Commit 5a86d68b authored by Taehee Yoo's avatar Taehee Yoo Committed by Pablo Neira Ayuso
Browse files

netfilter: ipt_CLUSTERIP: fix deadlock in netns exit routine 



When network namespace is destroyed, cleanup_net() is called.
cleanup_net() holds pernet_ops_rwsem then calls each ->exit callback.
So that clusterip_tg_destroy() is called by cleanup_net().
And clusterip_tg_destroy() calls unregister_netdevice_notifier().

But both cleanup_net() and clusterip_tg_destroy() hold same
lock(pernet_ops_rwsem). hence deadlock occurrs.

After this patch, only 1 notifier is registered when module is inserted.
And all of configs are added to per-net list.

test commands:
   %ip netns add vm1
   %ip netns exec vm1 bash
   %ip link set lo up
   %iptables -A INPUT -p tcp -i lo -d 192.168.0.5 --dport 80 \
	-j CLUSTERIP --new --hashmode sourceip \
	--clustermac 01:00:5e:00:00:20 --total-nodes 2 --local-node 1
   %exit
   %ip netns del vm1

splat looks like:
[  341.809674] ============================================
[  341.809674] WARNING: possible recursive locking detected
[  341.809674] 4.19.0-rc5+ #16 Tainted: G        W
[  341.809674] --------------------------------------------
[  341.809674] kworker/u4:2/87 is trying to acquire lock:
[  341.809674] 000000005da2d519 (pernet_ops_rwsem){++++}, at: unregister_netdevice_notifier+0x8c/0x460
[  341.809674]
[  341.809674] but task is already holding lock:
[  341.809674] 000000005da2d519 (pernet_ops_rwsem){++++}, at: cleanup_net+0x119/0x900
[  341.809674]
[  341.809674] other info that might help us debug this:
[  341.809674]  Possible unsafe locking scenario:
[  341.809674]
[  341.809674]        CPU0
[  341.809674]        ----
[  341.809674]   lock(pernet_ops_rwsem);
[  341.809674]   lock(pernet_ops_rwsem);
[  341.809674]
[  341.809674]  *** DEADLOCK ***
[  341.809674]
[  341.809674]  May be due to missing lock nesting notation
[  341.809674]
[  341.809674] 3 locks held by kworker/u4:2/87:
[  341.809674]  #0: 00000000d9df6c92 ((wq_completion)"%s""netns"){+.+.}, at: process_one_work+0xafe/0x1de0
[  341.809674]  #1: 00000000c2cbcee2 (net_cleanup_work){+.+.}, at: process_one_work+0xb60/0x1de0
[  341.809674]  #2: 000000005da2d519 (pernet_ops_rwsem){++++}, at: cleanup_net+0x119/0x900
[  341.809674]
[  341.809674] stack backtrace:
[  341.809674] CPU: 1 PID: 87 Comm: kworker/u4:2 Tainted: G        W         4.19.0-rc5+ #16
[  341.809674] Workqueue: netns cleanup_net
[  341.809674] Call Trace:
[ ... ]
[  342.070196]  down_write+0x93/0x160
[  342.070196]  ? unregister_netdevice_notifier+0x8c/0x460
[  342.070196]  ? down_read+0x1e0/0x1e0
[  342.070196]  ? sched_clock_cpu+0x126/0x170
[  342.070196]  ? find_held_lock+0x39/0x1c0
[  342.070196]  unregister_netdevice_notifier+0x8c/0x460
[  342.070196]  ? register_netdevice_notifier+0x790/0x790
[  342.070196]  ? __local_bh_enable_ip+0xe9/0x1b0
[  342.070196]  ? __local_bh_enable_ip+0xe9/0x1b0
[  342.070196]  ? clusterip_tg_destroy+0x372/0x650 [ipt_CLUSTERIP]
[  342.070196]  ? trace_hardirqs_on+0x93/0x210
[  342.070196]  ? __bpf_trace_preemptirq_template+0x10/0x10
[  342.070196]  ? clusterip_tg_destroy+0x372/0x650 [ipt_CLUSTERIP]
[  342.123094]  clusterip_tg_destroy+0x3ad/0x650 [ipt_CLUSTERIP]
[  342.123094]  ? clusterip_net_init+0x3d0/0x3d0 [ipt_CLUSTERIP]
[  342.123094]  ? cleanup_match+0x17d/0x200 [ip_tables]
[  342.123094]  ? xt_unregister_table+0x215/0x300 [x_tables]
[  342.123094]  ? kfree+0xe2/0x2a0
[  342.123094]  cleanup_entry+0x1d5/0x2f0 [ip_tables]
[  342.123094]  ? cleanup_match+0x200/0x200 [ip_tables]
[  342.123094]  __ipt_unregister_table+0x9b/0x1a0 [ip_tables]
[  342.123094]  iptable_filter_net_exit+0x43/0x80 [iptable_filter]
[  342.123094]  ops_exit_list.isra.10+0x94/0x140
[  342.123094]  cleanup_net+0x45b/0x900
[ ... ]

Fixes: 202f59af ("netfilter: ipt_CLUSTERIP: do not hold dev")
Signed-off-by: default avatarTaehee Yoo <ap420073@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 241faece

net/ipv4/netfilter/ipt_CLUSTERIP.c

+87 −68
Original line number Diff line number Diff line
@@ -57,17 +57,14 @@ struct clusterip_config { 
	enum clusterip_hashmode hash_mode;	/* which hashing mode */

	u_int32_t hash_initval;			/* hash initialization */

	struct rcu_head rcu;



	struct net *net;			/* netns for pernet list */

	char ifname[IFNAMSIZ];			/* device ifname */

	struct notifier_block notifier;		/* refresh c->ifindex in it */

};



#ifdef CONFIG_PROC_FS

static const struct file_operations clusterip_proc_fops;

#endif



static unsigned int clusterip_net_id __read_mostly;



struct clusterip_net {

	struct list_head configs;

	/* lock protects the configs list */
@@ -78,16 +75,30 @@ struct clusterip_net { 
#endif

};



static unsigned int clusterip_net_id __read_mostly;

static inline struct clusterip_net *clusterip_pernet(struct net *net)

{

	return net_generic(net, clusterip_net_id);

}



static inline void

clusterip_config_get(struct clusterip_config *c)

{

	refcount_inc(&c->refcount);

}





static void clusterip_config_rcu_free(struct rcu_head *head)

{

	kfree(container_of(head, struct clusterip_config, rcu));

	struct clusterip_config *config;

	struct net_device *dev;



	config = container_of(head, struct clusterip_config, rcu);

	dev = dev_get_by_name(config->net, config->ifname);

	if (dev) {

		dev_mc_del(dev, config->clustermac);

		dev_put(dev);

	}

	kfree(config);

}



static inline void
@@ -101,9 +112,9 @@ 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 net *net, struct clusterip_config *c)

clusterip_config_entry_put(struct clusterip_config *c)

{

	struct clusterip_net *cn = net_generic(net, clusterip_net_id);

	struct clusterip_net *cn = clusterip_pernet(c->net);



	local_bh_disable();

	if (refcount_dec_and_lock(&c->entries, &cn->lock)) {
@@ -118,8 +129,6 @@ clusterip_config_entry_put(struct net *net, struct clusterip_config *c) 
		spin_unlock(&cn->lock);

		local_bh_enable();



		unregister_netdevice_notifier(&c->notifier);



		return;

	}

	local_bh_enable();
@@ -129,7 +138,7 @@ static struct clusterip_config * 
__clusterip_config_find(struct net *net, __be32 clusterip)

{

	struct clusterip_config *c;

	struct clusterip_net *cn = net_generic(net, clusterip_net_id);

	struct clusterip_net *cn = clusterip_pernet(net);



	list_for_each_entry_rcu(c, &cn->configs, list) {

		if (c->clusterip == clusterip)
@@ -181,9 +190,12 @@ clusterip_netdev_event(struct notifier_block *this, unsigned long event, 
		       void *ptr)

{

	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

	struct net *net = dev_net(dev);

	struct clusterip_net *cn = clusterip_pernet(net);

	struct clusterip_config *c;



	c = container_of(this, struct clusterip_config, notifier);

	spin_lock_bh(&cn->lock);

	list_for_each_entry_rcu(c, &cn->configs, list) {

		switch (event) {

		case NETDEV_REGISTER:

			if (!strcmp(dev->name, c->ifname)) {
@@ -207,6 +219,8 @@ clusterip_netdev_event(struct notifier_block *this, unsigned long event, 
			}

			break;

		}

	}

	spin_unlock_bh(&cn->lock);



	return NOTIFY_DONE;

}
@@ -215,30 +229,44 @@ static struct clusterip_config * 
clusterip_config_init(struct net *net, const struct ipt_clusterip_tgt_info *i,

		      __be32 ip, const char *iniface)

{

	struct clusterip_net *cn = net_generic(net, clusterip_net_id);

	struct clusterip_net *cn = clusterip_pernet(net);

	struct clusterip_config *c;

	struct net_device *dev;

	int err;



	if (iniface[0] == '\0') {

		pr_info("Please specify an interface name\n");

		return ERR_PTR(-EINVAL);

	}



	c = kzalloc(sizeof(*c), GFP_ATOMIC);

	if (!c)

		return ERR_PTR(-ENOMEM);



	strcpy(c->ifname, iniface);

	c->ifindex = -1;

	c->clusterip = ip;

	dev = dev_get_by_name(net, iniface);

	if (!dev) {

		pr_info("no such interface %s\n", iniface);

		kfree(c);

		return ERR_PTR(-ENOENT);

	}

	c->ifindex = dev->ifindex;

	strcpy(c->ifname, dev->name);

	memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);

	dev_mc_add(dev, c->clustermac);

	dev_put(dev);



	c->clusterip = ip;

	c->num_total_nodes = i->num_total_nodes;

	clusterip_config_init_nodelist(c, i);

	c->hash_mode = i->hash_mode;

	c->hash_initval = i->hash_initval;

	c->net = net;

	refcount_set(&c->refcount, 1);



	spin_lock_bh(&cn->lock);

	if (__clusterip_config_find(net, ip)) {

		spin_unlock_bh(&cn->lock);

		kfree(c);



		return ERR_PTR(-EBUSY);

		err = -EBUSY;

		goto out_config_put;

	}



	list_add_rcu(&c->list, &cn->configs);
@@ -260,22 +288,17 @@ clusterip_config_init(struct net *net, const struct ipt_clusterip_tgt_info *i, 
	}

#endif



	c->notifier.notifier_call = clusterip_netdev_event;

	err = register_netdevice_notifier(&c->notifier);

	if (!err) {

	refcount_set(&c->entries, 1);

	return c;

	}



#ifdef CONFIG_PROC_FS

	proc_remove(c->pde);

err:

#endif

	spin_lock_bh(&cn->lock);

	list_del_rcu(&c->list);

out_config_put:

	spin_unlock_bh(&cn->lock);

	clusterip_config_put(c);



	return ERR_PTR(err);

}
@@ -475,21 +498,6 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) 
				&e->ip.dst.s_addr);

			return -EINVAL;

		} else {

			struct net_device *dev;



			if (e->ip.iniface[0] == '\0') {

				pr_info("Please specify an interface name\n");

				return -EINVAL;

			}



			dev = dev_get_by_name(par->net, e->ip.iniface);

			if (!dev) {

				pr_info("no such interface %s\n",

					e->ip.iniface);

				return -ENOENT;

			}

			dev_put(dev);



			config = clusterip_config_init(par->net, cipinfo,

						       e->ip.dst.s_addr,

						       e->ip.iniface);
@@ -502,7 +510,7 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) 
	if (ret < 0) {

		pr_info("cannot load conntrack support for proto=%u\n",

			par->family);

		clusterip_config_entry_put(par->net, config);

		clusterip_config_entry_put(config);

		clusterip_config_put(config);

		return ret;

	}
@@ -524,7 +532,7 @@ 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(par->net, cipinfo->config);

	clusterip_config_entry_put(cipinfo->config);



	clusterip_config_put(cipinfo->config);
@@ -806,7 +814,7 @@ static const struct file_operations clusterip_proc_fops = { 


static int clusterip_net_init(struct net *net)

{

	struct clusterip_net *cn = net_generic(net, clusterip_net_id);

	struct clusterip_net *cn = clusterip_pernet(net);

	int ret;



	INIT_LIST_HEAD(&cn->configs);
@@ -831,7 +839,7 @@ static int clusterip_net_init(struct net *net) 


static void clusterip_net_exit(struct net *net)

{

	struct clusterip_net *cn = net_generic(net, clusterip_net_id);

	struct clusterip_net *cn = clusterip_pernet(net);

#ifdef CONFIG_PROC_FS

	proc_remove(cn->procdir);

	cn->procdir = NULL;
@@ -847,6 +855,10 @@ static struct pernet_operations clusterip_net_ops = { 
	.size = sizeof(struct clusterip_net),

};



struct notifier_block cip_netdev_notifier = {

	.notifier_call = clusterip_netdev_event

};



static int __init clusterip_tg_init(void)

{

	int ret;
@@ -859,11 +871,17 @@ static int __init clusterip_tg_init(void) 
	if (ret < 0)

		goto cleanup_subsys;



	ret = register_netdevice_notifier(&cip_netdev_notifier);

	if (ret < 0)

		goto unregister_target;



	pr_info("ClusterIP Version %s loaded successfully\n",

		CLUSTERIP_VERSION);



	return 0;



unregister_target:

	xt_unregister_target(&clusterip_tg_reg);

cleanup_subsys:

	unregister_pernet_subsys(&clusterip_net_ops);

	return ret;
@@ -873,6 +891,7 @@ static void __exit clusterip_tg_exit(void) 
{

	pr_info("ClusterIP Version %s unloading\n", CLUSTERIP_VERSION);



	unregister_netdevice_notifier(&cip_netdev_notifier);

	xt_unregister_target(&clusterip_tg_reg);

	unregister_pernet_subsys(&clusterip_net_ops);

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