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 DEFINE_STATIC_KEY_FALSE(nf_hooks_lwtunnel_enabled);
27 EXPORT_SYMBOL_GPL(nf_hooks_lwtunnel_enabled);
28
29 #ifdef CONFIG_MODULES
30
lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)31 static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
32 {
33 /* Only lwt encaps implemented without using an interface for
34 * the encap need to return a string here.
35 */
36 switch (encap_type) {
37 case LWTUNNEL_ENCAP_MPLS:
38 return "MPLS";
39 case LWTUNNEL_ENCAP_ILA:
40 return "ILA";
41 case LWTUNNEL_ENCAP_SEG6:
42 return "SEG6";
43 case LWTUNNEL_ENCAP_BPF:
44 return "BPF";
45 case LWTUNNEL_ENCAP_SEG6_LOCAL:
46 return "SEG6LOCAL";
47 case LWTUNNEL_ENCAP_RPL:
48 return "RPL";
49 case LWTUNNEL_ENCAP_IOAM6:
50 return "IOAM6";
51 case LWTUNNEL_ENCAP_XFRM:
52 /* module autoload not supported for encap type */
53 return NULL;
54 case LWTUNNEL_ENCAP_IP6:
55 case LWTUNNEL_ENCAP_IP:
56 case LWTUNNEL_ENCAP_NONE:
57 case __LWTUNNEL_ENCAP_MAX:
58 /* should not have got here */
59 WARN_ON(1);
60 break;
61 }
62 return NULL;
63 }
64
65 #endif /* CONFIG_MODULES */
66
lwtunnel_state_alloc(int encap_len)67 struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
68 {
69 struct lwtunnel_state *lws;
70
71 lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
72
73 return lws;
74 }
75 EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
76
77 static const struct lwtunnel_encap_ops __rcu *
78 lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
79
lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops * ops,unsigned int num)80 int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
81 unsigned int num)
82 {
83 if (num > LWTUNNEL_ENCAP_MAX)
84 return -ERANGE;
85
86 return !cmpxchg((const struct lwtunnel_encap_ops **)
87 &lwtun_encaps[num],
88 NULL, ops) ? 0 : -1;
89 }
90 EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
91
lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops * ops,unsigned int encap_type)92 int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
93 unsigned int encap_type)
94 {
95 int ret;
96
97 if (encap_type == LWTUNNEL_ENCAP_NONE ||
98 encap_type > LWTUNNEL_ENCAP_MAX)
99 return -ERANGE;
100
101 ret = (cmpxchg((const struct lwtunnel_encap_ops **)
102 &lwtun_encaps[encap_type],
103 ops, NULL) == ops) ? 0 : -1;
104
105 synchronize_net();
106
107 return ret;
108 }
109 EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
110
lwtunnel_build_state(struct net * net,u16 encap_type,struct nlattr * encap,unsigned int family,const void * cfg,struct lwtunnel_state ** lws,struct netlink_ext_ack * extack)111 int lwtunnel_build_state(struct net *net, u16 encap_type,
112 struct nlattr *encap, unsigned int family,
113 const void *cfg, struct lwtunnel_state **lws,
114 struct netlink_ext_ack *extack)
115 {
116 const struct lwtunnel_encap_ops *ops;
117 bool found = false;
118 int ret = -EINVAL;
119
120 if (encap_type == LWTUNNEL_ENCAP_NONE ||
121 encap_type > LWTUNNEL_ENCAP_MAX) {
122 NL_SET_ERR_MSG_ATTR(extack, encap,
123 "Unknown LWT encapsulation type");
124 return ret;
125 }
126
127 ret = -EOPNOTSUPP;
128 rcu_read_lock();
129 ops = rcu_dereference(lwtun_encaps[encap_type]);
130 if (likely(ops && ops->build_state && try_module_get(ops->owner)))
131 found = true;
132 rcu_read_unlock();
133
134 if (found) {
135 ret = ops->build_state(net, encap, family, cfg, lws, extack);
136 if (ret)
137 module_put(ops->owner);
138 } else {
139 /* don't rely on -EOPNOTSUPP to detect match as build_state
140 * handlers could return it
141 */
142 NL_SET_ERR_MSG_ATTR(extack, encap,
143 "LWT encapsulation type not supported");
144 }
145
146 return ret;
147 }
148 EXPORT_SYMBOL_GPL(lwtunnel_build_state);
149
lwtunnel_valid_encap_type(u16 encap_type,struct netlink_ext_ack * extack)150 int lwtunnel_valid_encap_type(u16 encap_type, struct netlink_ext_ack *extack)
151 {
152 const struct lwtunnel_encap_ops *ops;
153 int ret = -EINVAL;
154
155 if (encap_type == LWTUNNEL_ENCAP_NONE ||
156 encap_type > LWTUNNEL_ENCAP_MAX) {
157 NL_SET_ERR_MSG(extack, "Unknown lwt encapsulation type");
158 return ret;
159 }
160
161 rcu_read_lock();
162 ops = rcu_dereference(lwtun_encaps[encap_type]);
163 rcu_read_unlock();
164 #ifdef CONFIG_MODULES
165 if (!ops) {
166 const char *encap_type_str = lwtunnel_encap_str(encap_type);
167
168 if (encap_type_str) {
169 __rtnl_unlock();
170 request_module("rtnl-lwt-%s", encap_type_str);
171 rtnl_lock();
172
173 rcu_read_lock();
174 ops = rcu_dereference(lwtun_encaps[encap_type]);
175 rcu_read_unlock();
176 }
177 }
178 #endif
179 ret = ops ? 0 : -EOPNOTSUPP;
180 if (ret < 0)
181 NL_SET_ERR_MSG(extack, "lwt encapsulation type not supported");
182
183 return ret;
184 }
185 EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
186
lwtunnel_valid_encap_type_attr(struct nlattr * attr,int remaining,struct netlink_ext_ack * extack)187 int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
188 struct netlink_ext_ack *extack)
189 {
190 struct rtnexthop *rtnh = (struct rtnexthop *)attr;
191 struct nlattr *nla_entype;
192 struct nlattr *attrs;
193 u16 encap_type;
194 int attrlen;
195
196 while (rtnh_ok(rtnh, remaining)) {
197 attrlen = rtnh_attrlen(rtnh);
198 if (attrlen > 0) {
199 attrs = rtnh_attrs(rtnh);
200 nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
201
202 if (nla_entype) {
203 if (nla_len(nla_entype) < sizeof(u16)) {
204 NL_SET_ERR_MSG(extack, "Invalid RTA_ENCAP_TYPE");
205 return -EINVAL;
206 }
207 encap_type = nla_get_u16(nla_entype);
208
209 if (lwtunnel_valid_encap_type(encap_type,
210 extack) != 0)
211 return -EOPNOTSUPP;
212 }
213 }
214 rtnh = rtnh_next(rtnh, &remaining);
215 }
216
217 return 0;
218 }
219 EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
220
lwtstate_free(struct lwtunnel_state * lws)221 void lwtstate_free(struct lwtunnel_state *lws)
222 {
223 const struct lwtunnel_encap_ops *ops = lwtun_encaps[lws->type];
224
225 if (ops->destroy_state) {
226 ops->destroy_state(lws);
227 kfree_rcu(lws, rcu);
228 } else {
229 kfree(lws);
230 }
231 module_put(ops->owner);
232 }
233 EXPORT_SYMBOL_GPL(lwtstate_free);
234
lwtunnel_fill_encap(struct sk_buff * skb,struct lwtunnel_state * lwtstate,int encap_attr,int encap_type_attr)235 int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate,
236 int encap_attr, int encap_type_attr)
237 {
238 const struct lwtunnel_encap_ops *ops;
239 struct nlattr *nest;
240 int ret;
241
242 if (!lwtstate)
243 return 0;
244
245 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
246 lwtstate->type > LWTUNNEL_ENCAP_MAX)
247 return 0;
248
249 nest = nla_nest_start_noflag(skb, encap_attr);
250 if (!nest)
251 return -EMSGSIZE;
252
253 ret = -EOPNOTSUPP;
254 rcu_read_lock();
255 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
256 if (likely(ops && ops->fill_encap))
257 ret = ops->fill_encap(skb, lwtstate);
258 rcu_read_unlock();
259
260 if (ret)
261 goto nla_put_failure;
262 nla_nest_end(skb, nest);
263 ret = nla_put_u16(skb, encap_type_attr, lwtstate->type);
264 if (ret)
265 goto nla_put_failure;
266
267 return 0;
268
269 nla_put_failure:
270 nla_nest_cancel(skb, nest);
271
272 return (ret == -EOPNOTSUPP ? 0 : ret);
273 }
274 EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
275
lwtunnel_get_encap_size(struct lwtunnel_state * lwtstate)276 int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
277 {
278 const struct lwtunnel_encap_ops *ops;
279 int ret = 0;
280
281 if (!lwtstate)
282 return 0;
283
284 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
285 lwtstate->type > LWTUNNEL_ENCAP_MAX)
286 return 0;
287
288 rcu_read_lock();
289 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
290 if (likely(ops && ops->get_encap_size))
291 ret = nla_total_size(ops->get_encap_size(lwtstate));
292 rcu_read_unlock();
293
294 return ret;
295 }
296 EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
297
lwtunnel_cmp_encap(struct lwtunnel_state * a,struct lwtunnel_state * b)298 int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
299 {
300 const struct lwtunnel_encap_ops *ops;
301 int ret = 0;
302
303 if (!a && !b)
304 return 0;
305
306 if (!a || !b)
307 return 1;
308
309 if (a->type != b->type)
310 return 1;
311
312 if (a->type == LWTUNNEL_ENCAP_NONE ||
313 a->type > LWTUNNEL_ENCAP_MAX)
314 return 0;
315
316 rcu_read_lock();
317 ops = rcu_dereference(lwtun_encaps[a->type]);
318 if (likely(ops && ops->cmp_encap))
319 ret = ops->cmp_encap(a, b);
320 rcu_read_unlock();
321
322 return ret;
323 }
324 EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
325
lwtunnel_output(struct net * net,struct sock * sk,struct sk_buff * skb)326 int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
327 {
328 struct dst_entry *dst = skb_dst(skb);
329 const struct lwtunnel_encap_ops *ops;
330 struct lwtunnel_state *lwtstate;
331 int ret = -EINVAL;
332
333 if (!dst)
334 goto drop;
335 lwtstate = dst->lwtstate;
336
337 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
338 lwtstate->type > LWTUNNEL_ENCAP_MAX)
339 return 0;
340
341 ret = -EOPNOTSUPP;
342 rcu_read_lock();
343 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
344 if (likely(ops && ops->output))
345 ret = ops->output(net, sk, skb);
346 rcu_read_unlock();
347
348 if (ret == -EOPNOTSUPP)
349 goto drop;
350
351 return ret;
352
353 drop:
354 kfree_skb(skb);
355
356 return ret;
357 }
358 EXPORT_SYMBOL_GPL(lwtunnel_output);
359
lwtunnel_xmit(struct sk_buff * skb)360 int lwtunnel_xmit(struct sk_buff *skb)
361 {
362 struct dst_entry *dst = skb_dst(skb);
363 const struct lwtunnel_encap_ops *ops;
364 struct lwtunnel_state *lwtstate;
365 int ret = -EINVAL;
366
367 if (!dst)
368 goto drop;
369
370 lwtstate = dst->lwtstate;
371
372 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
373 lwtstate->type > LWTUNNEL_ENCAP_MAX)
374 return 0;
375
376 ret = -EOPNOTSUPP;
377 rcu_read_lock();
378 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
379 if (likely(ops && ops->xmit))
380 ret = ops->xmit(skb);
381 rcu_read_unlock();
382
383 if (ret == -EOPNOTSUPP)
384 goto drop;
385
386 return ret;
387
388 drop:
389 kfree_skb(skb);
390
391 return ret;
392 }
393 EXPORT_SYMBOL_GPL(lwtunnel_xmit);
394
lwtunnel_input(struct sk_buff * skb)395 int lwtunnel_input(struct sk_buff *skb)
396 {
397 struct dst_entry *dst = skb_dst(skb);
398 const struct lwtunnel_encap_ops *ops;
399 struct lwtunnel_state *lwtstate;
400 int ret = -EINVAL;
401
402 if (!dst)
403 goto drop;
404 lwtstate = dst->lwtstate;
405
406 if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
407 lwtstate->type > LWTUNNEL_ENCAP_MAX)
408 return 0;
409
410 ret = -EOPNOTSUPP;
411 rcu_read_lock();
412 ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
413 if (likely(ops && ops->input))
414 ret = ops->input(skb);
415 rcu_read_unlock();
416
417 if (ret == -EOPNOTSUPP)
418 goto drop;
419
420 return ret;
421
422 drop:
423 kfree_skb(skb);
424
425 return ret;
426 }
427 EXPORT_SYMBOL_GPL(lwtunnel_input);
428