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Date: Fri, 13 May 2016 15:44:38 -0500
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Florian Westphal <fw@...len.de>
Cc: Pablo Neira Ayuso <pablo@...filter.org>,
netfilter-devel@...r.kernel.org, dale.4d@...il.com,
netdev@...r.kernel.org
Subject: Re: [PATCH nf V2] netfilter: fix oops in nfqueue during netns error unwinding
Florian could you test and verify this patch fixes your issues?
Unlike the other possibilities that have been discussed this also
addresses the nf_queue path as well as the nf_queue_hook_drop path.
And frankly that is the best argument I have for fixing it this way
because potentially nf_queue could have similar issues.
Eric
From: "Eric W. Biederman" <ebiederm@...ssion.com>
Date: Fri, 13 May 2016 15:26:03 -0500
Subject: [PATCH] nf_queue: Make the queue_handler pernet
Florian Weber reported:
> Under full load (unshare() in loop -> OOM conditions) we can
> get kernel panic:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> IP: [<ffffffff81476c85>] nfqnl_nf_hook_drop+0x35/0x70
> [..]
> task: ffff88012dfa3840 ti: ffff88012dffc000 task.ti: ffff88012dffc000
> RIP: 0010:[<ffffffff81476c85>] [<ffffffff81476c85>] nfqnl_nf_hook_drop+0x35/0x70
> RSP: 0000:ffff88012dfffd80 EFLAGS: 00010206
> RAX: 0000000000000008 RBX: ffffffff81add0c0 RCX: ffff88013fd80000
> [..]
> Call Trace:
> [<ffffffff81474d98>] nf_queue_nf_hook_drop+0x18/0x20
> [<ffffffff814738eb>] nf_unregister_net_hook+0xdb/0x150
> [<ffffffff8147398f>] netfilter_net_exit+0x2f/0x60
> [<ffffffff8141b088>] ops_exit_list.isra.4+0x38/0x60
> [<ffffffff8141b652>] setup_net+0xc2/0x120
> [<ffffffff8141bd09>] copy_net_ns+0x79/0x120
> [<ffffffff8106965b>] create_new_namespaces+0x11b/0x1e0
> [<ffffffff810698a7>] unshare_nsproxy_namespaces+0x57/0xa0
> [<ffffffff8104baa2>] SyS_unshare+0x1b2/0x340
> [<ffffffff81608276>] entry_SYSCALL_64_fastpath+0x1e/0xa8
> Code: 65 00 48 89 e5 41 56 41 55 41 54 53 83 e8 01 48 8b 97 70 12 00 00 48 98 49 89 f4 4c 8b 74 c2 18 4d 8d 6e 08 49 81 c6 88 00 00 00 <49> 8b 5d 00 48 85 db 74 1a 48 89 df 4c 89 e2 48 c7 c6 90 68 47
>
The simple fix for this requires a new pernet variable for struct
nf_queue that indicates when it is safe to use the dynamically
allocated nf_queue state.
As we need a variable anyway make nf_register_queue_handler and
nf_unregister_queue_handler pernet. This allows the existing logic of
when it is safe to use the state from the nfnetlink_queue module to be
reused with no changes except for making it per net.
The syncrhonize_rcu from nf_unregister_queue_handler is moved to a new
function nfnl_queue_net_exit_batch so that the worst case of having a
syncrhonize_rcu in the pernet exit path is not experienced in batch
mode.
Reported-by: Florian Westphal <fw@...len.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
include/net/netfilter/nf_queue.h | 4 ++--
include/net/netns/netfilter.h | 2 ++
net/netfilter/nf_queue.c | 17 ++++++++---------
net/netfilter/nfnetlink_queue.c | 18 ++++++++++++------
4 files changed, 24 insertions(+), 17 deletions(-)
diff --git a/include/net/netfilter/nf_queue.h b/include/net/netfilter/nf_queue.h
index 9c5638ad872e..0dbce55437f2 100644
--- a/include/net/netfilter/nf_queue.h
+++ b/include/net/netfilter/nf_queue.h
@@ -28,8 +28,8 @@ struct nf_queue_handler {
struct nf_hook_ops *ops);
};
-void nf_register_queue_handler(const struct nf_queue_handler *qh);
-void nf_unregister_queue_handler(void);
+void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh);
+void nf_unregister_queue_handler(struct net *net);
void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
void nf_queue_entry_get_refs(struct nf_queue_entry *entry);
diff --git a/include/net/netns/netfilter.h b/include/net/netns/netfilter.h
index 38aa4983e2a9..36d723579af2 100644
--- a/include/net/netns/netfilter.h
+++ b/include/net/netns/netfilter.h
@@ -5,11 +5,13 @@
struct proc_dir_entry;
struct nf_logger;
+struct nf_queue_handler;
struct netns_nf {
#if defined CONFIG_PROC_FS
struct proc_dir_entry *proc_netfilter;
#endif
+ const struct nf_queue_handler __rcu *queue_handler;
const struct nf_logger __rcu *nf_loggers[NFPROTO_NUMPROTO];
#ifdef CONFIG_SYSCTL
struct ctl_table_header *nf_log_dir_header;
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 5baa8e24e6ac..b19ad20a705c 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -26,23 +26,21 @@
* Once the queue is registered it must reinject all packets it
* receives, no matter what.
*/
-static const struct nf_queue_handler __rcu *queue_handler __read_mostly;
/* return EBUSY when somebody else is registered, return EEXIST if the
* same handler is registered, return 0 in case of success. */
-void nf_register_queue_handler(const struct nf_queue_handler *qh)
+void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh)
{
/* should never happen, we only have one queueing backend in kernel */
- WARN_ON(rcu_access_pointer(queue_handler));
- rcu_assign_pointer(queue_handler, qh);
+ WARN_ON(rcu_access_pointer(net->nf.queue_handler));
+ rcu_assign_pointer(net->nf.queue_handler, qh);
}
EXPORT_SYMBOL(nf_register_queue_handler);
/* The caller must flush their queue before this */
-void nf_unregister_queue_handler(void)
+void nf_unregister_queue_handler(struct net *net)
{
- RCU_INIT_POINTER(queue_handler, NULL);
- synchronize_rcu();
+ RCU_INIT_POINTER(net->nf.queue_handler, NULL);
}
EXPORT_SYMBOL(nf_unregister_queue_handler);
@@ -103,7 +101,7 @@ void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops)
const struct nf_queue_handler *qh;
rcu_read_lock();
- qh = rcu_dereference(queue_handler);
+ qh = rcu_dereference(net->nf.queue_handler);
if (qh)
qh->nf_hook_drop(net, ops);
rcu_read_unlock();
@@ -122,9 +120,10 @@ int nf_queue(struct sk_buff *skb,
struct nf_queue_entry *entry = NULL;
const struct nf_afinfo *afinfo;
const struct nf_queue_handler *qh;
+ struct net *net = state->net;
/* QUEUE == DROP if no one is waiting, to be safe. */
- qh = rcu_dereference(queue_handler);
+ qh = rcu_dereference(net->nf.queue_handler);
if (!qh) {
status = -ESRCH;
goto err;
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index cb5b630a645b..2c13e41c508c 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -1377,21 +1377,29 @@ static int __net_init nfnl_queue_net_init(struct net *net)
net->nf.proc_netfilter, &nfqnl_file_ops))
return -ENOMEM;
#endif
+ nf_register_queue_handler(net, &nfqh);
return 0;
}
static void __net_exit nfnl_queue_net_exit(struct net *net)
{
+ nf_unregister_queue_handler(net);
#ifdef CONFIG_PROC_FS
remove_proc_entry("nfnetlink_queue", net->nf.proc_netfilter);
#endif
}
+static void nfnl_queue_net_exit_batch(struct list_head *net_exit_list)
+{
+ synchronize_rcu();
+}
+
static struct pernet_operations nfnl_queue_net_ops = {
- .init = nfnl_queue_net_init,
- .exit = nfnl_queue_net_exit,
- .id = &nfnl_queue_net_id,
- .size = sizeof(struct nfnl_queue_net),
+ .init = nfnl_queue_net_init,
+ .exit = nfnl_queue_net_exit,
+ .exit_batch = nfnl_queue_net_exit_batch,
+ .id = &nfnl_queue_net_id,
+ .size = sizeof(struct nfnl_queue_net),
};
static int __init nfnetlink_queue_init(void)
@@ -1412,7 +1420,6 @@ static int __init nfnetlink_queue_init(void)
}
register_netdevice_notifier(&nfqnl_dev_notifier);
- nf_register_queue_handler(&nfqh);
return status;
cleanup_netlink_notifier:
@@ -1424,7 +1431,6 @@ out:
static void __exit nfnetlink_queue_fini(void)
{
- nf_unregister_queue_handler();
unregister_netdevice_notifier(&nfqnl_dev_notifier);
nfnetlink_subsys_unregister(&nfqnl_subsys);
netlink_unregister_notifier(&nfqnl_rtnl_notifier);
--
2.8.1
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