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 
lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)28 static 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 
lwtunnel_state_alloc(int encap_len)59 struct 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 }
67 EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
68 
69 static const struct lwtunnel_encap_ops __rcu *
70 		lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
71 
lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops * ops,unsigned int num)72 int 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 }
82 EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
83 
lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops * ops,unsigned int encap_type)84 int 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 }
101 EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
102 
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)103 int 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 }
140 EXPORT_SYMBOL_GPL(lwtunnel_build_state);
141 
lwtunnel_valid_encap_type(u16 encap_type,struct netlink_ext_ack * extack)142 int 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 }
177 EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
178 
lwtunnel_valid_encap_type_attr(struct nlattr * attr,int remaining,struct netlink_ext_ack * extack)179 int 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 }
207 EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
208 
lwtstate_free(struct lwtunnel_state * lws)209 void 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 }
221 EXPORT_SYMBOL_GPL(lwtstate_free);
222 
lwtunnel_fill_encap(struct sk_buff * skb,struct lwtunnel_state * lwtstate,int encap_attr,int encap_type_attr)223 int 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 
257 nla_put_failure:
258 	nla_nest_cancel(skb, nest);
259 
260 	return (ret == -EOPNOTSUPP ? 0 : ret);
261 }
262 EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
263 
lwtunnel_get_encap_size(struct lwtunnel_state * lwtstate)264 int 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 }
284 EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
285 
lwtunnel_cmp_encap(struct lwtunnel_state * a,struct lwtunnel_state * b)286 int 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 }
312 EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
313 
lwtunnel_output(struct net * net,struct sock * sk,struct sk_buff * skb)314 int 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 
341 drop:
342 	kfree_skb(skb);
343 
344 	return ret;
345 }
346 EXPORT_SYMBOL_GPL(lwtunnel_output);
347 
lwtunnel_xmit(struct sk_buff * skb)348 int 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 
376 drop:
377 	kfree_skb(skb);
378 
379 	return ret;
380 }
381 EXPORT_SYMBOL_GPL(lwtunnel_xmit);
382 
lwtunnel_input(struct sk_buff * skb)383 int 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 
410 drop:
411 	kfree_skb(skb);
412 
413 	return ret;
414 }
415 EXPORT_SYMBOL_GPL(lwtunnel_input);
416