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
25 static 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
30 static 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
36 static 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 = dst_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 = dst_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
155 drop:
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
163 static 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
219 errout:
220 kfree(newts);
221 *ts = NULL;
222
223 return ret;
224 }
225
226 static 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
243 nla_put_failure:
244 return -EMSGSIZE;
245 }
246
247 static 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
262 static 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
279 static 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
288 static int __init mpls_iptunnel_init(void)
289 {
290 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
291 }
292 module_init(mpls_iptunnel_init);
293
294 static void __exit mpls_iptunnel_exit(void)
295 {
296 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
297 }
298 module_exit(mpls_iptunnel_exit);
299
300 MODULE_ALIAS_RTNL_LWT(MPLS);
301 MODULE_SOFTDEP("post: mpls_gso");
302 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
303 MODULE_LICENSE("GPL v2");
304
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