blob: bd45f9d3f7d0b4313b3681f1f68fd584aabe3ff1 [file] [log] [blame]
/* iptables match extension to limit the number of packets per second
* seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
*
* (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
*
* $Id: ipt_hashlimit.c 3244 2004-10-20 16:24:29Z laforge@netfilter.org $
*
* Development of this code was funded by Astaro AG, http://www.astaro.com/
*/
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/random.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter/xt_hashlimit.h>
#include <linux/mutex.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("iptables match for limiting per hash-bucket");
MODULE_ALIAS("ipt_hashlimit");
MODULE_ALIAS("ip6t_hashlimit");
/* need to declare this at the top */
static struct proc_dir_entry *hashlimit_procdir4;
static struct proc_dir_entry *hashlimit_procdir6;
static const struct file_operations dl_file_ops;
/* hash table crap */
struct dsthash_dst {
union {
struct {
__be32 src;
__be32 dst;
} ip;
struct {
__be32 src[4];
__be32 dst[4];
} ip6;
} addr;
__be16 src_port;
__be16 dst_port;
};
struct dsthash_ent {
/* static / read-only parts in the beginning */
struct hlist_node node;
struct dsthash_dst dst;
/* modified structure members in the end */
unsigned long expires; /* precalculated expiry time */
struct {
unsigned long prev; /* last modification */
u_int32_t credit;
u_int32_t credit_cap, cost;
} rateinfo;
};
struct xt_hashlimit_htable {
struct hlist_node node; /* global list of all htables */
atomic_t use;
int family;
struct hashlimit_cfg cfg; /* config */
/* used internally */
spinlock_t lock; /* lock for list_head */
u_int32_t rnd; /* random seed for hash */
int rnd_initialized;
unsigned int count; /* number entries in table */
struct timer_list timer; /* timer for gc */
/* seq_file stuff */
struct proc_dir_entry *pde;
struct hlist_head hash[0]; /* hashtable itself */
};
static DEFINE_SPINLOCK(hashlimit_lock); /* protects htables list */
static DEFINE_MUTEX(hlimit_mutex); /* additional checkentry protection */
static HLIST_HEAD(hashlimit_htables);
static struct kmem_cache *hashlimit_cachep __read_mostly;
static inline bool dst_cmp(const struct dsthash_ent *ent,
const struct dsthash_dst *b)
{
return !memcmp(&ent->dst, b, sizeof(ent->dst));
}
static u_int32_t
hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst)
{
return jhash(dst, sizeof(*dst), ht->rnd) % ht->cfg.size;
}
static struct dsthash_ent *
dsthash_find(const struct xt_hashlimit_htable *ht,
const struct dsthash_dst *dst)
{
struct dsthash_ent *ent;
struct hlist_node *pos;
u_int32_t hash = hash_dst(ht, dst);
if (!hlist_empty(&ht->hash[hash])) {
hlist_for_each_entry(ent, pos, &ht->hash[hash], node)
if (dst_cmp(ent, dst))
return ent;
}
return NULL;
}
/* allocate dsthash_ent, initialize dst, put in htable and lock it */
static struct dsthash_ent *
dsthash_alloc_init(struct xt_hashlimit_htable *ht,
const struct dsthash_dst *dst)
{
struct dsthash_ent *ent;
/* initialize hash with random val at the time we allocate
* the first hashtable entry */
if (!ht->rnd_initialized) {
get_random_bytes(&ht->rnd, 4);
ht->rnd_initialized = 1;
}
if (ht->cfg.max && ht->count >= ht->cfg.max) {
/* FIXME: do something. question is what.. */
if (net_ratelimit())
printk(KERN_WARNING
"xt_hashlimit: max count of %u reached\n",
ht->cfg.max);
return NULL;
}
ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC);
if (!ent) {
if (net_ratelimit())
printk(KERN_ERR
"xt_hashlimit: can't allocate dsthash_ent\n");
return NULL;
}
memcpy(&ent->dst, dst, sizeof(ent->dst));
hlist_add_head(&ent->node, &ht->hash[hash_dst(ht, dst)]);
ht->count++;
return ent;
}
static inline void
dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent)
{
hlist_del(&ent->node);
kmem_cache_free(hashlimit_cachep, ent);
ht->count--;
}
static void htable_gc(unsigned long htlong);
static int htable_create(struct xt_hashlimit_info *minfo, int family)
{
struct xt_hashlimit_htable *hinfo;
unsigned int size;
unsigned int i;
if (minfo->cfg.size)
size = minfo->cfg.size;
else {
size = ((num_physpages << PAGE_SHIFT) / 16384) /
sizeof(struct list_head);
if (num_physpages > (1024 * 1024 * 1024 / PAGE_SIZE))
size = 8192;
if (size < 16)
size = 16;
}
/* FIXME: don't use vmalloc() here or anywhere else -HW */
hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) +
sizeof(struct list_head) * size);
if (!hinfo) {
printk(KERN_ERR "xt_hashlimit: unable to create hashtable\n");
return -1;
}
minfo->hinfo = hinfo;
/* copy match config into hashtable config */
memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg));
hinfo->cfg.size = size;
if (!hinfo->cfg.max)
hinfo->cfg.max = 8 * hinfo->cfg.size;
else if (hinfo->cfg.max < hinfo->cfg.size)
hinfo->cfg.max = hinfo->cfg.size;
for (i = 0; i < hinfo->cfg.size; i++)
INIT_HLIST_HEAD(&hinfo->hash[i]);
atomic_set(&hinfo->use, 1);
hinfo->count = 0;
hinfo->family = family;
hinfo->rnd_initialized = 0;
spin_lock_init(&hinfo->lock);
hinfo->pde = create_proc_entry(minfo->name, 0,
family == AF_INET ? hashlimit_procdir4 :
hashlimit_procdir6);
if (!hinfo->pde) {
vfree(hinfo);
return -1;
}
hinfo->pde->proc_fops = &dl_file_ops;
hinfo->pde->data = hinfo;
setup_timer(&hinfo->timer, htable_gc, (unsigned long )hinfo);
hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval);
add_timer(&hinfo->timer);
spin_lock_bh(&hashlimit_lock);
hlist_add_head(&hinfo->node, &hashlimit_htables);
spin_unlock_bh(&hashlimit_lock);
return 0;
}
static bool select_all(const struct xt_hashlimit_htable *ht,
const struct dsthash_ent *he)
{
return 1;
}
static bool select_gc(const struct xt_hashlimit_htable *ht,
const struct dsthash_ent *he)
{
return jiffies >= he->expires;
}
static void htable_selective_cleanup(struct xt_hashlimit_htable *ht,
bool (*select)(const struct xt_hashlimit_htable *ht,
const struct dsthash_ent *he))
{
unsigned int i;
/* lock hash table and iterate over it */
spin_lock_bh(&ht->lock);
for (i = 0; i < ht->cfg.size; i++) {
struct dsthash_ent *dh;
struct hlist_node *pos, *n;
hlist_for_each_entry_safe(dh, pos, n, &ht->hash[i], node) {
if ((*select)(ht, dh))
dsthash_free(ht, dh);
}
}
spin_unlock_bh(&ht->lock);
}
/* hash table garbage collector, run by timer */
static void htable_gc(unsigned long htlong)
{
struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong;
htable_selective_cleanup(ht, select_gc);
/* re-add the timer accordingly */
ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval);
add_timer(&ht->timer);
}
static void htable_destroy(struct xt_hashlimit_htable *hinfo)
{
/* remove timer, if it is pending */
if (timer_pending(&hinfo->timer))
del_timer(&hinfo->timer);
/* remove proc entry */
remove_proc_entry(hinfo->pde->name,
hinfo->family == AF_INET ? hashlimit_procdir4 :
hashlimit_procdir6);
htable_selective_cleanup(hinfo, select_all);
vfree(hinfo);
}
static struct xt_hashlimit_htable *htable_find_get(const char *name,
int family)
{
struct xt_hashlimit_htable *hinfo;
struct hlist_node *pos;
spin_lock_bh(&hashlimit_lock);
hlist_for_each_entry(hinfo, pos, &hashlimit_htables, node) {
if (!strcmp(name, hinfo->pde->name) &&
hinfo->family == family) {
atomic_inc(&hinfo->use);
spin_unlock_bh(&hashlimit_lock);
return hinfo;
}
}
spin_unlock_bh(&hashlimit_lock);
return NULL;
}
static void htable_put(struct xt_hashlimit_htable *hinfo)
{
if (atomic_dec_and_test(&hinfo->use)) {
spin_lock_bh(&hashlimit_lock);
hlist_del(&hinfo->node);
spin_unlock_bh(&hashlimit_lock);
htable_destroy(hinfo);
}
}
/* The algorithm used is the Simple Token Bucket Filter (TBF)
* see net/sched/sch_tbf.c in the linux source tree
*/
/* Rusty: This is my (non-mathematically-inclined) understanding of
this algorithm. The `average rate' in jiffies becomes your initial
amount of credit `credit' and the most credit you can ever have
`credit_cap'. The `peak rate' becomes the cost of passing the
test, `cost'.
`prev' tracks the last packet hit: you gain one credit per jiffy.
If you get credit balance more than this, the extra credit is
discarded. Every time the match passes, you lose `cost' credits;
if you don't have that many, the test fails.
See Alexey's formal explanation in net/sched/sch_tbf.c.
To get the maximum range, we multiply by this factor (ie. you get N
credits per jiffy). We want to allow a rate as low as 1 per day
(slowest userspace tool allows), which means
CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
*/
#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
/* Repeated shift and or gives us all 1s, final shift and add 1 gives
* us the power of 2 below the theoretical max, so GCC simply does a
* shift. */
#define _POW2_BELOW2(x) ((x)|((x)>>1))
#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
/* Precision saver. */
static inline u_int32_t
user2credits(u_int32_t user)
{
/* If multiplying would overflow... */
if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
/* Divide first. */
return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
}
static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
{
dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY;
if (dh->rateinfo.credit > dh->rateinfo.credit_cap)
dh->rateinfo.credit = dh->rateinfo.credit_cap;
dh->rateinfo.prev = now;
}
static int
hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
struct dsthash_dst *dst,
const struct sk_buff *skb, unsigned int protoff)
{
__be16 _ports[2], *ports;
int nexthdr;
memset(dst, 0, sizeof(*dst));
switch (hinfo->family) {
case AF_INET:
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
dst->addr.ip.dst = ip_hdr(skb)->daddr;
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
dst->addr.ip.src = ip_hdr(skb)->saddr;
if (!(hinfo->cfg.mode &
(XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
return 0;
nexthdr = ip_hdr(skb)->protocol;
break;
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
case AF_INET6:
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
memcpy(&dst->addr.ip6.dst, &ipv6_hdr(skb)->daddr,
sizeof(dst->addr.ip6.dst));
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
memcpy(&dst->addr.ip6.src, &ipv6_hdr(skb)->saddr,
sizeof(dst->addr.ip6.src));
if (!(hinfo->cfg.mode &
(XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
return 0;
nexthdr = ipv6_find_hdr(skb, &protoff, -1, NULL);
if (nexthdr < 0)
return -1;
break;
#endif
default:
BUG();
return 0;
}
switch (nexthdr) {
case IPPROTO_TCP:
case IPPROTO_UDP:
case IPPROTO_UDPLITE:
case IPPROTO_SCTP:
case IPPROTO_DCCP:
ports = skb_header_pointer(skb, protoff, sizeof(_ports),
&_ports);
break;
default:
_ports[0] = _ports[1] = 0;
ports = _ports;
break;
}
if (!ports)
return -1;
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
dst->src_port = ports[0];
if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
dst->dst_port = ports[1];
return 0;
}
static bool
hashlimit_match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
bool *hotdrop)
{
const struct xt_hashlimit_info *r =
((const struct xt_hashlimit_info *)matchinfo)->u.master;
struct xt_hashlimit_htable *hinfo = r->hinfo;
unsigned long now = jiffies;
struct dsthash_ent *dh;
struct dsthash_dst dst;
if (hashlimit_init_dst(hinfo, &dst, skb, protoff) < 0)
goto hotdrop;
spin_lock_bh(&hinfo->lock);
dh = dsthash_find(hinfo, &dst);
if (!dh) {
dh = dsthash_alloc_init(hinfo, &dst);
if (!dh) {
spin_unlock_bh(&hinfo->lock);
goto hotdrop;
}
dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
dh->rateinfo.prev = jiffies;
dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
hinfo->cfg.burst);
dh->rateinfo.credit_cap = user2credits(hinfo->cfg.avg *
hinfo->cfg.burst);
dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
} else {
/* update expiration timeout */
dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
rateinfo_recalc(dh, now);
}
if (dh->rateinfo.credit >= dh->rateinfo.cost) {
/* We're underlimit. */
dh->rateinfo.credit -= dh->rateinfo.cost;
spin_unlock_bh(&hinfo->lock);
return true;
}
spin_unlock_bh(&hinfo->lock);
/* default case: we're overlimit, thus don't match */
return false;
hotdrop:
*hotdrop = true;
return false;
}
static bool
hashlimit_checkentry(const char *tablename,
const void *inf,
const struct xt_match *match,
void *matchinfo,
unsigned int hook_mask)
{
struct xt_hashlimit_info *r = matchinfo;
/* Check for overflow. */
if (r->cfg.burst == 0 ||
user2credits(r->cfg.avg * r->cfg.burst) < user2credits(r->cfg.avg)) {
printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
r->cfg.avg, r->cfg.burst);
return false;
}
if (r->cfg.mode == 0 ||
r->cfg.mode > (XT_HASHLIMIT_HASH_DPT |
XT_HASHLIMIT_HASH_DIP |
XT_HASHLIMIT_HASH_SIP |
XT_HASHLIMIT_HASH_SPT))
return false;
if (!r->cfg.gc_interval)
return false;
if (!r->cfg.expire)
return false;
if (r->name[sizeof(r->name) - 1] != '\0')
return false;
/* This is the best we've got: We cannot release and re-grab lock,
* since checkentry() is called before x_tables.c grabs xt_mutex.
* We also cannot grab the hashtable spinlock, since htable_create will
* call vmalloc, and that can sleep. And we cannot just re-search
* the list of htable's in htable_create(), since then we would
* create duplicate proc files. -HW */
mutex_lock(&hlimit_mutex);
r->hinfo = htable_find_get(r->name, match->family);
if (!r->hinfo && htable_create(r, match->family) != 0) {
mutex_unlock(&hlimit_mutex);
return false;
}
mutex_unlock(&hlimit_mutex);
/* Ugly hack: For SMP, we only want to use one set */
r->u.master = r;
return true;
}
static void
hashlimit_destroy(const struct xt_match *match, void *matchinfo)
{
const struct xt_hashlimit_info *r = matchinfo;
htable_put(r->hinfo);
}
#ifdef CONFIG_COMPAT
struct compat_xt_hashlimit_info {
char name[IFNAMSIZ];
struct hashlimit_cfg cfg;
compat_uptr_t hinfo;
compat_uptr_t master;
};
static void compat_from_user(void *dst, void *src)
{
int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
memcpy(dst, src, off);
memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
}
static int compat_to_user(void __user *dst, void *src)
{
int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
return copy_to_user(dst, src, off) ? -EFAULT : 0;
}
#endif
static struct xt_match xt_hashlimit[] __read_mostly = {
{
.name = "hashlimit",
.family = AF_INET,
.match = hashlimit_match,
.matchsize = sizeof(struct xt_hashlimit_info),
#ifdef CONFIG_COMPAT
.compatsize = sizeof(struct compat_xt_hashlimit_info),
.compat_from_user = compat_from_user,
.compat_to_user = compat_to_user,
#endif
.checkentry = hashlimit_checkentry,
.destroy = hashlimit_destroy,
.me = THIS_MODULE
},
{
.name = "hashlimit",
.family = AF_INET6,
.match = hashlimit_match,
.matchsize = sizeof(struct xt_hashlimit_info),
#ifdef CONFIG_COMPAT
.compatsize = sizeof(struct compat_xt_hashlimit_info),
.compat_from_user = compat_from_user,
.compat_to_user = compat_to_user,
#endif
.checkentry = hashlimit_checkentry,
.destroy = hashlimit_destroy,
.me = THIS_MODULE
},
};
/* PROC stuff */
static void *dl_seq_start(struct seq_file *s, loff_t *pos)
{
struct proc_dir_entry *pde = s->private;
struct xt_hashlimit_htable *htable = pde->data;
unsigned int *bucket;
spin_lock_bh(&htable->lock);
if (*pos >= htable->cfg.size)
return NULL;
bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
if (!bucket)
return ERR_PTR(-ENOMEM);
*bucket = *pos;
return bucket;
}
static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
struct proc_dir_entry *pde = s->private;
struct xt_hashlimit_htable *htable = pde->data;
unsigned int *bucket = (unsigned int *)v;
*pos = ++(*bucket);
if (*pos >= htable->cfg.size) {
kfree(v);
return NULL;
}
return bucket;
}
static void dl_seq_stop(struct seq_file *s, void *v)
{
struct proc_dir_entry *pde = s->private;
struct xt_hashlimit_htable *htable = pde->data;
unsigned int *bucket = (unsigned int *)v;
kfree(bucket);
spin_unlock_bh(&htable->lock);
}
static int dl_seq_real_show(struct dsthash_ent *ent, int family,
struct seq_file *s)
{
/* recalculate to show accurate numbers */
rateinfo_recalc(ent, jiffies);
switch (family) {
case AF_INET:
return seq_printf(s, "%ld %u.%u.%u.%u:%u->"
"%u.%u.%u.%u:%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
NIPQUAD(ent->dst.addr.ip.src),
ntohs(ent->dst.src_port),
NIPQUAD(ent->dst.addr.ip.dst),
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);
case AF_INET6:
return seq_printf(s, "%ld " NIP6_FMT ":%u->"
NIP6_FMT ":%u %u %u %u\n",
(long)(ent->expires - jiffies)/HZ,
NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.src),
ntohs(ent->dst.src_port),
NIP6(*(struct in6_addr *)&ent->dst.addr.ip6.dst),
ntohs(ent->dst.dst_port),
ent->rateinfo.credit, ent->rateinfo.credit_cap,
ent->rateinfo.cost);
default:
BUG();
return 0;
}
}
static int dl_seq_show(struct seq_file *s, void *v)
{
struct proc_dir_entry *pde = s->private;
struct xt_hashlimit_htable *htable = pde->data;
unsigned int *bucket = (unsigned int *)v;
struct dsthash_ent *ent;
struct hlist_node *pos;
if (!hlist_empty(&htable->hash[*bucket])) {
hlist_for_each_entry(ent, pos, &htable->hash[*bucket], node)
if (dl_seq_real_show(ent, htable->family, s))
return 1;
}
return 0;
}
static const struct seq_operations dl_seq_ops = {
.start = dl_seq_start,
.next = dl_seq_next,
.stop = dl_seq_stop,
.show = dl_seq_show
};
static int dl_proc_open(struct inode *inode, struct file *file)
{
int ret = seq_open(file, &dl_seq_ops);
if (!ret) {
struct seq_file *sf = file->private_data;
sf->private = PDE(inode);
}
return ret;
}
static const struct file_operations dl_file_ops = {
.owner = THIS_MODULE,
.open = dl_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release
};
static int __init xt_hashlimit_init(void)
{
int err;
err = xt_register_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
if (err < 0)
goto err1;
err = -ENOMEM;
hashlimit_cachep = kmem_cache_create("xt_hashlimit",
sizeof(struct dsthash_ent), 0, 0,
NULL);
if (!hashlimit_cachep) {
printk(KERN_ERR "xt_hashlimit: unable to create slab cache\n");
goto err2;
}
hashlimit_procdir4 = proc_mkdir("ipt_hashlimit", proc_net);
if (!hashlimit_procdir4) {
printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
"entry\n");
goto err3;
}
hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", proc_net);
if (!hashlimit_procdir6) {
printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
"entry\n");
goto err4;
}
return 0;
err4:
remove_proc_entry("ipt_hashlimit", proc_net);
err3:
kmem_cache_destroy(hashlimit_cachep);
err2:
xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
err1:
return err;
}
static void __exit xt_hashlimit_fini(void)
{
remove_proc_entry("ipt_hashlimit", proc_net);
remove_proc_entry("ip6t_hashlimit", proc_net);
kmem_cache_destroy(hashlimit_cachep);
xt_unregister_matches(xt_hashlimit, ARRAY_SIZE(xt_hashlimit));
}
module_init(xt_hashlimit_init);
module_exit(xt_hashlimit_fini);