[PATCH AUTOSEL 4.19 70/97] netfilter: ipt_CLUSTERIP: fix deadlock in netns exit routine

From: Sasha Levin
Date: Tue Jan 08 2019 - 14:50:45 EST

From: Taehee Yoo <ap420073@xxxxxxxxx>

[ Upstream commit 5a86d68bcf02f2d1e9a5897dd482079fd5f75e7f ]

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: 202f59afd441 ("netfilter: ipt_CLUSTERIP: do not hold dev")
Signed-off-by: Taehee Yoo <ap420073@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv4/netfilter/ipt_CLUSTERIP.c | 155 ++++++++++++++++-------------
1 file changed, 87 insertions(+), 68 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 33491cb6b9d1..fb1e7f237f53 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -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)
@@ -181,32 +190,37 @@ 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);
- switch (event) {
- case NETDEV_REGISTER:
- if (!strcmp(dev->name, c->ifname)) {
- c->ifindex = dev->ifindex;
- dev_mc_add(dev, c->clustermac);
- }
- break;
- case NETDEV_UNREGISTER:
- if (dev->ifindex == c->ifindex) {
- dev_mc_del(dev, c->clustermac);
- c->ifindex = -1;
- }
- break;
- case NETDEV_CHANGENAME:
- if (!strcmp(dev->name, c->ifname)) {
- c->ifindex = dev->ifindex;
- dev_mc_add(dev, c->clustermac);
- } else if (dev->ifindex == c->ifindex) {
- dev_mc_del(dev, c->clustermac);
- c->ifindex = -1;
+ 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)) {
+ c->ifindex = dev->ifindex;
+ dev_mc_add(dev, c->clustermac);
+ }
+ break;
+ case NETDEV_UNREGISTER:
+ if (dev->ifindex == c->ifindex) {
+ dev_mc_del(dev, c->clustermac);
+ c->ifindex = -1;
+ }
+ break;
+ case NETDEV_CHANGENAME:
+ if (!strcmp(dev->name, c->ifname)) {
+ c->ifindex = dev->ifindex;
+ dev_mc_add(dev, c->clustermac);
+ } else if (dev->ifindex == c->ifindex) {
+ dev_mc_del(dev, c->clustermac);
+ c->ifindex = -1;
+ }
+ break;
}
- 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;
- }
+ 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);
@@ -503,7 +511,7 @@ 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;
}
@@ -525,7 +533,7 @@ 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);

@@ -807,7 +815,7 @@ 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);
@@ -832,7 +840,7 @@ 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);

--
2.19.1