[$] Restricting path name lookup with openat2()

Looking up a file given a path name seems like a straightforward task, but
it turns out to be one of the more complex things the kernel does. Things
get more complicated if one is trying to write robust (user-space) code
that can do the right thing with paths that are controlled by a potentially
hostile user. Attempts to make the , but
numerous problems remain. Aleksa Sarai, who has ,
is required to truly solve this problem.