net/netfilter/nft_objref.c

   1 /*
   2  * Copyright (c) 2012-2016 Pablo Neira Ayuso <pablo@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/netlink.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/netfilter/nf_tables.h>
  15 #include <net/netfilter/nf_tables.h>
  16
  17 #define nft_objref_priv(expr)   *((struct nft_object **)nft_expr_priv(expr))
  18
  19 static void nft_objref_eval(const struct nft_expr *expr,
  20                             struct nft_regs *regs,
  21                             const struct nft_pktinfo *pkt)
  22 {
  23         struct nft_object *obj = nft_objref_priv(expr);
  24
  25         obj->type->eval(obj, regs, pkt);
  26 }
  27
  28 static int nft_objref_init(const struct nft_ctx *ctx,
  29                            const struct nft_expr *expr,
  30                            const struct nlattr * const tb[])
  31 {
  32         struct nft_object *obj = nft_objref_priv(expr);
  33         u8 genmask = nft_genmask_next(ctx->net);
  34         u32 objtype;
  35
  36         if (!tb[NFTA_OBJREF_IMM_NAME] ||
  37             !tb[NFTA_OBJREF_IMM_TYPE])
  38                 return -EINVAL;
  39
  40         objtype = ntohl(nla_get_be32(tb[NFTA_OBJREF_IMM_TYPE]));
  41         obj = nf_tables_obj_lookup(ctx->table, tb[NFTA_OBJREF_IMM_NAME], objtype,
  42                                    genmask);
  43         if (IS_ERR(obj))
  44                 return -ENOENT;
  45
  46         nft_objref_priv(expr) = obj;
  47         obj->use++;
  48
  49         return 0;
  50 }
  51
  52 static int nft_objref_dump(struct sk_buff *skb, const struct nft_expr *expr)
  53 {
  54         const struct nft_object *obj = nft_objref_priv(expr);
  55
  56         if (nla_put_string(skb, NFTA_OBJREF_IMM_NAME, obj->name) ||
  57             nla_put_be32(skb, NFTA_OBJREF_IMM_TYPE, htonl(obj->type->type)))
  58                 goto nla_put_failure;
  59
  60         return 0;
  61
  62 nla_put_failure:
  63         return -1;
  64 }
  65
  66 static void nft_objref_destroy(const struct nft_ctx *ctx,
  67                                const struct nft_expr *expr)
  68 {
  69         struct nft_object *obj = nft_objref_priv(expr);
  70
  71         obj->use--;
  72 }
  73
  74 static struct nft_expr_type nft_objref_type;
  75 static const struct nft_expr_ops nft_objref_ops = {
  76         .type           = &nft_objref_type,
  77         .size           = NFT_EXPR_SIZE(sizeof(struct nft_object *)),
  78         .eval           = nft_objref_eval,
  79         .init           = nft_objref_init,
  80         .destroy        = nft_objref_destroy,
  81         .dump           = nft_objref_dump,
  82 };
  83
  84 struct nft_objref_map {
  85         struct nft_set          *set;
  86         enum nft_registers      sreg:8;
  87         struct nft_set_binding  binding;
  88 };
  89
  90 static void nft_objref_map_eval(const struct nft_expr *expr,
  91                                 struct nft_regs *regs,
  92                                 const struct nft_pktinfo *pkt)
  93 {
  94         struct nft_objref_map *priv = nft_expr_priv(expr);
  95         const struct nft_set *set = priv->set;
  96         const struct nft_set_ext *ext;
  97         struct nft_object *obj;
  98         bool found;
  99
 100         found = set->ops->lookup(nft_net(pkt), set, &regs->data[priv->sreg],
 101                                  &ext);
 102         if (!found) {
 103                 regs->verdict.code = NFT_BREAK;
 104                 return;
 105         }
 106         obj = *nft_set_ext_obj(ext);
 107         obj->type->eval(obj, regs, pkt);
 108 }
 109
 110 static int nft_objref_map_init(const struct nft_ctx *ctx,
 111                                const struct nft_expr *expr,
 112                                const struct nlattr * const tb[])
 113 {
 114         struct nft_objref_map *priv = nft_expr_priv(expr);
 115         u8 genmask = nft_genmask_next(ctx->net);
 116         struct nft_set *set;
 117         int err;
 118
 119         set = nf_tables_set_lookup(ctx->table, tb[NFTA_OBJREF_SET_NAME], genmask);
 120         if (IS_ERR(set)) {
 121                 if (tb[NFTA_OBJREF_SET_ID]) {
 122                         set = nf_tables_set_lookup_byid(ctx->net,
 123                                                         tb[NFTA_OBJREF_SET_ID],
 124                                                         genmask);
 125                 }
 126                 if (IS_ERR(set))
 127                         return PTR_ERR(set);
 128         }
 129
 130         if (!(set->flags & NFT_SET_OBJECT))
 131                 return -EINVAL;
 132
 133         priv->sreg = nft_parse_register(tb[NFTA_OBJREF_SET_SREG]);
 134         err = nft_validate_register_load(priv->sreg, set->klen);
 135         if (err < 0)
 136                 return err;
 137
 138         priv->binding.flags = set->flags & NFT_SET_OBJECT;
 139
 140         err = nf_tables_bind_set(ctx, set, &priv->binding);
 141         if (err < 0)
 142                 return err;
 143
 144         priv->set = set;
 145         return 0;
 146 }
 147
 148 static int nft_objref_map_dump(struct sk_buff *skb, const struct nft_expr *expr)
 149 {
 150         const struct nft_objref_map *priv = nft_expr_priv(expr);
 151
 152         if (nft_dump_register(skb, NFTA_OBJREF_SET_SREG, priv->sreg) ||
 153             nla_put_string(skb, NFTA_OBJREF_SET_NAME, priv->set->name))
 154                 goto nla_put_failure;
 155
 156         return 0;
 157
 158 nla_put_failure:
 159         return -1;
 160 }
 161
 162 static void nft_objref_map_destroy(const struct nft_ctx *ctx,
 163                                    const struct nft_expr *expr)
 164 {
 165         struct nft_objref_map *priv = nft_expr_priv(expr);
 166
 167         nf_tables_unbind_set(ctx, priv->set, &priv->binding);
 168 }
 169
 170 static struct nft_expr_type nft_objref_type;
 171 static const struct nft_expr_ops nft_objref_map_ops = {
 172         .type           = &nft_objref_type,
 173         .size           = NFT_EXPR_SIZE(sizeof(struct nft_objref_map)),
 174         .eval           = nft_objref_map_eval,
 175         .init           = nft_objref_map_init,
 176         .destroy        = nft_objref_map_destroy,
 177         .dump           = nft_objref_map_dump,
 178 };
 179
 180 static const struct nft_expr_ops *
 181 nft_objref_select_ops(const struct nft_ctx *ctx,
 182                       const struct nlattr * const tb[])
 183 {
 184         if (tb[NFTA_OBJREF_SET_SREG] &&
 185             (tb[NFTA_OBJREF_SET_NAME] ||
 186              tb[NFTA_OBJREF_SET_ID]))
 187                 return &nft_objref_map_ops;
 188         else if (tb[NFTA_OBJREF_IMM_NAME] &&
 189                  tb[NFTA_OBJREF_IMM_TYPE])
 190                 return &nft_objref_ops;
 191
 192         return ERR_PTR(-EOPNOTSUPP);
 193 }
 194
 195 static const struct nla_policy nft_objref_policy[NFTA_OBJREF_MAX + 1] = {
 196         [NFTA_OBJREF_IMM_NAME]  = { .type = NLA_STRING,
 197                                     .len = NFT_OBJ_MAXNAMELEN - 1 },
 198         [NFTA_OBJREF_IMM_TYPE]  = { .type = NLA_U32 },
 199         [NFTA_OBJREF_SET_SREG]  = { .type = NLA_U32 },
 200         [NFTA_OBJREF_SET_NAME]  = { .type = NLA_STRING,
 201                                     .len = NFT_SET_MAXNAMELEN - 1 },
 202         [NFTA_OBJREF_SET_ID]    = { .type = NLA_U32 },
 203 };
 204
 205 static struct nft_expr_type nft_objref_type __read_mostly = {
 206         .name           = "objref",
 207         .select_ops     = nft_objref_select_ops,
 208         .policy         = nft_objref_policy,
 209         .maxattr        = NFTA_OBJREF_MAX,
 210         .owner          = THIS_MODULE,
 211 };
 212
 213 static int __init nft_objref_module_init(void)
 214 {
 215         return nft_register_expr(&nft_objref_type);
 216 }
 217
 218 static void __exit nft_objref_module_exit(void)
 219 {
 220         nft_unregister_expr(&nft_objref_type);
 221 }
 222
 223 module_init(nft_objref_module_init);
 224 module_exit(nft_objref_module_exit);
 225
 226 MODULE_LICENSE("GPL");
 227 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 228 MODULE_ALIAS_NFT_EXPR("objref");