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
mpls_encap_size(struct mpls_iptunnel_encap * en)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
mpls_xmit(struct sk_buff * skb)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 skb_orphan(skb);
59
60 if (!mpls_output_possible(out_dev) ||
61 !dst->lwtstate || skb_warn_if_lro(skb))
62 goto drop;
63
64 skb_forward_csum(skb);
65
66 tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
67
68 /* Obtain the ttl using the following set of rules.
69 *
70 * LWT ttl propagation setting:
71 * - disabled => use default TTL value from LWT
72 * - enabled => use TTL value from IPv4/IPv6 header
73 * - default =>
74 * Global ttl propagation setting:
75 * - disabled => use default TTL value from global setting
76 * - enabled => use TTL value from IPv4/IPv6 header
77 */
78 if (dst->ops->family == AF_INET) {
79 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
80 ttl = tun_encap_info->default_ttl;
81 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
82 !net->mpls.ip_ttl_propagate)
83 ttl = net->mpls.default_ttl;
84 else
85 ttl = ip_hdr(skb)->ttl;
86 rt = (struct rtable *)dst;
87 } else if (dst->ops->family == AF_INET6) {
88 if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DISABLED)
89 ttl = tun_encap_info->default_ttl;
90 else if (tun_encap_info->ttl_propagate == MPLS_TTL_PROP_DEFAULT &&
91 !net->mpls.ip_ttl_propagate)
92 ttl = net->mpls.default_ttl;
93 else
94 ttl = ipv6_hdr(skb)->hop_limit;
95 rt6 = (struct rt6_info *)dst;
96 } else {
97 goto drop;
98 }
99
100 /* Verify the destination can hold the packet */
101 new_header_size = mpls_encap_size(tun_encap_info);
102 mtu = mpls_dev_mtu(out_dev);
103 if (mpls_pkt_too_big(skb, mtu - new_header_size))
104 goto drop;
105
106 hh_len = LL_RESERVED_SPACE(out_dev);
107 if (!out_dev->header_ops)
108 hh_len = 0;
109
110 /* Ensure there is enough space for the headers in the skb */
111 if (skb_cow(skb, hh_len + new_header_size))
112 goto drop;
113
114 skb_set_inner_protocol(skb, skb->protocol);
115 skb_reset_inner_network_header(skb);
116
117 skb_push(skb, new_header_size);
118
119 skb_reset_network_header(skb);
120
121 skb->dev = out_dev;
122 skb->protocol = htons(ETH_P_MPLS_UC);
123
124 /* Push the new labels */
125 hdr = mpls_hdr(skb);
126 bos = true;
127 for (i = tun_encap_info->labels - 1; i >= 0; i--) {
128 hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
129 ttl, 0, bos);
130 bos = false;
131 }
132
133 mpls_stats_inc_outucastpkts(out_dev, skb);
134
135 if (rt) {
136 if (rt->rt_gw_family == AF_INET6)
137 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt->rt_gw6,
138 skb);
139 else
140 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gw4,
141 skb);
142 } else if (rt6) {
143 if (ipv6_addr_v4mapped(&rt6->rt6i_gateway)) {
144 /* 6PE (RFC 4798) */
145 err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt6->rt6i_gateway.s6_addr32[3],
146 skb);
147 } else
148 err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
149 skb);
150 }
151 if (err)
152 net_dbg_ratelimited("%s: packet transmission failed: %d\n",
153 __func__, err);
154
155 return LWTUNNEL_XMIT_DONE;
156
157 drop:
158 out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
159 if (out_mdev)
160 MPLS_INC_STATS(out_mdev, tx_errors);
161 kfree_skb(skb);
162 return -EINVAL;
163 }
164
mpls_build_state(struct net * net,struct nlattr * nla,unsigned int family,const void * cfg,struct lwtunnel_state ** ts,struct netlink_ext_ack * extack)165 static int mpls_build_state(struct net *net, struct nlattr *nla,
166 unsigned int family, const void *cfg,
167 struct lwtunnel_state **ts,
168 struct netlink_ext_ack *extack)
169 {
170 struct mpls_iptunnel_encap *tun_encap_info;
171 struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
172 struct lwtunnel_state *newts;
173 u8 n_labels;
174 int ret;
175
176 ret = nla_parse_nested_deprecated(tb, MPLS_IPTUNNEL_MAX, nla,
177 mpls_iptunnel_policy, extack);
178 if (ret < 0)
179 return ret;
180
181 if (!tb[MPLS_IPTUNNEL_DST]) {
182 NL_SET_ERR_MSG(extack, "MPLS_IPTUNNEL_DST attribute is missing");
183 return -EINVAL;
184 }
185
186 /* determine number of labels */
187 if (nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
188 &n_labels, NULL, extack))
189 return -EINVAL;
190
191 newts = lwtunnel_state_alloc(struct_size(tun_encap_info, label,
192 n_labels));
193 if (!newts)
194 return -ENOMEM;
195
196 tun_encap_info = mpls_lwtunnel_encap(newts);
197 ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], n_labels,
198 &tun_encap_info->labels, tun_encap_info->label,
199 extack);
200 if (ret)
201 goto errout;
202
203 tun_encap_info->ttl_propagate = MPLS_TTL_PROP_DEFAULT;
204
205 if (tb[MPLS_IPTUNNEL_TTL]) {
206 tun_encap_info->default_ttl = nla_get_u8(tb[MPLS_IPTUNNEL_TTL]);
207 /* TTL 0 implies propagate from IP header */
208 tun_encap_info->ttl_propagate = tun_encap_info->default_ttl ?
209 MPLS_TTL_PROP_DISABLED :
210 MPLS_TTL_PROP_ENABLED;
211 }
212
213 newts->type = LWTUNNEL_ENCAP_MPLS;
214 newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
215 newts->headroom = mpls_encap_size(tun_encap_info);
216
217 *ts = newts;
218
219 return 0;
220
221 errout:
222 kfree(newts);
223 *ts = NULL;
224
225 return ret;
226 }
227
mpls_fill_encap_info(struct sk_buff * skb,struct lwtunnel_state * lwtstate)228 static int mpls_fill_encap_info(struct sk_buff *skb,
229 struct lwtunnel_state *lwtstate)
230 {
231 struct mpls_iptunnel_encap *tun_encap_info;
232
233 tun_encap_info = mpls_lwtunnel_encap(lwtstate);
234
235 if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
236 tun_encap_info->label))
237 goto nla_put_failure;
238
239 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT &&
240 nla_put_u8(skb, MPLS_IPTUNNEL_TTL, tun_encap_info->default_ttl))
241 goto nla_put_failure;
242
243 return 0;
244
245 nla_put_failure:
246 return -EMSGSIZE;
247 }
248
mpls_encap_nlsize(struct lwtunnel_state * lwtstate)249 static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
250 {
251 struct mpls_iptunnel_encap *tun_encap_info;
252 int nlsize;
253
254 tun_encap_info = mpls_lwtunnel_encap(lwtstate);
255
256 nlsize = nla_total_size(tun_encap_info->labels * 4);
257
258 if (tun_encap_info->ttl_propagate != MPLS_TTL_PROP_DEFAULT)
259 nlsize += nla_total_size(1);
260
261 return nlsize;
262 }
263
mpls_encap_cmp(struct lwtunnel_state * a,struct lwtunnel_state * b)264 static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
265 {
266 struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
267 struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
268 int l;
269
270 if (a_hdr->labels != b_hdr->labels ||
271 a_hdr->ttl_propagate != b_hdr->ttl_propagate ||
272 a_hdr->default_ttl != b_hdr->default_ttl)
273 return 1;
274
275 for (l = 0; l < a_hdr->labels; l++)
276 if (a_hdr->label[l] != b_hdr->label[l])
277 return 1;
278 return 0;
279 }
280
281 static const struct lwtunnel_encap_ops mpls_iptun_ops = {
282 .build_state = mpls_build_state,
283 .xmit = mpls_xmit,
284 .fill_encap = mpls_fill_encap_info,
285 .get_encap_size = mpls_encap_nlsize,
286 .cmp_encap = mpls_encap_cmp,
287 .owner = THIS_MODULE,
288 };
289
mpls_iptunnel_init(void)290 static int __init mpls_iptunnel_init(void)
291 {
292 return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
293 }
294 module_init(mpls_iptunnel_init);
295
mpls_iptunnel_exit(void)296 static void __exit mpls_iptunnel_exit(void)
297 {
298 lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
299 }
300 module_exit(mpls_iptunnel_exit);
301
302 MODULE_ALIAS_RTNL_LWT(MPLS);
303 MODULE_SOFTDEP("post: mpls_gso");
304 MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
305 MODULE_LICENSE("GPL v2");
306