1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
4  */
5 
6 #include <linux/kernel.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/atomic.h>
10 #include <linux/netlink.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter/nf_tables.h>
13 #include <net/netfilter/nf_tables.h>
14 
15 struct nft_quota {
16 	atomic64_t	quota;
17 	unsigned long	flags;
18 	atomic64_t	*consumed;
19 };
20 
nft_overquota(struct nft_quota * priv,const struct sk_buff * skb)21 static inline bool nft_overquota(struct nft_quota *priv,
22 				 const struct sk_buff *skb)
23 {
24 	return atomic64_add_return(skb->len, priv->consumed) >=
25 	       atomic64_read(&priv->quota);
26 }
27 
nft_quota_invert(struct nft_quota * priv)28 static inline bool nft_quota_invert(struct nft_quota *priv)
29 {
30 	return priv->flags & NFT_QUOTA_F_INV;
31 }
32 
nft_quota_do_eval(struct nft_quota * priv,struct nft_regs * regs,const struct nft_pktinfo * pkt)33 static inline void nft_quota_do_eval(struct nft_quota *priv,
34 				     struct nft_regs *regs,
35 				     const struct nft_pktinfo *pkt)
36 {
37 	if (nft_overquota(priv, pkt->skb) ^ nft_quota_invert(priv))
38 		regs->verdict.code = NFT_BREAK;
39 }
40 
41 static const struct nla_policy nft_quota_policy[NFTA_QUOTA_MAX + 1] = {
42 	[NFTA_QUOTA_BYTES]	= { .type = NLA_U64 },
43 	[NFTA_QUOTA_FLAGS]	= { .type = NLA_U32 },
44 	[NFTA_QUOTA_CONSUMED]	= { .type = NLA_U64 },
45 };
46 
47 #define NFT_QUOTA_DEPLETED_BIT	1	/* From NFT_QUOTA_F_DEPLETED. */
48 
nft_quota_obj_eval(struct nft_object * obj,struct nft_regs * regs,const struct nft_pktinfo * pkt)49 static void nft_quota_obj_eval(struct nft_object *obj,
50 			       struct nft_regs *regs,
51 			       const struct nft_pktinfo *pkt)
52 {
53 	struct nft_quota *priv = nft_obj_data(obj);
54 	bool overquota;
55 
56 	overquota = nft_overquota(priv, pkt->skb);
57 	if (overquota ^ nft_quota_invert(priv))
58 		regs->verdict.code = NFT_BREAK;
59 
60 	if (overquota &&
61 	    !test_and_set_bit(NFT_QUOTA_DEPLETED_BIT, &priv->flags))
62 		nft_obj_notify(nft_net(pkt), obj->key.table, obj, 0, 0,
63 			       NFT_MSG_NEWOBJ, 0, nft_pf(pkt), 0, GFP_ATOMIC);
64 }
65 
nft_quota_do_init(const struct nlattr * const tb[],struct nft_quota * priv)66 static int nft_quota_do_init(const struct nlattr * const tb[],
67 			     struct nft_quota *priv)
68 {
69 	unsigned long flags = 0;
70 	u64 quota, consumed = 0;
71 
72 	if (!tb[NFTA_QUOTA_BYTES])
73 		return -EINVAL;
74 
75 	quota = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_BYTES]));
76 	if (quota > S64_MAX)
77 		return -EOVERFLOW;
78 
79 	if (tb[NFTA_QUOTA_CONSUMED]) {
80 		consumed = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_CONSUMED]));
81 		if (consumed > quota)
82 			return -EINVAL;
83 	}
84 
85 	if (tb[NFTA_QUOTA_FLAGS]) {
86 		flags = ntohl(nla_get_be32(tb[NFTA_QUOTA_FLAGS]));
87 		if (flags & ~NFT_QUOTA_F_INV)
88 			return -EINVAL;
89 		if (flags & NFT_QUOTA_F_DEPLETED)
90 			return -EOPNOTSUPP;
91 	}
92 
93 	priv->consumed = kmalloc(sizeof(*priv->consumed), GFP_KERNEL_ACCOUNT);
94 	if (!priv->consumed)
95 		return -ENOMEM;
96 
97 	atomic64_set(&priv->quota, quota);
98 	priv->flags = flags;
99 	atomic64_set(priv->consumed, consumed);
100 
101 	return 0;
102 }
103 
nft_quota_do_destroy(const struct nft_ctx * ctx,struct nft_quota * priv)104 static void nft_quota_do_destroy(const struct nft_ctx *ctx,
105 				 struct nft_quota *priv)
106 {
107 	kfree(priv->consumed);
108 }
109 
nft_quota_obj_init(const struct nft_ctx * ctx,const struct nlattr * const tb[],struct nft_object * obj)110 static int nft_quota_obj_init(const struct nft_ctx *ctx,
111 			      const struct nlattr * const tb[],
112 			      struct nft_object *obj)
113 {
114 	struct nft_quota *priv = nft_obj_data(obj);
115 
116 	return nft_quota_do_init(tb, priv);
117 }
118 
nft_quota_obj_update(struct nft_object * obj,struct nft_object * newobj)119 static void nft_quota_obj_update(struct nft_object *obj,
120 				 struct nft_object *newobj)
121 {
122 	struct nft_quota *newpriv = nft_obj_data(newobj);
123 	struct nft_quota *priv = nft_obj_data(obj);
124 	u64 newquota;
125 
126 	newquota = atomic64_read(&newpriv->quota);
127 	atomic64_set(&priv->quota, newquota);
128 	priv->flags = newpriv->flags;
129 }
130 
nft_quota_do_dump(struct sk_buff * skb,struct nft_quota * priv,bool reset)131 static int nft_quota_do_dump(struct sk_buff *skb, struct nft_quota *priv,
132 			     bool reset)
133 {
134 	u64 consumed, consumed_cap, quota;
135 	u32 flags = priv->flags;
136 
137 	/* Since we inconditionally increment consumed quota for each packet
138 	 * that we see, don't go over the quota boundary in what we send to
139 	 * userspace.
140 	 */
141 	consumed = atomic64_read(priv->consumed);
142 	quota = atomic64_read(&priv->quota);
143 	if (consumed >= quota) {
144 		consumed_cap = quota;
145 		flags |= NFT_QUOTA_F_DEPLETED;
146 	} else {
147 		consumed_cap = consumed;
148 	}
149 
150 	if (nla_put_be64(skb, NFTA_QUOTA_BYTES, cpu_to_be64(quota),
151 			 NFTA_QUOTA_PAD) ||
152 	    nla_put_be64(skb, NFTA_QUOTA_CONSUMED, cpu_to_be64(consumed_cap),
153 			 NFTA_QUOTA_PAD) ||
154 	    nla_put_be32(skb, NFTA_QUOTA_FLAGS, htonl(flags)))
155 		goto nla_put_failure;
156 
157 	if (reset) {
158 		atomic64_sub(consumed, priv->consumed);
159 		clear_bit(NFT_QUOTA_DEPLETED_BIT, &priv->flags);
160 	}
161 	return 0;
162 
163 nla_put_failure:
164 	return -1;
165 }
166 
nft_quota_obj_dump(struct sk_buff * skb,struct nft_object * obj,bool reset)167 static int nft_quota_obj_dump(struct sk_buff *skb, struct nft_object *obj,
168 			      bool reset)
169 {
170 	struct nft_quota *priv = nft_obj_data(obj);
171 
172 	return nft_quota_do_dump(skb, priv, reset);
173 }
174 
nft_quota_obj_destroy(const struct nft_ctx * ctx,struct nft_object * obj)175 static void nft_quota_obj_destroy(const struct nft_ctx *ctx,
176 				  struct nft_object *obj)
177 {
178 	struct nft_quota *priv = nft_obj_data(obj);
179 
180 	return nft_quota_do_destroy(ctx, priv);
181 }
182 
183 static struct nft_object_type nft_quota_obj_type;
184 static const struct nft_object_ops nft_quota_obj_ops = {
185 	.type		= &nft_quota_obj_type,
186 	.size		= sizeof(struct nft_quota),
187 	.init		= nft_quota_obj_init,
188 	.destroy	= nft_quota_obj_destroy,
189 	.eval		= nft_quota_obj_eval,
190 	.dump		= nft_quota_obj_dump,
191 	.update		= nft_quota_obj_update,
192 };
193 
194 static struct nft_object_type nft_quota_obj_type __read_mostly = {
195 	.type		= NFT_OBJECT_QUOTA,
196 	.ops		= &nft_quota_obj_ops,
197 	.maxattr	= NFTA_QUOTA_MAX,
198 	.policy		= nft_quota_policy,
199 	.owner		= THIS_MODULE,
200 };
201 
nft_quota_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)202 static void nft_quota_eval(const struct nft_expr *expr,
203 			   struct nft_regs *regs,
204 			   const struct nft_pktinfo *pkt)
205 {
206 	struct nft_quota *priv = nft_expr_priv(expr);
207 
208 	nft_quota_do_eval(priv, regs, pkt);
209 }
210 
nft_quota_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])211 static int nft_quota_init(const struct nft_ctx *ctx,
212 			  const struct nft_expr *expr,
213 			  const struct nlattr * const tb[])
214 {
215 	struct nft_quota *priv = nft_expr_priv(expr);
216 
217 	return nft_quota_do_init(tb, priv);
218 }
219 
nft_quota_dump(struct sk_buff * skb,const struct nft_expr * expr,bool reset)220 static int nft_quota_dump(struct sk_buff *skb,
221 			  const struct nft_expr *expr, bool reset)
222 {
223 	struct nft_quota *priv = nft_expr_priv(expr);
224 
225 	return nft_quota_do_dump(skb, priv, reset);
226 }
227 
nft_quota_destroy(const struct nft_ctx * ctx,const struct nft_expr * expr)228 static void nft_quota_destroy(const struct nft_ctx *ctx,
229 			      const struct nft_expr *expr)
230 {
231 	struct nft_quota *priv = nft_expr_priv(expr);
232 
233 	return nft_quota_do_destroy(ctx, priv);
234 }
235 
nft_quota_clone(struct nft_expr * dst,const struct nft_expr * src,gfp_t gfp)236 static int nft_quota_clone(struct nft_expr *dst, const struct nft_expr *src, gfp_t gfp)
237 {
238 	struct nft_quota *priv_dst = nft_expr_priv(dst);
239 	struct nft_quota *priv_src = nft_expr_priv(src);
240 
241 	priv_dst->quota = priv_src->quota;
242 	priv_dst->flags = priv_src->flags;
243 
244 	priv_dst->consumed = kmalloc(sizeof(*priv_dst->consumed), gfp);
245 	if (!priv_dst->consumed)
246 		return -ENOMEM;
247 
248 	*priv_dst->consumed = *priv_src->consumed;
249 
250 	return 0;
251 }
252 
253 static struct nft_expr_type nft_quota_type;
254 static const struct nft_expr_ops nft_quota_ops = {
255 	.type		= &nft_quota_type,
256 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_quota)),
257 	.eval		= nft_quota_eval,
258 	.init		= nft_quota_init,
259 	.destroy	= nft_quota_destroy,
260 	.clone		= nft_quota_clone,
261 	.dump		= nft_quota_dump,
262 	.reduce		= NFT_REDUCE_READONLY,
263 };
264 
265 static struct nft_expr_type nft_quota_type __read_mostly = {
266 	.name		= "quota",
267 	.ops		= &nft_quota_ops,
268 	.policy		= nft_quota_policy,
269 	.maxattr	= NFTA_QUOTA_MAX,
270 	.flags		= NFT_EXPR_STATEFUL,
271 	.owner		= THIS_MODULE,
272 };
273 
nft_quota_module_init(void)274 static int __init nft_quota_module_init(void)
275 {
276 	int err;
277 
278 	err = nft_register_obj(&nft_quota_obj_type);
279 	if (err < 0)
280 		return err;
281 
282 	err = nft_register_expr(&nft_quota_type);
283 	if (err < 0)
284 		goto err1;
285 
286 	return 0;
287 err1:
288 	nft_unregister_obj(&nft_quota_obj_type);
289 	return err;
290 }
291 
nft_quota_module_exit(void)292 static void __exit nft_quota_module_exit(void)
293 {
294 	nft_unregister_expr(&nft_quota_type);
295 	nft_unregister_obj(&nft_quota_obj_type);
296 }
297 
298 module_init(nft_quota_module_init);
299 module_exit(nft_quota_module_exit);
300 
301 MODULE_LICENSE("GPL");
302 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
303 MODULE_ALIAS_NFT_EXPR("quota");
304 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_QUOTA);
305 MODULE_DESCRIPTION("Netfilter nftables quota module");
306