Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / net / netfilter / nft_compat.c
diff --git a/kernel/net/netfilter/nft_compat.c b/kernel/net/netfilter/nft_compat.c
new file mode 100644 (file)
index 0000000..7f29cfc
--- /dev/null
@@ -0,0 +1,814 @@
+/*
+ * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nf_tables.h>
+#include <linux/netfilter/nf_tables_compat.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_arp/arp_tables.h>
+#include <net/netfilter/nf_tables.h>
+
+static int nft_compat_chain_validate_dependency(const char *tablename,
+                                               const struct nft_chain *chain)
+{
+       const struct nft_base_chain *basechain;
+
+       if (!tablename || !(chain->flags & NFT_BASE_CHAIN))
+               return 0;
+
+       basechain = nft_base_chain(chain);
+       if (strcmp(tablename, "nat") == 0 &&
+           basechain->type->type != NFT_CHAIN_T_NAT)
+               return -EINVAL;
+
+       return 0;
+}
+
+union nft_entry {
+       struct ipt_entry e4;
+       struct ip6t_entry e6;
+       struct ebt_entry ebt;
+       struct arpt_entry arp;
+};
+
+static inline void
+nft_compat_set_par(struct xt_action_param *par, void *xt, const void *xt_info)
+{
+       par->target     = xt;
+       par->targinfo   = xt_info;
+       par->hotdrop    = false;
+}
+
+static void nft_target_eval_xt(const struct nft_expr *expr,
+                              struct nft_regs *regs,
+                              const struct nft_pktinfo *pkt)
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_target *target = expr->ops->data;
+       struct sk_buff *skb = pkt->skb;
+       int ret;
+
+       nft_compat_set_par((struct xt_action_param *)&pkt->xt, target, info);
+
+       ret = target->target(skb, &pkt->xt);
+
+       if (pkt->xt.hotdrop)
+               ret = NF_DROP;
+
+       switch (ret) {
+       case XT_CONTINUE:
+               regs->verdict.code = NFT_CONTINUE;
+               break;
+       default:
+               regs->verdict.code = ret;
+               break;
+       }
+}
+
+static void nft_target_eval_bridge(const struct nft_expr *expr,
+                                  struct nft_regs *regs,
+                                  const struct nft_pktinfo *pkt)
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_target *target = expr->ops->data;
+       struct sk_buff *skb = pkt->skb;
+       int ret;
+
+       nft_compat_set_par((struct xt_action_param *)&pkt->xt, target, info);
+
+       ret = target->target(skb, &pkt->xt);
+
+       if (pkt->xt.hotdrop)
+               ret = NF_DROP;
+
+       switch (ret) {
+       case EBT_ACCEPT:
+               regs->verdict.code = NF_ACCEPT;
+               break;
+       case EBT_DROP:
+               regs->verdict.code = NF_DROP;
+               break;
+       case EBT_CONTINUE:
+               regs->verdict.code = NFT_CONTINUE;
+               break;
+       case EBT_RETURN:
+               regs->verdict.code = NFT_RETURN;
+               break;
+       default:
+               regs->verdict.code = ret;
+               break;
+       }
+}
+
+static const struct nla_policy nft_target_policy[NFTA_TARGET_MAX + 1] = {
+       [NFTA_TARGET_NAME]      = { .type = NLA_NUL_STRING },
+       [NFTA_TARGET_REV]       = { .type = NLA_U32 },
+       [NFTA_TARGET_INFO]      = { .type = NLA_BINARY },
+};
+
+static void
+nft_target_set_tgchk_param(struct xt_tgchk_param *par,
+                          const struct nft_ctx *ctx,
+                          struct xt_target *target, void *info,
+                          union nft_entry *entry, u16 proto, bool inv)
+{
+       par->net        = ctx->net;
+       par->table      = ctx->table->name;
+       switch (ctx->afi->family) {
+       case AF_INET:
+               entry->e4.ip.proto = proto;
+               entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
+               break;
+       case AF_INET6:
+               if (proto)
+                       entry->e6.ipv6.flags |= IP6T_F_PROTO;
+
+               entry->e6.ipv6.proto = proto;
+               entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
+               break;
+       case NFPROTO_BRIDGE:
+               entry->ebt.ethproto = (__force __be16)proto;
+               entry->ebt.invflags = inv ? EBT_IPROTO : 0;
+               break;
+       case NFPROTO_ARP:
+               break;
+       }
+       par->entryinfo  = entry;
+       par->target     = target;
+       par->targinfo   = info;
+       if (ctx->chain->flags & NFT_BASE_CHAIN) {
+               const struct nft_base_chain *basechain =
+                                               nft_base_chain(ctx->chain);
+               const struct nf_hook_ops *ops = &basechain->ops[0];
+
+               par->hook_mask = 1 << ops->hooknum;
+       } else {
+               par->hook_mask = 0;
+       }
+       par->family     = ctx->afi->family;
+}
+
+static void target_compat_from_user(struct xt_target *t, void *in, void *out)
+{
+       int pad;
+
+       memcpy(out, in, t->targetsize);
+       pad = XT_ALIGN(t->targetsize) - t->targetsize;
+       if (pad > 0)
+               memset(out + t->targetsize, 0, pad);
+}
+
+static const struct nla_policy nft_rule_compat_policy[NFTA_RULE_COMPAT_MAX + 1] = {
+       [NFTA_RULE_COMPAT_PROTO]        = { .type = NLA_U32 },
+       [NFTA_RULE_COMPAT_FLAGS]        = { .type = NLA_U32 },
+};
+
+static int nft_parse_compat(const struct nlattr *attr, u16 *proto, bool *inv)
+{
+       struct nlattr *tb[NFTA_RULE_COMPAT_MAX+1];
+       u32 flags;
+       int err;
+
+       err = nla_parse_nested(tb, NFTA_RULE_COMPAT_MAX, attr,
+                              nft_rule_compat_policy);
+       if (err < 0)
+               return err;
+
+       if (!tb[NFTA_RULE_COMPAT_PROTO] || !tb[NFTA_RULE_COMPAT_FLAGS])
+               return -EINVAL;
+
+       flags = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_FLAGS]));
+       if (flags & ~NFT_RULE_COMPAT_F_MASK)
+               return -EINVAL;
+       if (flags & NFT_RULE_COMPAT_F_INV)
+               *inv = true;
+
+       *proto = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_PROTO]));
+       return 0;
+}
+
+static int
+nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
+               const struct nlattr * const tb[])
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_target *target = expr->ops->data;
+       struct xt_tgchk_param par;
+       size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
+       u16 proto = 0;
+       bool inv = false;
+       union nft_entry e = {};
+       int ret;
+
+       ret = nft_compat_chain_validate_dependency(target->table, ctx->chain);
+       if (ret < 0)
+               goto err;
+
+       target_compat_from_user(target, nla_data(tb[NFTA_TARGET_INFO]), info);
+
+       if (ctx->nla[NFTA_RULE_COMPAT]) {
+               ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
+               if (ret < 0)
+                       goto err;
+       }
+
+       nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
+
+       ret = xt_check_target(&par, size, proto, inv);
+       if (ret < 0)
+               goto err;
+
+       /* The standard target cannot be used */
+       if (target->target == NULL) {
+               ret = -EINVAL;
+               goto err;
+       }
+
+       return 0;
+err:
+       module_put(target->me);
+       return ret;
+}
+
+static void
+nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+       struct xt_target *target = expr->ops->data;
+       void *info = nft_expr_priv(expr);
+       struct xt_tgdtor_param par;
+
+       par.net = ctx->net;
+       par.target = target;
+       par.targinfo = info;
+       par.family = ctx->afi->family;
+       if (par.target->destroy != NULL)
+               par.target->destroy(&par);
+
+       module_put(target->me);
+}
+
+static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       const struct xt_target *target = expr->ops->data;
+       void *info = nft_expr_priv(expr);
+
+       if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||
+           nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||
+           nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(target->targetsize), info))
+               goto nla_put_failure;
+
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static int nft_target_validate(const struct nft_ctx *ctx,
+                              const struct nft_expr *expr,
+                              const struct nft_data **data)
+{
+       struct xt_target *target = expr->ops->data;
+       unsigned int hook_mask = 0;
+       int ret;
+
+       if (ctx->chain->flags & NFT_BASE_CHAIN) {
+               const struct nft_base_chain *basechain =
+                                               nft_base_chain(ctx->chain);
+               const struct nf_hook_ops *ops = &basechain->ops[0];
+
+               hook_mask = 1 << ops->hooknum;
+               if (!(hook_mask & target->hooks))
+                       return -EINVAL;
+
+               ret = nft_compat_chain_validate_dependency(target->table,
+                                                          ctx->chain);
+               if (ret < 0)
+                       return ret;
+       }
+       return 0;
+}
+
+static void nft_match_eval(const struct nft_expr *expr,
+                          struct nft_regs *regs,
+                          const struct nft_pktinfo *pkt)
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_match *match = expr->ops->data;
+       struct sk_buff *skb = pkt->skb;
+       bool ret;
+
+       nft_compat_set_par((struct xt_action_param *)&pkt->xt, match, info);
+
+       ret = match->match(skb, (struct xt_action_param *)&pkt->xt);
+
+       if (pkt->xt.hotdrop) {
+               regs->verdict.code = NF_DROP;
+               return;
+       }
+
+       switch (ret ? 1 : 0) {
+       case 1:
+               regs->verdict.code = NFT_CONTINUE;
+               break;
+       case 0:
+               regs->verdict.code = NFT_BREAK;
+               break;
+       }
+}
+
+static const struct nla_policy nft_match_policy[NFTA_MATCH_MAX + 1] = {
+       [NFTA_MATCH_NAME]       = { .type = NLA_NUL_STRING },
+       [NFTA_MATCH_REV]        = { .type = NLA_U32 },
+       [NFTA_MATCH_INFO]       = { .type = NLA_BINARY },
+};
+
+/* struct xt_mtchk_param and xt_tgchk_param look very similar */
+static void
+nft_match_set_mtchk_param(struct xt_mtchk_param *par, const struct nft_ctx *ctx,
+                         struct xt_match *match, void *info,
+                         union nft_entry *entry, u16 proto, bool inv)
+{
+       par->net        = ctx->net;
+       par->table      = ctx->table->name;
+       switch (ctx->afi->family) {
+       case AF_INET:
+               entry->e4.ip.proto = proto;
+               entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
+               break;
+       case AF_INET6:
+               if (proto)
+                       entry->e6.ipv6.flags |= IP6T_F_PROTO;
+
+               entry->e6.ipv6.proto = proto;
+               entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
+               break;
+       case NFPROTO_BRIDGE:
+               entry->ebt.ethproto = (__force __be16)proto;
+               entry->ebt.invflags = inv ? EBT_IPROTO : 0;
+               break;
+       case NFPROTO_ARP:
+               break;
+       }
+       par->entryinfo  = entry;
+       par->match      = match;
+       par->matchinfo  = info;
+       if (ctx->chain->flags & NFT_BASE_CHAIN) {
+               const struct nft_base_chain *basechain =
+                                               nft_base_chain(ctx->chain);
+               const struct nf_hook_ops *ops = &basechain->ops[0];
+
+               par->hook_mask = 1 << ops->hooknum;
+       } else {
+               par->hook_mask = 0;
+       }
+       par->family     = ctx->afi->family;
+}
+
+static void match_compat_from_user(struct xt_match *m, void *in, void *out)
+{
+       int pad;
+
+       memcpy(out, in, m->matchsize);
+       pad = XT_ALIGN(m->matchsize) - m->matchsize;
+       if (pad > 0)
+               memset(out + m->matchsize, 0, pad);
+}
+
+static int
+nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
+               const struct nlattr * const tb[])
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_match *match = expr->ops->data;
+       struct xt_mtchk_param par;
+       size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO]));
+       u16 proto = 0;
+       bool inv = false;
+       union nft_entry e = {};
+       int ret;
+
+       ret = nft_compat_chain_validate_dependency(match->table, ctx->chain);
+       if (ret < 0)
+               goto err;
+
+       match_compat_from_user(match, nla_data(tb[NFTA_MATCH_INFO]), info);
+
+       if (ctx->nla[NFTA_RULE_COMPAT]) {
+               ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
+               if (ret < 0)
+                       goto err;
+       }
+
+       nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
+
+       ret = xt_check_match(&par, size, proto, inv);
+       if (ret < 0)
+               goto err;
+
+       return 0;
+err:
+       module_put(match->me);
+       return ret;
+}
+
+static void
+nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
+{
+       struct xt_match *match = expr->ops->data;
+       void *info = nft_expr_priv(expr);
+       struct xt_mtdtor_param par;
+
+       par.net = ctx->net;
+       par.match = match;
+       par.matchinfo = info;
+       par.family = ctx->afi->family;
+       if (par.match->destroy != NULL)
+               par.match->destroy(&par);
+
+       module_put(match->me);
+}
+
+static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       void *info = nft_expr_priv(expr);
+       struct xt_match *match = expr->ops->data;
+
+       if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||
+           nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||
+           nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(match->matchsize), info))
+               goto nla_put_failure;
+
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static int nft_match_validate(const struct nft_ctx *ctx,
+                             const struct nft_expr *expr,
+                             const struct nft_data **data)
+{
+       struct xt_match *match = expr->ops->data;
+       unsigned int hook_mask = 0;
+       int ret;
+
+       if (ctx->chain->flags & NFT_BASE_CHAIN) {
+               const struct nft_base_chain *basechain =
+                                               nft_base_chain(ctx->chain);
+               const struct nf_hook_ops *ops = &basechain->ops[0];
+
+               hook_mask = 1 << ops->hooknum;
+               if (!(hook_mask & match->hooks))
+                       return -EINVAL;
+
+               ret = nft_compat_chain_validate_dependency(match->table,
+                                                          ctx->chain);
+               if (ret < 0)
+                       return ret;
+       }
+       return 0;
+}
+
+static int
+nfnl_compat_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
+                     int event, u16 family, const char *name,
+                     int rev, int target)
+{
+       struct nlmsghdr *nlh;
+       struct nfgenmsg *nfmsg;
+       unsigned int flags = portid ? NLM_F_MULTI : 0;
+
+       event |= NFNL_SUBSYS_NFT_COMPAT << 8;
+       nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
+       if (nlh == NULL)
+               goto nlmsg_failure;
+
+       nfmsg = nlmsg_data(nlh);
+       nfmsg->nfgen_family = family;
+       nfmsg->version = NFNETLINK_V0;
+       nfmsg->res_id = 0;
+
+       if (nla_put_string(skb, NFTA_COMPAT_NAME, name) ||
+           nla_put_be32(skb, NFTA_COMPAT_REV, htonl(rev)) ||
+           nla_put_be32(skb, NFTA_COMPAT_TYPE, htonl(target)))
+               goto nla_put_failure;
+
+       nlmsg_end(skb, nlh);
+       return skb->len;
+
+nlmsg_failure:
+nla_put_failure:
+       nlmsg_cancel(skb, nlh);
+       return -1;
+}
+
+static int
+nfnl_compat_get(struct sock *nfnl, struct sk_buff *skb,
+               const struct nlmsghdr *nlh, const struct nlattr * const tb[])
+{
+       int ret = 0, target;
+       struct nfgenmsg *nfmsg;
+       const char *fmt;
+       const char *name;
+       u32 rev;
+       struct sk_buff *skb2;
+
+       if (tb[NFTA_COMPAT_NAME] == NULL ||
+           tb[NFTA_COMPAT_REV] == NULL ||
+           tb[NFTA_COMPAT_TYPE] == NULL)
+               return -EINVAL;
+
+       name = nla_data(tb[NFTA_COMPAT_NAME]);
+       rev = ntohl(nla_get_be32(tb[NFTA_COMPAT_REV]));
+       target = ntohl(nla_get_be32(tb[NFTA_COMPAT_TYPE]));
+
+       nfmsg = nlmsg_data(nlh);
+
+       switch(nfmsg->nfgen_family) {
+       case AF_INET:
+               fmt = "ipt_%s";
+               break;
+       case AF_INET6:
+               fmt = "ip6t_%s";
+               break;
+       case NFPROTO_BRIDGE:
+               fmt = "ebt_%s";
+               break;
+       case NFPROTO_ARP:
+               fmt = "arpt_%s";
+               break;
+       default:
+               pr_err("nft_compat: unsupported protocol %d\n",
+                       nfmsg->nfgen_family);
+               return -EINVAL;
+       }
+
+       try_then_request_module(xt_find_revision(nfmsg->nfgen_family, name,
+                                                rev, target, &ret),
+                                                fmt, name);
+
+       if (ret < 0)
+               return ret;
+
+       skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+       if (skb2 == NULL)
+               return -ENOMEM;
+
+       /* include the best revision for this extension in the message */
+       if (nfnl_compat_fill_info(skb2, NETLINK_CB(skb).portid,
+                                 nlh->nlmsg_seq,
+                                 NFNL_MSG_TYPE(nlh->nlmsg_type),
+                                 NFNL_MSG_COMPAT_GET,
+                                 nfmsg->nfgen_family,
+                                 name, ret, target) <= 0) {
+               kfree_skb(skb2);
+               return -ENOSPC;
+       }
+
+       ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
+                               MSG_DONTWAIT);
+       if (ret > 0)
+               ret = 0;
+
+       return ret == -EAGAIN ? -ENOBUFS : ret;
+}
+
+static const struct nla_policy nfnl_compat_policy_get[NFTA_COMPAT_MAX+1] = {
+       [NFTA_COMPAT_NAME]      = { .type = NLA_NUL_STRING,
+                                   .len = NFT_COMPAT_NAME_MAX-1 },
+       [NFTA_COMPAT_REV]       = { .type = NLA_U32 },
+       [NFTA_COMPAT_TYPE]      = { .type = NLA_U32 },
+};
+
+static const struct nfnl_callback nfnl_nft_compat_cb[NFNL_MSG_COMPAT_MAX] = {
+       [NFNL_MSG_COMPAT_GET]           = { .call = nfnl_compat_get,
+                                           .attr_count = NFTA_COMPAT_MAX,
+                                           .policy = nfnl_compat_policy_get },
+};
+
+static const struct nfnetlink_subsystem nfnl_compat_subsys = {
+       .name           = "nft-compat",
+       .subsys_id      = NFNL_SUBSYS_NFT_COMPAT,
+       .cb_count       = NFNL_MSG_COMPAT_MAX,
+       .cb             = nfnl_nft_compat_cb,
+};
+
+static LIST_HEAD(nft_match_list);
+
+struct nft_xt {
+       struct list_head        head;
+       struct nft_expr_ops     ops;
+};
+
+static struct nft_expr_type nft_match_type;
+
+static const struct nft_expr_ops *
+nft_match_select_ops(const struct nft_ctx *ctx,
+                    const struct nlattr * const tb[])
+{
+       struct nft_xt *nft_match;
+       struct xt_match *match;
+       char *mt_name;
+       __u32 rev, family;
+
+       if (tb[NFTA_MATCH_NAME] == NULL ||
+           tb[NFTA_MATCH_REV] == NULL ||
+           tb[NFTA_MATCH_INFO] == NULL)
+               return ERR_PTR(-EINVAL);
+
+       mt_name = nla_data(tb[NFTA_MATCH_NAME]);
+       rev = ntohl(nla_get_be32(tb[NFTA_MATCH_REV]));
+       family = ctx->afi->family;
+
+       /* Re-use the existing match if it's already loaded. */
+       list_for_each_entry(nft_match, &nft_match_list, head) {
+               struct xt_match *match = nft_match->ops.data;
+
+               if (strcmp(match->name, mt_name) == 0 &&
+                   match->revision == rev && match->family == family) {
+                       if (!try_module_get(match->me))
+                               return ERR_PTR(-ENOENT);
+
+                       return &nft_match->ops;
+               }
+       }
+
+       match = xt_request_find_match(family, mt_name, rev);
+       if (IS_ERR(match))
+               return ERR_PTR(-ENOENT);
+
+       /* This is the first time we use this match, allocate operations */
+       nft_match = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
+       if (nft_match == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       nft_match->ops.type = &nft_match_type;
+       nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));
+       nft_match->ops.eval = nft_match_eval;
+       nft_match->ops.init = nft_match_init;
+       nft_match->ops.destroy = nft_match_destroy;
+       nft_match->ops.dump = nft_match_dump;
+       nft_match->ops.validate = nft_match_validate;
+       nft_match->ops.data = match;
+
+       list_add(&nft_match->head, &nft_match_list);
+
+       return &nft_match->ops;
+}
+
+static void nft_match_release(void)
+{
+       struct nft_xt *nft_match, *tmp;
+
+       list_for_each_entry_safe(nft_match, tmp, &nft_match_list, head)
+               kfree(nft_match);
+}
+
+static struct nft_expr_type nft_match_type __read_mostly = {
+       .name           = "match",
+       .select_ops     = nft_match_select_ops,
+       .policy         = nft_match_policy,
+       .maxattr        = NFTA_MATCH_MAX,
+       .owner          = THIS_MODULE,
+};
+
+static LIST_HEAD(nft_target_list);
+
+static struct nft_expr_type nft_target_type;
+
+static const struct nft_expr_ops *
+nft_target_select_ops(const struct nft_ctx *ctx,
+                     const struct nlattr * const tb[])
+{
+       struct nft_xt *nft_target;
+       struct xt_target *target;
+       char *tg_name;
+       __u32 rev, family;
+
+       if (tb[NFTA_TARGET_NAME] == NULL ||
+           tb[NFTA_TARGET_REV] == NULL ||
+           tb[NFTA_TARGET_INFO] == NULL)
+               return ERR_PTR(-EINVAL);
+
+       tg_name = nla_data(tb[NFTA_TARGET_NAME]);
+       rev = ntohl(nla_get_be32(tb[NFTA_TARGET_REV]));
+       family = ctx->afi->family;
+
+       /* Re-use the existing target if it's already loaded. */
+       list_for_each_entry(nft_target, &nft_target_list, head) {
+               struct xt_target *target = nft_target->ops.data;
+
+               if (strcmp(target->name, tg_name) == 0 &&
+                   target->revision == rev && target->family == family) {
+                       if (!try_module_get(target->me))
+                               return ERR_PTR(-ENOENT);
+
+                       return &nft_target->ops;
+               }
+       }
+
+       target = xt_request_find_target(family, tg_name, rev);
+       if (IS_ERR(target))
+               return ERR_PTR(-ENOENT);
+
+       /* This is the first time we use this target, allocate operations */
+       nft_target = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
+       if (nft_target == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       nft_target->ops.type = &nft_target_type;
+       nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
+       nft_target->ops.init = nft_target_init;
+       nft_target->ops.destroy = nft_target_destroy;
+       nft_target->ops.dump = nft_target_dump;
+       nft_target->ops.validate = nft_target_validate;
+       nft_target->ops.data = target;
+
+       if (family == NFPROTO_BRIDGE)
+               nft_target->ops.eval = nft_target_eval_bridge;
+       else
+               nft_target->ops.eval = nft_target_eval_xt;
+
+       list_add(&nft_target->head, &nft_target_list);
+
+       return &nft_target->ops;
+}
+
+static void nft_target_release(void)
+{
+       struct nft_xt *nft_target, *tmp;
+
+       list_for_each_entry_safe(nft_target, tmp, &nft_target_list, head)
+               kfree(nft_target);
+}
+
+static struct nft_expr_type nft_target_type __read_mostly = {
+       .name           = "target",
+       .select_ops     = nft_target_select_ops,
+       .policy         = nft_target_policy,
+       .maxattr        = NFTA_TARGET_MAX,
+       .owner          = THIS_MODULE,
+};
+
+static int __init nft_compat_module_init(void)
+{
+       int ret;
+
+       ret = nft_register_expr(&nft_match_type);
+       if (ret < 0)
+               return ret;
+
+       ret = nft_register_expr(&nft_target_type);
+       if (ret < 0)
+               goto err_match;
+
+       ret = nfnetlink_subsys_register(&nfnl_compat_subsys);
+       if (ret < 0) {
+               pr_err("nft_compat: cannot register with nfnetlink.\n");
+               goto err_target;
+       }
+
+       pr_info("nf_tables_compat: (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>\n");
+
+       return ret;
+
+err_target:
+       nft_unregister_expr(&nft_target_type);
+err_match:
+       nft_unregister_expr(&nft_match_type);
+       return ret;
+}
+
+static void __exit nft_compat_module_exit(void)
+{
+       nfnetlink_subsys_unregister(&nfnl_compat_subsys);
+       nft_unregister_expr(&nft_target_type);
+       nft_unregister_expr(&nft_match_type);
+       nft_match_release();
+       nft_target_release();
+}
+
+MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
+
+module_init(nft_compat_module_init);
+module_exit(nft_compat_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_EXPR("match");
+MODULE_ALIAS_NFT_EXPR("target");