--- /dev/null
+/*
+ * ip_conntrack_pptp.c - Version 3.0
+ *
+ * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
+ * PPTP is a a protocol for creating virtual private networks.
+ * It is a specification defined by Microsoft and some vendors
+ * working with Microsoft. PPTP is built on top of a modified
+ * version of the Internet Generic Routing Encapsulation Protocol.
+ * GRE is defined in RFC 1701 and RFC 1702. Documentation of
+ * PPTP can be found in RFC 2637
+ *
+ * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ *
+ * Limitations:
+ * - We blindly assume that control connections are always
+ * established in PNS->PAC direction. This is a violation
+ * of RFFC2673
+ * - We can only support one single call within each session
+ *
+ * TODO:
+ * - testing of incoming PPTP calls
+ *
+ * Changes:
+ * 2002-02-05 - Version 1.3
+ * - Call ip_conntrack_unexpect_related() from
+ * pptp_destroy_siblings() to destroy expectations in case
+ * CALL_DISCONNECT_NOTIFY or tcp fin packet was seen
+ * (Philip Craig <philipc@snapgear.com>)
+ * - Add Version information at module loadtime
+ * 2002-02-10 - Version 1.6
+ * - move to C99 style initializers
+ * - remove second expectation if first arrives
+ * 2004-10-22 - Version 2.0
+ * - merge Mandrake's 2.6.x port with recent 2.6.x API changes
+ * - fix lots of linear skb assumptions from Mandrake's port
+ * 2005-06-10 - Version 2.1
+ * - use ip_conntrack_expect_free() instead of kfree() on the
+ * expect's (which are from the slab for quite some time)
+ * 2005-06-10 - Version 3.0
+ * - port helper to post-2.6.11 API changes,
+ * funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
+ * 2005-07-30 - Version 3.1
+ * - port helper to 2.6.13 API changes
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/ip.h>
+#include <net/checksum.h>
+#include <net/tcp.h>
+
+#include <linux/netfilter_ipv4/ip_conntrack.h>
+#include <linux/netfilter_ipv4/ip_conntrack_core.h>
+#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
+#include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h>
+#include <linux/netfilter_ipv4/ip_conntrack_pptp.h>
+
+#define IP_CT_PPTP_VERSION "3.1"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
+MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
+
+static DEFINE_SPINLOCK(ip_pptp_lock);
+
+int
+(*ip_nat_pptp_hook_outbound)(struct sk_buff **pskb,
+ struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ struct PptpControlHeader *ctlh,
+ union pptp_ctrl_union *pptpReq);
+
+int
+(*ip_nat_pptp_hook_inbound)(struct sk_buff **pskb,
+ struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ struct PptpControlHeader *ctlh,
+ union pptp_ctrl_union *pptpReq);
+
+int
+(*ip_nat_pptp_hook_exp_gre)(struct ip_conntrack_expect *expect_orig,
+ struct ip_conntrack_expect *expect_reply);
+
+void
+(*ip_nat_pptp_hook_expectfn)(struct ip_conntrack *ct,
+ struct ip_conntrack_expect *exp);
+
+#if 0
+/* PptpControlMessageType names */
+const char *pptp_msg_name[] = {
+ "UNKNOWN_MESSAGE",
+ "START_SESSION_REQUEST",
+ "START_SESSION_REPLY",
+ "STOP_SESSION_REQUEST",
+ "STOP_SESSION_REPLY",
+ "ECHO_REQUEST",
+ "ECHO_REPLY",
+ "OUT_CALL_REQUEST",
+ "OUT_CALL_REPLY",
+ "IN_CALL_REQUEST",
+ "IN_CALL_REPLY",
+ "IN_CALL_CONNECT",
+ "CALL_CLEAR_REQUEST",
+ "CALL_DISCONNECT_NOTIFY",
+ "WAN_ERROR_NOTIFY",
+ "SET_LINK_INFO"
+};
+EXPORT_SYMBOL(pptp_msg_name);
+#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
+#else
+#define DEBUGP(format, args...)
+#endif
+
+#define SECS *HZ
+#define MINS * 60 SECS
+#define HOURS * 60 MINS
+
+#define PPTP_GRE_TIMEOUT (10 MINS)
+#define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
+
+static void pptp_expectfn(struct ip_conntrack *ct,
+ struct ip_conntrack_expect *exp)
+{
+ DEBUGP("increasing timeouts\n");
+
+ /* increase timeout of GRE data channel conntrack entry */
+ ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
+ ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
+
+ /* Can you see how rusty this code is, compared with the pre-2.6.11
+ * one? That's what happened to my shiny newnat of 2002 ;( -HW */
+
+ if (!ip_nat_pptp_hook_expectfn) {
+ struct ip_conntrack_tuple inv_t;
+ struct ip_conntrack_expect *exp_other;
+
+ /* obviously this tuple inversion only works until you do NAT */
+ invert_tuplepr(&inv_t, &exp->tuple);
+ DEBUGP("trying to unexpect other dir: ");
+ DUMP_TUPLE(&inv_t);
+
+ exp_other = ip_conntrack_expect_find(&inv_t);
+ if (exp_other) {
+ /* delete other expectation. */
+ DEBUGP("found\n");
+ ip_conntrack_unexpect_related(exp_other);
+ ip_conntrack_expect_put(exp_other);
+ } else {
+ DEBUGP("not found\n");
+ }
+ } else {
+ /* we need more than simple inversion */
+ ip_nat_pptp_hook_expectfn(ct, exp);
+ }
+}
+
+static int destroy_sibling_or_exp(const struct ip_conntrack_tuple *t)
+{
+ struct ip_conntrack_tuple_hash *h;
+ struct ip_conntrack_expect *exp;
+
+ DEBUGP("trying to timeout ct or exp for tuple ");
+ DUMP_TUPLE(t);
+
+ h = ip_conntrack_find_get(t, NULL);
+ if (h) {
+ struct ip_conntrack *sibling = tuplehash_to_ctrack(h);
+ DEBUGP("setting timeout of conntrack %p to 0\n", sibling);
+ sibling->proto.gre.timeout = 0;
+ sibling->proto.gre.stream_timeout = 0;
+ if (del_timer(&sibling->timeout))
+ sibling->timeout.function((unsigned long)sibling);
+ ip_conntrack_put(sibling);
+ return 1;
+ } else {
+ exp = ip_conntrack_expect_find(t);
+ if (exp) {
+ DEBUGP("unexpect_related of expect %p\n", exp);
+ ip_conntrack_unexpect_related(exp);
+ ip_conntrack_expect_put(exp);
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+
+/* timeout GRE data connections */
+static void pptp_destroy_siblings(struct ip_conntrack *ct)
+{
+ struct ip_conntrack_tuple t;
+
+ /* Since ct->sibling_list has literally rusted away in 2.6.11,
+ * we now need another way to find out about our sibling
+ * contrack and expects... -HW */
+
+ /* try original (pns->pac) tuple */
+ memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
+ t.dst.protonum = IPPROTO_GRE;
+ t.src.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id);
+ t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id);
+
+ if (!destroy_sibling_or_exp(&t))
+ DEBUGP("failed to timeout original pns->pac ct/exp\n");
+
+ /* try reply (pac->pns) tuple */
+ memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
+ t.dst.protonum = IPPROTO_GRE;
+ t.src.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id);
+ t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id);
+
+ if (!destroy_sibling_or_exp(&t))
+ DEBUGP("failed to timeout reply pac->pns ct/exp\n");
+}
+
+/* expect GRE connections (PNS->PAC and PAC->PNS direction) */
+static inline int
+exp_gre(struct ip_conntrack *master,
+ u_int32_t seq,
+ __be16 callid,
+ __be16 peer_callid)
+{
+ struct ip_conntrack_tuple inv_tuple;
+ struct ip_conntrack_tuple exp_tuples[] = {
+ /* tuple in original direction, PNS->PAC */
+ { .src = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip,
+ .u = { .gre = { .key = peer_callid } }
+ },
+ .dst = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip,
+ .u = { .gre = { .key = callid } },
+ .protonum = IPPROTO_GRE
+ },
+ },
+ /* tuple in reply direction, PAC->PNS */
+ { .src = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip,
+ .u = { .gre = { .key = callid } }
+ },
+ .dst = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip,
+ .u = { .gre = { .key = peer_callid } },
+ .protonum = IPPROTO_GRE
+ },
+ }
+ };
+ struct ip_conntrack_expect *exp_orig, *exp_reply;
+ int ret = 1;
+
+ exp_orig = ip_conntrack_expect_alloc(master);
+ if (exp_orig == NULL)
+ goto out;
+
+ exp_reply = ip_conntrack_expect_alloc(master);
+ if (exp_reply == NULL)
+ goto out_put_orig;
+
+ memcpy(&exp_orig->tuple, &exp_tuples[0], sizeof(exp_orig->tuple));
+
+ exp_orig->mask.src.ip = 0xffffffff;
+ exp_orig->mask.src.u.all = 0;
+ exp_orig->mask.dst.u.all = 0;
+ exp_orig->mask.dst.u.gre.key = htons(0xffff);
+ exp_orig->mask.dst.ip = 0xffffffff;
+ exp_orig->mask.dst.protonum = 0xff;
+
+ exp_orig->master = master;
+ exp_orig->expectfn = pptp_expectfn;
+ exp_orig->flags = 0;
+
+ /* both expectations are identical apart from tuple */
+ memcpy(exp_reply, exp_orig, sizeof(*exp_reply));
+ memcpy(&exp_reply->tuple, &exp_tuples[1], sizeof(exp_reply->tuple));
+
+ if (ip_nat_pptp_hook_exp_gre)
+ ret = ip_nat_pptp_hook_exp_gre(exp_orig, exp_reply);
+ else {
+
+ DEBUGP("calling expect_related PNS->PAC");
+ DUMP_TUPLE(&exp_orig->tuple);
+
+ if (ip_conntrack_expect_related(exp_orig) != 0) {
+ DEBUGP("cannot expect_related()\n");
+ goto out_put_both;
+ }
+
+ DEBUGP("calling expect_related PAC->PNS");
+ DUMP_TUPLE(&exp_reply->tuple);
+
+ if (ip_conntrack_expect_related(exp_reply) != 0) {
+ DEBUGP("cannot expect_related()\n");
+ goto out_unexpect_orig;
+ }
+
+ /* Add GRE keymap entries */
+ if (ip_ct_gre_keymap_add(master, &exp_reply->tuple, 0) != 0) {
+ DEBUGP("cannot keymap_add() exp\n");
+ goto out_unexpect_both;
+ }
+
+ invert_tuplepr(&inv_tuple, &exp_reply->tuple);
+ if (ip_ct_gre_keymap_add(master, &inv_tuple, 1) != 0) {
+ ip_ct_gre_keymap_destroy(master);
+ DEBUGP("cannot keymap_add() exp_inv\n");
+ goto out_unexpect_both;
+ }
+ ret = 0;
+ }
+
+out_put_both:
+ ip_conntrack_expect_put(exp_reply);
+out_put_orig:
+ ip_conntrack_expect_put(exp_orig);
+out:
+ return ret;
+
+out_unexpect_both:
+ ip_conntrack_unexpect_related(exp_reply);
+out_unexpect_orig:
+ ip_conntrack_unexpect_related(exp_orig);
+ goto out_put_both;
+}
+
+static inline int
+pptp_inbound_pkt(struct sk_buff **pskb,
+ struct tcphdr *tcph,
+ unsigned int nexthdr_off,
+ unsigned int datalen,
+ struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ struct PptpControlHeader _ctlh, *ctlh;
+ unsigned int reqlen;
+ union pptp_ctrl_union _pptpReq, *pptpReq;
+ struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
+ u_int16_t msg;
+ __be16 *cid, *pcid;
+ u_int32_t seq;
+
+ ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
+ if (!ctlh) {
+ DEBUGP("error during skb_header_pointer\n");
+ return NF_ACCEPT;
+ }
+ nexthdr_off += sizeof(_ctlh);
+ datalen -= sizeof(_ctlh);
+
+ reqlen = datalen;
+ if (reqlen > sizeof(*pptpReq))
+ reqlen = sizeof(*pptpReq);
+ pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
+ if (!pptpReq) {
+ DEBUGP("error during skb_header_pointer\n");
+ return NF_ACCEPT;
+ }
+
+ msg = ntohs(ctlh->messageType);
+ DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
+
+ switch (msg) {
+ case PPTP_START_SESSION_REPLY:
+ if (reqlen < sizeof(_pptpReq.srep)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server confirms new control session */
+ if (info->sstate < PPTP_SESSION_REQUESTED) {
+ DEBUGP("%s without START_SESS_REQUEST\n",
+ pptp_msg_name[msg]);
+ break;
+ }
+ if (pptpReq->srep.resultCode == PPTP_START_OK)
+ info->sstate = PPTP_SESSION_CONFIRMED;
+ else
+ info->sstate = PPTP_SESSION_ERROR;
+ break;
+
+ case PPTP_STOP_SESSION_REPLY:
+ if (reqlen < sizeof(_pptpReq.strep)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server confirms end of control session */
+ if (info->sstate > PPTP_SESSION_STOPREQ) {
+ DEBUGP("%s without STOP_SESS_REQUEST\n",
+ pptp_msg_name[msg]);
+ break;
+ }
+ if (pptpReq->strep.resultCode == PPTP_STOP_OK)
+ info->sstate = PPTP_SESSION_NONE;
+ else
+ info->sstate = PPTP_SESSION_ERROR;
+ break;
+
+ case PPTP_OUT_CALL_REPLY:
+ if (reqlen < sizeof(_pptpReq.ocack)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server accepted call, we now expect GRE frames */
+ if (info->sstate != PPTP_SESSION_CONFIRMED) {
+ DEBUGP("%s but no session\n", pptp_msg_name[msg]);
+ break;
+ }
+ if (info->cstate != PPTP_CALL_OUT_REQ &&
+ info->cstate != PPTP_CALL_OUT_CONF) {
+ DEBUGP("%s without OUTCALL_REQ\n", pptp_msg_name[msg]);
+ break;
+ }
+ if (pptpReq->ocack.resultCode != PPTP_OUTCALL_CONNECT) {
+ info->cstate = PPTP_CALL_NONE;
+ break;
+ }
+
+ cid = &pptpReq->ocack.callID;
+ pcid = &pptpReq->ocack.peersCallID;
+
+ info->pac_call_id = ntohs(*cid);
+
+ if (htons(info->pns_call_id) != *pcid) {
+ DEBUGP("%s for unknown callid %u\n",
+ pptp_msg_name[msg], ntohs(*pcid));
+ break;
+ }
+
+ DEBUGP("%s, CID=%X, PCID=%X\n", pptp_msg_name[msg],
+ ntohs(*cid), ntohs(*pcid));
+
+ info->cstate = PPTP_CALL_OUT_CONF;
+
+ seq = ntohl(tcph->seq) + sizeof(struct pptp_pkt_hdr)
+ + sizeof(struct PptpControlHeader)
+ + ((void *)pcid - (void *)pptpReq);
+
+ if (exp_gre(ct, seq, *cid, *pcid) != 0)
+ printk("ip_conntrack_pptp: error during exp_gre\n");
+ break;
+
+ case PPTP_IN_CALL_REQUEST:
+ if (reqlen < sizeof(_pptpReq.icack)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server tells us about incoming call request */
+ if (info->sstate != PPTP_SESSION_CONFIRMED) {
+ DEBUGP("%s but no session\n", pptp_msg_name[msg]);
+ break;
+ }
+ pcid = &pptpReq->icack.peersCallID;
+ DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(*pcid));
+ info->cstate = PPTP_CALL_IN_REQ;
+ info->pac_call_id = ntohs(*pcid);
+ break;
+
+ case PPTP_IN_CALL_CONNECT:
+ if (reqlen < sizeof(_pptpReq.iccon)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server tells us about incoming call established */
+ if (info->sstate != PPTP_SESSION_CONFIRMED) {
+ DEBUGP("%s but no session\n", pptp_msg_name[msg]);
+ break;
+ }
+ if (info->cstate != PPTP_CALL_IN_REP
+ && info->cstate != PPTP_CALL_IN_CONF) {
+ DEBUGP("%s but never sent IN_CALL_REPLY\n",
+ pptp_msg_name[msg]);
+ break;
+ }
+
+ pcid = &pptpReq->iccon.peersCallID;
+ cid = &info->pac_call_id;
+
+ if (info->pns_call_id != ntohs(*pcid)) {
+ DEBUGP("%s for unknown CallID %u\n",
+ pptp_msg_name[msg], ntohs(*pcid));
+ break;
+ }
+
+ DEBUGP("%s, PCID=%X\n", pptp_msg_name[msg], ntohs(*pcid));
+ info->cstate = PPTP_CALL_IN_CONF;
+
+ /* we expect a GRE connection from PAC to PNS */
+ seq = ntohl(tcph->seq) + sizeof(struct pptp_pkt_hdr)
+ + sizeof(struct PptpControlHeader)
+ + ((void *)pcid - (void *)pptpReq);
+
+ if (exp_gre(ct, seq, *cid, *pcid) != 0)
+ printk("ip_conntrack_pptp: error during exp_gre\n");
+
+ break;
+
+ case PPTP_CALL_DISCONNECT_NOTIFY:
+ if (reqlen < sizeof(_pptpReq.disc)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* server confirms disconnect */
+ cid = &pptpReq->disc.callID;
+ DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*cid));
+ info->cstate = PPTP_CALL_NONE;
+
+ /* untrack this call id, unexpect GRE packets */
+ pptp_destroy_siblings(ct);
+ break;
+
+ case PPTP_WAN_ERROR_NOTIFY:
+ break;
+
+ case PPTP_ECHO_REQUEST:
+ case PPTP_ECHO_REPLY:
+ /* I don't have to explain these ;) */
+ break;
+ default:
+ DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX)
+ ? pptp_msg_name[msg]:pptp_msg_name[0], msg);
+ break;
+ }
+
+
+ if (ip_nat_pptp_hook_inbound)
+ return ip_nat_pptp_hook_inbound(pskb, ct, ctinfo, ctlh,
+ pptpReq);
+
+ return NF_ACCEPT;
+
+}
+
+static inline int
+pptp_outbound_pkt(struct sk_buff **pskb,
+ struct tcphdr *tcph,
+ unsigned int nexthdr_off,
+ unsigned int datalen,
+ struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ struct PptpControlHeader _ctlh, *ctlh;
+ unsigned int reqlen;
+ union pptp_ctrl_union _pptpReq, *pptpReq;
+ struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
+ u_int16_t msg;
+ __be16 *cid, *pcid;
+
+ ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
+ if (!ctlh)
+ return NF_ACCEPT;
+ nexthdr_off += sizeof(_ctlh);
+ datalen -= sizeof(_ctlh);
+
+ reqlen = datalen;
+ if (reqlen > sizeof(*pptpReq))
+ reqlen = sizeof(*pptpReq);
+ pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
+ if (!pptpReq)
+ return NF_ACCEPT;
+
+ msg = ntohs(ctlh->messageType);
+ DEBUGP("outbound control message %s\n", pptp_msg_name[msg]);
+
+ switch (msg) {
+ case PPTP_START_SESSION_REQUEST:
+ /* client requests for new control session */
+ if (info->sstate != PPTP_SESSION_NONE) {
+ DEBUGP("%s but we already have one",
+ pptp_msg_name[msg]);
+ }
+ info->sstate = PPTP_SESSION_REQUESTED;
+ break;
+ case PPTP_STOP_SESSION_REQUEST:
+ /* client requests end of control session */
+ info->sstate = PPTP_SESSION_STOPREQ;
+ break;
+
+ case PPTP_OUT_CALL_REQUEST:
+ if (reqlen < sizeof(_pptpReq.ocreq)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ /* FIXME: break; */
+ }
+
+ /* client initiating connection to server */
+ if (info->sstate != PPTP_SESSION_CONFIRMED) {
+ DEBUGP("%s but no session\n",
+ pptp_msg_name[msg]);
+ break;
+ }
+ info->cstate = PPTP_CALL_OUT_REQ;
+ /* track PNS call id */
+ cid = &pptpReq->ocreq.callID;
+ DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*cid));
+ info->pns_call_id = ntohs(*cid);
+ break;
+ case PPTP_IN_CALL_REPLY:
+ if (reqlen < sizeof(_pptpReq.icack)) {
+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
+ break;
+ }
+
+ /* client answers incoming call */
+ if (info->cstate != PPTP_CALL_IN_REQ
+ && info->cstate != PPTP_CALL_IN_REP) {
+ DEBUGP("%s without incall_req\n",
+ pptp_msg_name[msg]);
+ break;
+ }
+ if (pptpReq->icack.resultCode != PPTP_INCALL_ACCEPT) {
+ info->cstate = PPTP_CALL_NONE;
+ break;
+ }
+ pcid = &pptpReq->icack.peersCallID;
+ if (info->pac_call_id != ntohs(*pcid)) {
+ DEBUGP("%s for unknown call %u\n",
+ pptp_msg_name[msg], ntohs(*pcid));
+ break;
+ }
+ DEBUGP("%s, CID=%X\n", pptp_msg_name[msg], ntohs(*pcid));
+ /* part two of the three-way handshake */
+ info->cstate = PPTP_CALL_IN_REP;
+ info->pns_call_id = ntohs(pptpReq->icack.callID);
+ break;
+
+ case PPTP_CALL_CLEAR_REQUEST:
+ /* client requests hangup of call */
+ if (info->sstate != PPTP_SESSION_CONFIRMED) {
+ DEBUGP("CLEAR_CALL but no session\n");
+ break;
+ }
+ /* FUTURE: iterate over all calls and check if
+ * call ID is valid. We don't do this without newnat,
+ * because we only know about last call */
+ info->cstate = PPTP_CALL_CLEAR_REQ;
+ break;
+ case PPTP_SET_LINK_INFO:
+ break;
+ case PPTP_ECHO_REQUEST:
+ case PPTP_ECHO_REPLY:
+ /* I don't have to explain these ;) */
+ break;
+ default:
+ DEBUGP("invalid %s (TY=%d)\n", (msg <= PPTP_MSG_MAX)?
+ pptp_msg_name[msg]:pptp_msg_name[0], msg);
+ /* unknown: no need to create GRE masq table entry */
+ break;
+ }
+
+ if (ip_nat_pptp_hook_outbound)
+ return ip_nat_pptp_hook_outbound(pskb, ct, ctinfo, ctlh,
+ pptpReq);
+
+ return NF_ACCEPT;
+}
+
+
+/* track caller id inside control connection, call expect_related */
+static int
+conntrack_pptp_help(struct sk_buff **pskb,
+ struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
+
+{
+ struct pptp_pkt_hdr _pptph, *pptph;
+ struct tcphdr _tcph, *tcph;
+ u_int32_t tcplen = (*pskb)->len - (*pskb)->nh.iph->ihl * 4;
+ u_int32_t datalen;
+ int dir = CTINFO2DIR(ctinfo);
+ struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
+ unsigned int nexthdr_off;
+
+ int oldsstate, oldcstate;
+ int ret;
+
+ /* don't do any tracking before tcp handshake complete */
+ if (ctinfo != IP_CT_ESTABLISHED
+ && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
+ DEBUGP("ctinfo = %u, skipping\n", ctinfo);
+ return NF_ACCEPT;
+ }
+
+ nexthdr_off = (*pskb)->nh.iph->ihl*4;
+ tcph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_tcph), &_tcph);
+ BUG_ON(!tcph);
+ nexthdr_off += tcph->doff * 4;
+ datalen = tcplen - tcph->doff * 4;
+
+ if (tcph->fin || tcph->rst) {
+ DEBUGP("RST/FIN received, timeouting GRE\n");
+ /* can't do this after real newnat */
+ info->cstate = PPTP_CALL_NONE;
+
+ /* untrack this call id, unexpect GRE packets */
+ pptp_destroy_siblings(ct);
+ }
+
+ pptph = skb_header_pointer(*pskb, nexthdr_off, sizeof(_pptph), &_pptph);
+ if (!pptph) {
+ DEBUGP("no full PPTP header, can't track\n");
+ return NF_ACCEPT;
+ }
+ nexthdr_off += sizeof(_pptph);
+ datalen -= sizeof(_pptph);
+
+ /* if it's not a control message we can't do anything with it */
+ if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
+ ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
+ DEBUGP("not a control packet\n");
+ return NF_ACCEPT;
+ }
+
+ oldsstate = info->sstate;
+ oldcstate = info->cstate;
+
+ spin_lock_bh(&ip_pptp_lock);
+
+ /* FIXME: We just blindly assume that the control connection is always
+ * established from PNS->PAC. However, RFC makes no guarantee */
+ if (dir == IP_CT_DIR_ORIGINAL)
+ /* client -> server (PNS -> PAC) */
+ ret = pptp_outbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
+ ctinfo);
+ else
+ /* server -> client (PAC -> PNS) */
+ ret = pptp_inbound_pkt(pskb, tcph, nexthdr_off, datalen, ct,
+ ctinfo);
+ DEBUGP("sstate: %d->%d, cstate: %d->%d\n",
+ oldsstate, info->sstate, oldcstate, info->cstate);
+ spin_unlock_bh(&ip_pptp_lock);
+
+ return ret;
+}
+
+/* control protocol helper */
+static struct ip_conntrack_helper pptp = {
+ .list = { NULL, NULL },
+ .name = "pptp",
+ .me = THIS_MODULE,
+ .max_expected = 2,
+ .timeout = 5 * 60,
+ .tuple = { .src = { .ip = 0,
+ .u = { .tcp = { .port =
+ __constant_htons(PPTP_CONTROL_PORT) } }
+ },
+ .dst = { .ip = 0,
+ .u = { .all = 0 },
+ .protonum = IPPROTO_TCP
+ }
+ },
+ .mask = { .src = { .ip = 0,
+ .u = { .tcp = { .port = __constant_htons(0xffff) } }
+ },
+ .dst = { .ip = 0,
+ .u = { .all = 0 },
+ .protonum = 0xff
+ }
+ },
+ .help = conntrack_pptp_help
+};
+
+extern void ip_ct_proto_gre_fini(void);
+extern int __init ip_ct_proto_gre_init(void);
+
+/* ip_conntrack_pptp initialization */
+static int __init ip_conntrack_helper_pptp_init(void)
+{
+ int retcode;
+
+ retcode = ip_ct_proto_gre_init();
+ if (retcode < 0)
+ return retcode;
+
+ DEBUGP(" registering helper\n");
+ if ((retcode = ip_conntrack_helper_register(&pptp))) {
+ printk(KERN_ERR "Unable to register conntrack application "
+ "helper for pptp: %d\n", retcode);
+ ip_ct_proto_gre_fini();
+ return retcode;
+ }
+
+ printk("ip_conntrack_pptp version %s loaded\n", IP_CT_PPTP_VERSION);
+ return 0;
+}
+
+static void __exit ip_conntrack_helper_pptp_fini(void)
+{
+ ip_conntrack_helper_unregister(&pptp);
+ ip_ct_proto_gre_fini();
+ printk("ip_conntrack_pptp version %s unloaded\n", IP_CT_PPTP_VERSION);
+}
+
+module_init(ip_conntrack_helper_pptp_init);
+module_exit(ip_conntrack_helper_pptp_fini);
+
+EXPORT_SYMBOL(ip_nat_pptp_hook_outbound);
+EXPORT_SYMBOL(ip_nat_pptp_hook_inbound);
+EXPORT_SYMBOL(ip_nat_pptp_hook_exp_gre);
+EXPORT_SYMBOL(ip_nat_pptp_hook_expectfn);
git://git.onelab.eu / linux-2.6.git / blobdiff