net/netfilter/xt_RATEEST.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * (C) 2007 Patrick McHardy <kaber@trash.net>
0004  */
0005 #include <linux/module.h>
0006 #include <linux/skbuff.h>
0007 #include <linux/gen_stats.h>
0008 #include <linux/jhash.h>
0009 #include <linux/rtnetlink.h>
0010 #include <linux/random.h>
0011 #include <linux/slab.h>
0012 #include <net/gen_stats.h>
0013 #include <net/netlink.h>
0014 #include <net/netns/generic.h>
0015
0016 #include <linux/netfilter/x_tables.h>
0017 #include <linux/netfilter/xt_RATEEST.h>
0018 #include <net/netfilter/xt_rateest.h>
0019
0020 #define RATEEST_HSIZE   16
0021
0022 struct xt_rateest_net {
0023     struct mutex hash_lock;
0024     struct hlist_head hash[RATEEST_HSIZE];
0025 };
0026
0027 static unsigned int xt_rateest_id;
0028
0029 static unsigned int jhash_rnd __read_mostly;
0030
0031 static unsigned int xt_rateest_hash(const char *name)
0032 {
0033     return jhash(name, sizeof_field(struct xt_rateest, name), jhash_rnd) &
0034            (RATEEST_HSIZE - 1);
0035 }
0036
0037 static void xt_rateest_hash_insert(struct xt_rateest_net *xn,
0038                    struct xt_rateest *est)
0039 {
0040     unsigned int h;
0041
0042     h = xt_rateest_hash(est->name);
0043     hlist_add_head(&est->list, &xn->hash[h]);
0044 }
0045
0046 static struct xt_rateest *__xt_rateest_lookup(struct xt_rateest_net *xn,
0047                           const char *name)
0048 {
0049     struct xt_rateest *est;
0050     unsigned int h;
0051
0052     h = xt_rateest_hash(name);
0053     hlist_for_each_entry(est, &xn->hash[h], list) {
0054         if (strcmp(est->name, name) == 0) {
0055             est->refcnt++;
0056             return est;
0057         }
0058     }
0059
0060     return NULL;
0061 }
0062
0063 struct xt_rateest *xt_rateest_lookup(struct net *net, const char *name)
0064 {
0065     struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
0066     struct xt_rateest *est;
0067
0068     mutex_lock(&xn->hash_lock);
0069     est = __xt_rateest_lookup(xn, name);
0070     mutex_unlock(&xn->hash_lock);
0071     return est;
0072 }
0073 EXPORT_SYMBOL_GPL(xt_rateest_lookup);
0074
0075 void xt_rateest_put(struct net *net, struct xt_rateest *est)
0076 {
0077     struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
0078
0079     mutex_lock(&xn->hash_lock);
0080     if (--est->refcnt == 0) {
0081         hlist_del(&est->list);
0082         gen_kill_estimator(&est->rate_est);
0083         /*
0084          * gen_estimator est_timer() might access est->lock or bstats,
0085          * wait a RCU grace period before freeing 'est'
0086          */
0087         kfree_rcu(est, rcu);
0088     }
0089     mutex_unlock(&xn->hash_lock);
0090 }
0091 EXPORT_SYMBOL_GPL(xt_rateest_put);
0092
0093 static unsigned int
0094 xt_rateest_tg(struct sk_buff *skb, const struct xt_action_param *par)
0095 {
0096     const struct xt_rateest_target_info *info = par->targinfo;
0097     struct gnet_stats_basic_sync *stats = &info->est->bstats;
0098
0099     spin_lock_bh(&info->est->lock);
0100     u64_stats_add(&stats->bytes, skb->len);
0101     u64_stats_inc(&stats->packets);
0102     spin_unlock_bh(&info->est->lock);
0103
0104     return XT_CONTINUE;
0105 }
0106
0107 static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
0108 {
0109     struct xt_rateest_net *xn = net_generic(par->net, xt_rateest_id);
0110     struct xt_rateest_target_info *info = par->targinfo;
0111     struct xt_rateest *est;
0112     struct {
0113         struct nlattr       opt;
0114         struct gnet_estimator   est;
0115     } cfg;
0116     int ret;
0117
0118     if (strnlen(info->name, sizeof(est->name)) >= sizeof(est->name))
0119         return -ENAMETOOLONG;
0120
0121     net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));
0122
0123     mutex_lock(&xn->hash_lock);
0124     est = __xt_rateest_lookup(xn, info->name);
0125     if (est) {
0126         mutex_unlock(&xn->hash_lock);
0127         /*
0128          * If estimator parameters are specified, they must match the
0129          * existing estimator.
0130          */
0131         if ((!info->interval && !info->ewma_log) ||
0132             (info->interval != est->params.interval ||
0133              info->ewma_log != est->params.ewma_log)) {
0134             xt_rateest_put(par->net, est);
0135             return -EINVAL;
0136         }
0137         info->est = est;
0138         return 0;
0139     }
0140
0141     ret = -ENOMEM;
0142     est = kzalloc(sizeof(*est), GFP_KERNEL);
0143     if (!est)
0144         goto err1;
0145
0146     gnet_stats_basic_sync_init(&est->bstats);
0147     strlcpy(est->name, info->name, sizeof(est->name));
0148     spin_lock_init(&est->lock);
0149     est->refcnt     = 1;
0150     est->params.interval    = info->interval;
0151     est->params.ewma_log    = info->ewma_log;
0152
0153     cfg.opt.nla_len     = nla_attr_size(sizeof(cfg.est));
0154     cfg.opt.nla_type    = TCA_STATS_RATE_EST;
0155     cfg.est.interval    = info->interval;
0156     cfg.est.ewma_log    = info->ewma_log;
0157
0158     ret = gen_new_estimator(&est->bstats, NULL, &est->rate_est,
0159                 &est->lock, NULL, &cfg.opt);
0160     if (ret < 0)
0161         goto err2;
0162
0163     info->est = est;
0164     xt_rateest_hash_insert(xn, est);
0165     mutex_unlock(&xn->hash_lock);
0166     return 0;
0167
0168 err2:
0169     kfree(est);
0170 err1:
0171     mutex_unlock(&xn->hash_lock);
0172     return ret;
0173 }
0174
0175 static void xt_rateest_tg_destroy(const struct xt_tgdtor_param *par)
0176 {
0177     struct xt_rateest_target_info *info = par->targinfo;
0178
0179     xt_rateest_put(par->net, info->est);
0180 }
0181
0182 static struct xt_target xt_rateest_tg_reg __read_mostly = {
0183     .name       = "RATEEST",
0184     .revision   = 0,
0185     .family     = NFPROTO_UNSPEC,
0186     .target     = xt_rateest_tg,
0187     .checkentry = xt_rateest_tg_checkentry,
0188     .destroy    = xt_rateest_tg_destroy,
0189     .targetsize = sizeof(struct xt_rateest_target_info),
0190     .usersize   = offsetof(struct xt_rateest_target_info, est),
0191     .me         = THIS_MODULE,
0192 };
0193
0194 static __net_init int xt_rateest_net_init(struct net *net)
0195 {
0196     struct xt_rateest_net *xn = net_generic(net, xt_rateest_id);
0197     int i;
0198
0199     mutex_init(&xn->hash_lock);
0200     for (i = 0; i < ARRAY_SIZE(xn->hash); i++)
0201         INIT_HLIST_HEAD(&xn->hash[i]);
0202     return 0;
0203 }
0204
0205 static struct pernet_operations xt_rateest_net_ops = {
0206     .init = xt_rateest_net_init,
0207     .id   = &xt_rateest_id,
0208     .size = sizeof(struct xt_rateest_net),
0209 };
0210
0211 static int __init xt_rateest_tg_init(void)
0212 {
0213     int err = register_pernet_subsys(&xt_rateest_net_ops);
0214
0215     if (err)
0216         return err;
0217     return xt_register_target(&xt_rateest_tg_reg);
0218 }
0219
0220 static void __exit xt_rateest_tg_fini(void)
0221 {
0222     xt_unregister_target(&xt_rateest_tg_reg);
0223     unregister_pernet_subsys(&xt_rateest_net_ops);
0224 }
0225
0226
0227 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
0228 MODULE_LICENSE("GPL");
0229 MODULE_DESCRIPTION("Xtables: packet rate estimator");
0230 MODULE_ALIAS("ipt_RATEEST");
0231 MODULE_ALIAS("ip6t_RATEEST");
0232 module_init(xt_rateest_tg_init);
0233 module_exit(xt_rateest_tg_fini);