[linux-2.6-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;

	BUG_ON(strcmp(help->helper->name, "pptp"));
	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);
	BUG_ON(strcmp(help->helper->name, "pptp"));

	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_CONNTRACK_NETLINK) || \
    defined(CONFIG_NF_CONNTRACK_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
103	BUG_ON(strcmp(help->helper->name, "pptp"));
104	kmp = &help->help.ct_pptp_info.keymap[dir];
105	if (*kmp) {
106	/* check whether it's a retransmission */
107	list_for_each_entry(km, &gre_keymap_list, list) {
108	if (gre_key_cmpfn(km, t) && km == *kmp)
109	return 0;
110	}
111	DEBUGP("trying to override keymap_%s for ct %p\n",
112	dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
113	return -EEXIST;
114	}
115
116	km = kmalloc(sizeof(*km), GFP_ATOMIC);
117	if (!km)
118	return -ENOMEM;
119	memcpy(&km->tuple, t, sizeof(*t));
120	*kmp = km;
121
122	DEBUGP("adding new entry %p: ", km);
123	NF_CT_DUMP_TUPLE(&km->tuple);
124
125	write_lock_bh(&nf_ct_gre_lock);
126	list_add_tail(&km->list, &gre_keymap_list);
127	write_unlock_bh(&nf_ct_gre_lock);
128
129	return 0;
130	}
131	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
132
133	/* destroy the keymap entries associated with specified master ct */
134	void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
135	{
136	struct nf_conn_help *help = nfct_help(ct);
137	enum ip_conntrack_dir dir;
138
139	DEBUGP("entering for ct %p\n", ct);
140	BUG_ON(strcmp(help->helper->name, "pptp"));
141
142	write_lock_bh(&nf_ct_gre_lock);
143	for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
144	if (help->help.ct_pptp_info.keymap[dir]) {
145	DEBUGP("removing %p from list\n",
146	help->help.ct_pptp_info.keymap[dir]);
147	list_del(&help->help.ct_pptp_info.keymap[dir]->list);
148	kfree(help->help.ct_pptp_info.keymap[dir]);
149	help->help.ct_pptp_info.keymap[dir] = NULL;
150	}
151	}
152	write_unlock_bh(&nf_ct_gre_lock);
153	}
154	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
155
156	/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
157
158	/* invert gre part of tuple */
159	static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
160	const struct nf_conntrack_tuple *orig)
161	{
162	tuple->dst.u.gre.key = orig->src.u.gre.key;
163	tuple->src.u.gre.key = orig->dst.u.gre.key;
164	return 1;
165	}
166
167	/* gre hdr info to tuple */
168	static int gre_pkt_to_tuple(const struct sk_buff *skb,
169	unsigned int dataoff,
170	struct nf_conntrack_tuple *tuple)
171	{
172	struct gre_hdr_pptp _pgrehdr, *pgrehdr;
173	__be16 srckey;
174	struct gre_hdr _grehdr, *grehdr;
175
176	/* first only delinearize old RFC1701 GRE header */
177	grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
178	if (!grehdr \|\| grehdr->version != GRE_VERSION_PPTP) {
179	/* try to behave like "nf_conntrack_proto_generic" */
180	tuple->src.u.all = 0;
181	tuple->dst.u.all = 0;
182	return 1;
183	}
184
185	/* PPTP header is variable length, only need up to the call_id field */
186	pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
187	if (!pgrehdr)
188	return 1;
189
190	if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
191	DEBUGP("GRE_VERSION_PPTP but unknown proto\n");
192	return 0;
193	}
194
195	tuple->dst.u.gre.key = pgrehdr->call_id;
196	srckey = gre_keymap_lookup(tuple);
197	tuple->src.u.gre.key = srckey;
198
199	return 1;
200	}
201
202	/* print gre part of tuple */
203	static int gre_print_tuple(struct seq_file *s,
204	const struct nf_conntrack_tuple *tuple)
205	{
206	return seq_printf(s, "srckey=0x%x dstkey=0x%x ",
207	ntohs(tuple->src.u.gre.key),
208	ntohs(tuple->dst.u.gre.key));
209	}
210
211	/* print private data for conntrack */
212	static int gre_print_conntrack(struct seq_file *s,
213	const struct nf_conn *ct)
214	{
215	return seq_printf(s, "timeout=%u, stream_timeout=%u ",
216	(ct->proto.gre.timeout / HZ),
217	(ct->proto.gre.stream_timeout / HZ));
218	}
219
220	/* Returns verdict for packet, and may modify conntrack */
221	static int gre_packet(struct nf_conn *ct,
222	const struct sk_buff *skb,
223	unsigned int dataoff,
224	enum ip_conntrack_info ctinfo,
225	int pf,
226	unsigned int hooknum)
227	{
228	/* If we've seen traffic both ways, this is a GRE connection.
229	* Extend timeout. */
230	if (ct->status & IPS_SEEN_REPLY) {
231	nf_ct_refresh_acct(ct, ctinfo, skb,
232	ct->proto.gre.stream_timeout);
233	/* Also, more likely to be important, and not a probe. */
234	set_bit(IPS_ASSURED_BIT, &ct->status);
235	nf_conntrack_event_cache(IPCT_STATUS, skb);
236	} else
237	nf_ct_refresh_acct(ct, ctinfo, skb,
238	ct->proto.gre.timeout);
239
240	return NF_ACCEPT;
241	}
242
243	/* Called when a new connection for this protocol found. */
244	static int gre_new(struct nf_conn ct, const struct sk_buff skb,
245	unsigned int dataoff)
246	{
247	DEBUGP(": ");
248	NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
249
250	/* initialize to sane value. Ideally a conntrack helper
251	* (e.g. in case of pptp) is increasing them */
252	ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT;
253	ct->proto.gre.timeout = GRE_TIMEOUT;
254
255	return 1;
256	}
257
258	/* Called when a conntrack entry has already been removed from the hashes
259	* and is about to be deleted from memory */
260	static void gre_destroy(struct nf_conn *ct)
261	{
262	struct nf_conn *master = ct->master;
263	DEBUGP(" entering\n");
264
265	if (!master)
266	DEBUGP("no master !?!\n");
267	else
268	nf_ct_gre_keymap_destroy(master);
269	}
270
271	/* protocol helper struct */
272	static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 = {
273	.l3proto = AF_INET,
274	.l4proto = IPPROTO_GRE,
275	.name = "gre",
276	.pkt_to_tuple = gre_pkt_to_tuple,
277	.invert_tuple = gre_invert_tuple,
278	.print_tuple = gre_print_tuple,
279	.print_conntrack = gre_print_conntrack,
280	.packet = gre_packet,
281	.new = gre_new,
282	.destroy = gre_destroy,
283	.me = THIS_MODULE,
284	#if defined(CONFIG_NF_CONNTRACK_NETLINK) \|\| \
285	defined(CONFIG_NF_CONNTRACK_NETLINK_MODULE)
286	.tuple_to_nfattr = nf_ct_port_tuple_to_nfattr,
287	.nfattr_to_tuple = nf_ct_port_nfattr_to_tuple,
288	#endif
289	};
290
291	static int __init nf_ct_proto_gre_init(void)
292	{
293	return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
294	}
295
296	static void nf_ct_proto_gre_fini(void)
297	{
298	nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
299	nf_ct_gre_keymap_flush();
300	}
301
302	module_init(nf_ct_proto_gre_init);
303	module_exit(nf_ct_proto_gre_fini);
304
305	MODULE_LICENSE("GPL");