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) < 0)
  55                 return NULL;
  56
  57         return elem;
  58 }
  59
  60 static void nft_dynset_eval(const struct nft_expr *expr,
  61                             struct nft_regs *regs,
  62                             const struct nft_pktinfo *pkt)
  63 {
  64         const struct nft_dynset *priv = nft_expr_priv(expr);
  65         struct nft_set *set = priv->set;
  66         const struct nft_set_ext *ext;
  67         const struct nft_expr *sexpr;
  68         u64 timeout;
  69
  70         if (set->ops->update(set, &regs->data[priv->sreg_key], nft_dynset_new,
  71                              expr, regs, &ext)) {
  72                 sexpr = NULL;
  73                 if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
  74                         sexpr = nft_set_ext_expr(ext);
  75
  76                 if (priv->op == NFT_DYNSET_OP_UPDATE &&
  77                     nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION)) {
  78                         timeout = priv->timeout ? : set->timeout;
  79                         *nft_set_ext_expiration(ext) = jiffies + timeout;
  80                 } else if (sexpr == NULL)
  81                         goto out;
  82
  83                 if (sexpr != NULL)
  84                         sexpr->ops->eval(sexpr, regs, pkt);
  85                 return;
  86         }
  87 out:
  88         regs->verdict.code = NFT_BREAK;
  89 }
  90
  91 static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {
  92         [NFTA_DYNSET_SET_NAME]  = { .type = NLA_STRING },
  93         [NFTA_DYNSET_SET_ID]    = { .type = NLA_U32 },
  94         [NFTA_DYNSET_OP]        = { .type = NLA_U32 },
  95         [NFTA_DYNSET_SREG_KEY]  = { .type = NLA_U32 },
  96         [NFTA_DYNSET_SREG_DATA] = { .type = NLA_U32 },
  97         [NFTA_DYNSET_TIMEOUT]   = { .type = NLA_U64 },
  98         [NFTA_DYNSET_EXPR]      = { .type = NLA_NESTED },
  99 };
 100
 101 static int nft_dynset_init(const struct nft_ctx *ctx,
 102                            const struct nft_expr *expr,
 103                            const struct nlattr * const tb[])
 104 {
 105         struct nft_dynset *priv = nft_expr_priv(expr);
 106         struct nft_set *set;
 107         u64 timeout;
 108         int err;
 109
 110         if (tb[NFTA_DYNSET_SET_NAME] == NULL ||
 111             tb[NFTA_DYNSET_OP] == NULL ||
 112             tb[NFTA_DYNSET_SREG_KEY] == NULL)
 113                 return -EINVAL;
 114
 115         set = nf_tables_set_lookup(ctx->table, tb[NFTA_DYNSET_SET_NAME]);
 116         if (IS_ERR(set)) {
 117                 if (tb[NFTA_DYNSET_SET_ID])
 118                         set = nf_tables_set_lookup_byid(ctx->net,
 119                                                         tb[NFTA_DYNSET_SET_ID]);
 120                 if (IS_ERR(set))
 121                         return PTR_ERR(set);
 122         }
 123
 124         if (set->flags & NFT_SET_CONSTANT)
 125                 return -EBUSY;
 126
 127         priv->op = ntohl(nla_get_be32(tb[NFTA_DYNSET_OP]));
 128         switch (priv->op) {
 129         case NFT_DYNSET_OP_ADD:
 130                 break;
 131         case NFT_DYNSET_OP_UPDATE:
 132                 if (!(set->flags & NFT_SET_TIMEOUT))
 133                         return -EOPNOTSUPP;
 134                 break;
 135         default:
 136                 return -EOPNOTSUPP;
 137         }
 138
 139         timeout = 0;
 140         if (tb[NFTA_DYNSET_TIMEOUT] != NULL) {
 141                 if (!(set->flags & NFT_SET_TIMEOUT))
 142                         return -EINVAL;
 143                 timeout = be64_to_cpu(nla_get_be64(tb[NFTA_DYNSET_TIMEOUT]));
 144         }
 145
 146         priv->sreg_key = nft_parse_register(tb[NFTA_DYNSET_SREG_KEY]);
 147         err = nft_validate_register_load(priv->sreg_key, set->klen);;
 148         if (err < 0)
 149                 return err;
 150
 151         if (tb[NFTA_DYNSET_SREG_DATA] != NULL) {
 152                 if (!(set->flags & NFT_SET_MAP))
 153                         return -EINVAL;
 154                 if (set->dtype == NFT_DATA_VERDICT)
 155                         return -EOPNOTSUPP;
 156
 157                 priv->sreg_data = nft_parse_register(tb[NFTA_DYNSET_SREG_DATA]);
 158                 err = nft_validate_register_load(priv->sreg_data, set->dlen);
 159                 if (err < 0)
 160                         return err;
 161         } else if (set->flags & NFT_SET_MAP)
 162                 return -EINVAL;
 163
 164         if (tb[NFTA_DYNSET_EXPR] != NULL) {
 165                 if (!(set->flags & NFT_SET_EVAL))
 166                         return -EINVAL;
 167                 if (!(set->flags & NFT_SET_ANONYMOUS))
 168                         return -EOPNOTSUPP;
 169
 170                 priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
 171                 if (IS_ERR(priv->expr))
 172                         return PTR_ERR(priv->expr);
 173
 174                 err = -EOPNOTSUPP;
 175                 if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
 176                         goto err1;
 177         } else if (set->flags & NFT_SET_EVAL)
 178                 return -EINVAL;
 179
 180         nft_set_ext_prepare(&priv->tmpl);
 181         nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 182         if (set->flags & NFT_SET_MAP)
 183                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
 184         if (priv->expr != NULL)
 185                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
 186                                        priv->expr->ops->size);
 187         if (set->flags & NFT_SET_TIMEOUT) {
 188                 if (timeout || set->timeout)
 189                         nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
 190         }
 191
 192         priv->timeout = timeout;
 193
 194         err = nf_tables_bind_set(ctx, set, &priv->binding);
 195         if (err < 0)
 196                 goto err1;
 197
 198         priv->set = set;
 199         return 0;
 200
 201 err1:
 202         if (priv->expr != NULL)
 203                 nft_expr_destroy(ctx, priv->expr);
 204         return err;
 205 }
 206
 207 static void nft_dynset_destroy(const struct nft_ctx *ctx,
 208                                const struct nft_expr *expr)
 209 {
 210         struct nft_dynset *priv = nft_expr_priv(expr);
 211
 212         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 213         if (priv->expr != NULL)
 214                 nft_expr_destroy(ctx, priv->expr);
 215 }
 216
 217 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 218 {
 219         const struct nft_dynset *priv = nft_expr_priv(expr);
 220
 221         if (nft_dump_register(skb, NFTA_DYNSET_SREG_KEY, priv->sreg_key))
 222                 goto nla_put_failure;
 223         if (priv->set->flags & NFT_SET_MAP &&
 224             nft_dump_register(skb, NFTA_DYNSET_SREG_DATA, priv->sreg_data))
 225                 goto nla_put_failure;
 226         if (nla_put_be32(skb, NFTA_DYNSET_OP, htonl(priv->op)))
 227                 goto nla_put_failure;
 228         if (nla_put_string(skb, NFTA_DYNSET_SET_NAME, priv->set->name))
 229                 goto nla_put_failure;
 230         if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT, cpu_to_be64(priv->timeout),
 231                          NFTA_DYNSET_PAD))
 232                 goto nla_put_failure;
 233         if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
 234                 goto nla_put_failure;
 235         return 0;
 236
 237 nla_put_failure:
 238         return -1;
 239 }
 240
 241 static struct nft_expr_type nft_dynset_type;
 242 static const struct nft_expr_ops nft_dynset_ops = {
 243         .type           = &nft_dynset_type,
 244         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dynset)),
 245         .eval           = nft_dynset_eval,
 246         .init           = nft_dynset_init,
 247         .destroy        = nft_dynset_destroy,
 248         .dump           = nft_dynset_dump,
 249 };
 250
 251 static struct nft_expr_type nft_dynset_type __read_mostly = {
 252         .name           = "dynset",
 253         .ops            = &nft_dynset_ops,
 254         .policy         = nft_dynset_policy,
 255         .maxattr        = NFTA_DYNSET_MAX,
 256         .owner          = THIS_MODULE,
 257 };
 258
 259 int __init nft_dynset_module_init(void)
 260 {
 261         return nft_register_expr(&nft_dynset_type);
 262 }
 263
 264 void nft_dynset_module_exit(void)
 265 {
 266         nft_unregister_expr(&nft_dynset_type);
 267 }