linux/net/netfilter/nft_connlimit.c
<<
>>
Prefs
   1/* SPDX-License-Identifier: GPL-2.0 */
   2#include <linux/kernel.h>
   3#include <linux/init.h>
   4#include <linux/module.h>
   5#include <linux/spinlock.h>
   6#include <linux/netlink.h>
   7#include <linux/netfilter.h>
   8#include <linux/netfilter/nf_tables.h>
   9#include <net/netfilter/nf_tables.h>
  10#include <net/netfilter/nf_conntrack.h>
  11#include <net/netfilter/nf_conntrack_count.h>
  12#include <net/netfilter/nf_conntrack_core.h>
  13#include <net/netfilter/nf_conntrack_tuple.h>
  14#include <net/netfilter/nf_conntrack_zones.h>
  15
  16struct nft_connlimit {
  17        struct nf_conncount_list        list;
  18        u32                             limit;
  19        bool                            invert;
  20};
  21
  22static inline void nft_connlimit_do_eval(struct nft_connlimit *priv,
  23                                         struct nft_regs *regs,
  24                                         const struct nft_pktinfo *pkt,
  25                                         const struct nft_set_ext *ext)
  26{
  27        const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
  28        const struct nf_conntrack_tuple *tuple_ptr;
  29        struct nf_conntrack_tuple tuple;
  30        enum ip_conntrack_info ctinfo;
  31        const struct nf_conn *ct;
  32        unsigned int count;
  33
  34        tuple_ptr = &tuple;
  35
  36        ct = nf_ct_get(pkt->skb, &ctinfo);
  37        if (ct != NULL) {
  38                tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
  39                zone = nf_ct_zone(ct);
  40        } else if (!nf_ct_get_tuplepr(pkt->skb, skb_network_offset(pkt->skb),
  41                                      nft_pf(pkt), nft_net(pkt), &tuple)) {
  42                regs->verdict.code = NF_DROP;
  43                return;
  44        }
  45
  46        if (nf_conncount_add(nft_net(pkt), &priv->list, tuple_ptr, zone)) {
  47                regs->verdict.code = NF_DROP;
  48                return;
  49        }
  50
  51        count = priv->list.count;
  52
  53        if ((count > priv->limit) ^ priv->invert) {
  54                regs->verdict.code = NFT_BREAK;
  55                return;
  56        }
  57}
  58
  59static int nft_connlimit_do_init(const struct nft_ctx *ctx,
  60                                 const struct nlattr * const tb[],
  61                                 struct nft_connlimit *priv)
  62{
  63        bool invert = false;
  64        u32 flags, limit;
  65
  66        if (!tb[NFTA_CONNLIMIT_COUNT])
  67                return -EINVAL;
  68
  69        limit = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_COUNT]));
  70
  71        if (tb[NFTA_CONNLIMIT_FLAGS]) {
  72                flags = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_FLAGS]));
  73                if (flags & ~NFT_CONNLIMIT_F_INV)
  74                        return -EOPNOTSUPP;
  75                if (flags & NFT_CONNLIMIT_F_INV)
  76                        invert = true;
  77        }
  78
  79        nf_conncount_list_init(&priv->list);
  80        priv->limit     = limit;
  81        priv->invert    = invert;
  82
  83        return nf_ct_netns_get(ctx->net, ctx->family);
  84}
  85
  86static void nft_connlimit_do_destroy(const struct nft_ctx *ctx,
  87                                     struct nft_connlimit *priv)
  88{
  89        nf_ct_netns_put(ctx->net, ctx->family);
  90        nf_conncount_cache_free(&priv->list);
  91}
  92
  93static int nft_connlimit_do_dump(struct sk_buff *skb,
  94                                 struct nft_connlimit *priv)
  95{
  96        if (nla_put_be32(skb, NFTA_CONNLIMIT_COUNT, htonl(priv->limit)))
  97                goto nla_put_failure;
  98        if (priv->invert &&
  99            nla_put_be32(skb, NFTA_CONNLIMIT_FLAGS, htonl(NFT_CONNLIMIT_F_INV)))
 100                goto nla_put_failure;
 101
 102        return 0;
 103
 104nla_put_failure:
 105        return -1;
 106}
 107
 108static inline void nft_connlimit_obj_eval(struct nft_object *obj,
 109                                        struct nft_regs *regs,
 110                                        const struct nft_pktinfo *pkt)
 111{
 112        struct nft_connlimit *priv = nft_obj_data(obj);
 113
 114        nft_connlimit_do_eval(priv, regs, pkt, NULL);
 115}
 116
 117static int nft_connlimit_obj_init(const struct nft_ctx *ctx,
 118                                const struct nlattr * const tb[],
 119                                struct nft_object *obj)
 120{
 121        struct nft_connlimit *priv = nft_obj_data(obj);
 122
 123        return nft_connlimit_do_init(ctx, tb, priv);
 124}
 125
 126static void nft_connlimit_obj_destroy(const struct nft_ctx *ctx,
 127                                      struct nft_object *obj)
 128{
 129        struct nft_connlimit *priv = nft_obj_data(obj);
 130
 131        nft_connlimit_do_destroy(ctx, priv);
 132}
 133
 134static int nft_connlimit_obj_dump(struct sk_buff *skb,
 135                                  struct nft_object *obj, bool reset)
 136{
 137        struct nft_connlimit *priv = nft_obj_data(obj);
 138
 139        return nft_connlimit_do_dump(skb, priv);
 140}
 141
 142static const struct nla_policy nft_connlimit_policy[NFTA_CONNLIMIT_MAX + 1] = {
 143        [NFTA_CONNLIMIT_COUNT]  = { .type = NLA_U32 },
 144        [NFTA_CONNLIMIT_FLAGS]  = { .type = NLA_U32 },
 145};
 146
 147static struct nft_object_type nft_connlimit_obj_type;
 148static const struct nft_object_ops nft_connlimit_obj_ops = {
 149        .type           = &nft_connlimit_obj_type,
 150        .size           = sizeof(struct nft_connlimit),
 151        .eval           = nft_connlimit_obj_eval,
 152        .init           = nft_connlimit_obj_init,
 153        .destroy        = nft_connlimit_obj_destroy,
 154        .dump           = nft_connlimit_obj_dump,
 155};
 156
 157static struct nft_object_type nft_connlimit_obj_type __read_mostly = {
 158        .type           = NFT_OBJECT_CONNLIMIT,
 159        .ops            = &nft_connlimit_obj_ops,
 160        .maxattr        = NFTA_CONNLIMIT_MAX,
 161        .policy         = nft_connlimit_policy,
 162        .owner          = THIS_MODULE,
 163};
 164
 165static void nft_connlimit_eval(const struct nft_expr *expr,
 166                               struct nft_regs *regs,
 167                               const struct nft_pktinfo *pkt)
 168{
 169        struct nft_connlimit *priv = nft_expr_priv(expr);
 170
 171        nft_connlimit_do_eval(priv, regs, pkt, NULL);
 172}
 173
 174static int nft_connlimit_dump(struct sk_buff *skb, const struct nft_expr *expr)
 175{
 176        struct nft_connlimit *priv = nft_expr_priv(expr);
 177
 178        return nft_connlimit_do_dump(skb, priv);
 179}
 180
 181static int nft_connlimit_init(const struct nft_ctx *ctx,
 182                              const struct nft_expr *expr,
 183                              const struct nlattr * const tb[])
 184{
 185        struct nft_connlimit *priv = nft_expr_priv(expr);
 186
 187        return nft_connlimit_do_init(ctx, tb, priv);
 188}
 189
 190static void nft_connlimit_destroy(const struct nft_ctx *ctx,
 191                                const struct nft_expr *expr)
 192{
 193        struct nft_connlimit *priv = nft_expr_priv(expr);
 194
 195        nft_connlimit_do_destroy(ctx, priv);
 196}
 197
 198static int nft_connlimit_clone(struct nft_expr *dst, const struct nft_expr *src)
 199{
 200        struct nft_connlimit *priv_dst = nft_expr_priv(dst);
 201        struct nft_connlimit *priv_src = nft_expr_priv(src);
 202
 203        nf_conncount_list_init(&priv_dst->list);
 204        priv_dst->limit  = priv_src->limit;
 205        priv_dst->invert = priv_src->invert;
 206
 207        return 0;
 208}
 209
 210static void nft_connlimit_destroy_clone(const struct nft_ctx *ctx,
 211                                        const struct nft_expr *expr)
 212{
 213        struct nft_connlimit *priv = nft_expr_priv(expr);
 214
 215        nf_conncount_cache_free(&priv->list);
 216}
 217
 218static bool nft_connlimit_gc(struct net *net, const struct nft_expr *expr)
 219{
 220        struct nft_connlimit *priv = nft_expr_priv(expr);
 221        bool ret;
 222
 223        local_bh_disable();
 224        ret = nf_conncount_gc_list(net, &priv->list);
 225        local_bh_enable();
 226
 227        return ret;
 228}
 229
 230static struct nft_expr_type nft_connlimit_type;
 231static const struct nft_expr_ops nft_connlimit_ops = {
 232        .type           = &nft_connlimit_type,
 233        .size           = NFT_EXPR_SIZE(sizeof(struct nft_connlimit)),
 234        .eval           = nft_connlimit_eval,
 235        .init           = nft_connlimit_init,
 236        .destroy        = nft_connlimit_destroy,
 237        .clone          = nft_connlimit_clone,
 238        .destroy_clone  = nft_connlimit_destroy_clone,
 239        .dump           = nft_connlimit_dump,
 240        .gc             = nft_connlimit_gc,
 241};
 242
 243static struct nft_expr_type nft_connlimit_type __read_mostly = {
 244        .name           = "connlimit",
 245        .ops            = &nft_connlimit_ops,
 246        .policy         = nft_connlimit_policy,
 247        .maxattr        = NFTA_CONNLIMIT_MAX,
 248        .flags          = NFT_EXPR_STATEFUL | NFT_EXPR_GC,
 249        .owner          = THIS_MODULE,
 250};
 251
 252static int __init nft_connlimit_module_init(void)
 253{
 254        int err;
 255
 256        err = nft_register_obj(&nft_connlimit_obj_type);
 257        if (err < 0)
 258                return err;
 259
 260        err = nft_register_expr(&nft_connlimit_type);
 261        if (err < 0)
 262                goto err1;
 263
 264        return 0;
 265err1:
 266        nft_unregister_obj(&nft_connlimit_obj_type);
 267        return err;
 268}
 269
 270static void __exit nft_connlimit_module_exit(void)
 271{
 272        nft_unregister_expr(&nft_connlimit_type);
 273        nft_unregister_obj(&nft_connlimit_obj_type);
 274}
 275
 276module_init(nft_connlimit_module_init);
 277module_exit(nft_connlimit_module_exit);
 278
 279MODULE_LICENSE("GPL");
 280MODULE_AUTHOR("Pablo Neira Ayuso");
 281MODULE_ALIAS_NFT_EXPR("connlimit");
 282MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT);
 283MODULE_DESCRIPTION("nftables connlimit rule support");
 284