[linux-block.git] / net / netfilter / nf_conntrack_proto_gre.c

/*
 * 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/list.h>
#include <linux/seq_file.h>
#include <linux/in.h>
#include <linux/skbuff.h>

#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <linux/netfilter/nf_conntrack_proto_gre.h>
#include <linux/netfilter/nf_conntrack_pptp.h>

#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)
#else
#define DEBUGP(x, args...)
#endif

static DEFINE_RWLOCK(nf_ct_gre_lock);
static LIST_HEAD(gre_keymap_list);

void nf_ct_gre_keymap_flush(void)
{
	struct list_head *pos, *n;

	write_lock_bh(&nf_ct_gre_lock);
	list_for_each_safe(pos, n, &gre_keymap_list) {
		list_del(pos);
		kfree(pos);
	}
	write_unlock_bh(&nf_ct_gre_lock);
}
EXPORT_SYMBOL(nf_ct_gre_keymap_flush);

static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
				const struct nf_conntrack_tuple *t)
{
	return km->tuple.src.l3num == t->src.l3num &&
	       !memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
	       !memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
	       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 nf_conntrack_tuple *t)
{
	struct nf_ct_gre_keymap *km;
	__be16 key = 0;

	read_lock_bh(&nf_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(&nf_ct_gre_lock);

	DEBUGP("lookup src key 0x%x for ", key);
	NF_CT_DUMP_TUPLE(t);

	return key;
}

/* add a single keymap entry, associate with specified master ct */
int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
			 struct nf_conntrack_tuple *t)
{
	struct nf_conn_help *help = nfct_help(ct);
	struct nf_ct_gre_keymap **kmp, *km;

	kmp = &help->help.ct_pptp_info.keymap[dir];
	if (*kmp) {
		/* check whether it's a retransmission */
		list_for_each_entry(km, &gre_keymap_list, list) {
			if (gre_key_cmpfn(km, t) && km == *kmp)
				return 0;
		}
		DEBUGP("trying to override keymap_%s for ct %p\n",
			dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
		return -EEXIST;
	}

	km = kmalloc(sizeof(*km), GFP_ATOMIC);
	if (!km)
		return -ENOMEM;
	memcpy(&km->tuple, t, sizeof(*t));
	*kmp = km;

	DEBUGP("adding new entry %p: ", km);
	NF_CT_DUMP_TUPLE(&km->tuple);

	write_lock_bh(&nf_ct_gre_lock);
	list_add_tail(&km->list, &gre_keymap_list);
	write_unlock_bh(&nf_ct_gre_lock);

	return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);

/* destroy the keymap entries associated with specified master ct */
void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
{
	struct nf_conn_help *help = nfct_help(ct);
	enum ip_conntrack_dir dir;

	DEBUGP("entering for ct %p\n", ct);

	write_lock_bh(&nf_ct_gre_lock);
	for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
		if (help->help.ct_pptp_info.keymap[dir]) {
			DEBUGP("removing %p from list\n",
				help->help.ct_pptp_info.keymap[dir]);
			list_del(&help->help.ct_pptp_info.keymap[dir]->list);
			kfree(help->help.ct_pptp_info.keymap[dir]);
			help->help.ct_pptp_info.keymap[dir] = NULL;
		}
	}
	write_unlock_bh(&nf_ct_gre_lock);
}
EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);

/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */

/* invert gre part of tuple */
static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
			    const struct nf_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 nf_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 "nf_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 nf_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 nf_conn *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 nf_conn *ct,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      int pf,
		      unsigned int hooknum)
{
	/* If we've seen traffic both ways, this is a GRE connection.
	 * Extend timeout. */
	if (ct->status & IPS_SEEN_REPLY) {
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   ct->proto.gre.stream_timeout);
		/* Also, more likely to be important, and not a probe. */
		set_bit(IPS_ASSURED_BIT, &ct->status);
		nf_conntrack_event_cache(IPCT_STATUS, skb);
	} else
		nf_ct_refresh_acct(ct, ctinfo, skb,
				   ct->proto.gre.timeout);

	return NF_ACCEPT;
}

/* Called when a new connection for this protocol found. */
static int gre_new(struct nf_conn *ct, const struct sk_buff *skb,
		   unsigned int dataoff)
{
	DEBUGP(": ");
	NF_CT_DUMP_TUPLE(&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 nf_conn *ct)
{
	struct nf_conn *master = ct->master;
	DEBUGP(" entering\n");

	if (!master)
		DEBUGP("no master !?!\n");
	else
		nf_ct_gre_keymap_destroy(master);
}

/* protocol helper struct */
static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 = {
	.l3proto	 = AF_INET,
	.l4proto	 = 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_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
	.tuple_to_nfattr = nf_ct_port_tuple_to_nfattr,
	.nfattr_to_tuple = nf_ct_port_nfattr_to_tuple,
#endif
};

static int __init nf_ct_proto_gre_init(void)
{
	return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
}

static void nf_ct_proto_gre_fini(void)
{
	nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
	nf_ct_gre_keymap_flush();
}

module_init(nf_ct_proto_gre_init);
module_exit(nf_ct_proto_gre_fini);

MODULE_LICENSE("GPL");
Commit	Line	Data
f09943fe PM	1	/*
	2	* ip_conntrack_proto_gre.c - Version 3.0
	3	*
	4	* Connection tracking protocol helper module for GRE.
	5	*
	6	* GRE is a generic encapsulation protocol, which is generally not very
	7	* suited for NAT, as it has no protocol-specific part as port numbers.
	8	*
	9	* It has an optional key field, which may help us distinguishing two
	10	* connections between the same two hosts.
	11	*
	12	* GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
	13	*
	14	* PPTP is built on top of a modified version of GRE, and has a mandatory
	15	* field called "CallID", which serves us for the same purpose as the key
	16	* field in plain GRE.
	17	*
	18	* Documentation about PPTP can be found in RFC 2637
	19	*
	20	* (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
	21	*
	22	* Development of this code funded by Astaro AG (http://www.astaro.com/)
	23	*
	24	*/
	25
	26	#include <linux/module.h>
	27	#include <linux/types.h>
	28	#include <linux/timer.h>
	29	#include <linux/list.h>
	30	#include <linux/seq_file.h>
	31	#include <linux/in.h>
	32	#include <linux/skbuff.h>
	33
	34	#include <net/netfilter/nf_conntrack_l4proto.h>
	35	#include <net/netfilter/nf_conntrack_helper.h>
	36	#include <net/netfilter/nf_conntrack_core.h>
	37	#include <linux/netfilter/nf_conntrack_proto_gre.h>
	38	#include <linux/netfilter/nf_conntrack_pptp.h>
	39
	40	#define GRE_TIMEOUT (30 * HZ)
	41	#define GRE_STREAM_TIMEOUT (180 * HZ)
	42
	43	#if 0
	44	#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s: " format, __FILE__, __FUNCTION__, ## args)
	45	#else
	46	#define DEBUGP(x, args...)
	47	#endif
	48
	49	static DEFINE_RWLOCK(nf_ct_gre_lock);
	50	static LIST_HEAD(gre_keymap_list);
	51
	52	void nf_ct_gre_keymap_flush(void)
	53	{
	54	struct list_head pos, n;
	55
	56	write_lock_bh(&nf_ct_gre_lock);
	57	list_for_each_safe(pos, n, &gre_keymap_list) {
	58	list_del(pos);
	59	kfree(pos);
	60	}
	61	write_unlock_bh(&nf_ct_gre_lock);
	62	}
	63	EXPORT_SYMBOL(nf_ct_gre_keymap_flush);
	64
65	static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
66	const struct nf_conntrack_tuple *t)
67	{
68	return km->tuple.src.l3num == t->src.l3num &&
69	!memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
70	!memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
71	km->tuple.dst.protonum == t->dst.protonum &&
72	km->tuple.dst.u.all == t->dst.u.all;
73	}
74
75	/* look up the source key for a given tuple */
76	static __be16 gre_keymap_lookup(struct nf_conntrack_tuple *t)
77	{
78	struct nf_ct_gre_keymap *km;
79	__be16 key = 0;
80
81	read_lock_bh(&nf_ct_gre_lock);
82	list_for_each_entry(km, &gre_keymap_list, list) {
83	if (gre_key_cmpfn(km, t)) {
84	key = km->tuple.src.u.gre.key;
85	break;
86	}
87	}
88	read_unlock_bh(&nf_ct_gre_lock);
89
90	DEBUGP("lookup src key 0x%x for ", key);
91	NF_CT_DUMP_TUPLE(t);
92
93	return key;
94	}
95
96	/* add a single keymap entry, associate with specified master ct */
97	int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
98	struct nf_conntrack_tuple *t)
99	{
100	struct nf_conn_help *help = nfct_help(ct);
101	struct nf_ct_gre_keymap *kmp, km;
102
f09943fe PM	103	kmp = &help->help.ct_pptp_info.keymap[dir];
	104	if (*kmp) {
	105	/* check whether it's a retransmission */
	106	list_for_each_entry(km, &gre_keymap_list, list) {
	107	if (gre_key_cmpfn(km, t) && km == *kmp)
	108	return 0;
	109	}
	110	DEBUGP("trying to override keymap_%s for ct %p\n",
	111	dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
	112	return -EEXIST;
	113	}
	114
	115	km = kmalloc(sizeof(*km), GFP_ATOMIC);
	116	if (!km)
	117	return -ENOMEM;
	118	memcpy(&km->tuple, t, sizeof(*t));
	119	*kmp = km;
	120
	121	DEBUGP("adding new entry %p: ", km);
	122	NF_CT_DUMP_TUPLE(&km->tuple);
	123
	124	write_lock_bh(&nf_ct_gre_lock);
	125	list_add_tail(&km->list, &gre_keymap_list);
	126	write_unlock_bh(&nf_ct_gre_lock);
	127
	128	return 0;
	129	}
	130	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
	131
	132	/* destroy the keymap entries associated with specified master ct */
	133	void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
	134	{
	135	struct nf_conn_help *help = nfct_help(ct);
	136	enum ip_conntrack_dir dir;
	137
	138	DEBUGP("entering for ct %p\n", ct);
f09943fe PM	139
	140	write_lock_bh(&nf_ct_gre_lock);
	141	for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
	142	if (help->help.ct_pptp_info.keymap[dir]) {
	143	DEBUGP("removing %p from list\n",
	144	help->help.ct_pptp_info.keymap[dir]);
	145	list_del(&help->help.ct_pptp_info.keymap[dir]->list);
	146	kfree(help->help.ct_pptp_info.keymap[dir]);
	147	help->help.ct_pptp_info.keymap[dir] = NULL;
	148	}
	149	}
	150	write_unlock_bh(&nf_ct_gre_lock);
	151	}
	152	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
	153
	154	/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
	155
	156	/* invert gre part of tuple */
	157	static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
	158	const struct nf_conntrack_tuple *orig)
	159	{
	160	tuple->dst.u.gre.key = orig->src.u.gre.key;
	161	tuple->src.u.gre.key = orig->dst.u.gre.key;
	162	return 1;
	163	}
	164
	165	/* gre hdr info to tuple */
	166	static int gre_pkt_to_tuple(const struct sk_buff *skb,
	167	unsigned int dataoff,
	168	struct nf_conntrack_tuple *tuple)
	169	{
	170	struct gre_hdr_pptp _pgrehdr, *pgrehdr;
	171	__be16 srckey;
	172	struct gre_hdr _grehdr, *grehdr;
	173
	174	/* first only delinearize old RFC1701 GRE header */
	175	grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
	176	if (!grehdr \|\| grehdr->version != GRE_VERSION_PPTP) {
	177	/* try to behave like "nf_conntrack_proto_generic" */
	178	tuple->src.u.all = 0;
	179	tuple->dst.u.all = 0;
	180	return 1;
	181	}
	182
	183	/* PPTP header is variable length, only need up to the call_id field */
	184	pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
	185	if (!pgrehdr)
	186	return 1;
	187
	188	if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
	189	DEBUGP("GRE_VERSION_PPTP but unknown proto\n");
	190	return 0;
	191	}
	192
	193	tuple->dst.u.gre.key = pgrehdr->call_id;
	194	srckey = gre_keymap_lookup(tuple);
	195	tuple->src.u.gre.key = srckey;
	196
	197	return 1;
	198	}
	199
	200	/* print gre part of tuple */
	201	static int gre_print_tuple(struct seq_file *s,
	202	const struct nf_conntrack_tuple *tuple)
203	{
204	return seq_printf(s, "srckey=0x%x dstkey=0x%x ",
205	ntohs(tuple->src.u.gre.key),
206	ntohs(tuple->dst.u.gre.key));
207	}
208
209	/* print private data for conntrack */
210	static int gre_print_conntrack(struct seq_file *s,
211	const struct nf_conn *ct)
212	{
213	return seq_printf(s, "timeout=%u, stream_timeout=%u ",
214	(ct->proto.gre.timeout / HZ),
215	(ct->proto.gre.stream_timeout / HZ));
216	}
217
218	/* Returns verdict for packet, and may modify conntrack */
219	static int gre_packet(struct nf_conn *ct,
220	const struct sk_buff *skb,
221	unsigned int dataoff,
222	enum ip_conntrack_info ctinfo,
223	int pf,
224	unsigned int hooknum)
225	{
226	/* If we've seen traffic both ways, this is a GRE connection.
227	* Extend timeout. */
228	if (ct->status & IPS_SEEN_REPLY) {
229	nf_ct_refresh_acct(ct, ctinfo, skb,
230	ct->proto.gre.stream_timeout);
231	/* Also, more likely to be important, and not a probe. */
232	set_bit(IPS_ASSURED_BIT, &ct->status);
233	nf_conntrack_event_cache(IPCT_STATUS, skb);
234	} else
235	nf_ct_refresh_acct(ct, ctinfo, skb,
236	ct->proto.gre.timeout);
237
238	return NF_ACCEPT;
239	}
240
241	/* Called when a new connection for this protocol found. */
242	static int gre_new(struct nf_conn ct, const struct sk_buff skb,
243	unsigned int dataoff)
244	{
245	DEBUGP(": ");
246	NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
247
248	/* initialize to sane value. Ideally a conntrack helper
249	* (e.g. in case of pptp) is increasing them */
250	ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT;
251	ct->proto.gre.timeout = GRE_TIMEOUT;
252
253	return 1;
254	}
255
256	/* Called when a conntrack entry has already been removed from the hashes
257	* and is about to be deleted from memory */
258	static void gre_destroy(struct nf_conn *ct)
259	{
260	struct nf_conn *master = ct->master;
261	DEBUGP(" entering\n");
262
263	if (!master)
264	DEBUGP("no master !?!\n");
265	else
266	nf_ct_gre_keymap_destroy(master);
267	}
268
269	/* protocol helper struct */
270	static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 = {
271	.l3proto = AF_INET,
272	.l4proto = IPPROTO_GRE,
273	.name = "gre",
274	.pkt_to_tuple = gre_pkt_to_tuple,
275	.invert_tuple = gre_invert_tuple,
276	.print_tuple = gre_print_tuple,
277	.print_conntrack = gre_print_conntrack,
278	.packet = gre_packet,
279	.new = gre_new,
280	.destroy = gre_destroy,
281	.me = THIS_MODULE,
e281db5c	282	#if defined(CONFIG_NF_CT_NETLINK) \|\| defined(CONFIG_NF_CT_NETLINK_MODULE)
f09943fe PM	283	.tuple_to_nfattr = nf_ct_port_tuple_to_nfattr,
	284	.nfattr_to_tuple = nf_ct_port_nfattr_to_tuple,
	285	#endif
	286	};
	287
	288	static int __init nf_ct_proto_gre_init(void)
	289	{
	290	return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
	291	}
	292
	293	static void nf_ct_proto_gre_fini(void)
	294	{
	295	nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
	296	nf_ct_gre_keymap_flush();
	297	}
	298
	299	module_init(nf_ct_proto_gre_init);
	300	module_exit(nf_ct_proto_gre_fini);
	301
	302	MODULE_LICENSE("GPL");