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f057bbb6 RL |
1 | /* |
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 | ||
29 | struct 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 | */ | |
48 | static 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 | ||
56 | static 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 | ||
91 | static inline struct canid_match *em_canid_priv(struct tcf_ematch *m) | |
92 | { | |
93 | return (struct canid_match *)m->data; | |
94 | } | |
95 | ||
96 | static 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 | ||
123 | static int em_canid_change(struct tcf_proto *tp, void *data, int len, | |
124 | struct tcf_ematch *m) | |
125 | { | |
126 | struct can_filter *conf = data; /* Array with rules */ | |
127 | struct canid_match *cm; | |
128 | struct canid_match *cm_old = (struct canid_match *)m->data; | |
129 | int i; | |
130 | ||
131 | if (!len) | |
132 | return -EINVAL; | |
133 | ||
134 | if (len % sizeof(struct can_filter)) | |
135 | return -EINVAL; | |
136 | ||
137 | if (len > sizeof(struct can_filter) * EM_CAN_RULES_MAX) | |
138 | return -EINVAL; | |
139 | ||
140 | cm = kzalloc(sizeof(struct canid_match) + len, GFP_KERNEL); | |
141 | if (!cm) | |
142 | return -ENOMEM; | |
143 | ||
144 | cm->rules_count = len / sizeof(struct can_filter); | |
145 | ||
146 | /* | |
147 | * We need two for() loops for copying rules into two contiguous | |
148 | * areas in rules_raw to process all eff rules with a simple loop. | |
149 | * NB: The configuration interface supports sff and eff rules. | |
150 | * We do not support filters here that match for the same can_id | |
151 | * provided in a SFF and EFF frame (e.g. 0x123 / 0x80000123). | |
152 | * For this (unusual case) two filters have to be specified. The | |
153 | * SFF/EFF separation is done with the CAN_EFF_FLAG in the can_id. | |
154 | */ | |
155 | ||
156 | /* Fill rules_raw with EFF rules first */ | |
157 | for (i = 0; i < cm->rules_count; i++) { | |
158 | if (conf[i].can_id & CAN_EFF_FLAG) { | |
159 | memcpy(cm->rules_raw + cm->eff_rules_count, | |
160 | &conf[i], | |
161 | sizeof(struct can_filter)); | |
162 | ||
163 | cm->eff_rules_count++; | |
164 | } | |
165 | } | |
166 | ||
167 | /* append SFF frame rules */ | |
168 | for (i = 0; i < cm->rules_count; i++) { | |
169 | if (!(conf[i].can_id & CAN_EFF_FLAG)) { | |
170 | memcpy(cm->rules_raw | |
171 | + cm->eff_rules_count | |
172 | + cm->sff_rules_count, | |
173 | &conf[i], sizeof(struct can_filter)); | |
174 | ||
175 | cm->sff_rules_count++; | |
176 | ||
177 | em_canid_sff_match_add(cm, | |
178 | conf[i].can_id, conf[i].can_mask); | |
179 | } | |
180 | } | |
181 | ||
182 | m->datalen = sizeof(struct canid_match) + len; | |
183 | m->data = (unsigned long)cm; | |
184 | ||
185 | if (cm_old != NULL) { | |
186 | pr_err("canid: Configuring an existing ematch!\n"); | |
187 | kfree(cm_old); | |
188 | } | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | static void em_canid_destroy(struct tcf_proto *tp, struct tcf_ematch *m) | |
194 | { | |
195 | struct canid_match *cm = em_canid_priv(m); | |
196 | ||
197 | kfree(cm); | |
198 | } | |
199 | ||
200 | static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m) | |
201 | { | |
202 | struct canid_match *cm = em_canid_priv(m); | |
203 | ||
204 | /* | |
205 | * When configuring this ematch 'rules_count' is set not to exceed | |
206 | * 'rules_raw' array size | |
207 | */ | |
208 | if (nla_put_nohdr(skb, sizeof(struct can_filter) * cm->rules_count, | |
209 | &cm->rules_raw) < 0) | |
210 | return -EMSGSIZE; | |
211 | ||
212 | return 0; | |
213 | } | |
214 | ||
215 | static struct tcf_ematch_ops em_canid_ops = { | |
216 | .kind = TCF_EM_CANID, | |
217 | .change = em_canid_change, | |
218 | .match = em_canid_match, | |
219 | .destroy = em_canid_destroy, | |
220 | .dump = em_canid_dump, | |
221 | .owner = THIS_MODULE, | |
222 | .link = LIST_HEAD_INIT(em_canid_ops.link) | |
223 | }; | |
224 | ||
225 | static int __init init_em_canid(void) | |
226 | { | |
227 | return tcf_em_register(&em_canid_ops); | |
228 | } | |
229 | ||
230 | static void __exit exit_em_canid(void) | |
231 | { | |
232 | tcf_em_unregister(&em_canid_ops); | |
233 | } | |
234 | ||
235 | MODULE_LICENSE("GPL"); | |
236 | ||
237 | module_init(init_em_canid); | |
238 | module_exit(exit_em_canid); | |
239 | ||
240 | MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID); |