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(skb: pkt->skb, ctinfo: &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(skb: pkt->skb, nhoff: skb_network_offset(skb: pkt->skb), |
41 | l3num: nft_pf(pkt), net: nft_net(pkt), tuple: &tuple)) { |
42 | regs->verdict.code = NF_DROP; |
43 | return; |
44 | } |
45 | |
46 | if (nf_conncount_add(net: nft_net(pkt), list: priv->list, tuple: 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(size: sizeof(*priv->list), GFP_KERNEL_ACCOUNT); |
81 | if (!priv->list) |
82 | return -ENOMEM; |
83 | |
84 | nf_conncount_list_init(list: priv->list); |
85 | priv->limit = limit; |
86 | priv->invert = invert; |
87 | |
88 | err = nf_ct_netns_get(net: ctx->net, nfproto: ctx->family); |
89 | if (err < 0) |
90 | goto err_netns; |
91 | |
92 | return 0; |
93 | err_netns: |
94 | kfree(objp: 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(net: ctx->net, nfproto: ctx->family); |
103 | nf_conncount_cache_free(list: priv->list); |
104 | kfree(objp: 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, attrtype: NFTA_CONNLIMIT_COUNT, htonl(priv->limit))) |
111 | goto nla_put_failure; |
112 | if (priv->invert && |
113 | nla_put_be32(skb, attrtype: 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, |
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 | |
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 | |
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 | |
213 | static int nft_connlimit_clone(struct nft_expr *dst, const struct nft_expr *src) |
214 | { |
215 | struct nft_connlimit *priv_dst = nft_expr_priv(expr: dst); |
216 | struct nft_connlimit *priv_src = nft_expr_priv(expr: src); |
217 | |
218 | priv_dst->list = kmalloc(size: sizeof(*priv_dst->list), GFP_ATOMIC); |
219 | if (!priv_dst->list) |
220 | return -ENOMEM; |
221 | |
222 | nf_conncount_list_init(list: priv_dst->list); |
223 | priv_dst->limit = priv_src->limit; |
224 | priv_dst->invert = priv_src->invert; |
225 | |
226 | return 0; |
227 | } |
228 | |
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(list: priv->list); |
235 | kfree(objp: priv->list); |
236 | } |
237 | |
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, list: 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 | |
273 | static int __init nft_connlimit_module_init(void) |
274 | { |
275 | int err; |
276 | |
277 | err = nft_register_obj(obj_type: &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(obj_type: &nft_connlimit_obj_type); |
288 | return err; |
289 | } |
290 | |
291 | static void __exit nft_connlimit_module_exit(void) |
292 | { |
293 | nft_unregister_expr(&nft_connlimit_type); |
294 | nft_unregister_obj(obj_type: &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 | |