netfilter: 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@strlen.de> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ -28,8 +28,8 @@ struct nf_queue_handler {
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struct nf_hook_ops *ops);
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};
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void nf_register_queue_handler(const struct nf_queue_handler *qh);
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void nf_unregister_queue_handler(void);
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void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh);
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void nf_unregister_queue_handler(struct net *net);
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void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
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void nf_queue_entry_get_refs(struct nf_queue_entry *entry);
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@ -5,11 +5,13 @@
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struct proc_dir_entry;
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struct nf_logger;
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struct nf_queue_handler;
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struct netns_nf {
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#if defined CONFIG_PROC_FS
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struct proc_dir_entry *proc_netfilter;
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#endif
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const struct nf_queue_handler __rcu *queue_handler;
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const struct nf_logger __rcu *nf_loggers[NFPROTO_NUMPROTO];
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#ifdef CONFIG_SYSCTL
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struct ctl_table_header *nf_log_dir_header;
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@ -26,23 +26,21 @@
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* Once the queue is registered it must reinject all packets it
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* receives, no matter what.
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*/
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static const struct nf_queue_handler __rcu *queue_handler __read_mostly;
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/* return EBUSY when somebody else is registered, return EEXIST if the
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* same handler is registered, return 0 in case of success. */
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void nf_register_queue_handler(const struct nf_queue_handler *qh)
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void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh)
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{
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/* should never happen, we only have one queueing backend in kernel */
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WARN_ON(rcu_access_pointer(queue_handler));
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rcu_assign_pointer(queue_handler, qh);
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WARN_ON(rcu_access_pointer(net->nf.queue_handler));
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rcu_assign_pointer(net->nf.queue_handler, qh);
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}
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EXPORT_SYMBOL(nf_register_queue_handler);
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/* The caller must flush their queue before this */
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void nf_unregister_queue_handler(void)
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void nf_unregister_queue_handler(struct net *net)
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{
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RCU_INIT_POINTER(queue_handler, NULL);
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synchronize_rcu();
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RCU_INIT_POINTER(net->nf.queue_handler, NULL);
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}
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EXPORT_SYMBOL(nf_unregister_queue_handler);
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@ -103,7 +101,7 @@ void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops)
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const struct nf_queue_handler *qh;
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rcu_read_lock();
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qh = rcu_dereference(queue_handler);
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qh = rcu_dereference(net->nf.queue_handler);
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if (qh)
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qh->nf_hook_drop(net, ops);
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rcu_read_unlock();
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@ -122,9 +120,10 @@ int nf_queue(struct sk_buff *skb,
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struct nf_queue_entry *entry = NULL;
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const struct nf_afinfo *afinfo;
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const struct nf_queue_handler *qh;
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struct net *net = state->net;
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/* QUEUE == DROP if no one is waiting, to be safe. */
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qh = rcu_dereference(queue_handler);
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qh = rcu_dereference(net->nf.queue_handler);
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if (!qh) {
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status = -ESRCH;
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goto err;
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@ -1377,21 +1377,29 @@ static int __net_init nfnl_queue_net_init(struct net *net)
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net->nf.proc_netfilter, &nfqnl_file_ops))
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return -ENOMEM;
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#endif
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nf_register_queue_handler(net, &nfqh);
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return 0;
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}
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static void __net_exit nfnl_queue_net_exit(struct net *net)
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{
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nf_unregister_queue_handler(net);
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#ifdef CONFIG_PROC_FS
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remove_proc_entry("nfnetlink_queue", net->nf.proc_netfilter);
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#endif
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}
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static void nfnl_queue_net_exit_batch(struct list_head *net_exit_list)
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{
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synchronize_rcu();
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}
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static struct pernet_operations nfnl_queue_net_ops = {
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.init = nfnl_queue_net_init,
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.exit = nfnl_queue_net_exit,
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.id = &nfnl_queue_net_id,
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.size = sizeof(struct nfnl_queue_net),
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.init = nfnl_queue_net_init,
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.exit = nfnl_queue_net_exit,
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.exit_batch = nfnl_queue_net_exit_batch,
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.id = &nfnl_queue_net_id,
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.size = sizeof(struct nfnl_queue_net),
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};
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static int __init nfnetlink_queue_init(void)
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@ -1412,7 +1420,6 @@ static int __init nfnetlink_queue_init(void)
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}
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register_netdevice_notifier(&nfqnl_dev_notifier);
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nf_register_queue_handler(&nfqh);
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return status;
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cleanup_netlink_notifier:
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@ -1424,7 +1431,6 @@ out:
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static void __exit nfnetlink_queue_fini(void)
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{
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nf_unregister_queue_handler();
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unregister_netdevice_notifier(&nfqnl_dev_notifier);
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nfnetlink_subsys_unregister(&nfqnl_subsys);
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netlink_unregister_notifier(&nfqnl_rtnl_notifier);
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