1a8bf6eeef
TCP listener refactoring, part 7 : Use sock_gen_put() instead of xt_socket_put_sk() for future SYN_RECV support. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
496 lines
13 KiB
C
496 lines
13 KiB
C
/*
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* Transparent proxy support for Linux/iptables
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*
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* Copyright (C) 2007-2008 BalaBit IT Ltd.
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* Author: Krisztian Kovacs
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#include <net/icmp.h>
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#include <net/sock.h>
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#include <net/inet_sock.h>
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#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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#define XT_SOCKET_HAVE_IPV6 1
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <net/inet6_hashtables.h>
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#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
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#endif
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#include <linux/netfilter/xt_socket.h>
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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#define XT_SOCKET_HAVE_CONNTRACK 1
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#include <net/netfilter/nf_conntrack.h>
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#endif
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static int
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extract_icmp4_fields(const struct sk_buff *skb,
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u8 *protocol,
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__be32 *raddr,
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__be32 *laddr,
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__be16 *rport,
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__be16 *lport)
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{
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unsigned int outside_hdrlen = ip_hdrlen(skb);
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struct iphdr *inside_iph, _inside_iph;
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struct icmphdr *icmph, _icmph;
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__be16 *ports, _ports[2];
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icmph = skb_header_pointer(skb, outside_hdrlen,
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sizeof(_icmph), &_icmph);
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if (icmph == NULL)
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return 1;
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switch (icmph->type) {
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case ICMP_DEST_UNREACH:
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case ICMP_SOURCE_QUENCH:
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case ICMP_REDIRECT:
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case ICMP_TIME_EXCEEDED:
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case ICMP_PARAMETERPROB:
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break;
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default:
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return 1;
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}
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inside_iph = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr),
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sizeof(_inside_iph), &_inside_iph);
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if (inside_iph == NULL)
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return 1;
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if (inside_iph->protocol != IPPROTO_TCP &&
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inside_iph->protocol != IPPROTO_UDP)
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return 1;
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ports = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr) +
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(inside_iph->ihl << 2),
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sizeof(_ports), &_ports);
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if (ports == NULL)
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return 1;
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/* the inside IP packet is the one quoted from our side, thus
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* its saddr is the local address */
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*protocol = inside_iph->protocol;
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*laddr = inside_iph->saddr;
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*lport = ports[0];
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*raddr = inside_iph->daddr;
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*rport = ports[1];
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return 0;
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}
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/* "socket" match based redirection (no specific rule)
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* ===================================================
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*
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* There are connections with dynamic endpoints (e.g. FTP data
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* connection) that the user is unable to add explicit rules
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* for. These are taken care of by a generic "socket" rule. It is
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* assumed that the proxy application is trusted to open such
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* connections without explicit iptables rule (except of course the
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* generic 'socket' rule). In this case the following sockets are
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* matched in preference order:
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*
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* - match: if there's a fully established connection matching the
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* _packet_ tuple
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*
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* - match: if there's a non-zero bound listener (possibly with a
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* non-local address) We don't accept zero-bound listeners, since
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* then local services could intercept traffic going through the
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* box.
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*/
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static struct sock *
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xt_socket_get_sock_v4(struct net *net, const u8 protocol,
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const __be32 saddr, const __be32 daddr,
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const __be16 sport, const __be16 dport,
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const struct net_device *in)
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{
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switch (protocol) {
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case IPPROTO_TCP:
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return __inet_lookup(net, &tcp_hashinfo,
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saddr, sport, daddr, dport,
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in->ifindex);
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case IPPROTO_UDP:
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return udp4_lib_lookup(net, saddr, sport, daddr, dport,
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in->ifindex);
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}
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return NULL;
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}
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static bool
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socket_match(const struct sk_buff *skb, struct xt_action_param *par,
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const struct xt_socket_mtinfo1 *info)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct udphdr _hdr, *hp = NULL;
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struct sock *sk = skb->sk;
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__be32 uninitialized_var(daddr), uninitialized_var(saddr);
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__be16 uninitialized_var(dport), uninitialized_var(sport);
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u8 uninitialized_var(protocol);
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#ifdef XT_SOCKET_HAVE_CONNTRACK
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struct nf_conn const *ct;
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enum ip_conntrack_info ctinfo;
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#endif
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if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
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hp = skb_header_pointer(skb, ip_hdrlen(skb),
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sizeof(_hdr), &_hdr);
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if (hp == NULL)
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return false;
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protocol = iph->protocol;
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saddr = iph->saddr;
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sport = hp->source;
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daddr = iph->daddr;
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dport = hp->dest;
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} else if (iph->protocol == IPPROTO_ICMP) {
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if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
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&sport, &dport))
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return false;
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} else {
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return false;
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}
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#ifdef XT_SOCKET_HAVE_CONNTRACK
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/* Do the lookup with the original socket address in case this is a
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* reply packet of an established SNAT-ted connection. */
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ct = nf_ct_get(skb, &ctinfo);
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if (ct && !nf_ct_is_untracked(ct) &&
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((iph->protocol != IPPROTO_ICMP &&
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ctinfo == IP_CT_ESTABLISHED_REPLY) ||
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(iph->protocol == IPPROTO_ICMP &&
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ctinfo == IP_CT_RELATED_REPLY)) &&
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(ct->status & IPS_SRC_NAT_DONE)) {
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daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
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dport = (iph->protocol == IPPROTO_TCP) ?
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
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}
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#endif
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if (!sk)
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sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol,
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saddr, daddr, sport, dport,
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par->in);
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if (sk) {
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bool wildcard;
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bool transparent = true;
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/* Ignore sockets listening on INADDR_ANY,
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* unless XT_SOCKET_NOWILDCARD is set
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*/
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wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
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sk->sk_state != TCP_TIME_WAIT &&
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inet_sk(sk)->inet_rcv_saddr == 0);
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/* Ignore non-transparent sockets,
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if XT_SOCKET_TRANSPARENT is used */
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if (info->flags & XT_SOCKET_TRANSPARENT)
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transparent = ((sk->sk_state != TCP_TIME_WAIT &&
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inet_sk(sk)->transparent) ||
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(sk->sk_state == TCP_TIME_WAIT &&
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inet_twsk(sk)->tw_transparent));
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if (sk != skb->sk)
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sock_gen_put(sk);
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if (wildcard || !transparent)
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sk = NULL;
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}
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pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
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protocol, &saddr, ntohs(sport),
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&daddr, ntohs(dport),
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&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
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return (sk != NULL);
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}
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static bool
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socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
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{
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static struct xt_socket_mtinfo1 xt_info_v0 = {
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.flags = 0,
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};
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return socket_match(skb, par, &xt_info_v0);
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}
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static bool
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socket_mt4_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
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{
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return socket_match(skb, par, par->matchinfo);
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}
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#ifdef XT_SOCKET_HAVE_IPV6
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static int
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extract_icmp6_fields(const struct sk_buff *skb,
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unsigned int outside_hdrlen,
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int *protocol,
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struct in6_addr **raddr,
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struct in6_addr **laddr,
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__be16 *rport,
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__be16 *lport)
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{
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struct ipv6hdr *inside_iph, _inside_iph;
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struct icmp6hdr *icmph, _icmph;
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__be16 *ports, _ports[2];
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u8 inside_nexthdr;
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__be16 inside_fragoff;
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int inside_hdrlen;
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icmph = skb_header_pointer(skb, outside_hdrlen,
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sizeof(_icmph), &_icmph);
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if (icmph == NULL)
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return 1;
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if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK)
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return 1;
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inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph);
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if (inside_iph == NULL)
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return 1;
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inside_nexthdr = inside_iph->nexthdr;
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inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph),
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&inside_nexthdr, &inside_fragoff);
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if (inside_hdrlen < 0)
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return 1; /* hjm: Packet has no/incomplete transport layer headers. */
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if (inside_nexthdr != IPPROTO_TCP &&
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inside_nexthdr != IPPROTO_UDP)
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return 1;
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ports = skb_header_pointer(skb, inside_hdrlen,
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sizeof(_ports), &_ports);
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if (ports == NULL)
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return 1;
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/* the inside IP packet is the one quoted from our side, thus
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* its saddr is the local address */
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*protocol = inside_nexthdr;
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*laddr = &inside_iph->saddr;
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*lport = ports[0];
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*raddr = &inside_iph->daddr;
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*rport = ports[1];
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return 0;
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}
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static struct sock *
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xt_socket_get_sock_v6(struct net *net, const u8 protocol,
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const struct in6_addr *saddr, const struct in6_addr *daddr,
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const __be16 sport, const __be16 dport,
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const struct net_device *in)
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{
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switch (protocol) {
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case IPPROTO_TCP:
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return inet6_lookup(net, &tcp_hashinfo,
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saddr, sport, daddr, dport,
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in->ifindex);
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case IPPROTO_UDP:
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return udp6_lib_lookup(net, saddr, sport, daddr, dport,
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in->ifindex);
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}
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return NULL;
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}
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static bool
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socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct ipv6hdr *iph = ipv6_hdr(skb);
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struct udphdr _hdr, *hp = NULL;
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struct sock *sk = skb->sk;
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struct in6_addr *daddr = NULL, *saddr = NULL;
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__be16 uninitialized_var(dport), uninitialized_var(sport);
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int thoff = 0, uninitialized_var(tproto);
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const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
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tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
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if (tproto < 0) {
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pr_debug("unable to find transport header in IPv6 packet, dropping\n");
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return NF_DROP;
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}
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if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) {
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hp = skb_header_pointer(skb, thoff,
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sizeof(_hdr), &_hdr);
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if (hp == NULL)
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return false;
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saddr = &iph->saddr;
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sport = hp->source;
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daddr = &iph->daddr;
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dport = hp->dest;
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} else if (tproto == IPPROTO_ICMPV6) {
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if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
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&sport, &dport))
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return false;
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} else {
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return false;
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}
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if (!sk)
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sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto,
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saddr, daddr, sport, dport,
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par->in);
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if (sk) {
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bool wildcard;
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bool transparent = true;
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/* Ignore sockets listening on INADDR_ANY
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* unless XT_SOCKET_NOWILDCARD is set
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*/
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wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
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sk->sk_state != TCP_TIME_WAIT &&
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ipv6_addr_any(&sk->sk_v6_rcv_saddr));
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/* Ignore non-transparent sockets,
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if XT_SOCKET_TRANSPARENT is used */
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if (info->flags & XT_SOCKET_TRANSPARENT)
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transparent = ((sk->sk_state != TCP_TIME_WAIT &&
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inet_sk(sk)->transparent) ||
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(sk->sk_state == TCP_TIME_WAIT &&
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inet_twsk(sk)->tw_transparent));
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if (sk != skb->sk)
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sock_gen_put(sk);
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if (wildcard || !transparent)
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sk = NULL;
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}
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pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
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"(orig %pI6:%hu) sock %p\n",
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tproto, saddr, ntohs(sport),
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daddr, ntohs(dport),
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&iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
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return (sk != NULL);
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}
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#endif
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static int socket_mt_v1_check(const struct xt_mtchk_param *par)
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{
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const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
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if (info->flags & ~XT_SOCKET_FLAGS_V1) {
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pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1);
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return -EINVAL;
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}
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return 0;
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}
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static int socket_mt_v2_check(const struct xt_mtchk_param *par)
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{
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const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
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if (info->flags & ~XT_SOCKET_FLAGS_V2) {
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pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2);
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return -EINVAL;
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}
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return 0;
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}
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static struct xt_match socket_mt_reg[] __read_mostly = {
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{
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.name = "socket",
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.revision = 0,
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.family = NFPROTO_IPV4,
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.match = socket_mt4_v0,
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN),
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.me = THIS_MODULE,
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},
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{
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.name = "socket",
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.revision = 1,
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.family = NFPROTO_IPV4,
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.match = socket_mt4_v1_v2,
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.checkentry = socket_mt_v1_check,
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.matchsize = sizeof(struct xt_socket_mtinfo1),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN),
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.me = THIS_MODULE,
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},
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#ifdef XT_SOCKET_HAVE_IPV6
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{
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.name = "socket",
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.revision = 1,
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.family = NFPROTO_IPV6,
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.match = socket_mt6_v1_v2,
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.checkentry = socket_mt_v1_check,
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.matchsize = sizeof(struct xt_socket_mtinfo1),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN),
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.me = THIS_MODULE,
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},
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#endif
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{
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.name = "socket",
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.revision = 2,
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.family = NFPROTO_IPV4,
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.match = socket_mt4_v1_v2,
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.checkentry = socket_mt_v2_check,
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.matchsize = sizeof(struct xt_socket_mtinfo1),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN),
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.me = THIS_MODULE,
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},
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#ifdef XT_SOCKET_HAVE_IPV6
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{
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.name = "socket",
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.revision = 2,
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.family = NFPROTO_IPV6,
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.match = socket_mt6_v1_v2,
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.checkentry = socket_mt_v2_check,
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.matchsize = sizeof(struct xt_socket_mtinfo1),
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN),
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.me = THIS_MODULE,
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},
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#endif
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};
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static int __init socket_mt_init(void)
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{
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nf_defrag_ipv4_enable();
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#ifdef XT_SOCKET_HAVE_IPV6
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nf_defrag_ipv6_enable();
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#endif
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return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
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}
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static void __exit socket_mt_exit(void)
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{
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xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
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}
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module_init(socket_mt_init);
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module_exit(socket_mt_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
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MODULE_DESCRIPTION("x_tables socket match module");
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MODULE_ALIAS("ipt_socket");
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MODULE_ALIAS("ip6t_socket");
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