[mirror_ubuntu-artful-kernel.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)

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);

	pr_debug("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;
		}
		pr_debug("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;

	pr_debug("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;

	pr_debug("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]) {
			pr_debug("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)
{
	const struct gre_hdr_pptp *pgrehdr;
	struct gre_hdr_pptp _pgrehdr;
	__be16 srckey;
	const struct gre_hdr *grehdr;
	struct gre_hdr _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) {
		pr_debug("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)
{
	pr_debug(": ");
	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;
	pr_debug(" entering\n");

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

/* protocol helper struct */
static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly = {
	.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_nlattr = nf_ct_port_tuple_to_nlattr,
	.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
	.nla_policy	 = nf_ct_port_nla_policy,
#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
f09943fe PM	43	static DEFINE_RWLOCK(nf_ct_gre_lock);
	44	static LIST_HEAD(gre_keymap_list);
	45
	46	void nf_ct_gre_keymap_flush(void)
	47	{
	48	struct list_head pos, n;
	49
	50	write_lock_bh(&nf_ct_gre_lock);
	51	list_for_each_safe(pos, n, &gre_keymap_list) {
	52	list_del(pos);
	53	kfree(pos);
	54	}
	55	write_unlock_bh(&nf_ct_gre_lock);
	56	}
	57	EXPORT_SYMBOL(nf_ct_gre_keymap_flush);
	58
	59	static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
	60	const struct nf_conntrack_tuple *t)
	61	{
	62	return km->tuple.src.l3num == t->src.l3num &&
	63	!memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
	64	!memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
	65	km->tuple.dst.protonum == t->dst.protonum &&
	66	km->tuple.dst.u.all == t->dst.u.all;
	67	}
	68
	69	/* look up the source key for a given tuple */
	70	static __be16 gre_keymap_lookup(struct nf_conntrack_tuple *t)
	71	{
	72	struct nf_ct_gre_keymap *km;
	73	__be16 key = 0;
	74
	75	read_lock_bh(&nf_ct_gre_lock);
	76	list_for_each_entry(km, &gre_keymap_list, list) {
	77	if (gre_key_cmpfn(km, t)) {
	78	key = km->tuple.src.u.gre.key;
	79	break;
	80	}
	81	}
	82	read_unlock_bh(&nf_ct_gre_lock);
	83
0d53778e	84	pr_debug("lookup src key 0x%x for ", key);
f09943fe PM	85	NF_CT_DUMP_TUPLE(t);
	86
	87	return key;
	88	}
	89
	90	/* add a single keymap entry, associate with specified master ct */
	91	int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
	92	struct nf_conntrack_tuple *t)
	93	{
	94	struct nf_conn_help *help = nfct_help(ct);
	95	struct nf_ct_gre_keymap *kmp, km;
	96
f09943fe PM	97	kmp = &help->help.ct_pptp_info.keymap[dir];
	98	if (*kmp) {
	99	/* check whether it's a retransmission */
	100	list_for_each_entry(km, &gre_keymap_list, list) {
	101	if (gre_key_cmpfn(km, t) && km == *kmp)
	102	return 0;
	103	}
0d53778e PM	104	pr_debug("trying to override keymap_%s for ct %p\n",
0d53778e PM	105	dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
f09943fe PM	106	return -EEXIST;
	107	}
	108
	109	km = kmalloc(sizeof(*km), GFP_ATOMIC);
	110	if (!km)
	111	return -ENOMEM;
	112	memcpy(&km->tuple, t, sizeof(*t));
	113	*kmp = km;
	114
0d53778e	115	pr_debug("adding new entry %p: ", km);
f09943fe PM	116	NF_CT_DUMP_TUPLE(&km->tuple);
	117
	118	write_lock_bh(&nf_ct_gre_lock);
	119	list_add_tail(&km->list, &gre_keymap_list);
	120	write_unlock_bh(&nf_ct_gre_lock);
	121
	122	return 0;
	123	}
	124	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
	125
	126	/* destroy the keymap entries associated with specified master ct */
	127	void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
	128	{
	129	struct nf_conn_help *help = nfct_help(ct);
	130	enum ip_conntrack_dir dir;
	131
0d53778e	132	pr_debug("entering for ct %p\n", ct);
f09943fe PM	133
	134	write_lock_bh(&nf_ct_gre_lock);
	135	for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
	136	if (help->help.ct_pptp_info.keymap[dir]) {
0d53778e PM	137	pr_debug("removing %p from list\n",
0d53778e PM	138	help->help.ct_pptp_info.keymap[dir]);
f09943fe PM	139	list_del(&help->help.ct_pptp_info.keymap[dir]->list);
	140	kfree(help->help.ct_pptp_info.keymap[dir]);
	141	help->help.ct_pptp_info.keymap[dir] = NULL;
	142	}
	143	}
	144	write_unlock_bh(&nf_ct_gre_lock);
	145	}
	146	EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
	147
	148	/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
	149
	150	/* invert gre part of tuple */
	151	static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
	152	const struct nf_conntrack_tuple *orig)
	153	{
	154	tuple->dst.u.gre.key = orig->src.u.gre.key;
	155	tuple->src.u.gre.key = orig->dst.u.gre.key;
	156	return 1;
	157	}
	158
	159	/* gre hdr info to tuple */
	160	static int gre_pkt_to_tuple(const struct sk_buff *skb,
	161	unsigned int dataoff,
	162	struct nf_conntrack_tuple *tuple)
	163	{
dc35dc5a JE	164	const struct gre_hdr_pptp *pgrehdr;
dc35dc5a JE	165	struct gre_hdr_pptp _pgrehdr;
f09943fe	166	__be16 srckey;
dc35dc5a JE	167	const struct gre_hdr *grehdr;
dc35dc5a JE	168	struct gre_hdr _grehdr;
f09943fe PM	169
	170	/* first only delinearize old RFC1701 GRE header */
	171	grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
	172	if (!grehdr \|\| grehdr->version != GRE_VERSION_PPTP) {
	173	/* try to behave like "nf_conntrack_proto_generic" */
	174	tuple->src.u.all = 0;
	175	tuple->dst.u.all = 0;
	176	return 1;
	177	}
	178
	179	/* PPTP header is variable length, only need up to the call_id field */
	180	pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
	181	if (!pgrehdr)
	182	return 1;
	183
	184	if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
0d53778e	185	pr_debug("GRE_VERSION_PPTP but unknown proto\n");
f09943fe PM	186	return 0;
	187	}
	188
	189	tuple->dst.u.gre.key = pgrehdr->call_id;
	190	srckey = gre_keymap_lookup(tuple);
	191	tuple->src.u.gre.key = srckey;
	192
	193	return 1;
	194	}
	195
	196	/* print gre part of tuple */
	197	static int gre_print_tuple(struct seq_file *s,
	198	const struct nf_conntrack_tuple *tuple)
	199	{
	200	return seq_printf(s, "srckey=0x%x dstkey=0x%x ",
	201	ntohs(tuple->src.u.gre.key),
	202	ntohs(tuple->dst.u.gre.key));
	203	}
	204
	205	/* print private data for conntrack */
	206	static int gre_print_conntrack(struct seq_file *s,
	207	const struct nf_conn *ct)
	208	{
	209	return seq_printf(s, "timeout=%u, stream_timeout=%u ",
	210	(ct->proto.gre.timeout / HZ),
	211	(ct->proto.gre.stream_timeout / HZ));
	212	}
	213
	214	/* Returns verdict for packet, and may modify conntrack */
	215	static int gre_packet(struct nf_conn *ct,
	216	const struct sk_buff *skb,
	217	unsigned int dataoff,
	218	enum ip_conntrack_info ctinfo,
	219	int pf,
	220	unsigned int hooknum)
	221	{
	222	/* If we've seen traffic both ways, this is a GRE connection.
	223	* Extend timeout. */
	224	if (ct->status & IPS_SEEN_REPLY) {
	225	nf_ct_refresh_acct(ct, ctinfo, skb,
	226	ct->proto.gre.stream_timeout);
	227	/* Also, more likely to be important, and not a probe. */
	228	set_bit(IPS_ASSURED_BIT, &ct->status);
	229	nf_conntrack_event_cache(IPCT_STATUS, skb);
	230	} else
	231	nf_ct_refresh_acct(ct, ctinfo, skb,
	232	ct->proto.gre.timeout);
	233
	234	return NF_ACCEPT;
	235	}
	236
	237	/* Called when a new connection for this protocol found. */
	238	static int gre_new(struct nf_conn ct, const struct sk_buff skb,
	239	unsigned int dataoff)
	240	{
0d53778e	241	pr_debug(": ");
f09943fe PM	242	NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
	243
	244	/* initialize to sane value. Ideally a conntrack helper
	245	* (e.g. in case of pptp) is increasing them */
	246	ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT;
	247	ct->proto.gre.timeout = GRE_TIMEOUT;
	248
	249	return 1;
	250	}
	251
	252	/* Called when a conntrack entry has already been removed from the hashes
	253	* and is about to be deleted from memory */
	254	static void gre_destroy(struct nf_conn *ct)
	255	{
	256	struct nf_conn *master = ct->master;
0d53778e	257	pr_debug(" entering\n");
f09943fe PM	258
f09943fe PM	259	if (!master)
0d53778e	260	pr_debug("no master !?!\n");
f09943fe PM	261	else
	262	nf_ct_gre_keymap_destroy(master);
	263	}
	264
	265	/* protocol helper struct */
61075af5	266	static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly = {
f09943fe PM	267	.l3proto = AF_INET,
	268	.l4proto = IPPROTO_GRE,
	269	.name = "gre",
	270	.pkt_to_tuple = gre_pkt_to_tuple,
	271	.invert_tuple = gre_invert_tuple,
	272	.print_tuple = gre_print_tuple,
	273	.print_conntrack = gre_print_conntrack,
	274	.packet = gre_packet,
	275	.new = gre_new,
	276	.destroy = gre_destroy,
	277	.me = THIS_MODULE,
e281db5c	278	#if defined(CONFIG_NF_CT_NETLINK) \|\| defined(CONFIG_NF_CT_NETLINK_MODULE)
fdf70832 PM	279	.tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
fdf70832 PM	280	.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
f73e924c	281	.nla_policy = nf_ct_port_nla_policy,
f09943fe PM	282	#endif
	283	};
	284
	285	static int __init nf_ct_proto_gre_init(void)
	286	{
	287	return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
	288	}
	289
	290	static void nf_ct_proto_gre_fini(void)
	291	{
	292	nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
	293	nf_ct_gre_keymap_flush();
	294	}
	295
	296	module_init(nf_ct_proto_gre_init);
	297	module_exit(nf_ct_proto_gre_fini);
	298
	299	MODULE_LICENSE("GPL");