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[NETNS]: Namespace stop vs 'ip r l' race.

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During network namespace stop process kernel side netlink sockets
belonging to a namespace should be closed. They should not prevent
namespace to stop, so they do not increment namespace usage
counter. Though this counter will be put during last sock_put.

The raplacement of the correct netns for init_ns solves the problem
only partial as socket to be stoped until proper stop is a valid
netlink kernel socket and can be looked up by the user processes. This
is not a problem until it resides in initial namespace (no processes
inside this net), but this is not true for init_net.

So, hold the referrence for a socket, remove it from lookup tables and
only after that change namespace and perform a last put.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Tested-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Denis V. Lunev
2008-01-18 23:55:19 -08:00
committed by David S. Miller
parent b7c6ba6eb1
commit 775516bfa2
3 changed files with 18 additions and 19 deletions
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15
net/core/rtnetlink.c
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@@ -1368,25 +1368,14 @@ static int rtnetlink_net_init(struct net *net)
rtnetlink_rcv, &rtnl_mutex, THIS_MODULE);
if (!sk)
return -ENOMEM;
/* Don't hold an extra reference on the namespace */
put_net(sk->sk_net);
net->rtnl = sk;
return 0;
}
static void rtnetlink_net_exit(struct net *net)
{
struct sock *sk = net->rtnl;
if (sk) {
/* At the last minute lie and say this is a socket for the
* initial network namespace. So the socket will be safe to
* free.
*/
sk->sk_net = get_net(&init_net);
netlink_kernel_release(net->rtnl);
net->rtnl = NULL;
}
netlink_kernel_release(net->rtnl);
net->rtnl = NULL;
}
static struct pernet_operations rtnetlink_net_ops = {