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+/*
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+ * ip_conntrack_pptp.c - Version 3.0
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+ *
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+ * Connection tracking 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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+ * Limitations:
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+ * - We blindly assume that control connections are always
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+ * established in PNS->PAC direction. This is a violation
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+ * of RFFC2673
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+ * - We can only support one single call within each session
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+ *
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+ * TODO:
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+ * - testing of incoming PPTP calls
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+ *
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+ * Changes:
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+ * 2002-02-05 - Version 1.3
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+ * - Call ip_conntrack_unexpect_related() from
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+ * pptp_destroy_siblings() to destroy expectations in case
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+ * CALL_DISCONNECT_NOTIFY or tcp fin packet was seen
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+ * (Philip Craig <philipc@snapgear.com>)
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+ * - Add Version information at module loadtime
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+ * 2002-02-10 - Version 1.6
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+ * - move to C99 style initializers
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+ * - remove second expectation if first arrives
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+ * 2004-10-22 - Version 2.0
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+ * - merge Mandrake's 2.6.x port with recent 2.6.x API changes
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+ * - fix lots of linear skb assumptions from Mandrake's port
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+ * 2005-06-10 - Version 2.1
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+ * - use ip_conntrack_expect_free() instead of kfree() on the
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+ * expect's (which are from the slab for quite some time)
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+ * 2005-06-10 - Version 3.0
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+ * - port helper to post-2.6.11 API changes,
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+ * funded by Oxcoda NetBox Blue (http://www.netboxblue.com/)
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+ * 2005-07-30 - Version 3.1
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+ * - port helper to 2.6.13 API changes
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+ *
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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/netfilter.h>
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+#include <linux/ip.h>
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+#include <net/checksum.h>
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+#include <net/tcp.h>
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+
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+#include <linux/netfilter_ipv4/ip_conntrack.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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+
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+#define IP_CT_PPTP_VERSION "3.1"
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+
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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 connection tracking helper module for PPTP");
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+
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+static DEFINE_SPINLOCK(ip_pptp_lock);
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+
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+int
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+(*ip_nat_pptp_hook_outbound)(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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+int
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+(*ip_nat_pptp_hook_inbound)(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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+int
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+(*ip_nat_pptp_hook_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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+void
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+(*ip_nat_pptp_hook_expectfn)(struct ip_conntrack *ct,
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+ struct ip_conntrack_expect *exp);
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+
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+#if 0
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+/* PptpControlMessageType names */
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+const char *pptp_msg_name[] = {
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+ "UNKNOWN_MESSAGE",
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+ "START_SESSION_REQUEST",
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+ "START_SESSION_REPLY",
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+ "STOP_SESSION_REQUEST",
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+ "STOP_SESSION_REPLY",
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+ "ECHO_REQUEST",
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+ "ECHO_REPLY",
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+ "OUT_CALL_REQUEST",
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+ "OUT_CALL_REPLY",
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+ "IN_CALL_REQUEST",
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+ "IN_CALL_REPLY",
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+ "IN_CALL_CONNECT",
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+ "CALL_CLEAR_REQUEST",
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+ "CALL_DISCONNECT_NOTIFY",
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+ "WAN_ERROR_NOTIFY",
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+ "SET_LINK_INFO"
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+};
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+EXPORT_SYMBOL(pptp_msg_name);
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+#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
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+#else
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+#define DEBUGP(format, args...)
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+#endif
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+
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+#define SECS *HZ
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+#define MINS * 60 SECS
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+#define HOURS * 60 MINS
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+
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+#define PPTP_GRE_TIMEOUT (10 MINS)
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+#define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
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+
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+static void pptp_expectfn(struct ip_conntrack *ct,
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+ struct ip_conntrack_expect *exp)
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+{
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+ DEBUGP("increasing timeouts\n");
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+
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+ /* increase timeout of GRE data channel conntrack entry */
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+ ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
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+ ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
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+
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+ /* Can you see how rusty this code is, compared with the pre-2.6.11
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+ * one? That's what happened to my shiny newnat of 2002 ;( -HW */
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+
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+ if (!ip_nat_pptp_hook_expectfn) {
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+ struct ip_conntrack_tuple inv_t;
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+ struct ip_conntrack_expect *exp_other;
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+
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+ /* obviously this tuple inversion only works until you do NAT */
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+ invert_tuplepr(&inv_t, &exp->tuple);
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+ DEBUGP("trying to unexpect other dir: ");
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+ DUMP_TUPLE(&inv_t);
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+
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+ exp_other = ip_conntrack_expect_find(&inv_t);
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+ if (exp_other) {
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+ /* delete other expectation. */
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+ DEBUGP("found\n");
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+ ip_conntrack_unexpect_related(exp_other);
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+ ip_conntrack_expect_put(exp_other);
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+ } else {
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+ DEBUGP("not found\n");
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+ }
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+ } else {
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+ /* we need more than simple inversion */
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+ ip_nat_pptp_hook_expectfn(ct, exp);
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+ }
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+}
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+
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+static int destroy_sibling_or_exp(const struct ip_conntrack_tuple *t)
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+{
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+ struct ip_conntrack_tuple_hash *h;
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+ struct ip_conntrack_expect *exp;
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+
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+ DEBUGP("trying to timeout ct or exp for tuple ");
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+ DUMP_TUPLE(t);
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+
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+ h = ip_conntrack_find_get(t, NULL);
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+ if (h) {
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+ struct ip_conntrack *sibling = tuplehash_to_ctrack(h);
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+ DEBUGP("setting timeout of conntrack %p to 0\n", sibling);
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+ sibling->proto.gre.timeout = 0;
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+ sibling->proto.gre.stream_timeout = 0;
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+ /* refresh_acct will not modify counters if skb == NULL */
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+ if (del_timer(&sibling->timeout))
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+ sibling->timeout.function((unsigned long)sibling);
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+ ip_conntrack_put(sibling);
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+ return 1;
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+ } else {
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+ exp = ip_conntrack_expect_find(t);
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+ if (exp) {
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+ DEBUGP("unexpect_related of expect %p\n", exp);
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+ ip_conntrack_unexpect_related(exp);
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+ ip_conntrack_expect_put(exp);
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+ return 1;
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+ }
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+ }
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+
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+ return 0;
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+}
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+
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+
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+/* timeout GRE data connections */
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+static void pptp_destroy_siblings(struct ip_conntrack *ct)
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+{
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+ struct ip_conntrack_tuple t;
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+
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+ /* Since ct->sibling_list has literally rusted away in 2.6.11,
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+ * we now need another way to find out about our sibling
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+ * contrack and expects... -HW */
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+
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+ /* try original (pns->pac) tuple */
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+ memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
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+ t.dst.protonum = IPPROTO_GRE;
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+ t.src.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id);
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+ t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id);
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+
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+ if (!destroy_sibling_or_exp(&t))
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+ DEBUGP("failed to timeout original pns->pac ct/exp\n");
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+
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+ /* try reply (pac->pns) tuple */
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+ memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
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+ t.dst.protonum = IPPROTO_GRE;
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+ t.src.u.gre.key = htons(ct->help.ct_pptp_info.pac_call_id);
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+ t.dst.u.gre.key = htons(ct->help.ct_pptp_info.pns_call_id);
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+
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+ if (!destroy_sibling_or_exp(&t))
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+ DEBUGP("failed to timeout reply pac->pns ct/exp\n");
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+}
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+
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+/* expect GRE connections (PNS->PAC and PAC->PNS direction) */
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+static inline int
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+exp_gre(struct ip_conntrack *master,
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+ u_int32_t seq,
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+ u_int16_t callid,
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+ u_int16_t peer_callid)
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+{
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+ struct ip_conntrack_tuple inv_tuple;
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+ struct ip_conntrack_tuple exp_tuples[] = {
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+ /* tuple in original direction, PNS->PAC */
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+ { .src = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip,
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+ .u = { .gre = { .key = peer_callid } }
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+ },
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+ .dst = { .ip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip,
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+ .u = { .gre = { .key = callid } },
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+ .protonum = IPPROTO_GRE
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+ },
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+ },
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+ /* tuple in reply direction, PAC->PNS */
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+ { .src = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip,
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+ .u = { .gre = { .key = callid } }
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+ },
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+ .dst = { .ip = master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip,
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+ .u = { .gre = { .key = peer_callid } },
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+ .protonum = IPPROTO_GRE
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+ },
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+ }
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+ };
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+ struct ip_conntrack_expect *exp_orig, *exp_reply;
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+ int ret = 1;
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+
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+ exp_orig = ip_conntrack_expect_alloc(master);
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+ if (exp_orig == NULL)
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+ goto out;
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+
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+ exp_reply = ip_conntrack_expect_alloc(master);
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+ if (exp_reply == NULL)
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+ goto out_put_orig;
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+
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+ memcpy(&exp_orig->tuple, &exp_tuples[0], sizeof(exp_orig->tuple));
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+
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+ exp_orig->mask.src.ip = 0xffffffff;
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+ exp_orig->mask.src.u.all = 0;
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+ exp_orig->mask.dst.u.all = 0;
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+ exp_orig->mask.dst.u.gre.key = 0xffff;
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+ exp_orig->mask.dst.ip = 0xffffffff;
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+ exp_orig->mask.dst.protonum = 0xff;
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+
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+ exp_orig->master = master;
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+ exp_orig->expectfn = pptp_expectfn;
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+ exp_orig->flags = 0;
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+
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+ exp_orig->dir = IP_CT_DIR_ORIGINAL;
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+
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+ /* both expectations are identical apart from tuple */
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+ memcpy(exp_reply, exp_orig, sizeof(*exp_reply));
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+ memcpy(&exp_reply->tuple, &exp_tuples[1], sizeof(exp_reply->tuple));
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+
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+ exp_reply->dir = !exp_orig->dir;
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+
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+ if (ip_nat_pptp_hook_exp_gre)
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+ ret = ip_nat_pptp_hook_exp_gre(exp_orig, exp_reply);
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+ else {
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+
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+ DEBUGP("calling expect_related PNS->PAC");
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+ DUMP_TUPLE(&exp_orig->tuple);
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+
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+ if (ip_conntrack_expect_related(exp_orig) != 0) {
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+ DEBUGP("cannot expect_related()\n");
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+ goto out_put_both;
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+ }
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+
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+ DEBUGP("calling expect_related PAC->PNS");
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+ DUMP_TUPLE(&exp_reply->tuple);
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+
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+ if (ip_conntrack_expect_related(exp_reply) != 0) {
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+ DEBUGP("cannot expect_related()\n");
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+ goto out_unexpect_orig;
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+ }
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+
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+ /* Add GRE keymap entries */
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+ if (ip_ct_gre_keymap_add(master, &exp_reply->tuple, 0) != 0) {
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+ DEBUGP("cannot keymap_add() exp\n");
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+ goto out_unexpect_both;
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+ }
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+
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+ invert_tuplepr(&inv_tuple, &exp_reply->tuple);
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+ if (ip_ct_gre_keymap_add(master, &inv_tuple, 1) != 0) {
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+ ip_ct_gre_keymap_destroy(master);
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+ DEBUGP("cannot keymap_add() exp_inv\n");
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+ goto out_unexpect_both;
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+ }
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+ ret = 0;
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+ }
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+
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+out_put_both:
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+ ip_conntrack_expect_put(exp_reply);
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+out_put_orig:
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+ ip_conntrack_expect_put(exp_orig);
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+out:
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+ return ret;
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+
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+out_unexpect_both:
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+ ip_conntrack_unexpect_related(exp_reply);
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+out_unexpect_orig:
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+ ip_conntrack_unexpect_related(exp_orig);
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+ goto out_put_both;
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+}
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+
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+static inline int
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+pptp_inbound_pkt(struct sk_buff **pskb,
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+ struct tcphdr *tcph,
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+ unsigned int nexthdr_off,
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+ unsigned int datalen,
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+ struct ip_conntrack *ct,
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+ enum ip_conntrack_info ctinfo)
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+{
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+ struct PptpControlHeader _ctlh, *ctlh;
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+ unsigned int reqlen;
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+ union pptp_ctrl_union _pptpReq, *pptpReq;
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+ struct ip_ct_pptp_master *info = &ct->help.ct_pptp_info;
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+ u_int16_t msg, *cid, *pcid;
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+ u_int32_t seq;
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+
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+ ctlh = skb_header_pointer(*pskb, nexthdr_off, sizeof(_ctlh), &_ctlh);
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+ if (!ctlh) {
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+ DEBUGP("error during skb_header_pointer\n");
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+ return NF_ACCEPT;
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+ }
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+ nexthdr_off += sizeof(_ctlh);
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+ datalen -= sizeof(_ctlh);
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+
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+ reqlen = datalen;
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+ if (reqlen > sizeof(*pptpReq))
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+ reqlen = sizeof(*pptpReq);
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+ pptpReq = skb_header_pointer(*pskb, nexthdr_off, reqlen, &_pptpReq);
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+ if (!pptpReq) {
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+ DEBUGP("error during skb_header_pointer\n");
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+ return NF_ACCEPT;
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+ }
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+
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+ msg = ntohs(ctlh->messageType);
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+ DEBUGP("inbound control message %s\n", pptp_msg_name[msg]);
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+
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+ switch (msg) {
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+ case PPTP_START_SESSION_REPLY:
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+ if (reqlen < sizeof(_pptpReq.srep)) {
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+ DEBUGP("%s: short packet\n", pptp_msg_name[msg]);
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+ break;
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+ }
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+
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+ /* server confirms new control session */
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+ if (info->sstate < PPTP_SESSION_REQUESTED) {
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+ DEBUGP("%s without START_SESS_REQUEST\n",
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+ pptp_msg_name[msg]);
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+ break;
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+ }
|
|
|
+ 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->sstate != PPTP_CALL_IN_REP
|
|
|
+ && info->sstate != 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(*cid));
|
|
|
+ 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, *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 = 0xffff } }
|
|
|
+ },
|
|
|
+ .dst = { .ip = 0,
|
|
|
+ .u = { .all = 0 },
|
|
|
+ .protonum = 0xff
|
|
|
+ }
|
|
|
+ },
|
|
|
+ .help = conntrack_pptp_help
|
|
|
+};
|
|
|
+
|
|
|
+extern void __exit ip_ct_proto_gre_fini(void);
|
|
|
+extern int __init ip_ct_proto_gre_init(void);
|
|
|
+
|
|
|
+/* ip_conntrack_pptp initialization */
|
|
|
+static int __init 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 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(init);
|
|
|
+module_exit(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);
|