/* Connection state tracking for netfilter. This is separated from, but required by, the NAT layer; it can also be used by an iptables extension. */ /* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2006 Netfilter Core Team * (C) 2003,2004 USAGI/WIDE Project * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * 23 Apr 2001: Harald Welte * - new API and handling of conntrack/nat helpers * - now capable of multiple expectations for one master * 16 Jul 2002: Harald Welte * - add usage/reference counts to ip_conntrack_expect * - export ip_conntrack[_expect]_{find_get,put} functions * 16 Dec 2003: Yasuyuki Kozakai @USAGI * - generalize L3 protocol denendent part. * 23 Mar 2004: Yasuyuki Kozakai @USAGI * - add support various size of conntrack structures. * 26 Jan 2006: Harald Welte * - restructure nf_conn (introduce nf_conn_help) * - redesign 'features' how they were originally intended * 26 Feb 2006: Pablo Neira Ayuso * - add support for L3 protocol module load on demand. * * Derived from net/ipv4/netfilter/ip_conntrack_core.c */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NF_CONNTRACK_VERSION "0.5.0" #if 0 #define DEBUGP printk #else #define DEBUGP(format, args...) #endif DEFINE_RWLOCK(nf_conntrack_lock); EXPORT_SYMBOL_GPL(nf_conntrack_lock); /* nf_conntrack_standalone needs this */ atomic_t nf_conntrack_count = ATOMIC_INIT(0); EXPORT_SYMBOL_GPL(nf_conntrack_count); void (*nf_conntrack_destroyed)(struct nf_conn *conntrack); EXPORT_SYMBOL_GPL(nf_conntrack_destroyed); unsigned int nf_conntrack_htable_size __read_mostly; EXPORT_SYMBOL_GPL(nf_conntrack_htable_size); int nf_conntrack_max __read_mostly; EXPORT_SYMBOL_GPL(nf_conntrack_max); struct list_head *nf_conntrack_hash __read_mostly; EXPORT_SYMBOL_GPL(nf_conntrack_hash); struct nf_conn nf_conntrack_untracked __read_mostly; EXPORT_SYMBOL_GPL(nf_conntrack_untracked); unsigned int nf_ct_log_invalid __read_mostly; LIST_HEAD(unconfirmed); static int nf_conntrack_vmalloc __read_mostly; static unsigned int nf_conntrack_next_id; DEFINE_PER_CPU(struct ip_conntrack_stat, nf_conntrack_stat); EXPORT_PER_CPU_SYMBOL(nf_conntrack_stat); /* * This scheme offers various size of "struct nf_conn" dependent on * features(helper, nat, ...) */ #define NF_CT_FEATURES_NAMELEN 256 static struct { /* name of slab cache. printed in /proc/slabinfo */ char *name; /* size of slab cache */ size_t size; /* slab cache pointer */ struct kmem_cache *cachep; /* allocated slab cache + modules which uses this slab cache */ int use; } nf_ct_cache[NF_CT_F_NUM]; /* protect members of nf_ct_cache except of "use" */ DEFINE_RWLOCK(nf_ct_cache_lock); /* This avoids calling kmem_cache_create() with same name simultaneously */ static DEFINE_MUTEX(nf_ct_cache_mutex); static int nf_conntrack_hash_rnd_initted; static unsigned int nf_conntrack_hash_rnd; static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, unsigned int size, unsigned int rnd) { unsigned int a, b; a = jhash((void *)tuple->src.u3.all, sizeof(tuple->src.u3.all), ((tuple->src.l3num) << 16) | tuple->dst.protonum); b = jhash((void *)tuple->dst.u3.all, sizeof(tuple->dst.u3.all), (tuple->src.u.all << 16) | tuple->dst.u.all); return jhash_2words(a, b, rnd) % size; } static inline u_int32_t hash_conntrack(const struct nf_conntrack_tuple *tuple) { return __hash_conntrack(tuple, nf_conntrack_htable_size, nf_conntrack_hash_rnd); } int nf_conntrack_register_cache(u_int32_t features, const char *name, size_t size) { int ret = 0; char *cache_name; struct kmem_cache *cachep; DEBUGP("nf_conntrack_register_cache: features=0x%x, name=%s, size=%d\n", features, name, size); if (features < NF_CT_F_BASIC || features >= NF_CT_F_NUM) { DEBUGP("nf_conntrack_register_cache: invalid features.: 0x%x\n", features); return -EINVAL; } mutex_lock(&nf_ct_cache_mutex); write_lock_bh(&nf_ct_cache_lock); /* e.g: multiple helpers are loaded */ if (nf_ct_cache[features].use > 0) { DEBUGP("nf_conntrack_register_cache: already resisterd.\n"); if ((!strncmp(nf_ct_cache[features].name, name, NF_CT_FEATURES_NAMELEN)) && nf_ct_cache[features].size == size) { DEBUGP("nf_conntrack_register_cache: reusing.\n"); nf_ct_cache[features].use++; ret = 0; } else ret = -EBUSY; write_unlock_bh(&nf_ct_cache_lock); mutex_unlock(&nf_ct_cache_mutex); return ret; } write_unlock_bh(&nf_ct_cache_lock); /* * The memory space for name of slab cache must be alive until * cache is destroyed. */ cache_name = kmalloc(sizeof(char)*NF_CT_FEATURES_NAMELEN, GFP_ATOMIC); if (cache_name == NULL) { DEBUGP("nf_conntrack_register_cache: can't alloc cache_name\n"); ret = -ENOMEM; goto out_up_mutex; } if (strlcpy(cache_name, name, NF_CT_FEATURES_NAMELEN) >= NF_CT_FEATURES_NAMELEN) { printk("nf_conntrack_register_cache: name too long\n"); ret = -EINVAL; goto out_free_name; } cachep = kmem_cache_create(cache_name, size, 0, 0, NULL, NULL); if (!cachep) { printk("nf_conntrack_register_cache: Can't create slab cache " "for the features = 0x%x\n", features); ret = -ENOMEM; goto out_free_name; } write_lock_bh(&nf_ct_cache_lock); nf_ct_cache[features].use = 1; nf_ct_cache[features].size = size; nf_ct_cache[features].cachep = cachep; nf_ct_cache[features].name = cache_name; write_unlock_bh(&nf_ct_cache_lock); goto out_up_mutex; out_free_name: kfree(cache_name); out_up_mutex: mutex_unlock(&nf_ct_cache_mutex); return ret; } EXPORT_SYMBOL_GPL(nf_conntrack_register_cache); /* FIXME: In the current, only nf_conntrack_cleanup() can call this function. */ void nf_conntrack_unregister_cache(u_int32_t features) { struct kmem_cache *cachep; char *name; /* * This assures that kmem_cache_create() isn't called before destroying * slab cache. */ DEBUGP("nf_conntrack_unregister_cache: 0x%04x\n", features); mutex_lock(&nf_ct_cache_mutex); write_lock_bh(&nf_ct_cache_lock); if (--nf_ct_cache[features].use > 0) { write_unlock_bh(&nf_ct_cache_lock); mutex_unlock(&nf_ct_cache_mutex); return; } cachep = nf_ct_cache[features].cachep; name = nf_ct_cache[features].name; nf_ct_cache[features].cachep = NULL; nf_ct_cache[features].name = NULL; nf_ct_cache[features].size = 0; write_unlock_bh(&nf_ct_cache_lock); synchronize_net(); kmem_cache_destroy(cachep); kfree(name); mutex_unlock(&nf_ct_cache_mutex); } EXPORT_SYMBOL_GPL(nf_conntrack_unregister_cache); int nf_ct_get_tuple(const struct sk_buff *skb, unsigned int nhoff, unsigned int dataoff, u_int16_t l3num, u_int8_t protonum, struct nf_conntrack_tuple *tuple, const struct nf_conntrack_l3proto *l3proto, const struct nf_conntrack_l4proto *l4proto) { NF_CT_TUPLE_U_BLANK(tuple); tuple->src.l3num = l3num; if (l3proto->pkt_to_tuple(skb, nhoff, tuple) == 0) return 0; tuple->dst.protonum = protonum; tuple->dst.dir = IP_CT_DIR_ORIGINAL; return l4proto->pkt_to_tuple(skb, dataoff, tuple); } EXPORT_SYMBOL_GPL(nf_ct_get_tuple); int nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse, const struct nf_conntrack_tuple *orig, const struct nf_conntrack_l3proto *l3proto, const struct nf_conntrack_l4proto *l4proto) { NF_CT_TUPLE_U_BLANK(inverse); inverse->src.l3num = orig->src.l3num; if (l3proto->invert_tuple(inverse, orig) == 0) return 0; inverse->dst.dir = !orig->dst.dir; inverse->dst.protonum = orig->dst.protonum; return l4proto->invert_tuple(inverse, orig); } EXPORT_SYMBOL_GPL(nf_ct_invert_tuple); static void clean_from_lists(struct nf_conn *ct) { DEBUGP("clean_from_lists(%p)\n", ct); list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); list_del(&ct->tuplehash[IP_CT_DIR_REPLY].list); /* Destroy all pending expectations */ nf_ct_remove_expectations(ct); } static void destroy_conntrack(struct nf_conntrack *nfct) { struct nf_conn *ct = (struct nf_conn *)nfct; struct nf_conn_help *help = nfct_help(ct); struct nf_conntrack_l3proto *l3proto; struct nf_conntrack_l4proto *l4proto; typeof(nf_conntrack_destroyed) destroyed; DEBUGP("destroy_conntrack(%p)\n", ct); NF_CT_ASSERT(atomic_read(&nfct->use) == 0); NF_CT_ASSERT(!timer_pending(&ct->timeout)); nf_conntrack_event(IPCT_DESTROY, ct); set_bit(IPS_DYING_BIT, &ct->status); if (help && help->helper && help->helper->destroy) help->helper->destroy(ct); /* To make sure we don't get any weird locking issues here: * destroy_conntrack() MUST NOT be called with a write lock * to nf_conntrack_lock!!! -HW */ rcu_read_lock(); l3proto = __nf_ct_l3proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num); if (l3proto && l3proto->destroy) l3proto->destroy(ct); l4proto = __nf_ct_l4proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.l3num, ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum); if (l4proto && l4proto->destroy) l4proto->destroy(ct); destroyed = rcu_dereference(nf_conntrack_destroyed); if (destroyed) destroyed(ct); rcu_read_unlock(); write_lock_bh(&nf_conntrack_lock); /* Expectations will have been removed in clean_from_lists, * except TFTP can create an expectation on the first packet, * before connection is in the list, so we need to clean here, * too. */ nf_ct_remove_expectations(ct); /* We overload first tuple to link into unconfirmed list. */ if (!nf_ct_is_confirmed(ct)) { BUG_ON(list_empty(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list)); list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); } NF_CT_STAT_INC(delete); write_unlock_bh(&nf_conntrack_lock); if (ct->master) nf_ct_put(ct->master); DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct); nf_conntrack_free(ct); } static void death_by_timeout(unsigned long ul_conntrack) { struct nf_conn *ct = (void *)ul_conntrack; write_lock_bh(&nf_conntrack_lock); /* Inside lock so preempt is disabled on module removal path. * Otherwise we can get spurious warnings. */ NF_CT_STAT_INC(delete_list); clean_from_lists(ct); write_unlock_bh(&nf_conntrack_lock); nf_ct_put(ct); } struct nf_conntrack_tuple_hash * __nf_conntrack_find(const struct nf_conntrack_tuple *tuple, const struct nf_conn *ignored_conntrack) { struct nf_conntrack_tuple_hash *h; unsigned int hash = hash_conntrack(tuple); list_for_each_entry(h, &nf_conntrack_hash[hash], list) { if (nf_ct_tuplehash_to_ctrack(h) != ignored_conntrack && nf_ct_tuple_equal(tuple, &h->tuple)) { NF_CT_STAT_INC(found); return h; } NF_CT_STAT_INC(searched); } return NULL; } EXPORT_SYMBOL_GPL(__nf_conntrack_find); /* Find a connection corresponding to a tuple. */ struct nf_conntrack_tuple_hash * nf_conntrack_find_get(const struct nf_conntrack_tuple *tuple, const struct nf_conn *ignored_conntrack) { struct nf_conntrack_tuple_hash *h; read_lock_bh(&nf_conntrack_lock); h = __nf_conntrack_find(tuple, ignored_conntrack); if (h) atomic_inc(&nf_ct_tuplehash_to_ctrack(h)->ct_general.use); read_unlock_bh(&nf_conntrack_lock); return h; } EXPORT_SYMBOL_GPL(nf_conntrack_find_get); static void __nf_conntrack_hash_insert(struct nf_conn *ct, unsigned int hash, unsigned int repl_hash) { ct->id = ++nf_conntrack_next_id; list_add(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list, &nf_conntrack_hash[hash]); list_add(&ct->tuplehash[IP_CT_DIR_REPLY].list, &nf_conntrack_hash[repl_hash]); } void nf_conntrack_hash_insert(struct nf_conn *ct) { unsigned int hash, repl_hash; hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); write_lock_bh(&nf_conntrack_lock); __nf_conntrack_hash_insert(ct, hash, repl_hash); write_unlock_bh(&nf_conntrack_lock); } EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); /* Confirm a connection given skb; places it in hash table */ int __nf_conntrack_confirm(struct sk_buff **pskb) { unsigned int hash, repl_hash; struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; struct nf_conn_help *help; enum ip_conntrack_info ctinfo; ct = nf_ct_get(*pskb, &ctinfo); /* ipt_REJECT uses nf_conntrack_attach to attach related ICMP/TCP RST packets in other direction. Actual packet which created connection will be IP_CT_NEW or for an expected connection, IP_CT_RELATED. */ if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) return NF_ACCEPT; hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); /* We're not in hash table, and we refuse to set up related connections for unconfirmed conns. But packet copies and REJECT will give spurious warnings here. */ /* NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 1); */ /* No external references means noone else could have confirmed us. */ NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); DEBUGP("Confirming conntrack %p\n", ct); write_lock_bh(&nf_conntrack_lock); /* See if there's one in the list already, including reverse: NAT could have grabbed it without realizing, since we're not in the hash. If there is, we lost race. */ list_for_each_entry(h, &nf_conntrack_hash[hash], list) if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, &h->tuple)) goto out; list_for_each_entry(h, &nf_conntrack_hash[repl_hash], list) if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple, &h->tuple)) goto out; /* Remove from unconfirmed list */ list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list); __nf_conntrack_hash_insert(ct, hash, repl_hash); /* Timer relative to confirmation time, not original setting time, otherwise we'd get timer wrap in weird delay cases. */ ct->timeout.expires += jiffies; add_timer(&ct->timeout); atomic_inc(&ct->ct_general.use); set_bit(IPS_CONFIRMED_BIT, &ct->status); NF_CT_STAT_INC(insert); write_unlock_bh(&nf_conntrack_lock); help = nfct_help(ct); if (help && help->helper) nf_conntrack_event_cache(IPCT_HELPER, *pskb); #ifdef CONFIG_NF_NAT_NEEDED if (test_bit(IPS_SRC_NAT_DONE_BIT, &ct->status) || test_bit(IPS_DST_NAT_DONE_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_NATINFO, *pskb); #endif nf_conntrack_event_cache(master_ct(ct) ? IPCT_RELATED : IPCT_NEW, *pskb); return NF_ACCEPT; out: NF_CT_STAT_INC(insert_failed); write_unlock_bh(&nf_conntrack_lock); return NF_DROP; } EXPORT_SYMBOL_GPL(__nf_conntrack_confirm); /* Returns true if a connection correspondings to the tuple (required for NAT). */ int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, const struct nf_conn *ignored_conntrack) { struct nf_conntrack_tuple_hash *h; read_lock_bh(&nf_conntrack_lock); h = __nf_conntrack_find(tuple, ignored_conntrack); read_unlock_bh(&nf_conntrack_lock); return h != NULL; } EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken); /* There's a small race here where we may free a just-assured connection. Too bad: we're in trouble anyway. */ static int early_drop(struct list_head *chain) { /* Traverse backwards: gives us oldest, which is roughly LRU */ struct nf_conntrack_tuple_hash *h; struct nf_conn *ct = NULL, *tmp; int dropped = 0; read_lock_bh(&nf_conntrack_lock); list_for_each_entry_reverse(h, chain, list) { tmp = nf_ct_tuplehash_to_ctrack(h); if (!test_bit(IPS_ASSURED_BIT, &tmp->status)) { ct = tmp; atomic_inc(&ct->ct_general.use); break; } } read_unlock_bh(&nf_conntrack_lock); if (!ct) return dropped; if (del_timer(&ct->timeout)) { death_by_timeout((unsigned long)ct); dropped = 1; NF_CT_STAT_INC_ATOMIC(early_drop); } nf_ct_put(ct); return dropped; } static struct nf_conn * __nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, const struct nf_conntrack_tuple *repl, const struct nf_conntrack_l3proto *l3proto, u_int32_t features) { struct nf_conn *conntrack = NULL; struct nf_conntrack_helper *helper; if (unlikely(!nf_conntrack_hash_rnd_initted)) { get_random_bytes(&nf_conntrack_hash_rnd, 4); nf_conntrack_hash_rnd_initted = 1; } /* We don't want any race condition at early drop stage */ atomic_inc(&nf_conntrack_count); if (nf_conntrack_max && atomic_read(&nf_conntrack_count) > nf_conntrack_max) { unsigned int hash = hash_conntrack(orig); /* Try dropping from this hash chain. */ if (!early_drop(&nf_conntrack_hash[hash])) { atomic_dec(&nf_conntrack_count); if (net_ratelimit()) printk(KERN_WARNING "nf_conntrack: table full, dropping" " packet.\n"); return ERR_PTR(-ENOMEM); } } /* find features needed by this conntrack. */ features |= l3proto->get_features(orig); /* FIXME: protect helper list per RCU */ read_lock_bh(&nf_conntrack_lock); helper = __nf_ct_helper_find(repl); /* NAT might want to assign a helper later */ if (helper || features & NF_CT_F_NAT) features |= NF_CT_F_HELP; read_unlock_bh(&nf_conntrack_lock); DEBUGP("nf_conntrack_alloc: features=0x%x\n", features); read_lock_bh(&nf_ct_cache_lock); if (unlikely(!nf_ct_cache[features].use)) { DEBUGP("nf_conntrack_alloc: not supported features = 0x%x\n", features); goto out; } conntrack = kmem_cache_alloc(nf_ct_cache[features].cachep, GFP_ATOMIC); if (conntrack == NULL) { DEBUGP("nf_conntrack_alloc: Can't alloc conntrack from cache\n"); goto out; } memset(conntrack, 0, nf_ct_cache[features].size); conntrack->features = features; atomic_set(&conntrack->ct_general.use, 1); conntrack->ct_general.destroy = destroy_conntrack; conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; /* Don't set timer yet: wait for confirmation */ init_timer(&conntrack->timeout); conntrack->timeout.data = (unsigned long)conntrack; conntrack->timeout.function = death_by_timeout; read_unlock_bh(&nf_ct_cache_lock); return conntrack; out: read_unlock_bh(&nf_ct_cache_lock); atomic_dec(&nf_conntrack_count); return conntrack; } struct nf_conn *nf_conntrack_alloc(const struct nf_conntrack_tuple *orig, const struct nf_conntrack_tuple *repl) { struct nf_conntrack_l3proto *l3proto; struct nf_conn *ct; rcu_read_lock(); l3proto = __nf_ct_l3proto_find(orig->src.l3num); ct = __nf_conntrack_alloc(orig, repl, l3proto, 0); rcu_read_unlock(); return ct; } EXPORT_SYMBOL_GPL(nf_conntrack_alloc); void nf_conntrack_free(struct nf_conn *conntrack) { u_int32_t features = conntrack->features; NF_CT_ASSERT(features >= NF_CT_F_BASIC && features < NF_CT_F_NUM); DEBUGP("nf_conntrack_free: features = 0x%x, conntrack=%p\n", features, conntrack); kmem_cache_free(nf_ct_cache[features].cachep, conntrack); atomic_dec(&nf_conntrack_count); } EXPORT_SYMBOL_GPL(nf_conntrack_free); /* Allocate a new conntrack: we return -ENOMEM if classification failed due to stress. Otherwise it really is unclassifiable. */ static struct nf_conntrack_tuple_hash * init_conntrack(const struct nf_conntrack_tuple *tuple, struct nf_conntrack_l3proto *l3proto, struct nf_conntrack_l4proto *l4proto, struct sk_buff *skb, unsigned int dataoff) { struct nf_conn *conntrack; struct nf_conntrack_tuple repl_tuple; struct nf_conntrack_expect *exp; u_int32_t features = 0; if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) { DEBUGP("Can't invert tuple.\n"); return NULL; } read_lock_bh(&nf_conntrack_lock); exp = __nf_conntrack_expect_find(tuple); if (exp && exp->helper) features = NF_CT_F_HELP; read_unlock_bh(&nf_conntrack_lock); conntrack = __nf_conntrack_alloc(tuple, &repl_tuple, l3proto, features); if (conntrack == NULL || IS_ERR(conntrack)) { DEBUGP("Can't allocate conntrack.\n"); return (struct nf_conntrack_tuple_hash *)conntrack; } if (!l4proto->new(conntrack, skb, dataoff)) { nf_conntrack_free(conntrack); DEBUGP("init conntrack: can't track with proto module\n"); return NULL; } write_lock_bh(&nf_conntrack_lock); exp = find_expectation(tuple); if (exp) { DEBUGP("conntrack: expectation arrives ct=%p exp=%p\n", conntrack, exp); /* Welcome, Mr. Bond. We've been expecting you... */ __set_bit(IPS_EXPECTED_BIT, &conntrack->status); conntrack->master = exp->master; if (exp->helper) nfct_help(conntrack)->helper = exp->helper; #ifdef CONFIG_NF_CONNTRACK_MARK conntrack->mark = exp->master->mark; #endif #ifdef CONFIG_NF_CONNTRACK_SECMARK conntrack->secmark = exp->master->secmark; #endif nf_conntrack_get(&conntrack->master->ct_general); NF_CT_STAT_INC(expect_new); } else { struct nf_conn_help *help = nfct_help(conntrack); if (help) help->helper = __nf_ct_helper_find(&repl_tuple); NF_CT_STAT_INC(new); } /* Overload tuple linked list to put us in unconfirmed list. */ list_add(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL].list, &unconfirmed); write_unlock_bh(&nf_conntrack_lock); if (exp) { if (exp->expectfn) exp->expectfn(conntrack, exp); nf_conntrack_expect_put(exp); } return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL]; } /* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ static inline struct nf_conn * resolve_normal_ct(struct sk_buff *skb, unsigned int dataoff, u_int16_t l3num, u_int8_t protonum, struct nf_conntrack_l3proto *l3proto, struct nf_conntrack_l4proto *l4proto, int *set_reply, enum ip_conntrack_info *ctinfo) { struct nf_conntrack_tuple tuple; struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; if (!nf_ct_get_tuple(skb, (unsigned int)(skb->nh.raw - skb->data), dataoff, l3num, protonum, &tuple, l3proto, l4proto)) { DEBUGP("resolve_normal_ct: Can't get tuple\n"); return NULL; } /* look for tuple match */ h = nf_conntrack_find_get(&tuple, NULL); if (!h) { h = init_conntrack(&tuple, l3proto, l4proto, skb, dataoff); if (!h) return NULL; if (IS_ERR(h)) return (void *)h; } ct = nf_ct_tuplehash_to_ctrack(h); /* It exists; we have (non-exclusive) reference. */ if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) { *ctinfo = IP_CT_ESTABLISHED + IP_CT_IS_REPLY; /* Please set reply bit if this packet OK */ *set_reply = 1; } else { /* Once we've had two way comms, always ESTABLISHED. */ if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { DEBUGP("nf_conntrack_in: normal packet for %p\n", ct); *ctinfo = IP_CT_ESTABLISHED; } else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) { DEBUGP("nf_conntrack_in: related packet for %p\n", ct); *ctinfo = IP_CT_RELATED; } else { DEBUGP("nf_conntrack_in: new packet for %p\n", ct); *ctinfo = IP_CT_NEW; } *set_reply = 0; } skb->nfct = &ct->ct_general; skb->nfctinfo = *ctinfo; return ct; } unsigned int nf_conntrack_in(int pf, unsigned int hooknum, struct sk_buff **pskb) { struct nf_conn *ct; enum ip_conntrack_info ctinfo; struct nf_conntrack_l3proto *l3proto; struct nf_conntrack_l4proto *l4proto; unsigned int dataoff; u_int8_t protonum; int set_reply = 0; int ret; /* Previously seen (loopback or untracked)? Ignore. */ if ((*pskb)->nfct) { NF_CT_STAT_INC_ATOMIC(ignore); return NF_ACCEPT; } /* rcu_read_lock()ed by nf_hook_slow */ l3proto = __nf_ct_l3proto_find((u_int16_t)pf); if ((ret = l3proto->prepare(pskb, hooknum, &dataoff, &protonum)) <= 0) { DEBUGP("not prepared to track yet or error occured\n"); return -ret; } l4proto = __nf_ct_l4proto_find((u_int16_t)pf, protonum); /* It may be an special packet, error, unclean... * inverse of the return code tells to the netfilter * core what to do with the packet. */ if (l4proto->error != NULL && (ret = l4proto->error(*pskb, dataoff, &ctinfo, pf, hooknum)) <= 0) { NF_CT_STAT_INC_ATOMIC(error); NF_CT_STAT_INC_ATOMIC(invalid); return -ret; } ct = resolve_normal_ct(*pskb, dataoff, pf, protonum, l3proto, l4proto, &set_reply, &ctinfo); if (!ct) { /* Not valid part of a connection */ NF_CT_STAT_INC_ATOMIC(invalid); return NF_ACCEPT; } if (IS_ERR(ct)) { /* Too stressed to deal. */ NF_CT_STAT_INC_ATOMIC(drop); return NF_DROP; } NF_CT_ASSERT((*pskb)->nfct); ret = l4proto->packet(ct, *pskb, dataoff, ctinfo, pf, hooknum); if (ret < 0) { /* Invalid: inverse of the return code tells * the netfilter core what to do */ DEBUGP("nf_conntrack_in: Can't track with proto module\n"); nf_conntrack_put((*pskb)->nfct); (*pskb)->nfct = NULL; NF_CT_STAT_INC_ATOMIC(invalid); return -ret; } if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_STATUS, *pskb); return ret; } EXPORT_SYMBOL_GPL(nf_conntrack_in); int nf_ct_invert_tuplepr(struct nf_conntrack_tuple *inverse, const struct nf_conntrack_tuple *orig) { int ret; rcu_read_lock(); ret = nf_ct_invert_tuple(inverse, orig, __nf_ct_l3proto_find(orig->src.l3num), __nf_ct_l4proto_find(orig->src.l3num, orig->dst.protonum)); rcu_read_unlock(); return ret; } EXPORT_SYMBOL_GPL(nf_ct_invert_tuplepr); /* Alter reply tuple (maybe alter helper). This is for NAT, and is implicitly racy: see __nf_conntrack_confirm */ void nf_conntrack_alter_reply(struct nf_conn *ct, const struct nf_conntrack_tuple *newreply) { struct nf_conn_help *help = nfct_help(ct); write_lock_bh(&nf_conntrack_lock); /* Should be unconfirmed, so not in hash table yet */ NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); DEBUGP("Altering reply tuple of %p to ", ct); NF_CT_DUMP_TUPLE(newreply); ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; if (!ct->master && help && help->expecting == 0) help->helper = __nf_ct_helper_find(newreply); write_unlock_bh(&nf_conntrack_lock); } EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */ void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo, const struct sk_buff *skb, unsigned long extra_jiffies, int do_acct) { int event = 0; NF_CT_ASSERT(ct->timeout.data == (unsigned long)ct); NF_CT_ASSERT(skb); write_lock_bh(&nf_conntrack_lock); /* Only update if this is not a fixed timeout */ if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status)) { write_unlock_bh(&nf_conntrack_lock); return; } /* If not in hash table, timer will not be active yet */ if (!nf_ct_is_confirmed(ct)) { ct->timeout.expires = extra_jiffies; event = IPCT_REFRESH; } else { unsigned long newtime = jiffies + extra_jiffies; /* Only update the timeout if the new timeout is at least HZ jiffies from the old timeout. Need del_timer for race avoidance (may already be dying). */ if (newtime - ct->timeout.expires >= HZ && del_timer(&ct->timeout)) { ct->timeout.expires = newtime; add_timer(&ct->timeout); event = IPCT_REFRESH; } } #ifdef CONFIG_NF_CT_ACCT if (do_acct) { ct->counters[CTINFO2DIR(ctinfo)].packets++; ct->counters[CTINFO2DIR(ctinfo)].bytes += skb->len - (unsigned int)(skb->nh.raw - skb->data); if ((ct->counters[CTINFO2DIR(ctinfo)].packets & 0x80000000) || (ct->counters[CTINFO2DIR(ctinfo)].bytes & 0x80000000)) event |= IPCT_COUNTER_FILLING; } #endif write_unlock_bh(&nf_conntrack_lock); /* must be unlocked when calling event cache */ if (event) nf_conntrack_event_cache(event, skb); } EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct); #if defined(CONFIG_NF_CT_NETLINK) || \ defined(CONFIG_NF_CT_NETLINK_MODULE) #include #include #include /* Generic function for tcp/udp/sctp/dccp and alike. This needs to be * in ip_conntrack_core, since we don't want the protocols to autoload * or depend on ctnetlink */ int nf_ct_port_tuple_to_nfattr(struct sk_buff *skb, const struct nf_conntrack_tuple *tuple) { NFA_PUT(skb, CTA_PROTO_SRC_PORT, sizeof(u_int16_t), &tuple->src.u.tcp.port); NFA_PUT(skb, CTA_PROTO_DST_PORT, sizeof(u_int16_t), &tuple->dst.u.tcp.port); return 0; nfattr_failure: return -1; } EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nfattr); static const size_t cta_min_proto[CTA_PROTO_MAX] = { [CTA_PROTO_SRC_PORT-1] = sizeof(u_int16_t), [CTA_PROTO_DST_PORT-1] = sizeof(u_int16_t) }; int nf_ct_port_nfattr_to_tuple(struct nfattr *tb[], struct nf_conntrack_tuple *t) { if (!tb[CTA_PROTO_SRC_PORT-1] || !tb[CTA_PROTO_DST_PORT-1]) return -EINVAL; if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto)) return -EINVAL; t->src.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_SRC_PORT-1]); t->dst.u.tcp.port = *(__be16 *)NFA_DATA(tb[CTA_PROTO_DST_PORT-1]); return 0; } EXPORT_SYMBOL_GPL(nf_ct_port_nfattr_to_tuple); #endif /* Used by ipt_REJECT and ip6t_REJECT. */ void __nf_conntrack_attach(struct sk_buff *nskb, struct sk_buff *skb) { struct nf_conn *ct; enum ip_conntrack_info ctinfo; /* This ICMP is in reverse direction to the packet which caused it */ ct = nf_ct_get(skb, &ctinfo); if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ctinfo = IP_CT_RELATED + IP_CT_IS_REPLY; else ctinfo = IP_CT_RELATED; /* Attach to new skbuff, and increment count */ nskb->nfct = &ct->ct_general; nskb->nfctinfo = ctinfo; nf_conntrack_get(nskb->nfct); } EXPORT_SYMBOL_GPL(__nf_conntrack_attach); static inline int do_iter(const struct nf_conntrack_tuple_hash *i, int (*iter)(struct nf_conn *i, void *data), void *data) { return iter(nf_ct_tuplehash_to_ctrack(i), data); } /* Bring out ya dead! */ static struct nf_conn * get_next_corpse(int (*iter)(struct nf_conn *i, void *data), void *data, unsigned int *bucket) { struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; write_lock_bh(&nf_conntrack_lock); for (; *bucket < nf_conntrack_htable_size; (*bucket)++) { list_for_each_entry(h, &nf_conntrack_hash[*bucket], list) { ct = nf_ct_tuplehash_to_ctrack(h); if (iter(ct, data)) goto found; } } list_for_each_entry(h, &unconfirmed, list) { ct = nf_ct_tuplehash_to_ctrack(h); if (iter(ct, data)) goto found; } write_unlock_bh(&nf_conntrack_lock); return NULL; found: atomic_inc(&ct->ct_general.use); write_unlock_bh(&nf_conntrack_lock); return ct; } void nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data), void *data) { struct nf_conn *ct; unsigned int bucket = 0; while ((ct = get_next_corpse(iter, data, &bucket)) != NULL) { /* Time to push up daises... */ if (del_timer(&ct->timeout)) death_by_timeout((unsigned long)ct); /* ... else the timer will get him soon. */ nf_ct_put(ct); } } EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup); static int kill_all(struct nf_conn *i, void *data) { return 1; } static void free_conntrack_hash(struct list_head *hash, int vmalloced, int size) { if (vmalloced) vfree(hash); else free_pages((unsigned long)hash, get_order(sizeof(struct list_head) * size)); } void nf_conntrack_flush(void) { nf_ct_iterate_cleanup(kill_all, NULL); } EXPORT_SYMBOL_GPL(nf_conntrack_flush); /* Mishearing the voices in his head, our hero wonders how he's supposed to kill the mall. */ void nf_conntrack_cleanup(void) { int i; rcu_assign_pointer(ip_ct_attach, NULL); /* This makes sure all current packets have passed through netfilter framework. Roll on, two-stage module delete... */ synchronize_net(); nf_ct_event_cache_flush(); i_see_dead_people: nf_conntrack_flush(); if (atomic_read(&nf_conntrack_count) != 0) { schedule(); goto i_see_dead_people; } /* wait until all references to nf_conntrack_untracked are dropped */ while (atomic_read(&nf_conntrack_untracked.ct_general.use) > 1) schedule(); for (i = 0; i < NF_CT_F_NUM; i++) { if (nf_ct_cache[i].use == 0) continue; NF_CT_ASSERT(nf_ct_cache[i].use == 1); nf_ct_cache[i].use = 1; nf_conntrack_unregister_cache(i); } kmem_cache_destroy(nf_conntrack_expect_cachep); free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc, nf_conntrack_htable_size); nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_generic); /* free l3proto protocol tables */ for (i = 0; i < PF_MAX; i++) if (nf_ct_protos[i]) { kfree(nf_ct_protos[i]); nf_ct_protos[i] = NULL; } } static struct list_head *alloc_hashtable(int size, int *vmalloced) { struct list_head *hash; unsigned int i; *vmalloced = 0; hash = (void*)__get_free_pages(GFP_KERNEL, get_order(sizeof(struct list_head) * size)); if (!hash) { *vmalloced = 1; printk(KERN_WARNING "nf_conntrack: falling back to vmalloc.\n"); hash = vmalloc(sizeof(struct list_head) * size); } if (hash) for (i = 0; i < size; i++) INIT_LIST_HEAD(&hash[i]); return hash; } int set_hashsize(const char *val, struct kernel_param *kp) { int i, bucket, hashsize, vmalloced; int old_vmalloced, old_size; int rnd; struct list_head *hash, *old_hash; struct nf_conntrack_tuple_hash *h; /* On boot, we can set this without any fancy locking. */ if (!nf_conntrack_htable_size) return param_set_uint(val, kp); hashsize = simple_strtol(val, NULL, 0); if (!hashsize) return -EINVAL; hash = alloc_hashtable(hashsize, &vmalloced); if (!hash) return -ENOMEM; /* We have to rehahs for the new table anyway, so we also can * use a newrandom seed */ get_random_bytes(&rnd, 4); write_lock_bh(&nf_conntrack_lock); for (i = 0; i < nf_conntrack_htable_size; i++) { while (!list_empty(&nf_conntrack_hash[i])) { h = list_entry(nf_conntrack_hash[i].next, struct nf_conntrack_tuple_hash, list); list_del(&h->list); bucket = __hash_conntrack(&h->tuple, hashsize, rnd); list_add_tail(&h->list, &hash[bucket]); } } old_size = nf_conntrack_htable_size; old_vmalloced = nf_conntrack_vmalloc; old_hash = nf_conntrack_hash; nf_conntrack_htable_size = hashsize; nf_conntrack_vmalloc = vmalloced; nf_conntrack_hash = hash; nf_conntrack_hash_rnd = rnd; write_unlock_bh(&nf_conntrack_lock); free_conntrack_hash(old_hash, old_vmalloced, old_size); return 0; } module_param_call(hashsize, set_hashsize, param_get_uint, &nf_conntrack_htable_size, 0600); int __init nf_conntrack_init(void) { unsigned int i; int ret; /* Idea from tcp.c: use 1/16384 of memory. On i386: 32MB * machine has 256 buckets. >= 1GB machines have 8192 buckets. */ if (!nf_conntrack_htable_size) { nf_conntrack_htable_size = (((num_physpages << PAGE_SHIFT) / 16384) / sizeof(struct list_head)); if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE)) nf_conntrack_htable_size = 8192; if (nf_conntrack_htable_size < 16) nf_conntrack_htable_size = 16; } nf_conntrack_max = 8 * nf_conntrack_htable_size; printk("nf_conntrack version %s (%u buckets, %d max)\n", NF_CONNTRACK_VERSION, nf_conntrack_htable_size, nf_conntrack_max); nf_conntrack_hash = alloc_hashtable(nf_conntrack_htable_size, &nf_conntrack_vmalloc); if (!nf_conntrack_hash) { printk(KERN_ERR "Unable to create nf_conntrack_hash\n"); goto err_out; } ret = nf_conntrack_register_cache(NF_CT_F_BASIC, "nf_conntrack:basic", sizeof(struct nf_conn)); if (ret < 0) { printk(KERN_ERR "Unable to create nf_conn slab cache\n"); goto err_free_hash; } nf_conntrack_expect_cachep = kmem_cache_create("nf_conntrack_expect", sizeof(struct nf_conntrack_expect), 0, 0, NULL, NULL); if (!nf_conntrack_expect_cachep) { printk(KERN_ERR "Unable to create nf_expect slab cache\n"); goto err_free_conntrack_slab; } ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_generic); if (ret < 0) goto out_free_expect_slab; /* Don't NEED lock here, but good form anyway. */ write_lock_bh(&nf_conntrack_lock); for (i = 0; i < AF_MAX; i++) nf_ct_l3protos[i] = &nf_conntrack_l3proto_generic; write_unlock_bh(&nf_conntrack_lock); /* For use by REJECT target */ rcu_assign_pointer(ip_ct_attach, __nf_conntrack_attach); /* Set up fake conntrack: - to never be deleted, not in any hashes */ atomic_set(&nf_conntrack_untracked.ct_general.use, 1); /* - and look it like as a confirmed connection */ set_bit(IPS_CONFIRMED_BIT, &nf_conntrack_untracked.status); return ret; out_free_expect_slab: kmem_cache_destroy(nf_conntrack_expect_cachep); err_free_conntrack_slab: nf_conntrack_unregister_cache(NF_CT_F_BASIC); err_free_hash: free_conntrack_hash(nf_conntrack_hash, nf_conntrack_vmalloc, nf_conntrack_htable_size); err_out: return -ENOMEM; }