diff options
Diffstat (limited to 'net/netfilter/xt_TPROXY.c')
-rw-r--r-- | net/netfilter/xt_TPROXY.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c new file mode 100644 index 000000000..e4bea1d34 --- /dev/null +++ b/net/netfilter/xt_TPROXY.c @@ -0,0 +1,269 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Transparent proxy support for Linux/iptables + * + * Copyright (c) 2006-2010 BalaBit IT Ltd. + * Author: Balazs Scheidler, Krisztian Kovacs + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/ip.h> +#include <net/checksum.h> +#include <net/udp.h> +#include <net/tcp.h> +#include <net/inet_sock.h> +#include <net/inet_hashtables.h> +#include <linux/inetdevice.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_ipv4/ip_tables.h> + +#include <net/netfilter/ipv4/nf_defrag_ipv4.h> + +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) +#define XT_TPROXY_HAVE_IPV6 1 +#include <net/if_inet6.h> +#include <net/addrconf.h> +#include <net/inet6_hashtables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <net/netfilter/ipv6/nf_defrag_ipv6.h> +#endif + +#include <net/netfilter/nf_tproxy.h> +#include <linux/netfilter/xt_TPROXY.h> + +static unsigned int +tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport, + u_int32_t mark_mask, u_int32_t mark_value) +{ + const struct iphdr *iph = ip_hdr(skb); + struct udphdr _hdr, *hp; + struct sock *sk; + + hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); + if (hp == NULL) + return NF_DROP; + + /* 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(net, skb, iph->protocol, + iph->saddr, iph->daddr, + hp->source, hp->dest, + skb->dev, NF_TPROXY_LOOKUP_ESTABLISHED); + + laddr = nf_tproxy_laddr4(skb, laddr, iph->daddr); + if (!lport) + lport = 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(net, skb, laddr, lport, 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(net, skb, iph->protocol, + iph->saddr, laddr, + hp->source, lport, + skb->dev, NF_TPROXY_LOOKUP_LISTENER); + + /* NOTE: assign_sock consumes our sk reference */ + if (sk && nf_tproxy_sk_is_transparent(sk)) { + /* This should be in a separate target, but we don't do multiple + targets on the same rule yet */ + skb->mark = (skb->mark & ~mark_mask) ^ mark_value; + nf_tproxy_assign_sock(skb, sk); + return NF_ACCEPT; + } + + return NF_DROP; +} + +static unsigned int +tproxy_tg4_v0(struct sk_buff *skb, const struct xt_action_param *par) +{ + const struct xt_tproxy_target_info *tgi = par->targinfo; + + return tproxy_tg4(xt_net(par), skb, tgi->laddr, tgi->lport, + tgi->mark_mask, tgi->mark_value); +} + +static unsigned int +tproxy_tg4_v1(struct sk_buff *skb, const struct xt_action_param *par) +{ + const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; + + return tproxy_tg4(xt_net(par), skb, tgi->laddr.ip, tgi->lport, + tgi->mark_mask, tgi->mark_value); +} + +#ifdef XT_TPROXY_HAVE_IPV6 + +static unsigned int +tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par) +{ + const struct ipv6hdr *iph = ipv6_hdr(skb); + const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; + struct udphdr _hdr, *hp; + struct sock *sk; + const struct in6_addr *laddr; + __be16 lport; + int thoff = 0; + int tproto; + + tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); + if (tproto < 0) + return NF_DROP; + + hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); + if (!hp) + return NF_DROP; + + /* 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(xt_net(par), skb, thoff, tproto, + &iph->saddr, &iph->daddr, + hp->source, hp->dest, + xt_in(par), NF_TPROXY_LOOKUP_ESTABLISHED); + + laddr = nf_tproxy_laddr6(skb, &tgi->laddr.in6, &iph->daddr); + lport = tgi->lport ? tgi->lport : hp->dest; + + /* UDP has no TCP_TIME_WAIT state, so we never enter here */ + if (sk && sk->sk_state == TCP_TIME_WAIT) { + const struct xt_tproxy_target_info_v1 *tgi = par->targinfo; + /* reopening a TIME_WAIT connection needs special handling */ + sk = nf_tproxy_handle_time_wait6(skb, tproto, thoff, + xt_net(par), + &tgi->laddr.in6, + tgi->lport, + 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(xt_net(par), skb, thoff, + tproto, &iph->saddr, laddr, + hp->source, lport, + xt_in(par), NF_TPROXY_LOOKUP_LISTENER); + + /* NOTE: assign_sock consumes our sk reference */ + if (sk && nf_tproxy_sk_is_transparent(sk)) { + /* This should be in a separate target, but we don't do multiple + targets on the same rule yet */ + skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; + nf_tproxy_assign_sock(skb, sk); + return NF_ACCEPT; + } + + return NF_DROP; +} + +static int tproxy_tg6_check(const struct xt_tgchk_param *par) +{ + const struct ip6t_ip6 *i = par->entryinfo; + int err; + + err = nf_defrag_ipv6_enable(par->net); + if (err) + return err; + + if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) && + !(i->invflags & IP6T_INV_PROTO)) + return 0; + + pr_info_ratelimited("Can be used only with -p tcp or -p udp\n"); + return -EINVAL; +} + +static void tproxy_tg6_destroy(const struct xt_tgdtor_param *par) +{ + nf_defrag_ipv6_disable(par->net); +} +#endif + +static int tproxy_tg4_check(const struct xt_tgchk_param *par) +{ + const struct ipt_ip *i = par->entryinfo; + int err; + + err = nf_defrag_ipv4_enable(par->net); + if (err) + return err; + + if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) + && !(i->invflags & IPT_INV_PROTO)) + return 0; + + pr_info_ratelimited("Can be used only with -p tcp or -p udp\n"); + return -EINVAL; +} + +static void tproxy_tg4_destroy(const struct xt_tgdtor_param *par) +{ + nf_defrag_ipv4_disable(par->net); +} + +static struct xt_target tproxy_tg_reg[] __read_mostly = { + { + .name = "TPROXY", + .family = NFPROTO_IPV4, + .table = "mangle", + .target = tproxy_tg4_v0, + .revision = 0, + .targetsize = sizeof(struct xt_tproxy_target_info), + .checkentry = tproxy_tg4_check, + .destroy = tproxy_tg4_destroy, + .hooks = 1 << NF_INET_PRE_ROUTING, + .me = THIS_MODULE, + }, + { + .name = "TPROXY", + .family = NFPROTO_IPV4, + .table = "mangle", + .target = tproxy_tg4_v1, + .revision = 1, + .targetsize = sizeof(struct xt_tproxy_target_info_v1), + .checkentry = tproxy_tg4_check, + .destroy = tproxy_tg4_destroy, + .hooks = 1 << NF_INET_PRE_ROUTING, + .me = THIS_MODULE, + }, +#ifdef XT_TPROXY_HAVE_IPV6 + { + .name = "TPROXY", + .family = NFPROTO_IPV6, + .table = "mangle", + .target = tproxy_tg6_v1, + .revision = 1, + .targetsize = sizeof(struct xt_tproxy_target_info_v1), + .checkentry = tproxy_tg6_check, + .destroy = tproxy_tg6_destroy, + .hooks = 1 << NF_INET_PRE_ROUTING, + .me = THIS_MODULE, + }, +#endif + +}; + +static int __init tproxy_tg_init(void) +{ + return xt_register_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); +} + +static void __exit tproxy_tg_exit(void) +{ + xt_unregister_targets(tproxy_tg_reg, ARRAY_SIZE(tproxy_tg_reg)); +} + +module_init(tproxy_tg_init); +module_exit(tproxy_tg_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); +MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); +MODULE_ALIAS("ipt_TPROXY"); +MODULE_ALIAS("ip6t_TPROXY"); |