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
26DEFINE_STATIC_KEY_FALSE(nf_hooks_lwtunnel_enabled);
27EXPORT_SYMBOL_GPL(nf_hooks_lwtunnel_enabled);
28
29#ifdef CONFIG_MODULES
30
31static 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
67struct 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}
75EXPORT_SYMBOL_GPL(lwtunnel_state_alloc);
76
77static const struct lwtunnel_encap_ops __rcu *
78		lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
79
80int 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}
90EXPORT_SYMBOL_GPL(lwtunnel_encap_add_ops);
91
92int 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}
109EXPORT_SYMBOL_GPL(lwtunnel_encap_del_ops);
110
111int 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}
148EXPORT_SYMBOL_GPL(lwtunnel_build_state);
149
150int 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}
185EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type);
186
187int 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}
219EXPORT_SYMBOL_GPL(lwtunnel_valid_encap_type_attr);
220
221void 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}
233EXPORT_SYMBOL_GPL(lwtstate_free);
234
235int 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
269nla_put_failure:
270	nla_nest_cancel(skb, nest);
271
272	return (ret == -EOPNOTSUPP ? 0 : ret);
273}
274EXPORT_SYMBOL_GPL(lwtunnel_fill_encap);
275
276int 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}
296EXPORT_SYMBOL_GPL(lwtunnel_get_encap_size);
297
298int 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}
324EXPORT_SYMBOL_GPL(lwtunnel_cmp_encap);
325
326int 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
353drop:
354	kfree_skb(skb);
355
356	return ret;
357}
358EXPORT_SYMBOL_GPL(lwtunnel_output);
359
360int 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
388drop:
389	kfree_skb(skb);
390
391	return ret;
392}
393EXPORT_SYMBOL_GPL(lwtunnel_xmit);
394
395int 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
422drop:
423	kfree_skb(skb);
424
425	return ret;
426}
427EXPORT_SYMBOL_GPL(lwtunnel_input);
428