xref: /linux/net/sched/cls_route.c (revision 8e07e0e3964ca4e23ce7b68e2096fe660a888942) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * net/sched/cls_route.c	ROUTE4 classifier.
4  *
5  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6  */
7 
8 #include <linux/module.h>
9 #include <linux/slab.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/string.h>
13 #include <linux/errno.h>
14 #include <linux/skbuff.h>
15 #include <net/dst.h>
16 #include <net/route.h>
17 #include <net/netlink.h>
18 #include <net/act_api.h>
19 #include <net/pkt_cls.h>
20 #include <net/tc_wrapper.h>
21 
22 /*
23  * 1. For now we assume that route tags < 256.
24  *    It allows to use direct table lookups, instead of hash tables.
25  * 2. For now we assume that "from TAG" and "fromdev DEV" statements
26  *    are mutually  exclusive.
27  * 3. "to TAG from ANY" has higher priority, than "to ANY from XXX"
28  */
29 struct route4_fastmap {
30 	struct route4_filter		*filter;
31 	u32				id;
32 	int				iif;
33 };
34 
35 struct route4_head {
36 	struct route4_fastmap		fastmap[16];
37 	struct route4_bucket __rcu	*table[256 + 1];
38 	struct rcu_head			rcu;
39 };
40 
41 struct route4_bucket {
42 	/* 16 FROM buckets + 16 IIF buckets + 1 wildcard bucket */
43 	struct route4_filter __rcu	*ht[16 + 16 + 1];
44 	struct rcu_head			rcu;
45 };
46 
47 struct route4_filter {
48 	struct route4_filter __rcu	*next;
49 	u32			id;
50 	int			iif;
51 
52 	struct tcf_result	res;
53 	struct tcf_exts		exts;
54 	u32			handle;
55 	struct route4_bucket	*bkt;
56 	struct tcf_proto	*tp;
57 	struct rcu_work		rwork;
58 };
59 
60 #define ROUTE4_FAILURE ((struct route4_filter *)(-1L))
61 
62 static inline int route4_fastmap_hash(u32 id, int iif)
63 {
64 	return id & 0xF;
65 }
66 
67 static DEFINE_SPINLOCK(fastmap_lock);
68 static void
69 route4_reset_fastmap(struct route4_head *head)
70 {
71 	spin_lock_bh(&fastmap_lock);
72 	memset(head->fastmap, 0, sizeof(head->fastmap));
73 	spin_unlock_bh(&fastmap_lock);
74 }
75 
76 static void
77 route4_set_fastmap(struct route4_head *head, u32 id, int iif,
78 		   struct route4_filter *f)
79 {
80 	int h = route4_fastmap_hash(id, iif);
81 
82 	/* fastmap updates must look atomic to aling id, iff, filter */
83 	spin_lock_bh(&fastmap_lock);
84 	head->fastmap[h].id = id;
85 	head->fastmap[h].iif = iif;
86 	head->fastmap[h].filter = f;
87 	spin_unlock_bh(&fastmap_lock);
88 }
89 
90 static inline int route4_hash_to(u32 id)
91 {
92 	return id & 0xFF;
93 }
94 
95 static inline int route4_hash_from(u32 id)
96 {
97 	return (id >> 16) & 0xF;
98 }
99 
100 static inline int route4_hash_iif(int iif)
101 {
102 	return 16 + ((iif >> 16) & 0xF);
103 }
104 
105 static inline int route4_hash_wild(void)
106 {
107 	return 32;
108 }
109 
110 #define ROUTE4_APPLY_RESULT()					\
111 {								\
112 	*res = f->res;						\
113 	if (tcf_exts_has_actions(&f->exts)) {			\
114 		int r = tcf_exts_exec(skb, &f->exts, res);	\
115 		if (r < 0) {					\
116 			dont_cache = 1;				\
117 			continue;				\
118 		}						\
119 		return r;					\
120 	} else if (!dont_cache)					\
121 		route4_set_fastmap(head, id, iif, f);		\
122 	return 0;						\
123 }
124 
125 TC_INDIRECT_SCOPE int route4_classify(struct sk_buff *skb,
126 				      const struct tcf_proto *tp,
127 				      struct tcf_result *res)
128 {
129 	struct route4_head *head = rcu_dereference_bh(tp->root);
130 	struct dst_entry *dst;
131 	struct route4_bucket *b;
132 	struct route4_filter *f;
133 	u32 id, h;
134 	int iif, dont_cache = 0;
135 
136 	dst = skb_dst(skb);
137 	if (!dst)
138 		goto failure;
139 
140 	id = dst->tclassid;
141 
142 	iif = inet_iif(skb);
143 
144 	h = route4_fastmap_hash(id, iif);
145 
146 	spin_lock(&fastmap_lock);
147 	if (id == head->fastmap[h].id &&
148 	    iif == head->fastmap[h].iif &&
149 	    (f = head->fastmap[h].filter) != NULL) {
150 		if (f == ROUTE4_FAILURE) {
151 			spin_unlock(&fastmap_lock);
152 			goto failure;
153 		}
154 
155 		*res = f->res;
156 		spin_unlock(&fastmap_lock);
157 		return 0;
158 	}
159 	spin_unlock(&fastmap_lock);
160 
161 	h = route4_hash_to(id);
162 
163 restart:
164 	b = rcu_dereference_bh(head->table[h]);
165 	if (b) {
166 		for (f = rcu_dereference_bh(b->ht[route4_hash_from(id)]);
167 		     f;
168 		     f = rcu_dereference_bh(f->next))
169 			if (f->id == id)
170 				ROUTE4_APPLY_RESULT();
171 
172 		for (f = rcu_dereference_bh(b->ht[route4_hash_iif(iif)]);
173 		     f;
174 		     f = rcu_dereference_bh(f->next))
175 			if (f->iif == iif)
176 				ROUTE4_APPLY_RESULT();
177 
178 		for (f = rcu_dereference_bh(b->ht[route4_hash_wild()]);
179 		     f;
180 		     f = rcu_dereference_bh(f->next))
181 			ROUTE4_APPLY_RESULT();
182 	}
183 	if (h < 256) {
184 		h = 256;
185 		id &= ~0xFFFF;
186 		goto restart;
187 	}
188 
189 	if (!dont_cache)
190 		route4_set_fastmap(head, id, iif, ROUTE4_FAILURE);
191 failure:
192 	return -1;
193 }
194 
195 static inline u32 to_hash(u32 id)
196 {
197 	u32 h = id & 0xFF;
198 
199 	if (id & 0x8000)
200 		h += 256;
201 	return h;
202 }
203 
204 static inline u32 from_hash(u32 id)
205 {
206 	id &= 0xFFFF;
207 	if (id == 0xFFFF)
208 		return 32;
209 	if (!(id & 0x8000)) {
210 		if (id > 255)
211 			return 256;
212 		return id & 0xF;
213 	}
214 	return 16 + (id & 0xF);
215 }
216 
217 static void *route4_get(struct tcf_proto *tp, u32 handle)
218 {
219 	struct route4_head *head = rtnl_dereference(tp->root);
220 	struct route4_bucket *b;
221 	struct route4_filter *f;
222 	unsigned int h1, h2;
223 
224 	h1 = to_hash(handle);
225 	if (h1 > 256)
226 		return NULL;
227 
228 	h2 = from_hash(handle >> 16);
229 	if (h2 > 32)
230 		return NULL;
231 
232 	b = rtnl_dereference(head->table[h1]);
233 	if (b) {
234 		for (f = rtnl_dereference(b->ht[h2]);
235 		     f;
236 		     f = rtnl_dereference(f->next))
237 			if (f->handle == handle)
238 				return f;
239 	}
240 	return NULL;
241 }
242 
243 static int route4_init(struct tcf_proto *tp)
244 {
245 	struct route4_head *head;
246 
247 	head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
248 	if (head == NULL)
249 		return -ENOBUFS;
250 
251 	rcu_assign_pointer(tp->root, head);
252 	return 0;
253 }
254 
255 static void __route4_delete_filter(struct route4_filter *f)
256 {
257 	tcf_exts_destroy(&f->exts);
258 	tcf_exts_put_net(&f->exts);
259 	kfree(f);
260 }
261 
262 static void route4_delete_filter_work(struct work_struct *work)
263 {
264 	struct route4_filter *f = container_of(to_rcu_work(work),
265 					       struct route4_filter,
266 					       rwork);
267 	rtnl_lock();
268 	__route4_delete_filter(f);
269 	rtnl_unlock();
270 }
271 
272 static void route4_queue_work(struct route4_filter *f)
273 {
274 	tcf_queue_work(&f->rwork, route4_delete_filter_work);
275 }
276 
277 static void route4_destroy(struct tcf_proto *tp, bool rtnl_held,
278 			   struct netlink_ext_ack *extack)
279 {
280 	struct route4_head *head = rtnl_dereference(tp->root);
281 	int h1, h2;
282 
283 	if (head == NULL)
284 		return;
285 
286 	for (h1 = 0; h1 <= 256; h1++) {
287 		struct route4_bucket *b;
288 
289 		b = rtnl_dereference(head->table[h1]);
290 		if (b) {
291 			for (h2 = 0; h2 <= 32; h2++) {
292 				struct route4_filter *f;
293 
294 				while ((f = rtnl_dereference(b->ht[h2])) != NULL) {
295 					struct route4_filter *next;
296 
297 					next = rtnl_dereference(f->next);
298 					RCU_INIT_POINTER(b->ht[h2], next);
299 					tcf_unbind_filter(tp, &f->res);
300 					if (tcf_exts_get_net(&f->exts))
301 						route4_queue_work(f);
302 					else
303 						__route4_delete_filter(f);
304 				}
305 			}
306 			RCU_INIT_POINTER(head->table[h1], NULL);
307 			kfree_rcu(b, rcu);
308 		}
309 	}
310 	kfree_rcu(head, rcu);
311 }
312 
313 static int route4_delete(struct tcf_proto *tp, void *arg, bool *last,
314 			 bool rtnl_held, struct netlink_ext_ack *extack)
315 {
316 	struct route4_head *head = rtnl_dereference(tp->root);
317 	struct route4_filter *f = arg;
318 	struct route4_filter __rcu **fp;
319 	struct route4_filter *nf;
320 	struct route4_bucket *b;
321 	unsigned int h = 0;
322 	int i, h1;
323 
324 	if (!head || !f)
325 		return -EINVAL;
326 
327 	h = f->handle;
328 	b = f->bkt;
329 
330 	fp = &b->ht[from_hash(h >> 16)];
331 	for (nf = rtnl_dereference(*fp); nf;
332 	     fp = &nf->next, nf = rtnl_dereference(*fp)) {
333 		if (nf == f) {
334 			/* unlink it */
335 			RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
336 
337 			/* Remove any fastmap lookups that might ref filter
338 			 * notice we unlink'd the filter so we can't get it
339 			 * back in the fastmap.
340 			 */
341 			route4_reset_fastmap(head);
342 
343 			/* Delete it */
344 			tcf_unbind_filter(tp, &f->res);
345 			tcf_exts_get_net(&f->exts);
346 			tcf_queue_work(&f->rwork, route4_delete_filter_work);
347 
348 			/* Strip RTNL protected tree */
349 			for (i = 0; i <= 32; i++) {
350 				struct route4_filter *rt;
351 
352 				rt = rtnl_dereference(b->ht[i]);
353 				if (rt)
354 					goto out;
355 			}
356 
357 			/* OK, session has no flows */
358 			RCU_INIT_POINTER(head->table[to_hash(h)], NULL);
359 			kfree_rcu(b, rcu);
360 			break;
361 		}
362 	}
363 
364 out:
365 	*last = true;
366 	for (h1 = 0; h1 <= 256; h1++) {
367 		if (rcu_access_pointer(head->table[h1])) {
368 			*last = false;
369 			break;
370 		}
371 	}
372 
373 	return 0;
374 }
375 
376 static const struct nla_policy route4_policy[TCA_ROUTE4_MAX + 1] = {
377 	[TCA_ROUTE4_CLASSID]	= { .type = NLA_U32 },
378 	[TCA_ROUTE4_TO]		= NLA_POLICY_MAX(NLA_U32, 0xFF),
379 	[TCA_ROUTE4_FROM]	= NLA_POLICY_MAX(NLA_U32, 0xFF),
380 	[TCA_ROUTE4_IIF]	= NLA_POLICY_MAX(NLA_U32, 0x7FFF),
381 };
382 
383 static int route4_set_parms(struct net *net, struct tcf_proto *tp,
384 			    unsigned long base, struct route4_filter *f,
385 			    u32 handle, struct route4_head *head,
386 			    struct nlattr **tb, struct nlattr *est, int new,
387 			    u32 flags, struct netlink_ext_ack *extack)
388 {
389 	u32 id = 0, to = 0, nhandle = 0x8000;
390 	struct route4_filter *fp;
391 	unsigned int h1;
392 	struct route4_bucket *b;
393 	int err;
394 
395 	err = tcf_exts_validate(net, tp, tb, est, &f->exts, flags, extack);
396 	if (err < 0)
397 		return err;
398 
399 	if (tb[TCA_ROUTE4_TO]) {
400 		if (new && handle & 0x8000) {
401 			NL_SET_ERR_MSG(extack, "Invalid handle");
402 			return -EINVAL;
403 		}
404 		to = nla_get_u32(tb[TCA_ROUTE4_TO]);
405 		nhandle = to;
406 	}
407 
408 	if (tb[TCA_ROUTE4_FROM] && tb[TCA_ROUTE4_IIF]) {
409 		NL_SET_ERR_MSG_ATTR(extack, tb[TCA_ROUTE4_FROM],
410 				    "'from' and 'fromif' are mutually exclusive");
411 		return -EINVAL;
412 	}
413 
414 	if (tb[TCA_ROUTE4_FROM]) {
415 		id = nla_get_u32(tb[TCA_ROUTE4_FROM]);
416 		nhandle |= id << 16;
417 	} else if (tb[TCA_ROUTE4_IIF]) {
418 		id = nla_get_u32(tb[TCA_ROUTE4_IIF]);
419 		nhandle |= (id | 0x8000) << 16;
420 	} else
421 		nhandle |= 0xFFFF << 16;
422 
423 	if (handle && new) {
424 		nhandle |= handle & 0x7F00;
425 		if (nhandle != handle) {
426 			NL_SET_ERR_MSG_FMT(extack,
427 					   "Handle mismatch constructed: %x (expected: %x)",
428 					   handle, nhandle);
429 			return -EINVAL;
430 		}
431 	}
432 
433 	if (!nhandle) {
434 		NL_SET_ERR_MSG(extack, "Replacing with handle of 0 is invalid");
435 		return -EINVAL;
436 	}
437 
438 	h1 = to_hash(nhandle);
439 	b = rtnl_dereference(head->table[h1]);
440 	if (!b) {
441 		b = kzalloc(sizeof(struct route4_bucket), GFP_KERNEL);
442 		if (b == NULL)
443 			return -ENOBUFS;
444 
445 		rcu_assign_pointer(head->table[h1], b);
446 	} else {
447 		unsigned int h2 = from_hash(nhandle >> 16);
448 
449 		for (fp = rtnl_dereference(b->ht[h2]);
450 		     fp;
451 		     fp = rtnl_dereference(fp->next))
452 			if (fp->handle == f->handle)
453 				return -EEXIST;
454 	}
455 
456 	if (tb[TCA_ROUTE4_TO])
457 		f->id = to;
458 
459 	if (tb[TCA_ROUTE4_FROM])
460 		f->id = to | id<<16;
461 	else if (tb[TCA_ROUTE4_IIF])
462 		f->iif = id;
463 
464 	f->handle = nhandle;
465 	f->bkt = b;
466 	f->tp = tp;
467 
468 	if (tb[TCA_ROUTE4_CLASSID]) {
469 		f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);
470 		tcf_bind_filter(tp, &f->res, base);
471 	}
472 
473 	return 0;
474 }
475 
476 static int route4_change(struct net *net, struct sk_buff *in_skb,
477 			 struct tcf_proto *tp, unsigned long base, u32 handle,
478 			 struct nlattr **tca, void **arg, u32 flags,
479 			 struct netlink_ext_ack *extack)
480 {
481 	struct route4_head *head = rtnl_dereference(tp->root);
482 	struct route4_filter __rcu **fp;
483 	struct route4_filter *fold, *f1, *pfp, *f = NULL;
484 	struct route4_bucket *b;
485 	struct nlattr *tb[TCA_ROUTE4_MAX + 1];
486 	unsigned int h, th;
487 	int err;
488 	bool new = true;
489 
490 	if (!handle) {
491 		NL_SET_ERR_MSG(extack, "Creating with handle of 0 is invalid");
492 		return -EINVAL;
493 	}
494 
495 	if (NL_REQ_ATTR_CHECK(extack, NULL, tca, TCA_OPTIONS)) {
496 		NL_SET_ERR_MSG_MOD(extack, "Missing options");
497 		return -EINVAL;
498 	}
499 
500 	err = nla_parse_nested_deprecated(tb, TCA_ROUTE4_MAX, tca[TCA_OPTIONS],
501 					  route4_policy, NULL);
502 	if (err < 0)
503 		return err;
504 
505 	fold = *arg;
506 	if (fold && fold->handle != handle)
507 			return -EINVAL;
508 
509 	err = -ENOBUFS;
510 	f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL);
511 	if (!f)
512 		goto errout;
513 
514 	err = tcf_exts_init(&f->exts, net, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);
515 	if (err < 0)
516 		goto errout;
517 
518 	if (fold) {
519 		f->id = fold->id;
520 		f->iif = fold->iif;
521 		f->handle = fold->handle;
522 
523 		f->tp = fold->tp;
524 		f->bkt = fold->bkt;
525 		new = false;
526 	}
527 
528 	err = route4_set_parms(net, tp, base, f, handle, head, tb,
529 			       tca[TCA_RATE], new, flags, extack);
530 	if (err < 0)
531 		goto errout;
532 
533 	h = from_hash(f->handle >> 16);
534 	fp = &f->bkt->ht[h];
535 	for (pfp = rtnl_dereference(*fp);
536 	     (f1 = rtnl_dereference(*fp)) != NULL;
537 	     fp = &f1->next)
538 		if (f->handle < f1->handle)
539 			break;
540 
541 	tcf_block_netif_keep_dst(tp->chain->block);
542 	rcu_assign_pointer(f->next, f1);
543 	rcu_assign_pointer(*fp, f);
544 
545 	if (fold) {
546 		th = to_hash(fold->handle);
547 		h = from_hash(fold->handle >> 16);
548 		b = rtnl_dereference(head->table[th]);
549 		if (b) {
550 			fp = &b->ht[h];
551 			for (pfp = rtnl_dereference(*fp); pfp;
552 			     fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
553 				if (pfp == fold) {
554 					rcu_assign_pointer(*fp, fold->next);
555 					break;
556 				}
557 			}
558 		}
559 	}
560 
561 	route4_reset_fastmap(head);
562 	*arg = f;
563 	if (fold) {
564 		tcf_unbind_filter(tp, &fold->res);
565 		tcf_exts_get_net(&fold->exts);
566 		tcf_queue_work(&fold->rwork, route4_delete_filter_work);
567 	}
568 	return 0;
569 
570 errout:
571 	if (f)
572 		tcf_exts_destroy(&f->exts);
573 	kfree(f);
574 	return err;
575 }
576 
577 static void route4_walk(struct tcf_proto *tp, struct tcf_walker *arg,
578 			bool rtnl_held)
579 {
580 	struct route4_head *head = rtnl_dereference(tp->root);
581 	unsigned int h, h1;
582 
583 	if (head == NULL || arg->stop)
584 		return;
585 
586 	for (h = 0; h <= 256; h++) {
587 		struct route4_bucket *b = rtnl_dereference(head->table[h]);
588 
589 		if (b) {
590 			for (h1 = 0; h1 <= 32; h1++) {
591 				struct route4_filter *f;
592 
593 				for (f = rtnl_dereference(b->ht[h1]);
594 				     f;
595 				     f = rtnl_dereference(f->next)) {
596 					if (!tc_cls_stats_dump(tp, arg, f))
597 						return;
598 				}
599 			}
600 		}
601 	}
602 }
603 
604 static int route4_dump(struct net *net, struct tcf_proto *tp, void *fh,
605 		       struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
606 {
607 	struct route4_filter *f = fh;
608 	struct nlattr *nest;
609 	u32 id;
610 
611 	if (f == NULL)
612 		return skb->len;
613 
614 	t->tcm_handle = f->handle;
615 
616 	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
617 	if (nest == NULL)
618 		goto nla_put_failure;
619 
620 	if (!(f->handle & 0x8000)) {
621 		id = f->id & 0xFF;
622 		if (nla_put_u32(skb, TCA_ROUTE4_TO, id))
623 			goto nla_put_failure;
624 	}
625 	if (f->handle & 0x80000000) {
626 		if ((f->handle >> 16) != 0xFFFF &&
627 		    nla_put_u32(skb, TCA_ROUTE4_IIF, f->iif))
628 			goto nla_put_failure;
629 	} else {
630 		id = f->id >> 16;
631 		if (nla_put_u32(skb, TCA_ROUTE4_FROM, id))
632 			goto nla_put_failure;
633 	}
634 	if (f->res.classid &&
635 	    nla_put_u32(skb, TCA_ROUTE4_CLASSID, f->res.classid))
636 		goto nla_put_failure;
637 
638 	if (tcf_exts_dump(skb, &f->exts) < 0)
639 		goto nla_put_failure;
640 
641 	nla_nest_end(skb, nest);
642 
643 	if (tcf_exts_dump_stats(skb, &f->exts) < 0)
644 		goto nla_put_failure;
645 
646 	return skb->len;
647 
648 nla_put_failure:
649 	nla_nest_cancel(skb, nest);
650 	return -1;
651 }
652 
653 static void route4_bind_class(void *fh, u32 classid, unsigned long cl, void *q,
654 			      unsigned long base)
655 {
656 	struct route4_filter *f = fh;
657 
658 	tc_cls_bind_class(classid, cl, q, &f->res, base);
659 }
660 
661 static struct tcf_proto_ops cls_route4_ops __read_mostly = {
662 	.kind		=	"route",
663 	.classify	=	route4_classify,
664 	.init		=	route4_init,
665 	.destroy	=	route4_destroy,
666 	.get		=	route4_get,
667 	.change		=	route4_change,
668 	.delete		=	route4_delete,
669 	.walk		=	route4_walk,
670 	.dump		=	route4_dump,
671 	.bind_class	=	route4_bind_class,
672 	.owner		=	THIS_MODULE,
673 };
674 
675 static int __init init_route4(void)
676 {
677 	return register_tcf_proto_ops(&cls_route4_ops);
678 }
679 
680 static void __exit exit_route4(void)
681 {
682 	unregister_tcf_proto_ops(&cls_route4_ops);
683 }
684 
685 module_init(init_route4)
686 module_exit(exit_route4)
687 MODULE_DESCRIPTION("Routing table realm based TC classifier");
688 MODULE_LICENSE("GPL");
689