It's a terrible thing to hold dev in iptables target. When the dev is
being removed, unregister_netdevice has to wait for the dev to become
free. dmesg will keep logging the err:
kernel:unregister_netdevice: waiting for veth0_in to become free. \
Usage count = 1
until iptables rules with this target are removed manually.
The worse thing is when deleting a netns, a virtual nic will be deleted
instead of reset to init_net in default_device_ops exit/exit_batch. As
it is earlier than to flush the iptables rules in iptable_filter_net_ops
exit, unregister_netdevice will block to wait for the nic to become free.
As unregister_netdevice is actually waiting for iptables rules flushing
while iptables rules have to be flushed after unregister_netdevice. This
'dead lock' will cause unregister_netdevice to block there forever. As
the netns is not available to operate at that moment, iptables rules can
not even be flushed manually either.
The reproducer can be:
# ip netns add test
# ip link add veth0_in type veth peer name veth0_out
# ip link set veth0_in netns test
# ip netns exec test ip link set lo up
# ip netns exec test ip link set veth0_in up
# ip netns exec test iptables -I INPUT -d 1.2.3.4 -i veth0_in -j \
CLUSTERIP --new --clustermac 89:d4:47:eb:9a:fa --total-nodes 3 \
--local-node 1 --hashmode sourceip-sourceport
# ip netns del test
This issue can be triggered by all virtual nics with ipt_CLUSTERIP.
This patch is to fix it by not holding dev in ipt_CLUSTERIP, but only
save dev->ifindex instead of dev. When removing the mc from the dev,
it will get dev by c->ifindex through dev_get_by_index.
Note that it doesn't save dev->name but dev->ifindex, as a dev->name
can be changed, it will confuse ipt_CLUSTERIP.
Reported-by: Jianlin Shi <jishi@xxxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/ipv4/netfilter/ipt_CLUSTERIP.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 038f293..d1adb2f 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -47,7 +47,7 @@ struct clusterip_config {
__be32 clusterip; /* the IP address */
u_int8_t clustermac[ETH_ALEN]; /* the MAC address */
- struct net_device *dev; /* device */
+ int ifindex; /* device ifindex */
u_int16_t num_total_nodes; /* total number of nodes */
unsigned long local_nodes; /* node number array */
@@ -98,19 +98,23 @@ clusterip_config_put(struct clusterip_config *c)
* entry(rule) is removed, remove the config from lists, but don't free it
* yet, since proc-files could still be holding references */
static inline void
-clusterip_config_entry_put(struct clusterip_config *c)
+clusterip_config_entry_put(struct net *net, struct clusterip_config *c)
{
- struct net *net = dev_net(c->dev);
struct clusterip_net *cn = net_generic(net, clusterip_net_id);
local_bh_disable();
if (refcount_dec_and_lock(&c->entries, &cn->lock)) {
+ struct net_device *dev;
+
list_del_rcu(&c->list);
spin_unlock(&cn->lock);
local_bh_enable();
- dev_mc_del(c->dev, c->clustermac);
- dev_put(c->dev);
+ dev = dev_get_by_index(net, c->ifindex);
+ if (dev) {
+ dev_mc_del(dev, c->clustermac);
+ dev_put(dev);
+ }
/* In case anyone still accesses the file, the open/close
* functions are also incrementing the refcount on their own,
@@ -182,7 +186,7 @@ clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
if (!c)
return ERR_PTR(-ENOMEM);
- c->dev = dev;
+ c->ifindex = dev->ifindex;
c->clusterip = ip;
memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);
c->num_total_nodes = i->num_total_nodes;
@@ -427,12 +431,14 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
}
config = clusterip_config_init(cipinfo,
- e->ip.dst.s_addr, dev);
+ e->ip.dst.s_addr, dev);
if (IS_ERR(config)) {
dev_put(dev);
return PTR_ERR(config);
}
- dev_mc_add(config->dev, config->clustermac);
+
+ dev_mc_add(dev, config->clustermac);
+ dev_put(dev);
}
}
cipinfo->config = config;
@@ -458,7 +464,7 @@ static void clusterip_tg_destroy(const struct xt_tgdtor_param *par)
/* if no more entries are referencing the config, remove it
* from the list and destroy the proc entry */
- clusterip_config_entry_put(cipinfo->config);
+ clusterip_config_entry_put(par->net, cipinfo->config);
clusterip_config_put(cipinfo->config);
@@ -558,10 +564,9 @@ arp_mangle(void *priv,
* addresses on different interfacs. However, in the CLUSTERIP case
* this wouldn't work, since we didn't subscribe the mcast group on
* other interfaces */
- if (c->dev != state->out) {
- pr_debug("not mangling arp reply on different "
- "interface: cip'%s'-skb'%s'\n",
- c->dev->name, state->out->name);
+ if (c->ifindex != state->out->ifindex) {
+ pr_debug("not mangling arp reply on different interface: cip'%d'-skb'%d'\n",
+ c->ifindex, state->out->ifindex);
clusterip_config_put(c);
return NF_ACCEPT;
}
--
2.1.0
--
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