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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 | [MPLS_IPTUNNEL_TTL] = { .type = NLA_U8 }, | |
33 | }; | |
34 | ||
35 | static 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 | ||
41 | static 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 | ||
152 | drop: | |
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 | ||
160 | static 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 | ||
216 | errout: | |
217 | kfree(newts); | |
218 | *ts = NULL; | |
219 | ||
220 | return ret; | |
221 | } | |
222 | ||
223 | static 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 | ||
240 | nla_put_failure: | |
241 | return -EMSGSIZE; | |
242 | } | |
243 | ||
244 | static 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 | ||
259 | static 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 | ||
276 | static 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 | ||
285 | static int __init mpls_iptunnel_init(void) | |
286 | { | |
287 | return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); | |
288 | } | |
289 | module_init(mpls_iptunnel_init); | |
290 | ||
291 | static void __exit mpls_iptunnel_exit(void) | |
292 | { | |
293 | lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS); | |
294 | } | |
295 | module_exit(mpls_iptunnel_exit); | |
296 | ||
297 | MODULE_ALIAS_RTNL_LWT(MPLS); | |
298 | MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels"); | |
299 | MODULE_LICENSE("GPL v2"); |