net/netfilter/nft_quota.c

   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
  18 struct nft_quota {
  19         u64             quota;
  20         unsigned long   flags;
  21         atomic64_t      consumed;
  22 };
  23
  24 static 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
  30 static inline bool nft_quota_invert(struct nft_quota *priv)
  31 {
  32         return priv->flags & NFT_QUOTA_F_INV;
  33 }
  34
  35 static 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
  43 static 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
  51 static 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
  68 static 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
 102 static int nft_quota_obj_init(const struct nft_ctx *ctx,
 103                               const struct nlattr * const tb[],
 104                               struct nft_object *obj)
 105 {
 106         struct nft_quota *priv = nft_obj_data(obj);
 107
 108         return nft_quota_do_init(tb, priv);
 109 }
 110
 111 static int nft_quota_do_dump(struct sk_buff *skb, struct nft_quota *priv,
 112                              bool reset)
 113 {
 114         u64 consumed, consumed_cap;
 115         u32 flags = priv->flags;
 116
 117         /* Since we inconditionally increment consumed quota for each packet
 118          * that we see, don't go over the quota boundary in what we send to
 119          * userspace.
 120          */
 121         consumed = atomic64_read(&priv->consumed);
 122         if (consumed >= priv->quota) {
 123                 consumed_cap = priv->quota;
 124                 flags |= NFT_QUOTA_F_DEPLETED;
 125         } else {
 126                 consumed_cap = consumed;
 127         }
 128
 129         if (nla_put_be64(skb, NFTA_QUOTA_BYTES, cpu_to_be64(priv->quota),
 130                          NFTA_QUOTA_PAD) ||
 131             nla_put_be64(skb, NFTA_QUOTA_CONSUMED, cpu_to_be64(consumed_cap),
 132                          NFTA_QUOTA_PAD) ||
 133             nla_put_be32(skb, NFTA_QUOTA_FLAGS, htonl(flags)))
 134                 goto nla_put_failure;
 135
 136         if (reset) {
 137                 atomic64_sub(consumed, &priv->consumed);
 138                 clear_bit(NFT_QUOTA_DEPLETED_BIT, &priv->flags);
 139         }
 140         return 0;
 141
 142 nla_put_failure:
 143         return -1;
 144 }
 145
 146 static int nft_quota_obj_dump(struct sk_buff *skb, struct nft_object *obj,
 147                               bool reset)
 148 {
 149         struct nft_quota *priv = nft_obj_data(obj);
 150
 151         return nft_quota_do_dump(skb, priv, reset);
 152 }
 153
 154 static struct nft_object_type nft_quota_obj __read_mostly = {
 155         .type           = NFT_OBJECT_QUOTA,
 156         .size           = sizeof(struct nft_quota),
 157         .maxattr        = NFTA_QUOTA_MAX,
 158         .policy         = nft_quota_policy,
 159         .init           = nft_quota_obj_init,
 160         .eval           = nft_quota_obj_eval,
 161         .dump           = nft_quota_obj_dump,
 162         .owner          = THIS_MODULE,
 163 };
 164
 165 static void nft_quota_eval(const struct nft_expr *expr,
 166                            struct nft_regs *regs,
 167                            const struct nft_pktinfo *pkt)
 168 {
 169         struct nft_quota *priv = nft_expr_priv(expr);
 170
 171         nft_quota_do_eval(priv, regs, pkt);
 172 }
 173
 174 static int nft_quota_init(const struct nft_ctx *ctx,
 175                           const struct nft_expr *expr,
 176                           const struct nlattr * const tb[])
 177 {
 178         struct nft_quota *priv = nft_expr_priv(expr);
 179
 180         return nft_quota_do_init(tb, priv);
 181 }
 182
 183 static int nft_quota_dump(struct sk_buff *skb, const struct nft_expr *expr)
 184 {
 185         struct nft_quota *priv = nft_expr_priv(expr);
 186
 187         return nft_quota_do_dump(skb, priv, false);
 188 }
 189
 190 static struct nft_expr_type nft_quota_type;
 191 static const struct nft_expr_ops nft_quota_ops = {
 192         .type           = &nft_quota_type,
 193         .size           = NFT_EXPR_SIZE(sizeof(struct nft_quota)),
 194         .eval           = nft_quota_eval,
 195         .init           = nft_quota_init,
 196         .dump           = nft_quota_dump,
 197 };
 198
 199 static struct nft_expr_type nft_quota_type __read_mostly = {
 200         .name           = "quota",
 201         .ops            = &nft_quota_ops,
 202         .policy         = nft_quota_policy,
 203         .maxattr        = NFTA_QUOTA_MAX,
 204         .flags          = NFT_EXPR_STATEFUL,
 205         .owner          = THIS_MODULE,
 206 };
 207
 208 static int __init nft_quota_module_init(void)
 209 {
 210         int err;
 211
 212         err = nft_register_obj(&nft_quota_obj);
 213         if (err < 0)
 214                 return err;
 215
 216         err = nft_register_expr(&nft_quota_type);
 217         if (err < 0)
 218                 goto err1;
 219
 220         return 0;
 221 err1:
 222         nft_unregister_obj(&nft_quota_obj);
 223         return err;
 224 }
 225
 226 static void __exit nft_quota_module_exit(void)
 227 {
 228         nft_unregister_expr(&nft_quota_type);
 229         nft_unregister_obj(&nft_quota_obj);
 230 }
 231
 232 module_init(nft_quota_module_init);
 233 module_exit(nft_quota_module_exit);
 234
 235 MODULE_LICENSE("GPL");
 236 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 237 MODULE_ALIAS_NFT_EXPR("quota");
 238 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_QUOTA);