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 int err; 66 67 if (!tb[NFTA_CONNLIMIT_COUNT]) 68 return -EINVAL; 69 70 limit = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_COUNT])); 71 72 if (tb[NFTA_CONNLIMIT_FLAGS]) { 73 flags = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_FLAGS])); 74 if (flags & ~NFT_CONNLIMIT_F_INV) 75 return -EOPNOTSUPP; 76 if (flags & NFT_CONNLIMIT_F_INV) 77 invert = true; 78 } 79 80 priv->list = kmalloc(sizeof(*priv->list), GFP_KERNEL_ACCOUNT); 81 if (!priv->list) 82 return -ENOMEM; 83 84 nf_conncount_list_init(priv->list); 85 priv->limit = limit; 86 priv->invert = invert; 87 88 err = nf_ct_netns_get(ctx->net, ctx->family); 89 if (err < 0) 90 goto err_netns; 91 92 return 0; 93 err_netns: 94 kfree(priv->list); 95 96 return err; 97 } 98 99 static void nft_connlimit_do_destroy(const struct nft_ctx *ctx, 100 struct nft_connlimit *priv) 101 { 102 nf_ct_netns_put(ctx->net, ctx->family); 103 nf_conncount_cache_free(priv->list); 104 kfree(priv->list); 105 } 106 107 static int nft_connlimit_do_dump(struct sk_buff *skb, 108 struct nft_connlimit *priv) 109 { 110 if (nla_put_be32(skb, NFTA_CONNLIMIT_COUNT, htonl(priv->limit))) 111 goto nla_put_failure; 112 if (priv->invert && 113 nla_put_be32(skb, NFTA_CONNLIMIT_FLAGS, htonl(NFT_CONNLIMIT_F_INV))) 114 goto nla_put_failure; 115 116 return 0; 117 118 nla_put_failure: 119 return -1; 120 } 121 122 static inline void nft_connlimit_obj_eval(struct nft_object *obj, 123 struct nft_regs *regs, 124 const struct nft_pktinfo *pkt) 125 { 126 struct nft_connlimit *priv = nft_obj_data(obj); 127 128 nft_connlimit_do_eval(priv, regs, pkt, NULL); 129 } 130 131 static int nft_connlimit_obj_init(const struct nft_ctx *ctx, 132 const struct nlattr * const tb[], 133 struct nft_object *obj) 134 { 135 struct nft_connlimit *priv = nft_obj_data(obj); 136 137 return nft_connlimit_do_init(ctx, tb, priv); 138 } 139 140 static void nft_connlimit_obj_destroy(const struct nft_ctx *ctx, 141 struct nft_object *obj) 142 { 143 struct nft_connlimit *priv = nft_obj_data(obj); 144 145 nft_connlimit_do_destroy(ctx, priv); 146 } 147 148 static int nft_connlimit_obj_dump(struct sk_buff *skb, 149 struct nft_object *obj, bool reset) 150 { 151 struct nft_connlimit *priv = nft_obj_data(obj); 152 153 return nft_connlimit_do_dump(skb, priv); 154 } 155 156 static const struct nla_policy nft_connlimit_policy[NFTA_CONNLIMIT_MAX + 1] = { 157 [NFTA_CONNLIMIT_COUNT] = { .type = NLA_U32 }, 158 [NFTA_CONNLIMIT_FLAGS] = { .type = NLA_U32 }, 159 }; 160 161 static struct nft_object_type nft_connlimit_obj_type; 162 static const struct nft_object_ops nft_connlimit_obj_ops = { 163 .type = &nft_connlimit_obj_type, 164 .size = sizeof(struct nft_connlimit), 165 .eval = nft_connlimit_obj_eval, 166 .init = nft_connlimit_obj_init, 167 .destroy = nft_connlimit_obj_destroy, 168 .dump = nft_connlimit_obj_dump, 169 }; 170 171 static struct nft_object_type nft_connlimit_obj_type __read_mostly = { 172 .type = NFT_OBJECT_CONNLIMIT, 173 .ops = &nft_connlimit_obj_ops, 174 .maxattr = NFTA_CONNLIMIT_MAX, 175 .policy = nft_connlimit_policy, 176 .owner = THIS_MODULE, 177 }; 178 179 static void nft_connlimit_eval(const struct nft_expr *expr, 180 struct nft_regs *regs, 181 const struct nft_pktinfo *pkt) 182 { 183 struct nft_connlimit *priv = nft_expr_priv(expr); 184 185 nft_connlimit_do_eval(priv, regs, pkt, NULL); 186 } 187 188 static int nft_connlimit_dump(struct sk_buff *skb, const struct nft_expr *expr) 189 { 190 struct nft_connlimit *priv = nft_expr_priv(expr); 191 192 return nft_connlimit_do_dump(skb, priv); 193 } 194 195 static int nft_connlimit_init(const struct nft_ctx *ctx, 196 const struct nft_expr *expr, 197 const struct nlattr * const tb[]) 198 { 199 struct nft_connlimit *priv = nft_expr_priv(expr); 200 201 return nft_connlimit_do_init(ctx, tb, priv); 202 } 203 204 static void nft_connlimit_destroy(const struct nft_ctx *ctx, 205 const struct nft_expr *expr) 206 { 207 struct nft_connlimit *priv = nft_expr_priv(expr); 208 209 nft_connlimit_do_destroy(ctx, priv); 210 } 211 212 static int nft_connlimit_clone(struct nft_expr *dst, const struct nft_expr *src) 213 { 214 struct nft_connlimit *priv_dst = nft_expr_priv(dst); 215 struct nft_connlimit *priv_src = nft_expr_priv(src); 216 217 priv_dst->list = kmalloc(sizeof(*priv_dst->list), GFP_ATOMIC); 218 if (!priv_dst->list) 219 return -ENOMEM; 220 221 nf_conncount_list_init(priv_dst->list); 222 priv_dst->limit = priv_src->limit; 223 priv_dst->invert = priv_src->invert; 224 225 return 0; 226 } 227 228 static void nft_connlimit_destroy_clone(const struct nft_ctx *ctx, 229 const struct nft_expr *expr) 230 { 231 struct nft_connlimit *priv = nft_expr_priv(expr); 232 233 nf_conncount_cache_free(priv->list); 234 kfree(priv->list); 235 } 236 237 static bool nft_connlimit_gc(struct net *net, const struct nft_expr *expr) 238 { 239 struct nft_connlimit *priv = nft_expr_priv(expr); 240 bool ret; 241 242 local_bh_disable(); 243 ret = nf_conncount_gc_list(net, priv->list); 244 local_bh_enable(); 245 246 return ret; 247 } 248 249 static struct nft_expr_type nft_connlimit_type; 250 static const struct nft_expr_ops nft_connlimit_ops = { 251 .type = &nft_connlimit_type, 252 .size = NFT_EXPR_SIZE(sizeof(struct nft_connlimit)), 253 .eval = nft_connlimit_eval, 254 .init = nft_connlimit_init, 255 .destroy = nft_connlimit_destroy, 256 .clone = nft_connlimit_clone, 257 .destroy_clone = nft_connlimit_destroy_clone, 258 .dump = nft_connlimit_dump, 259 .gc = nft_connlimit_gc, 260 .reduce = NFT_REDUCE_READONLY, 261 }; 262 263 static struct nft_expr_type nft_connlimit_type __read_mostly = { 264 .name = "connlimit", 265 .ops = &nft_connlimit_ops, 266 .policy = nft_connlimit_policy, 267 .maxattr = NFTA_CONNLIMIT_MAX, 268 .flags = NFT_EXPR_STATEFUL | NFT_EXPR_GC, 269 .owner = THIS_MODULE, 270 }; 271 272 static int __init nft_connlimit_module_init(void) 273 { 274 int err; 275 276 err = nft_register_obj(&nft_connlimit_obj_type); 277 if (err < 0) 278 return err; 279 280 err = nft_register_expr(&nft_connlimit_type); 281 if (err < 0) 282 goto err1; 283 284 return 0; 285 err1: 286 nft_unregister_obj(&nft_connlimit_obj_type); 287 return err; 288 } 289 290 static void __exit nft_connlimit_module_exit(void) 291 { 292 nft_unregister_expr(&nft_connlimit_type); 293 nft_unregister_obj(&nft_connlimit_obj_type); 294 } 295 296 module_init(nft_connlimit_module_init); 297 module_exit(nft_connlimit_module_exit); 298 299 MODULE_LICENSE("GPL"); 300 MODULE_AUTHOR("Pablo Neira Ayuso"); 301 MODULE_ALIAS_NFT_EXPR("connlimit"); 302 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT); 303 MODULE_DESCRIPTION("nftables connlimit rule support"); 304