including the "chmod" program
itself.  It'd be a real pain to work around this problem in all
applications, one at a time, and it's not at all clear to me that it's
even doable in general.

I suggest simply warning users that if you let bad guys modify your
directories, you're asking for trouble.  Which is certainly true in
any event.

That being said, it would be an easy security improvement if mkdir -m
would use lchmod rather than chmod, on platforms where lchmod is
available.  There may be several other programs where this would be
advisable as well, and similarly for lchown versus chown.