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netns: don't allocate an id for dead netns

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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>
This commit is contained in:
Nicolas Dichtel 2015-04-03 12:02:37 +02:00 committed by David S. Miller
parent 6d458f5b4e
commit 576b7cd2f6
1 changed files with 3 additions and 1 deletions
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4
net/core/net_namespace.c
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@ -198,8 +198,10 @@ static int __peernet2id(struct net *net, struct net *peer, bool alloc)
*/
int peernet2id(struct net *net, struct net *peer)
{
int id = __peernet2id(net, peer, true);
bool alloc = atomic_read(&peer->count) == 0 ? false : true;
int id;
id = __peernet2id(net, peer, alloc);
return id >= 0 ? id : NETNSA_NSID_NOT_ASSIGNED;
}
EXPORT_SYMBOL(peernet2id);