// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2000-2002 Joakim Axelsson <gozem@linux.nu>
 *                         Patrick Schaaf <bof@bof.de>
 * Copyright (C) 2003-2013 Jozsef Kadlecsik <kadlec@netfilter.org>
 */

/* Kernel module for IP set management */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ip.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/rculist.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/ipset/ip_set.h>

static LIST_HEAD(ip_set_type_list);             /* all registered set types */
static DEFINE_MUTEX(ip_set_type_mutex);         /* protects ip_set_type_list */
static DEFINE_RWLOCK(ip_set_ref_lock);          /* protects the set refs */

struct ip_set_net {
        struct ip_set * __rcu *ip_set_list;     /* all individual sets */
        ip_set_id_t     ip_set_max;     /* max number of sets */
        bool            is_deleted;     /* deleted by ip_set_net_exit */
        bool            is_destroyed;   /* all sets are destroyed */
};

static unsigned int ip_set_net_id __read_mostly;

static struct ip_set_net *ip_set_pernet(struct net *net)
{
        return net_generic(net, ip_set_net_id);
}

#define IP_SET_INC      64
#define STRNCMP(a, b)   (strncmp(a, b, IPSET_MAXNAMELEN) == 0)

static unsigned int max_sets;

module_param(max_sets, int, 0600);
MODULE_PARM_DESC(max_sets, "maximal number of sets");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jozsef Kadlecsik <kadlec@netfilter.org>");
MODULE_DESCRIPTION("core IP set support");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_IPSET);

/* When the nfnl mutex or ip_set_ref_lock is held: */
#define ip_set_dereference(p)           \
        rcu_dereference_protected(p,    \
                lockdep_nfnl_is_held(NFNL_SUBSYS_IPSET) || \
                lockdep_is_held(&ip_set_ref_lock))
#define ip_set(inst, id)                \
        ip_set_dereference((inst)->ip_set_list)[id]
#define ip_set_ref_netlink(inst,id)     \
        rcu_dereference_raw((inst)->ip_set_list)[id]

/* The set types are implemented in modules and registered set types
 * can be found in ip_set_type_list. Adding/deleting types is
 * serialized by ip_set_type_mutex.
 */

static void
ip_set_type_lock(void)
{
        mutex_lock(&ip_set_type_mutex);
}

static void
ip_set_type_unlock(void)
{
        mutex_unlock(&ip_set_type_mutex);
}

/* Register and deregister settype */

static struct ip_set_type *
find_set_type(const char *name, u8 family, u8 revision)
{
        struct ip_set_type *type;

        list_for_each_entry_rcu(type, &ip_set_type_list, list,
                                lockdep_is_held(&ip_set_type_mutex))
                if (STRNCMP(type->name, name) &&
                    (type->family == family ||
                     type->family == NFPROTO_UNSPEC) &&
                    revision >= type->revision_min &&
                    revision <= type->revision_max)
                        return type;
        return NULL;
}

/* Unlock, try to load a set type module and lock again */
static bool
load_settype(const char *name)
{
        nfnl_unlock(NFNL_SUBSYS_IPSET);
        pr_debug("try to load ip_set_%s\n", name);
        if (request_module("ip_set_%s", name) < 0) {
                pr_warn("Can't find ip_set type %s\n", name);
                nfnl_lock(NFNL_SUBSYS_IPSET);
                return false;
        }
        nfnl_lock(NFNL_SUBSYS_IPSET);
        return true;
}

/* Find a set type and reference it */
#define find_set_type_get(name, family, revision, found)        \
        __find_set_type_get(name, family, revision, found, false)

static int
__find_set_type_get(const char *name, u8 family, u8 revision,
                    struct ip_set_type **found, bool retry)
{
        struct ip_set_type *type;
        int err;

        if (retry && !load_settype(name))
                return -IPSET_ERR_FIND_TYPE;

        rcu_read_lock();
        *found = find_set_type(name, family, revision);
        if (*found) {
                err = !try_module_get((*found)->me) ? -EFAULT : 0;
                goto unlock;
        }
        /* Make sure the type is already loaded
         * but we don't support the revision
         */
        list_for_each_entry_rcu(type, &ip_set_type_list, list)
                if (STRNCMP(type->name, name)) {
                        err = -IPSET_ERR_FIND_TYPE;
                        goto unlock;
                }
        rcu_read_unlock();

        return retry ? -IPSET_ERR_FIND_TYPE :
                __find_set_type_get(name, family, revision, found, true);

unlock:
        rcu_read_unlock();
        return err;
}

/* Find a given set type by name and family.
 * If we succeeded, the supported minimal and maximum revisions are
 * filled out.
 */
#define find_set_type_minmax(name, family, min, max) \
        __find_set_type_minmax(name, family, min, max, false)

static int
__find_set_type_minmax(const char *name, u8 family, u8 *min, u8 *max,
                       bool retry)
{
        struct ip_set_type *type;
        bool found = false;

        if (retry && !load_settype(name))
                return -IPSET_ERR_FIND_TYPE;

        *min = 255; *max = 0;
        rcu_read_lock();
        list_for_each_entry_rcu(type, &ip_set_type_list, list)
                if (STRNCMP(type->name, name) &&
                    (type->family == family ||
                     type->family == NFPROTO_UNSPEC)) {
                        found = true;
                        if (type->revision_min < *min)
                                *min = type->revision_min;
                        if (type->revision_max > *max)
                                *max = type->revision_max;
                }
        rcu_read_unlock();
        if (found)
                return 0;

        return retry ? -IPSET_ERR_FIND_TYPE :
                __find_set_type_minmax(name, family, min, max, true);
}

#define family_name(f)  ((f) == NFPROTO_IPV4 ? "inet" : \
                         (f) == NFPROTO_IPV6 ? "inet6" : "any")

/* Register a set type structure. The type is identified by
 * the unique triple of name, family and revision.
 */
int
ip_set_type_register(struct ip_set_type *type)
{
        int ret = 0;

        if (type->protocol != IPSET_PROTOCOL) {
                pr_warn("ip_set type %s, family %s, revision %u:%u uses wrong protocol version %u (want %u)\n",
                        type->name, family_name(type->family),
                        type->revision_min, type->revision_max,
                        type->protocol, IPSET_PROTOCOL);
                return -EINVAL;
        }

        ip_set_type_lock();
        if (find_set_type(type->name, type->family, type->revision_min)) {
                /* Duplicate! */
                pr_warn("ip_set type %s, family %s with revision min %u already registered!\n",
                        type->name, family_name(type->family),
                        type->revision_min);
                ip_set_type_unlock();
                return -EINVAL;
        }
        list_add_rcu(&type->list, &ip_set_type_list);
        pr_debug("type %s, family %s, revision %u:%u registered.\n",
                 type->name, family_name(type->family),
                 type->revision_min, type->revision_max);
        ip_set_type_unlock();

        return ret;
}
EXPORT_SYMBOL_GPL(ip_set_type_register);

/* Unregister a set type. There's a small race with ip_set_create */
void
ip_set_type_unregister(struct ip_set_type *type)
{
        ip_set_type_lock();
        if (!find_set_type(type->name, type->family, type->revision_min)) {
                pr_warn("ip_set type %s, family %s with revision min %u not registered\n",
                        type->name, family_name(type->family),
                        type->revision_min);
                ip_set_type_unlock();
                return;
        }
        list_del_rcu(&type->list);
        pr_debug("type %s, family %s with revision min %u unregistered.\n",
                 type->name, family_name(type->family), type->revision_min);
        ip_set_type_unlock();

        synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ip_set_type_unregister);

/* Utility functions */
void *
ip_set_alloc(size_t size)
{
        return kvzalloc(size, GFP_KERNEL_ACCOUNT);
}
EXPORT_SYMBOL_GPL(ip_set_alloc);

void
ip_set_free(void *members)
{
        pr_debug("%p: free with %s\n", members,
                 is_vmalloc_addr(members) ? "vfree" : "kfree");
        kvfree(members);
}
EXPORT_SYMBOL_GPL(ip_set_free);

static bool
flag_nested(const struct nlattr *nla)
{
        return nla->nla_type & NLA_F_NESTED;
}

static const struct nla_policy ipaddr_policy[IPSET_ATTR_IPADDR_MAX + 1] = {
        [IPSET_ATTR_IPADDR_IPV4]        = { .type = NLA_U32 },
        [IPSET_ATTR_IPADDR_IPV6]        = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
};

int
ip_set_get_ipaddr4(struct nlattr *nla,  __be32 *ipaddr)
{
        struct nlattr *tb[IPSET_ATTR_IPADDR_MAX + 1];

        if (unlikely(!flag_nested(nla)))
                return -IPSET_ERR_PROTOCOL;
        if (nla_parse_nested(tb, IPSET_ATTR_IPADDR_MAX, nla,
                             ipaddr_policy, NULL))
                return -IPSET_ERR_PROTOCOL;
        if (unlikely(!ip_set_attr_netorder(tb, IPSET_ATTR_IPADDR_IPV4)))
                return -IPSET_ERR_PROTOCOL;

        *ipaddr = nla_get_be32(tb[IPSET_ATTR_IPADDR_IPV4]);
        return 0;
}
EXPORT_SYMBOL_GPL(ip_set_get_ipaddr4);

int
ip_set_get_ipaddr6(struct nlattr *nla, union nf_inet_addr *ipaddr)
{
        struct nlattr *tb[IPSET_ATTR_IPADDR_MAX + 1];

        if (unlikely(!flag_nested(nla)))
                return -IPSET_ERR_PROTOCOL;

        if (nla_parse_nested(tb, IPSET_ATTR_IPADDR_MAX, nla,
                             ipaddr_policy, NULL))
                return -IPSET_ERR_PROTOCOL;
        if (unlikely(!ip_set_attr_netorder(tb, IPSET_ATTR_IPADDR_IPV6)))
                return -IPSET_ERR_PROTOCOL;

        memcpy(ipaddr, nla_data(tb[IPSET_ATTR_IPADDR_IPV6]),
               sizeof(struct in6_addr));
        return 0;
}
EXPORT_SYMBOL_GPL(ip_set_get_ipaddr6);

static u32
ip_set_timeout_get(const unsigned long *timeout)
{
        u32 t;

        if (*timeout == IPSET_ELEM_PERMANENT)
                return 0;

        t = jiffies_to_msecs(*timeout - jiffies) / MSEC_PER_SEC;
        /* Zero value in userspace means no timeout */
        return t == 0 ? 1 : t;
}

static char *
ip_set_comment_uget(struct nlattr *tb)
{
        return nla_data(tb);
}

/* Called from uadd only, protected by the set spinlock.
 * The kadt functions don't use the comment extensions in any way.
 */
void
ip_set_init_comment(struct ip_set *set, struct ip_set_comment *comment,
                    const struct ip_set_ext *ext)
{
        struct ip_set_comment_rcu *c = rcu_dereference_protected(comment->c, 1);
        size_t len = ext->comment ? strlen(ext->comment) : 0;

        if (unlikely(c)) {
                set->ext_size -= sizeof(*c) + strlen(c->str) + 1;
                kfree_rcu(c, rcu);
                rcu_assign_pointer(comment->c, NULL);
        }
        if (!len)
                return;
        if (unlikely(len > IPSET_MAX_COMMENT_SIZE))
                len = IPSET_MAX_COMMENT_SIZE;
        c = kmalloc(sizeof(*c) + len + 1, GFP_ATOMIC);
        if (unlikely(!c))
                return;
        strlcpy(c->str, ext->comment, len + 1);
        set->ext_size += sizeof(*c) + strlen(c->str) + 1;
        rcu_assign_pointer(comment->c, c);
}
EXPORT_SYMBOL_GPL(ip_set_init_comment);

/* Used only when dumping a set, protected by rcu_read_lock() */
static int
ip_set_put_comment(struct sk_buff *skb, const struct ip_set_comment *comment)
{
        struct ip_set_comment_rcu *c = rcu_dereference(comment->c);

        if (!c)
                return 0;
        return nla_put_string(skb, IPSET_ATTR_COMMENT, c->str);
}

/* Called from uadd/udel, flush or the garbage collectors protected
 * by the set spinlock.
 * Called when the set is destroyed and when there can't be any user
 * of the set data anymore.
 */
static void
ip_set_comment_free(struct ip_set *set, void *ptr)
{
        struct ip_set_comment *comment = ptr;
        struct ip_set_comment_rcu *c;

        c = rcu_dereference_protected(comment->c, 1);
        if (unlikely(!c))
                return;
        set->ext_size -= sizeof(*c) + strlen(c->str) + 1;
        kfree_rcu(c, rcu);
        rcu_assign_pointer(comment->c, NULL);
}

typedef void (*destroyer)(struct ip_set *, void *);
/* ipset data extension types, in size order */

const struct ip_set_ext_type ip_set_extensions[] = {
        [IPSET_EXT_ID_COUNTER] = {
                .type   = IPSET_EXT_COUNTER,
                .flag   = IPSET_FLAG_WITH_COUNTERS,
                .len    = sizeof(struct ip_set_counter),
                .align  = __alignof__(struct ip_set_counter),
        },
        [IPSET_EXT_ID_TIMEOUT] = {
                .type   = IPSET_EXT_TIMEOUT,
                .len    = sizeof(unsigned long),
                .align  = __alignof__(unsigned long),
        },
        [IPSET_EXT_ID_SKBINFO] = {
                .type   = IPSET_EXT_SKBINFO,
                .flag   = IPSET_FLAG_WITH_SKBINFO,
                .len    = sizeof(struct ip_set_skbinfo),
                .align  = __alignof__(struct ip_set_skbinfo),
        },
        [IPSET_EXT_ID_COMMENT] = {
                .type    = IPSET_EXT_COMMENT | IPSET_EXT_DESTROY,
                .flag    = IPSET_FLAG_WITH_COMMENT,
                .len     = sizeof(struct ip_set_comment),
                .align   = __alignof__(struct ip_set_comment),
                .destroy = ip_set_comment_free,
        },
};
EXPORT_SYMBOL_GPL(ip_set_extensions);

static bool
add_extension(enum ip_set_ext_id id, u32 flags, struct nlattr *tb[])
{
        return ip_set_extensions[id].flag ?
                (flags & ip_set_extensions[id].flag) :
                !!tb[IPSET_ATTR_TIMEOUT];
}

size_t
ip_set_elem_len(struct ip_set *set, struct nlattr *tb[], size_t len,
                size_t align)
{
        enum ip_set_ext_id id;
        u32 cadt_flags = 0;

        if (tb[IPSET_ATTR_CADT_FLAGS])
                cadt_flags = ip_set_get_h32(tb[IPSET_ATTR_CADT_FLAGS]);
        if (cadt_flags & IPSET_FLAG_WITH_FORCEADD)
                set->flags |= IPSET_CREATE_FLAG_FORCEADD;
        if (!align)
                align = 1;
        for (id = 0; id < IPSET_EXT_ID_MAX; id++) {
                if (!add_extension(id, cadt_flags, tb))
                        continue;
                if (align < ip_set_extensions[id].align)
                        align = ip_set_extensions[id].align;
                len = ALIGN(len, ip_set_extensions[id].align);
                set->offset[id] = len;
                set->extensions |= ip_set_extensions[id].type;
                len += ip_set_extensions[id].len;
        }
        return ALIGN(len, align);
}
EXPORT_SYMBOL_GPL(ip_set_elem_len);

int
ip_set_get_extensions(struct ip_set *set, struct nlattr *tb[],
                      struct ip_set_ext *ext)
{
        u64 fullmark;

        if (unlikely(!ip_set_optattr_netorder(tb, IPSET_ATTR_TIMEOUT) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_PACKETS) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_BYTES) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_SKBMARK) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_SKBPRIO) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_SKBQUEUE)))
                return -IPSET_ERR_PROTOCOL;

        if (tb[IPSET_ATTR_TIMEOUT]) {
                if (!SET_WITH_TIMEOUT(set))
                        return -IPSET_ERR_TIMEOUT;
                ext->timeout = ip_set_timeout_uget(tb[IPSET_ATTR_TIMEOUT]);
        }
        if (tb[IPSET_ATTR_BYTES] || tb[IPSET_ATTR_PACKETS]) {
                if (!SET_WITH_COUNTER(set))
                        return -IPSET_ERR_COUNTER;
                if (tb[IPSET_ATTR_BYTES])
                        ext->bytes = be64_to_cpu(nla_get_be64(
                                                 tb[IPSET_ATTR_BYTES]));
                if (tb[IPSET_ATTR_PACKETS])
                        ext->packets = be64_to_cpu(nla_get_be64(
                                                   tb[IPSET_ATTR_PACKETS]));
        }
        if (tb[IPSET_ATTR_COMMENT]) {
                if (!SET_WITH_COMMENT(set))
                        return -IPSET_ERR_COMMENT;
                ext->comment = ip_set_comment_uget(tb[IPSET_ATTR_COMMENT]);
        }
        if (tb[IPSET_ATTR_SKBMARK]) {
                if (!SET_WITH_SKBINFO(set))
                        return -IPSET_ERR_SKBINFO;
                fullmark = be64_to_cpu(nla_get_be64(tb[IPSET_ATTR_SKBMARK]));
                ext->skbinfo.skbmark = fullmark >> 32;
                ext->skbinfo.skbmarkmask = fullmark & 0xffffffff;
        }
        if (tb[IPSET_ATTR_SKBPRIO]) {
                if (!SET_WITH_SKBINFO(set))
                        return -IPSET_ERR_SKBINFO;
                ext->skbinfo.skbprio =
                        be32_to_cpu(nla_get_be32(tb[IPSET_ATTR_SKBPRIO]));
        }
        if (tb[IPSET_ATTR_SKBQUEUE]) {
                if (!SET_WITH_SKBINFO(set))
                        return -IPSET_ERR_SKBINFO;
                ext->skbinfo.skbqueue =
                        be16_to_cpu(nla_get_be16(tb[IPSET_ATTR_SKBQUEUE]));
        }
        return 0;
}
EXPORT_SYMBOL_GPL(ip_set_get_extensions);

static u64
ip_set_get_bytes(const struct ip_set_counter *counter)
{
        return (u64)atomic64_read(&(counter)->bytes);
}

static u64
ip_set_get_packets(const struct ip_set_counter *counter)
{
        return (u64)atomic64_read(&(counter)->packets);
}

static bool
ip_set_put_counter(struct sk_buff *skb, const struct ip_set_counter *counter)
{
        return nla_put_net64(skb, IPSET_ATTR_BYTES,
                             cpu_to_be64(ip_set_get_bytes(counter)),
                             IPSET_ATTR_PAD) ||
               nla_put_net64(skb, IPSET_ATTR_PACKETS,
                             cpu_to_be64(ip_set_get_packets(counter)),
                             IPSET_ATTR_PAD);
}

static bool
ip_set_put_skbinfo(struct sk_buff *skb, const struct ip_set_skbinfo *skbinfo)
{
        /* Send nonzero parameters only */
        return ((skbinfo->skbmark || skbinfo->skbmarkmask) &&
                nla_put_net64(skb, IPSET_ATTR_SKBMARK,
                              cpu_to_be64((u64)skbinfo->skbmark << 32 |
                                          skbinfo->skbmarkmask),
                              IPSET_ATTR_PAD)) ||
               (skbinfo->skbprio &&
                nla_put_net32(skb, IPSET_ATTR_SKBPRIO,
                              cpu_to_be32(skbinfo->skbprio))) ||
               (skbinfo->skbqueue &&
                nla_put_net16(skb, IPSET_ATTR_SKBQUEUE,
                              cpu_to_be16(skbinfo->skbqueue)));
}

int
ip_set_put_extensions(struct sk_buff *skb, const struct ip_set *set,
                      const void *e, bool active)
{
        if (SET_WITH_TIMEOUT(set)) {
                unsigned long *timeout = ext_timeout(e, set);

                if (nla_put_net32(skb, IPSET_ATTR_TIMEOUT,
                        htonl(active ? ip_set_timeout_get(timeout)
                                : *timeout)))
                        return -EMSGSIZE;
        }
        if (SET_WITH_COUNTER(set) &&
            ip_set_put_counter(skb, ext_counter(e, set)))
                return -EMSGSIZE;
        if (SET_WITH_COMMENT(set) &&
            ip_set_put_comment(skb, ext_comment(e, set)))
                return -EMSGSIZE;
        if (SET_WITH_SKBINFO(set) &&
            ip_set_put_skbinfo(skb, ext_skbinfo(e, set)))
                return -EMSGSIZE;
        return 0;
}
EXPORT_SYMBOL_GPL(ip_set_put_extensions);

static bool
ip_set_match_counter(u64 counter, u64 match, u8 op)
{
        switch (op) {
        case IPSET_COUNTER_NONE:
                return true;
        case IPSET_COUNTER_EQ:
                return counter == match;
        case IPSET_COUNTER_NE:
                return counter != match;
        case IPSET_COUNTER_LT:
                return counter < match;
        case IPSET_COUNTER_GT:
                return counter > match;
        }
        return false;
}

static void
ip_set_add_bytes(u64 bytes, struct ip_set_counter *counter)
{
        atomic64_add((long long)bytes, &(counter)->bytes);
}

static void
ip_set_add_packets(u64 packets, struct ip_set_counter *counter)
{
        atomic64_add((long long)packets, &(counter)->packets);
}

static void
ip_set_update_counter(struct ip_set_counter *counter,
                      const struct ip_set_ext *ext, u32 flags)
{
        if (ext->packets != ULLONG_MAX &&
            !(flags & IPSET_FLAG_SKIP_COUNTER_UPDATE)) {
                ip_set_add_bytes(ext->bytes, counter);
                ip_set_add_packets(ext->packets, counter);
        }
}

static void
ip_set_get_skbinfo(struct ip_set_skbinfo *skbinfo,
                   const struct ip_set_ext *ext,
                   struct ip_set_ext *mext, u32 flags)
{
        mext->skbinfo = *skbinfo;
}

bool
ip_set_match_extensions(struct ip_set *set, const struct ip_set_ext *ext,
                        struct ip_set_ext *mext, u32 flags, void *data)
{
        if (SET_WITH_TIMEOUT(set) &&
            ip_set_timeout_expired(ext_timeout(data, set)))
                return false;
        if (SET_WITH_COUNTER(set)) {
                struct ip_set_counter *counter = ext_counter(data, set);

                ip_set_update_counter(counter, ext, flags);

                if (flags & IPSET_FLAG_MATCH_COUNTERS &&
                    !(ip_set_match_counter(ip_set_get_packets(counter),
                                mext->packets, mext->packets_op) &&
                      ip_set_match_counter(ip_set_get_bytes(counter),
                                mext->bytes, mext->bytes_op)))
                        return false;
        }
        if (SET_WITH_SKBINFO(set))
                ip_set_get_skbinfo(ext_skbinfo(data, set),
                                   ext, mext, flags);
        return true;
}
EXPORT_SYMBOL_GPL(ip_set_match_extensions);

/* Creating/destroying/renaming/swapping affect the existence and
 * the properties of a set. All of these can be executed from userspace
 * only and serialized by the nfnl mutex indirectly from nfnetlink.
 *
 * Sets are identified by their index in ip_set_list and the index
 * is used by the external references (set/SET netfilter modules).
 *
 * The set behind an index may change by swapping only, from userspace.
 */

static void
__ip_set_get(struct ip_set *set)
{
        write_lock_bh(&ip_set_ref_lock);
        set->ref++;
        write_unlock_bh(&ip_set_ref_lock);
}

static void
__ip_set_put(struct ip_set *set)
{
        write_lock_bh(&ip_set_ref_lock);
        BUG_ON(set->ref == 0);
        set->ref--;
        write_unlock_bh(&ip_set_ref_lock);
}

/* set->ref can be swapped out by ip_set_swap, netlink events (like dump) need
 * a separate reference counter
 */
static void
__ip_set_put_netlink(struct ip_set *set)
{
        write_lock_bh(&ip_set_ref_lock);
        BUG_ON(set->ref_netlink == 0);
        set->ref_netlink--;
        write_unlock_bh(&ip_set_ref_lock);
}

/* Add, del and test set entries from kernel.
 *
 * The set behind the index must exist and must be referenced
 * so it can't be destroyed (or changed) under our foot.
 */

static struct ip_set *
ip_set_rcu_get(struct net *net, ip_set_id_t index)
{
        struct ip_set *set;
        struct ip_set_net *inst = ip_set_pernet(net);

        rcu_read_lock();
        /* ip_set_list itself needs to be protected */
        set = rcu_dereference(inst->ip_set_list)[index];
        rcu_read_unlock();

        return set;
}

static inline void
ip_set_lock(struct ip_set *set)
{
        if (!set->variant->region_lock)
                spin_lock_bh(&set->lock);
}

static inline void
ip_set_unlock(struct ip_set *set)
{
        if (!set->variant->region_lock)
                spin_unlock_bh(&set->lock);
}

int
ip_set_test(ip_set_id_t index, const struct sk_buff *skb,
            const struct xt_action_param *par, struct ip_set_adt_opt *opt)
{
        struct ip_set *set = ip_set_rcu_get(xt_net(par), index);
        int ret = 0;

        BUG_ON(!set);
        pr_debug("set %s, index %u\n", set->name, index);

        if (opt->dim < set->type->dimension ||
            !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
                return 0;

        rcu_read_lock_bh();
        ret = set->variant->kadt(set, skb, par, IPSET_TEST, opt);
        rcu_read_unlock_bh();

        if (ret == -EAGAIN) {
                /* Type requests element to be completed */
                pr_debug("element must be completed, ADD is triggered\n");
                ip_set_lock(set);
                set->variant->kadt(set, skb, par, IPSET_ADD, opt);
                ip_set_unlock(set);
                ret = 1;
        } else {
                /* --return-nomatch: invert matched element */
                if ((opt->cmdflags & IPSET_FLAG_RETURN_NOMATCH) &&
                    (set->type->features & IPSET_TYPE_NOMATCH) &&
                    (ret > 0 || ret == -ENOTEMPTY))
                        ret = -ret;
        }

        /* Convert error codes to nomatch */
        return (ret < 0 ? 0 : ret);
}
EXPORT_SYMBOL_GPL(ip_set_test);

int
ip_set_add(ip_set_id_t index, const struct sk_buff *skb,
           const struct xt_action_param *par, struct ip_set_adt_opt *opt)
{
        struct ip_set *set = ip_set_rcu_get(xt_net(par), index);
        int ret;

        BUG_ON(!set);
        pr_debug("set %s, index %u\n", set->name, index);

        if (opt->dim < set->type->dimension ||
            !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
                return -IPSET_ERR_TYPE_MISMATCH;

        ip_set_lock(set);
        ret = set->variant->kadt(set, skb, par, IPSET_ADD, opt);
        ip_set_unlock(set);

        return ret;
}
EXPORT_SYMBOL_GPL(ip_set_add);

int
ip_set_del(ip_set_id_t index, const struct sk_buff *skb,
           const struct xt_action_param *par, struct ip_set_adt_opt *opt)
{
        struct ip_set *set = ip_set_rcu_get(xt_net(par), index);
        int ret = 0;

        BUG_ON(!set);
        pr_debug("set %s, index %u\n", set->name, index);

        if (opt->dim < set->type->dimension ||
            !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
                return -IPSET_ERR_TYPE_MISMATCH;

        ip_set_lock(set);
        ret = set->variant->kadt(set, skb, par, IPSET_DEL, opt);
        ip_set_unlock(set);

        return ret;
}
EXPORT_SYMBOL_GPL(ip_set_del);

/* Find set by name, reference it once. The reference makes sure the
 * thing pointed to, does not go away under our feet.
 *
 */
ip_set_id_t
ip_set_get_byname(struct net *net, const char *name, struct ip_set **set)
{
        ip_set_id_t i, index = IPSET_INVALID_ID;
        struct ip_set *s;
        struct ip_set_net *inst = ip_set_pernet(net);

        rcu_read_lock();
        for (i = 0; i < inst->ip_set_max; i++) {
                s = rcu_dereference(inst->ip_set_list)[i];
                if (s && STRNCMP(s->name, name)) {
                        __ip_set_get(s);
                        index = i;
                        *set = s;
                        break;
                }
        }
        rcu_read_unlock();

        return index;
}
EXPORT_SYMBOL_GPL(ip_set_get_byname);

/* If the given set pointer points to a valid set, decrement
 * reference count by 1. The caller shall not assume the index
 * to be valid, after calling this function.
 *
 */

static void
__ip_set_put_byindex(struct ip_set_net *inst, ip_set_id_t index)
{
        struct ip_set *set;

        rcu_read_lock();
        set = rcu_dereference(inst->ip_set_list)[index];
        if (set)
                __ip_set_put(set);
        rcu_read_unlock();
}

void
ip_set_put_byindex(struct net *net, ip_set_id_t index)
{
        struct ip_set_net *inst = ip_set_pernet(net);

        __ip_set_put_byindex(inst, index);
}
EXPORT_SYMBOL_GPL(ip_set_put_byindex);

/* Get the name of a set behind a set index.
 * Set itself is protected by RCU, but its name isn't: to protect against
 * renaming, grab ip_set_ref_lock as reader (see ip_set_rename()) and copy the
 * name.
 */
void
ip_set_name_byindex(struct net *net, ip_set_id_t index, char *name)
{
        struct ip_set *set = ip_set_rcu_get(net, index);

        BUG_ON(!set);

        read_lock_bh(&ip_set_ref_lock);
        strncpy(name, set->name, IPSET_MAXNAMELEN);
        read_unlock_bh(&ip_set_ref_lock);
}
EXPORT_SYMBOL_GPL(ip_set_name_byindex);

/* Routines to call by external subsystems, which do not
 * call nfnl_lock for us.
 */

/* Find set by index, reference it once. The reference makes sure the
 * thing pointed to, does not go away under our feet.
 *
 * The nfnl mutex is used in the function.
 */
ip_set_id_t
ip_set_nfnl_get_byindex(struct net *net, ip_set_id_t index)
{
        struct ip_set *set;
        struct ip_set_net *inst = ip_set_pernet(net);

        if (index >= inst->ip_set_max)
                return IPSET_INVALID_ID;

        nfnl_lock(NFNL_SUBSYS_IPSET);
        set = ip_set(inst, index);
        if (set)
                __ip_set_get(set);
        else
                index = IPSET_INVALID_ID;
        nfnl_unlock(NFNL_SUBSYS_IPSET);

        return index;
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_get_byindex);

/* If the given set pointer points to a valid set, decrement
 * reference count by 1. The caller shall not assume the index
 * to be valid, after calling this function.
 *
 * The nfnl mutex is used in the function.
 */
void
ip_set_nfnl_put(struct net *net, ip_set_id_t index)
{
        struct ip_set *set;
        struct ip_set_net *inst = ip_set_pernet(net);

        nfnl_lock(NFNL_SUBSYS_IPSET);
        if (!inst->is_deleted) { /* already deleted from ip_set_net_exit() */
                set = ip_set(inst, index);
                if (set)
                        __ip_set_put(set);
        }
        nfnl_unlock(NFNL_SUBSYS_IPSET);
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_put);

/* Communication protocol with userspace over netlink.
 *
 * The commands are serialized by the nfnl mutex.
 */

static inline u8 protocol(const struct nlattr * const tb[])
{
        return nla_get_u8(tb[IPSET_ATTR_PROTOCOL]);
}

static inline bool
protocol_failed(const struct nlattr * const tb[])
{
        return !tb[IPSET_ATTR_PROTOCOL] || protocol(tb) != IPSET_PROTOCOL;
}

static inline bool
protocol_min_failed(const struct nlattr * const tb[])
{
        return !tb[IPSET_ATTR_PROTOCOL] || protocol(tb) < IPSET_PROTOCOL_MIN;
}

static inline u32
flag_exist(const struct nlmsghdr *nlh)
{
        return nlh->nlmsg_flags & NLM_F_EXCL ? 0 : IPSET_FLAG_EXIST;
}

static struct nlmsghdr *
start_msg(struct sk_buff *skb, u32 portid, u32 seq, unsigned int flags,
          enum ipset_cmd cmd)
{
        return nfnl_msg_put(skb, portid, seq,
                            nfnl_msg_type(NFNL_SUBSYS_IPSET, cmd), flags,
                            NFPROTO_IPV4, NFNETLINK_V0, 0);
}

/* Create a set */

static const struct nla_policy ip_set_create_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_SETNAME]    = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
        [IPSET_ATTR_TYPENAME]   = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1},
        [IPSET_ATTR_REVISION]   = { .type = NLA_U8 },
        [IPSET_ATTR_FAMILY]     = { .type = NLA_U8 },
        [IPSET_ATTR_DATA]       = { .type = NLA_NESTED },
};

static struct ip_set *
find_set_and_id(struct ip_set_net *inst, const char *name, ip_set_id_t *id)
{
        struct ip_set *set = NULL;
        ip_set_id_t i;

        *id = IPSET_INVALID_ID;
        for (i = 0; i < inst->ip_set_max; i++) {
                set = ip_set(inst, i);
                if (set && STRNCMP(set->name, name)) {
                        *id = i;
                        break;
                }
        }
        return (*id == IPSET_INVALID_ID ? NULL : set);
}

static inline struct ip_set *
find_set(struct ip_set_net *inst, const char *name)
{
        ip_set_id_t id;

        return find_set_and_id(inst, name, &id);
}

static int
find_free_id(struct ip_set_net *inst, const char *name, ip_set_id_t *index,
             struct ip_set **set)
{
        struct ip_set *s;
        ip_set_id_t i;

        *index = IPSET_INVALID_ID;
        for (i = 0;  i < inst->ip_set_max; i++) {
                s = ip_set(inst, i);
                if (!s) {
                        if (*index == IPSET_INVALID_ID)
                                *index = i;
                } else if (STRNCMP(name, s->name)) {
                        /* Name clash */
                        *set = s;
                        return -EEXIST;
                }
        }
        if (*index == IPSET_INVALID_ID)
                /* No free slot remained */
                return -IPSET_ERR_MAX_SETS;
        return 0;
}

static int ip_set_none(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        return -EOPNOTSUPP;
}

static int ip_set_create(struct sk_buff *skb, const struct nfnl_info *info,
                         const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *set, *clash = NULL;
        ip_set_id_t index = IPSET_INVALID_ID;
        struct nlattr *tb[IPSET_ATTR_CREATE_MAX + 1] = {};
        const char *name, *typename;
        u8 family, revision;
        u32 flags = flag_exist(info->nlh);
        int ret = 0;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME] ||
                     !attr[IPSET_ATTR_TYPENAME] ||
                     !attr[IPSET_ATTR_REVISION] ||
                     !attr[IPSET_ATTR_FAMILY] ||
                     (attr[IPSET_ATTR_DATA] &&
                      !flag_nested(attr[IPSET_ATTR_DATA]))))
                return -IPSET_ERR_PROTOCOL;

        name = nla_data(attr[IPSET_ATTR_SETNAME]);
        typename = nla_data(attr[IPSET_ATTR_TYPENAME]);
        family = nla_get_u8(attr[IPSET_ATTR_FAMILY]);
        revision = nla_get_u8(attr[IPSET_ATTR_REVISION]);
        pr_debug("setname: %s, typename: %s, family: %s, revision: %u\n",
                 name, typename, family_name(family), revision);

        /* First, and without any locks, allocate and initialize
         * a normal base set structure.
         */
        set = kzalloc(sizeof(*set), GFP_KERNEL);
        if (!set)
                return -ENOMEM;
        spin_lock_init(&set->lock);
        strlcpy(set->name, name, IPSET_MAXNAMELEN);
        set->family = family;
        set->revision = revision;

        /* Next, check that we know the type, and take
         * a reference on the type, to make sure it stays available
         * while constructing our new set.
         *
         * After referencing the type, we try to create the type
         * specific part of the set without holding any locks.
         */
        ret = find_set_type_get(typename, family, revision, &set->type);
        if (ret)
                goto out;

        /* Without holding any locks, create private part. */
        if (attr[IPSET_ATTR_DATA] &&
            nla_parse_nested(tb, IPSET_ATTR_CREATE_MAX, attr[IPSET_ATTR_DATA],
                             set->type->create_policy, NULL)) {
                ret = -IPSET_ERR_PROTOCOL;
                goto put_out;
        }
        /* Set create flags depending on the type revision */
        set->flags |= set->type->create_flags[revision];

        ret = set->type->create(info->net, set, tb, flags);
        if (ret != 0)
                goto put_out;

        /* BTW, ret==0 here. */

        /* Here, we have a valid, constructed set and we are protected
         * by the nfnl mutex. Find the first free index in ip_set_list
         * and check clashing.
         */
        ret = find_free_id(inst, set->name, &index, &clash);
        if (ret == -EEXIST) {
                /* If this is the same set and requested, ignore error */
                if ((flags & IPSET_FLAG_EXIST) &&
                    STRNCMP(set->type->name, clash->type->name) &&
                    set->type->family == clash->type->family &&
                    set->type->revision_min == clash->type->revision_min &&
                    set->type->revision_max == clash->type->revision_max &&
                    set->variant->same_set(set, clash))
                        ret = 0;
                goto cleanup;
        } else if (ret == -IPSET_ERR_MAX_SETS) {
                struct ip_set **list, **tmp;
                ip_set_id_t i = inst->ip_set_max + IP_SET_INC;

                if (i < inst->ip_set_max || i == IPSET_INVALID_ID)
                        /* Wraparound */
                        goto cleanup;

                list = kvcalloc(i, sizeof(struct ip_set *), GFP_KERNEL);
                if (!list)
                        goto cleanup;
                /* nfnl mutex is held, both lists are valid */
                tmp = ip_set_dereference(inst->ip_set_list);
                memcpy(list, tmp, sizeof(struct ip_set *) * inst->ip_set_max);
                rcu_assign_pointer(inst->ip_set_list, list);
                /* Make sure all current packets have passed through */
                synchronize_net();
                /* Use new list */
                index = inst->ip_set_max;
                inst->ip_set_max = i;
                kvfree(tmp);
                ret = 0;
        } else if (ret) {
                goto cleanup;
        }

        /* Finally! Add our shiny new set to the list, and be done. */
        pr_debug("create: '%s' created with index %u!\n", set->name, index);
        ip_set(inst, index) = set;

        return ret;

cleanup:
        set->variant->destroy(set);
put_out:
        module_put(set->type->me);
out:
        kfree(set);
        return ret;
}

/* Destroy sets */

static const struct nla_policy
ip_set_setname_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_SETNAME]    = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
};

static void
ip_set_destroy_set(struct ip_set *set)
{
        pr_debug("set: %s\n",  set->name);

        /* Must call it without holding any lock */
        set->variant->destroy(set);
        module_put(set->type->me);
        kfree(set);
}

static int ip_set_destroy(struct sk_buff *skb, const struct nfnl_info *info,
                          const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *s;
        ip_set_id_t i;
        int ret = 0;

        if (unlikely(protocol_min_failed(attr)))
                return -IPSET_ERR_PROTOCOL;

        /* Must wait for flush to be really finished in list:set */
        rcu_barrier();

        /* Commands are serialized and references are
         * protected by the ip_set_ref_lock.
         * External systems (i.e. xt_set) must call
         * ip_set_put|get_nfnl_* functions, that way we
         * can safely check references here.
         *
         * list:set timer can only decrement the reference
         * counter, so if it's already zero, we can proceed
         * without holding the lock.
         */
        read_lock_bh(&ip_set_ref_lock);
        if (!attr[IPSET_ATTR_SETNAME]) {
                for (i = 0; i < inst->ip_set_max; i++) {
                        s = ip_set(inst, i);
                        if (s && (s->ref || s->ref_netlink)) {
                                ret = -IPSET_ERR_BUSY;
                                goto out;
                        }
                }
                inst->is_destroyed = true;
                read_unlock_bh(&ip_set_ref_lock);
                for (i = 0; i < inst->ip_set_max; i++) {
                        s = ip_set(inst, i);
                        if (s) {
                                ip_set(inst, i) = NULL;
                                ip_set_destroy_set(s);
                        }
                }
                /* Modified by ip_set_destroy() only, which is serialized */
                inst->is_destroyed = false;
        } else {
                u32 flags = flag_exist(info->nlh);
                s = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME]),
                                    &i);
                if (!s) {
                        if (!(flags & IPSET_FLAG_EXIST))
                                ret = -ENOENT;
                        goto out;
                } else if (s->ref || s->ref_netlink) {
                        ret = -IPSET_ERR_BUSY;
                        goto out;
                }
                ip_set(inst, i) = NULL;
                read_unlock_bh(&ip_set_ref_lock);

                ip_set_destroy_set(s);
        }
        return 0;
out:
        read_unlock_bh(&ip_set_ref_lock);
        return ret;
}

/* Flush sets */

static void
ip_set_flush_set(struct ip_set *set)
{
        pr_debug("set: %s\n",  set->name);

        ip_set_lock(set);
        set->variant->flush(set);
        ip_set_unlock(set);
}

static int ip_set_flush(struct sk_buff *skb, const struct nfnl_info *info,
                        const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *s;
        ip_set_id_t i;

        if (unlikely(protocol_min_failed(attr)))
                return -IPSET_ERR_PROTOCOL;

        if (!attr[IPSET_ATTR_SETNAME]) {
                for (i = 0; i < inst->ip_set_max; i++) {
                        s = ip_set(inst, i);
                        if (s)
                                ip_set_flush_set(s);
                }
        } else {
                s = find_set(inst, nla_data(attr[IPSET_ATTR_SETNAME]));
                if (!s)
                        return -ENOENT;

                ip_set_flush_set(s);
        }

        return 0;
}

/* Rename a set */

static const struct nla_policy
ip_set_setname2_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_SETNAME]    = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
        [IPSET_ATTR_SETNAME2]   = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
};

static int ip_set_rename(struct sk_buff *skb, const struct nfnl_info *info,
                         const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *set, *s;
        const char *name2;
        ip_set_id_t i;
        int ret = 0;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME] ||
                     !attr[IPSET_ATTR_SETNAME2]))
                return -IPSET_ERR_PROTOCOL;

        set = find_set(inst, nla_data(attr[IPSET_ATTR_SETNAME]));
        if (!set)
                return -ENOENT;

        write_lock_bh(&ip_set_ref_lock);
        if (set->ref != 0 || set->ref_netlink != 0) {
                ret = -IPSET_ERR_REFERENCED;
                goto out;
        }

        name2 = nla_data(attr[IPSET_ATTR_SETNAME2]);
        for (i = 0; i < inst->ip_set_max; i++) {
                s = ip_set(inst, i);
                if (s && STRNCMP(s->name, name2)) {
                        ret = -IPSET_ERR_EXIST_SETNAME2;
                        goto out;
                }
        }
        strncpy(set->name, name2, IPSET_MAXNAMELEN);

out:
        write_unlock_bh(&ip_set_ref_lock);
        return ret;
}

/* Swap two sets so that name/index points to the other.
 * References and set names are also swapped.
 *
 * The commands are serialized by the nfnl mutex and references are
 * protected by the ip_set_ref_lock. The kernel interfaces
 * do not hold the mutex but the pointer settings are atomic
 * so the ip_set_list always contains valid pointers to the sets.
 */

static int ip_set_swap(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *from, *to;
        ip_set_id_t from_id, to_id;
        char from_name[IPSET_MAXNAMELEN];

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME] ||
                     !attr[IPSET_ATTR_SETNAME2]))
                return -IPSET_ERR_PROTOCOL;

        from = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME]),
                               &from_id);
        if (!from)
                return -ENOENT;

        to = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME2]),
                             &to_id);
        if (!to)
                return -IPSET_ERR_EXIST_SETNAME2;

        /* Features must not change.
         * Not an artifical restriction anymore, as we must prevent
         * possible loops created by swapping in setlist type of sets.
         */
        if (!(from->type->features == to->type->features &&
              from->family == to->family))
                return -IPSET_ERR_TYPE_MISMATCH;

        write_lock_bh(&ip_set_ref_lock);

        if (from->ref_netlink || to->ref_netlink) {
                write_unlock_bh(&ip_set_ref_lock);
                return -EBUSY;
        }

        strncpy(from_name, from->name, IPSET_MAXNAMELEN);
        strncpy(from->name, to->name, IPSET_MAXNAMELEN);
        strncpy(to->name, from_name, IPSET_MAXNAMELEN);

        swap(from->ref, to->ref);
        ip_set(inst, from_id) = to;
        ip_set(inst, to_id) = from;
        write_unlock_bh(&ip_set_ref_lock);

        return 0;
}

/* List/save set data */

#define DUMP_INIT       0
#define DUMP_ALL        1
#define DUMP_ONE        2
#define DUMP_LAST       3

#define DUMP_TYPE(arg)          (((u32)(arg)) & 0x0000FFFF)
#define DUMP_FLAGS(arg)         (((u32)(arg)) >> 16)

int
ip_set_put_flags(struct sk_buff *skb, struct ip_set *set)
{
        u32 cadt_flags = 0;

        if (SET_WITH_TIMEOUT(set))
                if (unlikely(nla_put_net32(skb, IPSET_ATTR_TIMEOUT,
                                           htonl(set->timeout))))
                        return -EMSGSIZE;
        if (SET_WITH_COUNTER(set))
                cadt_flags |= IPSET_FLAG_WITH_COUNTERS;
        if (SET_WITH_COMMENT(set))
                cadt_flags |= IPSET_FLAG_WITH_COMMENT;
        if (SET_WITH_SKBINFO(set))
                cadt_flags |= IPSET_FLAG_WITH_SKBINFO;
        if (SET_WITH_FORCEADD(set))
                cadt_flags |= IPSET_FLAG_WITH_FORCEADD;

        if (!cadt_flags)
                return 0;
        return nla_put_net32(skb, IPSET_ATTR_CADT_FLAGS, htonl(cadt_flags));
}
EXPORT_SYMBOL_GPL(ip_set_put_flags);

static int
ip_set_dump_done(struct netlink_callback *cb)
{
        if (cb->args[IPSET_CB_ARG0]) {
                struct ip_set_net *inst =
                        (struct ip_set_net *)cb->args[IPSET_CB_NET];
                ip_set_id_t index = (ip_set_id_t)cb->args[IPSET_CB_INDEX];
                struct ip_set *set = ip_set_ref_netlink(inst, index);

                if (set->variant->uref)
                        set->variant->uref(set, cb, false);
                pr_debug("release set %s\n", set->name);
                __ip_set_put_netlink(set);
        }
        return 0;
}

static inline void
dump_attrs(struct nlmsghdr *nlh)
{
        const struct nlattr *attr;
        int rem;

        pr_debug("dump nlmsg\n");
        nlmsg_for_each_attr(attr, nlh, sizeof(struct nfgenmsg), rem) {
                pr_debug("type: %u, len %u\n", nla_type(attr), attr->nla_len);
        }
}

static const struct nla_policy
ip_set_dump_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_SETNAME]    = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
        [IPSET_ATTR_FLAGS]      = { .type = NLA_U32 },
};

static int
ip_set_dump_start(struct netlink_callback *cb)
{
        struct nlmsghdr *nlh = nlmsg_hdr(cb->skb);
        int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
        struct nlattr *cda[IPSET_ATTR_CMD_MAX + 1];
        struct nlattr *attr = (void *)nlh + min_len;
        struct sk_buff *skb = cb->skb;
        struct ip_set_net *inst = ip_set_pernet(sock_net(skb->sk));
        u32 dump_type;
        int ret;

        ret = nla_parse(cda, IPSET_ATTR_CMD_MAX, attr,
                        nlh->nlmsg_len - min_len,
                        ip_set_dump_policy, NULL);
        if (ret)
                goto error;

        cb->args[IPSET_CB_PROTO] = nla_get_u8(cda[IPSET_ATTR_PROTOCOL]);
        if (cda[IPSET_ATTR_SETNAME]) {
                ip_set_id_t index;
                struct ip_set *set;

                set = find_set_and_id(inst, nla_data(cda[IPSET_ATTR_SETNAME]),
                                      &index);
                if (!set) {
                        ret = -ENOENT;
                        goto error;
                }
                dump_type = DUMP_ONE;
                cb->args[IPSET_CB_INDEX] = index;
        } else {
                dump_type = DUMP_ALL;
        }

        if (cda[IPSET_ATTR_FLAGS]) {
                u32 f = ip_set_get_h32(cda[IPSET_ATTR_FLAGS]);

                dump_type |= (f << 16);
        }
        cb->args[IPSET_CB_NET] = (unsigned long)inst;
        cb->args[IPSET_CB_DUMP] = dump_type;

        return 0;

error:
        /* We have to create and send the error message manually :-( */
        if (nlh->nlmsg_flags & NLM_F_ACK) {
                netlink_ack(cb->skb, nlh, ret, NULL);
        }
        return ret;
}

static int
ip_set_dump_do(struct sk_buff *skb, struct netlink_callback *cb)
{
        ip_set_id_t index = IPSET_INVALID_ID, max;
        struct ip_set *set = NULL;
        struct nlmsghdr *nlh = NULL;
        unsigned int flags = NETLINK_CB(cb->skb).portid ? NLM_F_MULTI : 0;
        struct ip_set_net *inst = ip_set_pernet(sock_net(skb->sk));
        u32 dump_type, dump_flags;
        bool is_destroyed;
        int ret = 0;

        if (!cb->args[IPSET_CB_DUMP])
                return -EINVAL;

        if (cb->args[IPSET_CB_INDEX] >= inst->ip_set_max)
                goto out;

        dump_type = DUMP_TYPE(cb->args[IPSET_CB_DUMP]);
        dump_flags = DUMP_FLAGS(cb->args[IPSET_CB_DUMP]);
        max = dump_type == DUMP_ONE ? cb->args[IPSET_CB_INDEX] + 1
                                    : inst->ip_set_max;
dump_last:
        pr_debug("dump type, flag: %u %u index: %ld\n",
                 dump_type, dump_flags, cb->args[IPSET_CB_INDEX]);
        for (; cb->args[IPSET_CB_INDEX] < max; cb->args[IPSET_CB_INDEX]++) {
                index = (ip_set_id_t)cb->args[IPSET_CB_INDEX];
                write_lock_bh(&ip_set_ref_lock);
                set = ip_set(inst, index);
                is_destroyed = inst->is_destroyed;
                if (!set || is_destroyed) {
                        write_unlock_bh(&ip_set_ref_lock);
                        if (dump_type == DUMP_ONE) {
                                ret = -ENOENT;
                                goto out;
                        }
                        if (is_destroyed) {
                                /* All sets are just being destroyed */
                                ret = 0;
                                goto out;
                        }
                        continue;
                }
                /* When dumping all sets, we must dump "sorted"
                 * so that lists (unions of sets) are dumped last.
                 */
                if (dump_type != DUMP_ONE &&
                    ((dump_type == DUMP_ALL) ==
                     !!(set->type->features & IPSET_DUMP_LAST))) {
                        write_unlock_bh(&ip_set_ref_lock);
                        continue;
                }
                pr_debug("List set: %s\n", set->name);
                if (!cb->args[IPSET_CB_ARG0]) {
                        /* Start listing: make sure set won't be destroyed */
                        pr_debug("reference set\n");
                        set->ref_netlink++;
                }
                write_unlock_bh(&ip_set_ref_lock);
                nlh = start_msg(skb, NETLINK_CB(cb->skb).portid,
                                cb->nlh->nlmsg_seq, flags,
                                IPSET_CMD_LIST);
                if (!nlh) {
                        ret = -EMSGSIZE;
                        goto release_refcount;
                }
                if (nla_put_u8(skb, IPSET_ATTR_PROTOCOL,
                               cb->args[IPSET_CB_PROTO]) ||
                    nla_put_string(skb, IPSET_ATTR_SETNAME, set->name))
                        goto nla_put_failure;
                if (dump_flags & IPSET_FLAG_LIST_SETNAME)
                        goto next_set;
                switch (cb->args[IPSET_CB_ARG0]) {
                case 0:
                        /* Core header data */
                        if (nla_put_string(skb, IPSET_ATTR_TYPENAME,
                                           set->type->name) ||
                            nla_put_u8(skb, IPSET_ATTR_FAMILY,
                                       set->family) ||
                            nla_put_u8(skb, IPSET_ATTR_REVISION,
                                       set->revision))
                                goto nla_put_failure;
                        if (cb->args[IPSET_CB_PROTO] > IPSET_PROTOCOL_MIN &&
                            nla_put_net16(skb, IPSET_ATTR_INDEX, htons(index)))
                                goto nla_put_failure;
                        ret = set->variant->head(set, skb);
                        if (ret < 0)
                                goto release_refcount;
                        if (dump_flags & IPSET_FLAG_LIST_HEADER)
                                goto next_set;
                        if (set->variant->uref)
                                set->variant->uref(set, cb, true);
                        fallthrough;
                default:
                        ret = set->variant->list(set, skb, cb);
                        if (!cb->args[IPSET_CB_ARG0])
                                /* Set is done, proceed with next one */
                                goto next_set;
                        goto release_refcount;
                }
        }
        /* If we dump all sets, continue with dumping last ones */
        if (dump_type == DUMP_ALL) {
                dump_type = DUMP_LAST;
                cb->args[IPSET_CB_DUMP] = dump_type | (dump_flags << 16);
                cb->args[IPSET_CB_INDEX] = 0;
                if (set && set->variant->uref)
                        set->variant->uref(set, cb, false);
                goto dump_last;
        }
        goto out;

nla_put_failure:
        ret = -EFAULT;
next_set:
        if (dump_type == DUMP_ONE)
                cb->args[IPSET_CB_INDEX] = IPSET_INVALID_ID;
        else
                cb->args[IPSET_CB_INDEX]++;
release_refcount:
        /* If there was an error or set is done, release set */
        if (ret || !cb->args[IPSET_CB_ARG0]) {
                set = ip_set_ref_netlink(inst, index);
                if (set->variant->uref)
                        set->variant->uref(set, cb, false);
                pr_debug("release set %s\n", set->name);
                __ip_set_put_netlink(set);
                cb->args[IPSET_CB_ARG0] = 0;
        }
out:
        if (nlh) {
                nlmsg_end(skb, nlh);
                pr_debug("nlmsg_len: %u\n", nlh->nlmsg_len);
                dump_attrs(nlh);
        }

        return ret < 0 ? ret : skb->len;
}

static int ip_set_dump(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        if (unlikely(protocol_min_failed(attr)))
                return -IPSET_ERR_PROTOCOL;

        {
                struct netlink_dump_control c = {
                        .start = ip_set_dump_start,
                        .dump = ip_set_dump_do,
                        .done = ip_set_dump_done,
                };
                return netlink_dump_start(info->sk, skb, info->nlh, &c);
        }
}

/* Add, del and test */

static const struct nla_policy ip_set_adt_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_SETNAME]    = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
        [IPSET_ATTR_LINENO]     = { .type = NLA_U32 },
        [IPSET_ATTR_DATA]       = { .type = NLA_NESTED },
        [IPSET_ATTR_ADT]        = { .type = NLA_NESTED },
};

static int
call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb,
        struct ip_set *set, struct nlattr *tb[], enum ipset_adt adt,
        u32 flags, bool use_lineno)
{
        int ret;
        u32 lineno = 0;
        bool eexist = flags & IPSET_FLAG_EXIST, retried = false;

        do {
                ip_set_lock(set);
                ret = set->variant->uadt(set, tb, adt, &lineno, flags, retried);
                ip_set_unlock(set);
                retried = true;
        } while (ret == -EAGAIN &&
                 set->variant->resize &&
                 (ret = set->variant->resize(set, retried)) == 0);

        if (!ret || (ret == -IPSET_ERR_EXIST && eexist))
                return 0;
        if (lineno && use_lineno) {
                /* Error in restore/batch mode: send back lineno */
                struct nlmsghdr *rep, *nlh = nlmsg_hdr(skb);
                struct sk_buff *skb2;
                struct nlmsgerr *errmsg;
                size_t payload = min(SIZE_MAX,
                                     sizeof(*errmsg) + nlmsg_len(nlh));
                int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
                struct nlattr *cda[IPSET_ATTR_CMD_MAX + 1];
                struct nlattr *cmdattr;
                u32 *errline;

                skb2 = nlmsg_new(payload, GFP_KERNEL);
                if (!skb2)
                        return -ENOMEM;
                rep = __nlmsg_put(skb2, NETLINK_CB(skb).portid,
                                  nlh->nlmsg_seq, NLMSG_ERROR, payload, 0);
                errmsg = nlmsg_data(rep);
                errmsg->error = ret;
                memcpy(&errmsg->msg, nlh, nlh->nlmsg_len);
                cmdattr = (void *)&errmsg->msg + min_len;

                ret = nla_parse(cda, IPSET_ATTR_CMD_MAX, cmdattr,
                                nlh->nlmsg_len - min_len, ip_set_adt_policy,
                                NULL);

                if (ret) {
                        nlmsg_free(skb2);
                        return ret;
                }
                errline = nla_data(cda[IPSET_ATTR_LINENO]);

                *errline = lineno;

                nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
                /* Signal netlink not to send its ACK/errmsg.  */
                return -EINTR;
        }

        return ret;
}

static int ip_set_ad(struct net *net, struct sock *ctnl,
                     struct sk_buff *skb,
                     enum ipset_adt adt,
                     const struct nlmsghdr *nlh,
                     const struct nlattr * const attr[],
                     struct netlink_ext_ack *extack)
{
        struct ip_set_net *inst = ip_set_pernet(net);
        struct ip_set *set;
        struct nlattr *tb[IPSET_ATTR_ADT_MAX + 1] = {};
        const struct nlattr *nla;
        u32 flags = flag_exist(nlh);
        bool use_lineno;
        int ret = 0;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME] ||
                     !((attr[IPSET_ATTR_DATA] != NULL) ^
                       (attr[IPSET_ATTR_ADT] != NULL)) ||
                     (attr[IPSET_ATTR_DATA] &&
                      !flag_nested(attr[IPSET_ATTR_DATA])) ||
                     (attr[IPSET_ATTR_ADT] &&
                      (!flag_nested(attr[IPSET_ATTR_ADT]) ||
                       !attr[IPSET_ATTR_LINENO]))))
                return -IPSET_ERR_PROTOCOL;

        set = find_set(inst, nla_data(attr[IPSET_ATTR_SETNAME]));
        if (!set)
                return -ENOENT;

        use_lineno = !!attr[IPSET_ATTR_LINENO];
        if (attr[IPSET_ATTR_DATA]) {
                if (nla_parse_nested(tb, IPSET_ATTR_ADT_MAX,
                                     attr[IPSET_ATTR_DATA],
                                     set->type->adt_policy, NULL))
                        return -IPSET_ERR_PROTOCOL;
                ret = call_ad(net, ctnl, skb, set, tb, adt, flags,
                              use_lineno);
        } else {
                int nla_rem;

                nla_for_each_nested(nla, attr[IPSET_ATTR_ADT], nla_rem) {
                        if (nla_type(nla) != IPSET_ATTR_DATA ||
                            !flag_nested(nla) ||
                            nla_parse_nested(tb, IPSET_ATTR_ADT_MAX, nla,
                                             set->type->adt_policy, NULL))
                                return -IPSET_ERR_PROTOCOL;
                        ret = call_ad(net, ctnl, skb, set, tb, adt,
                                      flags, use_lineno);
                        if (ret < 0)
                                return ret;
                }
        }
        return ret;
}

static int ip_set_uadd(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        return ip_set_ad(info->net, info->sk, skb,
                         IPSET_ADD, info->nlh, attr, info->extack);
}

static int ip_set_udel(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        return ip_set_ad(info->net, info->sk, skb,
                         IPSET_DEL, info->nlh, attr, info->extack);
}

static int ip_set_utest(struct sk_buff *skb, const struct nfnl_info *info,
                        const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct ip_set *set;
        struct nlattr *tb[IPSET_ATTR_ADT_MAX + 1] = {};
        int ret = 0;
        u32 lineno;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME] ||
                     !attr[IPSET_ATTR_DATA] ||
                     !flag_nested(attr[IPSET_ATTR_DATA])))
                return -IPSET_ERR_PROTOCOL;

        set = find_set(inst, nla_data(attr[IPSET_ATTR_SETNAME]));
        if (!set)
                return -ENOENT;

        if (nla_parse_nested(tb, IPSET_ATTR_ADT_MAX, attr[IPSET_ATTR_DATA],
                             set->type->adt_policy, NULL))
                return -IPSET_ERR_PROTOCOL;

        rcu_read_lock_bh();
        ret = set->variant->uadt(set, tb, IPSET_TEST, &lineno, 0, 0);
        rcu_read_unlock_bh();
        /* Userspace can't trigger element to be re-added */
        if (ret == -EAGAIN)
                ret = 1;

        return ret > 0 ? 0 : -IPSET_ERR_EXIST;
}

/* Get headed data of a set */

static int ip_set_header(struct sk_buff *skb, const struct nfnl_info *info,
                         const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        const struct ip_set *set;
        struct sk_buff *skb2;
        struct nlmsghdr *nlh2;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_SETNAME]))
                return -IPSET_ERR_PROTOCOL;

        set = find_set(inst, nla_data(attr[IPSET_ATTR_SETNAME]));
        if (!set)
                return -ENOENT;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb2)
                return -ENOMEM;

        nlh2 = start_msg(skb2, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, 0,
                         IPSET_CMD_HEADER);
        if (!nlh2)
                goto nlmsg_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, protocol(attr)) ||
            nla_put_string(skb2, IPSET_ATTR_SETNAME, set->name) ||
            nla_put_string(skb2, IPSET_ATTR_TYPENAME, set->type->name) ||
            nla_put_u8(skb2, IPSET_ATTR_FAMILY, set->family) ||
            nla_put_u8(skb2, IPSET_ATTR_REVISION, set->revision))
                goto nla_put_failure;
        nlmsg_end(skb2, nlh2);

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

nla_put_failure:
        nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
        kfree_skb(skb2);
        return -EMSGSIZE;
}

/* Get type data */

static const struct nla_policy ip_set_type_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_TYPENAME]   = { .type = NLA_NUL_STRING,
                                    .len = IPSET_MAXNAMELEN - 1 },
        [IPSET_ATTR_FAMILY]     = { .type = NLA_U8 },
};

static int ip_set_type(struct sk_buff *skb, const struct nfnl_info *info,
                       const struct nlattr * const attr[])
{
        struct sk_buff *skb2;
        struct nlmsghdr *nlh2;
        u8 family, min, max;
        const char *typename;
        int ret = 0;

        if (unlikely(protocol_min_failed(attr) ||
                     !attr[IPSET_ATTR_TYPENAME] ||
                     !attr[IPSET_ATTR_FAMILY]))
                return -IPSET_ERR_PROTOCOL;

        family = nla_get_u8(attr[IPSET_ATTR_FAMILY]);
        typename = nla_data(attr[IPSET_ATTR_TYPENAME]);
        ret = find_set_type_minmax(typename, family, &min, &max);
        if (ret)
                return ret;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb2)
                return -ENOMEM;

        nlh2 = start_msg(skb2, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, 0,
                         IPSET_CMD_TYPE);
        if (!nlh2)
                goto nlmsg_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, protocol(attr)) ||
            nla_put_string(skb2, IPSET_ATTR_TYPENAME, typename) ||
            nla_put_u8(skb2, IPSET_ATTR_FAMILY, family) ||
            nla_put_u8(skb2, IPSET_ATTR_REVISION, max) ||
            nla_put_u8(skb2, IPSET_ATTR_REVISION_MIN, min))
                goto nla_put_failure;
        nlmsg_end(skb2, nlh2);

        pr_debug("Send TYPE, nlmsg_len: %u\n", nlh2->nlmsg_len);
        return nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);

nla_put_failure:
        nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
        kfree_skb(skb2);
        return -EMSGSIZE;
}

/* Get protocol version */

static const struct nla_policy
ip_set_protocol_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
};

static int ip_set_protocol(struct sk_buff *skb, const struct nfnl_info *info,
                           const struct nlattr * const attr[])
{
        struct sk_buff *skb2;
        struct nlmsghdr *nlh2;

        if (unlikely(!attr[IPSET_ATTR_PROTOCOL]))
                return -IPSET_ERR_PROTOCOL;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb2)
                return -ENOMEM;

        nlh2 = start_msg(skb2, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, 0,
                         IPSET_CMD_PROTOCOL);
        if (!nlh2)
                goto nlmsg_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, IPSET_PROTOCOL))
                goto nla_put_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL_MIN, IPSET_PROTOCOL_MIN))
                goto nla_put_failure;
        nlmsg_end(skb2, nlh2);

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

nla_put_failure:
        nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
        kfree_skb(skb2);
        return -EMSGSIZE;
}

/* Get set by name or index, from userspace */

static int ip_set_byname(struct sk_buff *skb, const struct nfnl_info *info,
                         const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct sk_buff *skb2;
        struct nlmsghdr *nlh2;
        ip_set_id_t id = IPSET_INVALID_ID;
        const struct ip_set *set;

        if (unlikely(protocol_failed(attr) ||

                     !attr[IPSET_ATTR_SETNAME]))
                return -IPSET_ERR_PROTOCOL;

        set = find_set_and_id(inst, nla_data(attr[IPSET_ATTR_SETNAME]), &id);
        if (id == IPSET_INVALID_ID)
                return -ENOENT;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb2)
                return -ENOMEM;

        nlh2 = start_msg(skb2, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, 0,
                         IPSET_CMD_GET_BYNAME);
        if (!nlh2)
                goto nlmsg_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, protocol(attr)) ||
            nla_put_u8(skb2, IPSET_ATTR_FAMILY, set->family) ||
            nla_put_net16(skb2, IPSET_ATTR_INDEX, htons(id)))
                goto nla_put_failure;
        nlmsg_end(skb2, nlh2);

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

nla_put_failure:
        nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
        kfree_skb(skb2);
        return -EMSGSIZE;
}

static const struct nla_policy ip_set_index_policy[IPSET_ATTR_CMD_MAX + 1] = {
        [IPSET_ATTR_PROTOCOL]   = { .type = NLA_U8 },
        [IPSET_ATTR_INDEX]      = { .type = NLA_U16 },
};

static int ip_set_byindex(struct sk_buff *skb, const struct nfnl_info *info,
                          const struct nlattr * const attr[])
{
        struct ip_set_net *inst = ip_set_pernet(info->net);
        struct sk_buff *skb2;
        struct nlmsghdr *nlh2;
        ip_set_id_t id = IPSET_INVALID_ID;
        const struct ip_set *set;

        if (unlikely(protocol_failed(attr) ||
                     !attr[IPSET_ATTR_INDEX]))
                return -IPSET_ERR_PROTOCOL;

        id = ip_set_get_h16(attr[IPSET_ATTR_INDEX]);
        if (id >= inst->ip_set_max)
                return -ENOENT;
        set = ip_set(inst, id);
        if (set == NULL)
                return -ENOENT;

        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb2)
                return -ENOMEM;

        nlh2 = start_msg(skb2, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, 0,
                         IPSET_CMD_GET_BYINDEX);
        if (!nlh2)
                goto nlmsg_failure;
        if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, protocol(attr)) ||
            nla_put_string(skb2, IPSET_ATTR_SETNAME, set->name))
                goto nla_put_failure;
        nlmsg_end(skb2, nlh2);

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

nla_put_failure:
        nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
        kfree_skb(skb2);
        return -EMSGSIZE;
}

static const struct nfnl_callback ip_set_netlink_subsys_cb[IPSET_MSG_MAX] = {
        [IPSET_CMD_NONE]        = {
                .call           = ip_set_none,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
        },
        [IPSET_CMD_CREATE]      = {
                .call           = ip_set_create,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_create_policy,
        },
        [IPSET_CMD_DESTROY]     = {
                .call           = ip_set_destroy,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname_policy,
        },
        [IPSET_CMD_FLUSH]       = {
                .call           = ip_set_flush,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname_policy,
        },
        [IPSET_CMD_RENAME]      = {
                .call           = ip_set_rename,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname2_policy,
        },
        [IPSET_CMD_SWAP]        = {
                .call           = ip_set_swap,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname2_policy,
        },
        [IPSET_CMD_LIST]        = {
                .call           = ip_set_dump,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_dump_policy,
        },
        [IPSET_CMD_SAVE]        = {
                .call           = ip_set_dump,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname_policy,
        },
        [IPSET_CMD_ADD] = {
                .call           = ip_set_uadd,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_adt_policy,
        },
        [IPSET_CMD_DEL] = {
                .call           = ip_set_udel,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_adt_policy,
        },
        [IPSET_CMD_TEST]        = {
                .call           = ip_set_utest,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_adt_policy,
        },
        [IPSET_CMD_HEADER]      = {
                .call           = ip_set_header,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname_policy,
        },
        [IPSET_CMD_TYPE]        = {
                .call           = ip_set_type,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_type_policy,
        },
        [IPSET_CMD_PROTOCOL]    = {
                .call           = ip_set_protocol,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_protocol_policy,
        },
        [IPSET_CMD_GET_BYNAME]  = {
                .call           = ip_set_byname,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_setname_policy,
        },
        [IPSET_CMD_GET_BYINDEX] = {
                .call           = ip_set_byindex,
                .type           = NFNL_CB_MUTEX,
                .attr_count     = IPSET_ATTR_CMD_MAX,
                .policy         = ip_set_index_policy,
        },
};

static struct nfnetlink_subsystem ip_set_netlink_subsys __read_mostly = {
        .name           = "ip_set",
        .subsys_id      = NFNL_SUBSYS_IPSET,
        .cb_count       = IPSET_MSG_MAX,
        .cb             = ip_set_netlink_subsys_cb,
};

/* Interface to iptables/ip6tables */

static int
ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
{
        unsigned int *op;
        void *data;
        int copylen = *len, ret = 0;
        struct net *net = sock_net(sk);
        struct ip_set_net *inst = ip_set_pernet(net);

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;
        if (optval != SO_IP_SET)
                return -EBADF;
        if (*len < sizeof(unsigned int))
                return -EINVAL;

        data = vmalloc(*len);
        if (!data)
                return -ENOMEM;
        if (copy_from_user(data, user, *len) != 0) {
                ret = -EFAULT;
                goto done;
        }
        op = data;

        if (*op < IP_SET_OP_VERSION) {
                /* Check the version at the beginning of operations */
                struct ip_set_req_version *req_version = data;

                if (*len < sizeof(struct ip_set_req_version)) {
                        ret = -EINVAL;
                        goto done;
                }

                if (req_version->version < IPSET_PROTOCOL_MIN) {
                        ret = -EPROTO;
                        goto done;
                }
        }

        switch (*op) {
        case IP_SET_OP_VERSION: {
                struct ip_set_req_version *req_version = data;

                if (*len != sizeof(struct ip_set_req_version)) {
                        ret = -EINVAL;
                        goto done;
                }

                req_version->version = IPSET_PROTOCOL;
                if (copy_to_user(user, req_version,
                                 sizeof(struct ip_set_req_version)))
                        ret = -EFAULT;
                goto done;
        }
        case IP_SET_OP_GET_BYNAME: {
                struct ip_set_req_get_set *req_get = data;
                ip_set_id_t id;

                if (*len != sizeof(struct ip_set_req_get_set)) {
                        ret = -EINVAL;
                        goto done;
                }
                req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
                nfnl_lock(NFNL_SUBSYS_IPSET);
                find_set_and_id(inst, req_get->set.name, &id);
                req_get->set.index = id;
                nfnl_unlock(NFNL_SUBSYS_IPSET);
                goto copy;
        }
        case IP_SET_OP_GET_FNAME: {
                struct ip_set_req_get_set_family *req_get = data;
                ip_set_id_t id;

                if (*len != sizeof(struct ip_set_req_get_set_family)) {
                        ret = -EINVAL;
                        goto done;
                }
                req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
                nfnl_lock(NFNL_SUBSYS_IPSET);
                find_set_and_id(inst, req_get->set.name, &id);
                req_get->set.index = id;
                if (id != IPSET_INVALID_ID)
                        req_get->family = ip_set(inst, id)->family;
                nfnl_unlock(NFNL_SUBSYS_IPSET);
                goto copy;
        }
        case IP_SET_OP_GET_BYINDEX: {
                struct ip_set_req_get_set *req_get = data;
                struct ip_set *set;

                if (*len != sizeof(struct ip_set_req_get_set) ||
                    req_get->set.index >= inst->ip_set_max) {
                        ret = -EINVAL;
                        goto done;
                }
                nfnl_lock(NFNL_SUBSYS_IPSET);
                set = ip_set(inst, req_get->set.index);
                ret = strscpy(req_get->set.name, set ? set->name : "",
                              IPSET_MAXNAMELEN);
                nfnl_unlock(NFNL_SUBSYS_IPSET);
                if (ret < 0)
                        goto done;
                goto copy;
        }
        default:
                ret = -EBADMSG;
                goto done;
        }       /* end of switch(op) */

copy:
        if (copy_to_user(user, data, copylen))
                ret = -EFAULT;

done:
        vfree(data);
        if (ret > 0)
                ret = 0;
        return ret;
}

static struct nf_sockopt_ops so_set __read_mostly = {
        .pf             = PF_INET,
        .get_optmin     = SO_IP_SET,
        .get_optmax     = SO_IP_SET + 1,
        .get            = ip_set_sockfn_get,
        .owner          = THIS_MODULE,
};

static int __net_init
ip_set_net_init(struct net *net)
{
        struct ip_set_net *inst = ip_set_pernet(net);
        struct ip_set **list;

        inst->ip_set_max = max_sets ? max_sets : CONFIG_IP_SET_MAX;
        if (inst->ip_set_max >= IPSET_INVALID_ID)
                inst->ip_set_max = IPSET_INVALID_ID - 1;

        list = kvcalloc(inst->ip_set_max, sizeof(struct ip_set *), GFP_KERNEL);
        if (!list)
                return -ENOMEM;
        inst->is_deleted = false;
        inst->is_destroyed = false;
        rcu_assign_pointer(inst->ip_set_list, list);
        return 0;
}

static void __net_exit
ip_set_net_exit(struct net *net)
{
        struct ip_set_net *inst = ip_set_pernet(net);

        struct ip_set *set = NULL;
        ip_set_id_t i;

        inst->is_deleted = true; /* flag for ip_set_nfnl_put */

        nfnl_lock(NFNL_SUBSYS_IPSET);
        for (i = 0; i < inst->ip_set_max; i++) {
                set = ip_set(inst, i);
                if (set) {
                        ip_set(inst, i) = NULL;
                        ip_set_destroy_set(set);
                }
        }
        nfnl_unlock(NFNL_SUBSYS_IPSET);
        kvfree(rcu_dereference_protected(inst->ip_set_list, 1));
}

static struct pernet_operations ip_set_net_ops = {
        .init   = ip_set_net_init,
        .exit   = ip_set_net_exit,
        .id     = &ip_set_net_id,
        .size   = sizeof(struct ip_set_net),
};

static int __init
ip_set_init(void)
{
        int ret = register_pernet_subsys(&ip_set_net_ops);

        if (ret) {
                pr_err("ip_set: cannot register pernet_subsys.\n");
                return ret;
        }

        ret = nfnetlink_subsys_register(&ip_set_netlink_subsys);
        if (ret != 0) {
                pr_err("ip_set: cannot register with nfnetlink.\n");
                unregister_pernet_subsys(&ip_set_net_ops);
                return ret;
        }

        ret = nf_register_sockopt(&so_set);
        if (ret != 0) {
                pr_err("SO_SET registry failed: %d\n", ret);
                nfnetlink_subsys_unregister(&ip_set_netlink_subsys);
                unregister_pernet_subsys(&ip_set_net_ops);
                return ret;
        }

        return 0;
}

static void __exit
ip_set_fini(void)
{
        nf_unregister_sockopt(&so_set);
        nfnetlink_subsys_unregister(&ip_set_netlink_subsys);

        unregister_pernet_subsys(&ip_set_net_ops);
        pr_debug("these are the famous last words\n");
}

module_init(ip_set_init);
module_exit(ip_set_fini);

MODULE_DESCRIPTION("ip_set: protocol " __stringify(IPSET_PROTOCOL));