text: // 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(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(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;
  
  	list_for_each_entry(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;
  		} 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;
  		}
  		return ret;
  	}
  	return 0;
  }
  
  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(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, *next, *prev = NULL;
  
  	list_for_each_entry(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) {
  			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, nla_data(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,
  					    nla_data(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;
  	struct set_elem *e, *n;
  
  	if (SET_WITH_TIMEOUT(set))
  		del_timer_sync(&map->gc);
  
  	list_for_each_entry_safe(e, n, &map->members, list) {
  		list_del(&e->list);
  		ip_set_put_byindex(map->net, e->id);
  		ip_set_ext_destroy(set, e);
  		kfree(e);
  	}
  	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 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,
  };
  
  static void
  list_set_gc(struct timer_list *t)
  {
  	struct list_set *map = from_timer(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(sizeof(*map), GFP_KERNEL);
  	if (!map)
  		return false;
  
  	map->size = size;
  	map->net = net;
  	map->set = set;
  	INIT_LIST_HEAD(&map->members);
  	set->data = map;
  
  	return true;
  }
  
  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;
  
  	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);
  