// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2007-2009 Patrick McHardy <kaber@trash.net>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/vmalloc.h>
#include <linux/rhashtable.h>
#include <linux/audit.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_flow_table.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_offload.h>
#include <net/net_namespace.h>
#include <net/sock.h>

#define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-"))

static LIST_HEAD(nf_tables_expressions);
static LIST_HEAD(nf_tables_objects);
static LIST_HEAD(nf_tables_flowtables);
static LIST_HEAD(nf_tables_destroy_list);
static DEFINE_SPINLOCK(nf_tables_destroy_list_lock);
static u64 table_handle;

enum {
        NFT_VALIDATE_SKIP       = 0,
        NFT_VALIDATE_NEED,
        NFT_VALIDATE_DO,
};

static struct rhltable nft_objname_ht;

static u32 nft_chain_hash(const void *data, u32 len, u32 seed);
static u32 nft_chain_hash_obj(const void *data, u32 len, u32 seed);
static int nft_chain_hash_cmp(struct rhashtable_compare_arg *, const void *);

static u32 nft_objname_hash(const void *data, u32 len, u32 seed);
static u32 nft_objname_hash_obj(const void *data, u32 len, u32 seed);
static int nft_objname_hash_cmp(struct rhashtable_compare_arg *, const void *);

static const struct rhashtable_params nft_chain_ht_params = {
        .head_offset            = offsetof(struct nft_chain, rhlhead),
        .key_offset             = offsetof(struct nft_chain, name),
        .hashfn                 = nft_chain_hash,
        .obj_hashfn             = nft_chain_hash_obj,
        .obj_cmpfn              = nft_chain_hash_cmp,
        .automatic_shrinking    = true,
};

static const struct rhashtable_params nft_objname_ht_params = {
        .head_offset            = offsetof(struct nft_object, rhlhead),
        .key_offset             = offsetof(struct nft_object, key),
        .hashfn                 = nft_objname_hash,
        .obj_hashfn             = nft_objname_hash_obj,
        .obj_cmpfn              = nft_objname_hash_cmp,
        .automatic_shrinking    = true,
};

static void nft_validate_state_update(struct net *net, u8 new_validate_state)
{
        switch (net->nft.validate_state) {
        case NFT_VALIDATE_SKIP:
                WARN_ON_ONCE(new_validate_state == NFT_VALIDATE_DO);
                break;
        case NFT_VALIDATE_NEED:
                break;
        case NFT_VALIDATE_DO:
                if (new_validate_state == NFT_VALIDATE_NEED)
                        return;
        }

        net->nft.validate_state = new_validate_state;
}
static void nf_tables_trans_destroy_work(struct work_struct *w);
static DECLARE_WORK(trans_destroy_work, nf_tables_trans_destroy_work);

static void nft_ctx_init(struct nft_ctx *ctx,
                         struct net *net,
                         const struct sk_buff *skb,
                         const struct nlmsghdr *nlh,
                         u8 family,
                         struct nft_table *table,
                         struct nft_chain *chain,
                         const struct nlattr * const *nla)
{
        ctx->net        = net;
        ctx->family     = family;
        ctx->level      = 0;
        ctx->table      = table;
        ctx->chain      = chain;
        ctx->nla        = nla;
        ctx->portid     = NETLINK_CB(skb).portid;
        ctx->report     = nlmsg_report(nlh);
        ctx->flags      = nlh->nlmsg_flags;
        ctx->seq        = nlh->nlmsg_seq;
}

static struct nft_trans *nft_trans_alloc_gfp(const struct nft_ctx *ctx,
                                             int msg_type, u32 size, gfp_t gfp)
{
        struct nft_trans *trans;

        trans = kzalloc(sizeof(struct nft_trans) + size, gfp);
        if (trans == NULL)
                return NULL;

        trans->msg_type = msg_type;
        trans->ctx      = *ctx;

        return trans;
}

static struct nft_trans *nft_trans_alloc(const struct nft_ctx *ctx,
                                         int msg_type, u32 size)
{
        return nft_trans_alloc_gfp(ctx, msg_type, size, GFP_KERNEL);
}

static void nft_trans_destroy(struct nft_trans *trans)
{
        list_del(&trans->list);
        kfree(trans);
}

static void nft_set_trans_bind(const struct nft_ctx *ctx, struct nft_set *set)
{
        struct net *net = ctx->net;
        struct nft_trans *trans;

        if (!nft_set_is_anonymous(set))
                return;

        list_for_each_entry_reverse(trans, &net->nft.commit_list, list) {
                switch (trans->msg_type) {
                case NFT_MSG_NEWSET:
                        if (nft_trans_set(trans) == set)
                                nft_trans_set_bound(trans) = true;
                        break;
                case NFT_MSG_NEWSETELEM:
                        if (nft_trans_elem_set(trans) == set)
                                nft_trans_elem_set_bound(trans) = true;
                        break;
                }
        }
}

static int nft_netdev_register_hooks(struct net *net,
                                     struct list_head *hook_list)
{
        struct nft_hook *hook;
        int err, j;

        j = 0;
        list_for_each_entry(hook, hook_list, list) {
                err = nf_register_net_hook(net, &hook->ops);
                if (err < 0)
                        goto err_register;

                j++;
        }
        return 0;

err_register:
        list_for_each_entry(hook, hook_list, list) {
                if (j-- <= 0)
                        break;

                nf_unregister_net_hook(net, &hook->ops);
        }
        return err;
}

static void nft_netdev_unregister_hooks(struct net *net,
                                        struct list_head *hook_list)
{
        struct nft_hook *hook;

        list_for_each_entry(hook, hook_list, list)
                nf_unregister_net_hook(net, &hook->ops);
}

static int nf_tables_register_hook(struct net *net,
                                   const struct nft_table *table,
                                   struct nft_chain *chain)
{
        struct nft_base_chain *basechain;
        const struct nf_hook_ops *ops;

        if (table->flags & NFT_TABLE_F_DORMANT ||
            !nft_is_base_chain(chain))
                return 0;

        basechain = nft_base_chain(chain);
        ops = &basechain->ops;

        if (basechain->type->ops_register)
                return basechain->type->ops_register(net, ops);

        if (nft_base_chain_netdev(table->family, basechain->ops.hooknum))
                return nft_netdev_register_hooks(net, &basechain->hook_list);

        return nf_register_net_hook(net, &basechain->ops);
}

static void nf_tables_unregister_hook(struct net *net,
                                      const struct nft_table *table,
                                      struct nft_chain *chain)
{
        struct nft_base_chain *basechain;
        const struct nf_hook_ops *ops;

        if (table->flags & NFT_TABLE_F_DORMANT ||
            !nft_is_base_chain(chain))
                return;
        basechain = nft_base_chain(chain);
        ops = &basechain->ops;

        if (basechain->type->ops_unregister)
                return basechain->type->ops_unregister(net, ops);

        if (nft_base_chain_netdev(table->family, basechain->ops.hooknum))
                nft_netdev_unregister_hooks(net, &basechain->hook_list);
        else
                nf_unregister_net_hook(net, &basechain->ops);
}

static int nft_trans_table_add(struct nft_ctx *ctx, int msg_type)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type, sizeof(struct nft_trans_table));
        if (trans == NULL)
                return -ENOMEM;

        if (msg_type == NFT_MSG_NEWTABLE)
                nft_activate_next(ctx->net, ctx->table);

        list_add_tail(&trans->list, &ctx->net->nft.commit_list);
        return 0;
}

static int nft_deltable(struct nft_ctx *ctx)
{
        int err;

        err = nft_trans_table_add(ctx, NFT_MSG_DELTABLE);
        if (err < 0)
                return err;

        nft_deactivate_next(ctx->net, ctx->table);
        return err;
}

static struct nft_trans *nft_trans_chain_add(struct nft_ctx *ctx, int msg_type)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type, sizeof(struct nft_trans_chain));
        if (trans == NULL)
                return ERR_PTR(-ENOMEM);

        if (msg_type == NFT_MSG_NEWCHAIN) {
                nft_activate_next(ctx->net, ctx->chain);

                if (ctx->nla[NFTA_CHAIN_ID]) {
                        nft_trans_chain_id(trans) =
                                ntohl(nla_get_be32(ctx->nla[NFTA_CHAIN_ID]));
                }
        }

        list_add_tail(&trans->list, &ctx->net->nft.commit_list);
        return trans;
}

static int nft_delchain(struct nft_ctx *ctx)
{
        struct nft_trans *trans;

        trans = nft_trans_chain_add(ctx, NFT_MSG_DELCHAIN);
        if (IS_ERR(trans))
                return PTR_ERR(trans);

        ctx->table->use--;
        nft_deactivate_next(ctx->net, ctx->chain);

        return 0;
}

static void nft_rule_expr_activate(const struct nft_ctx *ctx,
                                   struct nft_rule *rule)
{
        struct nft_expr *expr;

        expr = nft_expr_first(rule);
        while (nft_expr_more(rule, expr)) {
                if (expr->ops->activate)
                        expr->ops->activate(ctx, expr);

                expr = nft_expr_next(expr);
        }
}

static void nft_rule_expr_deactivate(const struct nft_ctx *ctx,
                                     struct nft_rule *rule,
                                     enum nft_trans_phase phase)
{
        struct nft_expr *expr;

        expr = nft_expr_first(rule);
        while (nft_expr_more(rule, expr)) {
                if (expr->ops->deactivate)
                        expr->ops->deactivate(ctx, expr, phase);

                expr = nft_expr_next(expr);
        }
}

static int
nf_tables_delrule_deactivate(struct nft_ctx *ctx, struct nft_rule *rule)
{
        /* You cannot delete the same rule twice */
        if (nft_is_active_next(ctx->net, rule)) {
                nft_deactivate_next(ctx->net, rule);
                ctx->chain->use--;
                return 0;
        }
        return -ENOENT;
}

static struct nft_trans *nft_trans_rule_add(struct nft_ctx *ctx, int msg_type,
                                            struct nft_rule *rule)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type, sizeof(struct nft_trans_rule));
        if (trans == NULL)
                return NULL;

        if (msg_type == NFT_MSG_NEWRULE && ctx->nla[NFTA_RULE_ID] != NULL) {
                nft_trans_rule_id(trans) =
                        ntohl(nla_get_be32(ctx->nla[NFTA_RULE_ID]));
        }
        nft_trans_rule(trans) = rule;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);

        return trans;
}

static int nft_delrule(struct nft_ctx *ctx, struct nft_rule *rule)
{
        struct nft_flow_rule *flow;
        struct nft_trans *trans;
        int err;

        trans = nft_trans_rule_add(ctx, NFT_MSG_DELRULE, rule);
        if (trans == NULL)
                return -ENOMEM;

        if (ctx->chain->flags & NFT_CHAIN_HW_OFFLOAD) {
                flow = nft_flow_rule_create(ctx->net, rule);
                if (IS_ERR(flow)) {
                        nft_trans_destroy(trans);
                        return PTR_ERR(flow);
                }

                nft_trans_flow_rule(trans) = flow;
        }

        err = nf_tables_delrule_deactivate(ctx, rule);
        if (err < 0) {
                nft_trans_destroy(trans);
                return err;
        }
        nft_rule_expr_deactivate(ctx, rule, NFT_TRANS_PREPARE);

        return 0;
}

static int nft_delrule_by_chain(struct nft_ctx *ctx)
{
        struct nft_rule *rule;
        int err;

        list_for_each_entry(rule, &ctx->chain->rules, list) {
                if (!nft_is_active_next(ctx->net, rule))
                        continue;

                err = nft_delrule(ctx, rule);
                if (err < 0)
                        return err;
        }
        return 0;
}

static int nft_trans_set_add(const struct nft_ctx *ctx, int msg_type,
                             struct nft_set *set)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type, sizeof(struct nft_trans_set));
        if (trans == NULL)
                return -ENOMEM;

        if (msg_type == NFT_MSG_NEWSET && ctx->nla[NFTA_SET_ID] != NULL) {
                nft_trans_set_id(trans) =
                        ntohl(nla_get_be32(ctx->nla[NFTA_SET_ID]));
                nft_activate_next(ctx->net, set);
        }
        nft_trans_set(trans) = set;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);

        return 0;
}

static int nft_delset(const struct nft_ctx *ctx, struct nft_set *set)
{
        int err;

        err = nft_trans_set_add(ctx, NFT_MSG_DELSET, set);
        if (err < 0)
                return err;

        nft_deactivate_next(ctx->net, set);
        ctx->table->use--;

        return err;
}

static int nft_trans_obj_add(struct nft_ctx *ctx, int msg_type,
                             struct nft_object *obj)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type, sizeof(struct nft_trans_obj));
        if (trans == NULL)
                return -ENOMEM;

        if (msg_type == NFT_MSG_NEWOBJ)
                nft_activate_next(ctx->net, obj);

        nft_trans_obj(trans) = obj;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);

        return 0;
}

static int nft_delobj(struct nft_ctx *ctx, struct nft_object *obj)
{
        int err;

        err = nft_trans_obj_add(ctx, NFT_MSG_DELOBJ, obj);
        if (err < 0)
                return err;

        nft_deactivate_next(ctx->net, obj);
        ctx->table->use--;

        return err;
}

static int nft_trans_flowtable_add(struct nft_ctx *ctx, int msg_type,
                                   struct nft_flowtable *flowtable)
{
        struct nft_trans *trans;

        trans = nft_trans_alloc(ctx, msg_type,
                                sizeof(struct nft_trans_flowtable));
        if (trans == NULL)
                return -ENOMEM;

        if (msg_type == NFT_MSG_NEWFLOWTABLE)
                nft_activate_next(ctx->net, flowtable);

        nft_trans_flowtable(trans) = flowtable;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);

        return 0;
}

static int nft_delflowtable(struct nft_ctx *ctx,
                            struct nft_flowtable *flowtable)
{
        int err;

        err = nft_trans_flowtable_add(ctx, NFT_MSG_DELFLOWTABLE, flowtable);
        if (err < 0)
                return err;

        nft_deactivate_next(ctx->net, flowtable);
        ctx->table->use--;

        return err;
}

/*
 * Tables
 */

static struct nft_table *nft_table_lookup(const struct net *net,
                                          const struct nlattr *nla,
                                          u8 family, u8 genmask)
{
        struct nft_table *table;

        if (nla == NULL)
                return ERR_PTR(-EINVAL);

        list_for_each_entry_rcu(table, &net->nft.tables, list,
                                lockdep_is_held(&net->nft.commit_mutex)) {
                if (!nla_strcmp(nla, table->name) &&
                    table->family == family &&
                    nft_active_genmask(table, genmask))
                        return table;
        }

        return ERR_PTR(-ENOENT);
}

static struct nft_table *nft_table_lookup_byhandle(const struct net *net,
                                                   const struct nlattr *nla,
                                                   u8 genmask)
{
        struct nft_table *table;

        list_for_each_entry(table, &net->nft.tables, list) {
                if (be64_to_cpu(nla_get_be64(nla)) == table->handle &&
                    nft_active_genmask(table, genmask))
                        return table;
        }

        return ERR_PTR(-ENOENT);
}

static inline u64 nf_tables_alloc_handle(struct nft_table *table)
{
        return ++table->hgenerator;
}

static const struct nft_chain_type *chain_type[NFPROTO_NUMPROTO][NFT_CHAIN_T_MAX];

static const struct nft_chain_type *
__nft_chain_type_get(u8 family, enum nft_chain_types type)
{
        if (family >= NFPROTO_NUMPROTO ||
            type >= NFT_CHAIN_T_MAX)
                return NULL;

        return chain_type[family][type];
}

static const struct nft_chain_type *
__nf_tables_chain_type_lookup(const struct nlattr *nla, u8 family)
{
        const struct nft_chain_type *type;
        int i;

        for (i = 0; i < NFT_CHAIN_T_MAX; i++) {
                type = __nft_chain_type_get(family, i);
                if (!type)
                        continue;
                if (!nla_strcmp(nla, type->name))
                        return type;
        }
        return NULL;
}

struct nft_module_request {
        struct list_head        list;
        char                    module[MODULE_NAME_LEN];
        bool                    done;
};

#ifdef CONFIG_MODULES
static int nft_request_module(struct net *net, const char *fmt, ...)
{
        char module_name[MODULE_NAME_LEN];
        struct nft_module_request *req;
        va_list args;
        int ret;

        va_start(args, fmt);
        ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
        va_end(args);
        if (ret >= MODULE_NAME_LEN)
                return 0;

        list_for_each_entry(req, &net->nft.module_list, list) {
                if (!strcmp(req->module, module_name)) {
                        if (req->done)
                                return 0;

                        /* A request to load this module already exists. */
                        return -EAGAIN;
                }
        }

        req = kmalloc(sizeof(*req), GFP_KERNEL);
        if (!req)
                return -ENOMEM;

        req->done = false;
        strlcpy(req->module, module_name, MODULE_NAME_LEN);
        list_add_tail(&req->list, &net->nft.module_list);

        return -EAGAIN;
}
#endif

static void lockdep_nfnl_nft_mutex_not_held(void)
{
#ifdef CONFIG_PROVE_LOCKING
        if (debug_locks)
                WARN_ON_ONCE(lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));
#endif
}

static const struct nft_chain_type *
nf_tables_chain_type_lookup(struct net *net, const struct nlattr *nla,
                            u8 family, bool autoload)
{
        const struct nft_chain_type *type;

        type = __nf_tables_chain_type_lookup(nla, family);
        if (type != NULL)
                return type;

        lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
        if (autoload) {
                if (nft_request_module(net, "nft-chain-%u-%.*s", family,
                                       nla_len(nla),
                                       (const char *)nla_data(nla)) == -EAGAIN)
                        return ERR_PTR(-EAGAIN);
        }
#endif
        return ERR_PTR(-ENOENT);
}

static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
        [NFTA_TABLE_NAME]       = { .type = NLA_STRING,
                                    .len = NFT_TABLE_MAXNAMELEN - 1 },
        [NFTA_TABLE_FLAGS]      = { .type = NLA_U32 },
        [NFTA_TABLE_HANDLE]     = { .type = NLA_U64 },
        [NFTA_TABLE_USERDATA]   = { .type = NLA_BINARY,
                                    .len = NFT_USERDATA_MAXLEN }
};

static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
                                     u32 portid, u32 seq, int event, u32 flags,
                                     int family, const struct nft_table *table)
{
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;

        event = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, event);
        nlh = nlmsg_put(skb, portid, seq, event, sizeof(struct nfgenmsg), flags);
        if (nlh == NULL)
                goto nla_put_failure;

        nfmsg = nlmsg_data(nlh);
        nfmsg->nfgen_family     = family;
        nfmsg->version          = NFNETLINK_V0;
        nfmsg->res_id           = htons(net->nft.base_seq & 0xffff);

        if (nla_put_string(skb, NFTA_TABLE_NAME, table->name) ||
            nla_put_be32(skb, NFTA_TABLE_FLAGS, htonl(table->flags)) ||
            nla_put_be32(skb, NFTA_TABLE_USE, htonl(table->use)) ||
            nla_put_be64(skb, NFTA_TABLE_HANDLE, cpu_to_be64(table->handle),
                         NFTA_TABLE_PAD))
                goto nla_put_failure;

        if (table->udata) {
                if (nla_put(skb, NFTA_TABLE_USERDATA, table->udlen, table->udata))
                        goto nla_put_failure;
        }

        nlmsg_end(skb, nlh);
        return 0;

nla_put_failure:
        nlmsg_trim(skb, nlh);
        return -1;
}

struct nftnl_skb_parms {
        bool report;
};
#define NFT_CB(skb)     (*(struct nftnl_skb_parms*)&((skb)->cb))

static void nft_notify_enqueue(struct sk_buff *skb, bool report,
                               struct list_head *notify_list)
{
        NFT_CB(skb).report = report;
        list_add_tail(&skb->list, notify_list);
}

static void nf_tables_table_notify(const struct nft_ctx *ctx, int event)
{
        struct sk_buff *skb;
        int err;
        char *buf = kasprintf(GFP_KERNEL, "%s:%llu;?:0",
                              ctx->table->name, ctx->table->handle);

        audit_log_nfcfg(buf,
                        ctx->family,
                        ctx->table->use,
                        event == NFT_MSG_NEWTABLE ?
                                AUDIT_NFT_OP_TABLE_REGISTER :
                                AUDIT_NFT_OP_TABLE_UNREGISTER,
                        GFP_KERNEL);
        kfree(buf);

        if (!ctx->report &&
            !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
                return;

        skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
        if (skb == NULL)
                goto err;

        err = nf_tables_fill_table_info(skb, ctx->net, ctx->portid, ctx->seq,
                                        event, 0, ctx->family, ctx->table);
        if (err < 0) {
                kfree_skb(skb);
                goto err;
        }

        nft_notify_enqueue(skb, ctx->report, &ctx->net->nft.notify_list);
        return;
err:
        nfnetlink_set_err(ctx->net, ctx->portid, NFNLGRP_NFTABLES, -ENOBUFS);
}

static int nf_tables_dump_tables(struct sk_buff *skb,
                                 struct netlink_callback *cb)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
        const struct nft_table *table;
        unsigned int idx = 0, s_idx = cb->args[0];
        struct net *net = sock_net(skb->sk);
        int family = nfmsg->nfgen_family;

        rcu_read_lock();
        cb->seq = net->nft.base_seq;

        list_for_each_entry_rcu(table, &net->nft.tables, list) {
                if (family != NFPROTO_UNSPEC && family != table->family)
                        continue;

                if (idx < s_idx)
                        goto cont;
                if (idx > s_idx)
                        memset(&cb->args[1], 0,
                               sizeof(cb->args) - sizeof(cb->args[0]));
                if (!nft_is_active(net, table))
                        continue;
                if (nf_tables_fill_table_info(skb, net,
                                              NETLINK_CB(cb->skb).portid,
                                              cb->nlh->nlmsg_seq,
                                              NFT_MSG_NEWTABLE, NLM_F_MULTI,
                                              table->family, table) < 0)
                        goto done;

                nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
                idx++;
        }
done:
        rcu_read_unlock();
        cb->args[0] = idx;
        return skb->len;
}

static int nft_netlink_dump_start_rcu(struct sock *nlsk, struct sk_buff *skb,
                                      const struct nlmsghdr *nlh,
                                      struct netlink_dump_control *c)
{
        int err;

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

        rcu_read_unlock();
        err = netlink_dump_start(nlsk, skb, nlh, c);
        rcu_read_lock();
        module_put(THIS_MODULE);

        return err;
}

/* called with rcu_read_lock held */
static int nf_tables_gettable(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_cur(net);
        const struct nft_table *table;
        struct sk_buff *skb2;
        int family = nfmsg->nfgen_family;
        int err;

        if (nlh->nlmsg_flags & NLM_F_DUMP) {
                struct netlink_dump_control c = {
                        .dump = nf_tables_dump_tables,
                        .module = THIS_MODULE,
                };

                return nft_netlink_dump_start_rcu(nlsk, skb, nlh, &c);
        }

        table = nft_table_lookup(net, nla[NFTA_TABLE_NAME], family, genmask);
        if (IS_ERR(table)) {
                NL_SET_BAD_ATTR(extack, nla[NFTA_TABLE_NAME]);
                return PTR_ERR(table);
        }

        skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
        if (!skb2)
                return -ENOMEM;

        err = nf_tables_fill_table_info(skb2, net, NETLINK_CB(skb).portid,
                                        nlh->nlmsg_seq, NFT_MSG_NEWTABLE, 0,
                                        family, table);
        if (err < 0)
                goto err_fill_table_info;

        return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);

err_fill_table_info:
        kfree_skb(skb2);
        return err;
}

static void nft_table_disable(struct net *net, struct nft_table *table, u32 cnt)
{
        struct nft_chain *chain;
        u32 i = 0;

        list_for_each_entry(chain, &table->chains, list) {
                if (!nft_is_active_next(net, chain))
                        continue;
                if (!nft_is_base_chain(chain))
                        continue;

                if (cnt && i++ == cnt)
                        break;

                nf_tables_unregister_hook(net, table, chain);
        }
}

static int nf_tables_table_enable(struct net *net, struct nft_table *table)
{
        struct nft_chain *chain;
        int err, i = 0;

        list_for_each_entry(chain, &table->chains, list) {
                if (!nft_is_active_next(net, chain))
                        continue;
                if (!nft_is_base_chain(chain))
                        continue;

                err = nf_tables_register_hook(net, table, chain);
                if (err < 0)
                        goto err_register_hooks;

                i++;
        }
        return 0;

err_register_hooks:
        if (i)
                nft_table_disable(net, table, i);
        return err;
}

static void nf_tables_table_disable(struct net *net, struct nft_table *table)
{
        nft_table_disable(net, table, 0);
}

static int nf_tables_updtable(struct nft_ctx *ctx)
{
        struct nft_trans *trans;
        u32 flags;
        int ret = 0;

        if (!ctx->nla[NFTA_TABLE_FLAGS])
                return 0;

        flags = ntohl(nla_get_be32(ctx->nla[NFTA_TABLE_FLAGS]));
        if (flags & ~NFT_TABLE_F_DORMANT)
                return -EINVAL;

        if (flags == ctx->table->flags)
                return 0;

        trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
                                sizeof(struct nft_trans_table));
        if (trans == NULL)
                return -ENOMEM;

        if ((flags & NFT_TABLE_F_DORMANT) &&
            !(ctx->table->flags & NFT_TABLE_F_DORMANT)) {
                nft_trans_table_enable(trans) = false;
        } else if (!(flags & NFT_TABLE_F_DORMANT) &&
                   ctx->table->flags & NFT_TABLE_F_DORMANT) {
                ctx->table->flags &= ~NFT_TABLE_F_DORMANT;
                ret = nf_tables_table_enable(ctx->net, ctx->table);
                if (ret >= 0)
                        nft_trans_table_enable(trans) = true;
                else
                        ctx->table->flags |= NFT_TABLE_F_DORMANT;
        }
        if (ret < 0)
                goto err;

        nft_trans_table_update(trans) = true;
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);
        return 0;
err:
        nft_trans_destroy(trans);
        return ret;
}

static u32 nft_chain_hash(const void *data, u32 len, u32 seed)
{
        const char *name = data;

        return jhash(name, strlen(name), seed);
}

static u32 nft_chain_hash_obj(const void *data, u32 len, u32 seed)
{
        const struct nft_chain *chain = data;

        return nft_chain_hash(chain->name, 0, seed);
}

static int nft_chain_hash_cmp(struct rhashtable_compare_arg *arg,
                              const void *ptr)
{
        const struct nft_chain *chain = ptr;
        const char *name = arg->key;

        return strcmp(chain->name, name);
}

static u32 nft_objname_hash(const void *data, u32 len, u32 seed)
{
        const struct nft_object_hash_key *k = data;

        seed ^= hash_ptr(k->table, 32);

        return jhash(k->name, strlen(k->name), seed);
}

static u32 nft_objname_hash_obj(const void *data, u32 len, u32 seed)
{
        const struct nft_object *obj = data;

        return nft_objname_hash(&obj->key, 0, seed);
}

static int nft_objname_hash_cmp(struct rhashtable_compare_arg *arg,
                                const void *ptr)
{
        const struct nft_object_hash_key *k = arg->key;
        const struct nft_object *obj = ptr;

        if (obj->key.table != k->table)
                return -1;

        return strcmp(obj->key.name, k->name);
}

static int nf_tables_newtable(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_next(net);
        int family = nfmsg->nfgen_family;
        const struct nlattr *attr;
        struct nft_table *table;
        struct nft_ctx ctx;
        u32 flags = 0;

        int err;

        lockdep_assert_held(&net->nft.commit_mutex);
        attr = nla[NFTA_TABLE_NAME];
        table = nft_table_lookup(net, attr, family, genmask);
        if (IS_ERR(table)) {
                if (PTR_ERR(table) != -ENOENT)
                        return PTR_ERR(table);
        } else {
                if (nlh->nlmsg_flags & NLM_F_EXCL) {
                        NL_SET_BAD_ATTR(extack, attr);
                        return -EEXIST;
                }
                if (nlh->nlmsg_flags & NLM_F_REPLACE)
                        return -EOPNOTSUPP;

                nft_ctx_init(&ctx, net, skb, nlh, family, table, NULL, nla);
                return nf_tables_updtable(&ctx);
        }

        if (nla[NFTA_TABLE_FLAGS]) {
                flags = ntohl(nla_get_be32(nla[NFTA_TABLE_FLAGS]));
                if (flags & ~NFT_TABLE_F_DORMANT)
                        return -EINVAL;
        }

        err = -ENOMEM;
        table = kzalloc(sizeof(*table), GFP_KERNEL);
        if (table == NULL)
                goto err_kzalloc;

        table->name = nla_strdup(attr, GFP_KERNEL);
        if (table->name == NULL)
                goto err_strdup;

        if (nla[NFTA_TABLE_USERDATA]) {
                table->udata = nla_memdup(nla[NFTA_TABLE_USERDATA], GFP_KERNEL);
                if (table->udata == NULL)
                        goto err_table_udata;

                table->udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
        }

        err = rhltable_init(&table->chains_ht, &nft_chain_ht_params);
        if (err)
                goto err_chain_ht;

        INIT_LIST_HEAD(&table->chains);
        INIT_LIST_HEAD(&table->sets);
        INIT_LIST_HEAD(&table->objects);
        INIT_LIST_HEAD(&table->flowtables);
        table->family = family;
        table->flags = flags;
        table->handle = ++table_handle;

        nft_ctx_init(&ctx, net, skb, nlh, family, table, NULL, nla);
        err = nft_trans_table_add(&ctx, NFT_MSG_NEWTABLE);
        if (err < 0)
                goto err_trans;

        list_add_tail_rcu(&table->list, &net->nft.tables);
        return 0;
err_trans:
        rhltable_destroy(&table->chains_ht);
err_chain_ht:
        kfree(table->udata);
err_table_udata:
        kfree(table->name);
err_strdup:
        kfree(table);
err_kzalloc:
        return err;
}

static int nft_flush_table(struct nft_ctx *ctx)
{
        struct nft_flowtable *flowtable, *nft;
        struct nft_chain *chain, *nc;
        struct nft_object *obj, *ne;
        struct nft_set *set, *ns;
        int err;

        list_for_each_entry(chain, &ctx->table->chains, list) {
                if (!nft_is_active_next(ctx->net, chain))
                        continue;

                if (nft_chain_is_bound(chain))
                        continue;

                ctx->chain = chain;

                err = nft_delrule_by_chain(ctx);
                if (err < 0)
                        goto out;
        }

        list_for_each_entry_safe(set, ns, &ctx->table->sets, list) {
                if (!nft_is_active_next(ctx->net, set))
                        continue;

                if (nft_set_is_anonymous(set) &&
                    !list_empty(&set->bindings))
                        continue;

                err = nft_delset(ctx, set);
                if (err < 0)
                        goto out;
        }

        list_for_each_entry_safe(flowtable, nft, &ctx->table->flowtables, list) {
                if (!nft_is_active_next(ctx->net, flowtable))
                        continue;

                err = nft_delflowtable(ctx, flowtable);
                if (err < 0)
                        goto out;
        }

        list_for_each_entry_safe(obj, ne, &ctx->table->objects, list) {
                if (!nft_is_active_next(ctx->net, obj))
                        continue;

                err = nft_delobj(ctx, obj);
                if (err < 0)
                        goto out;
        }

        list_for_each_entry_safe(chain, nc, &ctx->table->chains, list) {
                if (!nft_is_active_next(ctx->net, chain))
                        continue;

                if (nft_chain_is_bound(chain))
                        continue;

                ctx->chain = chain;

                err = nft_delchain(ctx);
                if (err < 0)
                        goto out;
        }

        err = nft_deltable(ctx);
out:
        return err;
}

static int nft_flush(struct nft_ctx *ctx, int family)
{
        struct nft_table *table, *nt;
        const struct nlattr * const *nla = ctx->nla;
        int err = 0;

        list_for_each_entry_safe(table, nt, &ctx->net->nft.tables, list) {
                if (family != AF_UNSPEC && table->family != family)
                        continue;

                ctx->family = table->family;

                if (!nft_is_active_next(ctx->net, table))
                        continue;

                if (nla[NFTA_TABLE_NAME] &&
                    nla_strcmp(nla[NFTA_TABLE_NAME], table->name) != 0)
                        continue;

                ctx->table = table;

                err = nft_flush_table(ctx);
                if (err < 0)
                        goto out;
        }
out:
        return err;
}

static int nf_tables_deltable(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_next(net);
        int family = nfmsg->nfgen_family;
        const struct nlattr *attr;
        struct nft_table *table;
        struct nft_ctx ctx;

        nft_ctx_init(&ctx, net, skb, nlh, 0, NULL, NULL, nla);
        if (family == AF_UNSPEC ||
            (!nla[NFTA_TABLE_NAME] && !nla[NFTA_TABLE_HANDLE]))
                return nft_flush(&ctx, family);

        if (nla[NFTA_TABLE_HANDLE]) {
                attr = nla[NFTA_TABLE_HANDLE];
                table = nft_table_lookup_byhandle(net, attr, genmask);
        } else {
                attr = nla[NFTA_TABLE_NAME];
                table = nft_table_lookup(net, attr, family, genmask);
        }

        if (IS_ERR(table)) {
                NL_SET_BAD_ATTR(extack, attr);
                return PTR_ERR(table);
        }

        if (nlh->nlmsg_flags & NLM_F_NONREC &&
            table->use > 0)
                return -EBUSY;

        ctx.family = family;
        ctx.table = table;

        return nft_flush_table(&ctx);
}

static void nf_tables_table_destroy(struct nft_ctx *ctx)
{
        if (WARN_ON(ctx->table->use > 0))
                return;

        rhltable_destroy(&ctx->table->chains_ht);
        kfree(ctx->table->name);
        kfree(ctx->table->udata);
        kfree(ctx->table);
}

void nft_register_chain_type(const struct nft_chain_type *ctype)
{
        nfnl_lock(NFNL_SUBSYS_NFTABLES);
        if (WARN_ON(__nft_chain_type_get(ctype->family, ctype->type))) {
                nfnl_unlock(NFNL_SUBSYS_NFTABLES);
                return;
        }
        chain_type[ctype->family][ctype->type] = ctype;
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
}
EXPORT_SYMBOL_GPL(nft_register_chain_type);

void nft_unregister_chain_type(const struct nft_chain_type *ctype)
{
        nfnl_lock(NFNL_SUBSYS_NFTABLES);
        chain_type[ctype->family][ctype->type] = NULL;
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
}
EXPORT_SYMBOL_GPL(nft_unregister_chain_type);

/*
 * Chains
 */

static struct nft_chain *
nft_chain_lookup_byhandle(const struct nft_table *table, u64 handle, u8 genmask)
{
        struct nft_chain *chain;

        list_for_each_entry(chain, &table->chains, list) {
                if (chain->handle == handle &&
                    nft_active_genmask(chain, genmask))
                        return chain;
        }

        return ERR_PTR(-ENOENT);
}

static bool lockdep_commit_lock_is_held(const struct net *net)
{
#ifdef CONFIG_PROVE_LOCKING
        return lockdep_is_held(&net->nft.commit_mutex);
#else
        return true;
#endif
}

static struct nft_chain *nft_chain_lookup(struct net *net,
                                          struct nft_table *table,
                                          const struct nlattr *nla, u8 genmask)
{
        char search[NFT_CHAIN_MAXNAMELEN + 1];
        struct rhlist_head *tmp, *list;
        struct nft_chain *chain;

        if (nla == NULL)
                return ERR_PTR(-EINVAL);

        nla_strlcpy(search, nla, sizeof(search));

        WARN_ON(!rcu_read_lock_held() &&
                !lockdep_commit_lock_is_held(net));

        chain = ERR_PTR(-ENOENT);
        rcu_read_lock();
        list = rhltable_lookup(&table->chains_ht, search, nft_chain_ht_params);
        if (!list)
                goto out_unlock;

        rhl_for_each_entry_rcu(chain, tmp, list, rhlhead) {
                if (nft_active_genmask(chain, genmask))
                        goto out_unlock;
        }
        chain = ERR_PTR(-ENOENT);
out_unlock:
        rcu_read_unlock();
        return chain;
}

static const struct nla_policy nft_chain_policy[NFTA_CHAIN_MAX + 1] = {
        [NFTA_CHAIN_TABLE]      = { .type = NLA_STRING,
                                    .len = NFT_TABLE_MAXNAMELEN - 1 },
        [NFTA_CHAIN_HANDLE]     = { .type = NLA_U64 },
        [NFTA_CHAIN_NAME]       = { .type = NLA_STRING,
                                    .len = NFT_CHAIN_MAXNAMELEN - 1 },
        [NFTA_CHAIN_HOOK]       = { .type = NLA_NESTED },
        [NFTA_CHAIN_POLICY]     = { .type = NLA_U32 },
        [NFTA_CHAIN_TYPE]       = { .type = NLA_STRING,
                                    .len = NFT_MODULE_AUTOLOAD_LIMIT },
        [NFTA_CHAIN_COUNTERS]   = { .type = NLA_NESTED },
        [NFTA_CHAIN_FLAGS]      = { .type = NLA_U32 },
        [NFTA_CHAIN_ID]         = { .type = NLA_U32 },
        [NFTA_CHAIN_USERDATA]   = { .type = NLA_BINARY,
                                    .len = NFT_USERDATA_MAXLEN },
};

static const struct nla_policy nft_hook_policy[NFTA_HOOK_MAX + 1] = {
        [NFTA_HOOK_HOOKNUM]     = { .type = NLA_U32 },
        [NFTA_HOOK_PRIORITY]    = { .type = NLA_U32 },
        [NFTA_HOOK_DEV]         = { .type = NLA_STRING,
                                    .len = IFNAMSIZ - 1 },
};

static int nft_dump_stats(struct sk_buff *skb, struct nft_stats __percpu *stats)
{
        struct nft_stats *cpu_stats, total;
        struct nlattr *nest;
        unsigned int seq;
        u64 pkts, bytes;
        int cpu;

        if (!stats)
                return 0;

        memset(&total, 0, sizeof(total));
        for_each_possible_cpu(cpu) {
                cpu_stats = per_cpu_ptr(stats, cpu);
                do {
                        seq = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
                        pkts = cpu_stats->pkts;
                        bytes = cpu_stats->bytes;
                } while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, seq));
                total.pkts += pkts;
                total.bytes += bytes;
        }
        nest = nla_nest_start_noflag(skb, NFTA_CHAIN_COUNTERS);
        if (nest == NULL)
                goto nla_put_failure;

        if (nla_put_be64(skb, NFTA_COUNTER_PACKETS, cpu_to_be64(total.pkts),
                         NFTA_COUNTER_PAD) ||
            nla_put_be64(skb, NFTA_COUNTER_BYTES, cpu_to_be64(total.bytes),
                         NFTA_COUNTER_PAD))
                goto nla_put_failure;

        nla_nest_end(skb, nest);
        return 0;

nla_put_failure:
        return -ENOSPC;
}

static int nft_dump_basechain_hook(struct sk_buff *skb, int family,
                                   const struct nft_base_chain *basechain)
{
        const struct nf_hook_ops *ops = &basechain->ops;
        struct nft_hook *hook, *first = NULL;
        struct nlattr *nest, *nest_devs;
        int n = 0;

        nest = nla_nest_start_noflag(skb, NFTA_CHAIN_HOOK);
        if (nest == NULL)
                goto nla_put_failure;
        if (nla_put_be32(skb, NFTA_HOOK_HOOKNUM, htonl(ops->hooknum)))
                goto nla_put_failure;
        if (nla_put_be32(skb, NFTA_HOOK_PRIORITY, htonl(ops->priority)))
                goto nla_put_failure;

        if (nft_base_chain_netdev(family, ops->hooknum)) {
                nest_devs = nla_nest_start_noflag(skb, NFTA_HOOK_DEVS);
                list_for_each_entry(hook, &basechain->hook_list, list) {
                        if (!first)
                                first = hook;

                        if (nla_put_string(skb, NFTA_DEVICE_NAME,
                                           hook->ops.dev->name))
                                goto nla_put_failure;
                        n++;
                }
                nla_nest_end(skb, nest_devs);

                if (n == 1 &&
                    nla_put_string(skb, NFTA_HOOK_DEV, first->ops.dev->name))
                        goto nla_put_failure;
        }
        nla_nest_end(skb, nest);

        return 0;
nla_put_failure:
        return -1;
}

static int nf_tables_fill_chain_info(struct sk_buff *skb, struct net *net,
                                     u32 portid, u32 seq, int event, u32 flags,
                                     int family, const struct nft_table *table,
                                     const struct nft_chain *chain)
{
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;

        event = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, event);
        nlh = nlmsg_put(skb, portid, seq, event, sizeof(struct nfgenmsg), flags);
        if (nlh == NULL)
                goto nla_put_failure;

        nfmsg = nlmsg_data(nlh);
        nfmsg->nfgen_family     = family;
        nfmsg->version          = NFNETLINK_V0;
        nfmsg->res_id           = htons(net->nft.base_seq & 0xffff);

        if (nla_put_string(skb, NFTA_CHAIN_TABLE, table->name))
                goto nla_put_failure;
        if (nla_put_be64(skb, NFTA_CHAIN_HANDLE, cpu_to_be64(chain->handle),
                         NFTA_CHAIN_PAD))
                goto nla_put_failure;
        if (nla_put_string(skb, NFTA_CHAIN_NAME, chain->name))
                goto nla_put_failure;

        if (nft_is_base_chain(chain)) {
                const struct nft_base_chain *basechain = nft_base_chain(chain);
                struct nft_stats __percpu *stats;

                if (nft_dump_basechain_hook(skb, family, basechain))
                        goto nla_put_failure;

                if (nla_put_be32(skb, NFTA_CHAIN_POLICY,
                                 htonl(basechain->policy)))
                        goto nla_put_failure;

                if (nla_put_string(skb, NFTA_CHAIN_TYPE, basechain->type->name))
                        goto nla_put_failure;

                stats = rcu_dereference_check(basechain->stats,
                                              lockdep_commit_lock_is_held(net));
                if (nft_dump_stats(skb, stats))
                        goto nla_put_failure;
        }

        if (chain->flags &&
            nla_put_be32(skb, NFTA_CHAIN_FLAGS, htonl(chain->flags)))
                goto nla_put_failure;

        if (nla_put_be32(skb, NFTA_CHAIN_USE, htonl(chain->use)))
                goto nla_put_failure;

        if (chain->udata &&
            nla_put(skb, NFTA_CHAIN_USERDATA, chain->udlen, chain->udata))
                goto nla_put_failure;

        nlmsg_end(skb, nlh);
        return 0;

nla_put_failure:
        nlmsg_trim(skb, nlh);
        return -1;
}

static void nf_tables_chain_notify(const struct nft_ctx *ctx, int event)
{
        struct sk_buff *skb;
        int err;
        char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
                              ctx->table->name, ctx->table->handle,
                              ctx->chain->name, ctx->chain->handle);

        audit_log_nfcfg(buf,
                        ctx->family,
                        ctx->chain->use,
                        event == NFT_MSG_NEWCHAIN ?
                                AUDIT_NFT_OP_CHAIN_REGISTER :
                                AUDIT_NFT_OP_CHAIN_UNREGISTER,
                        GFP_KERNEL);
        kfree(buf);

        if (!ctx->report &&
            !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
                return;

        skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
        if (skb == NULL)
                goto err;

        err = nf_tables_fill_chain_info(skb, ctx->net, ctx->portid, ctx->seq,
                                        event, 0, ctx->family, ctx->table,
                                        ctx->chain);
        if (err < 0) {
                kfree_skb(skb);
                goto err;
        }

        nft_notify_enqueue(skb, ctx->report, &ctx->net->nft.notify_list);
        return;
err:
        nfnetlink_set_err(ctx->net, ctx->portid, NFNLGRP_NFTABLES, -ENOBUFS);
}

static int nf_tables_dump_chains(struct sk_buff *skb,
                                 struct netlink_callback *cb)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
        const struct nft_table *table;
        const struct nft_chain *chain;
        unsigned int idx = 0, s_idx = cb->args[0];
        struct net *net = sock_net(skb->sk);
        int family = nfmsg->nfgen_family;

        rcu_read_lock();
        cb->seq = net->nft.base_seq;

        list_for_each_entry_rcu(table, &net->nft.tables, list) {
                if (family != NFPROTO_UNSPEC && family != table->family)
                        continue;

                list_for_each_entry_rcu(chain, &table->chains, list) {
                        if (idx < s_idx)
                                goto cont;
                        if (idx > s_idx)
                                memset(&cb->args[1], 0,
                                       sizeof(cb->args) - sizeof(cb->args[0]));
                        if (!nft_is_active(net, chain))
                                continue;
                        if (nf_tables_fill_chain_info(skb, net,
                                                      NETLINK_CB(cb->skb).portid,
                                                      cb->nlh->nlmsg_seq,
                                                      NFT_MSG_NEWCHAIN,
                                                      NLM_F_MULTI,
                                                      table->family, table,
                                                      chain) < 0)
                                goto done;

                        nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
                        idx++;
                }
        }
done:
        rcu_read_unlock();
        cb->args[0] = idx;
        return skb->len;
}

/* called with rcu_read_lock held */
static int nf_tables_getchain(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_cur(net);
        const struct nft_chain *chain;
        struct nft_table *table;
        struct sk_buff *skb2;
        int family = nfmsg->nfgen_family;
        int err;

        if (nlh->nlmsg_flags & NLM_F_DUMP) {
                struct netlink_dump_control c = {
                        .dump = nf_tables_dump_chains,
                        .module = THIS_MODULE,
                };

                return nft_netlink_dump_start_rcu(nlsk, skb, nlh, &c);
        }

        table = nft_table_lookup(net, nla[NFTA_CHAIN_TABLE], family, genmask);
        if (IS_ERR(table)) {
                NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_TABLE]);
                return PTR_ERR(table);
        }

        chain = nft_chain_lookup(net, table, nla[NFTA_CHAIN_NAME], genmask);
        if (IS_ERR(chain)) {
                NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_NAME]);
                return PTR_ERR(chain);
        }

        skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
        if (!skb2)
                return -ENOMEM;

        err = nf_tables_fill_chain_info(skb2, net, NETLINK_CB(skb).portid,
                                        nlh->nlmsg_seq, NFT_MSG_NEWCHAIN, 0,
                                        family, table, chain);
        if (err < 0)
                goto err_fill_chain_info;

        return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);

err_fill_chain_info:
        kfree_skb(skb2);
        return err;
}

static const struct nla_policy nft_counter_policy[NFTA_COUNTER_MAX + 1] = {
        [NFTA_COUNTER_PACKETS]  = { .type = NLA_U64 },
        [NFTA_COUNTER_BYTES]    = { .type = NLA_U64 },
};

static struct nft_stats __percpu *nft_stats_alloc(const struct nlattr *attr)
{
        struct nlattr *tb[NFTA_COUNTER_MAX+1];
        struct nft_stats __percpu *newstats;
        struct nft_stats *stats;
        int err;

        err = nla_parse_nested_deprecated(tb, NFTA_COUNTER_MAX, attr,
                                          nft_counter_policy, NULL);
        if (err < 0)
                return ERR_PTR(err);

        if (!tb[NFTA_COUNTER_BYTES] || !tb[NFTA_COUNTER_PACKETS])
                return ERR_PTR(-EINVAL);

        newstats = netdev_alloc_pcpu_stats(struct nft_stats);
        if (newstats == NULL)
                return ERR_PTR(-ENOMEM);

        /* Restore old counters on this cpu, no problem. Per-cpu statistics
         * are not exposed to userspace.
         */
        preempt_disable();
        stats = this_cpu_ptr(newstats);
        stats->bytes = be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_BYTES]));
        stats->pkts = be64_to_cpu(nla_get_be64(tb[NFTA_COUNTER_PACKETS]));
        preempt_enable();

        return newstats;
}

static void nft_chain_stats_replace(struct nft_trans *trans)
{
        struct nft_base_chain *chain = nft_base_chain(trans->ctx.chain);

        if (!nft_trans_chain_stats(trans))
                return;

        nft_trans_chain_stats(trans) =
                rcu_replace_pointer(chain->stats, nft_trans_chain_stats(trans),
                                    lockdep_commit_lock_is_held(trans->ctx.net));

        if (!nft_trans_chain_stats(trans))
                static_branch_inc(&nft_counters_enabled);
}

static void nf_tables_chain_free_chain_rules(struct nft_chain *chain)
{
        struct nft_rule **g0 = rcu_dereference_raw(chain->rules_gen_0);
        struct nft_rule **g1 = rcu_dereference_raw(chain->rules_gen_1);

        if (g0 != g1)
                kvfree(g1);
        kvfree(g0);

        /* should be NULL either via abort or via successful commit */
        WARN_ON_ONCE(chain->rules_next);
        kvfree(chain->rules_next);
}

void nf_tables_chain_destroy(struct nft_ctx *ctx)
{
        struct nft_chain *chain = ctx->chain;
        struct nft_hook *hook, *next;

        if (WARN_ON(chain->use > 0))
                return;

        /* no concurrent access possible anymore */
        nf_tables_chain_free_chain_rules(chain);

        if (nft_is_base_chain(chain)) {
                struct nft_base_chain *basechain = nft_base_chain(chain);

                if (nft_base_chain_netdev(ctx->family, basechain->ops.hooknum)) {
                        list_for_each_entry_safe(hook, next,
                                                 &basechain->hook_list, list) {
                                list_del_rcu(&hook->list);
                                kfree_rcu(hook, rcu);
                        }
                }
                module_put(basechain->type->owner);
                if (rcu_access_pointer(basechain->stats)) {
                        static_branch_dec(&nft_counters_enabled);
                        free_percpu(rcu_dereference_raw(basechain->stats));
                }
                kfree(chain->name);
                kfree(chain->udata);
                kfree(basechain);
        } else {
                kfree(chain->name);
                kfree(chain->udata);
                kfree(chain);
        }
}

static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
                                              const struct nlattr *attr)
{
        struct net_device *dev;
        char ifname[IFNAMSIZ];
        struct nft_hook *hook;
        int err;

        hook = kmalloc(sizeof(struct nft_hook), GFP_KERNEL);
        if (!hook) {
                err = -ENOMEM;
                goto err_hook_alloc;
        }

        nla_strlcpy(ifname, attr, IFNAMSIZ);
        /* nf_tables_netdev_event() is called under rtnl_mutex, this is
         * indirectly serializing all the other holders of the commit_mutex with
         * the rtnl_mutex.
         */
        dev = __dev_get_by_name(net, ifname);
        if (!dev) {
                err = -ENOENT;
                goto err_hook_dev;
        }
        hook->ops.dev = dev;
        hook->inactive = false;

        return hook;

err_hook_dev:
        kfree(hook);
err_hook_alloc:
        return ERR_PTR(err);
}

static struct nft_hook *nft_hook_list_find(struct list_head *hook_list,
                                           const struct nft_hook *this)
{
        struct nft_hook *hook;

        list_for_each_entry(hook, hook_list, list) {
                if (this->ops.dev == hook->ops.dev)
                        return hook;
        }

        return NULL;
}

static int nf_tables_parse_netdev_hooks(struct net *net,
                                        const struct nlattr *attr,
                                        struct list_head *hook_list)
{
        struct nft_hook *hook, *next;
        const struct nlattr *tmp;
        int rem, n = 0, err;

        nla_for_each_nested(tmp, attr, rem) {
                if (nla_type(tmp) != NFTA_DEVICE_NAME) {
                        err = -EINVAL;
                        goto err_hook;
                }

                hook = nft_netdev_hook_alloc(net, tmp);
                if (IS_ERR(hook)) {
                        err = PTR_ERR(hook);
                        goto err_hook;
                }
                if (nft_hook_list_find(hook_list, hook)) {
                        kfree(hook);
                        err = -EEXIST;
                        goto err_hook;
                }
                list_add_tail(&hook->list, hook_list);
                n++;

                if (n == NFT_NETDEVICE_MAX) {
                        err = -EFBIG;
                        goto err_hook;
                }
        }

        return 0;

err_hook:
        list_for_each_entry_safe(hook, next, hook_list, list) {
                list_del(&hook->list);
                kfree(hook);
        }
        return err;
}

struct nft_chain_hook {
        u32                             num;
        s32                             priority;
        const struct nft_chain_type     *type;
        struct list_head                list;
};

static int nft_chain_parse_netdev(struct net *net,
                                  struct nlattr *tb[],
                                  struct list_head *hook_list)
{
        struct nft_hook *hook;
        int err;

        if (tb[NFTA_HOOK_DEV]) {
                hook = nft_netdev_hook_alloc(net, tb[NFTA_HOOK_DEV]);
                if (IS_ERR(hook))
                        return PTR_ERR(hook);

                list_add_tail(&hook->list, hook_list);
        } else if (tb[NFTA_HOOK_DEVS]) {
                err = nf_tables_parse_netdev_hooks(net, tb[NFTA_HOOK_DEVS],
                                                   hook_list);
                if (err < 0)
                        return err;

                if (list_empty(hook_list))
                        return -EINVAL;
        } else {
                return -EINVAL;
        }

        return 0;
}

static int nft_chain_parse_hook(struct net *net,
                                const struct nlattr * const nla[],
                                struct nft_chain_hook *hook, u8 family,
                                bool autoload)
{
        struct nlattr *ha[NFTA_HOOK_MAX + 1];
        const struct nft_chain_type *type;
        int err;

        lockdep_assert_held(&net->nft.commit_mutex);
        lockdep_nfnl_nft_mutex_not_held();

        err = nla_parse_nested_deprecated(ha, NFTA_HOOK_MAX,
                                          nla[NFTA_CHAIN_HOOK],
                                          nft_hook_policy, NULL);
        if (err < 0)
                return err;

        if (ha[NFTA_HOOK_HOOKNUM] == NULL ||
            ha[NFTA_HOOK_PRIORITY] == NULL)
                return -EINVAL;

        hook->num = ntohl(nla_get_be32(ha[NFTA_HOOK_HOOKNUM]));
        hook->priority = ntohl(nla_get_be32(ha[NFTA_HOOK_PRIORITY]));

        type = __nft_chain_type_get(family, NFT_CHAIN_T_DEFAULT);
        if (!type)
                return -EOPNOTSUPP;

        if (nla[NFTA_CHAIN_TYPE]) {
                type = nf_tables_chain_type_lookup(net, nla[NFTA_CHAIN_TYPE],
                                                   family, autoload);
                if (IS_ERR(type))
                        return PTR_ERR(type);
        }
        if (hook->num >= NFT_MAX_HOOKS || !(type->hook_mask & (1 << hook->num)))
                return -EOPNOTSUPP;

        if (type->type == NFT_CHAIN_T_NAT &&
            hook->priority <= NF_IP_PRI_CONNTRACK)
                return -EOPNOTSUPP;

        if (!try_module_get(type->owner))
                return -ENOENT;

        hook->type = type;

        INIT_LIST_HEAD(&hook->list);
        if (nft_base_chain_netdev(family, hook->num)) {
                err = nft_chain_parse_netdev(net, ha, &hook->list);
                if (err < 0) {
                        module_put(type->owner);
                        return err;
                }
        } else if (ha[NFTA_HOOK_DEV] || ha[NFTA_HOOK_DEVS]) {
                module_put(type->owner);
                return -EOPNOTSUPP;
        }

        return 0;
}

static void nft_chain_release_hook(struct nft_chain_hook *hook)
{
        struct nft_hook *h, *next;

        list_for_each_entry_safe(h, next, &hook->list, list) {
                list_del(&h->list);
                kfree(h);
        }
        module_put(hook->type->owner);
}

struct nft_rules_old {
        struct rcu_head h;
        struct nft_rule **start;
};

static struct nft_rule **nf_tables_chain_alloc_rules(const struct nft_chain *chain,
                                                     unsigned int alloc)
{
        if (alloc > INT_MAX)
                return NULL;

        alloc += 1;     /* NULL, ends rules */
        if (sizeof(struct nft_rule *) > INT_MAX / alloc)
                return NULL;

        alloc *= sizeof(struct nft_rule *);
        alloc += sizeof(struct nft_rules_old);

        return kvmalloc(alloc, GFP_KERNEL);
}

static void nft_basechain_hook_init(struct nf_hook_ops *ops, u8 family,
                                    const struct nft_chain_hook *hook,
                                    struct nft_chain *chain)
{
        ops->pf         = family;
        ops->hooknum    = hook->num;
        ops->priority   = hook->priority;
        ops->priv       = chain;
        ops->hook       = hook->type->hooks[ops->hooknum];
}

static int nft_basechain_init(struct nft_base_chain *basechain, u8 family,
                              struct nft_chain_hook *hook, u32 flags)
{
        struct nft_chain *chain;
        struct nft_hook *h;

        basechain->type = hook->type;
        INIT_LIST_HEAD(&basechain->hook_list);
        chain = &basechain->chain;

        if (nft_base_chain_netdev(family, hook->num)) {
                list_splice_init(&hook->list, &basechain->hook_list);
                list_for_each_entry(h, &basechain->hook_list, list)
                        nft_basechain_hook_init(&h->ops, family, hook, chain);

                basechain->ops.hooknum  = hook->num;
                basechain->ops.priority = hook->priority;
        } else {
                nft_basechain_hook_init(&basechain->ops, family, hook, chain);
        }

        chain->flags |= NFT_CHAIN_BASE | flags;
        basechain->policy = NF_ACCEPT;
        if (chain->flags & NFT_CHAIN_HW_OFFLOAD &&
            nft_chain_offload_priority(basechain) < 0)
                return -EOPNOTSUPP;

        flow_block_init(&basechain->flow_block);

        return 0;
}

static int nft_chain_add(struct nft_table *table, struct nft_chain *chain)
{
        int err;

        err = rhltable_insert_key(&table->chains_ht, chain->name,
                                  &chain->rhlhead, nft_chain_ht_params);
        if (err)
                return err;

        list_add_tail_rcu(&chain->list, &table->chains);

        return 0;
}

static u64 chain_id;

static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
                              u8 policy, u32 flags)
{
        const struct nlattr * const *nla = ctx->nla;
        struct nft_table *table = ctx->table;
        struct nft_base_chain *basechain;
        struct nft_stats __percpu *stats;
        struct net *net = ctx->net;
        char name[NFT_NAME_MAXLEN];
        struct nft_trans *trans;
        struct nft_chain *chain;

        struct nft_rule **rules;
        int err;

        if (table->use == UINT_MAX)
                return -EOVERFLOW;

        if (nla[NFTA_CHAIN_HOOK]) {
                struct nft_chain_hook hook;

                if (flags & NFT_CHAIN_BINDING)
                        return -EOPNOTSUPP;

                err = nft_chain_parse_hook(net, nla, &hook, family, true);
                if (err < 0)
                        return err;

                basechain = kzalloc(sizeof(*basechain), GFP_KERNEL);
                if (basechain == NULL) {
                        nft_chain_release_hook(&hook);
                        return -ENOMEM;
                }
                chain = &basechain->chain;

                if (nla[NFTA_CHAIN_COUNTERS]) {
                        stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
                        if (IS_ERR(stats)) {
                                nft_chain_release_hook(&hook);
                                kfree(basechain);
                                return PTR_ERR(stats);
                        }
                        rcu_assign_pointer(basechain->stats, stats);
                        static_branch_inc(&nft_counters_enabled);
                }

                err = nft_basechain_init(basechain, family, &hook, flags);
                if (err < 0) {
                        nft_chain_release_hook(&hook);
                        kfree(basechain);
                        return err;
                }
        } else {
                if (flags & NFT_CHAIN_BASE)
                        return -EINVAL;
                if (flags & NFT_CHAIN_HW_OFFLOAD)
                        return -EOPNOTSUPP;

                chain = kzalloc(sizeof(*chain), GFP_KERNEL);
                if (chain == NULL)
                        return -ENOMEM;

                chain->flags = flags;
        }
        ctx->chain = chain;

        INIT_LIST_HEAD(&chain->rules);
        chain->handle = nf_tables_alloc_handle(table);
        chain->table = table;

        if (nla[NFTA_CHAIN_NAME]) {
                chain->name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL);
        } else {
                if (!(flags & NFT_CHAIN_BINDING)) {
                        err = -EINVAL;
                        goto err_destroy_chain;
                }

                snprintf(name, sizeof(name), "__chain%llu", ++chain_id);
                chain->name = kstrdup(name, GFP_KERNEL);
        }

        if (!chain->name) {
                err = -ENOMEM;
                goto err_destroy_chain;
        }

        if (nla[NFTA_CHAIN_USERDATA]) {
                chain->udata = nla_memdup(nla[NFTA_CHAIN_USERDATA], GFP_KERNEL);
                if (chain->udata == NULL) {
                        err = -ENOMEM;
                        goto err_destroy_chain;
                }
                chain->udlen = nla_len(nla[NFTA_CHAIN_USERDATA]);
        }

        rules = nf_tables_chain_alloc_rules(chain, 0);
        if (!rules) {
                err = -ENOMEM;
                goto err_destroy_chain;
        }

        *rules = NULL;
        rcu_assign_pointer(chain->rules_gen_0, rules);
        rcu_assign_pointer(chain->rules_gen_1, rules);

        err = nf_tables_register_hook(net, table, chain);
        if (err < 0)
                goto err_destroy_chain;

        trans = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
        if (IS_ERR(trans)) {
                err = PTR_ERR(trans);
                goto err_unregister_hook;
        }

        nft_trans_chain_policy(trans) = NFT_CHAIN_POLICY_UNSET;
        if (nft_is_base_chain(chain))
                nft_trans_chain_policy(trans) = policy;

        err = nft_chain_add(table, chain);
        if (err < 0) {
                nft_trans_destroy(trans);
                goto err_unregister_hook;
        }

        table->use++;

        return 0;
err_unregister_hook:
        nf_tables_unregister_hook(net, table, chain);
err_destroy_chain:
        nf_tables_chain_destroy(ctx);

        return err;
}

static bool nft_hook_list_equal(struct list_head *hook_list1,
                                struct list_head *hook_list2)
{
        struct nft_hook *hook;
        int n = 0, m = 0;

        n = 0;
        list_for_each_entry(hook, hook_list2, list) {
                if (!nft_hook_list_find(hook_list1, hook))
                        return false;

                n++;
        }
        list_for_each_entry(hook, hook_list1, list)
                m++;

        return n == m;
}

static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
                              u32 flags, const struct nlattr *attr,
                              struct netlink_ext_ack *extack)
{
        const struct nlattr * const *nla = ctx->nla;
        struct nft_table *table = ctx->table;
        struct nft_chain *chain = ctx->chain;
        struct nft_base_chain *basechain;
        struct nft_stats *stats = NULL;
        struct nft_chain_hook hook;
        struct nf_hook_ops *ops;
        struct nft_trans *trans;
        int err;

        if (chain->flags ^ flags)
                return -EOPNOTSUPP;

        if (nla[NFTA_CHAIN_HOOK]) {
                if (!nft_is_base_chain(chain)) {
                        NL_SET_BAD_ATTR(extack, attr);
                        return -EEXIST;
                }
                err = nft_chain_parse_hook(ctx->net, nla, &hook, ctx->family,
                                           false);
                if (err < 0)
                        return err;

                basechain = nft_base_chain(chain);
                if (basechain->type != hook.type) {
                        nft_chain_release_hook(&hook);
                        NL_SET_BAD_ATTR(extack, attr);
                        return -EEXIST;
                }

                if (nft_base_chain_netdev(ctx->family, hook.num)) {
                        if (!nft_hook_list_equal(&basechain->hook_list,
                                                 &hook.list)) {
                                nft_chain_release_hook(&hook);
                                NL_SET_BAD_ATTR(extack, attr);
                                return -EEXIST;
                        }
                } else {
                        ops = &basechain->ops;
                        if (ops->hooknum != hook.num ||
                            ops->priority != hook.priority) {
                                nft_chain_release_hook(&hook);
                                NL_SET_BAD_ATTR(extack, attr);
                                return -EEXIST;
                        }
                }
                nft_chain_release_hook(&hook);
        }

        if (nla[NFTA_CHAIN_HANDLE] &&
            nla[NFTA_CHAIN_NAME]) {
                struct nft_chain *chain2;

                chain2 = nft_chain_lookup(ctx->net, table,
                                          nla[NFTA_CHAIN_NAME], genmask);
                if (!IS_ERR(chain2)) {
                        NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_NAME]);
                        return -EEXIST;
                }
        }

        if (nla[NFTA_CHAIN_COUNTERS]) {
                if (!nft_is_base_chain(chain))
                        return -EOPNOTSUPP;

                stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
                if (IS_ERR(stats))
                        return PTR_ERR(stats);
        }

        err = -ENOMEM;
        trans = nft_trans_alloc(ctx, NFT_MSG_NEWCHAIN,
                                sizeof(struct nft_trans_chain));
        if (trans == NULL)
                goto err;

        nft_trans_chain_stats(trans) = stats;
        nft_trans_chain_update(trans) = true;

        if (nla[NFTA_CHAIN_POLICY])
                nft_trans_chain_policy(trans) = policy;
        else
                nft_trans_chain_policy(trans) = -1;

        if (nla[NFTA_CHAIN_HANDLE] &&
            nla[NFTA_CHAIN_NAME]) {
                struct nft_trans *tmp;
                char *name;

                err = -ENOMEM;
                name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL);
                if (!name)
                        goto err;

                err = -EEXIST;
                list_for_each_entry(tmp, &ctx->net->nft.commit_list, list) {
                        if (tmp->msg_type == NFT_MSG_NEWCHAIN &&
                            tmp->ctx.table == table &&
                            nft_trans_chain_update(tmp) &&
                            nft_trans_chain_name(tmp) &&
                            strcmp(name, nft_trans_chain_name(tmp)) == 0) {
                                NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_NAME]);
                                kfree(name);
                                goto err;
                        }
                }

                nft_trans_chain_name(trans) = name;
        }
        list_add_tail(&trans->list, &ctx->net->nft.commit_list);

        return 0;
err:
        free_percpu(stats);
        kfree(trans);
        return err;
}

static struct nft_chain *nft_chain_lookup_byid(const struct net *net,
                                               const struct nlattr *nla)
{
        u32 id = ntohl(nla_get_be32(nla));
        struct nft_trans *trans;

        list_for_each_entry(trans, &net->nft.commit_list, list) {
                struct nft_chain *chain = trans->ctx.chain;

                if (trans->msg_type == NFT_MSG_NEWCHAIN &&
                    id == nft_trans_chain_id(trans))
                        return chain;
        }
        return ERR_PTR(-ENOENT);
}

static int nf_tables_newchain(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_next(net);
        int family = nfmsg->nfgen_family;
        struct nft_chain *chain = NULL;
        const struct nlattr *attr;
        struct nft_table *table;
        u8 policy = NF_ACCEPT;
        struct nft_ctx ctx;
        u64 handle = 0;
        u32 flags = 0;

        lockdep_assert_held(&net->nft.commit_mutex);

        table = nft_table_lookup(net, nla[NFTA_CHAIN_TABLE], family, genmask);
        if (IS_ERR(table)) {
                NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_TABLE]);
                return PTR_ERR(table);
        }

        chain = NULL;
        attr = nla[NFTA_CHAIN_NAME];

        if (nla[NFTA_CHAIN_HANDLE]) {
                handle = be64_to_cpu(nla_get_be64(nla[NFTA_CHAIN_HANDLE]));
                chain = nft_chain_lookup_byhandle(table, handle, genmask);
                if (IS_ERR(chain)) {
                        NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_HANDLE]);
                        return PTR_ERR(chain);
                }
                attr = nla[NFTA_CHAIN_HANDLE];
        } else if (nla[NFTA_CHAIN_NAME]) {
                chain = nft_chain_lookup(net, table, attr, genmask);
                if (IS_ERR(chain)) {
                        if (PTR_ERR(chain) != -ENOENT) {
                                NL_SET_BAD_ATTR(extack, attr);
                                return PTR_ERR(chain);
                        }
                        chain = NULL;
                }
        } else if (!nla[NFTA_CHAIN_ID]) {
                return -EINVAL;
        }

        if (nla[NFTA_CHAIN_POLICY]) {
                if (chain != NULL &&
                    !nft_is_base_chain(chain)) {
                        NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_POLICY]);
                        return -EOPNOTSUPP;
                }

                if (chain == NULL &&
                    nla[NFTA_CHAIN_HOOK] == NULL) {
                        NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_POLICY]);
                        return -EOPNOTSUPP;
                }

                policy = ntohl(nla_get_be32(nla[NFTA_CHAIN_POLICY]));
                switch (policy) {
                case NF_DROP:
                case NF_ACCEPT:
                        break;
                default:
                        return -EINVAL;
                }
        }

        if (nla[NFTA_CHAIN_FLAGS])
                flags = ntohl(nla_get_be32(nla[NFTA_CHAIN_FLAGS]));
        else if (chain)
                flags = chain->flags;

        if (flags & ~NFT_CHAIN_FLAGS)
                return -EOPNOTSUPP;

        nft_ctx_init(&ctx, net, skb, nlh, family, table, chain, nla);

        if (chain != NULL) {
                if (nlh->nlmsg_flags & NLM_F_EXCL) {
                        NL_SET_BAD_ATTR(extack, attr);
                        return -EEXIST;
                }
                if (nlh->nlmsg_flags & NLM_F_REPLACE)
                        return -EOPNOTSUPP;

                flags |= chain->flags & NFT_CHAIN_BASE;
                return nf_tables_updchain(&ctx, genmask, policy, flags, attr,
                                          extack);
        }

        return nf_tables_addchain(&ctx, family, genmask, policy, flags);
}

static int nf_tables_delchain(struct net *net, struct sock *nlsk,
                              struct sk_buff *skb, const struct nlmsghdr *nlh,
                              const struct nlattr * const nla[],
                              struct netlink_ext_ack *extack)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u8 genmask = nft_genmask_next(net);
        int family = nfmsg->nfgen_family;
        const struct nlattr *attr;
        struct nft_table *table;
        struct nft_chain *chain;
        struct nft_rule *rule;
        struct nft_ctx ctx;
        u64 handle;
        u32 use;
        int err;

        table = nft_table_lookup(net, nla[NFTA_CHAIN_TABLE], family, genmask);
        if (IS_ERR(table)) {
                NL_SET_BAD_ATTR(extack, nla[NFTA_CHAIN_TABLE]);
                return PTR_ERR(table);
        }

        if (nla[NFTA_CHAIN_HANDLE]) {
                attr = nla[NFTA_CHAIN_HANDLE];
                handle = be64_to_cpu(nla_get_be64(attr));
                chain = nft_chain_lookup_byhandle(table, handle, genmask);
        } else {
                attr = nla[NFTA_CHAIN_NAME];
                chain = nft_chain_lookup(net, table, attr, genmask);
        }
        if (IS_ERR(chain)) {
                NL_SET_BAD_ATTR(extack, attr);
                return PTR_ERR(chain);
        }

        if (nlh->nlmsg_flags & NLM_F_NONREC &&
            chain->use > 0)
                return -EBUSY;

        nft_ctx_init(&ctx, net, skb, nlh, family, table, chain, nla);

        use = chain->use;
        list_for_each_entry(rule, &chain->rules, list) {
                if (!nft_is_active_next(net, rule))
                        continue;
                use--;

                err = nft_delrule(&ctx, rule);
                if (err < 0)
                        return err;
        }

        /* There are rules and elements that are still holding references to us,
         * we cannot do a recursive removal in this case.
         */
        if (use > 0) {
                NL_SET_BAD_ATTR(extack, attr);
                return -EBUSY;
        }

        return nft_delchain(&ctx);
}

/*
 * Expressions
 */

/**
 *      nft_register_expr - register nf_tables expr type
 *      @type: expr type
 *
 *      Registers the expr type for use with nf_tables. Returns zero on
 *      success or a negative errno code otherwise.
 */
int nft_register_expr(struct nft_expr_type *type)
{
        nfnl_lock(NFNL_SUBSYS_NFTABLES);
        if (type->family == NFPROTO_UNSPEC)
                list_add_tail_rcu(&type->list, &nf_tables_expressions);
        else
                list_add_rcu(&type->list, &nf_tables_expressions);
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
        return 0;
}
EXPORT_SYMBOL_GPL(nft_register_expr);

/**
 *      nft_unregister_expr - unregister nf_tables expr type
 *      @type: expr type
 *
 *      Unregisters the expr typefor use with nf_tables.
 */
void nft_unregister_expr(struct nft_expr_type *type)
{
        nfnl_lock(NFNL_SUBSYS_NFTABLES);
        list_del_rcu(&type->list);
        nfnl_unlock(NFNL_SUBSYS_NFTABLES);
}
EXPORT_SYMBOL_GPL(nft_unregister_expr);

static const struct nft_expr_type *__nft_expr_type_get(u8 family,
                                                       struct nlattr *nla)
{
        const struct nft_expr_type *type, *candidate = NULL;

        list_for_each_entry(type, &nf_tables_expressions, list) {
                if (!nla_strcmp(nla, type->name)) {
                        if (!type->family && !candidate)
                                candidate = type;
                        else if (type->family == family)
                                candidate = type;
                }
        }
        return candidate;
}

#ifdef CONFIG_MODULES
static int nft_expr_type_request_module(struct net *net, u8 family,
                                        struct nlattr *nla)
{
        if (nft_request_module(net, "nft-expr-%u-%.*s", family,
                               nla_len(nla), (char *)nla_data(nla)) == -EAGAIN)
                return -EAGAIN;

        return 0;
}
#endif

static const struct nft_expr_type *nft_expr_type_get(struct net *net,
                                                     u8 family,
                                                     struct nlattr *nla)
{
        const struct nft_expr_type *type;

        if (nla == NULL)
                return ERR_PTR(-EINVAL);

        type = __nft_expr_type_get(family, nla);
        if (type != NULL && try_module_get(type->owner))
                return type;

        lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
        if (type == NULL) {
                if (nft_expr_type_request_module(net, family, nla) == -EAGAIN)
                        return ERR_PTR(-EAGAIN);

                if (nft_request_module(net, "nft-expr-%.*s",
                                       nla_len(nla),
                                       (char *)nla_data(nla)) == -EAGAIN)
                        return ERR_PTR(-EAGAIN);
        }
#endif
        return ERR_PTR(-ENOENT);
}

static const struct nla_policy nft_expr_policy[NFTA_EXPR_MAX + 1] = {
        [NFTA_EXPR_NAME]        = { .type = NLA_STRING,
                                    .len = NFT_MODULE_AUTOLOAD_LIMIT },
        [NFTA_EXPR_DATA]        = { .type = NLA_NESTED },
};

static int nf_tables_fill_expr_info(struct sk_buff *skb,
                                    const struct nft_expr *expr)
{
        if (nla_put_string(skb, NFTA_EXPR_NAME, expr->ops->type->name))
                goto nla_put_failure;

        if (expr->ops->dump) {
                struct nlattr *data = nla_nest_start_noflag(skb,
                                                            NFTA_EXPR_DATA);
                if (data == NULL)
                        goto nla_put_failure;
                if (expr->ops->dump(skb, expr) < 0)
                        goto nla_put_failure;
                nla_nest_end(skb, data);
        }

        return skb->len;

nla_put_failure:
        return -1;
};

int nft_expr_dump(struct sk_buff *skb, unsigned int attr,
                  const struct nft_expr *expr)
{
        struct nlattr *nest;

        nest = nla_nest_start_noflag(skb, attr);
        if (!nest)
                goto nla_put_failure;
        if (nf_tables_fill_expr_info(skb, expr) < 0)
                goto nla_put_failure;
        nla_nest_end(skb, nest);
        return 0;

nla_put_failure:
        return -1;
}

struct nft_expr_info {
        const struct nft_expr_ops       *ops;
        const struct nlattr             *attr;
        struct nlattr                   *tb[NFT_EXPR_MAXATTR + 1];
};

static int nf_tables_expr_parse(const struct nft_ctx *ctx,
                                const struct nlattr *nla,
                                struct nft_expr_info *info)
{
        const struct nft_expr_type *type;
        const struct nft_expr_ops *ops;
        struct nlattr *tb[NFTA_EXPR_MAX + 1];
        int err;

        err = nla_parse_nested_deprecated(tb, NFTA_EXPR_MAX, nla,
                                          nft_expr_policy, NULL);
        if (err < 0)
                return err;

        type = nft_expr_type_get(ctx->net, ctx->family, tb[NFTA_EXPR_NAME]);
        if (IS_ERR(type))
                return PTR_ERR(type);

        if (tb[NFTA_EXPR_DATA]) {
                err = nla_parse_nested_deprecated(info->tb, type->maxattr,
                                                  tb[NFTA_EXPR_DATA],
                                                  type->policy, NULL);
                if (err < 0)
                        goto err1;
        } else
                memset(info->tb, 0, sizeof(info->tb[0]) * (type->maxattr + 1));

        if (type->select_ops != NULL) {
                ops = type->select_ops(ctx,
                                       (const struct nlattr * const *)info->tb);
                if (IS_ERR(ops)) {
                        err = PTR_ERR(ops);
#ifdef CONFIG_MODULES
                        if (err == -EAGAIN)
                                if (nft_expr_type_request_module(ctx->net,
                                                                 ctx->family,
                                                                 tb[NFTA_EXPR_NAME]) != -EAGAIN)
                                        err = -ENOENT;
#endif
                        goto err1;
                }
        } else
                ops = type->ops;

        info->attr = nla;
        info->ops = ops;

        return 0;

err1:
        module_put(type->owner);
        return err;
}

static int nf_tables_newexpr(const struct nft_ctx *ctx,
                             const struct nft_expr_info *info,
                             struct nft_expr *expr)
{
        const struct nft_expr_ops *ops = info->ops;
        int err;

        expr->ops = ops;
        if (ops->init) {
                err = ops->init(ctx, expr, (const struct nlattr **)info->tb);
                if (err < 0)
                        goto err1;
        }

        return 0;
err1:
        expr->ops = NULL;
        return err;
}

static void nf_tables_expr_destroy(const struct nft_ctx *ctx,
                                   struct nft_expr *expr)
{
        const struct nft_expr_type *type = expr->ops->type;

        if (expr->ops->destroy)
                expr->ops->destroy(ctx, expr);
        module_put(type->owner);
}

static struct nft_expr *nft_expr_init(const struct nft_ctx *ctx,
                                      const struct nlattr *nla)
{
        struct nft_expr_info info;
        struct nft_expr *expr;
        struct module *owner;
        int err;

        err = nf_tables_expr_parse(ctx, nla, &info);
        if (err < 0)
                goto err1;

        err = -ENOMEM;
        expr = kzalloc(info.ops->size, GFP_KERNEL);
        if (expr == NULL)
                goto err2;

        err = nf_tables_newexpr(ctx, &info, expr);
        if (err < 0)
                goto err3;

        return expr;
err3:
        kfree(expr);
err2:
        owner = info.ops->type->owner;
        if (info.ops->type->release_ops)
                info.ops->type->release_ops(info.ops);

        module_put(owner);
err1:
        return ERR_PTR(err);
}

int nft_expr_clone(struct nft_expr *dst, struct nft_expr *src)
{
        int err;

        if (src->ops->clone) {
                dst->ops = src->ops;
                err = src->ops->clone(dst, src);
                if (err < 0)
                        return err;
        } else {
                memcpy(dst, src, src->ops->size);
        }

        __module_get(src->ops->type->owner);

        return 0;
}

void nft_expr_destroy(const struct nft_ctx *ctx, struct nft_expr *expr)
{
        nf_tables_expr_destroy(ctx, expr);
        kfree(expr);
}

/*
 * Rules
 */

static struct nft_rule *__nft_rule_lookup(const struct nft_chain *chain,
                                          u64 handle)
{
        struct nft_rule *rule;

        // FIXME: this sucks
        list_for_each_entry_rcu(rule, &chain->rules, list) {
                if (handle == rule->handle)
                        return rule;
        }

        return ERR_PTR(-ENOENT);
}

static struct nft_rule *nft_rule_lookup(const struct nft_chain *chain,
                                        const struct nlattr *nla)
{
        if (nla == NULL)
                return ERR_PTR(-EINVAL);

        return __nft_rule_lookup(chain, be64_to_cpu(nla_get_be64(nla)));
}

static const struct nla_policy nft_rule_policy[NFTA_RULE_MAX + 1] = {
        [NFTA_RULE_TABLE]       = { .type = NLA_STRING,
                                    .len = NFT_TABLE_MAXNAMELEN - 1 },
        [NFTA_RULE_CHAIN]       = { .type = NLA_STRING,
                                    .len = NFT_CHAIN_MAXNAMELEN - 1 },
        [NFTA_RULE_HANDLE]      = { .type = NLA_U64 },
        [NFTA_RULE_EXPRESSIONS] = { .type = NLA_NESTED },
        [NFTA_RULE_COMPAT]      = { .type = NLA_NESTED },
        [NFTA_RULE_POSITION]    = { .type = NLA_U64 },
        [NFTA_RULE_USERDATA]    = { .type = NLA_BINARY,
                                    .len = NFT_USERDATA_MAXLEN },
        [NFTA_RULE_ID]          = { .type = NLA_U32 },
        [NFTA_RULE_POSITION_ID] = { .type = NLA_U32 },
        [NFTA_RULE_CHAIN_ID]    = { .type = NLA_U32 },
};

static int nf_tables_fill_rule_info(struct sk_buff *skb, struct net *net,
                                    u32 portid, u32 seq, int event,
                                    u32 flags, int family,
                                    const struct nft_table *table,
                                    const struct nft_chain *chain,
                                    const struct nft_rule *rule,
                                    const struct nft_rule *prule)
{
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;
        const struct nft_expr *expr, *next;
        struct nlattr *list;
        u16 type = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, event);

        nlh = nlmsg_put(skb, portid, seq, type, sizeof(struct nfgenmsg), flags);
        if (nlh == NULL)
                goto nla_put_failure;

        nfmsg = nlmsg_data(nlh);
        nfmsg->nfgen_family     = family;
        nfmsg->version          = NFNETLINK_V0;
        nfmsg->res_id           = htons(net->nft.base_seq & 0xffff);

        if (nla_put_string(skb, NFTA_RULE_TABLE, table->name))
                goto nla_put_failure;
        if (nla_put_string(skb, NFTA_RULE_CHAIN, chain->name))
                goto nla_put_failure;
        if (nla_put_be64(skb, NFTA_RULE_HANDLE, cpu_to_be64(rule->handle),
                         NFTA_RULE_PAD))
                goto nla_put_failure;

        if (event != NFT_MSG_DELRULE && prule) {
                if (nla_put_be64(skb, NFTA_RULE_POSITION,
                                 cpu_to_be64(prule->handle),
                                 NFTA_RULE_PAD))
                        goto nla_put_failure;
        }

        list = nla_nest_start_noflag(skb, NFTA_RULE_EXPRESSIONS);
        if (list == NULL)
                goto nla_put_failure;
        nft_rule_for_each_expr(expr, next, rule) {
                if (nft_expr_dump(skb, NFTA_LIST_ELEM, expr) < 0)
                        goto nla_put_failure;
        }
        nla_nest_end(skb, list);

        if (rule->udata) {
                struct nft_userdata *udata = nft_userdata(rule);
                if (nla_put(skb, NFTA_RULE_USERDATA, udata->len + 1,
                            udata->data) < 0)
                        goto nla_put_failure;
        }

        nlmsg_end(skb, nlh);
        return 0;

nla_put_failure:
        nlmsg_trim(skb, nlh);
        return -1;
}

static void nf_tables_rule_notify(const struct nft_ctx *ctx,
                                  const struct nft_rule *rule, int event)
{
        struct sk_buff *skb;
        int err;
        char *buf = kasprintf(GFP_KERNEL, "%s:%llu;%s:%llu",
                              ctx->table->name, ctx->table->handle,
                              ctx->chain->name, ctx->chain->handle);

        audit_log_nfcfg(buf,
                        ctx->family,
                        rule->handle,
                        event == NFT_MSG_NEWRULE ?
                                AUDIT_NFT_OP_RULE_REGISTER :
                                AUDIT_NFT_OP_RULE_UNREGISTER,
                        GFP_KERNEL);
        kfree(buf);

        if (!ctx->report &&
            !nfnetlink_has_listeners(ctx->net, NFNLGRP_NFTABLES))
                return;

        skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
        if (skb == NULL)
                goto err;

        err = nf_tables_fill_rule_info(skb, ctx->net, ctx->portid, ctx->seq,
                                       event, 0, ctx->family, ctx->table,
                                       ctx->chain, rule, NULL);
        if (err < 0) {
                kfree_skb(skb);
                goto err;
        }

        nft_notify_enqueue(skb, ctx->report, &ctx->net->nft.notify_list);
        return;
err:
        nfnetlink_set_err(ctx->net, ctx->portid, NFNLGRP_NFTABLES, -ENOBUFS);
}

struct nft_rule_dump_ctx {
        char *table;
        char *chain;
};

static int __nf_tables_dump_rules(struct sk_buff *skb,
                                  unsigned int *idx,
                                  struct netlink_callback *cb,
                                  const struct nft_table *table,
                                  const struct nft_chain *chain)
{
        struct net *net = sock_net(skb->sk);
        const struct nft_rule *rule, *prule;
        unsigned int s_idx = cb->args[0];

        prule = NULL;
        list_for_each_entry_rcu(rule, &chain->rules, list) {
                if (!nft_is_active(net, rule))
                        goto cont_skip;
                if (*idx < s_idx)
                        goto cont;
                if (*idx > s_idx) {
                        memset(&cb->args[1], 0,
                                        sizeof(cb->args) - sizeof(cb->args[0]));
                }
                if (nf_tables_fill_rule_info(skb, net, NETLINK_CB(cb->skb).portid,
                                        cb->nlh->nlmsg_seq,
                                        NFT_MSG_NEWRULE,
                                        NLM_F_MULTI | NLM_F_APPEND,
                                        table->family,
                                        table, chain, rule, prule) < 0)
                        return 1;

                nl_dump_check_consistent(cb, nlmsg_hdr(skb));
cont:
                prule = rule;
cont_skip:
                (*idx)++;
        }
        return 0;
}

static int nf_tables_dump_rules(struct sk_buff *skb,
                                struct netlink_callback *cb)
{
        const struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
        const struct nft_rule_dump_ctx *ctx = cb->data;
        struct nft_table *table;
        const struct nft_chain *chain;
        unsigned int idx = 0;
        struct net *net = sock_net(skb->sk);
        int family = nfmsg->nfgen_family;

        rcu_read_lock();
        cb->seq = net->nft.base_seq;

        list_for_each_entry_rcu(table, &net->nft.tables, list) {
                if (family != NFPROTO_UNSPEC && family != table->family)
                        continue;

                if (ctx && ctx->table && strcmp(ctx->table, table->name) != 0)
                        continue;

                if (ctx && ctx->table && ctx->chain) {
                        struct rhlist_head *list, *tmp;

                        list = rhltable_lookup(&table->chains_ht, ctx->chain,
                                               nft_chain_ht_params);
                        if (!list)
                                goto done;

                        rhl_for_each_entry_rcu(chain, tmp, list, rhlhead) {
                                if (!nft_is_active(net, chain))
                                        continue;
                                __nf_tables_dump_rules(skb, &idx,
                                                       cb, table, chain);
                                break;
                        }
                        goto done;
                }

                list_for_each_entry_rcu(chain, &table->chains, list) {
                        if (__nf_tables_dump_rules(skb, &idx, cb, table, chain))
                                goto done;
                }

                if (ctx && ctx->table)
                        break;
        }
done:
        rcu_read_unlock();

        cb->args[0] = idx;
        return skb->len;
}

static int nf_tables_dump_rules_start(struct netlink_callback *cb)
{
        const struct nlattr * const *nla = cb->data;
        struct nft_rule_dump_ctx *ctx = NULL;

        if (nla[NFTA_RULE_TABLE] || nla[NFTA_RULE_CHAIN]) {
                ctx = kzalloc(sizeof(*ctx), GFP_ATOMIC);
                if (!ctx)
                        return -ENOMEM;

                if (nla[NFTA_RULE_TABLE]) {
                        ctx->table = nla_strdup(nla[NFTA_RULE_TABLE],
                                                        GFP_ATOMIC);
                        if (!ctx->table) {
                                kfree(ctx);
                                return -ENOMEM;
                        }
                }
                if (nla[NFTA_RULE_CHAIN]) {
                        ctx->chain = nla_strdup(nla[NFTA_RULE_CHAIN],
                                                GFP_ATOMIC);
                        if (!ctx->chain) {
                                kfree(ctx->table);
                                kfree(ctx);
                                return -ENOMEM;
                        }
                }
        }

        cb->data = ctx;