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 (!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) = get_jiffies_64() + timeout;
  85                 }
  86
  87                 if (sexpr != NULL)
  88                         sexpr->ops->eval(sexpr, regs, pkt);
  89
  90                 if (priv->invert)
  91                         regs->verdict.code = NFT_BREAK;
  92                 return;
  93         }
  94
  95         if (!priv->invert)
  96                 regs->verdict.code = NFT_BREAK;
  97 }
  98
  99 static const struct nla_policy nft_dynset_policy[NFTA_DYNSET_MAX + 1] = {
 100         [NFTA_DYNSET_SET_NAME]  = { .type = NLA_STRING,
 101                                     .len = NFT_SET_MAXNAMELEN - 1 },
 102         [NFTA_DYNSET_SET_ID]    = { .type = NLA_U32 },
 103         [NFTA_DYNSET_OP]        = { .type = NLA_U32 },
 104         [NFTA_DYNSET_SREG_KEY]  = { .type = NLA_U32 },
 105         [NFTA_DYNSET_SREG_DATA] = { .type = NLA_U32 },
 106         [NFTA_DYNSET_TIMEOUT]   = { .type = NLA_U64 },
 107         [NFTA_DYNSET_EXPR]      = { .type = NLA_NESTED },
 108         [NFTA_DYNSET_FLAGS]     = { .type = NLA_U32 },
 109 };
 110
 111 static int nft_dynset_init(const struct nft_ctx *ctx,
 112                            const struct nft_expr *expr,
 113                            const struct nlattr * const tb[])
 114 {
 115         struct nft_dynset *priv = nft_expr_priv(expr);
 116         u8 genmask = nft_genmask_next(ctx->net);
 117         struct nft_set *set;
 118         u64 timeout;
 119         int err;
 120
 121         if (tb[NFTA_DYNSET_SET_NAME] == NULL ||
 122             tb[NFTA_DYNSET_OP] == NULL ||
 123             tb[NFTA_DYNSET_SREG_KEY] == NULL)
 124                 return -EINVAL;
 125
 126         if (tb[NFTA_DYNSET_FLAGS]) {
 127                 u32 flags = ntohl(nla_get_be32(tb[NFTA_DYNSET_FLAGS]));
 128
 129                 if (flags & ~NFT_DYNSET_F_INV)
 130                         return -EINVAL;
 131                 if (flags & NFT_DYNSET_F_INV)
 132                         priv->invert = true;
 133         }
 134
 135         set = nft_set_lookup_global(ctx->net, ctx->table,
 136                                     tb[NFTA_DYNSET_SET_NAME],
 137                                     tb[NFTA_DYNSET_SET_ID], genmask);
 138         if (IS_ERR(set))
 139                 return PTR_ERR(set);
 140
 141         if (set->ops->update == NULL)
 142                 return -EOPNOTSUPP;
 143
 144         if (set->flags & NFT_SET_CONSTANT)
 145                 return -EBUSY;
 146
 147         priv->op = ntohl(nla_get_be32(tb[NFTA_DYNSET_OP]));
 148         switch (priv->op) {
 149         case NFT_DYNSET_OP_ADD:
 150                 break;
 151         case NFT_DYNSET_OP_UPDATE:
 152                 if (!(set->flags & NFT_SET_TIMEOUT))
 153                         return -EOPNOTSUPP;
 154                 break;
 155         default:
 156                 return -EOPNOTSUPP;
 157         }
 158
 159         timeout = 0;
 160         if (tb[NFTA_DYNSET_TIMEOUT] != NULL) {
 161                 if (!(set->flags & NFT_SET_TIMEOUT))
 162                         return -EINVAL;
 163                 timeout = msecs_to_jiffies(be64_to_cpu(nla_get_be64(
 164                                                 tb[NFTA_DYNSET_TIMEOUT])));
 165         }
 166
 167         priv->sreg_key = nft_parse_register(tb[NFTA_DYNSET_SREG_KEY]);
 168         err = nft_validate_register_load(priv->sreg_key, set->klen);
 169         if (err < 0)
 170                 return err;
 171
 172         if (tb[NFTA_DYNSET_SREG_DATA] != NULL) {
 173                 if (!(set->flags & NFT_SET_MAP))
 174                         return -EINVAL;
 175                 if (set->dtype == NFT_DATA_VERDICT)
 176                         return -EOPNOTSUPP;
 177
 178                 priv->sreg_data = nft_parse_register(tb[NFTA_DYNSET_SREG_DATA]);
 179                 err = nft_validate_register_load(priv->sreg_data, set->dlen);
 180                 if (err < 0)
 181                         return err;
 182         } else if (set->flags & NFT_SET_MAP)
 183                 return -EINVAL;
 184
 185         if (tb[NFTA_DYNSET_EXPR] != NULL) {
 186                 if (!(set->flags & NFT_SET_EVAL))
 187                         return -EINVAL;
 188                 if (!nft_set_is_anonymous(set))
 189                         return -EOPNOTSUPP;
 190
 191                 priv->expr = nft_expr_init(ctx, tb[NFTA_DYNSET_EXPR]);
 192                 if (IS_ERR(priv->expr))
 193                         return PTR_ERR(priv->expr);
 194
 195                 err = -EOPNOTSUPP;
 196                 if (!(priv->expr->ops->type->flags & NFT_EXPR_STATEFUL))
 197                         goto err1;
 198
 199                 if (priv->expr->ops->type->flags & NFT_EXPR_GC) {
 200                         if (set->flags & NFT_SET_TIMEOUT)
 201                                 goto err1;
 202                         if (!set->ops->gc_init)
 203                                 goto err1;
 204                         set->ops->gc_init(set);
 205                 }
 206         }
 207
 208         nft_set_ext_prepare(&priv->tmpl);
 209         nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_KEY, set->klen);
 210         if (set->flags & NFT_SET_MAP)
 211                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_DATA, set->dlen);
 212         if (priv->expr != NULL)
 213                 nft_set_ext_add_length(&priv->tmpl, NFT_SET_EXT_EXPR,
 214                                        priv->expr->ops->size);
 215         if (set->flags & NFT_SET_TIMEOUT) {
 216                 if (timeout || set->timeout)
 217                         nft_set_ext_add(&priv->tmpl, NFT_SET_EXT_EXPIRATION);
 218         }
 219
 220         priv->timeout = timeout;
 221
 222         err = nf_tables_bind_set(ctx, set, &priv->binding);
 223         if (err < 0)
 224                 goto err1;
 225
 226         if (set->size == 0)
 227                 set->size = 0xffff;
 228
 229         priv->set = set;
 230         return 0;
 231
 232 err1:
 233         if (priv->expr != NULL)
 234                 nft_expr_destroy(ctx, priv->expr);
 235         return err;
 236 }
 237
 238 static void nft_dynset_destroy(const struct nft_ctx *ctx,
 239                                const struct nft_expr *expr)
 240 {
 241         struct nft_dynset *priv = nft_expr_priv(expr);
 242
 243         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 244         if (priv->expr != NULL)
 245                 nft_expr_destroy(ctx, priv->expr);
 246 }
 247
 248 static int nft_dynset_dump(struct sk_buff *skb, const struct nft_expr *expr)
 249 {
 250         const struct nft_dynset *priv = nft_expr_priv(expr);
 251         u32 flags = priv->invert ? NFT_DYNSET_F_INV : 0;
 252
 253         if (nft_dump_register(skb, NFTA_DYNSET_SREG_KEY, priv->sreg_key))
 254                 goto nla_put_failure;
 255         if (priv->set->flags & NFT_SET_MAP &&
 256             nft_dump_register(skb, NFTA_DYNSET_SREG_DATA, priv->sreg_data))
 257                 goto nla_put_failure;
 258         if (nla_put_be32(skb, NFTA_DYNSET_OP, htonl(priv->op)))
 259                 goto nla_put_failure;
 260         if (nla_put_string(skb, NFTA_DYNSET_SET_NAME, priv->set->name))
 261                 goto nla_put_failure;
 262         if (nla_put_be64(skb, NFTA_DYNSET_TIMEOUT,
 263                          cpu_to_be64(jiffies_to_msecs(priv->timeout)),
 264                          NFTA_DYNSET_PAD))
 265                 goto nla_put_failure;
 266         if (priv->expr && nft_expr_dump(skb, NFTA_DYNSET_EXPR, priv->expr))
 267                 goto nla_put_failure;
 268         if (nla_put_be32(skb, NFTA_DYNSET_FLAGS, htonl(flags)))
 269                 goto nla_put_failure;
 270         return 0;
 271
 272 nla_put_failure:
 273         return -1;
 274 }
 275
 276 static const struct nft_expr_ops nft_dynset_ops = {
 277         .type           = &nft_dynset_type,
 278         .size           = NFT_EXPR_SIZE(sizeof(struct nft_dynset)),
 279         .eval           = nft_dynset_eval,
 280         .init           = nft_dynset_init,
 281         .destroy        = nft_dynset_destroy,
 282         .dump           = nft_dynset_dump,
 283 };
 284
 285 struct nft_expr_type nft_dynset_type __read_mostly = {
 286         .name           = "dynset",
 287         .ops            = &nft_dynset_ops,
 288         .policy         = nft_dynset_policy,
 289         .maxattr        = NFTA_DYNSET_MAX,
 290         .owner          = THIS_MODULE,
 291 };