net/netfilter/nft_quota.c

   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
  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
  28 static inline bool nft_quota_invert(struct nft_quota *priv)
  29 {
  30         return priv->flags & NFT_QUOTA_F_INV;
  31 }
  32
  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
  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
  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
 104 static void nft_quota_do_destroy(const struct nft_ctx *ctx,
 105                                  struct nft_quota *priv)
 106 {
 107         kfree(priv->consumed);
 108 }
 109
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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");