1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * mpls tunnels	An implementation mpls tunnels using the light weight tunnel
4 *		infrastructure
5 *
6 * Authors:	Roopa Prabhu, <roopa@cumulusnetworks.com>
7 */
8#include <linux/types.h>
9#include <linux/skbuff.h>
10#include <linux/net.h>
11#include <linux/module.h>
12#include <linux/mpls.h>
13#include <linux/vmalloc.h>
14#include <net/ip.h>
15#include <net/dst.h>
16#include <net/lwtunnel.h>
17#include <net/netevent.h>
18#include <net/netns/generic.h>
19#include <net/ip6_fib.h>
20#include <net/route.h>
21#include <net/mpls_iptunnel.h>
22#include <linux/mpls_iptunnel.h>
23#include "internal.h"
24
25static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
26	[MPLS_IPTUNNEL_DST]	= { .len = sizeof(u32) },
27	[MPLS_IPTUNNEL_TTL]	= { .type = NLA_U8 },
28};
29
30static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
31{
32	/* The size of the layer 2.5 labels to be added for this route */
33	return en->labels * sizeof(struct mpls_shim_hdr);
34}
35
36static int mpls_xmit(struct sk_buff *skb)
37{
38	struct mpls_iptunnel_encap *tun_encap_info;
39	struct mpls_shim_hdr *hdr;
40	struct net_device *out_dev;
41	unsigned int hh_len;
42	unsigned int new_header_size;
43	unsigned int mtu;
44	struct dst_entry *dst = skb_dst(skb);
45	struct rtable *rt = NULL;
46	struct rt6_info *rt6 = NULL;
47	struct mpls_dev *out_mdev;
48	struct net *net;
49	int err = 0;
50	bool bos;
51	int i;
52	unsigned int ttl;
53
54	/* Find the output device */
55	out_dev = dst->dev;
56	net = dev_net(out_dev);
57
58	if (!mpls_output_possible(out_dev) ||
59	    !dst->lwtstate || skb_warn_if_lro(skb))
60		goto drop;
61
62	skb_forward_csum(skb);
63
64	tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
65
66	/* Obtain the ttl using the following set of rules.
67	 *
68	 * LWT ttl propagation setting:
69	 *  - disabled => use default TTL value from LWT
70	 *  - enabled  => use TTL value from IPv4/IPv6 header
71	 *  - default  =>
72	 *   Global ttl propagation setting:
73	 *    - disabled => use default TTL value from global setting
74	 *    - enabled => use TTL value from IPv4/IPv6 header
75	 */
76	if (dst->ops->family == AF_INET) {
77		if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
78			ttl = tun_encap_info->default_ttl;
79		else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
80			 !net->mpls.ip_ttl_propagate)
81			ttl = net->mpls.default_ttl;
82		else
83			ttl = ip_hdr(skb)->ttl;
84		rt = (struct rtable *)dst;
85	} else if (dst->ops->family == AF_INET6) {
86		if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
87			ttl = tun_encap_info->default_ttl;
88		else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
89			 !net->mpls.ip_ttl_propagate)
90			ttl = net->mpls.default_ttl;
91		else
92			ttl = ipv6_hdr(skb)->hop_limit;
93		rt6 = (struct rt6_info *)dst;
94	} else {
95		goto drop;
96	}
97
98	/* Verify the destination can hold the packet */
99	new_header_size = mpls_encap_size(tun_encap_info);
100	mtu = mpls_dev_mtu(out_dev);
101	if (mpls_pkt_too_big(skb, mtu - new_header_size))
102		goto drop;
103
104	hh_len = LL_RESERVED_SPACE(out_dev);
105	if (!out_dev->header_ops)
106		hh_len = 0;
107
108	/* Ensure there is enough space for the headers in the skb */
109	if (skb_cow(skb, hh_len + new_header_size))
110		goto drop;
111
112	skb_set_inner_protocol(skb, skb->protocol);
113	skb_reset_inner_network_header(skb);
114
115	skb_push(skb, new_header_size);
116
117	skb_reset_network_header(skb);
118
119	skb->dev = out_dev;
120	skb->protocol = htons(ETH_P_MPLS_UC);
121
122	/* Push the new labels */
123	hdr = mpls_hdr(skb);
124	bos = true;
125	for (i = tun_encap_info->labels - 1; i >= 0; i--) {
126		hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
127					   ttl, 0, bos);
128		bos = false;
129	}
130
131	mpls_stats_inc_outucastpkts(out_dev, skb);
132
133	if (rt) {
134		if (rt->rt_gw_family == AF_INET6)
135			err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt->rt_gw6,
136					 skb);
137		else
138			err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gw4,
139					 skb);
140	} else if (rt6) {
141		if (ipv6_addr_v4mapped(&rt6->rt6i_gateway)) {
142			/* 6PE (RFC 4798) */
143			err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt6->rt6i_gateway.s6_addr32[3],
144					 skb);
145		} else
146			err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
147					 skb);
148	}
149	if (err)
150		net_dbg_ratelimited("%s: packet transmission failed: %d\n",
151				    __func__, err);
152
153	return LWTUNNEL_XMIT_DONE;
154
155drop:
156	out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
157	if (out_mdev)
158		MPLS_INC_STATS(out_mdev, tx_errors);
159	kfree_skb(skb);
160	return -EINVAL;
161}
162
163static int mpls_build_state(struct net *net, struct nlattr *nla,
164			    unsigned int family, const void *cfg,
165			    struct lwtunnel_state **ts,
166			    struct netlink_ext_ack *extack)
167{
168	struct mpls_iptunnel_encap *tun_encap_info;
169	struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
170	struct lwtunnel_state *newts;
171	u8 n_labels;
172	int ret;
173
174	ret = nla_parse_nested_deprecated(tb, MPLS_IPTUNNEL_MAX, nla,
175					  mpls_iptunnel_policy, extack);
176	if (ret < 0)
177		return ret;
178
179	if (!tb[MPLS_IPTUNNEL_DST]) {
180		NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing");
181		return -EINVAL;
182	}
183
184	/* determine number of labels */
185	if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
186			   &n_labels, NULL, extack))
187		return -EINVAL;
188
189	newts = lwtunnel_state_alloc(struct_size(tun_encap_info, label,
190						 n_labels));
191	if (!newts)
192		return -ENOMEM;
193
194	tun_encap_info = mpls_lwtunnel_encap(newts);
195	ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels,
196			     &tun_encap_info->labels, tun_encap_info->label,
197			     extack);
198	if (ret)
199		goto errout;
200
201	tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT;
202
203	if (tb[MPLS_IPTUNNEL_TTL]) {
204		tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]);
205		/* TTL 0 implies propagate from IP header */
206		tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ?
207			MPLS_TTL_PROP_DISABLED :
208			MPLS_TTL_PROP_ENABLED;
209	}
210
211	newts->type = LWTUNNEL_ENCAP_MPLS;
212	newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
213	newts->headroom = mpls_encap_size(tun_encap_info);
214
215	*ts = newts;
216
217	return 0;
218
219errout:
220	kfree(newts);
221	*ts = NULL;
222
223	return ret;
224}
225
226static int mpls_fill_encap_info(struct sk_buff *skb,
227				struct lwtunnel_state *lwtstate)
228{
229	struct mpls_iptunnel_encap *tun_encap_info;
230
231	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
232
233	if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
234			   tun_encap_info->label))
235		goto nla_put_failure;
236
237	if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT &&
238	    nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl))
239		goto nla_put_failure;
240
241	return 0;
242
243nla_put_failure:
244	return -EMSGSIZE;
245}
246
247static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
248{
249	struct mpls_iptunnel_encap *tun_encap_info;
250	int nlsize;
251
252	tun_encap_info = mpls_lwtunnel_encap(lwtstate);
253
254	nlsize = nla_total_size(tun_encap_info->labels * 4);
255
256	if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT)
257		nlsize += nla_total_size(1);
258
259	return nlsize;
260}
261
262static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
263{
264	struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
265	struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
266	int l;
267
268	if (a_hdr->labels != b_hdr->labels ||
269	    a_hdr->ttl_propagate != b_hdr->ttl_propagate ||
270	    a_hdr->default_ttl != b_hdr->default_ttl)
271		return 1;
272
273	for (l = 0; l < a_hdr->labels; l++)
274		if (a_hdr->label[l] != b_hdr->label[l])
275			return 1;
276	return 0;
277}
278
279static const struct lwtunnel_encap_ops mpls_iptun_ops = {
280	.build_state = mpls_build_state,
281	.xmit = mpls_xmit,
282	.fill_encap = mpls_fill_encap_info,
283	.get_encap_size = mpls_encap_nlsize,
284	.cmp_encap = mpls_encap_cmp,
285	.owner = THIS_MODULE,
286};
287
288static int __init mpls_iptunnel_init(void)
289{
290	return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
291}
292module_init(mpls_iptunnel_init);
293
294static void __exit mpls_iptunnel_exit(void)
295{
296	lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
297}
298module_exit(mpls_iptunnel_exit);
299
300MODULE_ALIAS_RTNL_LWT(MPLS);
301MODULE_SOFTDEP("post: mpls_gso");
302MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
303MODULE_LICENSE("GPL v2");
304