diff options
Diffstat (limited to 'net/netfilter/nf_conntrack_pptp.c')
| -rw-r--r-- | net/netfilter/nf_conntrack_pptp.c | 613 |
1 files changed, 613 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_pptp.c b/net/netfilter/nf_conntrack_pptp.c new file mode 100644 index 000000000..4c679638d --- /dev/null +++ b/net/netfilter/nf_conntrack_pptp.c @@ -0,0 +1,613 @@ +// 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); + +const struct nf_nat_pptp_hook __rcu *nf_nat_pptp_hook; +EXPORT_SYMBOL_GPL(nf_nat_pptp_hook); + +#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) +{ + const struct nf_nat_pptp_hook *hook; + struct net *net = nf_ct_net(ct); + 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 */ + + hook = rcu_dereference(nf_nat_pptp_hook); + if (hook && ct->master->status & IPS_NAT_MASK) + hook->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; + const struct nf_nat_pptp_hook *hook; + enum ip_conntrack_dir dir; + int ret = 1; + + 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; + + hook = rcu_dereference(nf_nat_pptp_hook); + if (hook && ct->status & IPS_NAT_MASK) + hook->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); + const struct nf_nat_pptp_hook *hook; + u_int16_t msg; + __be16 cid = 0, pcid = 0; + + 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; + } + + hook = rcu_dereference(nf_nat_pptp_hook); + if (hook && ct->status & IPS_NAT_MASK) + return hook->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); + const struct nf_nat_pptp_hook *hook; + u_int16_t msg; + __be16 cid = 0, pcid = 0; + + 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; + } + + hook = rcu_dereference(nf_nat_pptp_hook); + if (hook && ct->status & IPS_NAT_MASK) + return hook->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; + 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; + +#if IS_ENABLED(CONFIG_NF_NAT) + if (!nf_ct_is_confirmed(ct) && (ct->status & IPS_NAT_MASK)) { + struct nf_conn_nat *nat = nf_ct_ext_find(ct, NF_CT_EXT_NAT); + + if (!nat && !nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC)) + return NF_DROP; + } +#endif + /* 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); + if (!tcph) + return NF_ACCEPT; + + 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, + .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) +{ + NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master)); + + 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); |