[mirror_ubuntu-bionic-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;

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);

int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
		     bool *csum_err, int *ret_hdr_len)
{
	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 = 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;
		}
	}
	*ret_hdr_len = hdr_len;
	return 0;
}
EXPORT_SYMBOL(gre_parse_header);

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 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");
		return -EAGAIN;
	}
	return 0;
}

static void __exit gre_exit(void)
{
	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;
00959ade DK	34
	35	int gre_add_protocol(const struct gre_protocol *proto, u8 version)
	36	{
	37	if (version >= GREPROTO_MAX)
20fd4d1f	38	return -EINVAL;
00959ade	39
20fd4d1f PS	40	return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ?
20fd4d1f PS	41	0 : -EBUSY;
00959ade DK	42	}
	43	EXPORT_SYMBOL_GPL(gre_add_protocol);
	44
	45	int gre_del_protocol(const struct gre_protocol *proto, u8 version)
	46	{
20fd4d1f PS	47	int ret;
20fd4d1f PS	48
00959ade	49	if (version >= GREPROTO_MAX)
20fd4d1f PS	50	return -EINVAL;
	51
	52	ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ?
	53	0 : -EBUSY;
	54
	55	if (ret)
	56	return ret;
	57
00959ade DK	58	synchronize_rcu();
00959ade DK	59	return 0;
00959ade DK	60	}
	61	EXPORT_SYMBOL_GPL(gre_del_protocol);
	62
95f5c64c TH	63	int gre_parse_header(struct sk_buff skb, struct tnl_ptk_info tpi,
	64	bool csum_err, int ret_hdr_len)
	65	{
	66	const struct gre_base_hdr *greh;
	67	__be32 *options;
	68	int hdr_len;
	69
	70	if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
	71	return -EINVAL;
	72
	73	greh = (struct gre_base_hdr *)skb_transport_header(skb);
	74	if (unlikely(greh->flags & (GRE_VERSION \| GRE_ROUTING)))
	75	return -EINVAL;
	76
	77	tpi->flags = gre_flags_to_tnl_flags(greh->flags);
	78	hdr_len = gre_calc_hlen(tpi->flags);
	79
	80	if (!pskb_may_pull(skb, hdr_len))
	81	return -EINVAL;
	82
	83	greh = (struct gre_base_hdr *)skb_transport_header(skb);
	84	tpi->proto = greh->protocol;
	85
	86	options = (__be32 *)(greh + 1);
	87	if (greh->flags & GRE_CSUM) {
	88	if (skb_checksum_simple_validate(skb)) {
	89	*csum_err = true;
	90	return -EINVAL;
	91	}
	92
	93	skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
	94	null_compute_pseudo);
	95	options++;
	96	}
	97
	98	if (greh->flags & GRE_KEY) {
	99	tpi->key = *options;
	100	options++;
	101	} else {
	102	tpi->key = 0;
	103	}
	104	if (unlikely(greh->flags & GRE_SEQ)) {
	105	tpi->seq = *options;
	106	options++;
	107	} else {
	108	tpi->seq = 0;
	109	}
	110	/* WCCP version 1 and 2 protocol decoding.
	111	* - Change protocol to IP
	112	* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
	113	*/
	114	if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
	115	tpi->proto = htons(ETH_P_IP);
	116	if (((u8 )options & 0xF0) != 0x40) {
	117	hdr_len += 4;
	118	if (!pskb_may_pull(skb, hdr_len))
	119	return -EINVAL;
	120	}
	121	}
	122	*ret_hdr_len = hdr_len;
	123	return 0;
	124	}
	125	EXPORT_SYMBOL(gre_parse_header);
	126
00959ade DK	127	static int gre_rcv(struct sk_buff *skb)
	128	{
	129	const struct gre_protocol *proto;
	130	u8 ver;
	131	int ret;
	132
	133	if (!pskb_may_pull(skb, 12))
	134	goto drop;
	135
	136	ver = skb->data[1]&0x7f;
	137	if (ver >= GREPROTO_MAX)
	138	goto drop;
	139
	140	rcu_read_lock();
	141	proto = rcu_dereference(gre_proto[ver]);
	142	if (!proto \|\| !proto->handler)
	143	goto drop_unlock;
	144	ret = proto->handler(skb);
	145	rcu_read_unlock();
	146	return ret;
	147
	148	drop_unlock:
	149	rcu_read_unlock();
	150	drop:
	151	kfree_skb(skb);
	152	return NET_RX_DROP;
	153	}
	154
	155	static void gre_err(struct sk_buff *skb, u32 info)
	156	{
	157	const struct gre_protocol *proto;
559fafb9	158	const struct iphdr iph = (const struct iphdr )skb->data;
559fafb9	159	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
00959ade	160
00959ade	161	if (ver >= GREPROTO_MAX)
559fafb9	162	return;
00959ade DK	163
	164	rcu_read_lock();
	165	proto = rcu_dereference(gre_proto[ver]);
559fafb9	166	if (proto && proto->err_handler)
559fafb9	167	proto->err_handler(skb, info);
00959ade	168	rcu_read_unlock();
00959ade DK	169	}
	170
	171	static const struct net_protocol net_gre_protocol = {
	172	.handler = gre_rcv,
	173	.err_handler = gre_err,
	174	.netns_ok = 1,
	175	};
	176
	177	static int __init gre_init(void)
	178	{
afd46503	179	pr_info("GRE over IPv4 demultiplexor driver\n");
00959ade DK	180
00959ade DK	181	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
afd46503	182	pr_err("can't add protocol\n");
9f57c67c	183	return -EAGAIN;
bda7bb46	184	}
00959ade DK	185	return 0;
	186	}
	187
	188	static void __exit gre_exit(void)
	189	{
	190	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	191	}
	192
	193	module_init(gre_init);
	194	module_exit(gre_exit);
	195
	196	MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
	197	MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
	198	MODULE_LICENSE("GPL");