tree fe04eb71bfe9bd1fdafbe64586f379b989146f6c
parent 6d458f5b4ece8542a5c2281e40008823fec91814
author Nicolas Dichtel <nicolas.dichtel@6wind.com> 1428055357 +0200
committer David S. Miller <davem@davemloft.net> 1428078991 -0400

netns: don't allocate an id for dead netns

First, let's explain the problem.
Suppose you have an ipip interface that stands in the netns foo and its link
part in the netns bar (so the netns bar has an nsid into the netns foo).
Now, you remove the netns bar:
 - the bar nsid into the netns foo is removed
 - the netns exit method of ipip is called, thus our ipip iface is removed:
   => a netlink message is built in the netns foo to advertise this deletion
   => this netlink message requests an nsid for bar, thus a new nsid is
      allocated for bar and never removed.

This patch adds a check in peernet2id() so that an id cannot be allocated for
a netns which is currently destroyed.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>