From: Harald Welte Date: Wed, 10 Aug 2005 02:28:03 +0000 (-0700) Subject: [NETFILTER]: connection tracking event notifiers X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ac3247baf8ecadf168642e3898b0212c29c79715;p=linux-beck.git [NETFILTER]: connection tracking event notifiers This adds a notifier chain based event mechanism for ip_conntrack state changes. As opposed to the previous implementations in patch-o-matic, we do no longer need a field in the skb to achieve this. Thanks to the valuable input from Patrick McHardy and Rusty on the idea of a per_cpu implementation. Signed-off-by: Harald Welte Signed-off-by: David S. Miller --- diff --git a/include/linux/netfilter_ipv4/ip_conntrack.h b/include/linux/netfilter_ipv4/ip_conntrack.h index 4ed720f0c4cd..ae1270c97b50 100644 --- a/include/linux/netfilter_ipv4/ip_conntrack.h +++ b/include/linux/netfilter_ipv4/ip_conntrack.h @@ -65,6 +65,63 @@ enum ip_conntrack_status { /* Both together */ IPS_NAT_DONE_MASK = (IPS_DST_NAT_DONE | IPS_SRC_NAT_DONE), + + /* Connection is dying (removed from lists), can not be unset. */ + IPS_DYING_BIT = 9, + IPS_DYING = (1 << IPS_DYING_BIT), +}; + +/* Connection tracking event bits */ +enum ip_conntrack_events +{ + /* New conntrack */ + IPCT_NEW_BIT = 0, + IPCT_NEW = (1 << IPCT_NEW_BIT), + + /* Expected connection */ + IPCT_RELATED_BIT = 1, + IPCT_RELATED = (1 << IPCT_RELATED_BIT), + + /* Destroyed conntrack */ + IPCT_DESTROY_BIT = 2, + IPCT_DESTROY = (1 << IPCT_DESTROY_BIT), + + /* Timer has been refreshed */ + IPCT_REFRESH_BIT = 3, + IPCT_REFRESH = (1 << IPCT_REFRESH_BIT), + + /* Status has changed */ + IPCT_STATUS_BIT = 4, + IPCT_STATUS = (1 << IPCT_STATUS_BIT), + + /* Update of protocol info */ + IPCT_PROTOINFO_BIT = 5, + IPCT_PROTOINFO = (1 << IPCT_PROTOINFO_BIT), + + /* Volatile protocol info */ + IPCT_PROTOINFO_VOLATILE_BIT = 6, + IPCT_PROTOINFO_VOLATILE = (1 << IPCT_PROTOINFO_VOLATILE_BIT), + + /* New helper for conntrack */ + IPCT_HELPER_BIT = 7, + IPCT_HELPER = (1 << IPCT_HELPER_BIT), + + /* Update of helper info */ + IPCT_HELPINFO_BIT = 8, + IPCT_HELPINFO = (1 << IPCT_HELPINFO_BIT), + + /* Volatile helper info */ + IPCT_HELPINFO_VOLATILE_BIT = 9, + IPCT_HELPINFO_VOLATILE = (1 << IPCT_HELPINFO_VOLATILE_BIT), + + /* NAT info */ + IPCT_NATINFO_BIT = 10, + IPCT_NATINFO = (1 << IPCT_NATINFO_BIT), +}; + +enum ip_conntrack_expect_events { + IPEXP_NEW_BIT = 0, + IPEXP_NEW = (1 << IPEXP_NEW_BIT), }; #ifdef __KERNEL__ @@ -280,6 +337,11 @@ static inline int is_confirmed(struct ip_conntrack *ct) return test_bit(IPS_CONFIRMED_BIT, &ct->status); } +static inline int is_dying(struct ip_conntrack *ct) +{ + return test_bit(IPS_DYING_BIT, &ct->status); +} + extern unsigned int ip_conntrack_htable_size; struct ip_conntrack_stat @@ -303,6 +365,88 @@ struct ip_conntrack_stat #define CONNTRACK_STAT_INC(count) (__get_cpu_var(ip_conntrack_stat).count++) +#ifdef CONFIG_IP_NF_CONNTRACK_EVENTS +#include + +struct ip_conntrack_ecache { + struct ip_conntrack *ct; + unsigned int events; +}; +DECLARE_PER_CPU(struct ip_conntrack_ecache, ip_conntrack_ecache); + +#define CONNTRACK_ECACHE(x) (__get_cpu_var(ip_conntrack_ecache).x) + +extern struct notifier_block *ip_conntrack_chain; +extern struct notifier_block *ip_conntrack_expect_chain; + +static inline int ip_conntrack_register_notifier(struct notifier_block *nb) +{ + return notifier_chain_register(&ip_conntrack_chain, nb); +} + +static inline int ip_conntrack_unregister_notifier(struct notifier_block *nb) +{ + return notifier_chain_unregister(&ip_conntrack_chain, nb); +} + +static inline int +ip_conntrack_expect_register_notifier(struct notifier_block *nb) +{ + return notifier_chain_register(&ip_conntrack_expect_chain, nb); +} + +static inline int +ip_conntrack_expect_unregister_notifier(struct notifier_block *nb) +{ + return notifier_chain_unregister(&ip_conntrack_expect_chain, nb); +} + +static inline void +ip_conntrack_event_cache(enum ip_conntrack_events event, + const struct sk_buff *skb) +{ + struct ip_conntrack_ecache *ecache = + &__get_cpu_var(ip_conntrack_ecache); + + if (unlikely((struct ip_conntrack *) skb->nfct != ecache->ct)) { + if (net_ratelimit()) { + printk(KERN_ERR "ctevent: skb->ct != ecache->ct !!!\n"); + dump_stack(); + } + } + ecache->events |= event; +} + +extern void +ip_conntrack_deliver_cached_events_for(const struct ip_conntrack *ct); +extern void ip_conntrack_event_cache_init(const struct sk_buff *skb); + +static inline void ip_conntrack_event(enum ip_conntrack_events event, + struct ip_conntrack *ct) +{ + if (is_confirmed(ct) && !is_dying(ct)) + notifier_call_chain(&ip_conntrack_chain, event, ct); +} + +static inline void +ip_conntrack_expect_event(enum ip_conntrack_expect_events event, + struct ip_conntrack_expect *exp) +{ + notifier_call_chain(&ip_conntrack_expect_chain, event, exp); +} +#else /* CONFIG_IP_NF_CONNTRACK_EVENTS */ +static inline void ip_conntrack_event_cache(enum ip_conntrack_events event, + const struct sk_buff *skb) {} +static inline void ip_conntrack_event(enum ip_conntrack_events event, + struct ip_conntrack *ct) {} +static inline void ip_conntrack_deliver_cached_events_for( + struct ip_conntrack *ct) {} +static inline void ip_conntrack_event_cache_init(const struct sk_buff *skb) {} +static inline void +ip_conntrack_expect_event(enum ip_conntrack_expect_events event, + struct ip_conntrack_expect *exp) {} +#endif /* CONFIG_IP_NF_CONNTRACK_EVENTS */ + #ifdef CONFIG_IP_NF_NAT_NEEDED static inline int ip_nat_initialized(struct ip_conntrack *conntrack, enum ip_nat_manip_type manip) diff --git a/include/linux/netfilter_ipv4/ip_conntrack_core.h b/include/linux/netfilter_ipv4/ip_conntrack_core.h index 694aec9b4784..46eeea1e2733 100644 --- a/include/linux/netfilter_ipv4/ip_conntrack_core.h +++ b/include/linux/netfilter_ipv4/ip_conntrack_core.h @@ -38,12 +38,21 @@ extern int __ip_conntrack_confirm(struct sk_buff **pskb); /* Confirm a connection: returns NF_DROP if packet must be dropped. */ static inline int ip_conntrack_confirm(struct sk_buff **pskb) { - if ((*pskb)->nfct - && !is_confirmed((struct ip_conntrack *)(*pskb)->nfct)) - return __ip_conntrack_confirm(pskb); - return NF_ACCEPT; + struct ip_conntrack *ct = (struct ip_conntrack *)(*pskb)->nfct; + int ret = NF_ACCEPT; + + if (ct && !is_confirmed(ct)) + ret = __ip_conntrack_confirm(pskb); + ip_conntrack_deliver_cached_events_for(ct); + + return ret; } +#ifdef CONFIG_IP_NF_CONNTRACK_EVENTS +struct ip_conntrack_ecache; +extern void __ip_ct_deliver_cached_events(struct ip_conntrack_ecache *ec); +#endif + extern struct list_head *ip_conntrack_hash; extern struct list_head ip_conntrack_expect_list; extern rwlock_t ip_conntrack_lock; diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig index 46d4cb1c06f0..ff3393eba924 100644 --- a/net/ipv4/netfilter/Kconfig +++ b/net/ipv4/netfilter/Kconfig @@ -40,6 +40,16 @@ config IP_NF_CONNTRACK_MARK of packets, but this mark value is kept in the conntrack session instead of the individual packets. +config IP_NF_CONNTRACK_EVENTS + bool "Connection tracking events" + depends on IP_NF_CONNTRACK + help + If this option is enabled, the connection tracking code will + provide a notifier chain that can be used by other kernel code + to get notified about changes in the connection tracking state. + + IF unsure, say `N'. + config IP_NF_CT_PROTO_SCTP tristate 'SCTP protocol connection tracking support (EXPERIMENTAL)' depends on IP_NF_CONNTRACK && EXPERIMENTAL diff --git a/net/ipv4/netfilter/ip_conntrack_core.c b/net/ipv4/netfilter/ip_conntrack_core.c index 04c3414361d4..caf89deae116 100644 --- a/net/ipv4/netfilter/ip_conntrack_core.c +++ b/net/ipv4/netfilter/ip_conntrack_core.c @@ -37,6 +37,7 @@ #include #include #include +#include /* ip_conntrack_lock protects the main hash table, protocol/helper/expected registrations, conntrack timers*/ @@ -49,7 +50,7 @@ #include #include -#define IP_CONNTRACK_VERSION "2.1" +#define IP_CONNTRACK_VERSION "2.2" #if 0 #define DEBUGP printk @@ -76,6 +77,81 @@ unsigned int ip_ct_log_invalid; static LIST_HEAD(unconfirmed); static int ip_conntrack_vmalloc; +#ifdef CONFIG_IP_NF_CONNTRACK_EVENTS +struct notifier_block *ip_conntrack_chain; +struct notifier_block *ip_conntrack_expect_chain; + +DEFINE_PER_CPU(struct ip_conntrack_ecache, ip_conntrack_ecache); + +static inline void __deliver_cached_events(struct ip_conntrack_ecache *ecache) +{ + if (is_confirmed(ecache->ct) && !is_dying(ecache->ct) && ecache->events) + notifier_call_chain(&ip_conntrack_chain, ecache->events, + ecache->ct); + ecache->events = 0; +} + +void __ip_ct_deliver_cached_events(struct ip_conntrack_ecache *ecache) +{ + __deliver_cached_events(ecache); +} + +/* Deliver all cached events for a particular conntrack. This is called + * by code prior to async packet handling or freeing the skb */ +void +ip_conntrack_deliver_cached_events_for(const struct ip_conntrack *ct) +{ + struct ip_conntrack_ecache *ecache = + &__get_cpu_var(ip_conntrack_ecache); + + if (!ct) + return; + + if (ecache->ct == ct) { + DEBUGP("ecache: delivering event for %p\n", ct); + __deliver_cached_events(ecache); + } else { + if (net_ratelimit()) + printk(KERN_WARNING "ecache: want to deliver for %p, " + "but cache has %p\n", ct, ecache->ct); + } + + /* signalize that events have already been delivered */ + ecache->ct = NULL; +} + +/* Deliver cached events for old pending events, if current conntrack != old */ +void ip_conntrack_event_cache_init(const struct sk_buff *skb) +{ + struct ip_conntrack *ct = (struct ip_conntrack *) skb->nfct; + struct ip_conntrack_ecache *ecache = + &__get_cpu_var(ip_conntrack_ecache); + + /* take care of delivering potentially old events */ + if (ecache->ct != ct) { + enum ip_conntrack_info ctinfo; + /* we have to check, since at startup the cache is NULL */ + if (likely(ecache->ct)) { + DEBUGP("ecache: entered for different conntrack: " + "ecache->ct=%p, skb->nfct=%p. delivering " + "events\n", ecache->ct, ct); + __deliver_cached_events(ecache); + ip_conntrack_put(ecache->ct); + } else { + DEBUGP("ecache: entered for conntrack %p, " + "cache was clean before\n", ct); + } + + /* initialize for this conntrack/packet */ + ecache->ct = ip_conntrack_get(skb, &ctinfo); + /* ecache->events cleared by __deliver_cached_devents() */ + } else { + DEBUGP("ecache: re-entered for conntrack %p.\n", ct); + } +} + +#endif /* CONFIG_IP_NF_CONNTRACK_EVENTS */ + DEFINE_PER_CPU(struct ip_conntrack_stat, ip_conntrack_stat); void @@ -223,6 +299,8 @@ destroy_conntrack(struct nf_conntrack *nfct) IP_NF_ASSERT(atomic_read(&nfct->use) == 0); IP_NF_ASSERT(!timer_pending(&ct->timeout)); + set_bit(IPS_DYING_BIT, &ct->status); + /* To make sure we don't get any weird locking issues here: * destroy_conntrack() MUST NOT be called with a write lock * to ip_conntrack_lock!!! -HW */ @@ -261,6 +339,7 @@ static void death_by_timeout(unsigned long ul_conntrack) { struct ip_conntrack *ct = (void *)ul_conntrack; + ip_conntrack_event(IPCT_DESTROY, ct); write_lock_bh(&ip_conntrack_lock); /* Inside lock so preempt is disabled on module removal path. * Otherwise we can get spurious warnings. */ @@ -374,6 +453,16 @@ __ip_conntrack_confirm(struct sk_buff **pskb) set_bit(IPS_CONFIRMED_BIT, &ct->status); CONNTRACK_STAT_INC(insert); write_unlock_bh(&ip_conntrack_lock); + if (ct->helper) + ip_conntrack_event_cache(IPCT_HELPER, *pskb); +#ifdef CONFIG_IP_NF_NAT_NEEDED + if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || + test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) + ip_conntrack_event_cache(IPCT_NATINFO, *pskb); +#endif + ip_conntrack_event_cache(master_ct(ct) ? + IPCT_RELATED : IPCT_NEW, *pskb); + return NF_ACCEPT; } @@ -607,7 +696,7 @@ unsigned int ip_conntrack_in(unsigned int hooknum, struct ip_conntrack *ct; enum ip_conntrack_info ctinfo; struct ip_conntrack_protocol *proto; - int set_reply; + int set_reply = 0; int ret; /* Previously seen (loopback or untracked)? Ignore. */ @@ -666,6 +755,8 @@ unsigned int ip_conntrack_in(unsigned int hooknum, IP_NF_ASSERT((*pskb)->nfct); + ip_conntrack_event_cache_init(*pskb); + ret = proto->packet(ct, *pskb, ctinfo); if (ret < 0) { /* Invalid: inverse of the return code tells @@ -676,8 +767,8 @@ unsigned int ip_conntrack_in(unsigned int hooknum, return -ret; } - if (set_reply) - set_bit(IPS_SEEN_REPLY_BIT, &ct->status); + if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) + ip_conntrack_event_cache(IPCT_STATUS, *pskb); return ret; } @@ -824,6 +915,7 @@ int ip_conntrack_expect_related(struct ip_conntrack_expect *expect) evict_oldest_expect(expect->master); ip_conntrack_expect_insert(expect); + ip_conntrack_expect_event(IPEXP_NEW, expect); ret = 0; out: write_unlock_bh(&ip_conntrack_lock); @@ -861,8 +953,10 @@ int ip_conntrack_helper_register(struct ip_conntrack_helper *me) static inline int unhelp(struct ip_conntrack_tuple_hash *i, const struct ip_conntrack_helper *me) { - if (tuplehash_to_ctrack(i)->helper == me) + if (tuplehash_to_ctrack(i)->helper == me) { + ip_conntrack_event(IPCT_HELPER, tuplehash_to_ctrack(i)); tuplehash_to_ctrack(i)->helper = NULL; + } return 0; } @@ -924,6 +1018,7 @@ void ip_ct_refresh_acct(struct ip_conntrack *ct, if (del_timer(&ct->timeout)) { ct->timeout.expires = jiffies + extra_jiffies; add_timer(&ct->timeout); + ip_conntrack_event_cache(IPCT_REFRESH, skb); } ct_add_counters(ct, ctinfo, skb); write_unlock_bh(&ip_conntrack_lock); @@ -1012,6 +1107,23 @@ ip_ct_iterate_cleanup(int (*iter)(struct ip_conntrack *i, void *), void *data) ip_conntrack_put(ct); } + +#ifdef CONFIG_IP_NF_CONNTRACK_EVENTS + { + /* we need to deliver all cached events in order to drop + * the reference counts */ + int cpu; + for_each_cpu(cpu) { + struct ip_conntrack_ecache *ecache = + &per_cpu(ip_conntrack_ecache, cpu); + if (ecache->ct) { + __ip_ct_deliver_cached_events(ecache); + ip_conntrack_put(ecache->ct); + ecache->ct = NULL; + } + } + } +#endif } /* Fast function for those who don't want to parse /proc (and I don't diff --git a/net/ipv4/netfilter/ip_conntrack_ftp.c b/net/ipv4/netfilter/ip_conntrack_ftp.c index 7a3b773be3f9..9658896f899a 100644 --- a/net/ipv4/netfilter/ip_conntrack_ftp.c +++ b/net/ipv4/netfilter/ip_conntrack_ftp.c @@ -262,7 +262,8 @@ static int find_nl_seq(u32 seq, const struct ip_ct_ftp_master *info, int dir) } /* We don't update if it's older than what we have. */ -static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir) +static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir, + struct sk_buff *skb) { unsigned int i, oldest = NUM_SEQ_TO_REMEMBER; @@ -276,10 +277,13 @@ static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir) oldest = i; } - if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) + if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) { info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq; - else if (oldest != NUM_SEQ_TO_REMEMBER) + ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb); + } else if (oldest != NUM_SEQ_TO_REMEMBER) { info->seq_aft_nl[dir][oldest] = nl_seq; + ip_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb); + } } static int help(struct sk_buff **pskb, @@ -439,7 +443,7 @@ out_update_nl: /* Now if this ends in \n, update ftp info. Seq may have been * adjusted by NAT code. */ if (ends_in_nl) - update_nl_seq(seq, ct_ftp_info,dir); + update_nl_seq(seq, ct_ftp_info,dir, *pskb); out: spin_unlock_bh(&ip_ftp_lock); return ret; diff --git a/net/ipv4/netfilter/ip_conntrack_proto_icmp.c b/net/ipv4/netfilter/ip_conntrack_proto_icmp.c index 602c74db3252..dca1f63d6f51 100644 --- a/net/ipv4/netfilter/ip_conntrack_proto_icmp.c +++ b/net/ipv4/netfilter/ip_conntrack_proto_icmp.c @@ -102,6 +102,7 @@ static int icmp_packet(struct ip_conntrack *ct, ct->timeout.function((unsigned long)ct); } else { atomic_inc(&ct->proto.icmp.count); + ip_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); ip_ct_refresh_acct(ct, ctinfo, skb, ip_ct_icmp_timeout); } diff --git a/net/ipv4/netfilter/ip_conntrack_proto_sctp.c b/net/ipv4/netfilter/ip_conntrack_proto_sctp.c index 31d75390bf12..3d5f878a07d1 100644 --- a/net/ipv4/netfilter/ip_conntrack_proto_sctp.c +++ b/net/ipv4/netfilter/ip_conntrack_proto_sctp.c @@ -404,6 +404,8 @@ static int sctp_packet(struct ip_conntrack *conntrack, } conntrack->proto.sctp.state = newconntrack; + if (oldsctpstate != newconntrack) + ip_conntrack_event_cache(IPCT_PROTOINFO, skb); write_unlock_bh(&sctp_lock); } diff --git a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c index 809dfed766d4..a569ad1ee4d9 100644 --- a/net/ipv4/netfilter/ip_conntrack_proto_tcp.c +++ b/net/ipv4/netfilter/ip_conntrack_proto_tcp.c @@ -973,6 +973,10 @@ static int tcp_packet(struct ip_conntrack *conntrack, ? ip_ct_tcp_timeout_max_retrans : *tcp_timeouts[new_state]; write_unlock_bh(&tcp_lock); + ip_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb); + if (new_state != old_state) + ip_conntrack_event_cache(IPCT_PROTOINFO, skb); + if (!test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) { /* If only reply is a RST, we can consider ourselves not to have an established connection: this is a fairly common diff --git a/net/ipv4/netfilter/ip_conntrack_proto_udp.c b/net/ipv4/netfilter/ip_conntrack_proto_udp.c index 8c1eaba098d4..6066eaf4d825 100644 --- a/net/ipv4/netfilter/ip_conntrack_proto_udp.c +++ b/net/ipv4/netfilter/ip_conntrack_proto_udp.c @@ -73,7 +73,8 @@ static int udp_packet(struct ip_conntrack *conntrack, ip_ct_refresh_acct(conntrack, ctinfo, skb, ip_ct_udp_timeout_stream); /* Also, more likely to be important, and not a probe */ - set_bit(IPS_ASSURED_BIT, &conntrack->status); + if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status)) + ip_conntrack_event_cache(IPCT_STATUS, skb); } else ip_ct_refresh_acct(conntrack, ctinfo, skb, ip_ct_udp_timeout); diff --git a/net/ipv4/netfilter/ip_conntrack_standalone.c b/net/ipv4/netfilter/ip_conntrack_standalone.c index dccd4abab7ae..f0880004115d 100644 --- a/net/ipv4/netfilter/ip_conntrack_standalone.c +++ b/net/ipv4/netfilter/ip_conntrack_standalone.c @@ -402,6 +402,7 @@ static unsigned int ip_confirm(unsigned int hooknum, const struct net_device *out, int (*okfn)(struct sk_buff *)) { + ip_conntrack_event_cache_init(*pskb); /* We've seen it coming out the other side: confirm it */ return ip_conntrack_confirm(pskb); } @@ -419,6 +420,7 @@ static unsigned int ip_conntrack_help(unsigned int hooknum, ct = ip_conntrack_get(*pskb, &ctinfo); if (ct && ct->helper) { unsigned int ret; + ip_conntrack_event_cache_init(*pskb); ret = ct->helper->help(pskb, ct, ctinfo); if (ret != NF_ACCEPT) return ret; @@ -889,6 +891,7 @@ static int init_or_cleanup(int init) return ret; cleanup: + synchronize_net(); #ifdef CONFIG_SYSCTL unregister_sysctl_table(ip_ct_sysctl_header); cleanup_localinops: @@ -971,6 +974,13 @@ void need_ip_conntrack(void) { } +#ifdef CONFIG_IP_NF_CONNTRACK_EVENTS +EXPORT_SYMBOL_GPL(ip_conntrack_chain); +EXPORT_SYMBOL_GPL(ip_conntrack_expect_chain); +EXPORT_SYMBOL_GPL(ip_conntrack_register_notifier); +EXPORT_SYMBOL_GPL(ip_conntrack_unregister_notifier); +EXPORT_PER_CPU_SYMBOL_GPL(ip_conntrack_ecache); +#endif EXPORT_SYMBOL(ip_conntrack_protocol_register); EXPORT_SYMBOL(ip_conntrack_protocol_unregister); EXPORT_SYMBOL(ip_ct_get_tuple);