[mirror_ubuntu-bionic-kernel.git] / net / ipv4 / gre.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/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>


static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
static DEFINE_SPINLOCK(gre_proto_lock);
struct gre_base_hdr {
	__be16 flags;
	__be16 protocol;
};
#define GRE_HEADER_SECTION 4

int gre_add_protocol(const struct gre_protocol *proto, u8 version)
{
	if (version >= GREPROTO_MAX)
		goto err_out;

	spin_lock(&gre_proto_lock);
	if (gre_proto[version])
		goto err_out_unlock;

	RCU_INIT_POINTER(gre_proto[version], proto);
	spin_unlock(&gre_proto_lock);
	return 0;

err_out_unlock:
	spin_unlock(&gre_proto_lock);
err_out:
	return -1;
}
EXPORT_SYMBOL_GPL(gre_add_protocol);

int gre_del_protocol(const struct gre_protocol *proto, u8 version)
{
	if (version >= GREPROTO_MAX)
		goto err_out;

	spin_lock(&gre_proto_lock);
	if (rcu_dereference_protected(gre_proto[version],
			lockdep_is_held(&gre_proto_lock)) != proto)
		goto err_out_unlock;
	RCU_INIT_POINTER(gre_proto[version], NULL);
	spin_unlock(&gre_proto_lock);
	synchronize_rcu();
	return 0;

err_out_unlock:
	spin_unlock(&gre_proto_lock);
err_out:
	return -1;
}
EXPORT_SYMBOL_GPL(gre_del_protocol);

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 struct sk_buff *gre_gso_segment(struct sk_buff *skb,
				       netdev_features_t features)
{
	struct sk_buff *segs = ERR_PTR(-EINVAL);
	netdev_features_t enc_features;
	int ghl = GRE_HEADER_SECTION;
	struct gre_base_hdr *greh;
	int mac_len = skb->mac_len;
	int tnl_hlen;
	bool csum;

	if (unlikely(skb_shinfo(skb)->gso_type &
				~(SKB_GSO_TCPV4 |
				  SKB_GSO_TCPV6 |
				  SKB_GSO_UDP |
				  SKB_GSO_DODGY |
				  SKB_GSO_TCP_ECN |
				  SKB_GSO_GRE)))
		goto out;

	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
		goto out;

	greh = (struct gre_base_hdr *)skb_transport_header(skb);

	if (greh->flags & GRE_KEY)
		ghl += GRE_HEADER_SECTION;
	if (greh->flags & GRE_SEQ)
		ghl += GRE_HEADER_SECTION;
	if (greh->flags & GRE_CSUM) {
		ghl += GRE_HEADER_SECTION;
		csum = true;
	} else
		csum = false;

	/* setup inner skb. */
	if (greh->protocol == htons(ETH_P_TEB)) {
		struct ethhdr *eth = eth_hdr(skb);
		skb->protocol = eth->h_proto;
	} else {
		skb->protocol = greh->protocol;
	}

	skb->encapsulation = 0;

	if (unlikely(!pskb_may_pull(skb, ghl)))
		goto out;
	__skb_pull(skb, ghl);
	skb_reset_mac_header(skb);
	skb_set_network_header(skb, skb_inner_network_offset(skb));
	skb->mac_len = skb_inner_network_offset(skb);

	/* segment inner packet. */
	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
	segs = skb_mac_gso_segment(skb, enc_features);
	if (!segs || IS_ERR(segs))
		goto out;

	skb = segs;
	tnl_hlen = skb_tnl_header_len(skb);
	do {
		__skb_push(skb, ghl);
		if (csum) {
			__be32 *pcsum;

			if (skb_has_shared_frag(skb)) {
				int err;

				err = __skb_linearize(skb);
				if (err) {
					kfree_skb(segs);
					segs = ERR_PTR(err);
					goto out;
				}
			}

			greh = (struct gre_base_hdr *)(skb->data);
			pcsum = (__be32 *)(greh + 1);
			*pcsum = 0;
			*(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
		}
		__skb_push(skb, tnl_hlen - ghl);

		skb_reset_mac_header(skb);
		skb_set_network_header(skb, mac_len);
		skb->mac_len = mac_len;
	} while ((skb = skb->next));
out:
	return segs;
}

static int gre_gso_send_check(struct sk_buff *skb)
{
	if (!skb->encapsulation)
		return -EINVAL;
	return 0;
}

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

static const struct net_offload gre_offload = {
	.callbacks = {
		.gso_send_check =	gre_gso_send_check,
		.gso_segment    =	gre_gso_segment,
	},
};

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;
	}

	if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
		pr_err("can't add protocol offload\n");
		inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
		return -EAGAIN;
	}

	return 0;
}

static void __exit gre_exit(void)
{
	inet_del_offload(&gre_offload, IPPROTO_GRE);
	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 DK	15	#include <linux/module.h>
	16	#include <linux/kernel.h>
	17	#include <linux/kmod.h>
	18	#include <linux/skbuff.h>
	19	#include <linux/in.h>
559fafb9	20	#include <linux/ip.h>
00959ade	21	#include <linux/netdevice.h>
68c33163	22	#include <linux/if_tunnel.h>
00959ade DK	23	#include <linux/spinlock.h>
	24	#include <net/protocol.h>
	25	#include <net/gre.h>
	26
	27
6f0bcf15	28	static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
00959ade	29	static DEFINE_SPINLOCK(gre_proto_lock);
68c33163 PS	30	struct gre_base_hdr {
	31	__be16 flags;
	32	__be16 protocol;
	33	};
	34	#define GRE_HEADER_SECTION 4
00959ade DK	35
	36	int gre_add_protocol(const struct gre_protocol *proto, u8 version)
	37	{
	38	if (version >= GREPROTO_MAX)
	39	goto err_out;
	40
	41	spin_lock(&gre_proto_lock);
	42	if (gre_proto[version])
	43	goto err_out_unlock;
	44
a9b3cd7f	45	RCU_INIT_POINTER(gre_proto[version], proto);
00959ade DK	46	spin_unlock(&gre_proto_lock);
	47	return 0;
	48
	49	err_out_unlock:
	50	spin_unlock(&gre_proto_lock);
	51	err_out:
	52	return -1;
	53	}
	54	EXPORT_SYMBOL_GPL(gre_add_protocol);
	55
	56	int gre_del_protocol(const struct gre_protocol *proto, u8 version)
	57	{
	58	if (version >= GREPROTO_MAX)
	59	goto err_out;
	60
	61	spin_lock(&gre_proto_lock);
6f0bcf15 ED	62	if (rcu_dereference_protected(gre_proto[version],
6f0bcf15 ED	63	lockdep_is_held(&gre_proto_lock)) != proto)
00959ade	64	goto err_out_unlock;
a9b3cd7f	65	RCU_INIT_POINTER(gre_proto[version], NULL);
00959ade DK	66	spin_unlock(&gre_proto_lock);
	67	synchronize_rcu();
	68	return 0;
	69
	70	err_out_unlock:
	71	spin_unlock(&gre_proto_lock);
	72	err_out:
	73	return -1;
	74	}
	75	EXPORT_SYMBOL_GPL(gre_del_protocol);
	76
	77	static int gre_rcv(struct sk_buff *skb)
	78	{
	79	const struct gre_protocol *proto;
	80	u8 ver;
	81	int ret;
	82
	83	if (!pskb_may_pull(skb, 12))
	84	goto drop;
	85
	86	ver = skb->data[1]&0x7f;
	87	if (ver >= GREPROTO_MAX)
	88	goto drop;
	89
	90	rcu_read_lock();
	91	proto = rcu_dereference(gre_proto[ver]);
	92	if (!proto \|\| !proto->handler)
	93	goto drop_unlock;
	94	ret = proto->handler(skb);
	95	rcu_read_unlock();
	96	return ret;
	97
	98	drop_unlock:
	99	rcu_read_unlock();
	100	drop:
	101	kfree_skb(skb);
	102	return NET_RX_DROP;
	103	}
	104
	105	static void gre_err(struct sk_buff *skb, u32 info)
	106	{
	107	const struct gre_protocol *proto;
559fafb9	108	const struct iphdr iph = (const struct iphdr )skb->data;
559fafb9	109	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
00959ade	110
00959ade	111	if (ver >= GREPROTO_MAX)
559fafb9	112	return;
00959ade DK	113
	114	rcu_read_lock();
	115	proto = rcu_dereference(gre_proto[ver]);
559fafb9	116	if (proto && proto->err_handler)
559fafb9	117	proto->err_handler(skb, info);
00959ade	118	rcu_read_unlock();
00959ade DK	119	}
00959ade DK	120
68c33163 PS	121	static struct sk_buff gre_gso_segment(struct sk_buff skb,
	122	netdev_features_t features)
	123	{
	124	struct sk_buff *segs = ERR_PTR(-EINVAL);
	125	netdev_features_t enc_features;
	126	int ghl = GRE_HEADER_SECTION;
	127	struct gre_base_hdr *greh;
	128	int mac_len = skb->mac_len;
	129	int tnl_hlen;
	130	bool csum;
	131
	132	if (unlikely(skb_shinfo(skb)->gso_type &
	133	~(SKB_GSO_TCPV4 \|
	134	SKB_GSO_TCPV6 \|
	135	SKB_GSO_UDP \|
	136	SKB_GSO_DODGY \|
	137	SKB_GSO_TCP_ECN \|
	138	SKB_GSO_GRE)))
	139	goto out;
	140
	141	if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
	142	goto out;
	143
	144	greh = (struct gre_base_hdr *)skb_transport_header(skb);
	145
	146	if (greh->flags & GRE_KEY)
	147	ghl += GRE_HEADER_SECTION;
	148	if (greh->flags & GRE_SEQ)
	149	ghl += GRE_HEADER_SECTION;
	150	if (greh->flags & GRE_CSUM) {
	151	ghl += GRE_HEADER_SECTION;
	152	csum = true;
	153	} else
	154	csum = false;
	155
	156	/* setup inner skb. */
	157	if (greh->protocol == htons(ETH_P_TEB)) {
	158	struct ethhdr *eth = eth_hdr(skb);
	159	skb->protocol = eth->h_proto;
	160	} else {
	161	skb->protocol = greh->protocol;
	162	}
	163
	164	skb->encapsulation = 0;
	165
	166	if (unlikely(!pskb_may_pull(skb, ghl)))
	167	goto out;
	168	__skb_pull(skb, ghl);
	169	skb_reset_mac_header(skb);
	170	skb_set_network_header(skb, skb_inner_network_offset(skb));
	171	skb->mac_len = skb_inner_network_offset(skb);
	172
	173	/* segment inner packet. */
	174	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
	175	segs = skb_mac_gso_segment(skb, enc_features);
	176	if (!segs \|\| IS_ERR(segs))
	177	goto out;
	178
	179	skb = segs;
	180	tnl_hlen = skb_tnl_header_len(skb);
	181	do {
	182	__skb_push(skb, ghl);
	183	if (csum) {
	184	__be32 *pcsum;
185
186	if (skb_has_shared_frag(skb)) {
187	int err;
188
189	err = __skb_linearize(skb);
190	if (err) {
191	kfree_skb(segs);
192	segs = ERR_PTR(err);
193	goto out;
194	}
195	}
196
197	greh = (struct gre_base_hdr *)(skb->data);
198	pcsum = (__be32 *)(greh + 1);
199	*pcsum = 0;
200	(__sum16 )pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
201	}
202	__skb_push(skb, tnl_hlen - ghl);
203
204	skb_reset_mac_header(skb);
205	skb_set_network_header(skb, mac_len);
206	skb->mac_len = mac_len;
207	} while ((skb = skb->next));
208	out:
209	return segs;
210	}
211
212	static int gre_gso_send_check(struct sk_buff *skb)
213	{
214	if (!skb->encapsulation)
215	return -EINVAL;
216	return 0;
217	}
218
00959ade DK	219	static const struct net_protocol net_gre_protocol = {
	220	.handler = gre_rcv,
	221	.err_handler = gre_err,
	222	.netns_ok = 1,
	223	};
	224
68c33163 PS	225	static const struct net_offload gre_offload = {
	226	.callbacks = {
	227	.gso_send_check = gre_gso_send_check,
	228	.gso_segment = gre_gso_segment,
	229	},
	230	};
	231
00959ade DK	232	static int __init gre_init(void)
00959ade DK	233	{
afd46503	234	pr_info("GRE over IPv4 demultiplexor driver\n");
00959ade DK	235
00959ade DK	236	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
afd46503	237	pr_err("can't add protocol\n");
00959ade DK	238	return -EAGAIN;
	239	}
	240
68c33163 PS	241	if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
	242	pr_err("can't add protocol offload\n");
	243	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	244	return -EAGAIN;
	245	}
	246
00959ade DK	247	return 0;
	248	}
	249
	250	static void __exit gre_exit(void)
	251	{
68c33163	252	inet_del_offload(&gre_offload, IPPROTO_GRE);
00959ade DK	253	inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
	254	}
	255
	256	module_init(gre_init);
	257	module_exit(gre_exit);
	258
	259	MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
	260	MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
	261	MODULE_LICENSE("GPL");
	262