// SPDX-License-Identifier: GPL-2.0-only
|
/*
|
* Connection tracking support for PPTP (Point to Point Tunneling Protocol).
|
* PPTP is 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/)
|
*
|
* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
|
*
|
* Limitations:
|
* - We blindly assume that control connections are always
|
* established in PNS->PAC direction. This is a violation
|
* of RFC 2637
|
* - We can only support one single call within each session
|
* TODO:
|
* - testing of incoming PPTP calls
|
*/
|
|
#include <linux/module.h>
|
#include <linux/skbuff.h>
|
#include <linux/in.h>
|
#include <linux/tcp.h>
|
|
#include <net/netfilter/nf_conntrack.h>
|
#include <net/netfilter/nf_conntrack_core.h>
|
#include <net/netfilter/nf_conntrack_helper.h>
|
#include <net/netfilter/nf_conntrack_zones.h>
|
#include <linux/netfilter/nf_conntrack_proto_gre.h>
|
#include <linux/netfilter/nf_conntrack_pptp.h>
|
|
#define NF_CT_PPTP_VERSION "3.1"
|
|
MODULE_LICENSE("GPL");
|
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
|
MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
|
MODULE_ALIAS("ip_conntrack_pptp");
|
MODULE_ALIAS_NFCT_HELPER("pptp");
|
|
static DEFINE_SPINLOCK(nf_pptp_lock);
|
|
int
|
(*nf_nat_pptp_hook_outbound)(struct sk_buff *skb,
|
struct nf_conn *ct, enum ip_conntrack_info ctinfo,
|
unsigned int protoff, struct PptpControlHeader *ctlh,
|
union pptp_ctrl_union *pptpReq) __read_mostly;
|
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_outbound);
|
|
int
|
(*nf_nat_pptp_hook_inbound)(struct sk_buff *skb,
|
struct nf_conn *ct, enum ip_conntrack_info ctinfo,
|
unsigned int protoff, struct PptpControlHeader *ctlh,
|
union pptp_ctrl_union *pptpReq) __read_mostly;
|
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_inbound);
|
|
void
|
(*nf_nat_pptp_hook_exp_gre)(struct nf_conntrack_expect *expect_orig,
|
struct nf_conntrack_expect *expect_reply)
|
__read_mostly;
|
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_exp_gre);
|
|
void
|
(*nf_nat_pptp_hook_expectfn)(struct nf_conn *ct,
|
struct nf_conntrack_expect *exp) __read_mostly;
|
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);
|
|
#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
|
/* PptpControlMessageType names */
|
static const char *const pptp_msg_name_array[PPTP_MSG_MAX + 1] = {
|
[0] = "UNKNOWN_MESSAGE",
|
[PPTP_START_SESSION_REQUEST] = "START_SESSION_REQUEST",
|
[PPTP_START_SESSION_REPLY] = "START_SESSION_REPLY",
|
[PPTP_STOP_SESSION_REQUEST] = "STOP_SESSION_REQUEST",
|
[PPTP_STOP_SESSION_REPLY] = "STOP_SESSION_REPLY",
|
[PPTP_ECHO_REQUEST] = "ECHO_REQUEST",
|
[PPTP_ECHO_REPLY] = "ECHO_REPLY",
|
[PPTP_OUT_CALL_REQUEST] = "OUT_CALL_REQUEST",
|
[PPTP_OUT_CALL_REPLY] = "OUT_CALL_REPLY",
|
[PPTP_IN_CALL_REQUEST] = "IN_CALL_REQUEST",
|
[PPTP_IN_CALL_REPLY] = "IN_CALL_REPLY",
|
[PPTP_IN_CALL_CONNECT] = "IN_CALL_CONNECT",
|
[PPTP_CALL_CLEAR_REQUEST] = "CALL_CLEAR_REQUEST",
|
[PPTP_CALL_DISCONNECT_NOTIFY] = "CALL_DISCONNECT_NOTIFY",
|
[PPTP_WAN_ERROR_NOTIFY] = "WAN_ERROR_NOTIFY",
|
[PPTP_SET_LINK_INFO] = "SET_LINK_INFO"
|
};
|
|
const char *pptp_msg_name(u_int16_t msg)
|
{
|
if (msg > PPTP_MSG_MAX)
|
return pptp_msg_name_array[0];
|
|
return pptp_msg_name_array[msg];
|
}
|
EXPORT_SYMBOL(pptp_msg_name);
|
#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 nf_conn *ct,
|
struct nf_conntrack_expect *exp)
|
{
|
struct net *net = nf_ct_net(ct);
|
typeof(nf_nat_pptp_hook_expectfn) nf_nat_pptp_expectfn;
|
pr_debug("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 */
|
|
nf_nat_pptp_expectfn = rcu_dereference(nf_nat_pptp_hook_expectfn);
|
if (nf_nat_pptp_expectfn && ct->master->status & IPS_NAT_MASK)
|
nf_nat_pptp_expectfn(ct, exp);
|
else {
|
struct nf_conntrack_tuple inv_t;
|
struct nf_conntrack_expect *exp_other;
|
|
/* obviously this tuple inversion only works until you do NAT */
|
nf_ct_invert_tuple(&inv_t, &exp->tuple);
|
pr_debug("trying to unexpect other dir: ");
|
nf_ct_dump_tuple(&inv_t);
|
|
exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t);
|
if (exp_other) {
|
/* delete other expectation. */
|
pr_debug("found\n");
|
nf_ct_unexpect_related(exp_other);
|
nf_ct_expect_put(exp_other);
|
} else {
|
pr_debug("not found\n");
|
}
|
}
|
}
|
|
static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct,
|
const struct nf_conntrack_tuple *t)
|
{
|
const struct nf_conntrack_tuple_hash *h;
|
const struct nf_conntrack_zone *zone;
|
struct nf_conntrack_expect *exp;
|
struct nf_conn *sibling;
|
|
pr_debug("trying to timeout ct or exp for tuple ");
|
nf_ct_dump_tuple(t);
|
|
zone = nf_ct_zone(ct);
|
h = nf_conntrack_find_get(net, zone, t);
|
if (h) {
|
sibling = nf_ct_tuplehash_to_ctrack(h);
|
pr_debug("setting timeout of conntrack %p to 0\n", sibling);
|
sibling->proto.gre.timeout = 0;
|
sibling->proto.gre.stream_timeout = 0;
|
nf_ct_kill(sibling);
|
nf_ct_put(sibling);
|
return 1;
|
} else {
|
exp = nf_ct_expect_find_get(net, zone, t);
|
if (exp) {
|
pr_debug("unexpect_related of expect %p\n", exp);
|
nf_ct_unexpect_related(exp);
|
nf_ct_expect_put(exp);
|
return 1;
|
}
|
}
|
return 0;
|
}
|
|
/* timeout GRE data connections */
|
static void pptp_destroy_siblings(struct nf_conn *ct)
|
{
|
struct net *net = nf_ct_net(ct);
|
const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
|
struct nf_conntrack_tuple t;
|
|
nf_ct_gre_keymap_destroy(ct);
|
|
/* 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 = ct_pptp_info->pns_call_id;
|
t.dst.u.gre.key = ct_pptp_info->pac_call_id;
|
if (!destroy_sibling_or_exp(net, ct, &t))
|
pr_debug("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 = ct_pptp_info->pac_call_id;
|
t.dst.u.gre.key = ct_pptp_info->pns_call_id;
|
if (!destroy_sibling_or_exp(net, ct, &t))
|
pr_debug("failed to timeout reply pac->pns ct/exp\n");
|
}
|
|
/* expect GRE connections (PNS->PAC and PAC->PNS direction) */
|
static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
|
{
|
struct nf_conntrack_expect *exp_orig, *exp_reply;
|
enum ip_conntrack_dir dir;
|
int ret = 1;
|
typeof(nf_nat_pptp_hook_exp_gre) nf_nat_pptp_exp_gre;
|
|
exp_orig = nf_ct_expect_alloc(ct);
|
if (exp_orig == NULL)
|
goto out;
|
|
exp_reply = nf_ct_expect_alloc(ct);
|
if (exp_reply == NULL)
|
goto out_put_orig;
|
|
/* original direction, PNS->PAC */
|
dir = IP_CT_DIR_ORIGINAL;
|
nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT,
|
nf_ct_l3num(ct),
|
&ct->tuplehash[dir].tuple.src.u3,
|
&ct->tuplehash[dir].tuple.dst.u3,
|
IPPROTO_GRE, &peer_callid, &callid);
|
exp_orig->expectfn = pptp_expectfn;
|
|
/* reply direction, PAC->PNS */
|
dir = IP_CT_DIR_REPLY;
|
nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT,
|
nf_ct_l3num(ct),
|
&ct->tuplehash[dir].tuple.src.u3,
|
&ct->tuplehash[dir].tuple.dst.u3,
|
IPPROTO_GRE, &callid, &peer_callid);
|
exp_reply->expectfn = pptp_expectfn;
|
|
nf_nat_pptp_exp_gre = rcu_dereference(nf_nat_pptp_hook_exp_gre);
|
if (nf_nat_pptp_exp_gre && ct->status & IPS_NAT_MASK)
|
nf_nat_pptp_exp_gre(exp_orig, exp_reply);
|
if (nf_ct_expect_related(exp_orig, 0) != 0)
|
goto out_put_both;
|
if (nf_ct_expect_related(exp_reply, 0) != 0)
|
goto out_unexpect_orig;
|
|
/* Add GRE keymap entries */
|
if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0)
|
goto out_unexpect_both;
|
if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) {
|
nf_ct_gre_keymap_destroy(ct);
|
goto out_unexpect_both;
|
}
|
ret = 0;
|
|
out_put_both:
|
nf_ct_expect_put(exp_reply);
|
out_put_orig:
|
nf_ct_expect_put(exp_orig);
|
out:
|
return ret;
|
|
out_unexpect_both:
|
nf_ct_unexpect_related(exp_reply);
|
out_unexpect_orig:
|
nf_ct_unexpect_related(exp_orig);
|
goto out_put_both;
|
}
|
|
static int
|
pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff,
|
struct PptpControlHeader *ctlh,
|
union pptp_ctrl_union *pptpReq,
|
unsigned int reqlen,
|
struct nf_conn *ct,
|
enum ip_conntrack_info ctinfo)
|
{
|
struct nf_ct_pptp_master *info = nfct_help_data(ct);
|
u_int16_t msg;
|
__be16 cid = 0, pcid = 0;
|
typeof(nf_nat_pptp_hook_inbound) nf_nat_pptp_inbound;
|
|
msg = ntohs(ctlh->messageType);
|
pr_debug("inbound control message %s\n", pptp_msg_name(msg));
|
|
switch (msg) {
|
case PPTP_START_SESSION_REPLY:
|
/* server confirms new control session */
|
if (info->sstate < PPTP_SESSION_REQUESTED)
|
goto invalid;
|
if (pptpReq->srep.resultCode == PPTP_START_OK)
|
info->sstate = PPTP_SESSION_CONFIRMED;
|
else
|
info->sstate = PPTP_SESSION_ERROR;
|
break;
|
|
case PPTP_STOP_SESSION_REPLY:
|
/* server confirms end of control session */
|
if (info->sstate > PPTP_SESSION_STOPREQ)
|
goto invalid;
|
if (pptpReq->strep.resultCode == PPTP_STOP_OK)
|
info->sstate = PPTP_SESSION_NONE;
|
else
|
info->sstate = PPTP_SESSION_ERROR;
|
break;
|
|
case PPTP_OUT_CALL_REPLY:
|
/* server accepted call, we now expect GRE frames */
|
if (info->sstate != PPTP_SESSION_CONFIRMED)
|
goto invalid;
|
if (info->cstate != PPTP_CALL_OUT_REQ &&
|
info->cstate != PPTP_CALL_OUT_CONF)
|
goto invalid;
|
|
cid = pptpReq->ocack.callID;
|
pcid = pptpReq->ocack.peersCallID;
|
if (info->pns_call_id != pcid)
|
goto invalid;
|
pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name(msg),
|
ntohs(cid), ntohs(pcid));
|
|
if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
|
info->cstate = PPTP_CALL_OUT_CONF;
|
info->pac_call_id = cid;
|
exp_gre(ct, cid, pcid);
|
} else
|
info->cstate = PPTP_CALL_NONE;
|
break;
|
|
case PPTP_IN_CALL_REQUEST:
|
/* server tells us about incoming call request */
|
if (info->sstate != PPTP_SESSION_CONFIRMED)
|
goto invalid;
|
|
cid = pptpReq->icreq.callID;
|
pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
|
info->cstate = PPTP_CALL_IN_REQ;
|
info->pac_call_id = cid;
|
break;
|
|
case PPTP_IN_CALL_CONNECT:
|
/* server tells us about incoming call established */
|
if (info->sstate != PPTP_SESSION_CONFIRMED)
|
goto invalid;
|
if (info->cstate != PPTP_CALL_IN_REP &&
|
info->cstate != PPTP_CALL_IN_CONF)
|
goto invalid;
|
|
pcid = pptpReq->iccon.peersCallID;
|
cid = info->pac_call_id;
|
|
if (info->pns_call_id != pcid)
|
goto invalid;
|
|
pr_debug("%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 */
|
exp_gre(ct, cid, pcid);
|
break;
|
|
case PPTP_CALL_DISCONNECT_NOTIFY:
|
/* server confirms disconnect */
|
cid = pptpReq->disc.callID;
|
pr_debug("%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:
|
case PPTP_SET_LINK_INFO:
|
case PPTP_ECHO_REQUEST:
|
case PPTP_ECHO_REPLY:
|
/* I don't have to explain these ;) */
|
break;
|
|
default:
|
goto invalid;
|
}
|
|
nf_nat_pptp_inbound = rcu_dereference(nf_nat_pptp_hook_inbound);
|
if (nf_nat_pptp_inbound && ct->status & IPS_NAT_MASK)
|
return nf_nat_pptp_inbound(skb, ct, ctinfo,
|
protoff, ctlh, pptpReq);
|
return NF_ACCEPT;
|
|
invalid:
|
pr_debug("invalid %s: type=%d cid=%u pcid=%u "
|
"cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
|
pptp_msg_name(msg),
|
msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
|
ntohs(info->pns_call_id), ntohs(info->pac_call_id));
|
return NF_ACCEPT;
|
}
|
|
static int
|
pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff,
|
struct PptpControlHeader *ctlh,
|
union pptp_ctrl_union *pptpReq,
|
unsigned int reqlen,
|
struct nf_conn *ct,
|
enum ip_conntrack_info ctinfo)
|
{
|
struct nf_ct_pptp_master *info = nfct_help_data(ct);
|
u_int16_t msg;
|
__be16 cid = 0, pcid = 0;
|
typeof(nf_nat_pptp_hook_outbound) nf_nat_pptp_outbound;
|
|
msg = ntohs(ctlh->messageType);
|
pr_debug("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)
|
goto invalid;
|
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:
|
/* client initiating connection to server */
|
if (info->sstate != PPTP_SESSION_CONFIRMED)
|
goto invalid;
|
info->cstate = PPTP_CALL_OUT_REQ;
|
/* track PNS call id */
|
cid = pptpReq->ocreq.callID;
|
pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
|
info->pns_call_id = cid;
|
break;
|
|
case PPTP_IN_CALL_REPLY:
|
/* client answers incoming call */
|
if (info->cstate != PPTP_CALL_IN_REQ &&
|
info->cstate != PPTP_CALL_IN_REP)
|
goto invalid;
|
|
cid = pptpReq->icack.callID;
|
pcid = pptpReq->icack.peersCallID;
|
if (info->pac_call_id != pcid)
|
goto invalid;
|
pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name(msg),
|
ntohs(cid), ntohs(pcid));
|
|
if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
|
/* part two of the three-way handshake */
|
info->cstate = PPTP_CALL_IN_REP;
|
info->pns_call_id = cid;
|
} else
|
info->cstate = PPTP_CALL_NONE;
|
break;
|
|
case PPTP_CALL_CLEAR_REQUEST:
|
/* client requests hangup of call */
|
if (info->sstate != PPTP_SESSION_CONFIRMED)
|
goto invalid;
|
/* 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:
|
case PPTP_ECHO_REQUEST:
|
case PPTP_ECHO_REPLY:
|
/* I don't have to explain these ;) */
|
break;
|
|
default:
|
goto invalid;
|
}
|
|
nf_nat_pptp_outbound = rcu_dereference(nf_nat_pptp_hook_outbound);
|
if (nf_nat_pptp_outbound && ct->status & IPS_NAT_MASK)
|
return nf_nat_pptp_outbound(skb, ct, ctinfo,
|
protoff, ctlh, pptpReq);
|
return NF_ACCEPT;
|
|
invalid:
|
pr_debug("invalid %s: type=%d cid=%u pcid=%u "
|
"cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
|
pptp_msg_name(msg),
|
msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
|
ntohs(info->pns_call_id), ntohs(info->pac_call_id));
|
return NF_ACCEPT;
|
}
|
|
static const unsigned int pptp_msg_size[] = {
|
[PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
|
[PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
|
[PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
|
[PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
|
[PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
|
[PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
|
[PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
|
[PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
|
[PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
|
[PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
|
[PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
|
[PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
|
[PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
|
};
|
|
/* track caller id inside control connection, call expect_related */
|
static int
|
conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
|
struct nf_conn *ct, enum ip_conntrack_info ctinfo)
|
|
{
|
int dir = CTINFO2DIR(ctinfo);
|
const struct nf_ct_pptp_master *info = nfct_help_data(ct);
|
const struct tcphdr *tcph;
|
struct tcphdr _tcph;
|
const struct pptp_pkt_hdr *pptph;
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struct pptp_pkt_hdr _pptph;
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struct PptpControlHeader _ctlh, *ctlh;
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union pptp_ctrl_union _pptpReq, *pptpReq;
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unsigned int tcplen = skb->len - protoff;
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unsigned int datalen, reqlen, nexthdr_off;
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int oldsstate, oldcstate;
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int ret;
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u_int16_t msg;
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#if IS_ENABLED(CONFIG_NF_NAT)
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if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) {
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struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
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if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC))
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return NF_DROP;
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}
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#endif
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/* don't do any tracking before tcp handshake complete */
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if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
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return NF_ACCEPT;
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nexthdr_off = protoff;
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tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph);
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BUG_ON(!tcph);
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nexthdr_off += tcph->doff * 4;
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datalen = tcplen - tcph->doff * 4;
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pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph);
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if (!pptph) {
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pr_debug("no full PPTP header, can't track\n");
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return NF_ACCEPT;
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}
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nexthdr_off += sizeof(_pptph);
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datalen -= sizeof(_pptph);
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/* if it's not a control message we can't do anything with it */
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if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
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ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
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pr_debug("not a control packet\n");
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return NF_ACCEPT;
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}
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ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh);
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if (!ctlh)
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return NF_ACCEPT;
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nexthdr_off += sizeof(_ctlh);
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datalen -= sizeof(_ctlh);
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reqlen = datalen;
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msg = ntohs(ctlh->messageType);
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if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
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return NF_ACCEPT;
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if (reqlen > sizeof(*pptpReq))
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reqlen = sizeof(*pptpReq);
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pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq);
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if (!pptpReq)
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return NF_ACCEPT;
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oldsstate = info->sstate;
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oldcstate = info->cstate;
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spin_lock_bh(&nf_pptp_lock);
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/* FIXME: We just blindly assume that the control connection is always
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* established from PNS->PAC. However, RFC makes no guarantee */
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if (dir == IP_CT_DIR_ORIGINAL)
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/* client -> server (PNS -> PAC) */
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ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
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ctinfo);
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else
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/* server -> client (PAC -> PNS) */
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ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
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ctinfo);
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pr_debug("sstate: %d->%d, cstate: %d->%d\n",
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oldsstate, info->sstate, oldcstate, info->cstate);
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spin_unlock_bh(&nf_pptp_lock);
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return ret;
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}
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static const struct nf_conntrack_expect_policy pptp_exp_policy = {
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.max_expected = 2,
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.timeout = 5 * 60,
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};
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/* control protocol helper */
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static struct nf_conntrack_helper pptp __read_mostly = {
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.name = "pptp",
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.me = THIS_MODULE,
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.tuple.src.l3num = AF_INET,
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.tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT),
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.tuple.dst.protonum = IPPROTO_TCP,
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.help = conntrack_pptp_help,
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.destroy = pptp_destroy_siblings,
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.expect_policy = &pptp_exp_policy,
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};
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static int __init nf_conntrack_pptp_init(void)
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{
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NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master));
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return nf_conntrack_helper_register(&pptp);
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}
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static void __exit nf_conntrack_pptp_fini(void)
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{
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nf_conntrack_helper_unregister(&pptp);
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}
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module_init(nf_conntrack_pptp_init);
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module_exit(nf_conntrack_pptp_fini);
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