net/netfilter/nft_dynset.c

   1 /*
   2  * Copyright (c) 2015 Patrick McHardy <kaber@trash.net>
   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
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/init.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 #include <net/netfilter/nf_tables_core.h>
  18
  19 struct nft_dynset {
  20         struct nft_set                  *set;
  21         struct nft_set_ext_tmpl         tmpl;
  22         enum nft_dynset_ops             op:8;
  23         enum nft_registers              sreg_key:8;
  24         enum nft_registers              sreg_data:8;
  25         bool                            invert;
  26         u64                             timeout;
  27         struct nft_expr                 *expr;
  28         struct nft_set_binding          binding;
  29 };
  30
  31 static void *nft_dynset_new(struct nft_set *set, const struct nft_expr *expr,
  32                             struct nft_regs *regs)
  33 {
  34         const struct nft_dynset *priv = nft_expr_priv(expr);
  35         struct nft_set_ext *ext;
  36         u64 timeout;
  37         void *elem;
  38
  39         if (set->size && !atomic_add_unless(&set->nelems, 1, set->size))
  40                 return NULL;
  41
  42         timeout = priv->timeout ? : set->timeout;
  43         elem = nft_set_elem_init(set, &priv->tmpl,
  44                                  &regs->data[priv->sreg_key],
  45                                  &regs->data[priv->sreg_data],
  46                                  timeout, GFP_ATOMIC);
  47         if (elem == NULL) {
  48                 if (set->size)
  49                         atomic_dec(&set->nelems);
  50                 return NULL;
  51         }
  52
  53         ext = nft_set_elem_ext(set, elem);
  54         if (priv->expr != NULL &&
  55             nft_expr_clone(nft_set_ext_expr(ext), priv->expr) < 0)
  56                 return NULL;
  57
  58         return elem;
  59 }
  60
  61 static void nft_dynset_eval(const struct nft_expr *expr,
  62                             struct nft_regs *regs,
  63                             const struct nft_pktinfo *pkt)
  64 {
  65         const struct nft_dynset *priv = nft_expr_priv(expr);
  66         struct nft_set *set = priv->set;
  67         const struct nft_set_ext *ext;
  68         const struct nft_expr *sexpr;
  69         u64 timeout;
  70
  71         if (set->ops->update(set, &regs->data[priv->sreg_key], nft_dynset_new,
  72                              expr, regs, &ext)) {
  73                 sexpr = NULL;
  74                 if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
  75                         sexpr = nft_set_ext_expr(ext);
  76
  77                 if (priv->op == NFT_DYNSET_OP_UPDATE &&
  78                     nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION)) {
  79                         timeout = priv->timeout ? : set->timeout;
  80                         *nft_set_ext_expiration(ext) = jiffies + timeout;
  81                 } else if (sexpr == NULL)
  82                         goto out;
  83
  84                 if (sexpr != NULL)
  85                         sexpr->ops->eval(sexpr, regs, pkt);
  86
  87                 if (priv->invert)
  88                         regs->verdict.code = NFT_BREAK;
  89                 return;
  90         }
  91 out:
  92         if (!priv->invert)
  93                 regs->verdict.code = NFT_BREAK;
  94 }
  95
  96 static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {
  97         [NFTA_DYNSET_SET_NAME]  = { .type = NLA_STRING },
  98         [NFTA_DYNSET_SET_ID]    = { .type = NLA_U32 },
  99         [NFTA_DYNSET_OP]        = { .type = NLA_U32 },
 100         [NFTA_DYNSET_SREG_KEY]  = { .type = NLA_U32 },
 101         [NFTA_DYNSET_SREG_DATA] = { .type = NLA_U32 },
 102         [NFTA_DYNSET_TIMEOUT]   = { .type = NLA_U64 },
 103         [NFTA_DYNSET_EXPR]      = { .type = NLA_NESTED },
 104         [NFTA_DYNSET_FLAGS]     = { .type = NLA_U32 },
 105 };
 106
 107 static int nft_dynset_init(const struct nft_ctx *ctx,
 108                            const struct nft_expr *expr,
 109                            const struct nlattr * const tb[])
 110 {
 111         struct nft_dynset *priv = nft_expr_priv(expr);
 112         u8 genmask = nft_genmask_next(ctx->net);
 113         struct nft_set *set;
 114         u64 timeout;
 115         int err;
 116
 117         if (tb[NFTA_DYNSET_SET_NAME] == NULL ||
 118             tb[NFTA_DYNSET_OP] == NULL ||
 119             tb[NFTA_DYNSET_SREG_KEY] == NULL)
 120                 return -EINVAL;
 121
 122         if (tb[NFTA_DYNSET_FLAGS]) {
 123                 u32 flags = ntohl(nla_get_be32(tb[NFTA_DYNSET_FLAGS]));
 124
 125                 if (flags & ~NFT_DYNSET_F_INV)
 126                         return -EINVAL;
 127                 if (flags & NFT_DYNSET_F_INV)
 128                         priv->invert = true;
 129         }
 130
 131         set = nf_tables_set_lookup(ctx->table, tb[NFTA_DYNSET_SET_NAME],
 132                                    genmask);
 133         if (IS_ERR(set)) {
 134                 if (tb[NFTA_DYNSET_SET_ID])
 135                         set = nf_tables_set_lookup_byid(ctx->net,
 136                                                         tb[NFTA_DYNSET_SET_ID],
 137                                                         genmask);
 138                 if (IS_ERR(set))
 139                         return PTR_ERR(set);
 140         }
 141
 142         if (set->flags & NFT_SET_CONSTANT)
 143                 return -EBUSY;
 144
 145         priv->op = ntohl(nla_get_be32(tb[NFTA_DYNSET_OP]));
 146         switch (priv->op) {
 147         case NFT_DYNSET_OP_ADD:
 148                 break;
 149         case NFT_DYNSET_OP_UPDATE:
 150                 if (!(set->flags & NFT_SET_TIMEOUT))
 151                         return -EOPNOTSUPP;
 152                 break;
 153         default:
 154                 return -EOPNOTSUPP;
 155         }
 156
 157         timeout = 0;
 158         if (tb[NFTA_DYNSET_TIMEOUT] != NULL) {
 159                 if (!(set->flags & NFT_SET_TIMEOUT))
 160                         return -EINVAL;
 161                 timeout = be64_to_cpu(nla_get_be64(tb[NFTA_DYNSET_TIMEOUT]));
 162         }
 163
 164         priv->sreg_key = nft_parse_register(tb[NFTA_DYNSET_SREG_KEY]);
 165         err = nft_validate_register_load(priv->sreg_key, set->klen);;
 166         if (err < 0)
 167                 return err;
 168
 169         if (tb[NFTA_DYNSET_SREG_DATA] != NULL) {
 170                 if (!(set->flags & NFT_SET_MAP))
 171                         return -EINVAL;
 172                 if (set->dtype == NFT_DATA_VERDICT)
 173                         return -EOPNOTSUPP;
 174
 175                 priv->sreg_data = nft_parse_register(tb[NFTA_DYNSET_SREG_DATA]);
 176                 err = nft_validate_register_load(priv->sreg_data, set->dlen);
 177                 if (err < 0)
 178                         return err;
 179         } else if (set->flags & NFT_SET_MAP)
 180                 return -EINVAL;
 181
 182         if (tb[NFTA_DYNSET_EXPR] != NULL) {
 183                 if (!(set->flags & NFT_SET_EVAL))
 184                         return -EINVAL;
 185                 if (!(set->flags & NFT_SET_ANONYMOUS))
 186                         return -EOPNOTSUPP;
 187
 188                 priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
 189                 if (IS_ERR(priv->expr))
 190                         return PTR_ERR(priv->expr);
 191
 192                 err = -EOPNOTSUPP;
 193                 if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
 194                         goto err1;
 195         } else if (set->flags & NFT_SET_EVAL)
 196                 return -EINVAL;
 197
 198         nft_set_ext_prepare(&priv->tmpl);
 199         nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 200         if (set->flags & NFT_SET_MAP)
 201                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
 202         if (priv->expr != NULL)
 203                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
 204                                        priv->expr->ops->size);
 205         if (set->flags & NFT_SET_TIMEOUT) {
 206                 if (timeout || set->timeout)
 207                         nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
 208         }
 209
 210         priv->timeout = timeout;
 211
 212         err = nf_tables_bind_set(ctx, set, &priv->binding);
 213         if (err < 0)
 214                 goto err1;
 215
 216         priv->set = set;
 217         return 0;
 218
 219 err1:
 220         if (priv->expr != NULL)
 221                 nft_expr_destroy(ctx, priv->expr);
 222         return err;
 223 }
 224
 225 static void nft_dynset_destroy(const struct nft_ctx *ctx,
 226                                const struct nft_expr *expr)
 227 {
 228         struct nft_dynset *priv = nft_expr_priv(expr);
 229
 230         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 231         if (priv->expr != NULL)
 232                 nft_expr_destroy(ctx, priv->expr);
 233 }
 234
 235 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 236 {
 237         const struct nft_dynset *priv = nft_expr_priv(expr);
 238         u32 flags = priv->invert ? NFT_DYNSET_F_INV : 0;
 239
 240         if (nft_dump_register(skb, NFTA_DYNSET_SREG_KEY, priv->sreg_key))
 241                 goto nla_put_failure;
 242         if (priv->set->flags & NFT_SET_MAP &&
 243             nft_dump_register(skb, NFTA_DYNSET_SREG_DATA, priv->sreg_data))
 244                 goto nla_put_failure;
 245         if (nla_put_be32(skb, NFTA_DYNSET_OP, htonl(priv->op)))
 246                 goto nla_put_failure;
 247         if (nla_put_string(skb, NFTA_DYNSET_SET_NAME, priv->set->name))
 248                 goto nla_put_failure;
 249         if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT, cpu_to_be64(priv->timeout),
 250                          NFTA_DYNSET_PAD))
 251                 goto nla_put_failure;
 252         if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
 253                 goto nla_put_failure;
 254         if (nla_put_be32(skb, NFTA_DYNSET_FLAGS, htonl(flags)))
 255                 goto nla_put_failure;
 256         return 0;
 257
 258 nla_put_failure:
 259         return -1;
 260 }
 261
 262 static struct nft_expr_type nft_dynset_type;
 263 static const struct nft_expr_ops nft_dynset_ops = {
 264         .type           = &nft_dynset_type,
 265         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dynset)),
 266         .eval           = nft_dynset_eval,
 267         .init           = nft_dynset_init,
 268         .destroy        = nft_dynset_destroy,
 269         .dump           = nft_dynset_dump,
 270 };
 271
 272 static struct nft_expr_type nft_dynset_type __read_mostly = {
 273         .name           = "dynset",
 274         .ops            = &nft_dynset_ops,
 275         .policy         = nft_dynset_policy,
 276         .maxattr        = NFTA_DYNSET_MAX,
 277         .owner          = THIS_MODULE,
 278 };
 279
 280 int __init nft_dynset_module_init(void)
 281 {
 282         return nft_register_expr(&nft_dynset_type);
 283 }
 284
 285 void nft_dynset_module_exit(void)
 286 {
 287         nft_unregister_expr(&nft_dynset_type);
 288 }