net/netfilter/xt_RATEEST.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * (C) 2007 Patrick McHardy <kaber@trash.net>
   4  */
   5 #include <linux/module.h>
   6 #include <linux/skbuff.h>
   7 #include <linux/gen_stats.h>
   8 #include <linux/jhash.h>
   9 #include <linux/rtnetlink.h>
  10 #include <linux/random.h>
  11 #include <linux/slab.h>
  12 #include <net/gen_stats.h>
  13 #include <net/netlink.h>
  14 #include <net/netns/generic.h>
  15
  16 #include <linux/netfilter/x_tables.h>
  17 #include <linux/netfilter/xt_RATEEST.h>
  18 #include <net/netfilter/xt_rateest.h>
  19
  20 #define RATEEST_HSIZE   16
  21
  22 struct xt_rateest_net {
  23         struct mutex hash_lock;
  24         struct hlist_head hash[RATEEST_HSIZE];
  25 };
  26
  27 static unsigned int xt_rateest_id;
  28
  29 static unsigned int jhash_rnd __read_mostly;
  30
  31 static unsigned int xt_rateest_hash(const char *name)
  32 {
  33         return jhash(name, sizeof_field(struct xt_rateest, name), jhash_rnd) &
  34                (RATEEST_HSIZE - 1);
  35 }
  36
  37 static void xt_rateest_hash_insert(struct xt_rateest_net *xn,
  38                                    struct xt_rateest *est)
  39 {
  40         unsigned int h;
  41
  42         h = xt_rateest_hash(est->name);
  43         hlist_add_head(&est->list, &xn->hash[h]);
  44 }
  45
  46 static struct xt_rateest *__xt_rateest_lookup(struct xt_rateest_net *xn,
  47                                               const char *name)
  48 {
  49         struct xt_rateest *est;
  50         unsigned int h;
  51
  52         h = xt_rateest_hash(name);
  53         hlist_for_each_entry(est, &xn->hash[h], list) {
  54                 if (strcmp(est->name, name) == 0) {
  55                         est->refcnt++;
  56                         return est;
  57                 }
  58         }
  59
  60         return NULL;
  61 }
  62
  63 struct xt_rateest *xt_rateest_lookup(struct net *net, const char *name)
  64 {
  65         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
  66         struct xt_rateest *est;
  67
  68         mutex_lock(&xn->hash_lock);
  69         est = __xt_rateest_lookup(xn, name);
  70         mutex_unlock(&xn->hash_lock);
  71         return est;
  72 }
  73 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
  74
  75 void xt_rateest_put(struct net *net, struct xt_rateest *est)
  76 {
  77         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
  78
  79         mutex_lock(&xn->hash_lock);
  80         if (--est->refcnt == 0) {
  81                 hlist_del(&est->list);
  82                 gen_kill_estimator(&est->rate_est);
  83                 /*
  84                  * gen_estimator est_timer() might access est->lock or bstats,
  85                  * wait a RCU grace period before freeing 'est'
  86                  */
  87                 kfree_rcu(est, rcu);
  88         }
  89         mutex_unlock(&xn->hash_lock);
  90 }
  91 EXPORT_SYMBOL_GPL(xt_rateest_put);
  92
  93 static unsigned int
  94 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
  95 {
  96         const struct xt_rateest_target_info *info = par->targinfo;
  97         struct gnet_stats_basic_sync *stats = &info->est->bstats;
  98
  99         spin_lock_bh(&info->est->lock);
 100         u64_stats_add(&stats->bytes, skb->len);
 101         u64_stats_inc(&stats->packets);
 102         spin_unlock_bh(&info->est->lock);
 103
 104         return XT_CONTINUE;
 105 }
 106
 107 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 108 {
 109         struct xt_rateest_net *xn = net_generic(par->net, xt_rateest_id);
 110         struct xt_rateest_target_info *info = par->targinfo;
 111         struct xt_rateest *est;
 112         struct {
 113                 struct nlattr           opt;
 114                 struct gnet_estimator   est;
 115         } cfg;
 116         int ret;
 117
 118         if (strnlen(info->name, sizeof(est->name)) >= sizeof(est->name))
 119                 return -ENAMETOOLONG;
 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         gnet_stats_basic_sync_init(&est->bstats);
 147         strlcpy(est->name, info->name, sizeof(est->name));
 148         spin_lock_init(&est->lock);
 149         est->refcnt             = 1;
 150         est->params.interval    = info->interval;
 151         est->params.ewma_log    = info->ewma_log;
 152
 153         cfg.opt.nla_len         = nla_attr_size(sizeof(cfg.est));
 154         cfg.opt.nla_type        = TCA_STATS_RATE_EST;
 155         cfg.est.interval        = info->interval;
 156         cfg.est.ewma_log        = info->ewma_log;
 157
 158         ret = gen_new_estimator(&est->bstats, NULL, &est->rate_est,
 159                                 &est->lock, NULL, &cfg.opt);
 160         if (ret < 0)
 161                 goto err2;
 162
 163         info->est = est;
 164         xt_rateest_hash_insert(xn, est);
 165         mutex_unlock(&xn->hash_lock);
 166         return 0;
 167
 168 err2:
 169         kfree(est);
 170 err1:
 171         mutex_unlock(&xn->hash_lock);
 172         return ret;
 173 }
 174
 175 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
 176 {
 177         struct xt_rateest_target_info *info = par->targinfo;
 178
 179         xt_rateest_put(par->net, info->est);
 180 }
 181
 182 static struct xt_target xt_rateest_tg_reg __read_mostly = {
 183         .name       = "RATEEST",
 184         .revision   = 0,
 185         .family     = NFPROTO_UNSPEC,
 186         .target     = xt_rateest_tg,
 187         .checkentry = xt_rateest_tg_checkentry,
 188         .destroy    = xt_rateest_tg_destroy,
 189         .targetsize = sizeof(struct xt_rateest_target_info),
 190         .usersize   = offsetof(struct xt_rateest_target_info, est),
 191         .me         = THIS_MODULE,
 192 };
 193
 194 static __net_init int xt_rateest_net_init(struct net *net)
 195 {
 196         struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
 197         int i;
 198
 199         mutex_init(&xn->hash_lock);
 200         for (i = 0; i < ARRAY_SIZE(xn->hash); i++)
 201                 INIT_HLIST_HEAD(&xn->hash[i]);
 202         return 0;
 203 }
 204
 205 static struct pernet_operations xt_rateest_net_ops = {
 206         .init = xt_rateest_net_init,
 207         .id   = &xt_rateest_id,
 208         .size = sizeof(struct xt_rateest_net),
 209 };
 210
 211 static int __init xt_rateest_tg_init(void)
 212 {
 213         int err = register_pernet_subsys(&xt_rateest_net_ops);
 214
 215         if (err)
 216                 return err;
 217         return xt_register_target(&xt_rateest_tg_reg);
 218 }
 219
 220 static void __exit xt_rateest_tg_fini(void)
 221 {
 222         xt_unregister_target(&xt_rateest_tg_reg);
 223         unregister_pernet_subsys(&xt_rateest_net_ops);
 224 }
 225
 226
 227 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 228 MODULE_LICENSE("GPL");
 229 MODULE_DESCRIPTION("Xtables: packet rate estimator");
 230 MODULE_ALIAS("ipt_RATEEST");
 231 MODULE_ALIAS("ip6t_RATEEST");
 232 module_init(xt_rateest_tg_init);
 233 module_exit(xt_rateest_tg_fini);