mirror of
https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
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402 lines
12 KiB
C
402 lines
12 KiB
C
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/*
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* ip_nat_pptp.c - Version 3.0
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*
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* NAT support for PPTP (Point to Point Tunneling Protocol).
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* PPTP is a a protocol for creating virtual private networks.
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* It is a specification defined by Microsoft and some vendors
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* working with Microsoft. PPTP is built on top of a modified
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* version of the Internet Generic Routing Encapsulation Protocol.
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* GRE is defined in RFC 1701 and RFC 1702. Documentation of
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* PPTP can be found in RFC 2637
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*
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* (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
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*
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* Development of this code funded by Astaro AG (http://www.astaro.com/)
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*
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* TODO: - NAT to a unique tuple, not to TCP source port
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* (needs netfilter tuple reservation)
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*
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* Changes:
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* 2002-02-10 - Version 1.3
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* - Use ip_nat_mangle_tcp_packet() because of cloned skb's
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* in local connections (Philip Craig <philipc@snapgear.com>)
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* - add checks for magicCookie and pptp version
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* - make argument list of pptp_{out,in}bound_packet() shorter
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* - move to C99 style initializers
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* - print version number at module loadtime
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* 2003-09-22 - Version 1.5
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* - use SNATed tcp sourceport as callid, since we get called before
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* TCP header is mangled (Philip Craig <philipc@snapgear.com>)
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* 2004-10-22 - Version 2.0
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* - kernel 2.6.x version
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* 2005-06-10 - Version 3.0
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* - kernel >= 2.6.11 version,
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* funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
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*
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <net/tcp.h>
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_nat_pptp.h>
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#include <linux/netfilter_ipv4/ip_conntrack_core.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h>
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#include <linux/netfilter_ipv4/ip_conntrack_pptp.h>
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#define IP_NAT_PPTP_VERSION "3.0"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
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MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP");
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#if 0
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extern const char *pptp_msg_name[];
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#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \
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__FUNCTION__, ## args)
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#else
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#define DEBUGP(format, args...)
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#endif
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static void pptp_nat_expected(struct ip_conntrack *ct,
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struct ip_conntrack_expect *exp)
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{
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struct ip_conntrack *master = ct->master;
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struct ip_conntrack_expect *other_exp;
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struct ip_conntrack_tuple t;
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struct ip_ct_pptp_master *ct_pptp_info;
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struct ip_nat_pptp *nat_pptp_info;
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ct_pptp_info = &master->help.ct_pptp_info;
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nat_pptp_info = &master->nat.help.nat_pptp_info;
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/* And here goes the grand finale of corrosion... */
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if (exp->dir == IP_CT_DIR_ORIGINAL) {
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DEBUGP("we are PNS->PAC\n");
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/* therefore, build tuple for PAC->PNS */
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t.src.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip;
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t.src.u.gre.key = htons(master->help.ct_pptp_info.pac_call_id);
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t.dst.ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
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t.dst.u.gre.key = htons(master->help.ct_pptp_info.pns_call_id);
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t.dst.protonum = IPPROTO_GRE;
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} else {
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DEBUGP("we are PAC->PNS\n");
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/* build tuple for PNS->PAC */
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t.src.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
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t.src.u.gre.key =
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htons(master->nat.help.nat_pptp_info.pns_call_id);
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t.dst.ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip;
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t.dst.u.gre.key =
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htons(master->nat.help.nat_pptp_info.pac_call_id);
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t.dst.protonum = IPPROTO_GRE;
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}
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DEBUGP("trying to unexpect other dir: ");
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DUMP_TUPLE(&t);
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other_exp = ip_conntrack_expect_find(&t);
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if (other_exp) {
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ip_conntrack_unexpect_related(other_exp);
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ip_conntrack_expect_put(other_exp);
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DEBUGP("success\n");
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} else {
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DEBUGP("not found!\n");
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}
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ip_nat_follow_master(ct, exp);
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}
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/* outbound packets == from PNS to PAC */
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static int
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pptp_outbound_pkt(struct sk_buff **pskb,
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struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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struct PptpControlHeader *ctlh,
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union pptp_ctrl_union *pptpReq)
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{
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struct ip_ct_pptp_master *ct_pptp_info = &ct->help.ct_pptp_info;
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struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
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u_int16_t msg, *cid = NULL, new_callid;
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new_callid = htons(ct_pptp_info->pns_call_id);
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switch (msg = ntohs(ctlh->messageType)) {
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case PPTP_OUT_CALL_REQUEST:
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cid = &pptpReq->ocreq.callID;
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/* FIXME: ideally we would want to reserve a call ID
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* here. current netfilter NAT core is not able to do
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* this :( For now we use TCP source port. This breaks
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* multiple calls within one control session */
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/* save original call ID in nat_info */
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nat_pptp_info->pns_call_id = ct_pptp_info->pns_call_id;
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/* don't use tcph->source since we are at a DSTmanip
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* hook (e.g. PREROUTING) and pkt is not mangled yet */
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new_callid = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port;
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/* save new call ID in ct info */
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ct_pptp_info->pns_call_id = ntohs(new_callid);
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break;
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case PPTP_IN_CALL_REPLY:
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cid = &pptpReq->icreq.callID;
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break;
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case PPTP_CALL_CLEAR_REQUEST:
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cid = &pptpReq->clrreq.callID;
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break;
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default:
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DEBUGP("unknown outbound packet 0x%04x:%s\n", msg,
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(msg <= PPTP_MSG_MAX)?
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pptp_msg_name[msg]:pptp_msg_name[0]);
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/* fall through */
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case PPTP_SET_LINK_INFO:
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/* only need to NAT in case PAC is behind NAT box */
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case PPTP_START_SESSION_REQUEST:
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case PPTP_START_SESSION_REPLY:
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case PPTP_STOP_SESSION_REQUEST:
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case PPTP_STOP_SESSION_REPLY:
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case PPTP_ECHO_REQUEST:
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case PPTP_ECHO_REPLY:
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/* no need to alter packet */
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return NF_ACCEPT;
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}
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/* only OUT_CALL_REQUEST, IN_CALL_REPLY, CALL_CLEAR_REQUEST pass
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* down to here */
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IP_NF_ASSERT(cid);
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DEBUGP("altering call id from 0x%04x to 0x%04x\n",
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ntohs(*cid), ntohs(new_callid));
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/* mangle packet */
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if (ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
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(void *)cid - ((void *)ctlh - sizeof(struct pptp_pkt_hdr)),
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sizeof(new_callid),
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(char *)&new_callid,
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sizeof(new_callid)) == 0)
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return NF_DROP;
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return NF_ACCEPT;
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}
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static int
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pptp_exp_gre(struct ip_conntrack_expect *expect_orig,
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struct ip_conntrack_expect *expect_reply)
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{
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struct ip_ct_pptp_master *ct_pptp_info =
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&expect_orig->master->help.ct_pptp_info;
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struct ip_nat_pptp *nat_pptp_info =
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&expect_orig->master->nat.help.nat_pptp_info;
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struct ip_conntrack *ct = expect_orig->master;
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struct ip_conntrack_tuple inv_t;
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struct ip_conntrack_tuple *orig_t, *reply_t;
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/* save original PAC call ID in nat_info */
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nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id;
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/* alter expectation */
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orig_t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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reply_t = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
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/* alter expectation for PNS->PAC direction */
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invert_tuplepr(&inv_t, &expect_orig->tuple);
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expect_orig->saved_proto.gre.key = htons(nat_pptp_info->pac_call_id);
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expect_orig->tuple.src.u.gre.key = htons(nat_pptp_info->pns_call_id);
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expect_orig->tuple.dst.u.gre.key = htons(ct_pptp_info->pac_call_id);
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inv_t.src.ip = reply_t->src.ip;
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inv_t.dst.ip = reply_t->dst.ip;
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inv_t.src.u.gre.key = htons(nat_pptp_info->pac_call_id);
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inv_t.dst.u.gre.key = htons(ct_pptp_info->pns_call_id);
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if (!ip_conntrack_expect_related(expect_orig)) {
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DEBUGP("successfully registered expect\n");
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} else {
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DEBUGP("can't expect_related(expect_orig)\n");
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return 1;
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}
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/* alter expectation for PAC->PNS direction */
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invert_tuplepr(&inv_t, &expect_reply->tuple);
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expect_reply->saved_proto.gre.key = htons(nat_pptp_info->pns_call_id);
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expect_reply->tuple.src.u.gre.key = htons(nat_pptp_info->pac_call_id);
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expect_reply->tuple.dst.u.gre.key = htons(ct_pptp_info->pns_call_id);
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inv_t.src.ip = orig_t->src.ip;
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inv_t.dst.ip = orig_t->dst.ip;
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inv_t.src.u.gre.key = htons(nat_pptp_info->pns_call_id);
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inv_t.dst.u.gre.key = htons(ct_pptp_info->pac_call_id);
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if (!ip_conntrack_expect_related(expect_reply)) {
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DEBUGP("successfully registered expect\n");
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} else {
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DEBUGP("can't expect_related(expect_reply)\n");
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ip_conntrack_unexpect_related(expect_orig);
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return 1;
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}
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if (ip_ct_gre_keymap_add(ct, &expect_reply->tuple, 0) < 0) {
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DEBUGP("can't register original keymap\n");
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ip_conntrack_unexpect_related(expect_orig);
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ip_conntrack_unexpect_related(expect_reply);
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return 1;
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}
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if (ip_ct_gre_keymap_add(ct, &inv_t, 1) < 0) {
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DEBUGP("can't register reply keymap\n");
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ip_conntrack_unexpect_related(expect_orig);
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ip_conntrack_unexpect_related(expect_reply);
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ip_ct_gre_keymap_destroy(ct);
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return 1;
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}
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return 0;
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}
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/* inbound packets == from PAC to PNS */
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static int
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pptp_inbound_pkt(struct sk_buff **pskb,
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struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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struct PptpControlHeader *ctlh,
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union pptp_ctrl_union *pptpReq)
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{
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struct ip_nat_pptp *nat_pptp_info = &ct->nat.help.nat_pptp_info;
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u_int16_t msg, new_cid = 0, new_pcid, *pcid = NULL, *cid = NULL;
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int ret = NF_ACCEPT, rv;
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new_pcid = htons(nat_pptp_info->pns_call_id);
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switch (msg = ntohs(ctlh->messageType)) {
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case PPTP_OUT_CALL_REPLY:
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pcid = &pptpReq->ocack.peersCallID;
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cid = &pptpReq->ocack.callID;
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break;
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case PPTP_IN_CALL_CONNECT:
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pcid = &pptpReq->iccon.peersCallID;
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break;
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case PPTP_IN_CALL_REQUEST:
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/* only need to nat in case PAC is behind NAT box */
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break;
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case PPTP_WAN_ERROR_NOTIFY:
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pcid = &pptpReq->wanerr.peersCallID;
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break;
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case PPTP_CALL_DISCONNECT_NOTIFY:
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pcid = &pptpReq->disc.callID;
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break;
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case PPTP_SET_LINK_INFO:
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pcid = &pptpReq->setlink.peersCallID;
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break;
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default:
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DEBUGP("unknown inbound packet %s\n", (msg <= PPTP_MSG_MAX)?
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pptp_msg_name[msg]:pptp_msg_name[0]);
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/* fall through */
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case PPTP_START_SESSION_REQUEST:
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case PPTP_START_SESSION_REPLY:
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case PPTP_STOP_SESSION_REQUEST:
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case PPTP_STOP_SESSION_REPLY:
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case PPTP_ECHO_REQUEST:
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case PPTP_ECHO_REPLY:
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/* no need to alter packet */
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return NF_ACCEPT;
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}
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/* only OUT_CALL_REPLY, IN_CALL_CONNECT, IN_CALL_REQUEST,
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* WAN_ERROR_NOTIFY, CALL_DISCONNECT_NOTIFY pass down here */
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/* mangle packet */
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IP_NF_ASSERT(pcid);
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DEBUGP("altering peer call id from 0x%04x to 0x%04x\n",
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ntohs(*pcid), ntohs(new_pcid));
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rv = ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
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(void *)pcid - ((void *)ctlh - sizeof(struct pptp_pkt_hdr)),
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sizeof(new_pcid), (char *)&new_pcid,
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sizeof(new_pcid));
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if (rv != NF_ACCEPT)
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return rv;
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if (new_cid) {
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IP_NF_ASSERT(cid);
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DEBUGP("altering call id from 0x%04x to 0x%04x\n",
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ntohs(*cid), ntohs(new_cid));
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rv = ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
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(void *)cid - ((void *)ctlh - sizeof(struct pptp_pkt_hdr)),
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sizeof(new_cid),
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(char *)&new_cid,
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sizeof(new_cid));
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if (rv != NF_ACCEPT)
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return rv;
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}
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/* check for earlier return value of 'switch' above */
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if (ret != NF_ACCEPT)
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return ret;
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/* great, at least we don't need to resize packets */
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return NF_ACCEPT;
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}
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extern int __init ip_nat_proto_gre_init(void);
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extern void __exit ip_nat_proto_gre_fini(void);
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static int __init init(void)
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{
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int ret;
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DEBUGP("%s: registering NAT helper\n", __FILE__);
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ret = ip_nat_proto_gre_init();
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if (ret < 0)
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return ret;
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BUG_ON(ip_nat_pptp_hook_outbound);
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ip_nat_pptp_hook_outbound = &pptp_outbound_pkt;
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BUG_ON(ip_nat_pptp_hook_inbound);
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ip_nat_pptp_hook_inbound = &pptp_inbound_pkt;
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BUG_ON(ip_nat_pptp_hook_exp_gre);
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ip_nat_pptp_hook_exp_gre = &pptp_exp_gre;
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BUG_ON(ip_nat_pptp_hook_expectfn);
|
||
|
ip_nat_pptp_hook_expectfn = &pptp_nat_expected;
|
||
|
|
||
|
printk("ip_nat_pptp version %s loaded\n", IP_NAT_PPTP_VERSION);
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static void __exit fini(void)
|
||
|
{
|
||
|
DEBUGP("cleanup_module\n" );
|
||
|
|
||
|
ip_nat_pptp_hook_expectfn = NULL;
|
||
|
ip_nat_pptp_hook_exp_gre = NULL;
|
||
|
ip_nat_pptp_hook_inbound = NULL;
|
||
|
ip_nat_pptp_hook_outbound = NULL;
|
||
|
|
||
|
ip_nat_proto_gre_fini();
|
||
|
/* Make sure noone calls it, meanwhile */
|
||
|
synchronize_net();
|
||
|
|
||
|
printk("ip_nat_pptp version %s unloaded\n", IP_NAT_PPTP_VERSION);
|
||
|
}
|
||
|
|
||
|
module_init(init);
|
||
|
module_exit(fini);
|