ClabureDB: Classified Bug-Reports Database

   /*
    *        xt_hashlimit - Netfilter module to limit the number of packets per time
    *        seperately for each hashbucket (sourceip/sourceport/dstip/dstport)
    *
    *        (C) 2003-2004 by Harald Welte <laforge@netfilter.org>
    *        Copyright �� CC Computer Consultants GmbH, 2007 - 2008
    *
    * 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>
  #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
  #include <linux/ipv6.h>
  #include <net/ipv6.h>
  #endif
  
  #include <net/net_namespace.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_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
  MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match");
  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;
  #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
                  struct {
                          __be32 src[4];
                          __be32 dst[4];
                  } ip6;
  #endif
          };
          __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;
          u_int8_t family;
  
          struct hashlimit_cfg1 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)
 {
         u_int32_t hash = jhash2((const u32 *)dst,
                                 sizeof(*dst)/sizeof(u32),
                                 ht->rnd);
         /*
          * Instead of returning hash % ht->cfg.size (implying a divide)
          * we return the high 32 bits of the (hash * ht->cfg.size) that will
          * give results between [0 and cfg.size-1] and same hash distribution,
          * but using a multiply, less expensive than a divide
          */
         return ((u64)hash * ht->cfg.size) >> 32;
 }
 
 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_v0(struct xt_hashlimit_info *minfo, u_int8_t 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 */
         hinfo->cfg.mode        = minfo->cfg.mode;
         hinfo->cfg.avg         = minfo->cfg.avg;
         hinfo->cfg.burst       = minfo->cfg.burst;
         hinfo->cfg.max         = minfo->cfg.max;
         hinfo->cfg.gc_interval = minfo->cfg.gc_interval;
         hinfo->cfg.expire      = minfo->cfg.expire;
 
         if (family == NFPROTO_IPV4)
                 hinfo->cfg.srcmask = hinfo->cfg.dstmask = 32;
         else
                 hinfo->cfg.srcmask = hinfo->cfg.dstmask = 128;
 
         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 = proc_create_data(minfo->name, 0,
                 (family == NFPROTO_IPV4) ?
                 hashlimit_procdir4 : hashlimit_procdir6,
                 &dl_file_ops, hinfo);
         if (!hinfo->pde) {
                 vfree(hinfo);
                 return -1;
         }
 
         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 int htable_create(struct xt_hashlimit_mtinfo1 *minfo, u_int8_t 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 == NULL) {
                 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 == 0)
                 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 = proc_create_data(minfo->name, 0,
                 (family == NFPROTO_IPV4) ?
                 hashlimit_procdir4 : hashlimit_procdir6,
                 &dl_file_ops, hinfo);
         if (hinfo->pde == NULL) {
                 vfree(hinfo);
                 return -1;
         }
 
         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 time_after_eq(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)
 {
         del_timer_sync(&hinfo->timer);
 
         /* remove proc entry */
         remove_proc_entry(hinfo->pde->name,
                           hinfo->family == NFPROTO_IPV4 ? hashlimit_procdir4 :
                                                      hashlimit_procdir6);
         htable_selective_cleanup(hinfo, select_all);
         vfree(hinfo);
 }
 
 static struct xt_hashlimit_htable *htable_find_get(const char *name,
                                                    u_int8_t 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 inline __be32 maskl(__be32 a, unsigned int l)
 {
         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 }
 
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 {
         switch (p) {
         case 0 ... 31:
                 i[0] = maskl(i[0], p);
                 i[1] = i[2] = i[3] = 0;
                 break;
         case 32 ... 63:
                 i[1] = maskl(i[1], p - 32);
                 i[2] = i[3] = 0;
                 break;
         case 64 ... 95:
                 i[2] = maskl(i[2], p - 64);
                 i[3] = 0;
         case 96 ... 127:
                 i[3] = maskl(i[3], p - 96);
                 break;
         case 128:
                 break;
         }
 }
 #endif
 
 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;
         u8 nexthdr;
 
         memset(dst, 0, sizeof(*dst));
 
         switch (hinfo->family) {
         case NFPROTO_IPV4:
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
                                       hinfo->cfg.dstmask);
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
                                       hinfo->cfg.srcmask);
 
                 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 NFPROTO_IPV6:
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
                                sizeof(dst->ip6.dst));
                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
                 }
                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
                                sizeof(dst->ip6.src));
                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
                 }
 
                 if (!(hinfo->cfg.mode &
                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
                         return 0;
                 nexthdr = ipv6_hdr(skb)->nexthdr;
                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
                 if ((int)protoff < 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_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
 {
         const struct xt_hashlimit_info *r =
                 ((const struct xt_hashlimit_info *)par->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, par->thoff) < 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:
         *par->hotdrop = true;
         return false;
 }
 
 static bool
 hashlimit_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 {
         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
         struct xt_hashlimit_htable *hinfo = info->hinfo;
         unsigned long now = jiffies;
         struct dsthash_ent *dh;
         struct dsthash_dst dst;
 
         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
                 goto hotdrop;
 
         spin_lock_bh(&hinfo->lock);
         dh = dsthash_find(hinfo, &dst);
         if (dh == NULL) {
                 dh = dsthash_alloc_init(hinfo, &dst);
                 if (dh == NULL) {
                         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) {
                 /* below the limit */
                 dh->rateinfo.credit -= dh->rateinfo.cost;
                 spin_unlock_bh(&hinfo->lock);
                 return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
         }
 
         spin_unlock_bh(&hinfo->lock);
         /* default match is underlimit - so over the limit, we need to invert */
         return info->cfg.mode & XT_HASHLIMIT_INVERT;
 
  hotdrop:
         *par->hotdrop = true;
         return false;
 }
 
 static bool hashlimit_mt_check_v0(const struct xt_mtchk_param *par)
 {
         struct xt_hashlimit_info *r = par->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, par->match->family);
         if (!r->hinfo && htable_create_v0(r, par->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 bool hashlimit_mt_check(const struct xt_mtchk_param *par)
 {
         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 
         /* Check for overflow. */
         if (info->cfg.burst == 0 ||
             user2credits(info->cfg.avg * info->cfg.burst) <
             user2credits(info->cfg.avg)) {
                 printk(KERN_ERR "xt_hashlimit: overflow, try lower: %u/%u\n",
                        info->cfg.avg, info->cfg.burst);
                 return false;
         }
         if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
                 return false;
         if (info->name[sizeof(info->name)-1] != '\0')
                 return false;
         if (par->match->family == NFPROTO_IPV4) {
                 if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
                         return false;
         } else {
                 if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
                         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);
         info->hinfo = htable_find_get(info->name, par->match->family);
         if (!info->hinfo && htable_create(info, par->match->family) != 0) {
                 mutex_unlock(&hlimit_mutex);
                 return false;
         }
         mutex_unlock(&hlimit_mutex);
         return true;
 }
 
 static void
 hashlimit_mt_destroy_v0(const struct xt_mtdtor_param *par)
 {
         const struct xt_hashlimit_info *r = par->matchinfo;
 
         htable_put(r->hinfo);
 }
 
 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
 {
         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
 
         htable_put(info->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 hashlimit_mt_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 hashlimit_mt_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 hashlimit_mt_reg[] __read_mostly = {
         {
                 .name                = "hashlimit",
                 .revision        = 0,
                 .family                = NFPROTO_IPV4,
                 .match                = hashlimit_mt_v0,
                 .matchsize        = sizeof(struct xt_hashlimit_info),
 #ifdef CONFIG_COMPAT
                 .compatsize        = sizeof(struct compat_xt_hashlimit_info),
                 .compat_from_user = hashlimit_mt_compat_from_user,
                 .compat_to_user        = hashlimit_mt_compat_to_user,
 #endif
                 .checkentry        = hashlimit_mt_check_v0,
                 .destroy        = hashlimit_mt_destroy_v0,
                 .me                = THIS_MODULE
         },
         {
                 .name           = "hashlimit",
                 .revision       = 1,
                 .family         = NFPROTO_IPV4,
                 .match          = hashlimit_mt,
                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
                 .checkentry     = hashlimit_mt_check,
                 .destroy        = hashlimit_mt_destroy,
                 .me             = THIS_MODULE,
         },
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
         {
                 .name                = "hashlimit",
                 .family                = NFPROTO_IPV6,
                 .match                = hashlimit_mt_v0,
                 .matchsize        = sizeof(struct xt_hashlimit_info),
 #ifdef CONFIG_COMPAT
                 .compatsize        = sizeof(struct compat_xt_hashlimit_info),
                 .compat_from_user = hashlimit_mt_compat_from_user,
                 .compat_to_user        = hashlimit_mt_compat_to_user,
 #endif
                 .checkentry        = hashlimit_mt_check_v0,
                 .destroy        = hashlimit_mt_destroy_v0,
                 .me                = THIS_MODULE
         },
         {
                 .name           = "hashlimit",
                 .revision       = 1,
                 .family         = NFPROTO_IPV6,
                 .match          = hashlimit_mt,
                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
                 .checkentry     = hashlimit_mt_check,
                 .destroy        = hashlimit_mt_destroy,
                 .me             = THIS_MODULE,
         },
 #endif
 };
 
 /* PROC stuff */
 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
         __acquires(htable->lock)
 {
         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)
         __releases(htable->lock)
 {
         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, u_int8_t family,
                                    struct seq_file *s)
 {
         /* recalculate to show accurate numbers */
         rateinfo_recalc(ent, jiffies);
 
         switch (family) {
         case NFPROTO_IPV4:
                 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.ip.src),
                                  ntohs(ent->dst.src_port),
                                  NIPQUAD(ent->dst.ip.dst),
                                  ntohs(ent->dst.dst_port),
                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
                                  ent->rateinfo.cost);
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
         case NFPROTO_IPV6:
                 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.ip6.src),
                                  ntohs(ent->dst.src_port),
                                  NIP6(*(struct in6_addr *)&ent->dst.ip6.dst),
                                  ntohs(ent->dst.dst_port),
                                  ent->rateinfo.credit, ent->rateinfo.credit_cap,
                                  ent->rateinfo.cost);
 #endif
         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 hashlimit_mt_init(void)
 {
         int err;
 
         err = xt_register_matches(hashlimit_mt_reg,
               ARRAY_SIZE(hashlimit_mt_reg));
         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", init_net.proc_net);
         if (!hashlimit_procdir4) {
                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
                                 "entry\n");
                 goto err3;
         }
         err = 0;
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
         hashlimit_procdir6 = proc_mkdir("ip6t_hashlimit", init_net.proc_net);
         if (!hashlimit_procdir6) {
                 printk(KERN_ERR "xt_hashlimit: unable to create proc dir "
                                 "entry\n");
                 err = -ENOMEM;
         }
 #endif
         if (!err)
                 return 0;
         remove_proc_entry("ipt_hashlimit", init_net.proc_net);
err3:
        kmem_cache_destroy(hashlimit_cachep);
err2:
        xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
err1:
        return err;

}

static void __exit hashlimit_mt_exit(void)
{
        remove_proc_entry("ipt_hashlimit", init_net.proc_net);
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
        remove_proc_entry("ip6t_hashlimit", init_net.proc_net);
#endif
        kmem_cache_destroy(hashlimit_cachep);
        xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
}

module_init(hashlimit_mt_init);
module_exit(hashlimit_mt_exit);