1/*
2 * Copyright (c) 2007-2014 Nicira, Inc.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
16 * 02110-1301, USA
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/if.h>
22#include <linux/skbuff.h>
23#include <linux/ip.h>
24#include <linux/if_tunnel.h>
25#include <linux/if_vlan.h>
26#include <linux/in.h>
27#include <linux/in_route.h>
28#include <linux/inetdevice.h>
29#include <linux/jhash.h>
30#include <linux/list.h>
31#include <linux/kernel.h>
32#include <linux/module.h>
33#include <linux/workqueue.h>
34#include <linux/rculist.h>
35#include <net/route.h>
36#include <net/xfrm.h>
37
38#include <net/icmp.h>
39#include <net/ip.h>
40#include <net/ip_tunnels.h>
41#include <net/gre.h>
42#include <net/net_namespace.h>
43#include <net/netns/generic.h>
44#include <net/protocol.h>
45
46#include "datapath.h"
47#include "vport.h"
48
49static struct vport_ops ovs_gre_vport_ops;
50
51/* Returns the least-significant 32 bits of a __be64. */
52static __be32 be64_get_low32(__be64 x)
53{
54#ifdef __BIG_ENDIAN
55	return (__force __be32)x;
56#else
57	return (__force __be32)((__force u64)x >> 32);
58#endif
59}
60
61static __be16 filter_tnl_flags(__be16 flags)
62{
63	return flags & (TUNNEL_CSUM | TUNNEL_KEY);
64}
65
66static struct sk_buff *__build_header(struct sk_buff *skb,
67				      int tunnel_hlen)
68{
69	struct tnl_ptk_info tpi;
70	const struct ovs_key_ipv4_tunnel *tun_key;
71
72	tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
73
74	skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
75	if (IS_ERR(skb))
76		return skb;
77
78	tpi.flags = filter_tnl_flags(tun_key->tun_flags);
79	tpi.proto = htons(ETH_P_TEB);
80	tpi.key = be64_get_low32(tun_key->tun_id);
81	tpi.seq = 0;
82	gre_build_header(skb, &tpi, tunnel_hlen);
83
84	return skb;
85}
86
87static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
88{
89#ifdef __BIG_ENDIAN
90	return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
91#else
92	return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
93#endif
94}
95
96/* Called with rcu_read_lock and BH disabled. */
97static int gre_rcv(struct sk_buff *skb,
98		   const struct tnl_ptk_info *tpi)
99{
100	struct ovs_tunnel_info tun_info;
101	struct ovs_net *ovs_net;
102	struct vport *vport;
103	__be64 key;
104
105	ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
106	vport = rcu_dereference(ovs_net->vport_net.gre_vport);
107	if (unlikely(!vport))
108		return PACKET_REJECT;
109
110	key = key_to_tunnel_id(tpi->key, tpi->seq);
111	ovs_flow_tun_info_init(&tun_info, ip_hdr(skb), 0, 0, key,
112			       filter_tnl_flags(tpi->flags), NULL, 0);
113
114	ovs_vport_receive(vport, skb, &tun_info);
115	return PACKET_RCVD;
116}
117
118/* Called with rcu_read_lock and BH disabled. */
119static int gre_err(struct sk_buff *skb, u32 info,
120		   const struct tnl_ptk_info *tpi)
121{
122	struct ovs_net *ovs_net;
123	struct vport *vport;
124
125	ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
126	vport = rcu_dereference(ovs_net->vport_net.gre_vport);
127
128	if (unlikely(!vport))
129		return PACKET_REJECT;
130	else
131		return PACKET_RCVD;
132}
133
134static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
135{
136	struct net *net = ovs_dp_get_net(vport->dp);
137	const struct ovs_key_ipv4_tunnel *tun_key;
138	struct flowi4 fl;
139	struct rtable *rt;
140	int min_headroom;
141	int tunnel_hlen;
142	__be16 df;
143	int err;
144
145	if (unlikely(!OVS_CB(skb)->egress_tun_info)) {
146		err = -EINVAL;
147		goto err_free_skb;
148	}
149
150	tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
151	rt = ovs_tunnel_route_lookup(net, tun_key, skb->mark, &fl, IPPROTO_GRE);
152	if (IS_ERR(rt)) {
153		err = PTR_ERR(rt);
154		goto err_free_skb;
155	}
156
157	tunnel_hlen = ip_gre_calc_hlen(tun_key->tun_flags);
158
159	min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
160			+ tunnel_hlen + sizeof(struct iphdr)
161			+ (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
162	if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
163		int head_delta = SKB_DATA_ALIGN(min_headroom -
164						skb_headroom(skb) +
165						16);
166		err = pskb_expand_head(skb, max_t(int, head_delta, 0),
167					0, GFP_ATOMIC);
168		if (unlikely(err))
169			goto err_free_rt;
170	}
171
172	skb = vlan_hwaccel_push_inside(skb);
173	if (unlikely(!skb)) {
174		err = -ENOMEM;
175		goto err_free_rt;
176	}
177
178	/* Push Tunnel header. */
179	skb = __build_header(skb, tunnel_hlen);
180	if (IS_ERR(skb)) {
181		err = PTR_ERR(skb);
182		skb = NULL;
183		goto err_free_rt;
184	}
185
186	df = tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
187		htons(IP_DF) : 0;
188
189	skb->ignore_df = 1;
190
191	return iptunnel_xmit(skb->sk, rt, skb, fl.saddr,
192			     tun_key->ipv4_dst, IPPROTO_GRE,
193			     tun_key->ipv4_tos, tun_key->ipv4_ttl, df, false);
194err_free_rt:
195	ip_rt_put(rt);
196err_free_skb:
197	kfree_skb(skb);
198	return err;
199}
200
201static struct gre_cisco_protocol gre_protocol = {
202	.handler        = gre_rcv,
203	.err_handler    = gre_err,
204	.priority       = 1,
205};
206
207static int gre_ports;
208static int gre_init(void)
209{
210	int err;
211
212	gre_ports++;
213	if (gre_ports > 1)
214		return 0;
215
216	err = gre_cisco_register(&gre_protocol);
217	if (err)
218		pr_warn("cannot register gre protocol handler\n");
219
220	return err;
221}
222
223static void gre_exit(void)
224{
225	gre_ports--;
226	if (gre_ports > 0)
227		return;
228
229	gre_cisco_unregister(&gre_protocol);
230}
231
232static const char *gre_get_name(const struct vport *vport)
233{
234	return vport_priv(vport);
235}
236
237static struct vport *gre_create(const struct vport_parms *parms)
238{
239	struct net *net = ovs_dp_get_net(parms->dp);
240	struct ovs_net *ovs_net;
241	struct vport *vport;
242	int err;
243
244	err = gre_init();
245	if (err)
246		return ERR_PTR(err);
247
248	ovs_net = net_generic(net, ovs_net_id);
249	if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
250		vport = ERR_PTR(-EEXIST);
251		goto error;
252	}
253
254	vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
255	if (IS_ERR(vport))
256		goto error;
257
258	strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
259	rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
260	return vport;
261
262error:
263	gre_exit();
264	return vport;
265}
266
267static void gre_tnl_destroy(struct vport *vport)
268{
269	struct net *net = ovs_dp_get_net(vport->dp);
270	struct ovs_net *ovs_net;
271
272	ovs_net = net_generic(net, ovs_net_id);
273
274	RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
275	ovs_vport_deferred_free(vport);
276	gre_exit();
277}
278
279static int gre_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
280				   struct ovs_tunnel_info *egress_tun_info)
281{
282	return ovs_tunnel_get_egress_info(egress_tun_info,
283					  ovs_dp_get_net(vport->dp),
284					  OVS_CB(skb)->egress_tun_info,
285					  IPPROTO_GRE, skb->mark, 0, 0);
286}
287
288static struct vport_ops ovs_gre_vport_ops = {
289	.type		= OVS_VPORT_TYPE_GRE,
290	.create		= gre_create,
291	.destroy	= gre_tnl_destroy,
292	.get_name	= gre_get_name,
293	.send		= gre_tnl_send,
294	.get_egress_tun_info	= gre_get_egress_tun_info,
295	.owner		= THIS_MODULE,
296};
297
298static int __init ovs_gre_tnl_init(void)
299{
300	return ovs_vport_ops_register(&ovs_gre_vport_ops);
301}
302
303static void __exit ovs_gre_tnl_exit(void)
304{
305	ovs_vport_ops_unregister(&ovs_gre_vport_ops);
306}
307
308module_init(ovs_gre_tnl_init);
309module_exit(ovs_gre_tnl_exit);
310
311MODULE_DESCRIPTION("OVS: GRE switching port");
312MODULE_LICENSE("GPL");
313MODULE_ALIAS("vport-type-3");
314