| /* |
| * Connection tracking support for PPTP (Point to Point Tunneling Protocol). |
| * PPTP is a a protocol for creating virtual private networks. |
| * It is a specification defined by Microsoft and some vendors |
| * working with Microsoft. PPTP is built on top of a modified |
| * version of the Internet Generic Routing Encapsulation Protocol. |
| * GRE is defined in RFC 1701 and RFC 1702. Documentation of |
| * PPTP can be found in RFC 2637 |
| * |
| * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org> |
| * |
| * Development of this code funded by Astaro AG (http://www.astaro.com/) |
| * |
| * (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 */ |
| const char *const pptp_msg_name[] = { |
| "UNKNOWN_MESSAGE", |
| "START_SESSION_REQUEST", |
| "START_SESSION_REPLY", |
| "STOP_SESSION_REQUEST", |
| "STOP_SESSION_REPLY", |
| "ECHO_REQUEST", |
| "ECHO_REPLY", |
| "OUT_CALL_REQUEST", |
| "OUT_CALL_REPLY", |
| "IN_CALL_REQUEST", |
| "IN_CALL_REPLY", |
| "IN_CALL_CONNECT", |
| "CALL_CLEAR_REQUEST", |
| "CALL_DISCONNECT_NOTIFY", |
| "WAN_ERROR_NOTIFY", |
| "SET_LINK_INFO" |
| }; |
| EXPORT_SYMBOL(pptp_msg_name); |
| #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 */ |
| |
| rcu_read_lock(); |
| 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_tuplepr(&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"); |
| } |
| } |
| rcu_read_unlock(); |
| } |
| |
| 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; |
| if (del_timer(&sibling->timeout)) |
| sibling->timeout.function((unsigned long)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) |
| goto out_put_both; |
| if (nf_ct_expect_related(exp_reply) != 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 inline 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", |
| msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], |
| msg, ntohs(cid), ntohs(pcid), info->cstate, info->sstate, |
| ntohs(info->pns_call_id), ntohs(info->pac_call_id)); |
| return NF_ACCEPT; |
| } |
| |
| static inline 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", |
| msg <= PPTP_MSG_MAX ? pptp_msg_name[msg] : pptp_msg_name[0], |
| 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; |
| struct pptp_pkt_hdr _pptph; |
| struct PptpControlHeader _ctlh, *ctlh; |
| union pptp_ctrl_union _pptpReq, *pptpReq; |
| unsigned int tcplen = skb->len - protoff; |
| unsigned int datalen, reqlen, nexthdr_off; |
| int oldsstate, oldcstate; |
| int ret; |
| u_int16_t msg; |
| |
| /* don't do any tracking before tcp handshake complete */ |
| if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY) |
| return NF_ACCEPT; |
| |
| nexthdr_off = protoff; |
| tcph = skb_header_pointer(skb, nexthdr_off, sizeof(_tcph), &_tcph); |
| BUG_ON(!tcph); |
| nexthdr_off += tcph->doff * 4; |
| datalen = tcplen - tcph->doff * 4; |
| |
| pptph = skb_header_pointer(skb, nexthdr_off, sizeof(_pptph), &_pptph); |
| if (!pptph) { |
| pr_debug("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) { |
| pr_debug("not a control packet\n"); |
| return NF_ACCEPT; |
| } |
| |
| ctlh = skb_header_pointer(skb, nexthdr_off, sizeof(_ctlh), &_ctlh); |
| if (!ctlh) |
| return NF_ACCEPT; |
| nexthdr_off += sizeof(_ctlh); |
| datalen -= sizeof(_ctlh); |
| |
| reqlen = datalen; |
| msg = ntohs(ctlh->messageType); |
| if (msg > 0 && msg <= PPTP_MSG_MAX && reqlen < pptp_msg_size[msg]) |
| return NF_ACCEPT; |
| if (reqlen > sizeof(*pptpReq)) |
| reqlen = sizeof(*pptpReq); |
| |
| pptpReq = skb_header_pointer(skb, nexthdr_off, reqlen, &_pptpReq); |
| if (!pptpReq) |
| return NF_ACCEPT; |
| |
| oldsstate = info->sstate; |
| oldcstate = info->cstate; |
| |
| spin_lock_bh(&nf_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(skb, protoff, ctlh, pptpReq, reqlen, ct, |
| ctinfo); |
| else |
| /* server -> client (PAC -> PNS) */ |
| ret = pptp_inbound_pkt(skb, protoff, ctlh, pptpReq, reqlen, ct, |
| ctinfo); |
| pr_debug("sstate: %d->%d, cstate: %d->%d\n", |
| oldsstate, info->sstate, oldcstate, info->cstate); |
| spin_unlock_bh(&nf_pptp_lock); |
| |
| return ret; |
| } |
| |
| static const struct nf_conntrack_expect_policy pptp_exp_policy = { |
| .max_expected = 2, |
| .timeout = 5 * 60, |
| }; |
| |
| /* control protocol helper */ |
| static struct nf_conntrack_helper pptp __read_mostly = { |
| .name = "pptp", |
| .me = THIS_MODULE, |
| .data_len = sizeof(struct nf_ct_pptp_master), |
| .tuple.src.l3num = AF_INET, |
| .tuple.src.u.tcp.port = cpu_to_be16(PPTP_CONTROL_PORT), |
| .tuple.dst.protonum = IPPROTO_TCP, |
| .help = conntrack_pptp_help, |
| .destroy = pptp_destroy_siblings, |
| .expect_policy = &pptp_exp_policy, |
| }; |
| |
| static int __init nf_conntrack_pptp_init(void) |
| { |
| return nf_conntrack_helper_register(&pptp); |
| } |
| |
| static void __exit nf_conntrack_pptp_fini(void) |
| { |
| nf_conntrack_helper_unregister(&pptp); |
| } |
| |
| module_init(nf_conntrack_pptp_init); |
| module_exit(nf_conntrack_pptp_fini); |