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         u8 genmask = nft_genmask_next(ctx->net);
 107         struct nft_set *set;
 108         u64 timeout;
 109         int err;
 110
 111         if (tb[NFTA_DYNSET_SET_NAME] == NULL ||
 112             tb[NFTA_DYNSET_OP] == NULL ||
 113             tb[NFTA_DYNSET_SREG_KEY] == NULL)
 114                 return -EINVAL;
 115
 116         set = nf_tables_set_lookup(ctx->table, tb[NFTA_DYNSET_SET_NAME],
 117                                    genmask);
 118         if (IS_ERR(set)) {
 119                 if (tb[NFTA_DYNSET_SET_ID])
 120                         set = nf_tables_set_lookup_byid(ctx->net,
 121                                                         tb[NFTA_DYNSET_SET_ID],
 122                                                         genmask);
 123                 if (IS_ERR(set))
 124                         return PTR_ERR(set);
 125         }
 126
 127         if (set->flags & NFT_SET_CONSTANT)
 128                 return -EBUSY;
 129
 130         priv->op = ntohl(nla_get_be32(tb[NFTA_DYNSET_OP]));
 131         switch (priv->op) {
 132         case NFT_DYNSET_OP_ADD:
 133                 break;
 134         case NFT_DYNSET_OP_UPDATE:
 135                 if (!(set->flags & NFT_SET_TIMEOUT))
 136                         return -EOPNOTSUPP;
 137                 break;
 138         default:
 139                 return -EOPNOTSUPP;
 140         }
 141
 142         timeout = 0;
 143         if (tb[NFTA_DYNSET_TIMEOUT] != NULL) {
 144                 if (!(set->flags & NFT_SET_TIMEOUT))
 145                         return -EINVAL;
 146                 timeout = be64_to_cpu(nla_get_be64(tb[NFTA_DYNSET_TIMEOUT]));
 147         }
 148
 149         priv->sreg_key = nft_parse_register(tb[NFTA_DYNSET_SREG_KEY]);
 150         err = nft_validate_register_load(priv->sreg_key, set->klen);;
 151         if (err < 0)
 152                 return err;
 153
 154         if (tb[NFTA_DYNSET_SREG_DATA] != NULL) {
 155                 if (!(set->flags & NFT_SET_MAP))
 156                         return -EINVAL;
 157                 if (set->dtype == NFT_DATA_VERDICT)
 158                         return -EOPNOTSUPP;
 159
 160                 priv->sreg_data = nft_parse_register(tb[NFTA_DYNSET_SREG_DATA]);
 161                 err = nft_validate_register_load(priv->sreg_data, set->dlen);
 162                 if (err < 0)
 163                         return err;
 164         } else if (set->flags & NFT_SET_MAP)
 165                 return -EINVAL;
 166
 167         if (tb[NFTA_DYNSET_EXPR] != NULL) {
 168                 if (!(set->flags & NFT_SET_EVAL))
 169                         return -EINVAL;
 170                 if (!(set->flags & NFT_SET_ANONYMOUS))
 171                         return -EOPNOTSUPP;
 172
 173                 priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
 174                 if (IS_ERR(priv->expr))
 175                         return PTR_ERR(priv->expr);
 176
 177                 err = -EOPNOTSUPP;
 178                 if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
 179                         goto err1;
 180         } else if (set->flags & NFT_SET_EVAL)
 181                 return -EINVAL;
 182
 183         nft_set_ext_prepare(&priv->tmpl);
 184         nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 185         if (set->flags & NFT_SET_MAP)
 186                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
 187         if (priv->expr != NULL)
 188                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
 189                                        priv->expr->ops->size);
 190         if (set->flags & NFT_SET_TIMEOUT) {
 191                 if (timeout || set->timeout)
 192                         nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
 193         }
 194
 195         priv->timeout = timeout;
 196
 197         err = nf_tables_bind_set(ctx, set, &priv->binding);
 198         if (err < 0)
 199                 goto err1;
 200
 201         priv->set = set;
 202         return 0;
 203
 204 err1:
 205         if (priv->expr != NULL)
 206                 nft_expr_destroy(ctx, priv->expr);
 207         return err;
 208 }
 209
 210 static void nft_dynset_destroy(const struct nft_ctx *ctx,
 211                                const struct nft_expr *expr)
 212 {
 213         struct nft_dynset *priv = nft_expr_priv(expr);
 214
 215         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 216         if (priv->expr != NULL)
 217                 nft_expr_destroy(ctx, priv->expr);
 218 }
 219
 220 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 221 {
 222         const struct nft_dynset *priv = nft_expr_priv(expr);
 223
 224         if (nft_dump_register(skb, NFTA_DYNSET_SREG_KEY, priv->sreg_key))
 225                 goto nla_put_failure;
 226         if (priv->set->flags & NFT_SET_MAP &&
 227             nft_dump_register(skb, NFTA_DYNSET_SREG_DATA, priv->sreg_data))
 228                 goto nla_put_failure;
 229         if (nla_put_be32(skb, NFTA_DYNSET_OP, htonl(priv->op)))
 230                 goto nla_put_failure;
 231         if (nla_put_string(skb, NFTA_DYNSET_SET_NAME, priv->set->name))
 232                 goto nla_put_failure;
 233         if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT, cpu_to_be64(priv->timeout),
 234                          NFTA_DYNSET_PAD))
 235                 goto nla_put_failure;
 236         if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
 237                 goto nla_put_failure;
 238         return 0;
 239
 240 nla_put_failure:
 241         return -1;
 242 }
 243
 244 static struct nft_expr_type nft_dynset_type;
 245 static const struct nft_expr_ops nft_dynset_ops = {
 246         .type           = &nft_dynset_type,
 247         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dynset)),
 248         .eval           = nft_dynset_eval,
 249         .init           = nft_dynset_init,
 250         .destroy        = nft_dynset_destroy,
 251         .dump           = nft_dynset_dump,
 252 };
 253
 254 static struct nft_expr_type nft_dynset_type __read_mostly = {
 255         .name           = "dynset",
 256         .ops            = &nft_dynset_ops,
 257         .policy         = nft_dynset_policy,
 258         .maxattr        = NFTA_DYNSET_MAX,
 259         .owner          = THIS_MODULE,
 260 };
 261
 262 int __init nft_dynset_module_init(void)
 263 {
 264         return nft_register_expr(&nft_dynset_type);
 265 }
 266
 267 void nft_dynset_module_exit(void)
 268 {
 269         nft_unregister_expr(&nft_dynset_type);
 270 }