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
nft_connlimit_do_eval(struct nft_connlimit * priv,struct nft_regs * regs,const struct nft_pktinfo * pkt,const struct nft_set_ext * ext)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
nft_connlimit_do_init(const struct nft_ctx * ctx,const struct nlattr * const tb[],struct nft_connlimit * priv)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
nft_connlimit_do_destroy(const struct nft_ctx * ctx,struct nft_connlimit * priv)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
nft_connlimit_do_dump(struct sk_buff * skb,struct nft_connlimit * priv)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
nft_connlimit_obj_eval(struct nft_object * obj,struct nft_regs * regs,const struct nft_pktinfo * pkt)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
nft_connlimit_obj_init(const struct nft_ctx * ctx,const struct nlattr * const tb[],struct nft_object * obj)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
nft_connlimit_obj_destroy(const struct nft_ctx * ctx,struct nft_object * obj)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
nft_connlimit_obj_dump(struct sk_buff * skb,struct nft_object * obj,bool reset)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
nft_connlimit_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)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
nft_connlimit_dump(struct sk_buff * skb,const struct nft_expr * expr,bool reset)188 static int nft_connlimit_dump(struct sk_buff *skb,
189 const struct nft_expr *expr, bool reset)
190 {
191 struct nft_connlimit *priv = nft_expr_priv(expr);
192
193 return nft_connlimit_do_dump(skb, priv);
194 }
195
nft_connlimit_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])196 static int nft_connlimit_init(const struct nft_ctx *ctx,
197 const struct nft_expr *expr,
198 const struct nlattr * const tb[])
199 {
200 struct nft_connlimit *priv = nft_expr_priv(expr);
201
202 return nft_connlimit_do_init(ctx, tb, priv);
203 }
204
nft_connlimit_destroy(const struct nft_ctx * ctx,const struct nft_expr * expr)205 static void nft_connlimit_destroy(const struct nft_ctx *ctx,
206 const struct nft_expr *expr)
207 {
208 struct nft_connlimit *priv = nft_expr_priv(expr);
209
210 nft_connlimit_do_destroy(ctx, priv);
211 }
212
nft_connlimit_clone(struct nft_expr * dst,const struct nft_expr * src,gfp_t gfp)213 static int nft_connlimit_clone(struct nft_expr *dst, const struct nft_expr *src, gfp_t gfp)
214 {
215 struct nft_connlimit *priv_dst = nft_expr_priv(dst);
216 struct nft_connlimit *priv_src = nft_expr_priv(src);
217
218 priv_dst->list = kmalloc(sizeof(*priv_dst->list), gfp);
219 if (!priv_dst->list)
220 return -ENOMEM;
221
222 nf_conncount_list_init(priv_dst->list);
223 priv_dst->limit = priv_src->limit;
224 priv_dst->invert = priv_src->invert;
225
226 return 0;
227 }
228
nft_connlimit_destroy_clone(const struct nft_ctx * ctx,const struct nft_expr * expr)229 static void nft_connlimit_destroy_clone(const struct nft_ctx *ctx,
230 const struct nft_expr *expr)
231 {
232 struct nft_connlimit *priv = nft_expr_priv(expr);
233
234 nf_conncount_cache_free(priv->list);
235 kfree(priv->list);
236 }
237
nft_connlimit_gc(struct net * net,const struct nft_expr * expr)238 static bool nft_connlimit_gc(struct net *net, const struct nft_expr *expr)
239 {
240 struct nft_connlimit *priv = nft_expr_priv(expr);
241 bool ret;
242
243 local_bh_disable();
244 ret = nf_conncount_gc_list(net, priv->list);
245 local_bh_enable();
246
247 return ret;
248 }
249
250 static struct nft_expr_type nft_connlimit_type;
251 static const struct nft_expr_ops nft_connlimit_ops = {
252 .type = &nft_connlimit_type,
253 .size = NFT_EXPR_SIZE(sizeof(struct nft_connlimit)),
254 .eval = nft_connlimit_eval,
255 .init = nft_connlimit_init,
256 .destroy = nft_connlimit_destroy,
257 .clone = nft_connlimit_clone,
258 .destroy_clone = nft_connlimit_destroy_clone,
259 .dump = nft_connlimit_dump,
260 .gc = nft_connlimit_gc,
261 .reduce = NFT_REDUCE_READONLY,
262 };
263
264 static struct nft_expr_type nft_connlimit_type __read_mostly = {
265 .name = "connlimit",
266 .ops = &nft_connlimit_ops,
267 .policy = nft_connlimit_policy,
268 .maxattr = NFTA_CONNLIMIT_MAX,
269 .flags = NFT_EXPR_STATEFUL | NFT_EXPR_GC,
270 .owner = THIS_MODULE,
271 };
272
nft_connlimit_module_init(void)273 static int __init nft_connlimit_module_init(void)
274 {
275 int err;
276
277 err = nft_register_obj(&nft_connlimit_obj_type);
278 if (err < 0)
279 return err;
280
281 err = nft_register_expr(&nft_connlimit_type);
282 if (err < 0)
283 goto err1;
284
285 return 0;
286 err1:
287 nft_unregister_obj(&nft_connlimit_obj_type);
288 return err;
289 }
290
nft_connlimit_module_exit(void)291 static void __exit nft_connlimit_module_exit(void)
292 {
293 nft_unregister_expr(&nft_connlimit_type);
294 nft_unregister_obj(&nft_connlimit_obj_type);
295 }
296
297 module_init(nft_connlimit_module_init);
298 module_exit(nft_connlimit_module_exit);
299
300 MODULE_LICENSE("GPL");
301 MODULE_AUTHOR("Pablo Neira Ayuso");
302 MODULE_ALIAS_NFT_EXPR("connlimit");
303 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT);
304 MODULE_DESCRIPTION("nftables connlimit rule support");
305