2 * cls_can.c -- Controller Area Network classifier.
3 * Makes decisions according to Controller Area Network identifiers (can_id).
5 * This program is free software; you can distribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; version 2 of
10 * Idea: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
11 * Copyright: (c) 2011 Czech Technical University in Prague
12 * (c) 2011 Volkswagen Group Research
13 * Authors: Michal Sojka <sojkam1@fel.cvut.cz>
14 * Pavel Pisa <pisa@cmp.felk.cvut.cz>
15 * Rostislav Lisovy <lisovy@kormus.cz>
16 * Funded by: Volkswagen Group Research
18 * Some function descriptions are heavily inspired by article "Linux Network
19 * Traffic Control -- Implementation Overview" by Werner Almesberger
22 #include <linux/module.h>
23 #include <linux/slab.h>
24 #include <linux/types.h>
25 #include <linux/kernel.h>
26 #include <linux/string.h>
27 #include <linux/errno.h>
28 #include <linux/rtnetlink.h>
29 #include <linux/skbuff.h>
30 #include <net/netlink.h>
31 #include <net/act_api.h>
32 #include <net/pkt_cls.h>
33 #include <linux/bitmap.h>
34 #include <linux/spinlock.h>
35 #include <linux/rcupdate.h>
36 #include <linux/can.h>
38 #ifndef CAN_SFF_ID_BITS
39 #define CAN_SFF_ID_BITS 11
40 #define CAN_EFF_ID_BITS 29
43 #define SFF_BITMAP 1 /* Use bitmap for storing rules
46 /* Definition of Netlink message parts */
50 TCA_CANFLTR_RULES, /* Array of can_filter structs; We are able
51 to determine the length after receiving */
54 #define TCA_CANFLTR_MAX (__TCA_CANFLTR_MAX - 1)
56 static const struct nla_policy canfltr_policy[TCA_CANFLTR_MAX + 1] = {
57 [TCA_CANFLTR_CLASSID] = { .type = NLA_U32 },
58 /* FIXME Be aware of possible problems with 64bit kernel and
59 32bit userspace etc. */
60 [TCA_CANFLTR_RULES] = { /*.len = (sizeof(struct can_filter))*/ } /* FIXME */
63 struct canfltr_rules {
64 struct can_filter *rules_raw; /* Raw rules copied from netlink
65 message; Used for sending information
66 to userspace (when 'tc filter show' is
67 invoked) AND when matching EFF frames*/
69 DECLARE_BITMAP(match_sff, (1 << CAN_SFF_ID_BITS)); /* For each SFF CAN
70 ID (11 bit) there is one record in this
73 int inv_match_en; /* Inverted match flag */
83 struct list_head flist;
86 struct canfltr_state {
88 struct canfltr_rules *rules; /* All rules necessary for
90 struct tcf_result res; /* Class ID (flow id) the instance
91 of a filter is bound to */
92 struct list_head link;
96 * ----------------------------------------------------------------------------
99 static void canfltr_sff_match_add(struct canfltr_rules *rls,
100 u32 can_id, u32 can_mask)
105 /* Limit can_mask and can_id to SFF range to
106 protect against write after end of array */
107 can_mask &= CAN_SFF_MASK;
111 if (can_mask == CAN_SFF_MASK) {
112 set_bit(can_id, rls->match_sff);
118 bitmap_fill(rls->match_sff, (1 << CAN_SFF_ID_BITS));
122 /* individual frame filter */
123 /* Add record (set bit to 1) for each ID that
124 conforms particular rule */
125 for (i = 0; i < (1 << CAN_SFF_ID_BITS); i++) {
126 if ((i & can_mask) == can_id)
127 set_bit(i, rls->match_sff);
133 * Extracts Can ID out of the sk_buff structure.
135 static canid_t canfltr_get_id(struct sk_buff *skb)
137 /* Can ID is inside of data field */
138 struct can_frame *cf = (struct can_frame *)skb->data;
144 * Performs the classification. Iterates over all instances of filter,
145 * checking for CAN ID match.
147 * @skb: Socket buffer
149 * @res: Is used for setting Class ID as a result of classification
151 * Returns value relevant for policing. Used return values:
152 * TC_POLICE_OK if succesfully classified (without regard to policing rules)
153 * TC_POLICE_UNSPEC if no matching rule was found
155 static int canfltr_classify(struct sk_buff *skb, struct tcf_proto *tp,
156 struct tcf_result *res)
158 struct canfltr_head *head = (struct canfltr_head *)tp->root;
159 struct canfltr_state *f;
160 struct canfltr_rules *r;
164 can_id = canfltr_get_id(skb);
167 list_for_each_entry(f, &head->flist, link) {
169 r = rcu_dereference(f->rules);
172 if (can_id & CAN_EFF_FLAG) {
173 can_id &= CAN_EFF_MASK;
175 for (i = 0; i < r->eff_rules_count; i++) {
176 /* XXX: Why aren't these & performed "off-line"? */
177 if ((r->rules_raw[i].can_id & r->rules_raw[i].can_mask & CAN_EFF_MASK) ==
178 (can_id & r->rules_raw[i].can_mask & CAN_EFF_MASK)) {
184 can_id &= CAN_SFF_MASK;
186 match = test_bit(can_id, r->match_sff);
188 for (i = r->eff_rules_count; i < r->eff_rules_count + r->sff_rules_count; i++) {
189 if ((r->rules_raw[i].can_id & r->rules_raw[i].can_mask & CAN_SFF_MASK) == /* XXX: dtto */
190 (can_id & r->rules_raw[i].can_mask & CAN_SFF_MASK)) {
206 return TC_POLICE_UNSPEC;
210 * Looks up a filter element by its handle and returns the internal
211 * filter ID (i.e. pointer)
213 static unsigned long canfltr_get(struct tcf_proto *tp, u32 handle)
215 struct canfltr_head *head = (struct canfltr_head *)tp->root;
216 struct canfltr_state *f;
221 list_for_each_entry(f, &head->flist, link) {
222 if (f->handle == handle)
223 return (unsigned long) f;
230 * Is invoked when a filter element previously referenced
231 * with get() is no longer used
233 static void canfltr_put(struct tcf_proto *tp, unsigned long f)
237 static unsigned int canfltr_gen_handle(struct tcf_proto *tp)
239 struct canfltr_head *head = (struct canfltr_head *)tp->root;
245 head->hgenerator += 0x10000;
246 if (head->hgenerator == 0)
247 head->hgenerator = 0x10000;
249 h = head->hgenerator;
250 if (canfltr_get(tp, h) == 0)
256 static void canfltr_rules_free_rcu(struct rcu_head *rcu)
258 kfree(container_of(rcu, struct canfltr_rules, rcu));
261 static int canfltr_set_parms(struct tcf_proto *tp, struct canfltr_state *f,
262 unsigned long base, struct nlattr **tb,
265 struct can_filter *canfltr_nl_rules;
266 struct canfltr_rules *rules_tmp;
270 rules_tmp = kzalloc(sizeof(*rules_tmp), GFP_KERNEL);
271 if (rules_tmp == NULL)
272 return -ENOBUFS; /* XXX: Why not -ENOMEM? */
275 if (tb[TCA_CANFLTR_CLASSID] == NULL)
278 if (tb[TCA_CANFLTR_RULES]) {
279 canfltr_nl_rules = nla_data(tb[TCA_CANFLTR_RULES]);
280 rules_tmp->sff_rules_count = 0;
281 rules_tmp->eff_rules_count = 0;
282 rules_tmp->rules_count = (nla_len(tb[TCA_CANFLTR_RULES]) /
283 sizeof(struct can_filter));
285 rules_tmp->rules_raw = kzalloc(sizeof(struct can_filter) *
286 rules_tmp->rules_count, GFP_KERNEL);
288 if (rules_tmp->rules_raw == NULL)
291 /* We need two for() loops for copying rules into
292 two contiguous areas in rules_raw */
294 /* Process EFF frame rules*/
295 for (i = 0; i < rules_tmp->rules_count; i++) {
296 if ((canfltr_nl_rules[i].can_id & CAN_EFF_FLAG) &&
297 (canfltr_nl_rules[i].can_mask & CAN_EFF_FLAG)) {
298 memcpy(rules_tmp->rules_raw +
299 rules_tmp->eff_rules_count,
300 &canfltr_nl_rules[i],
301 sizeof(struct can_filter));
302 rules_tmp->eff_rules_count++;
308 /* Process SFF frame rules */
309 for (i = 0; i < rules_tmp->rules_count; i++) {
310 if ((canfltr_nl_rules[i].can_id & CAN_EFF_FLAG) &&
311 (canfltr_nl_rules[i].can_mask & CAN_EFF_FLAG)) {
314 memcpy(rules_tmp->rules_raw +
315 rules_tmp->eff_rules_count +
316 rules_tmp->sff_rules_count,
317 &canfltr_nl_rules[i],
318 sizeof(struct can_filter));
319 rules_tmp->sff_rules_count++;
320 canfltr_sff_match_add(rules_tmp,
321 canfltr_nl_rules[i].can_id,
322 canfltr_nl_rules[i].can_mask);
328 /* Setting parameters for newly created filter */
329 if (f->rules == NULL) {
330 rcu_assign_pointer(f->rules, rules_tmp);
331 } else { /* Changing existing filter */
332 struct canfltr_rules *rules_old;
334 rules_old = xchg(&f->rules, rules_tmp);
335 call_rcu(&rules_old->rcu, canfltr_rules_free_rcu);
346 * Called for changing properties of an existing filter or after addition
347 * of a new filter to a class (by calling bind_tcf which binds an instance
348 * of a filter to the class).
350 * @tp: Structure representing instance of a filter.
351 * Part of a linked list of all filters.
354 * @tca: Messages passed through the Netlink from userspace.
357 static int canfltr_change(struct tcf_proto *tp, unsigned long base, u32 handle,
358 struct nlattr **tca, unsigned long *arg)
360 struct canfltr_head *head = (struct canfltr_head *)tp->root;
361 struct canfltr_state *f = (struct canfltr_state *)*arg;
362 struct nlattr *tb[TCA_CANFLTR_MAX + 1];
365 if (tca[TCA_OPTIONS] == NULL)
368 /* Parses a stream of attributes and stores a pointer to each
369 attribute in the tb array accessible via the attribute type.
370 Policy may be set to NULL if no validation is required.*/
371 err = nla_parse_nested(tb, TCA_CANFLTR_MAX, tca[TCA_OPTIONS],
375 /* Change existing filter (remove all settings and add
376 them thereafter as if filter was newly created) */
378 if (handle && f->handle != handle)
381 return canfltr_set_parms(tp, f, base, tb, tca[TCA_RATE]);
384 /* Create new filter */
386 f = kzalloc(sizeof(*f), GFP_KERNEL);
390 if (tb[TCA_CANFLTR_CLASSID]) {
391 f->res.classid = nla_get_u32(tb[TCA_U32_CLASSID]);
392 tcf_bind_filter(tp, &f->res, base);
396 if (handle) /* handle passed from userspace */
399 f->handle = canfltr_gen_handle(tp);
402 /* Configure filter */
403 err = canfltr_set_parms(tp, f, base, tb, tca[TCA_RATE]);
407 /* Add newly created filter to list of all filters */
409 list_add(&f->link, &head->flist);
411 *arg = (unsigned long) f;
416 if (*arg == 0UL && f)
423 static void canfltr_delete_filter(struct tcf_proto *tp,
424 struct canfltr_state *f)
426 tcf_unbind_filter(tp, &f->res);
429 kfree(f->rules->rules_raw);
435 * Remove whole filter.
437 static void canfltr_destroy(struct tcf_proto *tp)
439 struct canfltr_head *head = tp->root;
440 struct canfltr_state *f, *n;
442 list_for_each_entry_safe(f, n, &head->flist, link) {
444 canfltr_delete_filter(tp, f);
450 * Delete one instance of a filter.
452 static int canfltr_delete(struct tcf_proto *tp, unsigned long arg)
454 struct canfltr_head *head = (struct canfltr_head *)tp->root;
455 struct canfltr_state *t;
456 struct canfltr_state *f = (struct canfltr_state *)arg;
458 rcu_barrier(); /* Wait for completion of call_rcu()'s */
460 list_for_each_entry(t, &head->flist, link)
465 canfltr_delete_filter(tp, t);
476 static int canfltr_init(struct tcf_proto *tp)
478 struct canfltr_head *head;
480 head = kzalloc(sizeof(*head), GFP_KERNEL);
484 INIT_LIST_HEAD(&head->flist);
486 tp->protocol = htons(ETH_P_CAN); /* Work only on AF_CAN packets - not tested! */
492 * Iterates over all elements of a filter and invokes a callback function
493 * for each of them. This is used to obtain diagnostic data
495 static void canfltr_walk(struct tcf_proto *tp, struct tcf_walker *arg)
497 struct canfltr_head *head = (struct canfltr_head *) tp->root;
498 struct canfltr_state *f;
500 list_for_each_entry(f, &head->flist, link) {
501 if (arg->count < arg->skip)
504 if (arg->fn(tp, (unsigned long) f, arg) < 0) {
514 * Returns diagnostic data for a filter or one of its elements.
516 static int canfltr_dump(struct tcf_proto *tp, unsigned long fh,
517 struct sk_buff *skb, struct tcmsg *t)
519 struct canfltr_state *f = (struct canfltr_state *) fh;
521 struct canfltr_rules *r;
527 r = rcu_dereference(f->rules);
528 t->tcm_handle = f->handle;
530 nest = nla_nest_start(skb, TCA_OPTIONS);
532 goto nla_put_failure;
535 NLA_PUT_U32(skb, TCA_CANFLTR_CLASSID, f->res.classid);
537 NLA_PUT(skb, TCA_CANFLTR_RULES, r->rules_count *
538 sizeof(struct can_filter), r->rules_raw);
541 nla_nest_end(skb, nest);
547 nla_nest_cancel(skb, nest);
553 static struct tcf_proto_ops cls_canfltr_ops __read_mostly = {
555 .classify = canfltr_classify,
556 .init = canfltr_init,
557 .destroy = canfltr_destroy,
560 .change = canfltr_change,
561 .delete = canfltr_delete,
562 .walk = canfltr_walk,
563 .dump = canfltr_dump,
564 .owner = THIS_MODULE,
567 static int __init init_canfltr(void)
569 pr_debug("canfltr: CAN filter loaded\n");
571 pr_debug("canfltr: SFF rules stored in bitmap\n");
573 pr_debug("canfltr: SFF rules stored in array\n");
575 return register_tcf_proto_ops(&cls_canfltr_ops);
578 static void __exit exit_canfltr(void)
580 pr_debug("canfltr: CAN filter removed\n");
581 unregister_tcf_proto_ops(&cls_canfltr_ops);
584 module_init(init_canfltr);
585 module_exit(exit_canfltr);
586 MODULE_LICENSE("GPL");
587 MODULE_AUTHOR(""); /* FIXME */
588 MODULE_DESCRIPTION("Controller Area Network classifier");