xref: /openbmc/linux/net/mpls/mpls_iptunnel.c (revision a2cce7a9)
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 
30 static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
31 	[MPLS_IPTUNNEL_DST]	= { .type = NLA_U32 },
32 };
33 
34 static 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 
40 int mpls_output(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 (skb->protocol == htons(ETH_P_IP)) {
58 		ttl = ip_hdr(skb)->ttl;
59 		rt = (struct rtable *)dst;
60 	} else if (skb->protocol == htons(ETH_P_IPV6)) {
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 
120 drop:
121 	kfree_skb(skb);
122 	return -EINVAL;
123 }
124 
125 static 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 
162 errout:
163 	kfree(newts);
164 	*ts = NULL;
165 
166 	return ret;
167 }
168 
169 static 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 
182 nla_put_failure:
183 	return -EMSGSIZE;
184 }
185 
186 static 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 
195 static 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 
210 static 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 
218 static int __init mpls_iptunnel_init(void)
219 {
220 	return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
221 }
222 module_init(mpls_iptunnel_init);
223 
224 static void __exit mpls_iptunnel_exit(void)
225 {
226 	lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
227 }
228 module_exit(mpls_iptunnel_exit);
229 
230 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
231 MODULE_LICENSE("GPL v2");
232