2 * em_canid.c Ematch rule to match CAN frames according to their CAN IDs
4 * This program is free software; you can distribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
9 * Idea: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
10 * Copyright: (c) 2011 Czech Technical University in Prague
11 * (c) 2011 Volkswagen Group Research
12 * Authors: Michal Sojka <sojkam1@fel.cvut.cz>
13 * Pavel Pisa <pisa@cmp.felk.cvut.cz>
14 * Rostislav Lisovy <lisovy@gmail.cz>
15 * Funded by: Volkswagen Group Research
18 #include <linux/slab.h>
19 #include <linux/module.h>
20 #include <linux/types.h>
21 #include <linux/kernel.h>
22 #include <linux/string.h>
23 #include <linux/skbuff.h>
24 #include <net/pkt_cls.h>
25 #include <linux/can.h>
27 #define EM_CAN_RULES_MAX 500
30 /* For each SFF CAN ID (11 bit) there is one record in this bitfield */
31 DECLARE_BITMAP(match_sff, (1 << CAN_SFF_ID_BITS));
38 * Raw rules copied from netlink message; Used for sending
39 * information to userspace (when 'tc filter show' is invoked)
40 * AND when matching EFF frames
42 struct can_filter rules_raw[];
46 * em_canid_get_id() - Extracts Can ID out of the sk_buff structure.
48 static canid_t em_canid_get_id(struct sk_buff *skb)
50 /* CAN ID is stored within the data field */
51 struct can_frame *cf = (struct can_frame *)skb->data;
56 static void em_canid_sff_match_add(struct canid_match *cm, u32 can_id,
62 * Limit can_mask and can_id to SFF range to
63 * protect against write after end of array
65 can_mask &= CAN_SFF_MASK;
69 if (can_mask == CAN_SFF_MASK) {
70 set_bit(can_id, cm->match_sff);
76 bitmap_fill(cm->match_sff, (1 << CAN_SFF_ID_BITS));
81 * Individual frame filter.
82 * Add record (set bit to 1) for each ID that
83 * conforms particular rule
85 for (i = 0; i < (1 << CAN_SFF_ID_BITS); i++) {
86 if ((i & can_mask) == can_id)
87 set_bit(i, cm->match_sff);
91 static inline struct canid_match *em_canid_priv(struct tcf_ematch *m)
93 return (struct canid_match *) m->data;
96 static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m,
97 struct tcf_pkt_info *info)
99 struct canid_match *cm = em_canid_priv(m);
101 unsigned int match = false;
104 can_id = em_canid_get_id(skb);
106 if (can_id & CAN_EFF_FLAG) {
107 can_id &= CAN_EFF_MASK;
109 for (i = 0; i < cm->eff_rules_count; i++) {
110 if (!(((cm->rules_raw[i].can_id ^ can_id) &
111 cm->rules_raw[i].can_mask) & CAN_EFF_MASK)) {
117 can_id &= CAN_SFF_MASK;
118 match = test_bit(can_id, cm->match_sff);
127 static int em_canid_change(struct tcf_proto *tp, void *data, int len,
128 struct tcf_ematch *m)
130 struct can_filter *conf = data; /* Array with rules,
131 * fixed size EM_CAN_RULES_SIZE
133 struct canid_match *cm;
134 struct canid_match *cm_old = (struct canid_match *) m->data;
139 if (len < sizeof(struct can_filter))
142 rulescnt = len / sizeof(struct can_filter);
145 cm = kzalloc(sizeof(struct canid_match) + sizeof(struct can_filter) *
146 rulescnt, GFP_KERNEL);
150 cm->sff_rules_count = 0;
151 cm->eff_rules_count = 0;
152 cm->rules_count = rulescnt;
155 /* Be sure to fit into the array */
156 if (cm->rules_count > EM_CAN_RULES_MAX)
160 * We need two for() loops for copying rules into
161 * two contiguous areas in rules_raw
164 /* Process EFF frame rules*/
165 for (i = 0; i < cm->rules_count; i++) {
166 if ((conf[i].can_id & CAN_EFF_FLAG) &&
167 (conf[i].can_mask & CAN_EFF_FLAG)) {
168 memcpy(cm->rules_raw + cm->eff_rules_count,
170 sizeof(struct can_filter));
172 cm->eff_rules_count++;
178 /* Process SFF frame rules */
179 for (i = 0; i < cm->rules_count; i++) {
180 if ((conf[i].can_id & CAN_EFF_FLAG) &&
181 (conf[i].can_mask & CAN_EFF_FLAG)) {
185 + cm->eff_rules_count
186 + cm->sff_rules_count,
187 &conf[i], sizeof(struct can_filter));
189 cm->sff_rules_count++;
191 em_canid_sff_match_add(cm,
192 conf[i].can_id, conf[i].can_mask);
196 m->datalen = sizeof(*cm);
197 m->data = (unsigned long) cm;
199 if (cm_old != NULL) {
200 printk("canid: Configuring an existing ematch!\n");
212 static void em_canid_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
214 struct canid_match *cm = em_canid_priv(m);
219 static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m)
221 struct canid_match *cm = em_canid_priv(m);
224 * When configuring this ematch 'rules_count' is set not to exceed
225 * 'rules_raw' array size
227 if (nla_put_nohdr(skb, sizeof(cm->rules_raw[0]) * cm->rules_count,
229 goto nla_put_failure;
237 static struct tcf_ematch_ops em_canid_ops = {
238 .kind = TCF_EM_CANID,
239 .change = em_canid_change,
240 .match = em_canid_match,
241 .destroy = em_canid_destroy,
242 .dump = em_canid_dump,
243 .owner = THIS_MODULE,
244 .link = LIST_HEAD_INIT(em_canid_ops.link)
247 static int __init init_em_canid(void)
249 return tcf_em_register(&em_canid_ops);
252 static void __exit exit_em_canid(void)
254 tcf_em_unregister(&em_canid_ops);
257 MODULE_LICENSE("GPL");
259 module_init(init_em_canid);
260 module_exit(exit_em_canid);
262 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID);