[mirror_ubuntu-artful-kernel.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);

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
bda7bb46 PS	64	static int parse_gre_header(struct sk_buff skb, struct tnl_ptk_info tpi,
	65	bool *csum_err)
	66	{
bda7bb46 PS	67	const struct gre_base_hdr *greh;
	68	__be32 *options;
	69	int hdr_len;
	70
	71	if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
	72	return -EINVAL;
	73
1e701f16	74	greh = (struct gre_base_hdr *)skb_transport_header(skb);
bda7bb46 PS	75	if (unlikely(greh->flags & (GRE_VERSION \| GRE_ROUTING)))
	76	return -EINVAL;
	77
	78	tpi->flags = gre_flags_to_tnl_flags(greh->flags);
	79	hdr_len = ip_gre_calc_hlen(tpi->flags);
	80
	81	if (!pskb_may_pull(skb, hdr_len))
	82	return -EINVAL;
	83
1e701f16	84	greh = (struct gre_base_hdr *)skb_transport_header(skb);
bda7bb46 PS	85	tpi->proto = greh->protocol;
	86
	87	options = (__be32 *)(greh + 1);
	88	if (greh->flags & GRE_CSUM) {
b1036c6a	89	if (skb_checksum_simple_validate(skb)) {
bda7bb46 PS	90	*csum_err = true;
	91	return -EINVAL;
	92	}
884d338c TH	93
	94	skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
	95	null_compute_pseudo);
	96
bda7bb46 PS	97	options++;
	98	}
	99
	100	if (greh->flags & GRE_KEY) {
	101	tpi->key = *options;
	102	options++;
	103	} else
	104	tpi->key = 0;
	105
	106	if (unlikely(greh->flags & GRE_SEQ)) {
	107	tpi->seq = *options;
	108	options++;
	109	} else
	110	tpi->seq = 0;
	111
	112	/* WCCP version 1 and 2 protocol decoding.
	113	* - Change protocol to IP
	114	* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
	115	*/
	116	if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
	117	tpi->proto = htons(ETH_P_IP);
	118	if (((u8 )options & 0xF0) != 0x40) {
	119	hdr_len += 4;
	120	if (!pskb_may_pull(skb, hdr_len))
	121	return -EINVAL;
	122	}
	123	}
3d7b46cd PS	124
3d7b46cd PS	125	return iptunnel_pull_header(skb, hdr_len, tpi->proto);
bda7bb46 PS	126	}
	127
	128	static int gre_cisco_rcv(struct sk_buff *skb)
	129	{
	130	struct tnl_ptk_info tpi;
	131	int i;
	132	bool csum_err = false;
	133
fbd02dd4 PS	134	#ifdef CONFIG_NET_IPGRE_BROADCAST
	135	if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
	136	/* Looped back packet, drop it! */
	137	if (rt_is_output_route(skb_rtable(skb)))
	138	goto drop;
	139	}
	140	#endif
	141
bda7bb46 PS	142	if (parse_gre_header(skb, &tpi, &csum_err) < 0)
	143	goto drop;
	144
	145	rcu_read_lock();
	146	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
	147	struct gre_cisco_protocol *proto;
	148	int ret;
	149
	150	proto = rcu_dereference(gre_cisco_proto_list[i]);
	151	if (!proto)
	152	continue;
	153	ret = proto->handler(skb, &tpi);
	154	if (ret == PACKET_RCVD) {
	155	rcu_read_unlock();
	156	return 0;
	157	}
	158	}
	159	rcu_read_unlock();
	160
	161	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
	162	drop:
	163	kfree_skb(skb);
	164	return 0;
	165	}
	166
	167	static void gre_cisco_err(struct sk_buff *skb, u32 info)
	168	{
	169	/* All the routers (except for Linux) return only
	170	* 8 bytes of packet payload. It means, that precise relaying of
	171	* ICMP in the real Internet is absolutely infeasible.
	172	*
	173	* Moreover, Cisco "wise men" put GRE key to the third word
	174	* in GRE header. It makes impossible maintaining even soft
	175	* state for keyed
	176	* GRE tunnels with enabled checksum. Tell them "thank you".
	177	*
	178	* Well, I wonder, rfc1812 was written by Cisco employee,
	179	* what the hell these idiots break standards established
	180	* by themselves???
	181	*/
	182
	183	const int type = icmp_hdr(skb)->type;
	184	const int code = icmp_hdr(skb)->code;
	185	struct tnl_ptk_info tpi;
	186	bool csum_err = false;
	187	int i;
	188
	189	if (parse_gre_header(skb, &tpi, &csum_err)) {
	190	if (!csum_err) /* ignore csum errors. */
	191	return;
	192	}
	193
	194	if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
	195	ipv4_update_pmtu(skb, dev_net(skb->dev), info,
	196	skb->dev->ifindex, 0, IPPROTO_GRE, 0);
	197	return;
	198	}
	199	if (type == ICMP_REDIRECT) {
	200	ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex, 0,
	201	IPPROTO_GRE, 0);
	202	return;
	203	}
	204
	205	rcu_read_lock();
206	for (i = 0; i < GRE_IP_PROTO_MAX; i++) {
207	struct gre_cisco_protocol *proto;
208
209	proto = rcu_dereference(gre_cisco_proto_list[i]);
210	if (!proto)
211	continue;
212
213	if (proto->err_handler(skb, info, &tpi) == PACKET_RCVD)
214	goto out;
215
216	}
217	out:
218	rcu_read_unlock();
219	}
220
00959ade DK	221	static int gre_rcv(struct sk_buff *skb)
	222	{
	223	const struct gre_protocol *proto;
	224	u8 ver;
	225	int ret;
	226
	227	if (!pskb_may_pull(skb, 12))
	228	goto drop;
	229
	230	ver = skb->data[1]&0x7f;
	231	if (ver >= GREPROTO_MAX)
	232	goto drop;
	233
	234	rcu_read_lock();
	235	proto = rcu_dereference(gre_proto[ver]);
	236	if (!proto \|\| !proto->handler)
	237	goto drop_unlock;
	238	ret = proto->handler(skb);
	239	rcu_read_unlock();
	240	return ret;
	241
	242	drop_unlock:
	243	rcu_read_unlock();
	244	drop:
	245	kfree_skb(skb);
	246	return NET_RX_DROP;
	247	}
	248
	249	static void gre_err(struct sk_buff *skb, u32 info)
	250	{
	251	const struct gre_protocol *proto;
559fafb9	252	const struct iphdr iph = (const struct iphdr )skb->data;
559fafb9	253	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
00959ade	254
00959ade	255	if (ver >= GREPROTO_MAX)
559fafb9	256	return;
00959ade DK	257
	258	rcu_read_lock();
	259	proto = rcu_dereference(gre_proto[ver]);
559fafb9	260	if (proto && proto->err_handler)
559fafb9	261	proto->err_handler(skb, info);
00959ade	262	rcu_read_unlock();
00959ade DK	263	}
	264
	265	static const struct net_protocol net_gre_protocol = {
	266	.handler = gre_rcv,
	267	.err_handler = gre_err,
	268	.netns_ok = 1,
	269	};
	270
bda7bb46 PS	271	static const struct gre_protocol ipgre_protocol = {
	272	.handler = gre_cisco_rcv,
	273	.err_handler = gre_cisco_err,
	274	};
	275
	276	int gre_cisco_register(struct gre_cisco_protocol *newp)
	277	{
	278	struct gre_cisco_protocol proto = (struct gre_cisco_protocol )
	279	&gre_cisco_proto_list[newp->priority];
	280
	281	return (cmpxchg(proto, NULL, newp) == NULL) ? 0 : -EBUSY;
	282	}
	283	EXPORT_SYMBOL_GPL(gre_cisco_register);
	284
	285	int gre_cisco_unregister(struct gre_cisco_protocol *del_proto)
	286	{
	287	struct gre_cisco_protocol proto = (struct gre_cisco_protocol )
	288	&gre_cisco_proto_list[del_proto->priority];
	289	int ret;
	290
	291	ret = (cmpxchg(proto, del_proto, NULL) == del_proto) ? 0 : -EINVAL;
	292
	293	if (ret)
	294	return ret;
	295
	296	synchronize_net();
	297	return 0;
	298	}
	299	EXPORT_SYMBOL_GPL(gre_cisco_unregister);
	300
00959ade DK	301	static int __init gre_init(void)
00959ade DK	302	{
afd46503	303	pr_info("GRE over IPv4 demultiplexor driver\n");
00959ade DK	304
00959ade DK	305	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
afd46503	306	pr_err("can't add protocol\n");
bda7bb46 PS	307	goto err;
	308	}
	309
	310	if (gre_add_protocol(&ipgre_protocol, GREPROTO_CISCO) < 0) {
	311	pr_info("%s: can't add ipgre handler\n", __func__);
	312	goto err_gre;
00959ade DK	313	}
	314
	315	return 0;
bda7bb46 PS	316	err_gre:
	317	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	318	err:
	319	return -EAGAIN;
00959ade DK	320	}
	321
	322	static void __exit gre_exit(void)
	323	{
bda7bb46	324	gre_del_protocol(&ipgre_protocol, GREPROTO_CISCO);
00959ade DK	325	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	326	}
	327
	328	module_init(gre_init);
	329	module_exit(gre_exit);
	330
	331	MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
	332	MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
	333	MODULE_LICENSE("GPL");