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11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/spinlock.h>
15#include <linux/netlink.h>
16#include <linux/netfilter.h>
17#include <linux/netfilter/nf_tables.h>
18#include <net/netfilter/nf_tables.h>
19
20static DEFINE_SPINLOCK(limit_lock);
21
22struct nft_limit {
23 u64 last;
24 u64 tokens;
25 u64 tokens_max;
26 u64 rate;
27 u64 nsecs;
28 u32 burst;
29 bool invert;
30};
31
32static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost)
33{
34 u64 now, tokens;
35 s64 delta;
36
37 spin_lock_bh(&limit_lock);
38 now = ktime_get_ns();
39 tokens = limit->tokens + now - limit->last;
40 if (tokens > limit->tokens_max)
41 tokens = limit->tokens_max;
42
43 limit->last = now;
44 delta = tokens - cost;
45 if (delta >= 0) {
46 limit->tokens = delta;
47 spin_unlock_bh(&limit_lock);
48 return limit->invert;
49 }
50 limit->tokens = tokens;
51 spin_unlock_bh(&limit_lock);
52 return !limit->invert;
53}
54
55static int nft_limit_init(struct nft_limit *limit,
56 const struct nlattr * const tb[])
57{
58 u64 unit;
59
60 if (tb[NFTA_LIMIT_RATE] == NULL ||
61 tb[NFTA_LIMIT_UNIT] == NULL)
62 return -EINVAL;
63
64 limit->rate = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
65 unit = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
66 limit->nsecs = unit * NSEC_PER_SEC;
67 if (limit->rate == 0 || limit->nsecs < unit)
68 return -EOVERFLOW;
69 limit->tokens = limit->tokens_max = limit->nsecs;
70
71 if (tb[NFTA_LIMIT_BURST]) {
72 u64 rate;
73
74 limit->burst = ntohl(nla_get_be32(tb[NFTA_LIMIT_BURST]));
75
76 rate = limit->rate + limit->burst;
77 if (rate < limit->rate)
78 return -EOVERFLOW;
79
80 limit->rate = rate;
81 }
82 if (tb[NFTA_LIMIT_FLAGS]) {
83 u32 flags = ntohl(nla_get_be32(tb[NFTA_LIMIT_FLAGS]));
84
85 if (flags & NFT_LIMIT_F_INV)
86 limit->invert = true;
87 }
88 limit->last = ktime_get_ns();
89
90 return 0;
91}
92
93static int nft_limit_dump(struct sk_buff *skb, const struct nft_limit *limit,
94 enum nft_limit_type type)
95{
96 u32 flags = limit->invert ? NFT_LIMIT_F_INV : 0;
97 u64 secs = div_u64(limit->nsecs, NSEC_PER_SEC);
98 u64 rate = limit->rate - limit->burst;
99
100 if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(rate),
101 NFTA_LIMIT_PAD) ||
102 nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs),
103 NFTA_LIMIT_PAD) ||
104 nla_put_be32(skb, NFTA_LIMIT_BURST, htonl(limit->burst)) ||
105 nla_put_be32(skb, NFTA_LIMIT_TYPE, htonl(type)) ||
106 nla_put_be32(skb, NFTA_LIMIT_FLAGS, htonl(flags)))
107 goto nla_put_failure;
108 return 0;
109
110nla_put_failure:
111 return -1;
112}
113
114struct nft_limit_pkts {
115 struct nft_limit limit;
116 u64 cost;
117};
118
119static void nft_limit_pkts_eval(const struct nft_expr *expr,
120 struct nft_regs *regs,
121 const struct nft_pktinfo *pkt)
122{
123 struct nft_limit_pkts *priv = nft_expr_priv(expr);
124
125 if (nft_limit_eval(&priv->limit, priv->cost))
126 regs->verdict.code = NFT_BREAK;
127}
128
129static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
130 [NFTA_LIMIT_RATE] = { .type = NLA_U64 },
131 [NFTA_LIMIT_UNIT] = { .type = NLA_U64 },
132 [NFTA_LIMIT_BURST] = { .type = NLA_U32 },
133 [NFTA_LIMIT_TYPE] = { .type = NLA_U32 },
134 [NFTA_LIMIT_FLAGS] = { .type = NLA_U32 },
135};
136
137static int nft_limit_pkts_init(const struct nft_ctx *ctx,
138 const struct nft_expr *expr,
139 const struct nlattr * const tb[])
140{
141 struct nft_limit_pkts *priv = nft_expr_priv(expr);
142 int err;
143
144 err = nft_limit_init(&priv->limit, tb);
145 if (err < 0)
146 return err;
147
148 priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate);
149 return 0;
150}
151
152static int nft_limit_pkts_dump(struct sk_buff *skb, const struct nft_expr *expr)
153{
154 const struct nft_limit_pkts *priv = nft_expr_priv(expr);
155
156 return nft_limit_dump(skb, &priv->limit, NFT_LIMIT_PKTS);
157}
158
159static struct nft_expr_type nft_limit_type;
160static const struct nft_expr_ops nft_limit_pkts_ops = {
161 .type = &nft_limit_type,
162 .size = NFT_EXPR_SIZE(sizeof(struct nft_limit_pkts)),
163 .eval = nft_limit_pkts_eval,
164 .init = nft_limit_pkts_init,
165 .dump = nft_limit_pkts_dump,
166};
167
168static void nft_limit_pkt_bytes_eval(const struct nft_expr *expr,
169 struct nft_regs *regs,
170 const struct nft_pktinfo *pkt)
171{
172 struct nft_limit *priv = nft_expr_priv(expr);
173 u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate);
174
175 if (nft_limit_eval(priv, cost))
176 regs->verdict.code = NFT_BREAK;
177}
178
179static int nft_limit_pkt_bytes_init(const struct nft_ctx *ctx,
180 const struct nft_expr *expr,
181 const struct nlattr * const tb[])
182{
183 struct nft_limit *priv = nft_expr_priv(expr);
184
185 return nft_limit_init(priv, tb);
186}
187
188static int nft_limit_pkt_bytes_dump(struct sk_buff *skb,
189 const struct nft_expr *expr)
190{
191 const struct nft_limit *priv = nft_expr_priv(expr);
192
193 return nft_limit_dump(skb, priv, NFT_LIMIT_PKT_BYTES);
194}
195
196static const struct nft_expr_ops nft_limit_pkt_bytes_ops = {
197 .type = &nft_limit_type,
198 .size = NFT_EXPR_SIZE(sizeof(struct nft_limit)),
199 .eval = nft_limit_pkt_bytes_eval,
200 .init = nft_limit_pkt_bytes_init,
201 .dump = nft_limit_pkt_bytes_dump,
202};
203
204static const struct nft_expr_ops *
205nft_limit_select_ops(const struct nft_ctx *ctx,
206 const struct nlattr * const tb[])
207{
208 if (tb[NFTA_LIMIT_TYPE] == NULL)
209 return &nft_limit_pkts_ops;
210
211 switch (ntohl(nla_get_be32(tb[NFTA_LIMIT_TYPE]))) {
212 case NFT_LIMIT_PKTS:
213 return &nft_limit_pkts_ops;
214 case NFT_LIMIT_PKT_BYTES:
215 return &nft_limit_pkt_bytes_ops;
216 }
217 return ERR_PTR(-EOPNOTSUPP);
218}
219
220static struct nft_expr_type nft_limit_type __read_mostly = {
221 .name = "limit",
222 .select_ops = nft_limit_select_ops,
223 .policy = nft_limit_policy,
224 .maxattr = NFTA_LIMIT_MAX,
225 .flags = NFT_EXPR_STATEFUL,
226 .owner = THIS_MODULE,
227};
228
229static int __init nft_limit_module_init(void)
230{
231 return nft_register_expr(&nft_limit_type);
232}
233
234static void __exit nft_limit_module_exit(void)
235{
236 nft_unregister_expr(&nft_limit_type);
237}
238
239module_init(nft_limit_module_init);
240module_exit(nft_limit_module_exit);
241
242MODULE_LICENSE("GPL");
243MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
244MODULE_ALIAS_NFT_EXPR("limit");
245
