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                 goto err1;
  49
  50         ext = nft_set_elem_ext(set, elem);
  51         if (priv->expr != NULL &&
  52             nft_expr_clone(nft_set_ext_expr(ext), priv->expr) < 0)
  53                 goto err2;
  54
  55         return elem;
  56
  57 err2:
  58         nft_set_elem_destroy(set, elem, false);
  59 err1:
  60         if (set->size)
  61                 atomic_dec(&set->nelems);
  62         return NULL;
  63 }
  64
  65 static void nft_dynset_eval(const struct nft_expr *expr,
  66                             struct nft_regs *regs,
  67                             const struct nft_pktinfo *pkt)
  68 {
  69         const struct nft_dynset *priv = nft_expr_priv(expr);
  70         struct nft_set *set = priv->set;
  71         const struct nft_set_ext *ext;
  72         const struct nft_expr *sexpr;
  73         u64 timeout;
  74
  75         if (set->ops->update(set, &regs->data[priv->sreg_key], nft_dynset_new,
  76                              expr, regs, &ext)) {
  77                 sexpr = NULL;
  78                 if (nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
  79                         sexpr = nft_set_ext_expr(ext);
  80
  81                 if (priv->op == NFT_DYNSET_OP_UPDATE &&
  82                     nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION)) {
  83                         timeout = priv->timeout ? : set->timeout;
  84                         *nft_set_ext_expiration(ext) = jiffies + timeout;
  85                 } else if (sexpr == NULL)
  86                         goto out;
  87
  88                 if (sexpr != NULL)
  89                         sexpr->ops->eval(sexpr, regs, pkt);
  90
  91                 if (priv->invert)
  92                         regs->verdict.code = NFT_BREAK;
  93                 return;
  94         }
  95 out:
  96         if (!priv->invert)
  97                 regs->verdict.code = NFT_BREAK;
  98 }
  99
 100 static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {
 101         [NFTA_DYNSET_SET_NAME]  = { .type = NLA_STRING,
 102                                     .len = NFT_SET_MAXNAMELEN - 1 },
 103         [NFTA_DYNSET_SET_ID]    = { .type = NLA_U32 },
 104         [NFTA_DYNSET_OP]        = { .type = NLA_U32 },
 105         [NFTA_DYNSET_SREG_KEY]  = { .type = NLA_U32 },
 106         [NFTA_DYNSET_SREG_DATA] = { .type = NLA_U32 },
 107         [NFTA_DYNSET_TIMEOUT]   = { .type = NLA_U64 },
 108         [NFTA_DYNSET_EXPR]      = { .type = NLA_NESTED },
 109         [NFTA_DYNSET_FLAGS]     = { .type = NLA_U32 },
 110 };
 111
 112 static int nft_dynset_init(const struct nft_ctx *ctx,
 113                            const struct nft_expr *expr,
 114                            const struct nlattr * const tb[])
 115 {
 116         struct nft_dynset *priv = nft_expr_priv(expr);
 117         u8 genmask = nft_genmask_next(ctx->net);
 118         struct nft_set *set;
 119         u64 timeout;
 120         int err;
 121
 122         if (tb[NFTA_DYNSET_SET_NAME] == NULL ||
 123             tb[NFTA_DYNSET_OP] == NULL ||
 124             tb[NFTA_DYNSET_SREG_KEY] == NULL)
 125                 return -EINVAL;
 126
 127         if (tb[NFTA_DYNSET_FLAGS]) {
 128                 u32 flags = ntohl(nla_get_be32(tb[NFTA_DYNSET_FLAGS]));
 129
 130                 if (flags & ~NFT_DYNSET_F_INV)
 131                         return -EINVAL;
 132                 if (flags & NFT_DYNSET_F_INV)
 133                         priv->invert = true;
 134         }
 135
 136         set = nf_tables_set_lookup(ctx->table, tb[NFTA_DYNSET_SET_NAME],
 137                                    genmask);
 138         if (IS_ERR(set)) {
 139                 if (tb[NFTA_DYNSET_SET_ID])
 140                         set = nf_tables_set_lookup_byid(ctx->net,
 141                                                         tb[NFTA_DYNSET_SET_ID],
 142                                                         genmask);
 143                 if (IS_ERR(set))
 144                         return PTR_ERR(set);
 145         }
 146
 147         if (set->ops->update == NULL)
 148                 return -EOPNOTSUPP;
 149
 150         if (set->flags & NFT_SET_CONSTANT)
 151                 return -EBUSY;
 152
 153         priv->op = ntohl(nla_get_be32(tb[NFTA_DYNSET_OP]));
 154         switch (priv->op) {
 155         case NFT_DYNSET_OP_ADD:
 156                 break;
 157         case NFT_DYNSET_OP_UPDATE:
 158                 if (!(set->flags & NFT_SET_TIMEOUT))
 159                         return -EOPNOTSUPP;
 160                 break;
 161         default:
 162                 return -EOPNOTSUPP;
 163         }
 164
 165         timeout = 0;
 166         if (tb[NFTA_DYNSET_TIMEOUT] != NULL) {
 167                 if (!(set->flags & NFT_SET_TIMEOUT))
 168                         return -EINVAL;
 169                 timeout = msecs_to_jiffies(be64_to_cpu(nla_get_be64(
 170                                                 tb[NFTA_DYNSET_TIMEOUT])));
 171         }
 172
 173         priv->sreg_key = nft_parse_register(tb[NFTA_DYNSET_SREG_KEY]);
 174         err = nft_validate_register_load(priv->sreg_key, set->klen);;
 175         if (err < 0)
 176                 return err;
 177
 178         if (tb[NFTA_DYNSET_SREG_DATA] != NULL) {
 179                 if (!(set->flags & NFT_SET_MAP))
 180                         return -EINVAL;
 181                 if (set->dtype == NFT_DATA_VERDICT)
 182                         return -EOPNOTSUPP;
 183
 184                 priv->sreg_data = nft_parse_register(tb[NFTA_DYNSET_SREG_DATA]);
 185                 err = nft_validate_register_load(priv->sreg_data, set->dlen);
 186                 if (err < 0)
 187                         return err;
 188         } else if (set->flags & NFT_SET_MAP)
 189                 return -EINVAL;
 190
 191         if (tb[NFTA_DYNSET_EXPR] != NULL) {
 192                 if (!(set->flags & NFT_SET_EVAL))
 193                         return -EINVAL;
 194                 if (!(set->flags & NFT_SET_ANONYMOUS))
 195                         return -EOPNOTSUPP;
 196
 197                 priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
 198                 if (IS_ERR(priv->expr))
 199                         return PTR_ERR(priv->expr);
 200
 201                 err = -EOPNOTSUPP;
 202                 if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
 203                         goto err1;
 204         } else if (set->flags & NFT_SET_EVAL)
 205                 return -EINVAL;
 206
 207         nft_set_ext_prepare(&priv->tmpl);
 208         nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 209         if (set->flags & NFT_SET_MAP)
 210                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
 211         if (priv->expr != NULL)
 212                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
 213                                        priv->expr->ops->size);
 214         if (set->flags & NFT_SET_TIMEOUT) {
 215                 if (timeout || set->timeout)
 216                         nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
 217         }
 218
 219         priv->timeout = timeout;
 220
 221         err = nf_tables_bind_set(ctx, set, &priv->binding);
 222         if (err < 0)
 223                 goto err1;
 224
 225         priv->set = set;
 226         return 0;
 227
 228 err1:
 229         if (priv->expr != NULL)
 230                 nft_expr_destroy(ctx, priv->expr);
 231         return err;
 232 }
 233
 234 static void nft_dynset_destroy(const struct nft_ctx *ctx,
 235                                const struct nft_expr *expr)
 236 {
 237         struct nft_dynset *priv = nft_expr_priv(expr);
 238
 239         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 240         if (priv->expr != NULL)
 241                 nft_expr_destroy(ctx, priv->expr);
 242 }
 243
 244 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 245 {
 246         const struct nft_dynset *priv = nft_expr_priv(expr);
 247         u32 flags = priv->invert ? NFT_DYNSET_F_INV : 0;
 248
 249         if (nft_dump_register(skb, NFTA_DYNSET_SREG_KEY, priv->sreg_key))
 250                 goto nla_put_failure;
 251         if (priv->set->flags & NFT_SET_MAP &&
 252             nft_dump_register(skb, NFTA_DYNSET_SREG_DATA, priv->sreg_data))
 253                 goto nla_put_failure;
 254         if (nla_put_be32(skb, NFTA_DYNSET_OP, htonl(priv->op)))
 255                 goto nla_put_failure;
 256         if (nla_put_string(skb, NFTA_DYNSET_SET_NAME, priv->set->name))
 257                 goto nla_put_failure;
 258         if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT,
 259                          cpu_to_be64(jiffies_to_msecs(priv->timeout)),
 260                          NFTA_DYNSET_PAD))
 261                 goto nla_put_failure;
 262         if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
 263                 goto nla_put_failure;
 264         if (nla_put_be32(skb, NFTA_DYNSET_FLAGS, htonl(flags)))
 265                 goto nla_put_failure;
 266         return 0;
 267
 268 nla_put_failure:
 269         return -1;
 270 }
 271
 272 static const struct nft_expr_ops nft_dynset_ops = {
 273         .type           = &nft_dynset_type,
 274         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dynset)),
 275         .eval           = nft_dynset_eval,
 276         .init           = nft_dynset_init,
 277         .destroy        = nft_dynset_destroy,
 278         .dump           = nft_dynset_dump,
 279 };
 280
 281 struct nft_expr_type nft_dynset_type __read_mostly = {
 282         .name           = "dynset",
 283         .ops            = &nft_dynset_ops,
 284         .policy         = nft_dynset_policy,
 285         .maxattr        = NFTA_DYNSET_MAX,
 286         .owner          = THIS_MODULE,
 287 };