// SPDX-License-Identifier: GPL-2.0-only
/*
 * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * 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>
#include <net/netfilter/nf_log.h>

/* Used for matches where *info is larger than X byte */
#define NFT_MATCH_LARGE_THRESH  192

struct nft_xt_match_priv {
        void *info;
};

static int nft_compat_chain_validate_dependency(const struct nft_ctx *ctx,
                                                const char *tablename)
{
        enum nft_chain_types type = NFT_CHAIN_T_DEFAULT;
        const struct nft_chain *chain = ctx->chain;
        const struct nft_base_chain *basechain;

        if (!tablename ||
            !nft_is_base_chain(chain))
                return 0;

        basechain = nft_base_chain(chain);
        if (strcmp(tablename, "nat") == 0) {
                if (ctx->family != NFPROTO_BRIDGE)
                        type = NFT_CHAIN_T_NAT;
                if (basechain->type->type != type)
                        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,
                   const struct nft_pktinfo *pkt,
                   const void *xt, const void *xt_info)
{
        par->state      = pkt->state;
        par->thoff      = nft_thoff(pkt);
        par->fragoff    = pkt->fragoff;
        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;
        struct xt_action_param xt;
        int ret;

        nft_compat_set_par(&xt, pkt, target, info);

        ret = target->target(skb, &xt);

        if (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;
        struct xt_action_param xt;
        int ret;

        nft_compat_set_par(&xt, pkt, target, info);

        ret = target->target(skb, &xt);

        if (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,
                                    .len = XT_EXTENSION_MAXNAMELEN, },
        [NFTA_TARGET_REV]       = NLA_POLICY_MAX(NLA_BE32, 255),
        [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->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 (nft_is_base_chain(ctx->chain)) {
                const struct nft_base_chain *basechain =
                                                nft_base_chain(ctx->chain);
                const struct nf_hook_ops *ops = &basechain->ops;

                par->hook_mask = 1 << ops->hooknum;
        } else {
                par->hook_mask = 0;
        }
        par->family     = ctx->family;
        par->nft_compat = true;
}

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 l4proto;
        u32 flags;
        int err;

        err = nla_parse_nested_deprecated(tb, NFTA_RULE_COMPAT_MAX, attr,
                                          nft_rule_compat_policy, NULL);
        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_UNUSED ||
            flags & ~NFT_RULE_COMPAT_F_MASK)
                return -EINVAL;
        if (flags & NFT_RULE_COMPAT_F_INV)
                *inv = true;

        l4proto = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_PROTO]));
        if (l4proto > U16_MAX)
                return -EINVAL;

        *proto = l4proto;

        return 0;
}

static void nft_compat_wait_for_destructors(struct net *net)
{
        /* xtables matches or targets can have side effects, e.g.
         * creation/destruction of /proc files.
         * The xt ->destroy functions are run asynchronously from
         * work queue.  If we have pending invocations we thus
         * need to wait for those to finish.
         */
        nf_tables_trans_destroy_flush_work(net);
}

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;

        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)
                        return ret;
        }

        nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);

        nft_compat_wait_for_destructors(ctx->net);

        ret = xt_check_target(&par, size, proto, inv);
        if (ret < 0) {
                if (ret == -ENOENT) {
                        const char *modname = NULL;

                        if (strcmp(target->name, "LOG") == 0)
                                modname = "nf_log_syslog";
                        else if (strcmp(target->name, "NFLOG") == 0)
                                modname = "nfnetlink_log";

                        if (modname &&
                            nft_request_module(ctx->net, "%s", modname) == -EAGAIN)
                                return -EAGAIN;
                }

                return ret;
        }

        /* The standard target cannot be used */
        if (!target->target)
                return -EINVAL;

        return 0;
}

static void __nft_mt_tg_destroy(struct module *me, const struct nft_expr *expr)
{
        module_put(me);
        kfree(expr->ops);
}

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 module *me = target->me;
        struct xt_tgdtor_param par;

        par.net = ctx->net;
        par.target = target;
        par.targinfo = info;
        par.family = ctx->family;
        if (par.target->destroy != NULL)
                par.target->destroy(&par);

        __nft_mt_tg_destroy(me, expr);
}

static int nft_extension_dump_info(struct sk_buff *skb, int attr,
                                   const void *info,
                                   unsigned int size, unsigned int user_size)
{
        unsigned int info_size, aligned_size = XT_ALIGN(size);
        struct nlattr *nla;

        nla = nla_reserve(skb, attr, aligned_size);
        if (!nla)
                return -1;

        info_size = user_size ? : size;
        memcpy(nla_data(nla), info, info_size);
        memset(nla_data(nla) + info_size, 0, aligned_size - info_size);

        return 0;
}

static int nft_target_dump(struct sk_buff *skb,
                           const struct nft_expr *expr, bool reset)
{
        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)) ||
            nft_extension_dump_info(skb, NFTA_TARGET_INFO, info,
                                    target->targetsize, target->usersize))
                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)
{
        struct xt_target *target = expr->ops->data;
        unsigned int hook_mask = 0;
        int ret;

        if (ctx->family != NFPROTO_IPV4 &&
            ctx->family != NFPROTO_IPV6 &&
            ctx->family != NFPROTO_INET &&
            ctx->family != NFPROTO_BRIDGE &&
            ctx->family != NFPROTO_ARP)
                return -EOPNOTSUPP;

        ret = nft_chain_validate_hooks(ctx->chain,
                                       (1 << NF_INET_PRE_ROUTING) |
                                       (1 << NF_INET_LOCAL_IN) |
                                       (1 << NF_INET_FORWARD) |
                                       (1 << NF_INET_LOCAL_OUT) |
                                       (1 << NF_INET_POST_ROUTING));
        if (ret)
                return ret;

        if (nft_is_base_chain(ctx->chain)) {
                const struct nft_base_chain *basechain =
                                                nft_base_chain(ctx->chain);
                const struct nf_hook_ops *ops = &basechain->ops;

                hook_mask = 1 << ops->hooknum;
                if (target->hooks && !(hook_mask & target->hooks))
                        return -EINVAL;

                ret = nft_compat_chain_validate_dependency(ctx, target->table);
                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)
{
        struct xt_match *match = expr->ops->data;
        struct sk_buff *skb = pkt->skb;
        struct xt_action_param xt;
        bool ret;

        nft_compat_set_par(&xt, pkt, match, info);

        ret = match->match(skb, &xt);

        if (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 void nft_match_large_eval(const struct nft_expr *expr,
                                 struct nft_regs *regs,
                                 const struct nft_pktinfo *pkt)
{
        struct nft_xt_match_priv *priv = nft_expr_priv(expr);

        __nft_match_eval(expr, regs, pkt, priv->info);
}

static void nft_match_eval(const struct nft_expr *expr,
                           struct nft_regs *regs,
                           const struct nft_pktinfo *pkt)
{
        __nft_match_eval(expr, regs, pkt, nft_expr_priv(expr));
}

static const struct nla_policy nft_match_policy[NFTA_MATCH_MAX + 1] = {
        [NFTA_MATCH_NAME]       = { .type = NLA_NUL_STRING,
                                    .len = XT_EXTENSION_MAXNAMELEN },
        [NFTA_MATCH_REV]        = NLA_POLICY_MAX(NLA_BE32, 255),
        [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->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 (nft_is_base_chain(ctx->chain)) {
                const struct nft_base_chain *basechain =
                                                nft_base_chain(ctx->chain);
                const struct nf_hook_ops *ops = &basechain->ops;

                par->hook_mask = 1 << ops->hooknum;
        } else {
                par->hook_mask = 0;
        }
        par->family     = ctx->family;
        par->nft_compat = true;
}

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)
{
        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;

        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)
                        return ret;
        }

        nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);

        nft_compat_wait_for_destructors(ctx->net);

        return xt_check_match(&par, size, proto, inv);
}

static int
nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
               const struct nlattr * const tb[])
{
        return __nft_match_init(ctx, expr, tb, nft_expr_priv(expr));
}

static int
nft_match_large_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
                     const struct nlattr * const tb[])
{
        struct nft_xt_match_priv *priv = nft_expr_priv(expr);
        struct xt_match *m = expr->ops->data;
        int ret;

        priv->info = kmalloc(XT_ALIGN(m->matchsize), GFP_KERNEL_ACCOUNT);
        if (!priv->info)
                return -ENOMEM;

        ret = __nft_match_init(ctx, expr, tb, priv->info);
        if (ret)
                kfree(priv->info);
        return ret;
}

static void
__nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,
                    void *info)
{
        struct xt_match *match = expr->ops->data;
        struct module *me = match->me;
        struct xt_mtdtor_param par;

        par.net = ctx->net;
        par.match = match;
        par.matchinfo = info;
        par.family = ctx->family;
        if (par.match->destroy != NULL)
                par.match->destroy(&par);

        __nft_mt_tg_destroy(me, expr);
}

static void
nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
{
        __nft_match_destroy(ctx, expr, nft_expr_priv(expr));
}

static void
nft_match_large_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
{
        struct nft_xt_match_priv *priv = nft_expr_priv(expr);

        __nft_match_destroy(ctx, expr, priv->info);
        kfree(priv->info);
}

static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr,
                            void *info)
{
        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)) ||
            nft_extension_dump_info(skb, NFTA_MATCH_INFO, info,
                                    match->matchsize, match->usersize))
                goto nla_put_failure;

        return 0;

nla_put_failure:
        return -1;
}

static int nft_match_dump(struct sk_buff *skb,
                          const struct nft_expr *expr, bool reset)
{
        return __nft_match_dump(skb, expr, nft_expr_priv(expr));
}

static int nft_match_large_dump(struct sk_buff *skb,
                                const struct nft_expr *e, bool reset)
{
        struct nft_xt_match_priv *priv = nft_expr_priv(e);

        return __nft_match_dump(skb, e, priv->info);
}

static int nft_match_validate(const struct nft_ctx *ctx,
                              const struct nft_expr *expr)
{
        struct xt_match *match = expr->ops->data;
        unsigned int hook_mask = 0;
        int ret;

        if (ctx->family != NFPROTO_IPV4 &&
            ctx->family != NFPROTO_IPV6 &&
            ctx->family != NFPROTO_INET &&
            ctx->family != NFPROTO_BRIDGE &&
            ctx->family != NFPROTO_ARP)
                return -EOPNOTSUPP;

        ret = nft_chain_validate_hooks(ctx->chain,
                                       (1 << NF_INET_PRE_ROUTING) |
                                       (1 << NF_INET_LOCAL_IN) |
                                       (1 << NF_INET_FORWARD) |
                                       (1 << NF_INET_LOCAL_OUT) |
                                       (1 << NF_INET_POST_ROUTING));
        if (ret)
                return ret;

        if (nft_is_base_chain(ctx->chain)) {
                const struct nft_base_chain *basechain =
                                                nft_base_chain(ctx->chain);
                const struct nf_hook_ops *ops = &basechain->ops;

                hook_mask = 1 << ops->hooknum;
                if (match->hooks && !(hook_mask & match->hooks))
                        return -EINVAL;

                ret = nft_compat_chain_validate_dependency(ctx, match->table);
                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;
        unsigned int flags = portid ? NLM_F_MULTI : 0;

        event = nfnl_msg_type(NFNL_SUBSYS_NFT_COMPAT, event);
        nlh = nfnl_msg_put(skb, portid, seq, event, flags, family,
                           NFNETLINK_V0, 0);
        if (!nlh)
                goto nlmsg_failure;

        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_rcu(struct sk_buff *skb,
                               const struct nfnl_info *info,
                               const struct nlattr * const tb[])
{
        u8 family = info->nfmsg->nfgen_family;
        const char *name, *fmt;
        struct sk_buff *skb2;
        int ret = 0, target;
        u32 rev;

        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]));
        /* x_tables api checks for 'target == 1' to mean target,
         * everything else means 'match'.
         * In x_tables world, the number is set by kernel, not
         * userspace.
         */
        target = nla_get_be32(tb[NFTA_COMPAT_TYPE]) == htonl(1);

        switch(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", family);
                return -EINVAL;
        }

        if (!try_module_get(THIS_MODULE))
                return -EINVAL;

        rcu_read_unlock();
        try_then_request_module(xt_find_revision(family, name, rev, target, &ret),
                                fmt, name);
        if (ret < 0)
                goto out_put;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (skb2 == NULL) {
                ret = -ENOMEM;
                goto out_put;
        }

        /* include the best revision for this extension in the message */
        if (nfnl_compat_fill_info(skb2, NETLINK_CB(skb).portid,
                                  info->nlh->nlmsg_seq,
                                  NFNL_MSG_TYPE(info->nlh->nlmsg_type),
                                  NFNL_MSG_COMPAT_GET,
                                  family, name, ret, target) <= 0) {
                kfree_skb(skb2);
                goto out_put;
        }

        ret = nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
out_put:
        rcu_read_lock();
        module_put(THIS_MODULE);

        return 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]       = NLA_POLICY_MAX(NLA_BE32, 255),
        [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_rcu,
                .type           = NFNL_CB_RCU,
                .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 struct nft_expr_type nft_match_type;

static bool nft_match_reduce(struct nft_regs_track *track,
                             const struct nft_expr *expr)
{
        const struct xt_match *match = expr->ops->data;

        return strcmp(match->name, "comment") == 0;
}

static const struct nft_expr_ops *
nft_match_select_ops(const struct nft_ctx *ctx,
                     const struct nlattr * const tb[])
{
        struct nft_expr_ops *ops;
        struct xt_match *match;
        unsigned int matchsize;
        char *mt_name;
        u32 rev, family;
        int err;

        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->family;

        match = xt_request_find_match(family, mt_name, rev);
        if (IS_ERR(match))
                return ERR_PTR(-ENOENT);

        if (match->matchsize > nla_len(tb[NFTA_MATCH_INFO])) {
                err = -EINVAL;
                goto err;
        }

        ops = kzalloc_obj(struct nft_expr_ops, GFP_KERNEL_ACCOUNT);
        if (!ops) {
                err = -ENOMEM;
                goto err;
        }

        ops->type = &nft_match_type;
        ops->eval = nft_match_eval;
        ops->init = nft_match_init;
        ops->destroy = nft_match_destroy;
        ops->dump = nft_match_dump;
        ops->validate = nft_match_validate;
        ops->data = match;
        ops->reduce = nft_match_reduce;

        matchsize = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));
        if (matchsize > NFT_MATCH_LARGE_THRESH) {
                matchsize = NFT_EXPR_SIZE(sizeof(struct nft_xt_match_priv));

                ops->eval = nft_match_large_eval;
                ops->init = nft_match_large_init;
                ops->destroy = nft_match_large_destroy;
                ops->dump = nft_match_large_dump;
        }

        ops->size = matchsize;

        return ops;
err:
        module_put(match->me);
        return ERR_PTR(err);
}

static void nft_match_release_ops(const struct nft_expr_ops *ops)
{
        struct xt_match *match = ops->data;

        module_put(match->me);
        kfree(ops);
}

static struct nft_expr_type nft_match_type __read_mostly = {
        .name           = "match",
        .select_ops     = nft_match_select_ops,
        .release_ops    = nft_match_release_ops,
        .policy         = nft_match_policy,
        .maxattr        = NFTA_MATCH_MAX,
        .owner          = THIS_MODULE,
};

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_expr_ops *ops;
        struct xt_target *target;
        char *tg_name;
        u32 rev, family;
        int err;

        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->family;

        if (strcmp(tg_name, XT_ERROR_TARGET) == 0 ||
            strcmp(tg_name, XT_STANDARD_TARGET) == 0 ||
            strcmp(tg_name, "standard") == 0)
                return ERR_PTR(-EINVAL);

        target = xt_request_find_target(family, tg_name, rev);
        if (IS_ERR(target))
                return ERR_PTR(-ENOENT);

        if (!target->target) {
                err = -EINVAL;
                goto err;
        }

        if (target->targetsize > nla_len(tb[NFTA_TARGET_INFO])) {
                err = -EINVAL;
                goto err;
        }

        ops = kzalloc_obj(struct nft_expr_ops, GFP_KERNEL_ACCOUNT);
        if (!ops) {
                err = -ENOMEM;
                goto err;
        }

        ops->type = &nft_target_type;
        ops->size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
        ops->init = nft_target_init;
        ops->destroy = nft_target_destroy;
        ops->dump = nft_target_dump;
        ops->validate = nft_target_validate;
        ops->data = target;
        ops->reduce = NFT_REDUCE_READONLY;

        if (family == NFPROTO_BRIDGE)
                ops->eval = nft_target_eval_bridge;
        else
                ops->eval = nft_target_eval_xt;

        return ops;
err:
        module_put(target->me);
        return ERR_PTR(err);
}

static void nft_target_release_ops(const struct nft_expr_ops *ops)
{
        struct xt_target *target = ops->data;

        module_put(target->me);
        kfree(ops);
}

static struct nft_expr_type nft_target_type __read_mostly = {
        .name           = "target",
        .select_ops     = nft_target_select_ops,
        .release_ops    = nft_target_release_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;
        }

        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);
}

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");
MODULE_DESCRIPTION("x_tables over nftables support");