1
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 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;
93err_netns:
94 kfree(priv->list);
95
96 return err;
97}
98
99static 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
107static 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
118nla_put_failure:
119 return -1;
120}
121
122static 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
131static 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
140static 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
148static 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
156static 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
161static struct nft_object_type nft_connlimit_obj_type;
162static 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
171static 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
179static 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
188static 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
195static 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
204static 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
212static 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
228static 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
237static 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
249static struct nft_expr_type nft_connlimit_type;
250static 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
263static 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
272static 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;
285err1:
286 nft_unregister_obj(&nft_connlimit_obj_type);
287 return err;
288}
289
290static 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
296module_init(nft_connlimit_module_init);
297module_exit(nft_connlimit_module_exit);
298
299MODULE_LICENSE("GPL");
300MODULE_AUTHOR("Pablo Neira Ayuso");
301MODULE_ALIAS_NFT_EXPR("connlimit");
302MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT);
303MODULE_DESCRIPTION("nftables connlimit rule support");
304
