1/*
2 * mpls tunnels	An implementation mpls tunnels using the light weight tunnel
3 *		infrastructure
4 *
5 * Authors:	Roopa Prabhu, <roopa@cumulusnetworks.com>
6 *
7 *		This program is free software; you can redistribute it and/or
8 *		modify it under the terms of the GNU General Public License
9 *		as published by the Free Software Foundation; either version
10 *		2 of the License, or (at your option) any later version.
11 *
12 */
13#include <linux/types.h>
14#include <linux/skbuff.h>
15#include <linux/net.h>
16#include <linux/module.h>
17#include <linux/mpls.h>
18#include <linux/vmalloc.h>
19#include <net/ip.h>
20#include <net/dst.h>
21#include <net/lwtunnel.h>
22#include <net/netevent.h>
23#include <net/netns/generic.h>
24#include <net/ip6_fib.h>
25#include <net/route.h>
26#include <net/mpls_iptunnel.h>
27#include <linux/mpls_iptunnel.h>
28#include "internal.h"
29
30static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
31	[MPLS_IPTUNNEL_DST]	= { .type = NLA_U32 },
32};
33
34static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
35{
36	/* The size of the layer 2.5 labels to be added for this route */
37	return en->labels * sizeof(struct mpls_shim_hdr);
38}
39
40int mpls_output(struct net *net, struct sock *sk, struct sk_buff *skb)
41{
42	struct mpls_iptunnel_encap *tun_encap_info;
43	struct mpls_shim_hdr *hdr;
44	struct net_device *out_dev;
45	unsigned int hh_len;
46	unsigned int new_header_size;
47	unsigned int mtu;
48	struct dst_entry *dst = skb_dst(skb);
49	struct rtable *rt = NULL;
50	struct rt6_info *rt6 = NULL;
51	int err = 0;
52	bool bos;
53	int i;
54	unsigned int ttl;
55
56	/* Obtain the ttl */
57	if (dst->ops->family == AF_INET) {
58		ttl = ip_hdr(skb)->ttl;
59		rt = (struct rtable *)dst;
60	} else if (dst->ops->family == AF_INET6) {
61		ttl = ipv6_hdr(skb)->hop_limit;
62		rt6 = (struct rt6_info *)dst;
63	} else {
64		goto drop;
65	}
66
67	skb_orphan(skb);
68
69	/* Find the output device */
70	out_dev = dst->dev;
71	if (!mpls_output_possible(out_dev) ||
72	    !dst->lwtstate || skb_warn_if_lro(skb))
73		goto drop;
74
75	skb_forward_csum(skb);
76
77	tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
78
79	/* Verify the destination can hold the packet */
80	new_header_size = mpls_encap_size(tun_encap_info);
81	mtu = mpls_dev_mtu(out_dev);
82	if (mpls_pkt_too_big(skb, mtu - new_header_size))
83		goto drop;
84
85	hh_len = LL_RESERVED_SPACE(out_dev);
86	if (!out_dev->header_ops)
87		hh_len = 0;
88
89	/* Ensure there is enough space for the headers in the skb */
90	if (skb_cow(skb, hh_len + new_header_size))
91		goto drop;
92
93	skb_push(skb, new_header_size);
94	skb_reset_network_header(skb);
95
96	skb->dev = out_dev;
97	skb->protocol = htons(ETH_P_MPLS_UC);
98
99	/* Push the new labels */
100	hdr = mpls_hdr(skb);
101	bos = true;
102	for (i = tun_encap_info->labels - 1; i >= 0; i--) {
103		hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
104					   ttl, 0, bos);
105		bos = false;
106	}
107
108	if (rt)
109		err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
110				 skb);
111	else if (rt6)
112		err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
113				 skb);
114	if (err)
115		net_dbg_ratelimited("%s: packet transmission failed: %d\n",
116				    __func__, err);
117
118	return 0;
119
120drop:
121	kfree_skb(skb);
122	return -EINVAL;
123}
124
125static int mpls_build_state(struct net_device *dev, struct nlattr *nla,
126			    unsigned int family, const void *cfg,
127			    struct lwtunnel_state **ts)
128{
129	struct mpls_iptunnel_encap *tun_encap_info;
130	struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
131	struct lwtunnel_state *newts;
132	int tun_encap_info_len;
133	int ret;
134
135	ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
136			       mpls_iptunnel_policy);
137	if (ret < 0)
138		return ret;
139
140	if (!tb[MPLS_IPTUNNEL_DST])
141		return -EINVAL;
142
143	tun_encap_info_len = sizeof(*tun_encap_info);
144
145	newts = lwtunnel_state_alloc(tun_encap_info_len);
146	if (!newts)
147		return -ENOMEM;
148
149	newts->len = tun_encap_info_len;
150	tun_encap_info = mpls_lwtunnel_encap(newts);
151	ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
152			     &tun_encap_info->labels, tun_encap_info->label);
153	if (ret)
154		goto errout;
155	newts->type = LWTUNNEL_ENCAP_MPLS;
156	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
157
158	*ts = newts;
159
160	return 0;
161
162errout:
163	kfree(newts);
164	*ts = NULL;
165
166	return ret;
167}
168
169static int mpls_fill_encap_info(struct sk_buff *skb,
170				struct lwtunnel_state *lwtstate)
171{
172	struct mpls_iptunnel_encap *tun_encap_info;
173
174	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
175
176	if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
177			   tun_encap_info->label))
178		goto nla_put_failure;
179
180	return 0;
181
182nla_put_failure:
183	return -EMSGSIZE;
184}
185
186static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
187{
188	struct mpls_iptunnel_encap *tun_encap_info;
189
190	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
191
192	return nla_total_size(tun_encap_info->labels * 4);
193}
194
195static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
196{
197	struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
198	struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
199	int l;
200
201	if (a_hdr->labels != b_hdr->labels)
202		return 1;
203
204	for (l = 0; l < MAX_NEW_LABELS; l++)
205		if (a_hdr->label[l] != b_hdr->label[l])
206			return 1;
207	return 0;
208}
209
210static const struct lwtunnel_encap_ops mpls_iptun_ops = {
211	.build_state = mpls_build_state,
212	.output = mpls_output,
213	.fill_encap = mpls_fill_encap_info,
214	.get_encap_size = mpls_encap_nlsize,
215	.cmp_encap = mpls_encap_cmp,
216};
217
218static int __init mpls_iptunnel_init(void)
219{
220	return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
221}
222module_init(mpls_iptunnel_init);
223
224static void __exit mpls_iptunnel_exit(void)
225{
226	lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
227}
228module_exit(mpls_iptunnel_exit);
229
230MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
231MODULE_LICENSE("GPL v2");
232