// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2008-2013 Jozsef Kadlecsik <kadlec@netfilter.org> */

/* Kernel module implementing an IP set type: the list:set type */

#include <linux/module.h>
#include <linux/ip.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/errno.h>

#include <linux/netfilter/ipset/ip_set.h>
#include <linux/netfilter/ipset/ip_set_list.h>

#define IPSET_TYPE_REV_MIN      0
/*                              1    Counters support added */
/*                              2    Comments support added */
#define IPSET_TYPE_REV_MAX      3 /* skbinfo support added */

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jozsef Kadlecsik <kadlec@netfilter.org>");
IP_SET_MODULE_DESC("list:set", IPSET_TYPE_REV_MIN, IPSET_TYPE_REV_MAX);
MODULE_ALIAS("ip_set_list:set");

/* Member elements  */
struct set_elem {
        struct rcu_head rcu;
        struct list_head list;
        struct ip_set *set;     /* Sigh, in order to cleanup reference */
        ip_set_id_t id;
} __aligned(__alignof__(u64));

struct set_adt_elem {
        ip_set_id_t id;
        ip_set_id_t refid;
        int before;
};

/* Type structure */
struct list_set {
        u32 size;               /* size of set list array */
        struct timer_list gc;   /* garbage collection */
        struct ip_set *set;     /* attached to this ip_set */
        struct net *net;        /* namespace */
        struct list_head members; /* the set members */
};

static int
list_set_ktest(struct ip_set *set, const struct sk_buff *skb,
               const struct xt_action_param *par,
               struct ip_set_adt_opt *opt, const struct ip_set_ext *ext)
{
        struct list_set *map = set->data;
        struct ip_set_ext *mext = &opt->ext;
        struct set_elem *e;
        u32 flags = opt->cmdflags;
        int ret;

        /* Don't lookup sub-counters at all */
        opt->cmdflags &= ~IPSET_FLAG_MATCH_COUNTERS;
        if (opt->cmdflags & IPSET_FLAG_SKIP_SUBCOUNTER_UPDATE)
                opt->cmdflags |= IPSET_FLAG_SKIP_COUNTER_UPDATE;
        list_for_each_entry_rcu(e, &map->members, list) {
                ret = ip_set_test(e->id, skb, par, opt);
                if (ret <= 0)
                        continue;
                if (ip_set_match_extensions(set, ext, mext, flags, e))
                        return 1;
        }
        return 0;
}

static int
list_set_kadd(struct ip_set *set, const struct sk_buff *skb,
              const struct xt_action_param *par,
              struct ip_set_adt_opt *opt, const struct ip_set_ext *ext)
{
        struct list_set *map = set->data;
        struct set_elem *e;
        int ret;

        list_for_each_entry_rcu(e, &map->members, list) {
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(e, set)))
                        continue;
                ret = ip_set_add(e->id, skb, par, opt);
                if (ret == 0)
                        return ret;
        }
        return 0;
}

static int
list_set_kdel(struct ip_set *set, const struct sk_buff *skb,
              const struct xt_action_param *par,
              struct ip_set_adt_opt *opt, const struct ip_set_ext *ext)
{
        struct list_set *map = set->data;
        struct set_elem *e;
        int ret;

        list_for_each_entry_rcu(e, &map->members, list) {
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(e, set)))
                        continue;
                ret = ip_set_del(e->id, skb, par, opt);
                if (ret == 0)
                        return ret;
        }
        return 0;
}

static int
list_set_kadt(struct ip_set *set, const struct sk_buff *skb,
              const struct xt_action_param *par,
              enum ipset_adt adt, struct ip_set_adt_opt *opt)
{
        struct ip_set_ext ext = IP_SET_INIT_KEXT(skb, opt, set);
        int ret = -EINVAL;

        rcu_read_lock();
        switch (adt) {
        case IPSET_TEST:
                ret = list_set_ktest(set, skb, par, opt, &ext);
                break;
        case IPSET_ADD:
                ret = list_set_kadd(set, skb, par, opt, &ext);
                break;
        case IPSET_DEL:
                ret = list_set_kdel(set, skb, par, opt, &ext);
                break;
        default:
                break;
        }
        rcu_read_unlock();

        return ret;
}

/* Userspace interfaces: we are protected by the nfnl mutex */

static void
__list_set_del_rcu(struct rcu_head * rcu)
{
        struct set_elem *e = container_of(rcu, struct set_elem, rcu);
        struct ip_set *set = e->set;

        ip_set_ext_destroy(set, e);
        kfree(e);
}

static void
list_set_del(struct ip_set *set, struct set_elem *e)
{
        struct list_set *map = set->data;

        set->elements--;
        list_del_rcu(&e->list);
        ip_set_put_byindex(map->net, e->id);
        call_rcu(&e->rcu, __list_set_del_rcu);
}

static void
list_set_replace(struct ip_set *set, struct set_elem *e, struct set_elem *old)
{
        struct list_set *map = set->data;

        list_replace_rcu(&old->list, &e->list);
        ip_set_put_byindex(map->net, old->id);
        call_rcu(&old->rcu, __list_set_del_rcu);
}

static void
set_cleanup_entries(struct ip_set *set)
{
        struct list_set *map = set->data;
        struct set_elem *e, *n;

        list_for_each_entry_safe(e, n, &map->members, list)
                if (ip_set_timeout_expired(ext_timeout(e, set)))
                        list_set_del(set, e);
}

static int
list_set_utest(struct ip_set *set, void *value, const struct ip_set_ext *ext,
               struct ip_set_ext *mext, u32 flags)
{
        struct list_set *map = set->data;
        struct set_adt_elem *d = value;
        struct set_elem *e, *next, *prev = NULL;
        int ret = 0;

        rcu_read_lock();
        list_for_each_entry_rcu(e, &map->members, list) {
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(e, set)))
                        continue;
                else if (e->id != d->id) {
                        prev = e;
                        continue;
                }

                if (d->before == 0) {
                        ret = 1;
                        goto out;
                } else if (d->before > 0) {
                        next = list_next_entry(e, list);
                        ret = !list_is_last(&e->list, &map->members) &&
                              next->id == d->refid;
                } else {
                        ret = prev && prev->id == d->refid;
                }
                goto out;
        }
out:
        rcu_read_unlock();
        return ret;
}

static void
list_set_init_extensions(struct ip_set *set, const struct ip_set_ext *ext,
                         struct set_elem *e)
{
        if (SET_WITH_COUNTER(set))
                ip_set_init_counter(ext_counter(e, set), ext);
        if (SET_WITH_COMMENT(set))
                ip_set_init_comment(set, ext_comment(e, set), ext);
        if (SET_WITH_SKBINFO(set))
                ip_set_init_skbinfo(ext_skbinfo(e, set), ext);
        /* Update timeout last */
        if (SET_WITH_TIMEOUT(set))
                ip_set_timeout_set(ext_timeout(e, set), ext->timeout);
}

static int
list_set_uadd(struct ip_set *set, void *value, const struct ip_set_ext *ext,
              struct ip_set_ext *mext, u32 flags)
{
        struct list_set *map = set->data;
        struct set_adt_elem *d = value;
        struct set_elem *e, *n, *prev, *next;
        bool flag_exist = flags & IPSET_FLAG_EXIST;

        /* Find where to add the new entry */
        n = prev = next = NULL;
        list_for_each_entry_rcu(e, &map->members, list) {
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(e, set)))
                        continue;
                else if (d->id == e->id)
                        n = e;
                else if (d->before == 0 || e->id != d->refid)
                        continue;
                else if (d->before > 0)
                        next = e;
                else
                        prev = e;
        }

        /* If before/after is used on an empty set */
        if ((d->before > 0 && !next) ||
            (d->before < 0 && !prev))
                return -IPSET_ERR_REF_EXIST;

        /* Re-add already existing element */
        if (n) {
                if (!flag_exist)
                        return -IPSET_ERR_EXIST;
                /* Update extensions */
                ip_set_ext_destroy(set, n);
                list_set_init_extensions(set, ext, n);

                /* Set is already added to the list */
                ip_set_put_byindex(map->net, d->id);
                return 0;
        }
        /* Add new entry */
        if (d->before == 0) {
                /* Append  */
                n = list_empty(&map->members) ? NULL :
                    list_last_entry(&map->members, struct set_elem, list);
        } else if (d->before > 0) {
                /* Insert after next element */
                if (!list_is_last(&next->list, &map->members))
                        n = list_next_entry(next, list);
        } else {
                /* Insert before prev element */
                if (prev->list.prev != &map->members)
                        n = list_prev_entry(prev, list);
        }
        /* Can we replace a timed out entry? */
        if (n &&
            !(SET_WITH_TIMEOUT(set) &&
              ip_set_timeout_expired(ext_timeout(n, set))))
                n = NULL;

        e = kzalloc(set->dsize, GFP_ATOMIC);
        if (!e)
                return -ENOMEM;
        e->id = d->id;
        e->set = set;
        INIT_LIST_HEAD(&e->list);
        list_set_init_extensions(set, ext, e);
        if (n)
                list_set_replace(set, e, n);
        else if (next)
                list_add_tail_rcu(&e->list, &next->list);
        else if (prev)
                list_add_rcu(&e->list, &prev->list);
        else
                list_add_tail_rcu(&e->list, &map->members);
        set->elements++;

        return 0;
}

static int
list_set_udel(struct ip_set *set, void *value, const struct ip_set_ext *ext,
              struct ip_set_ext *mext, u32 flags)
{
        struct list_set *map = set->data;
        struct set_adt_elem *d = value;
        struct set_elem *e, *n, *next, *prev = NULL;

        list_for_each_entry_safe(e, n, &map->members, list) {
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(e, set)))
                        continue;
                else if (e->id != d->id) {
                        prev = e;
                        continue;
                }

                if (d->before > 0) {
                        next = list_next_entry(e, list);
                        if (list_is_last(&e->list, &map->members) ||
                            next->id != d->refid)
                                return -IPSET_ERR_REF_EXIST;
                } else if (d->before < 0) {
                        if (!prev || prev->id != d->refid)
                                return -IPSET_ERR_REF_EXIST;
                }
                list_set_del(set, e);
                return 0;
        }
        return d->before != 0 ? -IPSET_ERR_REF_EXIST : -IPSET_ERR_EXIST;
}

static int
list_set_uadt(struct ip_set *set, struct nlattr *tb[],
              enum ipset_adt adt, u32 *lineno, u32 flags, bool retried)
{
        struct list_set *map = set->data;
        ipset_adtfn adtfn = set->variant->adt[adt];
        struct set_adt_elem e = { .refid = IPSET_INVALID_ID };
        struct ip_set_ext ext = IP_SET_INIT_UEXT(set);
        struct ip_set *s;
        int ret = 0;

        if (tb[IPSET_ATTR_LINENO])
                *lineno = nla_get_u32(tb[IPSET_ATTR_LINENO]);

        if (unlikely(!tb[IPSET_ATTR_NAME] ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_CADT_FLAGS)))
                return -IPSET_ERR_PROTOCOL;

        ret = ip_set_get_extensions(set, tb, &ext);
        if (ret)
                return ret;
        e.id = ip_set_get_byname(map->net, tb[IPSET_ATTR_NAME], &s);
        if (e.id == IPSET_INVALID_ID)
                return -IPSET_ERR_NAME;
        /* "Loop detection" */
        if (s->type->features & IPSET_TYPE_NAME) {
                ret = -IPSET_ERR_LOOP;
                goto finish;
        }

        if (tb[IPSET_ATTR_CADT_FLAGS]) {
                u32 f = ip_set_get_h32(tb[IPSET_ATTR_CADT_FLAGS]);

                e.before = f & IPSET_FLAG_BEFORE;
        }

        if (e.before && !tb[IPSET_ATTR_NAMEREF]) {
                ret = -IPSET_ERR_BEFORE;
                goto finish;
        }

        if (tb[IPSET_ATTR_NAMEREF]) {
                e.refid = ip_set_get_byname(map->net,
                                            tb[IPSET_ATTR_NAMEREF],
                                            &s);
                if (e.refid == IPSET_INVALID_ID) {
                        ret = -IPSET_ERR_NAMEREF;
                        goto finish;
                }
                if (!e.before)
                        e.before = -1;
        }
        if (adt != IPSET_TEST && SET_WITH_TIMEOUT(set))
                set_cleanup_entries(set);

        ret = adtfn(set, &e, &ext, &ext, flags);

finish:
        if (e.refid != IPSET_INVALID_ID)
                ip_set_put_byindex(map->net, e.refid);
        if (adt != IPSET_ADD || ret)
                ip_set_put_byindex(map->net, e.id);

        return ip_set_eexist(ret, flags) ? 0 : ret;
}

static void
list_set_flush(struct ip_set *set)
{
        struct list_set *map = set->data;
        struct set_elem *e, *n;

        list_for_each_entry_safe(e, n, &map->members, list)
                list_set_del(set, e);
        set->elements = 0;
        set->ext_size = 0;
}

static void
list_set_destroy(struct ip_set *set)
{
        struct list_set *map = set->data;

        WARN_ON_ONCE(!list_empty(&map->members));
        kfree(map);

        set->data = NULL;
}

/* Calculate the actual memory size of the set data */
static size_t
list_set_memsize(const struct list_set *map, size_t dsize)
{
        struct set_elem *e;
        u32 n = 0;

        rcu_read_lock();
        list_for_each_entry_rcu(e, &map->members, list)
                n++;
        rcu_read_unlock();

        return (sizeof(*map) + n * dsize);
}

static int
list_set_head(struct ip_set *set, struct sk_buff *skb)
{
        const struct list_set *map = set->data;
        struct nlattr *nested;
        size_t memsize = list_set_memsize(map, set->dsize) + set->ext_size;

        nested = nla_nest_start(skb, IPSET_ATTR_DATA);
        if (!nested)
                goto nla_put_failure;
        if (nla_put_net32(skb, IPSET_ATTR_SIZE, htonl(map->size)) ||
            nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) ||
            nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize)) ||
            nla_put_net32(skb, IPSET_ATTR_ELEMENTS, htonl(set->elements)))
                goto nla_put_failure;
        if (unlikely(ip_set_put_flags(skb, set)))
                goto nla_put_failure;
        nla_nest_end(skb, nested);

        return 0;
nla_put_failure:
        return -EMSGSIZE;
}

static int
list_set_list(const struct ip_set *set,
              struct sk_buff *skb, struct netlink_callback *cb)
{
        const struct list_set *map = set->data;
        struct nlattr *atd, *nested;
        u32 i = 0, first = cb->args[IPSET_CB_ARG0];
        char name[IPSET_MAXNAMELEN];
        struct set_elem *e;
        int ret = 0;

        atd = nla_nest_start(skb, IPSET_ATTR_ADT);
        if (!atd)
                return -EMSGSIZE;

        rcu_read_lock();
        list_for_each_entry_rcu(e, &map->members, list) {
                if (i < first ||
                    (SET_WITH_TIMEOUT(set) &&
                     ip_set_timeout_expired(ext_timeout(e, set)))) {
                        i++;
                        continue;
                }
                nested = nla_nest_start(skb, IPSET_ATTR_DATA);
                if (!nested)
                        goto nla_put_failure;
                ip_set_name_byindex(map->net, e->id, name);
                if (nla_put_string(skb, IPSET_ATTR_NAME, name))
                        goto nla_put_failure;
                if (ip_set_put_extensions(skb, set, e, true))
                        goto nla_put_failure;
                nla_nest_end(skb, nested);
                i++;
        }

        nla_nest_end(skb, atd);
        /* Set listing finished */
        cb->args[IPSET_CB_ARG0] = 0;
        goto out;

nla_put_failure:
        nla_nest_cancel(skb, nested);
        if (unlikely(i == first)) {
                nla_nest_cancel(skb, atd);
                cb->args[IPSET_CB_ARG0] = 0;
                ret = -EMSGSIZE;
        } else {
                cb->args[IPSET_CB_ARG0] = i;
                nla_nest_end(skb, atd);
        }
out:
        rcu_read_unlock();
        return ret;
}

static bool
list_set_same_set(const struct ip_set *a, const struct ip_set *b)
{
        const struct list_set *x = a->data;
        const struct list_set *y = b->data;

        return x->size == y->size &&
               a->timeout == b->timeout &&
               a->extensions == b->extensions;
}

static void
list_set_cancel_gc(struct ip_set *set)
{
        struct list_set *map = set->data;

        if (SET_WITH_TIMEOUT(set))
                timer_shutdown_sync(&map->gc);

        /* Flush list to drop references to other ipsets */
        list_set_flush(set);
}

static const struct ip_set_type_variant set_variant = {
        .kadt   = list_set_kadt,
        .uadt   = list_set_uadt,
        .adt    = {
                [IPSET_ADD] = list_set_uadd,
                [IPSET_DEL] = list_set_udel,
                [IPSET_TEST] = list_set_utest,
        },
        .destroy = list_set_destroy,
        .flush  = list_set_flush,
        .head   = list_set_head,
        .list   = list_set_list,
        .same_set = list_set_same_set,
        .cancel_gc = list_set_cancel_gc,
};

static void
list_set_gc(struct timer_list *t)
{
        struct list_set *map = timer_container_of(map, t, gc);
        struct ip_set *set = map->set;

        spin_lock_bh(&set->lock);
        set_cleanup_entries(set);
        spin_unlock_bh(&set->lock);

        map->gc.expires = jiffies + IPSET_GC_PERIOD(set->timeout) * HZ;
        add_timer(&map->gc);
}

static void
list_set_gc_init(struct ip_set *set, void (*gc)(struct timer_list *t))
{
        struct list_set *map = set->data;

        timer_setup(&map->gc, gc, 0);
        mod_timer(&map->gc, jiffies + IPSET_GC_PERIOD(set->timeout) * HZ);
}

/* Create list:set type of sets */

static bool
init_list_set(struct net *net, struct ip_set *set, u32 size)
{
        struct list_set *map;

        map = kzalloc_obj(*map);
        if (!map)
                return false;

        map->size = size;
        map->net = net;
        map->set = set;
        INIT_LIST_HEAD(&map->members);
        set->data = map;

        return true;
}

static struct lock_class_key list_set_lockdep_key;

static int
list_set_create(struct net *net, struct ip_set *set, struct nlattr *tb[],
                u32 flags)
{
        u32 size = IP_SET_LIST_DEFAULT_SIZE;

        if (unlikely(!ip_set_optattr_netorder(tb, IPSET_ATTR_SIZE) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_TIMEOUT) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_CADT_FLAGS)))
                return -IPSET_ERR_PROTOCOL;

        if (tb[IPSET_ATTR_SIZE])
                size = ip_set_get_h32(tb[IPSET_ATTR_SIZE]);
        if (size < IP_SET_LIST_MIN_SIZE)
                size = IP_SET_LIST_MIN_SIZE;

        lockdep_set_class(&set->lock, &list_set_lockdep_key);
        set->variant = &set_variant;
        set->dsize = ip_set_elem_len(set, tb, sizeof(struct set_elem),
                                     __alignof__(struct set_elem));
        if (!init_list_set(net, set, size))
                return -ENOMEM;
        if (tb[IPSET_ATTR_TIMEOUT]) {
                set->timeout = ip_set_timeout_uget(tb[IPSET_ATTR_TIMEOUT]);
                list_set_gc_init(set, list_set_gc);
        }
        return 0;
}

static struct ip_set_type list_set_type __read_mostly = {
        .name           = "list:set",
        .protocol       = IPSET_PROTOCOL,
        .features       = IPSET_TYPE_NAME | IPSET_DUMP_LAST,
        .dimension      = IPSET_DIM_ONE,
        .family         = NFPROTO_UNSPEC,
        .revision_min   = IPSET_TYPE_REV_MIN,
        .revision_max   = IPSET_TYPE_REV_MAX,
        .create         = list_set_create,
        .create_policy  = {
                [IPSET_ATTR_SIZE]       = { .type = NLA_U32 },
                [IPSET_ATTR_TIMEOUT]    = { .type = NLA_U32 },
                [IPSET_ATTR_CADT_FLAGS] = { .type = NLA_U32 },
        },
        .adt_policy     = {
                [IPSET_ATTR_NAME]       = { .type = NLA_STRING,
                                            .len = IPSET_MAXNAMELEN },
                [IPSET_ATTR_NAMEREF]    = { .type = NLA_STRING,
                                            .len = IPSET_MAXNAMELEN },
                [IPSET_ATTR_TIMEOUT]    = { .type = NLA_U32 },
                [IPSET_ATTR_LINENO]     = { .type = NLA_U32 },
                [IPSET_ATTR_CADT_FLAGS] = { .type = NLA_U32 },
                [IPSET_ATTR_BYTES]      = { .type = NLA_U64 },
                [IPSET_ATTR_PACKETS]    = { .type = NLA_U64 },
                [IPSET_ATTR_COMMENT]    = { .type = NLA_NUL_STRING,
                                            .len  = IPSET_MAX_COMMENT_SIZE },
                [IPSET_ATTR_SKBMARK]    = { .type = NLA_U64 },
                [IPSET_ATTR_SKBPRIO]    = { .type = NLA_U32 },
                [IPSET_ATTR_SKBQUEUE]   = { .type = NLA_U16 },
        },
        .me             = THIS_MODULE,
};

static int __init
list_set_init(void)
{
        return ip_set_type_register(&list_set_type);
}

static void __exit
list_set_fini(void)
{
        rcu_barrier();
        ip_set_type_unregister(&list_set_type);
}

module_init(list_set_init);
module_exit(list_set_fini);