| /* |
| * ip_conntrack_proto_gre.c - Version 3.0 |
| * |
| * Connection tracking 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 <laforge@gnumonks.org> |
| * |
| * Development of this code funded by Astaro AG (http://www.astaro.com/) |
| * |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/timer.h> |
| #include <linux/netfilter.h> |
| #include <linux/ip.h> |
| #include <linux/in.h> |
| #include <linux/list.h> |
| #include <linux/seq_file.h> |
| #include <linux/interrupt.h> |
| |
| static DEFINE_RWLOCK(ip_ct_gre_lock); |
| #define ASSERT_READ_LOCK(x) |
| #define ASSERT_WRITE_LOCK(x) |
| |
| #include <linux/netfilter_ipv4/ip_conntrack_protocol.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_core.h> |
| |
| #include <linux/netfilter_ipv4/ip_conntrack_proto_gre.h> |
| #include <linux/netfilter_ipv4/ip_conntrack_pptp.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); |
| MODULE_DESCRIPTION("netfilter connection tracking protocol helper for GRE"); |
| |
| /* shamelessly stolen from ip_conntrack_proto_udp.c */ |
| #define GRE_TIMEOUT (30*HZ) |
| #define GRE_STREAM_TIMEOUT (180*HZ) |
| |
| #if 0 |
| #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args) |
| #define DUMP_TUPLE_GRE(x) printk("%u.%u.%u.%u:0x%x -> %u.%u.%u.%u:0x%x\n", \ |
| NIPQUAD((x)->src.ip), ntohs((x)->src.u.gre.key), \ |
| NIPQUAD((x)->dst.ip), ntohs((x)->dst.u.gre.key)) |
| #else |
| #define DEBUGP(x, args...) |
| #define DUMP_TUPLE_GRE(x) |
| #endif |
| |
| /* GRE KEYMAP HANDLING FUNCTIONS */ |
| static LIST_HEAD(gre_keymap_list); |
| |
| static inline int gre_key_cmpfn(const struct ip_ct_gre_keymap *km, |
| const struct ip_conntrack_tuple *t) |
| { |
| return ((km->tuple.src.ip == t->src.ip) && |
| (km->tuple.dst.ip == t->dst.ip) && |
| (km->tuple.dst.protonum == t->dst.protonum) && |
| (km->tuple.dst.u.all == t->dst.u.all)); |
| } |
| |
| /* look up the source key for a given tuple */ |
| static __be16 gre_keymap_lookup(struct ip_conntrack_tuple *t) |
| { |
| struct ip_ct_gre_keymap *km; |
| __be16 key = 0; |
| |
| read_lock_bh(&ip_ct_gre_lock); |
| list_for_each_entry(km, &gre_keymap_list, list) { |
| if (gre_key_cmpfn(km, t)) { |
| key = km->tuple.src.u.gre.key; |
| break; |
| } |
| } |
| read_unlock_bh(&ip_ct_gre_lock); |
| |
| DEBUGP("lookup src key 0x%x up key for ", key); |
| DUMP_TUPLE_GRE(t); |
| |
| return key; |
| } |
| |
| /* add a single keymap entry, associate with specified master ct */ |
| int |
| ip_ct_gre_keymap_add(struct ip_conntrack *ct, |
| struct ip_conntrack_tuple *t, int reply) |
| { |
| struct ip_ct_gre_keymap **exist_km, *km; |
| |
| if (!ct->helper || strcmp(ct->helper->name, "pptp")) { |
| DEBUGP("refusing to add GRE keymap to non-pptp session\n"); |
| return -1; |
| } |
| |
| if (!reply) |
| exist_km = &ct->help.ct_pptp_info.keymap_orig; |
| else |
| exist_km = &ct->help.ct_pptp_info.keymap_reply; |
| |
| if (*exist_km) { |
| /* check whether it's a retransmission */ |
| list_for_each_entry(km, &gre_keymap_list, list) { |
| if (gre_key_cmpfn(km, t) && km == *exist_km) |
| return 0; |
| } |
| DEBUGP("trying to override keymap_%s for ct %p\n", |
| reply? "reply":"orig", ct); |
| return -EEXIST; |
| } |
| |
| km = kmalloc(sizeof(*km), GFP_ATOMIC); |
| if (!km) |
| return -ENOMEM; |
| |
| memcpy(&km->tuple, t, sizeof(*t)); |
| *exist_km = km; |
| |
| DEBUGP("adding new entry %p: ", km); |
| DUMP_TUPLE_GRE(&km->tuple); |
| |
| write_lock_bh(&ip_ct_gre_lock); |
| list_add_tail(&km->list, &gre_keymap_list); |
| write_unlock_bh(&ip_ct_gre_lock); |
| |
| return 0; |
| } |
| |
| /* destroy the keymap entries associated with specified master ct */ |
| void ip_ct_gre_keymap_destroy(struct ip_conntrack *ct) |
| { |
| DEBUGP("entering for ct %p\n", ct); |
| |
| if (!ct->helper || strcmp(ct->helper->name, "pptp")) { |
| DEBUGP("refusing to destroy GRE keymap to non-pptp session\n"); |
| return; |
| } |
| |
| write_lock_bh(&ip_ct_gre_lock); |
| if (ct->help.ct_pptp_info.keymap_orig) { |
| DEBUGP("removing %p from list\n", |
| ct->help.ct_pptp_info.keymap_orig); |
| list_del(&ct->help.ct_pptp_info.keymap_orig->list); |
| kfree(ct->help.ct_pptp_info.keymap_orig); |
| ct->help.ct_pptp_info.keymap_orig = NULL; |
| } |
| if (ct->help.ct_pptp_info.keymap_reply) { |
| DEBUGP("removing %p from list\n", |
| ct->help.ct_pptp_info.keymap_reply); |
| list_del(&ct->help.ct_pptp_info.keymap_reply->list); |
| kfree(ct->help.ct_pptp_info.keymap_reply); |
| ct->help.ct_pptp_info.keymap_reply = NULL; |
| } |
| write_unlock_bh(&ip_ct_gre_lock); |
| } |
| |
| |
| /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */ |
| |
| /* invert gre part of tuple */ |
| static int gre_invert_tuple(struct ip_conntrack_tuple *tuple, |
| const struct ip_conntrack_tuple *orig) |
| { |
| tuple->dst.u.gre.key = orig->src.u.gre.key; |
| tuple->src.u.gre.key = orig->dst.u.gre.key; |
| |
| return 1; |
| } |
| |
| /* gre hdr info to tuple */ |
| static int gre_pkt_to_tuple(const struct sk_buff *skb, |
| unsigned int dataoff, |
| struct ip_conntrack_tuple *tuple) |
| { |
| struct gre_hdr_pptp _pgrehdr, *pgrehdr; |
| __be16 srckey; |
| struct gre_hdr _grehdr, *grehdr; |
| |
| /* first only delinearize old RFC1701 GRE header */ |
| grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr); |
| if (!grehdr || grehdr->version != GRE_VERSION_PPTP) { |
| /* try to behave like "ip_conntrack_proto_generic" */ |
| tuple->src.u.all = 0; |
| tuple->dst.u.all = 0; |
| return 1; |
| } |
| |
| /* PPTP header is variable length, only need up to the call_id field */ |
| pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr); |
| if (!pgrehdr) |
| return 1; |
| |
| if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) { |
| DEBUGP("GRE_VERSION_PPTP but unknown proto\n"); |
| return 0; |
| } |
| |
| tuple->dst.u.gre.key = pgrehdr->call_id; |
| srckey = gre_keymap_lookup(tuple); |
| tuple->src.u.gre.key = srckey; |
| |
| return 1; |
| } |
| |
| /* print gre part of tuple */ |
| static int gre_print_tuple(struct seq_file *s, |
| const struct ip_conntrack_tuple *tuple) |
| { |
| return seq_printf(s, "srckey=0x%x dstkey=0x%x ", |
| ntohs(tuple->src.u.gre.key), |
| ntohs(tuple->dst.u.gre.key)); |
| } |
| |
| /* print private data for conntrack */ |
| static int gre_print_conntrack(struct seq_file *s, |
| const struct ip_conntrack *ct) |
| { |
| return seq_printf(s, "timeout=%u, stream_timeout=%u ", |
| (ct->proto.gre.timeout / HZ), |
| (ct->proto.gre.stream_timeout / HZ)); |
| } |
| |
| /* Returns verdict for packet, and may modify conntrack */ |
| static int gre_packet(struct ip_conntrack *ct, |
| const struct sk_buff *skb, |
| enum ip_conntrack_info conntrackinfo) |
| { |
| /* If we've seen traffic both ways, this is a GRE connection. |
| * Extend timeout. */ |
| if (ct->status & IPS_SEEN_REPLY) { |
| ip_ct_refresh_acct(ct, conntrackinfo, skb, |
| ct->proto.gre.stream_timeout); |
| /* Also, more likely to be important, and not a probe. */ |
| set_bit(IPS_ASSURED_BIT, &ct->status); |
| ip_conntrack_event_cache(IPCT_STATUS, skb); |
| } else |
| ip_ct_refresh_acct(ct, conntrackinfo, skb, |
| ct->proto.gre.timeout); |
| |
| return NF_ACCEPT; |
| } |
| |
| /* Called when a new connection for this protocol found. */ |
| static int gre_new(struct ip_conntrack *ct, |
| const struct sk_buff *skb) |
| { |
| DEBUGP(": "); |
| DUMP_TUPLE_GRE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); |
| |
| /* initialize to sane value. Ideally a conntrack helper |
| * (e.g. in case of pptp) is increasing them */ |
| ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT; |
| ct->proto.gre.timeout = GRE_TIMEOUT; |
| |
| return 1; |
| } |
| |
| /* Called when a conntrack entry has already been removed from the hashes |
| * and is about to be deleted from memory */ |
| static void gre_destroy(struct ip_conntrack *ct) |
| { |
| struct ip_conntrack *master = ct->master; |
| DEBUGP(" entering\n"); |
| |
| if (!master) |
| DEBUGP("no master !?!\n"); |
| else |
| ip_ct_gre_keymap_destroy(master); |
| } |
| |
| /* protocol helper struct */ |
| static struct ip_conntrack_protocol gre = { |
| .proto = IPPROTO_GRE, |
| .name = "gre", |
| .pkt_to_tuple = gre_pkt_to_tuple, |
| .invert_tuple = gre_invert_tuple, |
| .print_tuple = gre_print_tuple, |
| .print_conntrack = gre_print_conntrack, |
| .packet = gre_packet, |
| .new = gre_new, |
| .destroy = gre_destroy, |
| .me = THIS_MODULE, |
| #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ |
| defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) |
| .tuple_to_nfattr = ip_ct_port_tuple_to_nfattr, |
| .nfattr_to_tuple = ip_ct_port_nfattr_to_tuple, |
| #endif |
| }; |
| |
| /* ip_conntrack_proto_gre initialization */ |
| int __init ip_ct_proto_gre_init(void) |
| { |
| return ip_conntrack_protocol_register(&gre); |
| } |
| |
| /* This cannot be __exit, as it is invoked from ip_conntrack_helper_pptp.c's |
| * init() code on errors. |
| */ |
| void ip_ct_proto_gre_fini(void) |
| { |
| struct list_head *pos, *n; |
| |
| /* delete all keymap entries */ |
| write_lock_bh(&ip_ct_gre_lock); |
| list_for_each_safe(pos, n, &gre_keymap_list) { |
| DEBUGP("deleting keymap %p at module unload time\n", pos); |
| list_del(pos); |
| kfree(pos); |
| } |
| write_unlock_bh(&ip_ct_gre_lock); |
| |
| ip_conntrack_protocol_unregister(&gre); |
| } |
| |
| EXPORT_SYMBOL(ip_ct_gre_keymap_add); |
| EXPORT_SYMBOL(ip_ct_gre_keymap_destroy); |