From f09943fefe6b702e40893d35b4f10fd1064037fe Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sat, 2 Dec 2006 22:09:41 -0800 Subject: [NETFILTER]: nf_conntrack/nf_nat: add PPTP helper port Add nf_conntrack port of the PPtP conntrack/NAT helper. Since there seems to be no IPv6-capable PPtP implementation the helper only support IPv4. Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/ipv4/netfilter/Kconfig | 10 ++ net/ipv4/netfilter/Makefile | 4 + net/ipv4/netfilter/nf_nat_pptp.c | 315 ++++++++++++++++++++++++++++++++++ net/ipv4/netfilter/nf_nat_proto_gre.c | 179 +++++++++++++++++++ 4 files changed, 508 insertions(+) create mode 100644 net/ipv4/netfilter/nf_nat_pptp.c create mode 100644 net/ipv4/netfilter/nf_nat_proto_gre.c (limited to 'net/ipv4') diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig index 4555f721dfc..c3327ac024d 100644 --- a/net/ipv4/netfilter/Kconfig +++ b/net/ipv4/netfilter/Kconfig @@ -484,6 +484,10 @@ config IP_NF_NAT_SNMP_BASIC # '&&' (6) # # (6) Returns the result of min(/expr/, /expr/). +config NF_NAT_PROTO_GRE + tristate + depends on NF_NAT && NF_CT_PROTO_GRE + config IP_NF_NAT_FTP tristate depends on IP_NF_IPTABLES && IP_NF_CONNTRACK && IP_NF_NAT @@ -528,6 +532,12 @@ config IP_NF_NAT_PPTP default IP_NF_NAT if IP_NF_PPTP=y default m if IP_NF_PPTP=m +config NF_NAT_PPTP + tristate + depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT + default NF_NAT && NF_CONNTRACK_PPTP + select NF_NAT_PROTO_GRE + config IP_NF_NAT_H323 tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile index 56733c37032..ef33ff2cdda 100644 --- a/net/ipv4/netfilter/Makefile +++ b/net/ipv4/netfilter/Makefile @@ -54,6 +54,10 @@ obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o +obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o + +# NAT protocols (nf_nat) +obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o # generic IP tables obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o diff --git a/net/ipv4/netfilter/nf_nat_pptp.c b/net/ipv4/netfilter/nf_nat_pptp.c new file mode 100644 index 00000000000..0ae45b79a4e --- /dev/null +++ b/net/ipv4/netfilter/nf_nat_pptp.c @@ -0,0 +1,315 @@ +/* + * nf_nat_pptp.c + * + * NAT 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 + * + * Development of this code funded by Astaro AG (http://www.astaro.com/) + * + * TODO: - NAT to a unique tuple, not to TCP source port + * (needs netfilter tuple reservation) + */ + +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +#define NF_NAT_PPTP_VERSION "3.0" + +#define REQ_CID(req, off) (*(__be16 *)((char *)(req) + (off))) + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Harald Welte "); +MODULE_DESCRIPTION("Netfilter NAT helper module for PPTP"); +MODULE_ALIAS("ip_nat_pptp"); + +#if 0 +extern const char *pptp_msg_name[]; +#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \ + __FUNCTION__, ## args) +#else +#define DEBUGP(format, args...) +#endif + +static void pptp_nat_expected(struct nf_conn *ct, + struct nf_conntrack_expect *exp) +{ + struct nf_conn *master = ct->master; + struct nf_conntrack_expect *other_exp; + struct nf_conntrack_tuple t; + struct nf_ct_pptp_master *ct_pptp_info; + struct nf_nat_pptp *nat_pptp_info; + struct ip_nat_range range; + + ct_pptp_info = &nfct_help(master)->help.ct_pptp_info; + nat_pptp_info = &nfct_nat(master)->help.nat_pptp_info; + + /* And here goes the grand finale of corrosion... */ + if (exp->dir == IP_CT_DIR_ORIGINAL) { + DEBUGP("we are PNS->PAC\n"); + /* therefore, build tuple for PAC->PNS */ + t.src.l3num = AF_INET; + t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip; + t.src.u.gre.key = ct_pptp_info->pac_call_id; + t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip; + t.dst.u.gre.key = ct_pptp_info->pns_call_id; + t.dst.protonum = IPPROTO_GRE; + } else { + DEBUGP("we are PAC->PNS\n"); + /* build tuple for PNS->PAC */ + t.src.l3num = AF_INET; + t.src.u3.ip = master->tuplehash[exp->dir].tuple.src.u3.ip; + t.src.u.gre.key = nat_pptp_info->pns_call_id; + t.dst.u3.ip = master->tuplehash[exp->dir].tuple.dst.u3.ip; + t.dst.u.gre.key = nat_pptp_info->pac_call_id; + t.dst.protonum = IPPROTO_GRE; + } + + DEBUGP("trying to unexpect other dir: "); + NF_CT_DUMP_TUPLE(&t); + other_exp = nf_conntrack_expect_find_get(&t); + if (other_exp) { + nf_conntrack_unexpect_related(other_exp); + nf_conntrack_expect_put(other_exp); + DEBUGP("success\n"); + } else { + DEBUGP("not found!\n"); + } + + /* This must be a fresh one. */ + BUG_ON(ct->status & IPS_NAT_DONE_MASK); + + /* Change src to where master sends to */ + range.flags = IP_NAT_RANGE_MAP_IPS; + range.min_ip = range.max_ip + = ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip; + if (exp->dir == IP_CT_DIR_ORIGINAL) { + range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED; + range.min = range.max = exp->saved_proto; + } + /* hook doesn't matter, but it has to do source manip */ + nf_nat_setup_info(ct, &range, NF_IP_POST_ROUTING); + + /* For DST manip, map port here to where it's expected. */ + range.flags = IP_NAT_RANGE_MAP_IPS; + range.min_ip = range.max_ip + = ct->master->tuplehash[!exp->dir].tuple.src.u3.ip; + if (exp->dir == IP_CT_DIR_REPLY) { + range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED; + range.min = range.max = exp->saved_proto; + } + /* hook doesn't matter, but it has to do destination manip */ + nf_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING); +} + +/* outbound packets == from PNS to PAC */ +static int +pptp_outbound_pkt(struct sk_buff **pskb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + struct PptpControlHeader *ctlh, + union pptp_ctrl_union *pptpReq) + +{ + struct nf_ct_pptp_master *ct_pptp_info; + struct nf_nat_pptp *nat_pptp_info; + u_int16_t msg; + __be16 new_callid; + unsigned int cid_off; + + ct_pptp_info = &nfct_help(ct)->help.ct_pptp_info; + nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info; + + new_callid = ct_pptp_info->pns_call_id; + + switch (msg = ntohs(ctlh->messageType)) { + case PPTP_OUT_CALL_REQUEST: + cid_off = offsetof(union pptp_ctrl_union, ocreq.callID); + /* FIXME: ideally we would want to reserve a call ID + * here. current netfilter NAT core is not able to do + * this :( For now we use TCP source port. This breaks + * multiple calls within one control session */ + + /* save original call ID in nat_info */ + nat_pptp_info->pns_call_id = ct_pptp_info->pns_call_id; + + /* don't use tcph->source since we are at a DSTmanip + * hook (e.g. PREROUTING) and pkt is not mangled yet */ + new_callid = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.tcp.port; + + /* save new call ID in ct info */ + ct_pptp_info->pns_call_id = new_callid; + break; + case PPTP_IN_CALL_REPLY: + cid_off = offsetof(union pptp_ctrl_union, icack.callID); + break; + case PPTP_CALL_CLEAR_REQUEST: + cid_off = offsetof(union pptp_ctrl_union, clrreq.callID); + break; + default: + DEBUGP("unknown outbound packet 0x%04x:%s\n", msg, + (msg <= PPTP_MSG_MAX)? + pptp_msg_name[msg]:pptp_msg_name[0]); + /* fall through */ + case PPTP_SET_LINK_INFO: + /* only need to NAT in case PAC is behind NAT box */ + case PPTP_START_SESSION_REQUEST: + case PPTP_START_SESSION_REPLY: + case PPTP_STOP_SESSION_REQUEST: + case PPTP_STOP_SESSION_REPLY: + case PPTP_ECHO_REQUEST: + case PPTP_ECHO_REPLY: + /* no need to alter packet */ + return NF_ACCEPT; + } + + /* only OUT_CALL_REQUEST, IN_CALL_REPLY, CALL_CLEAR_REQUEST pass + * down to here */ + DEBUGP("altering call id from 0x%04x to 0x%04x\n", + ntohs(REQ_CID(pptpReq, cid_off)), ntohs(new_callid)); + + /* mangle packet */ + if (nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, + cid_off + sizeof(struct pptp_pkt_hdr) + + sizeof(struct PptpControlHeader), + sizeof(new_callid), (char *)&new_callid, + sizeof(new_callid)) == 0) + return NF_DROP; + return NF_ACCEPT; +} + +static void +pptp_exp_gre(struct nf_conntrack_expect *expect_orig, + struct nf_conntrack_expect *expect_reply) +{ + struct nf_conn *ct = expect_orig->master; + struct nf_ct_pptp_master *ct_pptp_info; + struct nf_nat_pptp *nat_pptp_info; + + ct_pptp_info = &nfct_help(ct)->help.ct_pptp_info; + nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info; + + /* save original PAC call ID in nat_info */ + nat_pptp_info->pac_call_id = ct_pptp_info->pac_call_id; + + /* alter expectation for PNS->PAC direction */ + expect_orig->saved_proto.gre.key = ct_pptp_info->pns_call_id; + expect_orig->tuple.src.u.gre.key = nat_pptp_info->pns_call_id; + expect_orig->tuple.dst.u.gre.key = ct_pptp_info->pac_call_id; + expect_orig->dir = IP_CT_DIR_ORIGINAL; + + /* alter expectation for PAC->PNS direction */ + expect_reply->saved_proto.gre.key = nat_pptp_info->pns_call_id; + expect_reply->tuple.src.u.gre.key = nat_pptp_info->pac_call_id; + expect_reply->tuple.dst.u.gre.key = ct_pptp_info->pns_call_id; + expect_reply->dir = IP_CT_DIR_REPLY; +} + +/* inbound packets == from PAC to PNS */ +static int +pptp_inbound_pkt(struct sk_buff **pskb, + struct nf_conn *ct, + enum ip_conntrack_info ctinfo, + struct PptpControlHeader *ctlh, + union pptp_ctrl_union *pptpReq) +{ + struct nf_nat_pptp *nat_pptp_info; + u_int16_t msg; + __be16 new_pcid; + unsigned int pcid_off; + + nat_pptp_info = &nfct_nat(ct)->help.nat_pptp_info; + new_pcid = nat_pptp_info->pns_call_id; + + switch (msg = ntohs(ctlh->messageType)) { + case PPTP_OUT_CALL_REPLY: + pcid_off = offsetof(union pptp_ctrl_union, ocack.peersCallID); + break; + case PPTP_IN_CALL_CONNECT: + pcid_off = offsetof(union pptp_ctrl_union, iccon.peersCallID); + break; + case PPTP_IN_CALL_REQUEST: + /* only need to nat in case PAC is behind NAT box */ + return NF_ACCEPT; + case PPTP_WAN_ERROR_NOTIFY: + pcid_off = offsetof(union pptp_ctrl_union, wanerr.peersCallID); + break; + case PPTP_CALL_DISCONNECT_NOTIFY: + pcid_off = offsetof(union pptp_ctrl_union, disc.callID); + break; + case PPTP_SET_LINK_INFO: + pcid_off = offsetof(union pptp_ctrl_union, setlink.peersCallID); + break; + default: + DEBUGP("unknown inbound packet %s\n", (msg <= PPTP_MSG_MAX)? + pptp_msg_name[msg]:pptp_msg_name[0]); + /* fall through */ + case PPTP_START_SESSION_REQUEST: + case PPTP_START_SESSION_REPLY: + case PPTP_STOP_SESSION_REQUEST: + case PPTP_STOP_SESSION_REPLY: + case PPTP_ECHO_REQUEST: + case PPTP_ECHO_REPLY: + /* no need to alter packet */ + return NF_ACCEPT; + } + + /* only OUT_CALL_REPLY, IN_CALL_CONNECT, IN_CALL_REQUEST, + * WAN_ERROR_NOTIFY, CALL_DISCONNECT_NOTIFY pass down here */ + + /* mangle packet */ + DEBUGP("altering peer call id from 0x%04x to 0x%04x\n", + ntohs(REQ_CID(pptpReq, pcid_off)), ntohs(new_pcid)); + + if (nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, + pcid_off + sizeof(struct pptp_pkt_hdr) + + sizeof(struct PptpControlHeader), + sizeof(new_pcid), (char *)&new_pcid, + sizeof(new_pcid)) == 0) + return NF_DROP; + return NF_ACCEPT; +} + +static int __init nf_nat_helper_pptp_init(void) +{ + nf_nat_need_gre(); + + BUG_ON(rcu_dereference(nf_nat_pptp_hook_outbound)); + rcu_assign_pointer(nf_nat_pptp_hook_outbound, pptp_outbound_pkt); + + BUG_ON(rcu_dereference(nf_nat_pptp_hook_inbound)); + rcu_assign_pointer(nf_nat_pptp_hook_inbound, pptp_inbound_pkt); + + BUG_ON(rcu_dereference(nf_nat_pptp_hook_exp_gre)); + rcu_assign_pointer(nf_nat_pptp_hook_exp_gre, pptp_exp_gre); + + BUG_ON(rcu_dereference(nf_nat_pptp_hook_expectfn)); + rcu_assign_pointer(nf_nat_pptp_hook_expectfn, pptp_nat_expected); + return 0; +} + +static void __exit nf_nat_helper_pptp_fini(void) +{ + rcu_assign_pointer(nf_nat_pptp_hook_expectfn, NULL); + rcu_assign_pointer(nf_nat_pptp_hook_exp_gre, NULL); + rcu_assign_pointer(nf_nat_pptp_hook_inbound, NULL); + rcu_assign_pointer(nf_nat_pptp_hook_outbound, NULL); + synchronize_rcu(); +} + +module_init(nf_nat_helper_pptp_init); +module_exit(nf_nat_helper_pptp_fini); diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c new file mode 100644 index 00000000000..d3de579e09d --- /dev/null +++ b/net/ipv4/netfilter/nf_nat_proto_gre.c @@ -0,0 +1,179 @@ +/* + * nf_nat_proto_gre.c + * + * NAT protocol helper module for GRE. + * + * GRE is a generic encapsulation protocol, which is generally not very + * suited for NAT, as it has no protocol-specific part as port numbers. + * + * It has an optional key field, which may help us distinguishing two + * connections between the same two hosts. + * + * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784 + * + * PPTP is built on top of a modified version of GRE, and has a mandatory + * field called "CallID", which serves us for the same purpose as the key + * field in plain GRE. + * + * Documentation about PPTP can be found in RFC 2637 + * + * (C) 2000-2005 by Harald Welte + * + * Development of this code funded by Astaro AG (http://www.astaro.com/) + * + */ + +#include +#include +#include + +#include +#include +#include +#include + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Harald Welte "); +MODULE_DESCRIPTION("Netfilter NAT protocol helper module for GRE"); + +#if 0 +#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, \ + __FUNCTION__, ## args) +#else +#define DEBUGP(x, args...) +#endif + +/* is key in given range between min and max */ +static int +gre_in_range(const struct nf_conntrack_tuple *tuple, + enum nf_nat_manip_type maniptype, + const union nf_conntrack_man_proto *min, + const union nf_conntrack_man_proto *max) +{ + __be16 key; + + if (maniptype == IP_NAT_MANIP_SRC) + key = tuple->src.u.gre.key; + else + key = tuple->dst.u.gre.key; + + return ntohs(key) >= ntohs(min->gre.key) && + ntohs(key) <= ntohs(max->gre.key); +} + +/* generate unique tuple ... */ +static int +gre_unique_tuple(struct nf_conntrack_tuple *tuple, + const struct nf_nat_range *range, + enum nf_nat_manip_type maniptype, + const struct nf_conn *conntrack) +{ + static u_int16_t key; + __be16 *keyptr; + unsigned int min, i, range_size; + + if (maniptype == IP_NAT_MANIP_SRC) + keyptr = &tuple->src.u.gre.key; + else + keyptr = &tuple->dst.u.gre.key; + + if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) { + DEBUGP("%p: NATing GRE PPTP\n", conntrack); + min = 1; + range_size = 0xffff; + } else { + min = ntohs(range->min.gre.key); + range_size = ntohs(range->max.gre.key) - min + 1; + } + + DEBUGP("min = %u, range_size = %u\n", min, range_size); + + for (i = 0; i < range_size; i++, key++) { + *keyptr = htons(min + key % range_size); + if (!nf_nat_used_tuple(tuple, conntrack)) + return 1; + } + + DEBUGP("%p: no NAT mapping\n", conntrack); + return 0; +} + +/* manipulate a GRE packet according to maniptype */ +static int +gre_manip_pkt(struct sk_buff **pskb, unsigned int iphdroff, + const struct nf_conntrack_tuple *tuple, + enum nf_nat_manip_type maniptype) +{ + struct gre_hdr *greh; + struct gre_hdr_pptp *pgreh; + struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); + unsigned int hdroff = iphdroff + iph->ihl * 4; + + /* pgreh includes two optional 32bit fields which are not required + * to be there. That's where the magic '8' comes from */ + if (!skb_make_writable(pskb, hdroff + sizeof(*pgreh) - 8)) + return 0; + + greh = (void *)(*pskb)->data + hdroff; + pgreh = (struct gre_hdr_pptp *)greh; + + /* we only have destination manip of a packet, since 'source key' + * is not present in the packet itself */ + if (maniptype != IP_NAT_MANIP_DST) + return 1; + switch (greh->version) { + case 0: + if (!greh->key) { + DEBUGP("can't nat GRE w/o key\n"); + break; + } + if (greh->csum) { + /* FIXME: Never tested this code... */ + nf_proto_csum_replace4(gre_csum(greh), *pskb, + *(gre_key(greh)), + tuple->dst.u.gre.key, 0); + } + *(gre_key(greh)) = tuple->dst.u.gre.key; + break; + case GRE_VERSION_PPTP: + DEBUGP("call_id -> 0x%04x\n", ntohs(tuple->dst.u.gre.key)); + pgreh->call_id = tuple->dst.u.gre.key; + break; + default: + DEBUGP("can't nat unknown GRE version\n"); + return 0; + } + return 1; +} + +static struct nf_nat_protocol gre __read_mostly = { + .name = "GRE", + .protonum = IPPROTO_GRE, + .manip_pkt = gre_manip_pkt, + .in_range = gre_in_range, + .unique_tuple = gre_unique_tuple, +#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ + defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) + .range_to_nfattr = nf_nat_port_range_to_nfattr, + .nfattr_to_range = nf_nat_port_nfattr_to_range, +#endif +}; + +int __init nf_nat_proto_gre_init(void) +{ + return nf_nat_protocol_register(&gre); +} + +void __exit nf_nat_proto_gre_fini(void) +{ + nf_nat_protocol_unregister(&gre); +} + +module_init(nf_nat_proto_gre_init); +module_exit(nf_nat_proto_gre_fini); + +void nf_nat_need_gre(void) +{ + return; +} +EXPORT_SYMBOL_GPL(nf_nat_need_gre); -- cgit v1.2.3