[linux-2.6-block.git] / net / ipv4 / gre_demux.c

/*
 *	GRE over IPv4 demultiplexer driver
 *
 *	Authors: Dmitry Kozlov (xeb@mail.ru)
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/if.h>
#include <linux/icmp.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/netdevice.h>
#include <linux/if_tunnel.h>
#include <linux/spinlock.h>
#include <net/protocol.h>
#include <net/gre.h>

#include <net/icmp.h>
#include <net/route.h>
#include <net/xfrm.h>

static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX];

int gre_add_protocol(const struct gre_protocol *proto, u8 version)
{
	if (version >= GREPROTO_MAX)
		return -EINVAL;

	return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
		0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(gre_add_protocol);

int gre_del_protocol(const struct gre_protocol *proto, u8 version)
{
	int ret;

	if (version >= GREPROTO_MAX)
		return -EINVAL;

	ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
		0 : -EBUSY;

	if (ret)
		return ret;

	synchronize_rcu();
	return 0;
}
EXPORT_SYMBOL_GPL(gre_del_protocol);

void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
		      int hdr_len)
{
	struct gre_base_hdr *greh;

	skb_push(skb, hdr_len);

	skb_reset_transport_header(skb);
	greh = (struct gre_base_hdr *)skb->data;
	greh->flags = tnl_flags_to_gre_flags(tpi->flags);
	greh->protocol = tpi->proto;

	if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) {
		__be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);

		if (tpi->flags&TUNNEL_SEQ) {
			*ptr = tpi->seq;
			ptr--;
		}
		if (tpi->flags&TUNNEL_KEY) {
			*ptr = tpi->key;
			ptr--;
		}
		if (tpi->flags&TUNNEL_CSUM &&
		    !(skb_shinfo(skb)->gso_type &
		      (SKB_GSO_GRE|SKB_GSO_GRE_CSUM))) {
			*ptr = 0;
			*(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
								 skb->len, 0));
		}
	}
}
EXPORT_SYMBOL_GPL(gre_build_header);

static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
			    bool *csum_err)
{
	const struct gre_base_hdr *greh;
	__be32 *options;
	int hdr_len;

	if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
		return -EINVAL;

	greh = (struct gre_base_hdr *)skb_transport_header(skb);
	if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
		return -EINVAL;

	tpi->flags = gre_flags_to_tnl_flags(greh->flags);
	hdr_len = ip_gre_calc_hlen(tpi->flags);

	if (!pskb_may_pull(skb, hdr_len))
		return -EINVAL;

	greh = (struct gre_base_hdr *)skb_transport_header(skb);
	tpi->proto = greh->protocol;

	options = (__be32 *)(greh + 1);
	if (greh->flags & GRE_CSUM) {
		if (skb_checksum_simple_validate(skb)) {
			*csum_err = true;
			return -EINVAL;
		}

		skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
					 null_compute_pseudo);

		options++;
	}

	if (greh->flags & GRE_KEY) {
		tpi->key = *options;
		options++;
	} else
		tpi->key = 0;

	if (unlikely(greh->flags & GRE_SEQ)) {
		tpi->seq = *options;
		options++;
	} else
		tpi->seq = 0;

	/* WCCP version 1 and 2 protocol decoding.
	 * - Change protocol to IP
	 * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
	 */
	if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
		tpi->proto = htons(ETH_P_IP);
		if ((*(u8 *)options & 0xF0) != 0x40) {
			hdr_len += 4;
			if (!pskb_may_pull(skb, hdr_len))
				return -EINVAL;
		}
	}

	return iptunnel_pull_header(skb, hdr_len, tpi->proto);
}

static int gre_cisco_rcv(struct sk_buff *skb)
{
	struct tnl_ptk_info tpi;
	int i;
	bool csum_err = false;

#ifdef CONFIG_NET_IPGRE_BROADCAST
	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
		/* Looped back packet, drop it! */
		if (rt_is_output_route(skb_rtable(skb)))
			goto drop;
	}
#endif

	if (parse_gre_header(skb, &tpi, &csum_err) < 0)
		goto drop;

	rcu_read_lock();
	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
		struct gre_cisco_protocol *proto;
		int ret;

		proto = rcu_dereference(gre_cisco_proto_list[i]);
		if (!proto)
			continue;
		ret = proto->handler(skb, &tpi);
		if (ret == PACKET_RCVD) {
			rcu_read_unlock();
			return 0;
		}
	}
	rcu_read_unlock();

	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
drop:
	kfree_skb(skb);
	return 0;
}

static void gre_cisco_err(struct sk_buff *skb, u32 info)
{
	/* All the routers (except for Linux) return only
	 * 8 bytes of packet payload. It means, that precise relaying of
	 * ICMP in the real Internet is absolutely infeasible.
	 *
	 * Moreover, Cisco "wise men" put GRE key to the third word
	 * in GRE header. It makes impossible maintaining even soft
	 * state for keyed
	 * GRE tunnels with enabled checksum. Tell them "thank you".
	 *
	 * Well, I wonder, rfc1812 was written by Cisco employee,
	 * what the hell these idiots break standards established
	 * by themselves???
	 */

	const int type = icmp_hdr(skb)->type;
	const int code = icmp_hdr(skb)->code;
	struct tnl_ptk_info tpi;
	bool csum_err = false;
	int i;

	if (parse_gre_header(skb, &tpi, &csum_err)) {
		if (!csum_err)		/* ignore csum errors. */
			return;
	}

	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
		ipv4_update_pmtu(skb, dev_net(skb->dev), info,
				skb->dev->ifindex, 0, IPPROTO_GRE, 0);
		return;
	}
	if (type == ICMP_REDIRECT) {
		ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
				IPPROTO_GRE, 0);
		return;
	}

	rcu_read_lock();
	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
		struct gre_cisco_protocol *proto;

		proto = rcu_dereference(gre_cisco_proto_list[i]);
		if (!proto)
			continue;

		if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
			goto out;

	}
out:
	rcu_read_unlock();
}

static int gre_rcv(struct sk_buff *skb)
{
	const struct gre_protocol *proto;
	u8 ver;
	int ret;

	if (!pskb_may_pull(skb, 12))
		goto drop;

	ver = skb->data[1]&0x7f;
	if (ver >= GREPROTO_MAX)
		goto drop;

	rcu_read_lock();
	proto = rcu_dereference(gre_proto[ver]);
	if (!proto || !proto->handler)
		goto drop_unlock;
	ret = proto->handler(skb);
	rcu_read_unlock();
	return ret;

drop_unlock:
	rcu_read_unlock();
drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

static void gre_err(struct sk_buff *skb, u32 info)
{
	const struct gre_protocol *proto;
	const struct iphdr *iph = (const struct iphdr *)skb->data;
	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;

	if (ver >= GREPROTO_MAX)
		return;

	rcu_read_lock();
	proto = rcu_dereference(gre_proto[ver]);
	if (proto && proto->err_handler)
		proto->err_handler(skb, info);
	rcu_read_unlock();
}

static const struct net_protocol net_gre_protocol = {
	.handler     = gre_rcv,
	.err_handler = gre_err,
	.netns_ok    = 1,
};

static const struct gre_protocol ipgre_protocol = {
	.handler     = gre_cisco_rcv,
	.err_handler = gre_cisco_err,
};

int gre_cisco_register(struct gre_cisco_protocol *newp)
{
	struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
					    &gre_cisco_proto_list[newp->priority];

	return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(gre_cisco_register);

int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
{
	struct gre_cisco_protocol **proto = (struct gre_cisco_protocol **)
					    &gre_cisco_proto_list[del_proto->priority];
	int ret;

	ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;

	if (ret)
		return ret;

	synchronize_net();
	return 0;
}
EXPORT_SYMBOL_GPL(gre_cisco_unregister);

static int __init gre_init(void)
{
	pr_info("GRE over IPv4 demultiplexor driver\n");

	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
		pr_err("can't add protocol\n");
		goto err;
	}

	if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
		pr_info("%s: can't add ipgre handler\n", __func__);
		goto err_gre;
	}

	return 0;
err_gre:
	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
err:
	return -EAGAIN;
}

static void __exit gre_exit(void)
{
	gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
}

module_init(gre_init);
module_exit(gre_exit);

MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
MODULE_LICENSE("GPL");
Commit	Line	Data
00959ade DK	1	/*
	2	* GRE over IPv4 demultiplexer driver
	3	*
	4	* Authors: Dmitry Kozlov (xeb@mail.ru)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*
	11	*/
	12
afd46503 JP	13	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
afd46503 JP	14
00959ade	15	#include <linux/module.h>
bda7bb46 PS	16	#include <linux/if.h>
bda7bb46 PS	17	#include <linux/icmp.h>
00959ade DK	18	#include <linux/kernel.h>
	19	#include <linux/kmod.h>
	20	#include <linux/skbuff.h>
	21	#include <linux/in.h>
559fafb9	22	#include <linux/ip.h>
00959ade	23	#include <linux/netdevice.h>
68c33163	24	#include <linux/if_tunnel.h>
00959ade DK	25	#include <linux/spinlock.h>
	26	#include <net/protocol.h>
	27	#include <net/gre.h>
	28
bda7bb46 PS	29	#include <net/icmp.h>
	30	#include <net/route.h>
	31	#include <net/xfrm.h>
00959ade	32
6f0bcf15	33	static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
bda7bb46	34	static struct gre_cisco_protocol __rcu *gre_cisco_proto_list[GRE_IP_PROTO_MAX];
00959ade DK	35
	36	int gre_add_protocol(const struct gre_protocol *proto, u8 version)
	37	{
	38	if (version >= GREPROTO_MAX)
20fd4d1f	39	return -EINVAL;
00959ade	40
20fd4d1f PS	41	return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
20fd4d1f PS	42	0 : -EBUSY;
00959ade DK	43	}
	44	EXPORT_SYMBOL_GPL(gre_add_protocol);
	45
	46	int gre_del_protocol(const struct gre_protocol *proto, u8 version)
	47	{
20fd4d1f PS	48	int ret;
20fd4d1f PS	49
00959ade	50	if (version >= GREPROTO_MAX)
20fd4d1f PS	51	return -EINVAL;
	52
	53	ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
	54	0 : -EBUSY;
	55
	56	if (ret)
	57	return ret;
	58
00959ade DK	59	synchronize_rcu();
00959ade DK	60	return 0;
00959ade DK	61	}
	62	EXPORT_SYMBOL_GPL(gre_del_protocol);
	63
752f36da PS	64	void gre_build_header(struct sk_buff skb, const struct tnl_ptk_info tpi,
	65	int hdr_len)
	66	{
	67	struct gre_base_hdr *greh;
	68
	69	skb_push(skb, hdr_len);
	70
d0a7ebbc	71	skb_reset_transport_header(skb);
752f36da PS	72	greh = (struct gre_base_hdr *)skb->data;
	73	greh->flags = tnl_flags_to_gre_flags(tpi->flags);
	74	greh->protocol = tpi->proto;
	75
	76	if (tpi->flags&(TUNNEL_KEY\|TUNNEL_CSUM\|TUNNEL_SEQ)) {
	77	__be32 ptr = (__be32 )(((u8 *)greh) + hdr_len - 4);
	78
	79	if (tpi->flags&TUNNEL_SEQ) {
	80	*ptr = tpi->seq;
	81	ptr--;
	82	}
	83	if (tpi->flags&TUNNEL_KEY) {
	84	*ptr = tpi->key;
	85	ptr--;
	86	}
	87	if (tpi->flags&TUNNEL_CSUM &&
4749c09c TH	88	!(skb_shinfo(skb)->gso_type &
4749c09c TH	89	(SKB_GSO_GRE\|SKB_GSO_GRE_CSUM))) {
752f36da PS	90	*ptr = 0;
	91	(__sum16 )ptr = csum_fold(skb_checksum(skb, 0,
	92	skb->len, 0));
	93	}
	94	}
	95	}
	96	EXPORT_SYMBOL_GPL(gre_build_header);
	97
bda7bb46 PS	98	static int parse_gre_header(struct sk_buff skb, struct tnl_ptk_info tpi,
	99	bool *csum_err)
	100	{
bda7bb46 PS	101	const struct gre_base_hdr *greh;
	102	__be32 *options;
	103	int hdr_len;
	104
	105	if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
	106	return -EINVAL;
	107
1e701f16	108	greh = (struct gre_base_hdr *)skb_transport_header(skb);
bda7bb46 PS	109	if (unlikely(greh->flags & (GRE_VERSION \| GRE_ROUTING)))
	110	return -EINVAL;
	111
	112	tpi->flags = gre_flags_to_tnl_flags(greh->flags);
	113	hdr_len = ip_gre_calc_hlen(tpi->flags);
	114
	115	if (!pskb_may_pull(skb, hdr_len))
	116	return -EINVAL;
	117
1e701f16	118	greh = (struct gre_base_hdr *)skb_transport_header(skb);
bda7bb46 PS	119	tpi->proto = greh->protocol;
	120
	121	options = (__be32 *)(greh + 1);
	122	if (greh->flags & GRE_CSUM) {
b1036c6a	123	if (skb_checksum_simple_validate(skb)) {
bda7bb46 PS	124	*csum_err = true;
	125	return -EINVAL;
	126	}
884d338c TH	127
	128	skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
	129	null_compute_pseudo);
	130
bda7bb46 PS	131	options++;
	132	}
	133
	134	if (greh->flags & GRE_KEY) {
	135	tpi->key = *options;
	136	options++;
	137	} else
	138	tpi->key = 0;
	139
	140	if (unlikely(greh->flags & GRE_SEQ)) {
	141	tpi->seq = *options;
	142	options++;
	143	} else
	144	tpi->seq = 0;
	145
	146	/* WCCP version 1 and 2 protocol decoding.
	147	* - Change protocol to IP
	148	* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
	149	*/
	150	if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
	151	tpi->proto = htons(ETH_P_IP);
	152	if (((u8 )options & 0xF0) != 0x40) {
	153	hdr_len += 4;
	154	if (!pskb_may_pull(skb, hdr_len))
	155	return -EINVAL;
	156	}
	157	}
3d7b46cd PS	158
3d7b46cd PS	159	return iptunnel_pull_header(skb, hdr_len, tpi->proto);
bda7bb46 PS	160	}
	161
	162	static int gre_cisco_rcv(struct sk_buff *skb)
	163	{
	164	struct tnl_ptk_info tpi;
	165	int i;
	166	bool csum_err = false;
	167
fbd02dd4 PS	168	#ifdef CONFIG_NET_IPGRE_BROADCAST
	169	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
	170	/* Looped back packet, drop it! */
	171	if (rt_is_output_route(skb_rtable(skb)))
	172	goto drop;
	173	}
	174	#endif
	175
bda7bb46 PS	176	if (parse_gre_header(skb, &tpi, &csum_err) < 0)
	177	goto drop;
	178
	179	rcu_read_lock();
	180	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
	181	struct gre_cisco_protocol *proto;
	182	int ret;
	183
	184	proto = rcu_dereference(gre_cisco_proto_list[i]);
	185	if (!proto)
	186	continue;
	187	ret = proto->handler(skb, &tpi);
	188	if (ret == PACKET_RCVD) {
	189	rcu_read_unlock();
	190	return 0;
	191	}
	192	}
	193	rcu_read_unlock();
	194
	195	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
	196	drop:
	197	kfree_skb(skb);
	198	return 0;
	199	}
	200
	201	static void gre_cisco_err(struct sk_buff *skb, u32 info)
	202	{
	203	/* All the routers (except for Linux) return only
	204	* 8 bytes of packet payload. It means, that precise relaying of
	205	* ICMP in the real Internet is absolutely infeasible.
	206	*
	207	* Moreover, Cisco "wise men" put GRE key to the third word
	208	* in GRE header. It makes impossible maintaining even soft
	209	* state for keyed
	210	* GRE tunnels with enabled checksum. Tell them "thank you".
	211	*
	212	* Well, I wonder, rfc1812 was written by Cisco employee,
	213	* what the hell these idiots break standards established
	214	* by themselves???
	215	*/
	216
	217	const int type = icmp_hdr(skb)->type;
	218	const int code = icmp_hdr(skb)->code;
	219	struct tnl_ptk_info tpi;
	220	bool csum_err = false;
	221	int i;
	222
	223	if (parse_gre_header(skb, &tpi, &csum_err)) {
	224	if (!csum_err) /* ignore csum errors. */
	225	return;
	226	}
	227
	228	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
	229	ipv4_update_pmtu(skb, dev_net(skb->dev), info,
	230	skb->dev->ifindex, 0, IPPROTO_GRE, 0);
	231	return;
	232	}
	233	if (type == ICMP_REDIRECT) {
	234	ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
	235	IPPROTO_GRE, 0);
	236	return;
	237	}
	238
	239	rcu_read_lock();
240	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
241	struct gre_cisco_protocol *proto;
242
243	proto = rcu_dereference(gre_cisco_proto_list[i]);
244	if (!proto)
245	continue;
246
247	if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
248	goto out;
249
250	}
251	out:
252	rcu_read_unlock();
253	}
254
00959ade DK	255	static int gre_rcv(struct sk_buff *skb)
	256	{
	257	const struct gre_protocol *proto;
	258	u8 ver;
	259	int ret;
	260
	261	if (!pskb_may_pull(skb, 12))
	262	goto drop;
	263
	264	ver = skb->data[1]&0x7f;
	265	if (ver >= GREPROTO_MAX)
	266	goto drop;
	267
	268	rcu_read_lock();
	269	proto = rcu_dereference(gre_proto[ver]);
	270	if (!proto \|\| !proto->handler)
	271	goto drop_unlock;
	272	ret = proto->handler(skb);
	273	rcu_read_unlock();
	274	return ret;
	275
	276	drop_unlock:
	277	rcu_read_unlock();
	278	drop:
	279	kfree_skb(skb);
	280	return NET_RX_DROP;
	281	}
	282
	283	static void gre_err(struct sk_buff *skb, u32 info)
	284	{
	285	const struct gre_protocol *proto;
559fafb9	286	const struct iphdr iph = (const struct iphdr )skb->data;
559fafb9	287	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
00959ade	288
00959ade	289	if (ver >= GREPROTO_MAX)
559fafb9	290	return;
00959ade DK	291
	292	rcu_read_lock();
	293	proto = rcu_dereference(gre_proto[ver]);
559fafb9	294	if (proto && proto->err_handler)
559fafb9	295	proto->err_handler(skb, info);
00959ade	296	rcu_read_unlock();
00959ade DK	297	}
	298
	299	static const struct net_protocol net_gre_protocol = {
	300	.handler = gre_rcv,
	301	.err_handler = gre_err,
	302	.netns_ok = 1,
	303	};
	304
bda7bb46 PS	305	static const struct gre_protocol ipgre_protocol = {
	306	.handler = gre_cisco_rcv,
	307	.err_handler = gre_cisco_err,
	308	};
	309
	310	int gre_cisco_register(struct gre_cisco_protocol *newp)
	311	{
	312	struct gre_cisco_protocol proto = (struct gre_cisco_protocol )
	313	&gre_cisco_proto_list[newp->priority];
	314
	315	return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
	316	}
	317	EXPORT_SYMBOL_GPL(gre_cisco_register);
	318
	319	int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
	320	{
	321	struct gre_cisco_protocol proto = (struct gre_cisco_protocol )
	322	&gre_cisco_proto_list[del_proto->priority];
	323	int ret;
	324
	325	ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;
	326
	327	if (ret)
	328	return ret;
	329
	330	synchronize_net();
	331	return 0;
	332	}
	333	EXPORT_SYMBOL_GPL(gre_cisco_unregister);
	334
00959ade DK	335	static int __init gre_init(void)
00959ade DK	336	{
afd46503	337	pr_info("GRE over IPv4 demultiplexor driver\n");
00959ade DK	338
00959ade DK	339	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
afd46503	340	pr_err("can't add protocol\n");
bda7bb46 PS	341	goto err;
	342	}
	343
	344	if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
	345	pr_info("%s: can't add ipgre handler\n", __func__);
	346	goto err_gre;
00959ade DK	347	}
	348
	349	return 0;
bda7bb46 PS	350	err_gre:
	351	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	352	err:
	353	return -EAGAIN;
00959ade DK	354	}
	355
	356	static void __exit gre_exit(void)
	357	{
bda7bb46	358	gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
00959ade DK	359	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	360	}
	361
	362	module_init(gre_init);
	363	module_exit(gre_exit);
	364
	365	MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
	366	MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
	367	MODULE_LICENSE("GPL");