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Rostislav Lisovyf057bbb2012-07-04 05:32:03 +02001/*
2 * em_canid.c Ematch rule to match CAN frames according to their CAN IDs
3 *
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.
8 *
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
16 */
17
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>
26
27#define EM_CAN_RULES_MAX 500
28
29struct canid_match {
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));
32
33 int rules_count;
34 int sff_rules_count;
35 int eff_rules_count;
36
37 /*
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
41 */
42 struct can_filter rules_raw[];
43};
44
45/**
46 * em_canid_get_id() - Extracts Can ID out of the sk_buff structure.
47 */
48static canid_t em_canid_get_id(struct sk_buff *skb)
49{
50 /* CAN ID is stored within the data field */
51 struct can_frame *cf = (struct can_frame *)skb->data;
52
53 return cf->can_id;
54}
55
56static void em_canid_sff_match_add(struct canid_match *cm, u32 can_id,
57 u32 can_mask)
58{
59 int i;
60
61 /*
62 * Limit can_mask and can_id to SFF range to
63 * protect against write after end of array
64 */
65 can_mask &= CAN_SFF_MASK;
66 can_id &= can_mask;
67
68 /* Single frame */
69 if (can_mask == CAN_SFF_MASK) {
70 set_bit(can_id, cm->match_sff);
71 return;
72 }
73
74 /* All frames */
75 if (can_mask == 0) {
76 bitmap_fill(cm->match_sff, (1 << CAN_SFF_ID_BITS));
77 return;
78 }
79
80 /*
81 * Individual frame filter.
82 * Add record (set bit to 1) for each ID that
83 * conforms particular rule
84 */
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);
88 }
89}
90
91static inline struct canid_match *em_canid_priv(struct tcf_ematch *m)
92{
93 return (struct canid_match *)m->data;
94}
95
96static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m,
97 struct tcf_pkt_info *info)
98{
99 struct canid_match *cm = em_canid_priv(m);
100 canid_t can_id;
101 int match = 0;
102 int i;
103 const struct can_filter *lp;
104
105 can_id = em_canid_get_id(skb);
106
107 if (can_id & CAN_EFF_FLAG) {
108 for (i = 0, lp = cm->rules_raw;
109 i < cm->eff_rules_count; i++, lp++) {
110 if (!(((lp->can_id ^ can_id) & lp->can_mask))) {
111 match = 1;
112 break;
113 }
114 }
115 } else { /* SFF */
116 can_id &= CAN_SFF_MASK;
117 match = (test_bit(can_id, cm->match_sff) ? 1 : 0);
118 }
119
120 return match;
121}
122
John Fastabend82a470f2014-10-05 21:27:53 -0700123static int em_canid_change(struct net *net, void *data, int len,
Rostislav Lisovyf057bbb2012-07-04 05:32:03 +0200124 struct tcf_ematch *m)
125{
126 struct can_filter *conf = data; /* Array with rules */
127 struct canid_match *cm;
Rostislav Lisovyf057bbb2012-07-04 05:32:03 +0200128 int i;
129
130 if (!len)
131 return -EINVAL;
132
133 if (len % sizeof(struct can_filter))
134 return -EINVAL;
135
136 if (len > sizeof(struct can_filter) * EM_CAN_RULES_MAX)
137 return -EINVAL;
138
139 cm = kzalloc(sizeof(struct canid_match) + len, GFP_KERNEL);
140 if (!cm)
141 return -ENOMEM;
142
143 cm->rules_count = len / sizeof(struct can_filter);
144
145 /*
146 * We need two for() loops for copying rules into two contiguous
147 * areas in rules_raw to process all eff rules with a simple loop.
148 * NB: The configuration interface supports sff and eff rules.
149 * We do not support filters here that match for the same can_id
150 * provided in a SFF and EFF frame (e.g. 0x123 / 0x80000123).
151 * For this (unusual case) two filters have to be specified. The
152 * SFF/EFF separation is done with the CAN_EFF_FLAG in the can_id.
153 */
154
155 /* Fill rules_raw with EFF rules first */
156 for (i = 0; i < cm->rules_count; i++) {
157 if (conf[i].can_id & CAN_EFF_FLAG) {
158 memcpy(cm->rules_raw + cm->eff_rules_count,
159 &conf[i],
160 sizeof(struct can_filter));
161
162 cm->eff_rules_count++;
163 }
164 }
165
166 /* append SFF frame rules */
167 for (i = 0; i < cm->rules_count; i++) {
168 if (!(conf[i].can_id & CAN_EFF_FLAG)) {
169 memcpy(cm->rules_raw
170 + cm->eff_rules_count
171 + cm->sff_rules_count,
172 &conf[i], sizeof(struct can_filter));
173
174 cm->sff_rules_count++;
175
176 em_canid_sff_match_add(cm,
177 conf[i].can_id, conf[i].can_mask);
178 }
179 }
180
181 m->datalen = sizeof(struct canid_match) + len;
182 m->data = (unsigned long)cm;
Rostislav Lisovyf057bbb2012-07-04 05:32:03 +0200183 return 0;
184}
185
John Fastabend82a470f2014-10-05 21:27:53 -0700186static void em_canid_destroy(struct tcf_ematch *m)
Rostislav Lisovyf057bbb2012-07-04 05:32:03 +0200187{
188 struct canid_match *cm = em_canid_priv(m);
189
190 kfree(cm);
191}
192
193static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m)
194{
195 struct canid_match *cm = em_canid_priv(m);
196
197 /*
198 * When configuring this ematch 'rules_count' is set not to exceed
199 * 'rules_raw' array size
200 */
201 if (nla_put_nohdr(skb, sizeof(struct can_filter) * cm->rules_count,
202 &cm->rules_raw) < 0)
203 return -EMSGSIZE;
204
205 return 0;
206}
207
208static struct tcf_ematch_ops em_canid_ops = {
209 .kind = TCF_EM_CANID,
210 .change = em_canid_change,
211 .match = em_canid_match,
212 .destroy = em_canid_destroy,
213 .dump = em_canid_dump,
214 .owner = THIS_MODULE,
215 .link = LIST_HEAD_INIT(em_canid_ops.link)
216};
217
218static int __init init_em_canid(void)
219{
220 return tcf_em_register(&em_canid_ops);
221}
222
223static void __exit exit_em_canid(void)
224{
225 tcf_em_unregister(&em_canid_ops);
226}
227
228MODULE_LICENSE("GPL");
229
230module_init(init_em_canid);
231module_exit(exit_em_canid);
232
233MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID);