--- /dev/null
+/*
+ * Transparent proxy support for Linux/iptables
+ *
+ * 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 <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+#include <net/icmp.h>
+#include <net/sock.h>
+#include <net/inet_sock.h>
+#include <net/netfilter/nf_tproxy_core.h>
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+#define XT_SOCKET_HAVE_CONNTRACK 1
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
+static int
+extract_icmp_fields(const struct sk_buff *skb,
+ u8 *protocol,
+ __be32 *raddr,
+ __be32 *laddr,
+ __be16 *rport,
+ __be16 *lport)
+{
+ unsigned int outside_hdrlen = ip_hdrlen(skb);
+ struct iphdr *inside_iph, _inside_iph;
+ struct icmphdr *icmph, _icmph;
+ __be16 *ports, _ports[2];
+
+ icmph = skb_header_pointer(skb, outside_hdrlen,
+ sizeof(_icmph), &_icmph);
+ if (icmph == NULL)
+ return 1;
+
+ switch (icmph->type) {
+ case ICMP_DEST_UNREACH:
+ case ICMP_SOURCE_QUENCH:
+ case ICMP_REDIRECT:
+ case ICMP_TIME_EXCEEDED:
+ case ICMP_PARAMETERPROB:
+ break;
+ default:
+ return 1;
+ }
+
+ inside_iph = skb_header_pointer(skb, outside_hdrlen +
+ sizeof(struct icmphdr),
+ sizeof(_inside_iph), &_inside_iph);
+ if (inside_iph == NULL)
+ return 1;
+
+ if (inside_iph->protocol != IPPROTO_TCP &&
+ inside_iph->protocol != IPPROTO_UDP)
+ return 1;
+
+ ports = skb_header_pointer(skb, outside_hdrlen +
+ sizeof(struct icmphdr) +
+ (inside_iph->ihl << 2),
+ sizeof(_ports), &_ports);
+ if (ports == NULL)
+ return 1;
+
+ /* the inside IP packet is the one quoted from our side, thus
+ * its saddr is the local address */
+ *protocol = inside_iph->protocol;
+ *laddr = inside_iph->saddr;
+ *lport = ports[0];
+ *raddr = inside_iph->daddr;
+ *rport = ports[1];
+
+ return 0;
+}
+
+
+static bool
+socket_mt(const struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ const struct xt_match *match,
+ const void *matchinfo,
+ int offset,
+ unsigned int protoff,
+ bool *hotdrop)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct udphdr _hdr, *hp = NULL;
+ struct sock *sk;
+ __be32 daddr, saddr;
+ __be16 dport, sport;
+ u8 protocol;
+#ifdef XT_SOCKET_HAVE_CONNTRACK
+ struct nf_conn const *ct;
+ enum ip_conntrack_info ctinfo;
+#endif
+
+ if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
+ hp = skb_header_pointer(skb, ip_hdrlen(skb),
+ sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return false;
+
+ protocol = iph->protocol;
+ saddr = iph->saddr;
+ sport = hp->source;
+ daddr = iph->daddr;
+ dport = hp->dest;
+
+ } else if (iph->protocol == IPPROTO_ICMP) {
+ if (extract_icmp_fields(skb, &protocol, &saddr, &daddr,
+ &sport, &dport))
+ return false;
+ } else {
+ return false;
+ }
+
+#ifdef XT_SOCKET_HAVE_CONNTRACK
+ /* Do the lookup with the original socket address in case this is a
+ * reply packet of an established SNAT-ted connection. */
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct && (ct != &nf_conntrack_untracked) &&
+ ((iph->protocol != IPPROTO_ICMP &&
+ ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) ||
+ (iph->protocol == IPPROTO_ICMP &&
+ ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) &&
+ (ct->status & IPS_SRC_NAT_DONE)) {
+
+ daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
+ dport = (iph->protocol == IPPROTO_TCP) ?
+ ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
+ ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
+ }
+#endif
+
+ sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
+ saddr, daddr, sport, dport, in, false);
+ if (sk != NULL) {
+ bool wildcard = (inet_sk(sk)->rcv_saddr == 0);
+
+ nf_tproxy_put_sock(sk);
+ if (wildcard)
+ sk = NULL;
+ }
+
+ pr_debug("socket match: proto %u %08x:%u -> %08x:%u "
+ "(orig %08x:%u) sock %p\n",
+ protocol, ntohl(saddr), ntohs(sport),
+ ntohl(daddr), ntohs(dport),
+ ntohl(iph->daddr), hp ? ntohs(hp->dest) : 0, sk);
+
+ return (sk != NULL);
+}
+
+static struct xt_match socket_mt_reg __read_mostly = {
+ .name = "socket",
+ .family = AF_INET,
+ .match = socket_mt,
+ .hooks = 1 << NF_INET_PRE_ROUTING,
+ .me = THIS_MODULE,
+};
+
+static int __init socket_mt_init(void)
+{
+ nf_defrag_ipv4_enable();
+ return xt_register_match(&socket_mt_reg);
+}
+
+static void __exit socket_mt_exit(void)
+{
+ xt_unregister_match(&socket_mt_reg);
+}
+
+module_init(socket_mt_init);
+module_exit(socket_mt_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
+MODULE_DESCRIPTION("x_tables socket match module");
+MODULE_ALIAS("ipt_socket");
git.openpandora.org / pandora-kernel.git / blobdiff