net/netfilter/xt_RATEEST.c

   1 /*
   2  * (C) 2007 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8 #include <linux/module.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/gen_stats.h>
  11 #include <linux/jhash.h>
  12 #include <linux/rtnetlink.h>
  13 #include <linux/random.h>
  14 #include <linux/slab.h>
  15 #include <net/gen_stats.h>
  16 #include <net/netlink.h>
  17 #include <net/netns/generic.h>
  18
  19 #include <linux/netfilter/x_tables.h>
  20 #include <linux/netfilter/xt_RATEEST.h>
  21 #include <net/netfilter/xt_rateest.h>
  22
  23 #define RATEEST_HSIZE   16
  24
  25 struct xt_rateest_net {
  26         struct mutex hash_lock;
  27         struct hlist_head hash[RATEEST_HSIZE];
  28 };
  29
  30 static unsigned int xt_rateest_id;
  31
  32 static unsigned int jhash_rnd __read_mostly;
  33
  34 static unsigned int xt_rateest_hash(const char *name)
  35 {
  36         return jhash(name, FIELD_SIZEOF(struct xt_rateest, name), jhash_rnd) &
  37                (RATEEST_HSIZE - 1);
  38 }
  39
  40 static void xt_rateest_hash_insert(struct xt_rateest_net *xn,
  41                                    struct xt_rateest *est)
  42 {
  43         unsigned int h;
  44
  45         h = xt_rateest_hash(est->name);
  46         hlist_add_head(&est->list, &xn->hash[h]);
  47 }
  48
  49 static struct xt_rateest *__xt_rateest_lookup(struct xt_rateest_net *xn,
  50                                               const char *name)
  51 {
  52         struct xt_rateest *est;
  53         unsigned int h;
  54
  55         h = xt_rateest_hash(name);
  56         hlist_for_each_entry(est, &xn->hash[h], list) {
  57                 if (strcmp(est->name, name) == 0) {
  58                         est->refcnt++;
  59                         return est;
  60                 }
  61         }
  62
  63         return NULL;
  64 }
  65
  66 struct xt_rateest *xt_rateest_lookup(struct net *net, const char *name)
  67 {
  68         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
  69         struct xt_rateest *est;
  70
  71         mutex_lock(&xn->hash_lock);
  72         est = __xt_rateest_lookup(xn, name);
  73         mutex_unlock(&xn->hash_lock);
  74         return est;
  75 }
  76 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  77
  78 void xt_rateest_put(struct net *net, struct xt_rateest *est)
  79 {
  80         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
  81
  82         mutex_lock(&xn->hash_lock);
  83         if (--est->refcnt == 0) {
  84                 hlist_del(&est->list);
  85                 gen_kill_estimator(&est->rate_est);
  86                 /*
  87                  * gen_estimator est_timer() might access est->lock or bstats,
  88                  * wait a RCU grace period before freeing 'est'
  89                  */
  90                 kfree_rcu(est, rcu);
  91         }
  92         mutex_unlock(&xn->hash_lock);
  93 }
  94 EXPORT_SYMBOL_GPL(xt_rateest_put);
  95
  96 static unsigned int
  97 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
  98 {
  99         const struct xt_rateest_target_info *info = par->targinfo;
 100         struct gnet_stats_basic_packed *stats = &info->est->bstats;
 101
 102         spin_lock_bh(&info->est->lock);
 103         stats->bytes += skb->len;
 104         stats->packets++;
 105         spin_unlock_bh(&info->est->lock);
 106
 107         return XT_CONTINUE;
 108 }
 109
 110 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 111 {
 112         struct xt_rateest_net *xn = net_generic(par->net, xt_rateest_id);
 113         struct xt_rateest_target_info *info = par->targinfo;
 114         struct xt_rateest *est;
 115         struct {
 116                 struct nlattr           opt;
 117                 struct gnet_estimator   est;
 118         } cfg;
 119         int ret;
 120
 121         net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
 122
 123         mutex_lock(&xn->hash_lock);
 124         est = __xt_rateest_lookup(xn, info->name);
 125         if (est) {
 126                 mutex_unlock(&xn->hash_lock);
 127                 /*
 128                  * If estimator parameters are specified, they must match the
 129                  * existing estimator.
 130                  */
 131                 if ((!info->interval && !info->ewma_log) ||
 132                     (info->interval != est->params.interval ||
 133                      info->ewma_log != est->params.ewma_log)) {
 134                         xt_rateest_put(par->net, est);
 135                         return -EINVAL;
 136                 }
 137                 info->est = est;
 138                 return 0;
 139         }
 140
 141         ret = -ENOMEM;
 142         est = kzalloc(sizeof(*est), GFP_KERNEL);
 143         if (!est)
 144                 goto err1;
 145
 146         strlcpy(est->name, info->name, sizeof(est->name));
 147         spin_lock_init(&est->lock);
 148         est->refcnt             = 1;
 149         est->params.interval    = info->interval;
 150         est->params.ewma_log    = info->ewma_log;
 151
 152         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 153         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 154         cfg.est.interval        = info->interval;
 155         cfg.est.ewma_log        = info->ewma_log;
 156
 157         ret = gen_new_estimator(&est->bstats, NULL, &est->rate_est,
 158                                 &est->lock, NULL, &cfg.opt);
 159         if (ret < 0)
 160                 goto err2;
 161
 162         info->est = est;
 163         xt_rateest_hash_insert(xn, est);
 164         mutex_unlock(&xn->hash_lock);
 165         return 0;
 166
 167 err2:
 168         kfree(est);
 169 err1:
 170         mutex_unlock(&xn->hash_lock);
 171         return ret;
 172 }
 173
 174 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 175 {
 176         struct xt_rateest_target_info *info = par->targinfo;
 177
 178         xt_rateest_put(par->net, info->est);
 179 }
 180
 181 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 182         .name       = "RATEEST",
 183         .revision   = 0,
 184         .family     = NFPROTO_UNSPEC,
 185         .target     = xt_rateest_tg,
 186         .checkentry = xt_rateest_tg_checkentry,
 187         .destroy    = xt_rateest_tg_destroy,
 188         .targetsize = sizeof(struct xt_rateest_target_info),
 189         .usersize   = offsetof(struct xt_rateest_target_info, est),
 190         .me         = THIS_MODULE,
 191 };
 192
 193 static __net_init int xt_rateest_net_init(struct net *net)
 194 {
 195         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
 196         int i;
 197
 198         mutex_init(&xn->hash_lock);
 199         for (i = 0; i < ARRAY_SIZE(xn->hash); i++)
 200                 INIT_HLIST_HEAD(&xn->hash[i]);
 201         return 0;
 202 }
 203
 204 static struct pernet_operations xt_rateest_net_ops = {
 205         .init = xt_rateest_net_init,
 206         .id   = &xt_rateest_id,
 207         .size = sizeof(struct xt_rateest_net),
 208 };
 209
 210 static int __init xt_rateest_tg_init(void)
 211 {
 212         int err = register_pernet_subsys(&xt_rateest_net_ops);
 213
 214         if (err)
 215                 return err;
 216         return xt_register_target(&xt_rateest_tg_reg);
 217 }
 218
 219 static void __exit xt_rateest_tg_fini(void)
 220 {
 221         xt_unregister_target(&xt_rateest_tg_reg);
 222         unregister_pernet_subsys(&xt_rateest_net_ops);
 223 }
 224
 225
 226 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 227 MODULE_LICENSE("GPL");
 228 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 229 MODULE_ALIAS("ipt_RATEEST");
 230 MODULE_ALIAS("ip6t_RATEEST");
 231 module_init(xt_rateest_tg_init);
 232 module_exit(xt_rateest_tg_fini);