1/*
  2 * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License version 2 as
  6 * published by the Free Software Foundation.
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/init.h>
 11#include <linux/module.h>
 12#include <linux/atomic.h>
 13#include <linux/netlink.h>
 14#include <linux/netfilter.h>
 15#include <linux/netfilter/nf_tables.h>
 16#include <net/netfilter/nf_tables.h>
 17
 18struct nft_quota {
 19	u64		quota;
 20	unsigned long	flags;
 21	atomic64_t	consumed;
 22};
 23
 24static inline bool nft_overquota(struct nft_quota *priv,
 25				 const struct sk_buff *skb)
 26{
 27	return atomic64_add_return(skb->len, &priv->consumed) >= priv->quota;
 28}
 29
 30static inline bool nft_quota_invert(struct nft_quota *priv)
 31{
 32	return priv->flags & NFT_QUOTA_F_INV;
 33}
 34
 35static inline void nft_quota_do_eval(struct nft_quota *priv,
 36				     struct nft_regs *regs,
 37				     const struct nft_pktinfo *pkt)
 38{
 39	if (nft_overquota(priv, pkt->skb) ^ nft_quota_invert(priv))
 40		regs->verdict.code = NFT_BREAK;
 41}
 42
 43static const struct nla_policy nft_quota_policy[NFTA_QUOTA_MAX + 1] = {
 44	[NFTA_QUOTA_BYTES]	= { .type = NLA_U64 },
 45	[NFTA_QUOTA_FLAGS]	= { .type = NLA_U32 },
 46	[NFTA_QUOTA_CONSUMED]	= { .type = NLA_U64 },
 47};
 48
 49#define NFT_QUOTA_DEPLETED_BIT	1	/* From NFT_QUOTA_F_DEPLETED. */
 50
 51static void nft_quota_obj_eval(struct nft_object *obj,
 52			       struct nft_regs *regs,
 53			       const struct nft_pktinfo *pkt)
 54{
 55	struct nft_quota *priv = nft_obj_data(obj);
 56	bool overquota;
 57
 58	overquota = nft_overquota(priv, pkt->skb);
 59	if (overquota ^ nft_quota_invert(priv))
 60		regs->verdict.code = NFT_BREAK;
 61
 62	if (overquota &&
 63	    !test_and_set_bit(NFT_QUOTA_DEPLETED_BIT, &priv->flags))
 64		nft_obj_notify(nft_net(pkt), obj->table, obj, 0, 0,
 65			       NFT_MSG_NEWOBJ, nft_pf(pkt), 0, GFP_ATOMIC);
 66}
 67
 68static int nft_quota_do_init(const struct nlattr * const tb[],
 69			     struct nft_quota *priv)
 70{
 71	unsigned long flags = 0;
 72	u64 quota, consumed = 0;
 73
 74	if (!tb[NFTA_QUOTA_BYTES])
 75		return -EINVAL;
 76
 77	quota = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_BYTES]));
 78	if (quota > S64_MAX)
 79		return -EOVERFLOW;
 80
 81	if (tb[NFTA_QUOTA_CONSUMED]) {
 82		consumed = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_CONSUMED]));
 83		if (consumed > quota)
 84			return -EINVAL;
 85	}
 86
 87	if (tb[NFTA_QUOTA_FLAGS]) {
 88		flags = ntohl(nla_get_be32(tb[NFTA_QUOTA_FLAGS]));
 89		if (flags & ~NFT_QUOTA_F_INV)
 90			return -EINVAL;
 91		if (flags & NFT_QUOTA_F_DEPLETED)
 92			return -EOPNOTSUPP;
 93	}
 94
 95	priv->quota = quota;
 96	priv->flags = flags;
 97	atomic64_set(&priv->consumed, consumed);
 98
 99	return 0;
100}
101
102static int nft_quota_obj_init(const struct nlattr * const tb[],
103			      struct nft_object *obj)
104{
105	struct nft_quota *priv = nft_obj_data(obj);
106
107	return nft_quota_do_init(tb, priv);
108}
109
110static int nft_quota_do_dump(struct sk_buff *skb, struct nft_quota *priv,
111			     bool reset)
112{
113	u64 consumed, consumed_cap;
114	u32 flags = priv->flags;
115
116	/* Since we inconditionally increment consumed quota for each packet
117	 * that we see, don't go over the quota boundary in what we send to
118	 * userspace.
119	 */
120	consumed = atomic64_read(&priv->consumed);
121	if (consumed >= priv->quota) {
122		consumed_cap = priv->quota;
123		flags |= NFT_QUOTA_F_DEPLETED;
124	} else {
125		consumed_cap = consumed;
126	}
127
128	if (nla_put_be64(skb, NFTA_QUOTA_BYTES, cpu_to_be64(priv->quota),
129			 NFTA_QUOTA_PAD) ||
130	    nla_put_be64(skb, NFTA_QUOTA_CONSUMED, cpu_to_be64(consumed_cap),
131			 NFTA_QUOTA_PAD) ||
132	    nla_put_be32(skb, NFTA_QUOTA_FLAGS, htonl(flags)))
133		goto nla_put_failure;
134
135	if (reset) {
136		atomic64_sub(consumed, &priv->consumed);
137		clear_bit(NFT_QUOTA_DEPLETED_BIT, &priv->flags);
138	}
139	return 0;
140
141nla_put_failure:
142	return -1;
143}
144
145static int nft_quota_obj_dump(struct sk_buff *skb, struct nft_object *obj,
146			      bool reset)
147{
148	struct nft_quota *priv = nft_obj_data(obj);
149
150	return nft_quota_do_dump(skb, priv, reset);
151}
152
153static struct nft_object_type nft_quota_obj __read_mostly = {
154	.type		= NFT_OBJECT_QUOTA,
155	.size		= sizeof(struct nft_quota),
156	.maxattr	= NFTA_QUOTA_MAX,
157	.policy		= nft_quota_policy,
158	.init		= nft_quota_obj_init,
159	.eval		= nft_quota_obj_eval,
160	.dump		= nft_quota_obj_dump,
161	.owner		= THIS_MODULE,
162};
163
164static void nft_quota_eval(const struct nft_expr *expr,
165			   struct nft_regs *regs,
166			   const struct nft_pktinfo *pkt)
167{
168	struct nft_quota *priv = nft_expr_priv(expr);
169
170	nft_quota_do_eval(priv, regs, pkt);
171}
172
173static int nft_quota_init(const struct nft_ctx *ctx,
174			  const struct nft_expr *expr,
175			  const struct nlattr * const tb[])
176{
177	struct nft_quota *priv = nft_expr_priv(expr);
178
179	return nft_quota_do_init(tb, priv);
180}
181
182static int nft_quota_dump(struct sk_buff *skb, const struct nft_expr *expr)
183{
184	struct nft_quota *priv = nft_expr_priv(expr);
185
186	return nft_quota_do_dump(skb, priv, false);
187}
188
189static struct nft_expr_type nft_quota_type;
190static const struct nft_expr_ops nft_quota_ops = {
191	.type		= &nft_quota_type,
192	.size		= NFT_EXPR_SIZE(sizeof(struct nft_quota)),
193	.eval		= nft_quota_eval,
194	.init		= nft_quota_init,
195	.dump		= nft_quota_dump,
196};
197
198static struct nft_expr_type nft_quota_type __read_mostly = {
199	.name		= "quota",
200	.ops		= &nft_quota_ops,
201	.policy		= nft_quota_policy,
202	.maxattr	= NFTA_QUOTA_MAX,
203	.flags		= NFT_EXPR_STATEFUL,
204	.owner		= THIS_MODULE,
205};
206
207static int __init nft_quota_module_init(void)
208{
209	int err;
210
211	err = nft_register_obj(&nft_quota_obj);
212	if (err < 0)
213		return err;
214
215	err = nft_register_expr(&nft_quota_type);
216	if (err < 0)
217		goto err1;
218
219	return 0;
220err1:
221	nft_unregister_obj(&nft_quota_obj);
222	return err;
223}
224
225static void __exit nft_quota_module_exit(void)
226{
227	nft_unregister_expr(&nft_quota_type);
228	nft_unregister_obj(&nft_quota_obj);
229}
230
231module_init(nft_quota_module_init);
232module_exit(nft_quota_module_exit);
233
234MODULE_LICENSE("GPL");
235MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
236MODULE_ALIAS_NFT_EXPR("quota");
237MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_QUOTA);