net/netfilter/nft_connlimit.c

   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
  16 struct nft_connlimit {
  17         struct nf_conncount_list        list;
  18         u32                             limit;
  19         bool                            invert;
  20 };
  21
  22 static 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
  59 static 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
  86 static 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
  93 static 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
 104 nla_put_failure:
 105         return -1;
 106 }
 107
 108 static 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
 117 static 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
 126 static 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
 134 static 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
 142 static 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
 147 static struct nft_object_type nft_connlimit_obj_type;
 148 static 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
 157 static 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
 165 static 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
 174 static 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
 181 static 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
 190 static 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
 198 static 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
 210 static 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
 218 static 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
 230 static struct nft_expr_type nft_connlimit_type;
 231 static 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
 243 static 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
 252 static 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;
 265 err1:
 266         nft_unregister_obj(&nft_connlimit_obj_type);
 267         return err;
 268 }
 269
 270 static 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
 276 module_init(nft_connlimit_module_init);
 277 module_exit(nft_connlimit_module_exit);
 278
 279 MODULE_LICENSE("GPL");
 280 MODULE_AUTHOR("Pablo Neira Ayuso");
 281 MODULE_ALIAS_NFT_EXPR("connlimit");
 282 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT);
 283 MODULE_DESCRIPTION("nftables connlimit rule support");