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	[MPLS_IPTUNNEL_TTL]	= { .type = NLA_U8 },
 33};
 34
 35static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
 36{
 37	/* The size of the layer 2.5 labels to be added for this route */
 38	return en->labels * sizeof(struct mpls_shim_hdr);
 39}
 40
 41static int mpls_xmit(struct sk_buff *skb)
 42{
 43	struct mpls_iptunnel_encap *tun_encap_info;
 44	struct mpls_shim_hdr *hdr;
 45	struct net_device *out_dev;
 46	unsigned int hh_len;
 47	unsigned int new_header_size;
 48	unsigned int mtu;
 49	struct dst_entry *dst = skb_dst(skb);
 50	struct rtable *rt = NULL;
 51	struct rt6_info *rt6 = NULL;
 52	struct mpls_dev *out_mdev;
 53	struct net *net;
 54	int err = 0;
 55	bool bos;
 56	int i;
 57	unsigned int ttl;
 58
 59	/* Find the output device */
 60	out_dev = dst->dev;
 61	net = dev_net(out_dev);
 62
 63	skb_orphan(skb);
 64
 65	if (!mpls_output_possible(out_dev) ||
 66	    !dst->lwtstate || skb_warn_if_lro(skb))
 67		goto drop;
 68
 69	skb_forward_csum(skb);
 70
 71	tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
 72
 73	/* Obtain the ttl using the following set of rules.
 74	 *
 75	 * LWT ttl propagation setting:
 76	 *  - disabled => use default TTL value from LWT
 77	 *  - enabled  => use TTL value from IPv4/IPv6 header
 78	 *  - default  =>
 79	 *   Global ttl propagation setting:
 80	 *    - disabled => use default TTL value from global setting
 81	 *    - enabled => use TTL value from IPv4/IPv6 header
 82	 */
 83	if (dst->ops->family == AF_INET) {
 84		if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
 85			ttl = tun_encap_info->default_ttl;
 86		else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
 87			 !net->mpls.ip_ttl_propagate)
 88			ttl = net->mpls.default_ttl;
 89		else
 90			ttl = ip_hdr(skb)->ttl;
 91		rt = (struct rtable *)dst;
 92	} else if (dst->ops->family == AF_INET6) {
 93		if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
 94			ttl = tun_encap_info->default_ttl;
 95		else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
 96			 !net->mpls.ip_ttl_propagate)
 97			ttl = net->mpls.default_ttl;
 98		else
 99			ttl = ipv6_hdr(skb)->hop_limit;
100		rt6 = (struct rt6_info *)dst;
101	} else {
102		goto drop;
103	}
104
105	/* Verify the destination can hold the packet */
106	new_header_size = mpls_encap_size(tun_encap_info);
107	mtu = mpls_dev_mtu(out_dev);
108	if (mpls_pkt_too_big(skb, mtu - new_header_size))
109		goto drop;
110
111	hh_len = LL_RESERVED_SPACE(out_dev);
112	if (!out_dev->header_ops)
113		hh_len = 0;
114
115	/* Ensure there is enough space for the headers in the skb */
116	if (skb_cow(skb, hh_len + new_header_size))
117		goto drop;
118
119	skb_set_inner_protocol(skb, skb->protocol);
120	skb_reset_inner_network_header(skb);
121
122	skb_push(skb, new_header_size);
123
124	skb_reset_network_header(skb);
125
126	skb->dev = out_dev;
127	skb->protocol = htons(ETH_P_MPLS_UC);
128
129	/* Push the new labels */
130	hdr = mpls_hdr(skb);
131	bos = true;
132	for (i = tun_encap_info->labels - 1; i >= 0; i--) {
133		hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
134					   ttl, 0, bos);
135		bos = false;
136	}
137
138	mpls_stats_inc_outucastpkts(out_dev, skb);
139
140	if (rt)
141		err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
142				 skb);
143	else if (rt6)
144		err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
145				 skb);
146	if (err)
147		net_dbg_ratelimited("%s: packet transmission failed: %d\n",
148				    __func__, err);
149
150	return LWTUNNEL_XMIT_DONE;
151
152drop:
153	out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
154	if (out_mdev)
155		MPLS_INC_STATS(out_mdev, tx_errors);
156	kfree_skb(skb);
157	return -EINVAL;
158}
159
160static int mpls_build_state(struct nlattr *nla,
161			    unsigned int family, const void *cfg,
162			    struct lwtunnel_state **ts,
163			    struct netlink_ext_ack *extack)
164{
165	struct mpls_iptunnel_encap *tun_encap_info;
166	struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
167	struct lwtunnel_state *newts;
168	u8 n_labels;
169	int ret;
170
171	ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
172			       mpls_iptunnel_policy, extack);
173	if (ret < 0)
174		return ret;
175
176	if (!tb[MPLS_IPTUNNEL_DST]) {
177		NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing");
178		return -EINVAL;
179	}
180
181	/* determine number of labels */
182	if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
183			   &n_labels, NULL, extack))
184		return -EINVAL;
185
186	newts = lwtunnel_state_alloc(sizeof(*tun_encap_info) +
187				     n_labels * sizeof(u32));
188	if (!newts)
189		return -ENOMEM;
190
191	tun_encap_info = mpls_lwtunnel_encap(newts);
192	ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels,
193			     &tun_encap_info->labels, tun_encap_info->label,
194			     extack);
195	if (ret)
196		goto errout;
197
198	tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT;
199
200	if (tb[MPLS_IPTUNNEL_TTL]) {
201		tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]);
202		/* TTL 0 implies propagate from IP header */
203		tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ?
204			MPLS_TTL_PROP_DISABLED :
205			MPLS_TTL_PROP_ENABLED;
206	}
207
208	newts->type = LWTUNNEL_ENCAP_MPLS;
209	newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
210	newts->headroom = mpls_encap_size(tun_encap_info);
211
212	*ts = newts;
213
214	return 0;
215
216errout:
217	kfree(newts);
218	*ts = NULL;
219
220	return ret;
221}
222
223static int mpls_fill_encap_info(struct sk_buff *skb,
224				struct lwtunnel_state *lwtstate)
225{
226	struct mpls_iptunnel_encap *tun_encap_info;
227	
228	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
229
230	if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
231			   tun_encap_info->label))
232		goto nla_put_failure;
233
234	if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT &&
235	    nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl))
236		goto nla_put_failure;
237
238	return 0;
239
240nla_put_failure:
241	return -EMSGSIZE;
242}
243
244static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
245{
246	struct mpls_iptunnel_encap *tun_encap_info;
247	int nlsize;
248
249	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
250
251	nlsize = nla_total_size(tun_encap_info->labels * 4);
252
253	if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT)
254		nlsize += nla_total_size(1);
255
256	return nlsize;
257}
258
259static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
260{
261	struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
262	struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
263	int l;
264
265	if (a_hdr->labels != b_hdr->labels ||
266	    a_hdr->ttl_propagate != b_hdr->ttl_propagate ||
267	    a_hdr->default_ttl != b_hdr->default_ttl)
268		return 1;
269
270	for (l = 0; l < a_hdr->labels; l++)
271		if (a_hdr->label[l] != b_hdr->label[l])
272			return 1;
273	return 0;
274}
275
276static const struct lwtunnel_encap_ops mpls_iptun_ops = {
277	.build_state = mpls_build_state,
278	.xmit = mpls_xmit,
279	.fill_encap = mpls_fill_encap_info,
280	.get_encap_size = mpls_encap_nlsize,
281	.cmp_encap = mpls_encap_cmp,
282	.owner = THIS_MODULE,
283};
284
285static int __init mpls_iptunnel_init(void)
286{
287	return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
288}
289module_init(mpls_iptunnel_init);
290
291static void __exit mpls_iptunnel_exit(void)
292{
293	lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
294}
295module_exit(mpls_iptunnel_exit);
296
297MODULE_ALIAS_RTNL_LWT(MPLS);
298MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
299MODULE_LICENSE("GPL v2");