/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/module.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tproxy.h>
#include <net/inet_sock.h>
#include <net/tcp.h>
#include <linux/if_ether.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#endif
struct nft_tproxy {
u8 sreg_addr;
u8 sreg_port;
u8 family;
};
static void nft_tproxy_eval_v4(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_tproxy *priv = nft_expr_priv(expr);
struct sk_buff *skb = pkt->skb;
const struct iphdr *iph = ip_hdr(skb);
struct udphdr _hdr, *hp;
__be32 taddr = 0;
__be16 tport = 0;
struct sock *sk;
if (pkt->tprot != IPPROTO_TCP &&
pkt->tprot != IPPROTO_UDP) {
regs->verdict.code = NFT_BREAK;
return;
}
hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr);
if (!hp) {
regs->verdict.code = NFT_BREAK;
return;
}
/* check if there's an ongoing connection on the packet addresses, this
* happens if the redirect already happened and the current packet
* belongs to an already established connection
*/
sk = nf_tproxy_get_sock_v4(nft_net(pkt), skb, iph->protocol,
iph->saddr, iph->daddr,
hp->source, hp->dest,
skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED);
if (priv->sreg_addr)
taddr = nft_reg_load_be32(®s->data[priv->sreg_addr]);
taddr = nf_tproxy_laddr4(skb, taddr, iph->daddr);
if (priv->sreg_port)
tport = nft_reg_load_be16(®s->data[priv->sreg_port]);
if (!tport)
tport = hp->dest;
/* UDP has no TCP_TIME_WAIT state, so we never enter here */
if (sk && sk->sk_state == TCP_TIME_WAIT) {
/* reopening a TIME_WAIT connection needs special handling */
sk = nf_tproxy_handle_time_wait4(nft_net(pkt), skb, taddr, tport, sk);
} else if (!sk) {
/* no, there's no established connection, check if
* there's a listener on the redirected addr/port
*/
sk = nf_tproxy_get_sock_v4(nft_net(pkt), skb, iph->protocol,
iph->saddr, taddr,
hp->source, tport,
skb->dev, NF_TPROXY_LOOKUP_LISTENER);
}
if (sk && nf_tproxy_sk_is_transparent(sk))
nf_tproxy_assign_sock(skb, sk);
else
regs->verdict.code = NFT_BREAK;
}
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
static void nft_tproxy_eval_v6(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_tproxy *priv = nft_expr_priv(expr);
struct sk_buff *skb = pkt->skb;
const struct ipv6hdr *iph = ipv6_hdr(skb);
int thoff = nft_thoff(pkt);
struct udphdr _hdr, *hp;
struct in6_addr taddr;
__be16 tport = 0;
struct sock *sk;
int l4proto;
memset(&taddr, 0, sizeof(taddr));
if (pkt->tprot != IPPROTO_TCP &&
pkt->tprot != IPPROTO_UDP) {
regs->verdict.code = NFT_BREAK;
return;
}
l4proto = pkt->tprot;
hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
if (hp == NULL) {
regs->verdict.code = NFT_BREAK;
return;
}
/* check if there's an ongoing connection on the packet addresses, this
* happens if the redirect already happened and the current packet
* belongs to an already established connection
*/
sk = nf_tproxy_get_sock_v6(nft_net(pkt), skb, thoff, l4proto,
&iph->saddr, &iph->daddr,
hp->source, hp->dest,
nft_in(pkt), NF_TPROXY_LOOKUP_ESTABLISHED);
if (priv->sreg_addr)
memcpy(&taddr, ®s->data[priv->sreg_addr], sizeof(taddr));
taddr = *nf_tproxy_laddr6(skb, &taddr, &iph->daddr);
if (priv->sreg_port)
tport = nft_reg_load_be16(®s->data[priv->sreg_port]);
if (!tport)
tport = hp->dest;
/* UDP has no TCP_TIME_WAIT state, so we never enter here */
if (sk && sk->sk_state == TCP_TIME_WAIT) {
/* reopening a TIME_WAIT connection needs special handling */
sk = nf_tproxy_handle_time_wait6(skb, l4proto, thoff,
nft_net(pkt),
&taddr,
tport,
sk);
} else if (!sk) {
/* no there's no established connection, check if
* there's a listener on the redirected addr/port
*/
sk = nf_tproxy_get_sock_v6(nft_net(pkt), skb, thoff,
l4proto, &iph->saddr, &taddr,
hp->source, tport,
nft_in(pkt), NF_TPROXY_LOOKUP_LISTENER);
}
/* NOTE: assign_sock consumes our sk reference */
if (sk && nf_tproxy_sk_is_transparent(sk))
nf_tproxy_assign_sock(skb, sk);
else
regs->verdict.code = NFT_BREAK;
}
#endif
static void nft_tproxy_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_tproxy *priv = nft_expr_priv(expr);
switch (nft_pf(pkt)) {
case NFPROTO_IPV4:
switch (priv->family) {
case NFPROTO_IPV4:
case NFPROTO_UNSPEC:
nft_tproxy_eval_v4(expr, regs, pkt);
return;
}
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
switch (priv->family) {
case NFPROTO_IPV6:
case NFPROTO_UNSPEC:
nft_tproxy_eval_v6(expr, regs, pkt);
return;
}
#endif
}
regs->verdict.code = NFT_BREAK;
}
static const struct nla_policy nft_tproxy_policy[NFTA_TPROXY_MAX + 1] = {
[NFTA_TPROXY_FAMILY] = { .type = NLA_U32 },
[NFTA_TPROXY_REG_ADDR] = { .type = NLA_U32 },
[NFTA_TPROXY_REG_PORT] = { .type = NLA_U32 },
};
static int nft_tproxy_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_tproxy *priv = nft_expr_priv(expr);
unsigned int alen = 0;
int err;
if (!tb[NFTA_TPROXY_FAMILY] ||
(!tb[NFTA_TPROXY_REG_ADDR] && !tb[NFTA_TPROXY_REG_PORT]))
return -EINVAL;
priv->family = ntohl(nla_get_be32(tb[NFTA_TPROXY_FAMILY]));
switch (ctx->family) {
case NFPROTO_IPV4:
if (priv->family != NFPROTO_IPV4)
return -EINVAL;
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
if (priv->family != NFPROTO_IPV6)
return -EINVAL;
break;
#endif
case NFPROTO_INET:
break;
default:
return -EOPNOTSUPP;
}
/* Address is specified but the rule family is not set accordingly */
if (priv->family == NFPROTO_UNSPEC && tb[NFTA_TPROXY_REG_ADDR])
return -EINVAL;
switch (priv->family) {
case NFPROTO_IPV4:
alen = sizeof_field(union nf_inet_addr, in);
err = nf_defrag_ipv4_enable(ctx->net);
if (err)
return err;
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
alen = sizeof_field(union nf_inet_addr, in6);
err = nf_defrag_ipv6_enable(ctx->net);
if (err)
return err;
break;
#endif
case NFPROTO_UNSPEC:
/* No address is specified here */
err = nf_defrag_ipv4_enable(ctx->net);
if (err)
return err;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
err = nf_defrag_ipv6_enable(ctx->net);
if (err)
return err;
#endif
break;
default:
return -EOPNOTSUPP;
}
if (tb[NFTA_TPROXY_REG_ADDR]) {
err = nft_parse_register_load(tb[NFTA_TPROXY_REG_ADDR],
&priv->sreg_addr, alen);
if (err < 0)
return err;
}
if (tb[NFTA_TPROXY_REG_PORT]) {
err = nft_parse_register_load(tb[NFTA_TPROXY_REG_PORT],
&priv->sreg_port, sizeof(u16));
if (err < 0)
return err;
}
return 0;
}
static void nft_tproxy_destroy(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
const struct nft_tproxy *priv = nft_expr_priv(expr);
switch (priv->family) {
case NFPROTO_IPV4:
nf_defrag_ipv4_disable(ctx->net);
break;
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
case NFPROTO_IPV6:
nf_defrag_ipv6_disable(ctx->net);
break;
#endif
case NFPROTO_UNSPEC:
nf_defrag_ipv4_disable(ctx->net);
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
nf_defrag_ipv6_disable(ctx->net);
#endif
break;
}
}
static int nft_tproxy_dump(struct sk_buff *skb,
const struct nft_expr *expr, bool reset)
{
const struct nft_tproxy *priv = nft_expr_priv(expr);
if (nla_put_be32(skb, NFTA_TPROXY_FAMILY, htonl(priv->family)))
return -1;
if (priv->sreg_addr &&
nft_dump_register(skb, NFTA_TPROXY_REG_ADDR, priv->sreg_addr))
return -1;
if (priv->sreg_port &&
nft_dump_register(skb, NFTA_TPROXY_REG_PORT, priv->sreg_port))
return -1;
return 0;
}
static int nft_tproxy_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nft_data **data)
{
return nft_chain_validate_hooks(ctx->chain, 1 << NF_INET_PRE_ROUTING);
}
static struct nft_expr_type nft_tproxy_type;
static const struct nft_expr_ops nft_tproxy_ops = {
.type = &nft_tproxy_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_tproxy)),
.eval = nft_tproxy_eval,
.init = nft_tproxy_init,
.destroy = nft_tproxy_destroy,
.dump = nft_tproxy_dump,
.reduce = NFT_REDUCE_READONLY,
.validate = nft_tproxy_validate,
};
static struct nft_expr_type nft_tproxy_type __read_mostly = {
.name = "tproxy",
.ops = &nft_tproxy_ops,
.policy = nft_tproxy_policy,
.maxattr = NFTA_TPROXY_MAX,
.owner = THIS_MODULE,
};
static int __init nft_tproxy_module_init(void)
{
return nft_register_expr(&nft_tproxy_type);
}
static void __exit nft_tproxy_module_exit(void)
{
nft_unregister_expr(&nft_tproxy_type);
}
module_init(nft_tproxy_module_init);
module_exit(nft_tproxy_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Máté Eckl");
MODULE_DESCRIPTION("nf_tables tproxy support module");
MODULE_ALIAS_NFT_EXPR("tproxy");
