From 45ca4e0cf2734f8cc14b43e47c23618215abf1b8 Mon Sep 17 00:00:00 2001 From: Máté Eckl Date: Fri, 1 Jun 2018 20:44:56 +0200 Subject: netfilter: Libify xt_TPROXY MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The extracted functions will likely be usefull to implement tproxy support in nf_tables. Extrancted functions: - nf_tproxy_sk_is_transparent - nf_tproxy_laddr4 - nf_tproxy_handle_time_wait4 - nf_tproxy_get_sock_v4 - nf_tproxy_laddr6 - nf_tproxy_handle_time_wait6 - nf_tproxy_get_sock_v6 (nf_)tproxy_handle_time_wait6 also needed some refactor as its current implementation was xtables-specific. Signed-off-by: Máté Eckl Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/Kconfig | 5 +- net/ipv4/netfilter/Makefile | 1 + net/ipv4/netfilter/nf_tproxy_ipv4.c | 147 ++++++++++++++++++++++++++++++++++++ 3 files changed, 152 insertions(+), 1 deletion(-) create mode 100644 net/ipv4/netfilter/nf_tproxy_ipv4.c (limited to 'net/ipv4') diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig index d03bc5a01a70..bbfc356cb1b5 100644 --- a/net/ipv4/netfilter/Kconfig +++ b/net/ipv4/netfilter/Kconfig @@ -29,7 +29,10 @@ config NF_SOCKET_IPV4 tristate "IPv4 socket lookup support" help This option enables the IPv4 socket lookup infrastructure. This is - is required by the iptables socket match. + is required by the {ip,nf}tables socket match. + +config NF_TPROXY_IPV4 + tristate "IPv4 tproxy support" if NF_TABLES diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile index c4b05b174091..8394c17c269f 100644 --- a/net/ipv4/netfilter/Makefile +++ b/net/ipv4/netfilter/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_NF_NAT_IPV4) += nf_nat_ipv4.o obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o obj-$(CONFIG_NF_SOCKET_IPV4) += nf_socket_ipv4.o +obj-$(CONFIG_NF_TPROXY_IPV4) += nf_tproxy_ipv4.o # logging obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o diff --git a/net/ipv4/netfilter/nf_tproxy_ipv4.c b/net/ipv4/netfilter/nf_tproxy_ipv4.c new file mode 100644 index 000000000000..805e83ec3ad9 --- /dev/null +++ b/net/ipv4/netfilter/nf_tproxy_ipv4.c @@ -0,0 +1,147 @@ +/* + * Copyright (C) 2007-2008 BalaBit IT Ltd. + * Author: Krisztian Kovacs + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct sock * +nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb, + __be32 laddr, __be16 lport, struct sock *sk) +{ + const struct iphdr *iph = ip_hdr(skb); + struct tcphdr _hdr, *hp; + + hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); + if (hp == NULL) { + inet_twsk_put(inet_twsk(sk)); + return NULL; + } + + if (hp->syn && !hp->rst && !hp->ack && !hp->fin) { + /* SYN to a TIME_WAIT socket, we'd rather redirect it + * to a listener socket if there's one */ + struct sock *sk2; + + sk2 = nf_tproxy_get_sock_v4(net, skb, hp, iph->protocol, + iph->saddr, laddr ? laddr : iph->daddr, + hp->source, lport ? lport : hp->dest, + skb->dev, NF_TPROXY_LOOKUP_LISTENER); + if (sk2) { + inet_twsk_deschedule_put(inet_twsk(sk)); + sk = sk2; + } + } + + return sk; +} +EXPORT_SYMBOL_GPL(nf_tproxy_handle_time_wait4); + +__be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr) +{ + struct in_device *indev; + __be32 laddr; + + if (user_laddr) + return user_laddr; + + laddr = 0; + indev = __in_dev_get_rcu(skb->dev); + for_primary_ifa(indev) { + laddr = ifa->ifa_local; + break; + } endfor_ifa(indev); + + return laddr ? laddr : daddr; +} +EXPORT_SYMBOL_GPL(nf_tproxy_laddr4); + +struct sock * +nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb, void *hp, + const u8 protocol, + const __be32 saddr, const __be32 daddr, + const __be16 sport, const __be16 dport, + const struct net_device *in, + const enum nf_tproxy_lookup_t lookup_type) +{ + struct sock *sk; + struct tcphdr *tcph; + + switch (protocol) { + case IPPROTO_TCP: + switch (lookup_type) { + case NF_TPROXY_LOOKUP_LISTENER: + tcph = hp; + sk = inet_lookup_listener(net, &tcp_hashinfo, skb, + ip_hdrlen(skb) + + __tcp_hdrlen(tcph), + saddr, sport, + daddr, dport, + in->ifindex, 0); + + if (sk && !refcount_inc_not_zero(&sk->sk_refcnt)) + sk = NULL; + /* NOTE: we return listeners even if bound to + * 0.0.0.0, those are filtered out in + * xt_socket, since xt_TPROXY needs 0 bound + * listeners too + */ + break; + case NF_TPROXY_LOOKUP_ESTABLISHED: + sk = inet_lookup_established(net, &tcp_hashinfo, + saddr, sport, daddr, dport, + in->ifindex); + break; + default: + BUG(); + } + break; + case IPPROTO_UDP: + sk = udp4_lib_lookup(net, saddr, sport, daddr, dport, + in->ifindex); + if (sk) { + int connected = (sk->sk_state == TCP_ESTABLISHED); + int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0); + + /* NOTE: we return listeners even if bound to + * 0.0.0.0, those are filtered out in + * xt_socket, since xt_TPROXY needs 0 bound + * listeners too + */ + if ((lookup_type == NF_TPROXY_LOOKUP_ESTABLISHED && + (!connected || wildcard)) || + (lookup_type == NF_TPROXY_LOOKUP_LISTENER && connected)) { + sock_put(sk); + sk = NULL; + } + } + break; + default: + WARN_ON(1); + sk = NULL; + } + + pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n", + protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk); + + return sk; +} +EXPORT_SYMBOL_GPL(nf_tproxy_get_sock_v4); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Balazs Scheidler, Krisztian Kovacs"); +MODULE_DESCRIPTION("Netfilter IPv4 transparent proxy support"); -- cgit v1.2.3