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authorDenis V. Lunev <den@openvz.org>2008-01-18 23:55:19 -0800
committerDavid S. Miller <davem@davemloft.net>2008-01-28 15:08:08 -0800
commit775516bfa2bd7993620c9039191a0c30b8d8a496 (patch)
tree7385f35edda9f4124b802ccf337c55070d2e00bc
parentb7c6ba6eb1234e35a74fb8ba8123232a7b1ba9e4 (diff)
[NETNS]: Namespace stop vs 'ip r l' race.
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>
-rw-r--r--net/core/rtnetlink.c15
-rw-r--r--net/ipv4/fib_frontend.c7
-rw-r--r--net/netlink/af_netlink.c15
3 files changed, 18 insertions, 19 deletions
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 02cf848f71d..ddbdde82a70 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -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 = {
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index e787d215115..62bd791c204 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -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)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 626a5820629..6b178e1247b 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -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);