1/*
2 * net/sched/cls_tcindex.c	Packet classifier for skb->tc_index
3 *
4 * Written 1998,1999 by Werner Almesberger, EPFL ICA
5 */
6
7#include <linux/module.h>
8#include <linux/types.h>
9#include <linux/kernel.h>
10#include <linux/skbuff.h>
11#include <linux/errno.h>
12#include <linux/slab.h>
13#include <net/act_api.h>
14#include <net/netlink.h>
15#include <net/pkt_cls.h>
16
17/*
18 * Passing parameters to the root seems to be done more awkwardly than really
19 * necessary. At least, u32 doesn't seem to use such dirty hacks. To be
20 * verified. FIXME.
21 */
22
23#define PERFECT_HASH_THRESHOLD	64	/* use perfect hash if not bigger */
24#define DEFAULT_HASH_SIZE	64	/* optimized for diffserv */
25
26
27struct tcindex_filter_result {
28	struct tcf_exts		exts;
29	struct tcf_result	res;
30};
31
32struct tcindex_filter {
33	u16 key;
34	struct tcindex_filter_result result;
35	struct tcindex_filter __rcu *next;
36	struct rcu_head rcu;
37};
38
39
40struct tcindex_data {
41	struct tcindex_filter_result *perfect; /* perfect hash; NULL if none */
42	struct tcindex_filter __rcu **h; /* imperfect hash; */
43	struct tcf_proto *tp;
44	u16 mask;		/* AND key with mask */
45	u32 shift;		/* shift ANDed key to the right */
46	u32 hash;		/* hash table size; 0 if undefined */
47	u32 alloc_hash;		/* allocated size */
48	u32 fall_through;	/* 0: only classify if explicit match */
49	struct rcu_head rcu;
50};
51
52static inline int
53tcindex_filter_is_set(struct tcindex_filter_result *r)
54{
55	return tcf_exts_is_predicative(&r->exts) || r->res.classid;
56}
57
58static struct tcindex_filter_result *
59tcindex_lookup(struct tcindex_data *p, u16 key)
60{
61	if (p->perfect) {
62		struct tcindex_filter_result *f = p->perfect + key;
63
64		return tcindex_filter_is_set(f) ? f : NULL;
65	} else if (p->h) {
66		struct tcindex_filter __rcu **fp;
67		struct tcindex_filter *f;
68
69		fp = &p->h[key % p->hash];
70		for (f = rcu_dereference_bh_rtnl(*fp);
71		     f;
72		     fp = &f->next, f = rcu_dereference_bh_rtnl(*fp))
73			if (f->key == key)
74				return &f->result;
75	}
76
77	return NULL;
78}
79
80
81static int tcindex_classify(struct sk_buff *skb, const struct tcf_proto *tp,
82			    struct tcf_result *res)
83{
84	struct tcindex_data *p = rcu_dereference_bh(tp->root);
85	struct tcindex_filter_result *f;
86	int key = (skb->tc_index & p->mask) >> p->shift;
87
88	pr_debug("tcindex_classify(skb %p,tp %p,res %p),p %p\n",
89		 skb, tp, res, p);
90
91	f = tcindex_lookup(p, key);
92	if (!f) {
93		if (!p->fall_through)
94			return -1;
95		res->classid = TC_H_MAKE(TC_H_MAJ(tp->q->handle), key);
96		res->class = 0;
97		pr_debug("alg 0x%x\n", res->classid);
98		return 0;
99	}
100	*res = f->res;
101	pr_debug("map 0x%x\n", res->classid);
102
103	return tcf_exts_exec(skb, &f->exts, res);
104}
105
106
107static unsigned long tcindex_get(struct tcf_proto *tp, u32 handle)
108{
109	struct tcindex_data *p = rtnl_dereference(tp->root);
110	struct tcindex_filter_result *r;
111
112	pr_debug("tcindex_get(tp %p,handle 0x%08x)\n", tp, handle);
113	if (p->perfect && handle >= p->alloc_hash)
114		return 0;
115	r = tcindex_lookup(p, handle);
116	return r && tcindex_filter_is_set(r) ? (unsigned long) r : 0UL;
117}
118
119static int tcindex_init(struct tcf_proto *tp)
120{
121	struct tcindex_data *p;
122
123	pr_debug("tcindex_init(tp %p)\n", tp);
124	p = kzalloc(sizeof(struct tcindex_data), GFP_KERNEL);
125	if (!p)
126		return -ENOMEM;
127
128	p->mask = 0xffff;
129	p->hash = DEFAULT_HASH_SIZE;
130	p->fall_through = 1;
131
132	rcu_assign_pointer(tp->root, p);
133	return 0;
134}
135
136static int
137tcindex_delete(struct tcf_proto *tp, unsigned long arg)
138{
139	struct tcindex_data *p = rtnl_dereference(tp->root);
140	struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
141	struct tcindex_filter __rcu **walk;
142	struct tcindex_filter *f = NULL;
143
144	pr_debug("tcindex_delete(tp %p,arg 0x%lx),p %p\n", tp, arg, p);
145	if (p->perfect) {
146		if (!r->res.class)
147			return -ENOENT;
148	} else {
149		int i;
150
151		for (i = 0; i < p->hash; i++) {
152			walk = p->h + i;
153			for (f = rtnl_dereference(*walk); f;
154			     walk = &f->next, f = rtnl_dereference(*walk)) {
155				if (&f->result == r)
156					goto found;
157			}
158		}
159		return -ENOENT;
160
161found:
162		rcu_assign_pointer(*walk, rtnl_dereference(f->next));
163	}
164	tcf_unbind_filter(tp, &r->res);
165	tcf_exts_destroy(&r->exts);
166	if (f)
167		kfree_rcu(f, rcu);
168	return 0;
169}
170
171static int tcindex_destroy_element(struct tcf_proto *tp,
172				   unsigned long arg,
173				   struct tcf_walker *walker)
174{
175	return tcindex_delete(tp, arg);
176}
177
178static void __tcindex_destroy(struct rcu_head *head)
179{
180	struct tcindex_data *p = container_of(head, struct tcindex_data, rcu);
181
182	kfree(p->perfect);
183	kfree(p->h);
184	kfree(p);
185}
186
187static inline int
188valid_perfect_hash(struct tcindex_data *p)
189{
190	return  p->hash > (p->mask >> p->shift);
191}
192
193static const struct nla_policy tcindex_policy[TCA_TCINDEX_MAX + 1] = {
194	[TCA_TCINDEX_HASH]		= { .type = NLA_U32 },
195	[TCA_TCINDEX_MASK]		= { .type = NLA_U16 },
196	[TCA_TCINDEX_SHIFT]		= { .type = NLA_U32 },
197	[TCA_TCINDEX_FALL_THROUGH]	= { .type = NLA_U32 },
198	[TCA_TCINDEX_CLASSID]		= { .type = NLA_U32 },
199};
200
201static void tcindex_filter_result_init(struct tcindex_filter_result *r)
202{
203	memset(r, 0, sizeof(*r));
204	tcf_exts_init(&r->exts, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
205}
206
207static void __tcindex_partial_destroy(struct rcu_head *head)
208{
209	struct tcindex_data *p = container_of(head, struct tcindex_data, rcu);
210
211	kfree(p->perfect);
212	kfree(p);
213}
214
215static int
216tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
217		  u32 handle, struct tcindex_data *p,
218		  struct tcindex_filter_result *r, struct nlattr **tb,
219		  struct nlattr *est, bool ovr)
220{
221	int err, balloc = 0;
222	struct tcindex_filter_result new_filter_result, *old_r = r;
223	struct tcindex_filter_result cr;
224	struct tcindex_data *cp, *oldp;
225	struct tcindex_filter *f = NULL; /* make gcc behave */
226	struct tcf_exts e;
227
228	tcf_exts_init(&e, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
229	err = tcf_exts_validate(net, tp, tb, est, &e, ovr);
230	if (err < 0)
231		return err;
232
233	err = -ENOMEM;
234	/* tcindex_data attributes must look atomic to classifier/lookup so
235	 * allocate new tcindex data and RCU assign it onto root. Keeping
236	 * perfect hash and hash pointers from old data.
237	 */
238	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
239	if (!cp)
240		goto errout;
241
242	cp->mask = p->mask;
243	cp->shift = p->shift;
244	cp->hash = p->hash;
245	cp->alloc_hash = p->alloc_hash;
246	cp->fall_through = p->fall_through;
247	cp->tp = tp;
248
249	if (p->perfect) {
250		int i;
251
252		cp->perfect = kmemdup(p->perfect,
253				      sizeof(*r) * cp->hash, GFP_KERNEL);
254		if (!cp->perfect)
255			goto errout;
256		for (i = 0; i < cp->hash; i++)
257			tcf_exts_init(&cp->perfect[i].exts,
258				      TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
259		balloc = 1;
260	}
261	cp->h = p->h;
262
263	tcindex_filter_result_init(&new_filter_result);
264	tcindex_filter_result_init(&cr);
265	if (old_r)
266		cr.res = r->res;
267
268	if (tb[TCA_TCINDEX_HASH])
269		cp->hash = nla_get_u32(tb[TCA_TCINDEX_HASH]);
270
271	if (tb[TCA_TCINDEX_MASK])
272		cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);
273
274	if (tb[TCA_TCINDEX_SHIFT])
275		cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
276
277	err = -EBUSY;
278
279	/* Hash already allocated, make sure that we still meet the
280	 * requirements for the allocated hash.
281	 */
282	if (cp->perfect) {
283		if (!valid_perfect_hash(cp) ||
284		    cp->hash > cp->alloc_hash)
285			goto errout_alloc;
286	} else if (cp->h && cp->hash != cp->alloc_hash) {
287		goto errout_alloc;
288	}
289
290	err = -EINVAL;
291	if (tb[TCA_TCINDEX_FALL_THROUGH])
292		cp->fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
293
294	if (!cp->hash) {
295		/* Hash not specified, use perfect hash if the upper limit
296		 * of the hashing index is below the threshold.
297		 */
298		if ((cp->mask >> cp->shift) < PERFECT_HASH_THRESHOLD)
299			cp->hash = (cp->mask >> cp->shift) + 1;
300		else
301			cp->hash = DEFAULT_HASH_SIZE;
302	}
303
304	if (!cp->perfect && !cp->h)
305		cp->alloc_hash = cp->hash;
306
307	/* Note: this could be as restrictive as if (handle & ~(mask >> shift))
308	 * but then, we'd fail handles that may become valid after some future
309	 * mask change. While this is extremely unlikely to ever matter,
310	 * the check below is safer (and also more backwards-compatible).
311	 */
312	if (cp->perfect || valid_perfect_hash(cp))
313		if (handle >= cp->alloc_hash)
314			goto errout_alloc;
315
316
317	err = -ENOMEM;
318	if (!cp->perfect && !cp->h) {
319		if (valid_perfect_hash(cp)) {
320			int i;
321
322			cp->perfect = kcalloc(cp->hash, sizeof(*r), GFP_KERNEL);
323			if (!cp->perfect)
324				goto errout_alloc;
325			for (i = 0; i < cp->hash; i++)
326				tcf_exts_init(&cp->perfect[i].exts,
327					      TCA_TCINDEX_ACT,
328					      TCA_TCINDEX_POLICE);
329			balloc = 1;
330		} else {
331			struct tcindex_filter __rcu **hash;
332
333			hash = kcalloc(cp->hash,
334				       sizeof(struct tcindex_filter *),
335				       GFP_KERNEL);
336
337			if (!hash)
338				goto errout_alloc;
339
340			cp->h = hash;
341			balloc = 2;
342		}
343	}
344
345	if (cp->perfect)
346		r = cp->perfect + handle;
347	else
348		r = tcindex_lookup(cp, handle) ? : &new_filter_result;
349
350	if (r == &new_filter_result) {
351		f = kzalloc(sizeof(*f), GFP_KERNEL);
352		if (!f)
353			goto errout_alloc;
354		f->key = handle;
355		tcindex_filter_result_init(&f->result);
356		f->next = NULL;
357	}
358
359	if (tb[TCA_TCINDEX_CLASSID]) {
360		cr.res.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
361		tcf_bind_filter(tp, &cr.res, base);
362	}
363
364	if (old_r)
365		tcf_exts_change(tp, &r->exts, &e);
366	else
367		tcf_exts_change(tp, &cr.exts, &e);
368
369	if (old_r && old_r != r)
370		tcindex_filter_result_init(old_r);
371
372	oldp = p;
373	r->res = cr.res;
374	rcu_assign_pointer(tp->root, cp);
375
376	if (r == &new_filter_result) {
377		struct tcindex_filter *nfp;
378		struct tcindex_filter __rcu **fp;
379
380		tcf_exts_change(tp, &f->result.exts, &r->exts);
381
382		fp = cp->h + (handle % cp->hash);
383		for (nfp = rtnl_dereference(*fp);
384		     nfp;
385		     fp = &nfp->next, nfp = rtnl_dereference(*fp))
386				; /* nothing */
387
388		rcu_assign_pointer(*fp, f);
389	}
390
391	if (oldp)
392		call_rcu(&oldp->rcu, __tcindex_partial_destroy);
393	return 0;
394
395errout_alloc:
396	if (balloc == 1)
397		kfree(cp->perfect);
398	else if (balloc == 2)
399		kfree(cp->h);
400errout:
401	kfree(cp);
402	tcf_exts_destroy(&e);
403	return err;
404}
405
406static int
407tcindex_change(struct net *net, struct sk_buff *in_skb,
408	       struct tcf_proto *tp, unsigned long base, u32 handle,
409	       struct nlattr **tca, unsigned long *arg, bool ovr)
410{
411	struct nlattr *opt = tca[TCA_OPTIONS];
412	struct nlattr *tb[TCA_TCINDEX_MAX + 1];
413	struct tcindex_data *p = rtnl_dereference(tp->root);
414	struct tcindex_filter_result *r = (struct tcindex_filter_result *) *arg;
415	int err;
416
417	pr_debug("tcindex_change(tp %p,handle 0x%08x,tca %p,arg %p),opt %p,"
418	    "p %p,r %p,*arg 0x%lx\n",
419	    tp, handle, tca, arg, opt, p, r, arg ? *arg : 0L);
420
421	if (!opt)
422		return 0;
423
424	err = nla_parse_nested(tb, TCA_TCINDEX_MAX, opt, tcindex_policy);
425	if (err < 0)
426		return err;
427
428	return tcindex_set_parms(net, tp, base, handle, p, r, tb,
429				 tca[TCA_RATE], ovr);
430}
431
432static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
433{
434	struct tcindex_data *p = rtnl_dereference(tp->root);
435	struct tcindex_filter *f, *next;
436	int i;
437
438	pr_debug("tcindex_walk(tp %p,walker %p),p %p\n", tp, walker, p);
439	if (p->perfect) {
440		for (i = 0; i < p->hash; i++) {
441			if (!p->perfect[i].res.class)
442				continue;
443			if (walker->count >= walker->skip) {
444				if (walker->fn(tp,
445				    (unsigned long) (p->perfect+i), walker)
446				     < 0) {
447					walker->stop = 1;
448					return;
449				}
450			}
451			walker->count++;
452		}
453	}
454	if (!p->h)
455		return;
456	for (i = 0; i < p->hash; i++) {
457		for (f = rtnl_dereference(p->h[i]); f; f = next) {
458			next = rtnl_dereference(f->next);
459			if (walker->count >= walker->skip) {
460				if (walker->fn(tp, (unsigned long) &f->result,
461				    walker) < 0) {
462					walker->stop = 1;
463					return;
464				}
465			}
466			walker->count++;
467		}
468	}
469}
470
471static bool tcindex_destroy(struct tcf_proto *tp, bool force)
472{
473	struct tcindex_data *p = rtnl_dereference(tp->root);
474	struct tcf_walker walker;
475
476	if (!force)
477		return false;
478
479	pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
480	walker.count = 0;
481	walker.skip = 0;
482	walker.fn = tcindex_destroy_element;
483	tcindex_walk(tp, &walker);
484
485	RCU_INIT_POINTER(tp->root, NULL);
486	call_rcu(&p->rcu, __tcindex_destroy);
487	return true;
488}
489
490
491static int tcindex_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
492    struct sk_buff *skb, struct tcmsg *t)
493{
494	struct tcindex_data *p = rtnl_dereference(tp->root);
495	struct tcindex_filter_result *r = (struct tcindex_filter_result *) fh;
496	struct nlattr *nest;
497
498	pr_debug("tcindex_dump(tp %p,fh 0x%lx,skb %p,t %p),p %p,r %p\n",
499		 tp, fh, skb, t, p, r);
500	pr_debug("p->perfect %p p->h %p\n", p->perfect, p->h);
501
502	nest = nla_nest_start(skb, TCA_OPTIONS);
503	if (nest == NULL)
504		goto nla_put_failure;
505
506	if (!fh) {
507		t->tcm_handle = ~0; /* whatever ... */
508		if (nla_put_u32(skb, TCA_TCINDEX_HASH, p->hash) ||
509		    nla_put_u16(skb, TCA_TCINDEX_MASK, p->mask) ||
510		    nla_put_u32(skb, TCA_TCINDEX_SHIFT, p->shift) ||
511		    nla_put_u32(skb, TCA_TCINDEX_FALL_THROUGH, p->fall_through))
512			goto nla_put_failure;
513		nla_nest_end(skb, nest);
514	} else {
515		if (p->perfect) {
516			t->tcm_handle = r - p->perfect;
517		} else {
518			struct tcindex_filter *f;
519			struct tcindex_filter __rcu **fp;
520			int i;
521
522			t->tcm_handle = 0;
523			for (i = 0; !t->tcm_handle && i < p->hash; i++) {
524				fp = &p->h[i];
525				for (f = rtnl_dereference(*fp);
526				     !t->tcm_handle && f;
527				     fp = &f->next, f = rtnl_dereference(*fp)) {
528					if (&f->result == r)
529						t->tcm_handle = f->key;
530				}
531			}
532		}
533		pr_debug("handle = %d\n", t->tcm_handle);
534		if (r->res.class &&
535		    nla_put_u32(skb, TCA_TCINDEX_CLASSID, r->res.classid))
536			goto nla_put_failure;
537
538		if (tcf_exts_dump(skb, &r->exts) < 0)
539			goto nla_put_failure;
540		nla_nest_end(skb, nest);
541
542		if (tcf_exts_dump_stats(skb, &r->exts) < 0)
543			goto nla_put_failure;
544	}
545
546	return skb->len;
547
548nla_put_failure:
549	nla_nest_cancel(skb, nest);
550	return -1;
551}
552
553static struct tcf_proto_ops cls_tcindex_ops __read_mostly = {
554	.kind		=	"tcindex",
555	.classify	=	tcindex_classify,
556	.init		=	tcindex_init,
557	.destroy	=	tcindex_destroy,
558	.get		=	tcindex_get,
559	.change		=	tcindex_change,
560	.delete		=	tcindex_delete,
561	.walk		=	tcindex_walk,
562	.dump		=	tcindex_dump,
563	.owner		=	THIS_MODULE,
564};
565
566static int __init init_tcindex(void)
567{
568	return register_tcf_proto_ops(&cls_tcindex_ops);
569}
570
571static void __exit exit_tcindex(void)
572{
573	unregister_tcf_proto_ops(&cls_tcindex_ops);
574}
575
576module_init(init_tcindex)
577module_exit(exit_tcindex)
578MODULE_LICENSE("GPL");
579