109c434b8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only
2f09943feSPatrick McHardy /*
3f09943feSPatrick McHardy * Connection tracking support for PPTP (Point to Point Tunneling Protocol).
44b7ddc58SRandy Dunlap * PPTP is a protocol for creating virtual private networks.
5f09943feSPatrick McHardy * It is a specification defined by Microsoft and some vendors
6f09943feSPatrick McHardy * working with Microsoft. PPTP is built on top of a modified
7f09943feSPatrick McHardy * version of the Internet Generic Routing Encapsulation Protocol.
8f09943feSPatrick McHardy * GRE is defined in RFC 1701 and RFC 1702. Documentation of
9f09943feSPatrick McHardy * PPTP can be found in RFC 2637
10f09943feSPatrick McHardy *
11f09943feSPatrick McHardy * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
12f09943feSPatrick McHardy *
13f09943feSPatrick McHardy * Development of this code funded by Astaro AG (http://www.astaro.com/)
14f09943feSPatrick McHardy *
15f229f6ceSPatrick McHardy * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
16f229f6ceSPatrick McHardy *
17f09943feSPatrick McHardy * Limitations:
18f09943feSPatrick McHardy * - We blindly assume that control connections are always
19f09943feSPatrick McHardy * established in PNS->PAC direction. This is a violation
2038124328SReese Moore * of RFC 2637
21f09943feSPatrick McHardy * - We can only support one single call within each session
22f09943feSPatrick McHardy * TODO:
23f09943feSPatrick McHardy * - testing of incoming PPTP calls
24f09943feSPatrick McHardy */
25f09943feSPatrick McHardy
26f09943feSPatrick McHardy #include <linux/module.h>
27f09943feSPatrick McHardy #include <linux/skbuff.h>
28f09943feSPatrick McHardy #include <linux/in.h>
29f09943feSPatrick McHardy #include <linux/tcp.h>
30f09943feSPatrick McHardy
31f09943feSPatrick McHardy #include <net/netfilter/nf_conntrack.h>
32f09943feSPatrick McHardy #include <net/netfilter/nf_conntrack_core.h>
33f09943feSPatrick McHardy #include <net/netfilter/nf_conntrack_helper.h>
345d0aa2ccSPatrick McHardy #include <net/netfilter/nf_conntrack_zones.h>
35f09943feSPatrick McHardy #include <linux/netfilter/nf_conntrack_proto_gre.h>
36f09943feSPatrick McHardy #include <linux/netfilter/nf_conntrack_pptp.h>
37f09943feSPatrick McHardy
38f09943feSPatrick McHardy #define NF_CT_PPTP_VERSION "3.1"
39f09943feSPatrick McHardy
40f09943feSPatrick McHardy MODULE_LICENSE("GPL");
41f09943feSPatrick McHardy MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
42f09943feSPatrick McHardy MODULE_DESCRIPTION("Netfilter connection tracking helper module for PPTP");
43f09943feSPatrick McHardy MODULE_ALIAS("ip_conntrack_pptp");
444dc06f96SPablo Neira Ayuso MODULE_ALIAS_NFCT_HELPER("pptp");
45f09943feSPatrick McHardy
46f09943feSPatrick McHardy static DEFINE_SPINLOCK(nf_pptp_lock);
47f09943feSPatrick McHardy
48*6976890eSFlorian Westphal const struct nf_nat_pptp_hook __rcu *nf_nat_pptp_hook;
4920ff3202SFlorian Westphal EXPORT_SYMBOL_GPL(nf_nat_pptp_hook);
50f09943feSPatrick McHardy
51e9d376f0SJason Baron #if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
52f09943feSPatrick McHardy /* PptpControlMessageType names */
534c559f15SPablo Neira Ayuso static const char *const pptp_msg_name_array[PPTP_MSG_MAX + 1] = {
544c559f15SPablo Neira Ayuso [0] = "UNKNOWN_MESSAGE",
554c559f15SPablo Neira Ayuso [PPTP_START_SESSION_REQUEST] = "START_SESSION_REQUEST",
564c559f15SPablo Neira Ayuso [PPTP_START_SESSION_REPLY] = "START_SESSION_REPLY",
574c559f15SPablo Neira Ayuso [PPTP_STOP_SESSION_REQUEST] = "STOP_SESSION_REQUEST",
584c559f15SPablo Neira Ayuso [PPTP_STOP_SESSION_REPLY] = "STOP_SESSION_REPLY",
594c559f15SPablo Neira Ayuso [PPTP_ECHO_REQUEST] = "ECHO_REQUEST",
604c559f15SPablo Neira Ayuso [PPTP_ECHO_REPLY] = "ECHO_REPLY",
614c559f15SPablo Neira Ayuso [PPTP_OUT_CALL_REQUEST] = "OUT_CALL_REQUEST",
624c559f15SPablo Neira Ayuso [PPTP_OUT_CALL_REPLY] = "OUT_CALL_REPLY",
634c559f15SPablo Neira Ayuso [PPTP_IN_CALL_REQUEST] = "IN_CALL_REQUEST",
644c559f15SPablo Neira Ayuso [PPTP_IN_CALL_REPLY] = "IN_CALL_REPLY",
654c559f15SPablo Neira Ayuso [PPTP_IN_CALL_CONNECT] = "IN_CALL_CONNECT",
664c559f15SPablo Neira Ayuso [PPTP_CALL_CLEAR_REQUEST] = "CALL_CLEAR_REQUEST",
674c559f15SPablo Neira Ayuso [PPTP_CALL_DISCONNECT_NOTIFY] = "CALL_DISCONNECT_NOTIFY",
684c559f15SPablo Neira Ayuso [PPTP_WAN_ERROR_NOTIFY] = "WAN_ERROR_NOTIFY",
694c559f15SPablo Neira Ayuso [PPTP_SET_LINK_INFO] = "SET_LINK_INFO"
70f09943feSPatrick McHardy };
714c559f15SPablo Neira Ayuso
pptp_msg_name(u_int16_t msg)724946ea5cSPablo Neira Ayuso const char *pptp_msg_name(u_int16_t msg)
734c559f15SPablo Neira Ayuso {
744c559f15SPablo Neira Ayuso if (msg > PPTP_MSG_MAX)
754c559f15SPablo Neira Ayuso return pptp_msg_name_array[0];
764c559f15SPablo Neira Ayuso
774c559f15SPablo Neira Ayuso return pptp_msg_name_array[msg];
784c559f15SPablo Neira Ayuso }
79f09943feSPatrick McHardy EXPORT_SYMBOL(pptp_msg_name);
80f09943feSPatrick McHardy #endif
81f09943feSPatrick McHardy
82f09943feSPatrick McHardy #define SECS *HZ
83f09943feSPatrick McHardy #define MINS * 60 SECS
84f09943feSPatrick McHardy #define HOURS * 60 MINS
85f09943feSPatrick McHardy
86f09943feSPatrick McHardy #define PPTP_GRE_TIMEOUT (10 MINS)
87f09943feSPatrick McHardy #define PPTP_GRE_STREAM_TIMEOUT (5 HOURS)
88f09943feSPatrick McHardy
pptp_expectfn(struct nf_conn * ct,struct nf_conntrack_expect * exp)89f09943feSPatrick McHardy static void pptp_expectfn(struct nf_conn *ct,
90f09943feSPatrick McHardy struct nf_conntrack_expect *exp)
91f09943feSPatrick McHardy {
9220ff3202SFlorian Westphal const struct nf_nat_pptp_hook *hook;
930e6e75afSAlexey Dobriyan struct net *net = nf_ct_net(ct);
940d53778eSPatrick McHardy pr_debug("increasing timeouts\n");
95f09943feSPatrick McHardy
96f09943feSPatrick McHardy /* increase timeout of GRE data channel conntrack entry */
97f09943feSPatrick McHardy ct->proto.gre.timeout = PPTP_GRE_TIMEOUT;
98f09943feSPatrick McHardy ct->proto.gre.stream_timeout = PPTP_GRE_STREAM_TIMEOUT;
99f09943feSPatrick McHardy
100f09943feSPatrick McHardy /* Can you see how rusty this code is, compared with the pre-2.6.11
101f09943feSPatrick McHardy * one? That's what happened to my shiny newnat of 2002 ;( -HW */
102f09943feSPatrick McHardy
10320ff3202SFlorian Westphal hook = rcu_dereference(nf_nat_pptp_hook);
10420ff3202SFlorian Westphal if (hook && ct->master->status & IPS_NAT_MASK)
10520ff3202SFlorian Westphal hook->expectfn(ct, exp);
106f09943feSPatrick McHardy else {
107f09943feSPatrick McHardy struct nf_conntrack_tuple inv_t;
108f09943feSPatrick McHardy struct nf_conntrack_expect *exp_other;
109f09943feSPatrick McHardy
110f09943feSPatrick McHardy /* obviously this tuple inversion only works until you do NAT */
111303e0c55SFlorian Westphal nf_ct_invert_tuple(&inv_t, &exp->tuple);
1120d53778eSPatrick McHardy pr_debug("trying to unexpect other dir: ");
1133c9fba65SJan Engelhardt nf_ct_dump_tuple(&inv_t);
114f09943feSPatrick McHardy
1155d0aa2ccSPatrick McHardy exp_other = nf_ct_expect_find_get(net, nf_ct_zone(ct), &inv_t);
116f09943feSPatrick McHardy if (exp_other) {
117f09943feSPatrick McHardy /* delete other expectation. */
1180d53778eSPatrick McHardy pr_debug("found\n");
1196823645dSPatrick McHardy nf_ct_unexpect_related(exp_other);
1206823645dSPatrick McHardy nf_ct_expect_put(exp_other);
121f09943feSPatrick McHardy } else {
1220d53778eSPatrick McHardy pr_debug("not found\n");
123f09943feSPatrick McHardy }
124f09943feSPatrick McHardy }
125f09943feSPatrick McHardy }
126f09943feSPatrick McHardy
destroy_sibling_or_exp(struct net * net,struct nf_conn * ct,const struct nf_conntrack_tuple * t)1275d0aa2ccSPatrick McHardy static int destroy_sibling_or_exp(struct net *net, struct nf_conn *ct,
1280e6e75afSAlexey Dobriyan const struct nf_conntrack_tuple *t)
129f09943feSPatrick McHardy {
1309ddd0ed0SJan Engelhardt const struct nf_conntrack_tuple_hash *h;
131308ac914SDaniel Borkmann const struct nf_conntrack_zone *zone;
132f09943feSPatrick McHardy struct nf_conntrack_expect *exp;
133f09943feSPatrick McHardy struct nf_conn *sibling;
134f09943feSPatrick McHardy
1350d53778eSPatrick McHardy pr_debug("trying to timeout ct or exp for tuple ");
1363c9fba65SJan Engelhardt nf_ct_dump_tuple(t);
137f09943feSPatrick McHardy
138308ac914SDaniel Borkmann zone = nf_ct_zone(ct);
1395d0aa2ccSPatrick McHardy h = nf_conntrack_find_get(net, zone, t);
140f09943feSPatrick McHardy if (h) {
141f09943feSPatrick McHardy sibling = nf_ct_tuplehash_to_ctrack(h);
1420d53778eSPatrick McHardy pr_debug("setting timeout of conntrack %p to 0\n", sibling);
143f09943feSPatrick McHardy sibling->proto.gre.timeout = 0;
144f09943feSPatrick McHardy sibling->proto.gre.stream_timeout = 0;
145f330a7fdSFlorian Westphal nf_ct_kill(sibling);
146f09943feSPatrick McHardy nf_ct_put(sibling);
147f09943feSPatrick McHardy return 1;
148f09943feSPatrick McHardy } else {
1495d0aa2ccSPatrick McHardy exp = nf_ct_expect_find_get(net, zone, t);
150f09943feSPatrick McHardy if (exp) {
1510d53778eSPatrick McHardy pr_debug("unexpect_related of expect %p\n", exp);
1526823645dSPatrick McHardy nf_ct_unexpect_related(exp);
1536823645dSPatrick McHardy nf_ct_expect_put(exp);
154f09943feSPatrick McHardy return 1;
155f09943feSPatrick McHardy }
156f09943feSPatrick McHardy }
157f09943feSPatrick McHardy return 0;
158f09943feSPatrick McHardy }
159f09943feSPatrick McHardy
160f09943feSPatrick McHardy /* timeout GRE data connections */
pptp_destroy_siblings(struct nf_conn * ct)161f09943feSPatrick McHardy static void pptp_destroy_siblings(struct nf_conn *ct)
162f09943feSPatrick McHardy {
1630e6e75afSAlexey Dobriyan struct net *net = nf_ct_net(ct);
1641afc5679SPablo Neira Ayuso const struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
165f09943feSPatrick McHardy struct nf_conntrack_tuple t;
166f09943feSPatrick McHardy
167f09943feSPatrick McHardy nf_ct_gre_keymap_destroy(ct);
168f09943feSPatrick McHardy
169f09943feSPatrick McHardy /* try original (pns->pac) tuple */
170f09943feSPatrick McHardy memcpy(&t, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, sizeof(t));
171f09943feSPatrick McHardy t.dst.protonum = IPPROTO_GRE;
1721afc5679SPablo Neira Ayuso t.src.u.gre.key = ct_pptp_info->pns_call_id;
1731afc5679SPablo Neira Ayuso t.dst.u.gre.key = ct_pptp_info->pac_call_id;
1745d0aa2ccSPatrick McHardy if (!destroy_sibling_or_exp(net, ct, &t))
1750d53778eSPatrick McHardy pr_debug("failed to timeout original pns->pac ct/exp\n");
176f09943feSPatrick McHardy
177f09943feSPatrick McHardy /* try reply (pac->pns) tuple */
178f09943feSPatrick McHardy memcpy(&t, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, sizeof(t));
179f09943feSPatrick McHardy t.dst.protonum = IPPROTO_GRE;
1801afc5679SPablo Neira Ayuso t.src.u.gre.key = ct_pptp_info->pac_call_id;
1811afc5679SPablo Neira Ayuso t.dst.u.gre.key = ct_pptp_info->pns_call_id;
1825d0aa2ccSPatrick McHardy if (!destroy_sibling_or_exp(net, ct, &t))
1830d53778eSPatrick McHardy pr_debug("failed to timeout reply pac->pns ct/exp\n");
184f09943feSPatrick McHardy }
185f09943feSPatrick McHardy
186f09943feSPatrick McHardy /* expect GRE connections (PNS->PAC and PAC->PNS direction) */
exp_gre(struct nf_conn * ct,__be16 callid,__be16 peer_callid)187f09943feSPatrick McHardy static int exp_gre(struct nf_conn *ct, __be16 callid, __be16 peer_callid)
188f09943feSPatrick McHardy {
189f09943feSPatrick McHardy struct nf_conntrack_expect *exp_orig, *exp_reply;
19020ff3202SFlorian Westphal const struct nf_nat_pptp_hook *hook;
191f09943feSPatrick McHardy enum ip_conntrack_dir dir;
192f09943feSPatrick McHardy int ret = 1;
193f09943feSPatrick McHardy
1946823645dSPatrick McHardy exp_orig = nf_ct_expect_alloc(ct);
195f09943feSPatrick McHardy if (exp_orig == NULL)
196f09943feSPatrick McHardy goto out;
197f09943feSPatrick McHardy
1986823645dSPatrick McHardy exp_reply = nf_ct_expect_alloc(ct);
199f09943feSPatrick McHardy if (exp_reply == NULL)
200f09943feSPatrick McHardy goto out_put_orig;
201f09943feSPatrick McHardy
202f09943feSPatrick McHardy /* original direction, PNS->PAC */
203f09943feSPatrick McHardy dir = IP_CT_DIR_ORIGINAL;
2046002f266SPatrick McHardy nf_ct_expect_init(exp_orig, NF_CT_EXPECT_CLASS_DEFAULT,
2055e8fbe2aSPatrick McHardy nf_ct_l3num(ct),
206f09943feSPatrick McHardy &ct->tuplehash[dir].tuple.src.u3,
207f09943feSPatrick McHardy &ct->tuplehash[dir].tuple.dst.u3,
208f09943feSPatrick McHardy IPPROTO_GRE, &peer_callid, &callid);
209f09943feSPatrick McHardy exp_orig->expectfn = pptp_expectfn;
210f09943feSPatrick McHardy
211f09943feSPatrick McHardy /* reply direction, PAC->PNS */
212f09943feSPatrick McHardy dir = IP_CT_DIR_REPLY;
2136002f266SPatrick McHardy nf_ct_expect_init(exp_reply, NF_CT_EXPECT_CLASS_DEFAULT,
2145e8fbe2aSPatrick McHardy nf_ct_l3num(ct),
215f09943feSPatrick McHardy &ct->tuplehash[dir].tuple.src.u3,
216f09943feSPatrick McHardy &ct->tuplehash[dir].tuple.dst.u3,
217f09943feSPatrick McHardy IPPROTO_GRE, &callid, &peer_callid);
218f09943feSPatrick McHardy exp_reply->expectfn = pptp_expectfn;
219f09943feSPatrick McHardy
22020ff3202SFlorian Westphal hook = rcu_dereference(nf_nat_pptp_hook);
22120ff3202SFlorian Westphal if (hook && ct->status & IPS_NAT_MASK)
22220ff3202SFlorian Westphal hook->exp_gre(exp_orig, exp_reply);
2233c00fb0bSxiao ruizhu if (nf_ct_expect_related(exp_orig, 0) != 0)
224f09943feSPatrick McHardy goto out_put_both;
2253c00fb0bSxiao ruizhu if (nf_ct_expect_related(exp_reply, 0) != 0)
226f09943feSPatrick McHardy goto out_unexpect_orig;
227f09943feSPatrick McHardy
228f09943feSPatrick McHardy /* Add GRE keymap entries */
229f09943feSPatrick McHardy if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_ORIGINAL, &exp_orig->tuple) != 0)
230f09943feSPatrick McHardy goto out_unexpect_both;
231f09943feSPatrick McHardy if (nf_ct_gre_keymap_add(ct, IP_CT_DIR_REPLY, &exp_reply->tuple) != 0) {
232f09943feSPatrick McHardy nf_ct_gre_keymap_destroy(ct);
233f09943feSPatrick McHardy goto out_unexpect_both;
234f09943feSPatrick McHardy }
235f09943feSPatrick McHardy ret = 0;
236f09943feSPatrick McHardy
237f09943feSPatrick McHardy out_put_both:
2386823645dSPatrick McHardy nf_ct_expect_put(exp_reply);
239f09943feSPatrick McHardy out_put_orig:
2406823645dSPatrick McHardy nf_ct_expect_put(exp_orig);
241f09943feSPatrick McHardy out:
242f09943feSPatrick McHardy return ret;
243f09943feSPatrick McHardy
244f09943feSPatrick McHardy out_unexpect_both:
2456823645dSPatrick McHardy nf_ct_unexpect_related(exp_reply);
246f09943feSPatrick McHardy out_unexpect_orig:
2476823645dSPatrick McHardy nf_ct_unexpect_related(exp_orig);
248f09943feSPatrick McHardy goto out_put_both;
249f09943feSPatrick McHardy }
250f09943feSPatrick McHardy
2512fe7c321SFlorian Westphal 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)252051966c0SPatrick McHardy pptp_inbound_pkt(struct sk_buff *skb, unsigned int protoff,
253f09943feSPatrick McHardy struct PptpControlHeader *ctlh,
254f09943feSPatrick McHardy union pptp_ctrl_union *pptpReq,
255f09943feSPatrick McHardy unsigned int reqlen,
256f09943feSPatrick McHardy struct nf_conn *ct,
257f09943feSPatrick McHardy enum ip_conntrack_info ctinfo)
258f09943feSPatrick McHardy {
2591afc5679SPablo Neira Ayuso struct nf_ct_pptp_master *info = nfct_help_data(ct);
26020ff3202SFlorian Westphal const struct nf_nat_pptp_hook *hook;
261f09943feSPatrick McHardy u_int16_t msg;
262f09943feSPatrick McHardy __be16 cid = 0, pcid = 0;
263f09943feSPatrick McHardy
264f09943feSPatrick McHardy msg = ntohs(ctlh->messageType);
2654c559f15SPablo Neira Ayuso pr_debug("inbound control message %s\n", pptp_msg_name(msg));
266f09943feSPatrick McHardy
267f09943feSPatrick McHardy switch (msg) {
268f09943feSPatrick McHardy case PPTP_START_SESSION_REPLY:
269f09943feSPatrick McHardy /* server confirms new control session */
270f09943feSPatrick McHardy if (info->sstate < PPTP_SESSION_REQUESTED)
271f09943feSPatrick McHardy goto invalid;
272f09943feSPatrick McHardy if (pptpReq->srep.resultCode == PPTP_START_OK)
273f09943feSPatrick McHardy info->sstate = PPTP_SESSION_CONFIRMED;
274f09943feSPatrick McHardy else
275f09943feSPatrick McHardy info->sstate = PPTP_SESSION_ERROR;
276f09943feSPatrick McHardy break;
277f09943feSPatrick McHardy
278f09943feSPatrick McHardy case PPTP_STOP_SESSION_REPLY:
279f09943feSPatrick McHardy /* server confirms end of control session */
280f09943feSPatrick McHardy if (info->sstate > PPTP_SESSION_STOPREQ)
281f09943feSPatrick McHardy goto invalid;
282f09943feSPatrick McHardy if (pptpReq->strep.resultCode == PPTP_STOP_OK)
283f09943feSPatrick McHardy info->sstate = PPTP_SESSION_NONE;
284f09943feSPatrick McHardy else
285f09943feSPatrick McHardy info->sstate = PPTP_SESSION_ERROR;
286f09943feSPatrick McHardy break;
287f09943feSPatrick McHardy
288f09943feSPatrick McHardy case PPTP_OUT_CALL_REPLY:
289f09943feSPatrick McHardy /* server accepted call, we now expect GRE frames */
290f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_CONFIRMED)
291f09943feSPatrick McHardy goto invalid;
292f09943feSPatrick McHardy if (info->cstate != PPTP_CALL_OUT_REQ &&
293f09943feSPatrick McHardy info->cstate != PPTP_CALL_OUT_CONF)
294f09943feSPatrick McHardy goto invalid;
295f09943feSPatrick McHardy
296f09943feSPatrick McHardy cid = pptpReq->ocack.callID;
297f09943feSPatrick McHardy pcid = pptpReq->ocack.peersCallID;
298f09943feSPatrick McHardy if (info->pns_call_id != pcid)
299f09943feSPatrick McHardy goto invalid;
3004c559f15SPablo Neira Ayuso pr_debug("%s, CID=%X, PCID=%X\n", pptp_msg_name(msg),
301f09943feSPatrick McHardy ntohs(cid), ntohs(pcid));
302f09943feSPatrick McHardy
303f09943feSPatrick McHardy if (pptpReq->ocack.resultCode == PPTP_OUTCALL_CONNECT) {
304f09943feSPatrick McHardy info->cstate = PPTP_CALL_OUT_CONF;
305f09943feSPatrick McHardy info->pac_call_id = cid;
306f09943feSPatrick McHardy exp_gre(ct, cid, pcid);
307f09943feSPatrick McHardy } else
308f09943feSPatrick McHardy info->cstate = PPTP_CALL_NONE;
309f09943feSPatrick McHardy break;
310f09943feSPatrick McHardy
311f09943feSPatrick McHardy case PPTP_IN_CALL_REQUEST:
312f09943feSPatrick McHardy /* server tells us about incoming call request */
313f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_CONFIRMED)
314f09943feSPatrick McHardy goto invalid;
315f09943feSPatrick McHardy
316f09943feSPatrick McHardy cid = pptpReq->icreq.callID;
3174c559f15SPablo Neira Ayuso pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
318f09943feSPatrick McHardy info->cstate = PPTP_CALL_IN_REQ;
319f09943feSPatrick McHardy info->pac_call_id = cid;
320f09943feSPatrick McHardy break;
321f09943feSPatrick McHardy
322f09943feSPatrick McHardy case PPTP_IN_CALL_CONNECT:
323f09943feSPatrick McHardy /* server tells us about incoming call established */
324f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_CONFIRMED)
325f09943feSPatrick McHardy goto invalid;
326f09943feSPatrick McHardy if (info->cstate != PPTP_CALL_IN_REP &&
327f09943feSPatrick McHardy info->cstate != PPTP_CALL_IN_CONF)
328f09943feSPatrick McHardy goto invalid;
329f09943feSPatrick McHardy
330f09943feSPatrick McHardy pcid = pptpReq->iccon.peersCallID;
331f09943feSPatrick McHardy cid = info->pac_call_id;
332f09943feSPatrick McHardy
333f09943feSPatrick McHardy if (info->pns_call_id != pcid)
334f09943feSPatrick McHardy goto invalid;
335f09943feSPatrick McHardy
3364c559f15SPablo Neira Ayuso pr_debug("%s, PCID=%X\n", pptp_msg_name(msg), ntohs(pcid));
337f09943feSPatrick McHardy info->cstate = PPTP_CALL_IN_CONF;
338f09943feSPatrick McHardy
339f09943feSPatrick McHardy /* we expect a GRE connection from PAC to PNS */
340f09943feSPatrick McHardy exp_gre(ct, cid, pcid);
341f09943feSPatrick McHardy break;
342f09943feSPatrick McHardy
343f09943feSPatrick McHardy case PPTP_CALL_DISCONNECT_NOTIFY:
344f09943feSPatrick McHardy /* server confirms disconnect */
345f09943feSPatrick McHardy cid = pptpReq->disc.callID;
3464c559f15SPablo Neira Ayuso pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
347f09943feSPatrick McHardy info->cstate = PPTP_CALL_NONE;
348f09943feSPatrick McHardy
349f09943feSPatrick McHardy /* untrack this call id, unexpect GRE packets */
350f09943feSPatrick McHardy pptp_destroy_siblings(ct);
351f09943feSPatrick McHardy break;
352f09943feSPatrick McHardy
353f09943feSPatrick McHardy case PPTP_WAN_ERROR_NOTIFY:
3544c6e4209SSanket Shah case PPTP_SET_LINK_INFO:
355f09943feSPatrick McHardy case PPTP_ECHO_REQUEST:
356f09943feSPatrick McHardy case PPTP_ECHO_REPLY:
357f09943feSPatrick McHardy /* I don't have to explain these ;) */
358f09943feSPatrick McHardy break;
359f09943feSPatrick McHardy
360f09943feSPatrick McHardy default:
361f09943feSPatrick McHardy goto invalid;
362f09943feSPatrick McHardy }
363f09943feSPatrick McHardy
36420ff3202SFlorian Westphal hook = rcu_dereference(nf_nat_pptp_hook);
36520ff3202SFlorian Westphal if (hook && ct->status & IPS_NAT_MASK)
36620ff3202SFlorian Westphal return hook->inbound(skb, ct, ctinfo, protoff, ctlh, pptpReq);
367f09943feSPatrick McHardy return NF_ACCEPT;
368f09943feSPatrick McHardy
369f09943feSPatrick McHardy invalid:
3700d53778eSPatrick McHardy pr_debug("invalid %s: type=%d cid=%u pcid=%u "
371f09943feSPatrick McHardy "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
3724c559f15SPablo Neira Ayuso pptp_msg_name(msg),
373f09943feSPatrick McHardy msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
374f09943feSPatrick McHardy ntohs(info->pns_call_id), ntohs(info->pac_call_id));
375f09943feSPatrick McHardy return NF_ACCEPT;
376f09943feSPatrick McHardy }
377f09943feSPatrick McHardy
3782fe7c321SFlorian Westphal 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)379051966c0SPatrick McHardy pptp_outbound_pkt(struct sk_buff *skb, unsigned int protoff,
380f09943feSPatrick McHardy struct PptpControlHeader *ctlh,
381f09943feSPatrick McHardy union pptp_ctrl_union *pptpReq,
382f09943feSPatrick McHardy unsigned int reqlen,
383f09943feSPatrick McHardy struct nf_conn *ct,
384f09943feSPatrick McHardy enum ip_conntrack_info ctinfo)
385f09943feSPatrick McHardy {
3861afc5679SPablo Neira Ayuso struct nf_ct_pptp_master *info = nfct_help_data(ct);
38720ff3202SFlorian Westphal const struct nf_nat_pptp_hook *hook;
388f09943feSPatrick McHardy u_int16_t msg;
389f09943feSPatrick McHardy __be16 cid = 0, pcid = 0;
390f09943feSPatrick McHardy
391f09943feSPatrick McHardy msg = ntohs(ctlh->messageType);
3924c559f15SPablo Neira Ayuso pr_debug("outbound control message %s\n", pptp_msg_name(msg));
393f09943feSPatrick McHardy
394f09943feSPatrick McHardy switch (msg) {
395f09943feSPatrick McHardy case PPTP_START_SESSION_REQUEST:
396f09943feSPatrick McHardy /* client requests for new control session */
397f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_NONE)
398f09943feSPatrick McHardy goto invalid;
399f09943feSPatrick McHardy info->sstate = PPTP_SESSION_REQUESTED;
400f09943feSPatrick McHardy break;
401f09943feSPatrick McHardy
402f09943feSPatrick McHardy case PPTP_STOP_SESSION_REQUEST:
403f09943feSPatrick McHardy /* client requests end of control session */
404f09943feSPatrick McHardy info->sstate = PPTP_SESSION_STOPREQ;
405f09943feSPatrick McHardy break;
406f09943feSPatrick McHardy
407f09943feSPatrick McHardy case PPTP_OUT_CALL_REQUEST:
408f09943feSPatrick McHardy /* client initiating connection to server */
409f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_CONFIRMED)
410f09943feSPatrick McHardy goto invalid;
411f09943feSPatrick McHardy info->cstate = PPTP_CALL_OUT_REQ;
412f09943feSPatrick McHardy /* track PNS call id */
413f09943feSPatrick McHardy cid = pptpReq->ocreq.callID;
4144c559f15SPablo Neira Ayuso pr_debug("%s, CID=%X\n", pptp_msg_name(msg), ntohs(cid));
415f09943feSPatrick McHardy info->pns_call_id = cid;
416f09943feSPatrick McHardy break;
417f09943feSPatrick McHardy
418f09943feSPatrick McHardy case PPTP_IN_CALL_REPLY:
419f09943feSPatrick McHardy /* client answers incoming call */
420f09943feSPatrick McHardy if (info->cstate != PPTP_CALL_IN_REQ &&
421f09943feSPatrick McHardy info->cstate != PPTP_CALL_IN_REP)
422f09943feSPatrick McHardy goto invalid;
423f09943feSPatrick McHardy
424f09943feSPatrick McHardy cid = pptpReq->icack.callID;
425f09943feSPatrick McHardy pcid = pptpReq->icack.peersCallID;
426f09943feSPatrick McHardy if (info->pac_call_id != pcid)
427f09943feSPatrick McHardy goto invalid;
4284c559f15SPablo Neira Ayuso pr_debug("%s, CID=%X PCID=%X\n", pptp_msg_name(msg),
429f09943feSPatrick McHardy ntohs(cid), ntohs(pcid));
430f09943feSPatrick McHardy
431f09943feSPatrick McHardy if (pptpReq->icack.resultCode == PPTP_INCALL_ACCEPT) {
432f09943feSPatrick McHardy /* part two of the three-way handshake */
433f09943feSPatrick McHardy info->cstate = PPTP_CALL_IN_REP;
434f09943feSPatrick McHardy info->pns_call_id = cid;
435f09943feSPatrick McHardy } else
436f09943feSPatrick McHardy info->cstate = PPTP_CALL_NONE;
437f09943feSPatrick McHardy break;
438f09943feSPatrick McHardy
439f09943feSPatrick McHardy case PPTP_CALL_CLEAR_REQUEST:
440f09943feSPatrick McHardy /* client requests hangup of call */
441f09943feSPatrick McHardy if (info->sstate != PPTP_SESSION_CONFIRMED)
442f09943feSPatrick McHardy goto invalid;
443f09943feSPatrick McHardy /* FUTURE: iterate over all calls and check if
444f09943feSPatrick McHardy * call ID is valid. We don't do this without newnat,
445f09943feSPatrick McHardy * because we only know about last call */
446f09943feSPatrick McHardy info->cstate = PPTP_CALL_CLEAR_REQ;
447f09943feSPatrick McHardy break;
448f09943feSPatrick McHardy
449f09943feSPatrick McHardy case PPTP_SET_LINK_INFO:
450f09943feSPatrick McHardy case PPTP_ECHO_REQUEST:
451f09943feSPatrick McHardy case PPTP_ECHO_REPLY:
452f09943feSPatrick McHardy /* I don't have to explain these ;) */
453f09943feSPatrick McHardy break;
454f09943feSPatrick McHardy
455f09943feSPatrick McHardy default:
456f09943feSPatrick McHardy goto invalid;
457f09943feSPatrick McHardy }
458f09943feSPatrick McHardy
45920ff3202SFlorian Westphal hook = rcu_dereference(nf_nat_pptp_hook);
46020ff3202SFlorian Westphal if (hook && ct->status & IPS_NAT_MASK)
46120ff3202SFlorian Westphal return hook->outbound(skb, ct, ctinfo, protoff, ctlh, pptpReq);
462f09943feSPatrick McHardy return NF_ACCEPT;
463f09943feSPatrick McHardy
464f09943feSPatrick McHardy invalid:
4650d53778eSPatrick McHardy pr_debug("invalid %s: type=%d cid=%u pcid=%u "
466f09943feSPatrick McHardy "cstate=%d sstate=%d pns_cid=%u pac_cid=%u\n",
4674c559f15SPablo Neira Ayuso pptp_msg_name(msg),
468f09943feSPatrick McHardy msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate,
469f09943feSPatrick McHardy ntohs(info->pns_call_id), ntohs(info->pac_call_id));
470f09943feSPatrick McHardy return NF_ACCEPT;
471f09943feSPatrick McHardy }
472f09943feSPatrick McHardy
473f09943feSPatrick McHardy static const unsigned int pptp_msg_size[] = {
474f09943feSPatrick McHardy [PPTP_START_SESSION_REQUEST] = sizeof(struct PptpStartSessionRequest),
475f09943feSPatrick McHardy [PPTP_START_SESSION_REPLY] = sizeof(struct PptpStartSessionReply),
476f09943feSPatrick McHardy [PPTP_STOP_SESSION_REQUEST] = sizeof(struct PptpStopSessionRequest),
477f09943feSPatrick McHardy [PPTP_STOP_SESSION_REPLY] = sizeof(struct PptpStopSessionReply),
478f09943feSPatrick McHardy [PPTP_OUT_CALL_REQUEST] = sizeof(struct PptpOutCallRequest),
479f09943feSPatrick McHardy [PPTP_OUT_CALL_REPLY] = sizeof(struct PptpOutCallReply),
480f09943feSPatrick McHardy [PPTP_IN_CALL_REQUEST] = sizeof(struct PptpInCallRequest),
481f09943feSPatrick McHardy [PPTP_IN_CALL_REPLY] = sizeof(struct PptpInCallReply),
482f09943feSPatrick McHardy [PPTP_IN_CALL_CONNECT] = sizeof(struct PptpInCallConnected),
483f09943feSPatrick McHardy [PPTP_CALL_CLEAR_REQUEST] = sizeof(struct PptpClearCallRequest),
484f09943feSPatrick McHardy [PPTP_CALL_DISCONNECT_NOTIFY] = sizeof(struct PptpCallDisconnectNotify),
485f09943feSPatrick McHardy [PPTP_WAN_ERROR_NOTIFY] = sizeof(struct PptpWanErrorNotify),
486f09943feSPatrick McHardy [PPTP_SET_LINK_INFO] = sizeof(struct PptpSetLinkInfo),
487f09943feSPatrick McHardy };
488f09943feSPatrick McHardy
489f09943feSPatrick McHardy /* track caller id inside control connection, call expect_related */
490f09943feSPatrick McHardy static int
conntrack_pptp_help(struct sk_buff * skb,unsigned int protoff,struct nf_conn * ct,enum ip_conntrack_info ctinfo)4913db05feaSHerbert Xu conntrack_pptp_help(struct sk_buff *skb, unsigned int protoff,
492f09943feSPatrick McHardy struct nf_conn *ct, enum ip_conntrack_info ctinfo)
493f09943feSPatrick McHardy
494f09943feSPatrick McHardy {
495f09943feSPatrick McHardy int dir = CTINFO2DIR(ctinfo);
4961afc5679SPablo Neira Ayuso const struct nf_ct_pptp_master *info = nfct_help_data(ct);
4979ddd0ed0SJan Engelhardt const struct tcphdr *tcph;
4989ddd0ed0SJan Engelhardt struct tcphdr _tcph;
4999ddd0ed0SJan Engelhardt const struct pptp_pkt_hdr *pptph;
5009ddd0ed0SJan Engelhardt struct pptp_pkt_hdr _pptph;
501f09943feSPatrick McHardy struct PptpControlHeader _ctlh, *ctlh;
502f09943feSPatrick McHardy union pptp_ctrl_union _pptpReq, *pptpReq;
5033db05feaSHerbert Xu unsigned int tcplen = skb->len - protoff;
504f09943feSPatrick McHardy unsigned int datalen, reqlen, nexthdr_off;
505f09943feSPatrick McHardy int oldsstate, oldcstate;
506f09943feSPatrick McHardy int ret;
507f09943feSPatrick McHardy u_int16_t msg;
508f09943feSPatrick McHardy
5092fe7c321SFlorian Westphal #if IS_ENABLED(CONFIG_NF_NAT)
5102fe7c321SFlorian Westphal if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) {
5112fe7c321SFlorian Westphal struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT);
5122fe7c321SFlorian Westphal
5132fe7c321SFlorian Westphal if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC))
5142fe7c321SFlorian Westphal return NF_DROP;
5152fe7c321SFlorian Westphal }
5162fe7c321SFlorian Westphal #endif
517f09943feSPatrick McHardy /* don't do any tracking before tcp handshake complete */
518fb048833SEric Dumazet if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
519f09943feSPatrick McHardy return NF_ACCEPT;
520f09943feSPatrick McHardy
521f09943feSPatrick McHardy nexthdr_off = protoff;
5223db05feaSHerbert Xu tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph);
523198ad973SPablo Neira Ayuso if (!tcph)
524198ad973SPablo Neira Ayuso return NF_ACCEPT;
525198ad973SPablo Neira Ayuso
526f09943feSPatrick McHardy nexthdr_off += tcph->doff * 4;
527f09943feSPatrick McHardy datalen = tcplen - tcph->doff * 4;
528f09943feSPatrick McHardy
5293db05feaSHerbert Xu pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph);
530f09943feSPatrick McHardy if (!pptph) {
5310d53778eSPatrick McHardy pr_debug("no full PPTP header, can't track\n");
532f09943feSPatrick McHardy return NF_ACCEPT;
533f09943feSPatrick McHardy }
534f09943feSPatrick McHardy nexthdr_off += sizeof(_pptph);
535f09943feSPatrick McHardy datalen -= sizeof(_pptph);
536f09943feSPatrick McHardy
537f09943feSPatrick McHardy /* if it's not a control message we can't do anything with it */
538f09943feSPatrick McHardy if (ntohs(pptph->packetType) != PPTP_PACKET_CONTROL ||
539f09943feSPatrick McHardy ntohl(pptph->magicCookie) != PPTP_MAGIC_COOKIE) {
5400d53778eSPatrick McHardy pr_debug("not a control packet\n");
541f09943feSPatrick McHardy return NF_ACCEPT;
542f09943feSPatrick McHardy }
543f09943feSPatrick McHardy
5443db05feaSHerbert Xu ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh);
545f09943feSPatrick McHardy if (!ctlh)
546f09943feSPatrick McHardy return NF_ACCEPT;
547f09943feSPatrick McHardy nexthdr_off += sizeof(_ctlh);
548f09943feSPatrick McHardy datalen -= sizeof(_ctlh);
549f09943feSPatrick McHardy
550f09943feSPatrick McHardy reqlen = datalen;
551f09943feSPatrick McHardy msg = ntohs(ctlh->messageType);
552f09943feSPatrick McHardy if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg])
553f09943feSPatrick McHardy return NF_ACCEPT;
554f09943feSPatrick McHardy if (reqlen > sizeof(*pptpReq))
555f09943feSPatrick McHardy reqlen = sizeof(*pptpReq);
556f09943feSPatrick McHardy
5573db05feaSHerbert Xu pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq);
558f09943feSPatrick McHardy if (!pptpReq)
559f09943feSPatrick McHardy return NF_ACCEPT;
560f09943feSPatrick McHardy
561f09943feSPatrick McHardy oldsstate = info->sstate;
562f09943feSPatrick McHardy oldcstate = info->cstate;
563f09943feSPatrick McHardy
564f09943feSPatrick McHardy spin_lock_bh(&nf_pptp_lock);
565f09943feSPatrick McHardy
566f09943feSPatrick McHardy /* FIXME: We just blindly assume that the control connection is always
567f09943feSPatrick McHardy * established from PNS->PAC. However, RFC makes no guarantee */
568f09943feSPatrick McHardy if (dir == IP_CT_DIR_ORIGINAL)
569f09943feSPatrick McHardy /* client -> server (PNS -> PAC) */
570051966c0SPatrick McHardy ret = pptp_outbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
571f09943feSPatrick McHardy ctinfo);
572f09943feSPatrick McHardy else
573f09943feSPatrick McHardy /* server -> client (PAC -> PNS) */
574051966c0SPatrick McHardy ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct,
575f09943feSPatrick McHardy ctinfo);
5760d53778eSPatrick McHardy pr_debug("sstate: %d->%d, cstate: %d->%d\n",
577f09943feSPatrick McHardy oldsstate, info->sstate, oldcstate, info->cstate);
578f09943feSPatrick McHardy spin_unlock_bh(&nf_pptp_lock);
579f09943feSPatrick McHardy
580f09943feSPatrick McHardy return ret;
581f09943feSPatrick McHardy }
582f09943feSPatrick McHardy
5836002f266SPatrick McHardy static const struct nf_conntrack_expect_policy pptp_exp_policy = {
5846002f266SPatrick McHardy .max_expected = 2,
5856002f266SPatrick McHardy .timeout = 5 * 60,
5866002f266SPatrick McHardy };
5876002f266SPatrick McHardy
588f09943feSPatrick McHardy /* control protocol helper */
589f09943feSPatrick McHardy static struct nf_conntrack_helper pptp __read_mostly = {
590f09943feSPatrick McHardy .name = "pptp",
591f09943feSPatrick McHardy .me = THIS_MODULE,
592f09943feSPatrick McHardy .tuple.src.l3num = AF_INET,
59309640e63SHarvey Harrison .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT),
594f09943feSPatrick McHardy .tuple.dst.protonum = IPPROTO_TCP,
595f09943feSPatrick McHardy .help = conntrack_pptp_help,
596f09943feSPatrick McHardy .destroy = pptp_destroy_siblings,
5976002f266SPatrick McHardy .expect_policy = &pptp_exp_policy,
598f09943feSPatrick McHardy };
599f09943feSPatrick McHardy
nf_conntrack_pptp_init(void)600f09943feSPatrick McHardy static int __init nf_conntrack_pptp_init(void)
601f09943feSPatrick McHardy {
602dcf67740SFlorian Westphal NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master));
603dcf67740SFlorian Westphal
6048142b227SAndrey Vagin return nf_conntrack_helper_register(&pptp);
605f09943feSPatrick McHardy }
606f09943feSPatrick McHardy
nf_conntrack_pptp_fini(void)607f09943feSPatrick McHardy static void __exit nf_conntrack_pptp_fini(void)
608f09943feSPatrick McHardy {
609f09943feSPatrick McHardy nf_conntrack_helper_unregister(&pptp);
610f09943feSPatrick McHardy }
611f09943feSPatrick McHardy
612f09943feSPatrick McHardy module_init(nf_conntrack_pptp_init);
613f09943feSPatrick McHardy module_exit(nf_conntrack_pptp_fini);
614