From 70e9942f17a6193e9172a804e6569a8806633d6b Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 22 Nov 2011 00:16:51 +0100 Subject: netfilter: nf_conntrack: make event callback registration per-netns This patch fixes an oops that can be triggered following this recipe: 0) make sure nf_conntrack_netlink and nf_conntrack_ipv4 are loaded. 1) container is started. 2) connect to it via lxc-console. 3) generate some traffic with the container to create some conntrack entries in its table. 4) stop the container: you hit one oops because the conntrack table cleanup tries to report the destroy event to user-space but the per-netns nfnetlink socket has already gone (as the nfnetlink socket is per-netns but event callback registration is global). To fix this situation, we make the ctnl_notifier per-netns so the callback is registered/unregistered if the container is created/destroyed. Alex Bligh and Alexey Dobriyan originally proposed one small patch to check if the nfnetlink socket is gone in nfnetlink_has_listeners, but this is a very visited path for events, thus, it may reduce performance and it looks a bit hackish to check for the nfnetlink socket only to workaround this situation. As a result, I decided to follow the bigger path choice, which seems to look nicer to me. Cc: Alexey Dobriyan Reported-by: Alex Bligh Signed-off-by: Pablo Neira Ayuso diff --git a/include/net/netfilter/nf_conntrack_ecache.h b/include/net/netfilter/nf_conntrack_ecache.h index 4283508..a88fb69 100644 --- a/include/net/netfilter/nf_conntrack_ecache.h +++ b/include/net/netfilter/nf_conntrack_ecache.h @@ -67,18 +67,18 @@ struct nf_ct_event_notifier { int (*fcn)(unsigned int events, struct nf_ct_event *item); }; -extern struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb; -extern int nf_conntrack_register_notifier(struct nf_ct_event_notifier *nb); -extern void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *nb); +extern int nf_conntrack_register_notifier(struct net *net, struct nf_ct_event_notifier *nb); +extern void nf_conntrack_unregister_notifier(struct net *net, struct nf_ct_event_notifier *nb); extern void nf_ct_deliver_cached_events(struct nf_conn *ct); static inline void nf_conntrack_event_cache(enum ip_conntrack_events event, struct nf_conn *ct) { + struct net *net = nf_ct_net(ct); struct nf_conntrack_ecache *e; - if (nf_conntrack_event_cb == NULL) + if (net->ct.nf_conntrack_event_cb == NULL) return; e = nf_ct_ecache_find(ct); @@ -95,11 +95,12 @@ nf_conntrack_eventmask_report(unsigned int eventmask, int report) { int ret = 0; + struct net *net = nf_ct_net(ct); struct nf_ct_event_notifier *notify; struct nf_conntrack_ecache *e; rcu_read_lock(); - notify = rcu_dereference(nf_conntrack_event_cb); + notify = rcu_dereference(net->ct.nf_conntrack_event_cb); if (notify == NULL) goto out_unlock; @@ -164,9 +165,8 @@ struct nf_exp_event_notifier { int (*fcn)(unsigned int events, struct nf_exp_event *item); }; -extern struct nf_exp_event_notifier __rcu *nf_expect_event_cb; -extern int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *nb); -extern void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *nb); +extern int nf_ct_expect_register_notifier(struct net *net, struct nf_exp_event_notifier *nb); +extern void nf_ct_expect_unregister_notifier(struct net *net, struct nf_exp_event_notifier *nb); static inline void nf_ct_expect_event_report(enum ip_conntrack_expect_events event, @@ -174,11 +174,12 @@ nf_ct_expect_event_report(enum ip_conntrack_expect_events event, u32 pid, int report) { + struct net *net = nf_ct_exp_net(exp); struct nf_exp_event_notifier *notify; struct nf_conntrack_ecache *e; rcu_read_lock(); - notify = rcu_dereference(nf_expect_event_cb); + notify = rcu_dereference(net->ct.nf_expect_event_cb); if (notify == NULL) goto out_unlock; diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h index 0249399..7a911ec 100644 --- a/include/net/netns/conntrack.h +++ b/include/net/netns/conntrack.h @@ -18,6 +18,8 @@ struct netns_ct { struct hlist_nulls_head unconfirmed; struct hlist_nulls_head dying; struct ip_conntrack_stat __percpu *stat; + struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb; + struct nf_exp_event_notifier __rcu *nf_expect_event_cb; int sysctl_events; unsigned int sysctl_events_retry_timeout; int sysctl_acct; diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c index 6b368be..b62c414 100644 --- a/net/netfilter/nf_conntrack_ecache.c +++ b/net/netfilter/nf_conntrack_ecache.c @@ -27,22 +27,17 @@ static DEFINE_MUTEX(nf_ct_ecache_mutex); -struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb __read_mostly; -EXPORT_SYMBOL_GPL(nf_conntrack_event_cb); - -struct nf_exp_event_notifier __rcu *nf_expect_event_cb __read_mostly; -EXPORT_SYMBOL_GPL(nf_expect_event_cb); - /* deliver cached events and clear cache entry - must be called with locally * disabled softirqs */ void nf_ct_deliver_cached_events(struct nf_conn *ct) { + struct net *net = nf_ct_net(ct); unsigned long events; struct nf_ct_event_notifier *notify; struct nf_conntrack_ecache *e; rcu_read_lock(); - notify = rcu_dereference(nf_conntrack_event_cb); + notify = rcu_dereference(net->ct.nf_conntrack_event_cb); if (notify == NULL) goto out_unlock; @@ -83,19 +78,20 @@ out_unlock: } EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events); -int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new) +int nf_conntrack_register_notifier(struct net *net, + struct nf_ct_event_notifier *new) { int ret = 0; struct nf_ct_event_notifier *notify; mutex_lock(&nf_ct_ecache_mutex); - notify = rcu_dereference_protected(nf_conntrack_event_cb, + notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb, lockdep_is_held(&nf_ct_ecache_mutex)); if (notify != NULL) { ret = -EBUSY; goto out_unlock; } - RCU_INIT_POINTER(nf_conntrack_event_cb, new); + RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, new); mutex_unlock(&nf_ct_ecache_mutex); return ret; @@ -105,32 +101,34 @@ out_unlock: } EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier); -void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new) +void nf_conntrack_unregister_notifier(struct net *net, + struct nf_ct_event_notifier *new) { struct nf_ct_event_notifier *notify; mutex_lock(&nf_ct_ecache_mutex); - notify = rcu_dereference_protected(nf_conntrack_event_cb, + notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb, lockdep_is_held(&nf_ct_ecache_mutex)); BUG_ON(notify != new); - RCU_INIT_POINTER(nf_conntrack_event_cb, NULL); + RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL); mutex_unlock(&nf_ct_ecache_mutex); } EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier); -int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new) +int nf_ct_expect_register_notifier(struct net *net, + struct nf_exp_event_notifier *new) { int ret = 0; struct nf_exp_event_notifier *notify; mutex_lock(&nf_ct_ecache_mutex); - notify = rcu_dereference_protected(nf_expect_event_cb, + notify = rcu_dereference_protected(net->ct.nf_expect_event_cb, lockdep_is_held(&nf_ct_ecache_mutex)); if (notify != NULL) { ret = -EBUSY; goto out_unlock; } - RCU_INIT_POINTER(nf_expect_event_cb, new); + RCU_INIT_POINTER(net->ct.nf_expect_event_cb, new); mutex_unlock(&nf_ct_ecache_mutex); return ret; @@ -140,15 +138,16 @@ out_unlock: } EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier); -void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new) +void nf_ct_expect_unregister_notifier(struct net *net, + struct nf_exp_event_notifier *new) { struct nf_exp_event_notifier *notify; mutex_lock(&nf_ct_ecache_mutex); - notify = rcu_dereference_protected(nf_expect_event_cb, + notify = rcu_dereference_protected(net->ct.nf_expect_event_cb, lockdep_is_held(&nf_ct_ecache_mutex)); BUG_ON(notify != new); - RCU_INIT_POINTER(nf_expect_event_cb, NULL); + RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL); mutex_unlock(&nf_ct_ecache_mutex); } EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index e58aa9b..ef21b22 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -4,7 +4,7 @@ * (C) 2001 by Jay Schulist * (C) 2002-2006 by Harald Welte * (C) 2003 by Patrick Mchardy - * (C) 2005-2008 by Pablo Neira Ayuso + * (C) 2005-2011 by Pablo Neira Ayuso * * Initial connection tracking via netlink development funded and * generally made possible by Network Robots, Inc. (www.networkrobots.com) @@ -2163,6 +2163,54 @@ MODULE_ALIAS("ip_conntrack_netlink"); MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK); MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_EXP); +static int __net_init ctnetlink_net_init(struct net *net) +{ +#ifdef CONFIG_NF_CONNTRACK_EVENTS + int ret; + + ret = nf_conntrack_register_notifier(net, &ctnl_notifier); + if (ret < 0) { + pr_err("ctnetlink_init: cannot register notifier.\n"); + goto err_out; + } + + ret = nf_ct_expect_register_notifier(net, &ctnl_notifier_exp); + if (ret < 0) { + pr_err("ctnetlink_init: cannot expect register notifier.\n"); + goto err_unreg_notifier; + } +#endif + return 0; + +#ifdef CONFIG_NF_CONNTRACK_EVENTS +err_unreg_notifier: + nf_conntrack_unregister_notifier(net, &ctnl_notifier); +err_out: + return ret; +#endif +} + +static void ctnetlink_net_exit(struct net *net) +{ +#ifdef CONFIG_NF_CONNTRACK_EVENTS + nf_ct_expect_unregister_notifier(net, &ctnl_notifier_exp); + nf_conntrack_unregister_notifier(net, &ctnl_notifier); +#endif +} + +static void __net_exit ctnetlink_net_exit_batch(struct list_head *net_exit_list) +{ + struct net *net; + + list_for_each_entry(net, net_exit_list, exit_list) + ctnetlink_net_exit(net); +} + +static struct pernet_operations ctnetlink_net_ops = { + .init = ctnetlink_net_init, + .exit_batch = ctnetlink_net_exit_batch, +}; + static int __init ctnetlink_init(void) { int ret; @@ -2180,28 +2228,15 @@ static int __init ctnetlink_init(void) goto err_unreg_subsys; } -#ifdef CONFIG_NF_CONNTRACK_EVENTS - ret = nf_conntrack_register_notifier(&ctnl_notifier); - if (ret < 0) { - pr_err("ctnetlink_init: cannot register notifier.\n"); + if (register_pernet_subsys(&ctnetlink_net_ops)) { + pr_err("ctnetlink_init: cannot register pernet operations\n"); goto err_unreg_exp_subsys; } - ret = nf_ct_expect_register_notifier(&ctnl_notifier_exp); - if (ret < 0) { - pr_err("ctnetlink_init: cannot expect register notifier.\n"); - goto err_unreg_notifier; - } -#endif - return 0; -#ifdef CONFIG_NF_CONNTRACK_EVENTS -err_unreg_notifier: - nf_conntrack_unregister_notifier(&ctnl_notifier); err_unreg_exp_subsys: nfnetlink_subsys_unregister(&ctnl_exp_subsys); -#endif err_unreg_subsys: nfnetlink_subsys_unregister(&ctnl_subsys); err_out: @@ -2213,11 +2248,7 @@ static void __exit ctnetlink_exit(void) pr_info("ctnetlink: unregistering from nfnetlink.\n"); nf_ct_remove_userspace_expectations(); -#ifdef CONFIG_NF_CONNTRACK_EVENTS - nf_ct_expect_unregister_notifier(&ctnl_notifier_exp); - nf_conntrack_unregister_notifier(&ctnl_notifier); -#endif - + unregister_pernet_subsys(&ctnetlink_net_ops); nfnetlink_subsys_unregister(&ctnl_exp_subsys); nfnetlink_subsys_unregister(&ctnl_subsys); } -- cgit v0.10.2