netns : close all sockets at unshare ?

[Daniel Lezcano <dlezcano-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>]

Hi,

I was looking at some cornercases and trying to figure out what happens 
if someone does:

1 - fd = socket(...)
2 - unshare(CLONE_NEWNET)
3 - bind(fd, ...) / listen(fd, ...)

There is here an interaction between two namespaces.
Trying to catch all these little tricky paths everywhere with the 
network namespace is painful, perhaps we should consider a more radical 
solution.

Shall we close all fd sockets when doing an unshare ? like a 
close-on-exec behavior ?