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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * lwtunnel Infrastructure for light weight tunnels like mpls
4 *
5 * Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
6 */
7
8#include <linux/capability.h>
9#include <linux/module.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/uaccess.h>
14#include <linux/skbuff.h>
15#include <linux/netdevice.h>
16#include <linux/lwtunnel.h>
17#include <linux/in.h>
18#include <linux/init.h>
19#include <linux/err.h>
20
21#include <net/lwtunnel.h>
22#include <net/rtnetlink.h>
23#include <net/ip6_fib.h>
24#include <net/rtnh.h>
25
26#ifdef CONFIG_MODULES
27
28static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
29{
30 /* Only lwt encaps implemented without using an interface for
31 * the encap need to return a string here.
32 */
33 switch (encap_type) {
34 case LWTUNNEL_ENCAP_MPLS:
35 return "MPLS";
36 case LWTUNNEL_ENCAP_ILA:
37 return "ILA";
38 case LWTUNNEL_ENCAP_SEG6:
39 return "SEG6";
40 case LWTUNNEL_ENCAP_BPF:
41 return "BPF";
42 case LWTUNNEL_ENCAP_SEG6_LOCAL:
43 return "SEG6LOCAL";
44 case LWTUNNEL_ENCAP_RPL:
45 return "RPL";
46 case LWTUNNEL_ENCAP_IP6:
47 case LWTUNNEL_ENCAP_IP:
48 case LWTUNNEL_ENCAP_NONE:
49 case __LWTUNNEL_ENCAP_MAX:
50 /* should not have got here */
51 WARN_ON(1);
52 break;
53 }
54 return NULL;
55}
56
57#endif /* CONFIG_MODULES */
58
59struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
60{
61 struct lwtunnel_state *lws;
62
63 lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
64
65 return lws;
66}
67EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
68
69static const struct lwtunnel_encap_ops __rcu *
70 lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
71
72int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
73 unsigned int num)
74{
75 if (num > LWTUNNEL_ENCAP_MAX)
76 return -ERANGE;
77
78 return !cmpxchg((const struct lwtunnel_encap_ops **)
79 &lwtun_encaps[num],
80 NULL, ops) ? 0 : -1;
81}
82EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
83
84int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
85 unsigned int encap_type)
86{
87 int ret;
88
89 if (encap_type == LWTUNNEL_ENCAP_NONE ||
90 encap_type > LWTUNNEL_ENCAP_MAX)
91 return -ERANGE;
92
93 ret = (cmpxchg((const struct lwtunnel_encap_ops **)
94 &lwtun_encaps[encap_type],
95 ops, NULL) == ops) ? 0 : -1;
96
97 synchronize_net();
98
99 return ret;
100}
101EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
102
103int lwtunnel_build_state(struct net *net, u16 encap_type,
104 struct nlattr *encap, unsigned int family,
105 const void *cfg, struct lwtunnel_state **lws,
106 struct netlink_ext_ack *extack)
107{
108 const struct lwtunnel_encap_ops *ops;
109 bool found = false;
110 int ret = -EINVAL;
111
112 if (encap_type == LWTUNNEL_ENCAP_NONE ||
113 encap_type > LWTUNNEL_ENCAP_MAX) {
114 NL_SET_ERR_MSG_ATTR(extack, encap,
115 "Unknown LWT encapsulation type");
116 return ret;
117 }
118
119 ret = -EOPNOTSUPP;
120 rcu_read_lock();
121 ops = rcu_dereference(lwtun_encaps[encap_type]);
122 if (likely(ops && ops->build_state && try_module_get(ops->owner)))
123 found = true;
124 rcu_read_unlock();
125
126 if (found) {
127 ret = ops->build_state(net, encap, family, cfg, lws, extack);
128 if (ret)
129 module_put(ops->owner);
130 } else {
131 /* don't rely on -EOPNOTSUPP to detect match as build_state
132 * handlers could return it
133 */
134 NL_SET_ERR_MSG_ATTR(extack, encap,
135 "LWT encapsulation type not supported");
136 }
137
138 return ret;
139}
140EXPORT_SYMBOL_GPL(lwtunnel_build_state);
141
142int lwtunnel_valid_encap_type(u16 encap_type, struct netlink_ext_ack *extack)
143{
144 const struct lwtunnel_encap_ops *ops;
145 int ret = -EINVAL;
146
147 if (encap_type == LWTUNNEL_ENCAP_NONE ||
148 encap_type > LWTUNNEL_ENCAP_MAX) {
149 NL_SET_ERR_MSG(extack, "Unknown lwt encapsulation type");
150 return ret;
151 }
152
153 rcu_read_lock();
154 ops = rcu_dereference(lwtun_encaps[encap_type]);
155 rcu_read_unlock();
156#ifdef CONFIG_MODULES
157 if (!ops) {
158 const char *encap_type_str = lwtunnel_encap_str(encap_type);
159
160 if (encap_type_str) {
161 __rtnl_unlock();
162 request_module("rtnl-lwt-%s", encap_type_str);
163 rtnl_lock();
164
165 rcu_read_lock();
166 ops = rcu_dereference(lwtun_encaps[encap_type]);
167 rcu_read_unlock();
168 }
169 }
170#endif
171 ret = ops ? 0 : -EOPNOTSUPP;
172 if (ret < 0)
173 NL_SET_ERR_MSG(extack, "lwt encapsulation type not supported");
174
175 return ret;
176}
177EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
178
179int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
180 struct netlink_ext_ack *extack)
181{
182 struct rtnexthop *rtnh = (struct rtnexthop *)attr;
183 struct nlattr *nla_entype;
184 struct nlattr *attrs;
185 u16 encap_type;
186 int attrlen;
187
188 while (rtnh_ok(rtnh, remaining)) {
189 attrlen = rtnh_attrlen(rtnh);
190 if (attrlen > 0) {
191 attrs = rtnh_attrs(rtnh);
192 nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
193
194 if (nla_entype) {
195 encap_type = nla_get_u16(nla_entype);
196
197 if (lwtunnel_valid_encap_type(encap_type,
198 extack) != 0)
199 return -EOPNOTSUPP;
200 }
201 }
202 rtnh = rtnh_next(rtnh, &remaining);
203 }
204
205 return 0;
206}
207EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
208
209void lwtstate_free(struct lwtunnel_state *lws)
210{
211 const struct lwtunnel_encap_ops *ops = lwtun_encaps[lws->type];
212
213 if (ops->destroy_state) {
214 ops->destroy_state(lws);
215 kfree_rcu(lws, rcu);
216 } else {
217 kfree(lws);
218 }
219 module_put(ops->owner);
220}
221EXPORT_SYMBOL_GPL(lwtstate_free);
222
223int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
224 int encap_attr, int encap_type_attr)
225{
226 const struct lwtunnel_encap_ops *ops;
227 struct nlattr *nest;
228 int ret;
229
230 if (!lwtstate)
231 return 0;
232
233 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
234 lwtstate->type > LWTUNNEL_ENCAP_MAX)
235 return 0;
236
237 nest = nla_nest_start_noflag(skb, encap_attr);
238 if (!nest)
239 return -EMSGSIZE;
240
241 ret = -EOPNOTSUPP;
242 rcu_read_lock();
243 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
244 if (likely(ops && ops->fill_encap))
245 ret = ops->fill_encap(skb, lwtstate);
246 rcu_read_unlock();
247
248 if (ret)
249 goto nla_put_failure;
250 nla_nest_end(skb, nest);
251 ret = nla_put_u16(skb, encap_type_attr, lwtstate->type);
252 if (ret)
253 goto nla_put_failure;
254
255 return 0;
256
257nla_put_failure:
258 nla_nest_cancel(skb, nest);
259
260 return (ret == -EOPNOTSUPP ? 0 : ret);
261}
262EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
263
264int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
265{
266 const struct lwtunnel_encap_ops *ops;
267 int ret = 0;
268
269 if (!lwtstate)
270 return 0;
271
272 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
273 lwtstate->type > LWTUNNEL_ENCAP_MAX)
274 return 0;
275
276 rcu_read_lock();
277 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
278 if (likely(ops && ops->get_encap_size))
279 ret = nla_total_size(ops->get_encap_size(lwtstate));
280 rcu_read_unlock();
281
282 return ret;
283}
284EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
285
286int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
287{
288 const struct lwtunnel_encap_ops *ops;
289 int ret = 0;
290
291 if (!a && !b)
292 return 0;
293
294 if (!a || !b)
295 return 1;
296
297 if (a->type != b->type)
298 return 1;
299
300 if (a->type == LWTUNNEL_ENCAP_NONE ||
301 a->type > LWTUNNEL_ENCAP_MAX)
302 return 0;
303
304 rcu_read_lock();
305 ops = rcu_dereference(lwtun_encaps[a->type]);
306 if (likely(ops && ops->cmp_encap))
307 ret = ops->cmp_encap(a, b);
308 rcu_read_unlock();
309
310 return ret;
311}
312EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
313
314int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
315{
316 struct dst_entry *dst = skb_dst(skb);
317 const struct lwtunnel_encap_ops *ops;
318 struct lwtunnel_state *lwtstate;
319 int ret = -EINVAL;
320
321 if (!dst)
322 goto drop;
323 lwtstate = dst->lwtstate;
324
325 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
326 lwtstate->type > LWTUNNEL_ENCAP_MAX)
327 return 0;
328
329 ret = -EOPNOTSUPP;
330 rcu_read_lock();
331 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
332 if (likely(ops && ops->output))
333 ret = ops->output(net, sk, skb);
334 rcu_read_unlock();
335
336 if (ret == -EOPNOTSUPP)
337 goto drop;
338
339 return ret;
340
341drop:
342 kfree_skb(skb);
343
344 return ret;
345}
346EXPORT_SYMBOL_GPL(lwtunnel_output);
347
348int lwtunnel_xmit(struct sk_buff *skb)
349{
350 struct dst_entry *dst = skb_dst(skb);
351 const struct lwtunnel_encap_ops *ops;
352 struct lwtunnel_state *lwtstate;
353 int ret = -EINVAL;
354
355 if (!dst)
356 goto drop;
357
358 lwtstate = dst->lwtstate;
359
360 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
361 lwtstate->type > LWTUNNEL_ENCAP_MAX)
362 return 0;
363
364 ret = -EOPNOTSUPP;
365 rcu_read_lock();
366 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
367 if (likely(ops && ops->xmit))
368 ret = ops->xmit(skb);
369 rcu_read_unlock();
370
371 if (ret == -EOPNOTSUPP)
372 goto drop;
373
374 return ret;
375
376drop:
377 kfree_skb(skb);
378
379 return ret;
380}
381EXPORT_SYMBOL_GPL(lwtunnel_xmit);
382
383int lwtunnel_input(struct sk_buff *skb)
384{
385 struct dst_entry *dst = skb_dst(skb);
386 const struct lwtunnel_encap_ops *ops;
387 struct lwtunnel_state *lwtstate;
388 int ret = -EINVAL;
389
390 if (!dst)
391 goto drop;
392 lwtstate = dst->lwtstate;
393
394 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
395 lwtstate->type > LWTUNNEL_ENCAP_MAX)
396 return 0;
397
398 ret = -EOPNOTSUPP;
399 rcu_read_lock();
400 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
401 if (likely(ops && ops->input))
402 ret = ops->input(skb);
403 rcu_read_unlock();
404
405 if (ret == -EOPNOTSUPP)
406 goto drop;
407
408 return ret;
409
410drop:
411 kfree_skb(skb);
412
413 return ret;
414}
415EXPORT_SYMBOL_GPL(lwtunnel_input);