This function reacquires the rtnl_lock() which is already held by
nf_unregister_hook().
This can be triggered via: modprobe nf_conntrack_ipv4 && rmmod nf_conntrack_ipv4
[ 720.628746] INFO: task rmmod:3578 blocked for more than 120 seconds.
[ 720.628749] Not tainted 4.2.0-rc2+ #113
[ 720.628752] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 720.628754] rmmod D ffff8800ca46fd58 0 3578 3571 0x00000080
[...]
[ 720.628783] Call Trace:
[ 720.628790] [<ffffffff8152ea0b>] schedule+0x6b/0x90
[ 720.628795] [<ffffffff8152ecb3>] schedule_preempt_disabled+0x13/0x20
[ 720.628799] [<ffffffff8152ff55>] mutex_lock_nested+0x1f5/0x380
[ 720.628803] [<ffffffff81462622>] ? rtnl_lock+0x12/0x20
[ 720.628807] [<ffffffff81462622>] ? rtnl_lock+0x12/0x20
[ 720.628812] [<ffffffff81462622>] rtnl_lock+0x12/0x20
[ 720.628817] [<ffffffff8148ab25>] nf_queue_nf_hook_drop+0x15/0x160
[ 720.628825] [<ffffffff81488d48>] nf_unregister_net_hook+0x168/0x190
[ 720.628831] [<ffffffff81488e24>] nf_unregister_hook+0x64/0x80
[ 720.628837] [<ffffffff81488e60>] nf_unregister_hooks+0x20/0x30
[...]
Moreover, nf_unregister_net_hook() should only destroy the queue for this
netns, not for every netns.
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Fixes: 085db2c04557 ("netfilter: Per network namespace netfilter hooks.")
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
This is basically a v2 from http://patchwork.ozlabs.org/patch/497635/.
net/netfilter/core.c | 2 +-
net/netfilter/nf_internals.h | 2 +-
net/netfilter/nf_queue.c | 12 +++---------
3 files changed, 5 insertions(+), 11 deletions(-)
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 87d237d..12504fbb 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -154,7 +154,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
synchronize_net();
- nf_queue_nf_hook_drop(elem);
+ nf_queue_nf_hook_drop(net, elem);
kfree(elem);
}
EXPORT_SYMBOL(nf_unregister_net_hook);
diff --git a/net/netfilter/nf_internals.h b/net/netfilter/nf_internals.h
index 3992106..0655225 100644
--- a/net/netfilter/nf_internals.h
+++ b/net/netfilter/nf_internals.h
@@ -19,7 +19,7 @@ unsigned int nf_iterate(struct list_head *head, struct sk_buff *skb,
/* nf_queue.c */
int nf_queue(struct sk_buff *skb, struct nf_hook_ops *elem,
struct nf_hook_state *state, unsigned int queuenum);
-void nf_queue_nf_hook_drop(struct nf_hook_ops *ops);
+void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops);
int __init netfilter_queue_init(void);
/* nf_log.c */
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 8a8b2ab..96777f9 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -105,21 +105,15 @@ bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
}
EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
-void nf_queue_nf_hook_drop(struct nf_hook_ops *ops)
+void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops)
{
const struct nf_queue_handler *qh;
- struct net *net;
- rtnl_lock();
rcu_read_lock();
qh = rcu_dereference(queue_handler);
- if (qh) {
- for_each_net(net) {
- qh->nf_hook_drop(net, ops);
- }
- }
+ if (qh)
+ qh->nf_hook_drop(net, ops);
rcu_read_unlock();
- rtnl_unlock();
}
/*
--
1.7.10.4
--
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