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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
View file

@ -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 = {

7
net/ipv4/fib_frontend.c
View file

@ -869,19 +869,14 @@ static int nl_fib_lookup_init(struct net *net)
nl_fib_input, NULL, THIS_MODULE);
if (sk == NULL)
return -EAFNOSUPPORT;
/* Don't hold an extra reference on the namespace */
put_net(sk->sk_net);
net->ipv4.fibnl = sk;
return 0;
}
static void nl_fib_lookup_exit(struct net *net)
{
/* At the last minute lie and say this is a socket for the
* initial network namespace. So the socket will be safe to free.
*/
net->ipv4.fibnl->sk_net = get_net(&init_net);
netlink_kernel_release(net->ipv4.fibnl);
net->ipv4.fibnl = NULL;
}
static void fib_disable_ip(struct net_device *dev, int force)

15
net/netlink/af_netlink.c
View file

@ -1396,6 +1396,9 @@ netlink_kernel_create(struct net *net, int unit, unsigned int groups,
}
netlink_table_ungrab();
/* Do not hold an extra referrence to a namespace as this socket is
* internal to a namespace and does not prevent it to stop. */
put_net(net);
return sk;
out_sock_release:
@ -1411,7 +1414,19 @@ netlink_kernel_release(struct sock *sk)
{
if (sk == NULL || sk->sk_socket == NULL)
return;
/*
* Last sock_put should drop referrence to sk->sk_net. It has already
* been dropped in netlink_kernel_create. Taking referrence to stopping
* namespace is not an option.
* Take referrence to a socket to remove it from netlink lookup table
* _alive_ and after that destroy it in the context of init_net.
*/
sock_hold(sk);
sock_release(sk->sk_socket);
sk->sk_net = get_net(&init_net);
sock_put(sk);
}
EXPORT_SYMBOL(netlink_kernel_release);