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