forked from amir73il/linux
/
ip_conntrack_core.c
1482 lines (1262 loc) · 41.3 KB
/
ip_conntrack_core.c
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/* 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) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* 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 <laforge@gnumonks.org>
* - new API and handling of conntrack/nat helpers
* - now capable of multiple expectations for one master
* 16 Jul 2002: Harald Welte <laforge@gnumonks.org>
* - add usage/reference counts to ip_conntrack_expect
* - export ip_conntrack[_expect]_{find_get,put} functions
* */
#include <linux/config.h>
#include <linux/types.h>
#include <linux/icmp.h>
#include <linux/ip.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/vmalloc.h>
#include <net/checksum.h>
#include <net/ip.h>
#include <linux/stddef.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/err.h>
#include <linux/percpu.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
/* ip_conntrack_lock protects the main hash table, protocol/helper/expected
registrations, conntrack timers*/
#define ASSERT_READ_LOCK(x)
#define ASSERT_WRITE_LOCK(x)
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_conntrack_core.h>
#include <linux/netfilter_ipv4/listhelp.h>
#define IP_CONNTRACK_VERSION "2.3"
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
DEFINE_RWLOCK(ip_conntrack_lock);
/* ip_conntrack_standalone needs this */
atomic_t ip_conntrack_count = ATOMIC_INIT(0);
void (*ip_conntrack_destroyed)(struct ip_conntrack *conntrack) = NULL;
LIST_HEAD(ip_conntrack_expect_list);
struct ip_conntrack_protocol *ip_ct_protos[MAX_IP_CT_PROTO];
static LIST_HEAD(helpers);
unsigned int ip_conntrack_htable_size = 0;
int ip_conntrack_max;
struct list_head *ip_conntrack_hash;
static kmem_cache_t *ip_conntrack_cachep __read_mostly;
static kmem_cache_t *ip_conntrack_expect_cachep __read_mostly;
struct ip_conntrack ip_conntrack_untracked;
unsigned int ip_ct_log_invalid;
static LIST_HEAD(unconfirmed);
static int ip_conntrack_vmalloc;
static unsigned int ip_conntrack_next_id = 1;
static unsigned int ip_conntrack_expect_next_id = 1;
#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);
/* deliver cached events and clear cache entry - must be called with locally
* disabled softirqs */
static inline void
__ip_ct_deliver_cached_events(struct ip_conntrack_ecache *ecache)
{
DEBUGP("ecache: delivering events for %p\n", ecache->ct);
if (is_confirmed(ecache->ct) && !is_dying(ecache->ct) && ecache->events)
notifier_call_chain(&ip_conntrack_chain, ecache->events,
ecache->ct);
ecache->events = 0;
ip_conntrack_put(ecache->ct);
ecache->ct = NULL;
}
/* Deliver all cached events for a particular conntrack. This is called
* by code prior to async packet handling or freeing the skb */
void ip_ct_deliver_cached_events(const struct ip_conntrack *ct)
{
struct ip_conntrack_ecache *ecache;
local_bh_disable();
ecache = &__get_cpu_var(ip_conntrack_ecache);
if (ecache->ct == ct)
__ip_ct_deliver_cached_events(ecache);
local_bh_enable();
}
void __ip_ct_event_cache_init(struct ip_conntrack *ct)
{
struct ip_conntrack_ecache *ecache;
/* take care of delivering potentially old events */
ecache = &__get_cpu_var(ip_conntrack_ecache);
BUG_ON(ecache->ct == ct);
if (ecache->ct)
__ip_ct_deliver_cached_events(ecache);
/* initialize for this conntrack/packet */
ecache->ct = ct;
nf_conntrack_get(&ct->ct_general);
}
/* flush the event cache - touches other CPU's data and must not be called while
* packets are still passing through the code */
static void ip_ct_event_cache_flush(void)
{
struct ip_conntrack_ecache *ecache;
int cpu;
for_each_cpu(cpu) {
ecache = &per_cpu(ip_conntrack_ecache, cpu);
if (ecache->ct)
ip_conntrack_put(ecache->ct);
}
}
#else
static inline void ip_ct_event_cache_flush(void) {}
#endif /* CONFIG_IP_NF_CONNTRACK_EVENTS */
DEFINE_PER_CPU(struct ip_conntrack_stat, ip_conntrack_stat);
static int ip_conntrack_hash_rnd_initted;
static unsigned int ip_conntrack_hash_rnd;
static u_int32_t
hash_conntrack(const struct ip_conntrack_tuple *tuple)
{
#if 0
dump_tuple(tuple);
#endif
return (jhash_3words(tuple->src.ip,
(tuple->dst.ip ^ tuple->dst.protonum),
(tuple->src.u.all | (tuple->dst.u.all << 16)),
ip_conntrack_hash_rnd) % ip_conntrack_htable_size);
}
int
ip_ct_get_tuple(const struct iphdr *iph,
const struct sk_buff *skb,
unsigned int dataoff,
struct ip_conntrack_tuple *tuple,
const struct ip_conntrack_protocol *protocol)
{
/* Never happen */
if (iph->frag_off & htons(IP_OFFSET)) {
printk("ip_conntrack_core: Frag of proto %u.\n",
iph->protocol);
return 0;
}
tuple->src.ip = iph->saddr;
tuple->dst.ip = iph->daddr;
tuple->dst.protonum = iph->protocol;
tuple->dst.dir = IP_CT_DIR_ORIGINAL;
return protocol->pkt_to_tuple(skb, dataoff, tuple);
}
int
ip_ct_invert_tuple(struct ip_conntrack_tuple *inverse,
const struct ip_conntrack_tuple *orig,
const struct ip_conntrack_protocol *protocol)
{
inverse->src.ip = orig->dst.ip;
inverse->dst.ip = orig->src.ip;
inverse->dst.protonum = orig->dst.protonum;
inverse->dst.dir = !orig->dst.dir;
return protocol->invert_tuple(inverse, orig);
}
/* ip_conntrack_expect helper functions */
void ip_ct_unlink_expect(struct ip_conntrack_expect *exp)
{
ASSERT_WRITE_LOCK(&ip_conntrack_lock);
IP_NF_ASSERT(!timer_pending(&exp->timeout));
list_del(&exp->list);
CONNTRACK_STAT_INC(expect_delete);
exp->master->expecting--;
ip_conntrack_expect_put(exp);
}
static void expectation_timed_out(unsigned long ul_expect)
{
struct ip_conntrack_expect *exp = (void *)ul_expect;
write_lock_bh(&ip_conntrack_lock);
ip_ct_unlink_expect(exp);
write_unlock_bh(&ip_conntrack_lock);
ip_conntrack_expect_put(exp);
}
struct ip_conntrack_expect *
__ip_conntrack_expect_find(const struct ip_conntrack_tuple *tuple)
{
struct ip_conntrack_expect *i;
list_for_each_entry(i, &ip_conntrack_expect_list, list) {
if (ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) {
atomic_inc(&i->use);
return i;
}
}
return NULL;
}
/* Just find a expectation corresponding to a tuple. */
struct ip_conntrack_expect *
ip_conntrack_expect_find(const struct ip_conntrack_tuple *tuple)
{
struct ip_conntrack_expect *i;
read_lock_bh(&ip_conntrack_lock);
i = __ip_conntrack_expect_find(tuple);
read_unlock_bh(&ip_conntrack_lock);
return i;
}
/* If an expectation for this connection is found, it gets delete from
* global list then returned. */
static struct ip_conntrack_expect *
find_expectation(const struct ip_conntrack_tuple *tuple)
{
struct ip_conntrack_expect *i;
list_for_each_entry(i, &ip_conntrack_expect_list, list) {
/* If master is not in hash table yet (ie. packet hasn't left
this machine yet), how can other end know about expected?
Hence these are not the droids you are looking for (if
master ct never got confirmed, we'd hold a reference to it
and weird things would happen to future packets). */
if (ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)
&& is_confirmed(i->master)) {
if (i->flags & IP_CT_EXPECT_PERMANENT) {
atomic_inc(&i->use);
return i;
} else if (del_timer(&i->timeout)) {
ip_ct_unlink_expect(i);
return i;
}
}
}
return NULL;
}
/* delete all expectations for this conntrack */
void ip_ct_remove_expectations(struct ip_conntrack *ct)
{
struct ip_conntrack_expect *i, *tmp;
/* Optimization: most connection never expect any others. */
if (ct->expecting == 0)
return;
list_for_each_entry_safe(i, tmp, &ip_conntrack_expect_list, list) {
if (i->master == ct && del_timer(&i->timeout)) {
ip_ct_unlink_expect(i);
ip_conntrack_expect_put(i);
}
}
}
static void
clean_from_lists(struct ip_conntrack *ct)
{
unsigned int ho, hr;
DEBUGP("clean_from_lists(%p)\n", ct);
ASSERT_WRITE_LOCK(&ip_conntrack_lock);
ho = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
hr = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
LIST_DELETE(&ip_conntrack_hash[ho], &ct->tuplehash[IP_CT_DIR_ORIGINAL]);
LIST_DELETE(&ip_conntrack_hash[hr], &ct->tuplehash[IP_CT_DIR_REPLY]);
/* Destroy all pending expectations */
ip_ct_remove_expectations(ct);
}
static void
destroy_conntrack(struct nf_conntrack *nfct)
{
struct ip_conntrack *ct = (struct ip_conntrack *)nfct;
struct ip_conntrack_protocol *proto;
DEBUGP("destroy_conntrack(%p)\n", ct);
IP_NF_ASSERT(atomic_read(&nfct->use) == 0);
IP_NF_ASSERT(!timer_pending(&ct->timeout));
ip_conntrack_event(IPCT_DESTROY, ct);
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 */
proto = __ip_conntrack_proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
if (proto && proto->destroy)
proto->destroy(ct);
if (ip_conntrack_destroyed)
ip_conntrack_destroyed(ct);
write_lock_bh(&ip_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. */
ip_ct_remove_expectations(ct);
/* We overload first tuple to link into unconfirmed list. */
if (!is_confirmed(ct)) {
BUG_ON(list_empty(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list));
list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list);
}
CONNTRACK_STAT_INC(delete);
write_unlock_bh(&ip_conntrack_lock);
if (ct->master)
ip_conntrack_put(ct->master);
DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct);
ip_conntrack_free(ct);
}
static void death_by_timeout(unsigned long ul_conntrack)
{
struct ip_conntrack *ct = (void *)ul_conntrack;
write_lock_bh(&ip_conntrack_lock);
/* Inside lock so preempt is disabled on module removal path.
* Otherwise we can get spurious warnings. */
CONNTRACK_STAT_INC(delete_list);
clean_from_lists(ct);
write_unlock_bh(&ip_conntrack_lock);
ip_conntrack_put(ct);
}
static inline int
conntrack_tuple_cmp(const struct ip_conntrack_tuple_hash *i,
const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
ASSERT_READ_LOCK(&ip_conntrack_lock);
return tuplehash_to_ctrack(i) != ignored_conntrack
&& ip_ct_tuple_equal(tuple, &i->tuple);
}
struct ip_conntrack_tuple_hash *
__ip_conntrack_find(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
unsigned int hash = hash_conntrack(tuple);
ASSERT_READ_LOCK(&ip_conntrack_lock);
list_for_each_entry(h, &ip_conntrack_hash[hash], list) {
if (conntrack_tuple_cmp(h, tuple, ignored_conntrack)) {
CONNTRACK_STAT_INC(found);
return h;
}
CONNTRACK_STAT_INC(searched);
}
return NULL;
}
/* Find a connection corresponding to a tuple. */
struct ip_conntrack_tuple_hash *
ip_conntrack_find_get(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
read_lock_bh(&ip_conntrack_lock);
h = __ip_conntrack_find(tuple, ignored_conntrack);
if (h)
atomic_inc(&tuplehash_to_ctrack(h)->ct_general.use);
read_unlock_bh(&ip_conntrack_lock);
return h;
}
static void __ip_conntrack_hash_insert(struct ip_conntrack *ct,
unsigned int hash,
unsigned int repl_hash)
{
ct->id = ++ip_conntrack_next_id;
list_prepend(&ip_conntrack_hash[hash],
&ct->tuplehash[IP_CT_DIR_ORIGINAL].list);
list_prepend(&ip_conntrack_hash[repl_hash],
&ct->tuplehash[IP_CT_DIR_REPLY].list);
}
void ip_conntrack_hash_insert(struct ip_conntrack *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(&ip_conntrack_lock);
__ip_conntrack_hash_insert(ct, hash, repl_hash);
write_unlock_bh(&ip_conntrack_lock);
}
/* Confirm a connection given skb; places it in hash table */
int
__ip_conntrack_confirm(struct sk_buff **pskb)
{
unsigned int hash, repl_hash;
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
ct = ip_conntrack_get(*pskb, &ctinfo);
/* ipt_REJECT uses ip_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. */
/* IP_NF_ASSERT(atomic_read(&ct->ct_general.use) == 1); */
/* No external references means noone else could have
confirmed us. */
IP_NF_ASSERT(!is_confirmed(ct));
DEBUGP("Confirming conntrack %p\n", ct);
write_lock_bh(&ip_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. */
if (!LIST_FIND(&ip_conntrack_hash[hash],
conntrack_tuple_cmp,
struct ip_conntrack_tuple_hash *,
&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, NULL)
&& !LIST_FIND(&ip_conntrack_hash[repl_hash],
conntrack_tuple_cmp,
struct ip_conntrack_tuple_hash *,
&ct->tuplehash[IP_CT_DIR_REPLY].tuple, NULL)) {
/* Remove from unconfirmed list */
list_del(&ct->tuplehash[IP_CT_DIR_ORIGINAL].list);
__ip_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);
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;
}
CONNTRACK_STAT_INC(insert_failed);
write_unlock_bh(&ip_conntrack_lock);
return NF_DROP;
}
/* Returns true if a connection correspondings to the tuple (required
for NAT). */
int
ip_conntrack_tuple_taken(const struct ip_conntrack_tuple *tuple,
const struct ip_conntrack *ignored_conntrack)
{
struct ip_conntrack_tuple_hash *h;
read_lock_bh(&ip_conntrack_lock);
h = __ip_conntrack_find(tuple, ignored_conntrack);
read_unlock_bh(&ip_conntrack_lock);
return h != NULL;
}
/* There's a small race here where we may free a just-assured
connection. Too bad: we're in trouble anyway. */
static inline int unreplied(const struct ip_conntrack_tuple_hash *i)
{
return !(test_bit(IPS_ASSURED_BIT, &tuplehash_to_ctrack(i)->status));
}
static int early_drop(struct list_head *chain)
{
/* Traverse backwards: gives us oldest, which is roughly LRU */
struct ip_conntrack_tuple_hash *h;
struct ip_conntrack *ct = NULL;
int dropped = 0;
read_lock_bh(&ip_conntrack_lock);
h = LIST_FIND_B(chain, unreplied, struct ip_conntrack_tuple_hash *);
if (h) {
ct = tuplehash_to_ctrack(h);
atomic_inc(&ct->ct_general.use);
}
read_unlock_bh(&ip_conntrack_lock);
if (!ct)
return dropped;
if (del_timer(&ct->timeout)) {
death_by_timeout((unsigned long)ct);
dropped = 1;
CONNTRACK_STAT_INC(early_drop);
}
ip_conntrack_put(ct);
return dropped;
}
static inline int helper_cmp(const struct ip_conntrack_helper *i,
const struct ip_conntrack_tuple *rtuple)
{
return ip_ct_tuple_mask_cmp(rtuple, &i->tuple, &i->mask);
}
static struct ip_conntrack_helper *
__ip_conntrack_helper_find( const struct ip_conntrack_tuple *tuple)
{
return LIST_FIND(&helpers, helper_cmp,
struct ip_conntrack_helper *,
tuple);
}
struct ip_conntrack_helper *
ip_conntrack_helper_find_get( const struct ip_conntrack_tuple *tuple)
{
struct ip_conntrack_helper *helper;
/* need ip_conntrack_lock to assure that helper exists until
* try_module_get() is called */
read_lock_bh(&ip_conntrack_lock);
helper = __ip_conntrack_helper_find(tuple);
if (helper) {
/* need to increase module usage count to assure helper will
* not go away while the caller is e.g. busy putting a
* conntrack in the hash that uses the helper */
if (!try_module_get(helper->me))
helper = NULL;
}
read_unlock_bh(&ip_conntrack_lock);
return helper;
}
void ip_conntrack_helper_put(struct ip_conntrack_helper *helper)
{
module_put(helper->me);
}
struct ip_conntrack_protocol *
__ip_conntrack_proto_find(u_int8_t protocol)
{
return ip_ct_protos[protocol];
}
/* this is guaranteed to always return a valid protocol helper, since
* it falls back to generic_protocol */
struct ip_conntrack_protocol *
ip_conntrack_proto_find_get(u_int8_t protocol)
{
struct ip_conntrack_protocol *p;
preempt_disable();
p = __ip_conntrack_proto_find(protocol);
if (p) {
if (!try_module_get(p->me))
p = &ip_conntrack_generic_protocol;
}
preempt_enable();
return p;
}
void ip_conntrack_proto_put(struct ip_conntrack_protocol *p)
{
module_put(p->me);
}
struct ip_conntrack *ip_conntrack_alloc(struct ip_conntrack_tuple *orig,
struct ip_conntrack_tuple *repl)
{
struct ip_conntrack *conntrack;
if (!ip_conntrack_hash_rnd_initted) {
get_random_bytes(&ip_conntrack_hash_rnd, 4);
ip_conntrack_hash_rnd_initted = 1;
}
if (ip_conntrack_max
&& atomic_read(&ip_conntrack_count) >= ip_conntrack_max) {
unsigned int hash = hash_conntrack(orig);
/* Try dropping from this hash chain. */
if (!early_drop(&ip_conntrack_hash[hash])) {
if (net_ratelimit())
printk(KERN_WARNING
"ip_conntrack: table full, dropping"
" packet.\n");
return ERR_PTR(-ENOMEM);
}
}
conntrack = kmem_cache_alloc(ip_conntrack_cachep, GFP_ATOMIC);
if (!conntrack) {
DEBUGP("Can't allocate conntrack.\n");
return ERR_PTR(-ENOMEM);
}
memset(conntrack, 0, sizeof(*conntrack));
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;
atomic_inc(&ip_conntrack_count);
return conntrack;
}
void
ip_conntrack_free(struct ip_conntrack *conntrack)
{
atomic_dec(&ip_conntrack_count);
kmem_cache_free(ip_conntrack_cachep, conntrack);
}
/* Allocate a new conntrack: we return -ENOMEM if classification
* failed due to stress. Otherwise it really is unclassifiable */
static struct ip_conntrack_tuple_hash *
init_conntrack(struct ip_conntrack_tuple *tuple,
struct ip_conntrack_protocol *protocol,
struct sk_buff *skb)
{
struct ip_conntrack *conntrack;
struct ip_conntrack_tuple repl_tuple;
struct ip_conntrack_expect *exp;
if (!ip_ct_invert_tuple(&repl_tuple, tuple, protocol)) {
DEBUGP("Can't invert tuple.\n");
return NULL;
}
conntrack = ip_conntrack_alloc(tuple, &repl_tuple);
if (conntrack == NULL || IS_ERR(conntrack))
return (struct ip_conntrack_tuple_hash *)conntrack;
if (!protocol->new(conntrack, skb)) {
ip_conntrack_free(conntrack);
return NULL;
}
write_lock_bh(&ip_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;
#ifdef CONFIG_IP_NF_CONNTRACK_MARK
conntrack->mark = exp->master->mark;
#endif
#if defined(CONFIG_IP_NF_TARGET_MASQUERADE) || \
defined(CONFIG_IP_NF_TARGET_MASQUERADE_MODULE)
/* this is ugly, but there is no other place where to put it */
conntrack->nat.masq_index = exp->master->nat.masq_index;
#endif
nf_conntrack_get(&conntrack->master->ct_general);
CONNTRACK_STAT_INC(expect_new);
} else {
conntrack->helper = __ip_conntrack_helper_find(&repl_tuple);
CONNTRACK_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(&ip_conntrack_lock);
if (exp) {
if (exp->expectfn)
exp->expectfn(conntrack, exp);
ip_conntrack_expect_put(exp);
}
return &conntrack->tuplehash[IP_CT_DIR_ORIGINAL];
}
/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
static inline struct ip_conntrack *
resolve_normal_ct(struct sk_buff *skb,
struct ip_conntrack_protocol *proto,
int *set_reply,
unsigned int hooknum,
enum ip_conntrack_info *ctinfo)
{
struct ip_conntrack_tuple tuple;
struct ip_conntrack_tuple_hash *h;
struct ip_conntrack *ct;
IP_NF_ASSERT((skb->nh.iph->frag_off & htons(IP_OFFSET)) == 0);
if (!ip_ct_get_tuple(skb->nh.iph, skb, skb->nh.iph->ihl*4,
&tuple,proto))
return NULL;
/* look for tuple match */
h = ip_conntrack_find_get(&tuple, NULL);
if (!h) {
h = init_conntrack(&tuple, proto, skb);
if (!h)
return NULL;
if (IS_ERR(h))
return (void *)h;
}
ct = tuplehash_to_ctrack(h);
/* It exists; we have (non-exclusive) reference. */
if (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("ip_conntrack_in: normal packet for %p\n",
ct);
*ctinfo = IP_CT_ESTABLISHED;
} else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) {
DEBUGP("ip_conntrack_in: related packet for %p\n",
ct);
*ctinfo = IP_CT_RELATED;
} else {
DEBUGP("ip_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;
}
/* Netfilter hook itself. */
unsigned int ip_conntrack_in(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
struct ip_conntrack_protocol *proto;
int set_reply = 0;
int ret;
/* Previously seen (loopback or untracked)? Ignore. */
if ((*pskb)->nfct) {
CONNTRACK_STAT_INC(ignore);
return NF_ACCEPT;
}
/* Never happen */
if ((*pskb)->nh.iph->frag_off & htons(IP_OFFSET)) {
if (net_ratelimit()) {
printk(KERN_ERR "ip_conntrack_in: Frag of proto %u (hook=%u)\n",
(*pskb)->nh.iph->protocol, hooknum);
}
return NF_DROP;
}
/* Doesn't cover locally-generated broadcast, so not worth it. */
#if 0
/* Ignore broadcast: no `connection'. */
if ((*pskb)->pkt_type == PACKET_BROADCAST) {
printk("Broadcast packet!\n");
return NF_ACCEPT;
} else if (((*pskb)->nh.iph->daddr & htonl(0x000000FF))
== htonl(0x000000FF)) {
printk("Should bcast: %u.%u.%u.%u->%u.%u.%u.%u (sk=%p, ptype=%u)\n",
NIPQUAD((*pskb)->nh.iph->saddr),
NIPQUAD((*pskb)->nh.iph->daddr),
(*pskb)->sk, (*pskb)->pkt_type);
}
#endif
proto = __ip_conntrack_proto_find((*pskb)->nh.iph->protocol);
/* 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 (proto->error != NULL
&& (ret = proto->error(*pskb, &ctinfo, hooknum)) <= 0) {
CONNTRACK_STAT_INC(error);
CONNTRACK_STAT_INC(invalid);
return -ret;
}
if (!(ct = resolve_normal_ct(*pskb, proto,&set_reply,hooknum,&ctinfo))) {
/* Not valid part of a connection */
CONNTRACK_STAT_INC(invalid);
return NF_ACCEPT;
}
if (IS_ERR(ct)) {
/* Too stressed to deal. */
CONNTRACK_STAT_INC(drop);
return NF_DROP;
}
IP_NF_ASSERT((*pskb)->nfct);
ret = proto->packet(ct, *pskb, ctinfo);
if (ret < 0) {
/* Invalid: inverse of the return code tells
* the netfilter core what to do*/
nf_conntrack_put((*pskb)->nfct);
(*pskb)->nfct = NULL;
CONNTRACK_STAT_INC(invalid);
return -ret;
}
if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
ip_conntrack_event_cache(IPCT_STATUS, *pskb);
return ret;
}
int invert_tuplepr(struct ip_conntrack_tuple *inverse,
const struct ip_conntrack_tuple *orig)
{
return ip_ct_invert_tuple(inverse, orig,
__ip_conntrack_proto_find(orig->dst.protonum));
}
/* Would two expected things clash? */
static inline int expect_clash(const struct ip_conntrack_expect *a,
const struct ip_conntrack_expect *b)
{
/* Part covered by intersection of masks must be unequal,
otherwise they clash */
struct ip_conntrack_tuple intersect_mask
= { { a->mask.src.ip & b->mask.src.ip,
{ a->mask.src.u.all & b->mask.src.u.all } },
{ a->mask.dst.ip & b->mask.dst.ip,
{ a->mask.dst.u.all & b->mask.dst.u.all },
a->mask.dst.protonum & b->mask.dst.protonum } };
return ip_ct_tuple_mask_cmp(&a->tuple, &b->tuple, &intersect_mask);
}
static inline int expect_matches(const struct ip_conntrack_expect *a,
const struct ip_conntrack_expect *b)
{
return a->master == b->master
&& ip_ct_tuple_equal(&a->tuple, &b->tuple)
&& ip_ct_tuple_equal(&a->mask, &b->mask);
}
/* Generally a bad idea to call this: could have matched already. */
void ip_conntrack_unexpect_related(struct ip_conntrack_expect *exp)
{
struct ip_conntrack_expect *i;
write_lock_bh(&ip_conntrack_lock);
/* choose the the oldest expectation to evict */
list_for_each_entry_reverse(i, &ip_conntrack_expect_list, list) {
if (expect_matches(i, exp) && del_timer(&i->timeout)) {
ip_ct_unlink_expect(i);
write_unlock_bh(&ip_conntrack_lock);
ip_conntrack_expect_put(i);
return;
}
}
write_unlock_bh(&ip_conntrack_lock);
}
/* We don't increase the master conntrack refcount for non-fulfilled
* conntracks. During the conntrack destruction, the expectations are
* always killed before the conntrack itself */
struct ip_conntrack_expect *ip_conntrack_expect_alloc(struct ip_conntrack *me)
{
struct ip_conntrack_expect *new;
new = kmem_cache_alloc(ip_conntrack_expect_cachep, GFP_ATOMIC);
if (!new) {
DEBUGP("expect_related: OOM allocating expect\n");
return NULL;
}
new->master = me;
atomic_set(&new->use, 1);
return new;
}
void ip_conntrack_expect_put(struct ip_conntrack_expect *exp)
{
if (atomic_dec_and_test(&exp->use))
kmem_cache_free(ip_conntrack_expect_cachep, exp);
}
static void ip_conntrack_expect_insert(struct ip_conntrack_expect *exp)
{
atomic_inc(&exp->use);
exp->master->expecting++;
list_add(&exp->list, &ip_conntrack_expect_list);
init_timer(&exp->timeout);
exp->timeout.data = (unsigned long)exp;
exp->timeout.function = expectation_timed_out;
exp->timeout.expires = jiffies + exp->master->helper->timeout * HZ;
add_timer(&exp->timeout);
exp->id = ++ip_conntrack_expect_next_id;
atomic_inc(&exp->use);
CONNTRACK_STAT_INC(expect_create);
}
/* Race with expectations being used means we could have none to find; OK. */
static void evict_oldest_expect(struct ip_conntrack *master)
{
struct ip_conntrack_expect *i;
list_for_each_entry_reverse(i, &ip_conntrack_expect_list, list) {
if (i->master == master) {
if (del_timer(&i->timeout)) {
ip_ct_unlink_expect(i);
ip_conntrack_expect_put(i);
}
break;
}
}
}
static inline int refresh_timer(struct ip_conntrack_expect *i)
{
if (!del_timer(&i->timeout))
return 0;
i->timeout.expires = jiffies + i->master->helper->timeout*HZ;
add_timer(&i->timeout);
return 1;
}