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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_count.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_zones.h>
struct nft_connlimit {
struct nf_conncount_list list;
u32 limit;
bool invert;
};
static inline void nft_connlimit_do_eval(struct nft_connlimit *priv,
struct nft_regs *regs,
const struct nft_pktinfo *pkt,
const struct nft_set_ext *ext)
{
const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
const struct nf_conntrack_tuple *tuple_ptr;
struct nf_conntrack_tuple tuple;
enum ip_conntrack_info ctinfo;
const struct nf_conn *ct;
unsigned int count;
tuple_ptr = &tuple;
ct = nf_ct_get(pkt->skb, &ctinfo);
if (ct != NULL) {
tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
zone = nf_ct_zone(ct);
} else if (!nf_ct_get_tuplepr(pkt->skb, skb_network_offset(pkt->skb),
nft_pf(pkt), nft_net(pkt), &tuple)) {
regs->verdict.code = NF_DROP;
return;
}
if (nf_conncount_add(nft_net(pkt), &priv->list, tuple_ptr, zone)) {
regs->verdict.code = NF_DROP;
return;
}
count = priv->list.count;
if ((count > priv->limit) ^ priv->invert) {
regs->verdict.code = NFT_BREAK;
return;
}
}
static int nft_connlimit_do_init(const struct nft_ctx *ctx,
const struct nlattr * const tb[],
struct nft_connlimit *priv)
{
bool invert = false;
u32 flags, limit;
if (!tb[NFTA_CONNLIMIT_COUNT])
return -EINVAL;
limit = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_COUNT]));
if (tb[NFTA_CONNLIMIT_FLAGS]) {
flags = ntohl(nla_get_be32(tb[NFTA_CONNLIMIT_FLAGS]));
if (flags & ~NFT_CONNLIMIT_F_INV)
return -EOPNOTSUPP;
if (flags & NFT_CONNLIMIT_F_INV)
invert = true;
}
nf_conncount_list_init(&priv->list);
priv->limit = limit;
priv->invert = invert;
return nf_ct_netns_get(ctx->net, ctx->family);
}
static void nft_connlimit_do_destroy(const struct nft_ctx *ctx,
struct nft_connlimit *priv)
{
nf_ct_netns_put(ctx->net, ctx->family);
nf_conncount_cache_free(&priv->list);
}
static int nft_connlimit_do_dump(struct sk_buff *skb,
struct nft_connlimit *priv)
{
if (nla_put_be32(skb, NFTA_CONNLIMIT_COUNT, htonl(priv->limit)))
goto nla_put_failure;
if (priv->invert &&
nla_put_be32(skb, NFTA_CONNLIMIT_FLAGS, htonl(NFT_CONNLIMIT_F_INV)))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static inline void nft_connlimit_obj_eval(struct nft_object *obj,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_connlimit *priv = nft_obj_data(obj);
nft_connlimit_do_eval(priv, regs, pkt, NULL);
}
static int nft_connlimit_obj_init(const struct nft_ctx *ctx,
const struct nlattr * const tb[],
struct nft_object *obj)
{
struct nft_connlimit *priv = nft_obj_data(obj);
return nft_connlimit_do_init(ctx, tb, priv);
}
static void nft_connlimit_obj_destroy(const struct nft_ctx *ctx,
struct nft_object *obj)
{
struct nft_connlimit *priv = nft_obj_data(obj);
nft_connlimit_do_destroy(ctx, priv);
}
static int nft_connlimit_obj_dump(struct sk_buff *skb,
struct nft_object *obj, bool reset)
{
struct nft_connlimit *priv = nft_obj_data(obj);
return nft_connlimit_do_dump(skb, priv);
}
static const struct nla_policy nft_connlimit_policy[NFTA_CONNLIMIT_MAX + 1] = {
[NFTA_CONNLIMIT_COUNT] = { .type = NLA_U32 },
[NFTA_CONNLIMIT_FLAGS] = { .type = NLA_U32 },
};
static struct nft_object_type nft_connlimit_obj_type;
static const struct nft_object_ops nft_connlimit_obj_ops = {
.type = &nft_connlimit_obj_type,
.size = sizeof(struct nft_connlimit),
.eval = nft_connlimit_obj_eval,
.init = nft_connlimit_obj_init,
.destroy = nft_connlimit_obj_destroy,
.dump = nft_connlimit_obj_dump,
};
static struct nft_object_type nft_connlimit_obj_type __read_mostly = {
.type = NFT_OBJECT_CONNLIMIT,
.ops = &nft_connlimit_obj_ops,
.maxattr = NFTA_CONNLIMIT_MAX,
.policy = nft_connlimit_policy,
.owner = THIS_MODULE,
};
static void nft_connlimit_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_connlimit *priv = nft_expr_priv(expr);
nft_connlimit_do_eval(priv, regs, pkt, NULL);
}
static int nft_connlimit_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
struct nft_connlimit *priv = nft_expr_priv(expr);
return nft_connlimit_do_dump(skb, priv);
}
static int nft_connlimit_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_connlimit *priv = nft_expr_priv(expr);
return nft_connlimit_do_init(ctx, tb, priv);
}
static void nft_connlimit_destroy(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
struct nft_connlimit *priv = nft_expr_priv(expr);
nft_connlimit_do_destroy(ctx, priv);
}
static int nft_connlimit_clone(struct nft_expr *dst, const struct nft_expr *src)
{
struct nft_connlimit *priv_dst = nft_expr_priv(dst);
struct nft_connlimit *priv_src = nft_expr_priv(src);
nf_conncount_list_init(&priv_dst->list);
priv_dst->limit = priv_src->limit;
priv_dst->invert = priv_src->invert;
return 0;
}
static void nft_connlimit_destroy_clone(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
struct nft_connlimit *priv = nft_expr_priv(expr);
nf_conncount_cache_free(&priv->list);
}
static bool nft_connlimit_gc(struct net *net, const struct nft_expr *expr)
{
struct nft_connlimit *priv = nft_expr_priv(expr);
bool ret;
local_bh_disable();
ret = nf_conncount_gc_list(net, &priv->list);
local_bh_enable();
return ret;
}
static struct nft_expr_type nft_connlimit_type;
static const struct nft_expr_ops nft_connlimit_ops = {
.type = &nft_connlimit_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_connlimit)),
.eval = nft_connlimit_eval,
.init = nft_connlimit_init,
.destroy = nft_connlimit_destroy,
.clone = nft_connlimit_clone,
.destroy_clone = nft_connlimit_destroy_clone,
.dump = nft_connlimit_dump,
.gc = nft_connlimit_gc,
};
static struct nft_expr_type nft_connlimit_type __read_mostly = {
.name = "connlimit",
.ops = &nft_connlimit_ops,
.policy = nft_connlimit_policy,
.maxattr = NFTA_CONNLIMIT_MAX,
.flags = NFT_EXPR_STATEFUL | NFT_EXPR_GC,
.owner = THIS_MODULE,
};
static int __init nft_connlimit_module_init(void)
{
int err;
err = nft_register_obj(&nft_connlimit_obj_type);
if (err < 0)
return err;
err = nft_register_expr(&nft_connlimit_type);
if (err < 0)
goto err1;
return 0;
err1:
nft_unregister_obj(&nft_connlimit_obj_type);
return err;
}
static void __exit nft_connlimit_module_exit(void)
{
nft_unregister_expr(&nft_connlimit_type);
nft_unregister_obj(&nft_connlimit_obj_type);
}
module_init(nft_connlimit_module_init);
module_exit(nft_connlimit_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Pablo Neira Ayuso");
MODULE_ALIAS_NFT_EXPR("connlimit");
MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CONNLIMIT);
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