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ef65e431 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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2 | /* |
3 | * em_canid.c Ematch rule to match CAN frames according to their CAN IDs | |
4 | * | |
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5 | * Idea: Oliver Hartkopp <oliver.hartkopp@volkswagen.de> |
6 | * Copyright: (c) 2011 Czech Technical University in Prague | |
7 | * (c) 2011 Volkswagen Group Research | |
8 | * Authors: Michal Sojka <sojkam1@fel.cvut.cz> | |
9 | * Pavel Pisa <pisa@cmp.felk.cvut.cz> | |
10 | * Rostislav Lisovy <lisovy@gmail.cz> | |
11 | * Funded by: Volkswagen Group Research | |
12 | */ | |
13 | ||
14 | #include <linux/slab.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/types.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/skbuff.h> | |
20 | #include <net/pkt_cls.h> | |
21 | #include <linux/can.h> | |
22 | ||
23 | #define EM_CAN_RULES_MAX 500 | |
24 | ||
25 | struct canid_match { | |
26 | /* For each SFF CAN ID (11 bit) there is one record in this bitfield */ | |
27 | DECLARE_BITMAP(match_sff, (1 << CAN_SFF_ID_BITS)); | |
28 | ||
29 | int rules_count; | |
30 | int sff_rules_count; | |
31 | int eff_rules_count; | |
32 | ||
33 | /* | |
34 | * Raw rules copied from netlink message; Used for sending | |
35 | * information to userspace (when 'tc filter show' is invoked) | |
36 | * AND when matching EFF frames | |
37 | */ | |
38 | struct can_filter rules_raw[]; | |
39 | }; | |
40 | ||
41 | /** | |
42 | * em_canid_get_id() - Extracts Can ID out of the sk_buff structure. | |
43 | */ | |
44 | static canid_t em_canid_get_id(struct sk_buff *skb) | |
45 | { | |
46 | /* CAN ID is stored within the data field */ | |
47 | struct can_frame *cf = (struct can_frame *)skb->data; | |
48 | ||
49 | return cf->can_id; | |
50 | } | |
51 | ||
52 | static void em_canid_sff_match_add(struct canid_match *cm, u32 can_id, | |
53 | u32 can_mask) | |
54 | { | |
55 | int i; | |
56 | ||
57 | /* | |
58 | * Limit can_mask and can_id to SFF range to | |
59 | * protect against write after end of array | |
60 | */ | |
61 | can_mask &= CAN_SFF_MASK; | |
62 | can_id &= can_mask; | |
63 | ||
64 | /* Single frame */ | |
65 | if (can_mask == CAN_SFF_MASK) { | |
66 | set_bit(can_id, cm->match_sff); | |
67 | return; | |
68 | } | |
69 | ||
70 | /* All frames */ | |
71 | if (can_mask == 0) { | |
72 | bitmap_fill(cm->match_sff, (1 << CAN_SFF_ID_BITS)); | |
73 | return; | |
74 | } | |
75 | ||
76 | /* | |
77 | * Individual frame filter. | |
78 | * Add record (set bit to 1) for each ID that | |
79 | * conforms particular rule | |
80 | */ | |
81 | for (i = 0; i < (1 << CAN_SFF_ID_BITS); i++) { | |
82 | if ((i & can_mask) == can_id) | |
83 | set_bit(i, cm->match_sff); | |
84 | } | |
85 | } | |
86 | ||
87 | static inline struct canid_match *em_canid_priv(struct tcf_ematch *m) | |
88 | { | |
89 | return (struct canid_match *)m->data; | |
90 | } | |
91 | ||
92 | static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m, | |
93 | struct tcf_pkt_info *info) | |
94 | { | |
95 | struct canid_match *cm = em_canid_priv(m); | |
96 | canid_t can_id; | |
97 | int match = 0; | |
98 | int i; | |
99 | const struct can_filter *lp; | |
100 | ||
101 | can_id = em_canid_get_id(skb); | |
102 | ||
103 | if (can_id & CAN_EFF_FLAG) { | |
104 | for (i = 0, lp = cm->rules_raw; | |
105 | i < cm->eff_rules_count; i++, lp++) { | |
106 | if (!(((lp->can_id ^ can_id) & lp->can_mask))) { | |
107 | match = 1; | |
108 | break; | |
109 | } | |
110 | } | |
111 | } else { /* SFF */ | |
112 | can_id &= CAN_SFF_MASK; | |
113 | match = (test_bit(can_id, cm->match_sff) ? 1 : 0); | |
114 | } | |
115 | ||
116 | return match; | |
117 | } | |
118 | ||
82a470f1 | 119 | static int em_canid_change(struct net *net, void *data, int len, |
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120 | struct tcf_ematch *m) |
121 | { | |
122 | struct can_filter *conf = data; /* Array with rules */ | |
123 | struct canid_match *cm; | |
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124 | int i; |
125 | ||
126 | if (!len) | |
127 | return -EINVAL; | |
128 | ||
129 | if (len % sizeof(struct can_filter)) | |
130 | return -EINVAL; | |
131 | ||
132 | if (len > sizeof(struct can_filter) * EM_CAN_RULES_MAX) | |
133 | return -EINVAL; | |
134 | ||
135 | cm = kzalloc(sizeof(struct canid_match) + len, GFP_KERNEL); | |
136 | if (!cm) | |
137 | return -ENOMEM; | |
138 | ||
139 | cm->rules_count = len / sizeof(struct can_filter); | |
140 | ||
141 | /* | |
142 | * We need two for() loops for copying rules into two contiguous | |
143 | * areas in rules_raw to process all eff rules with a simple loop. | |
144 | * NB: The configuration interface supports sff and eff rules. | |
145 | * We do not support filters here that match for the same can_id | |
146 | * provided in a SFF and EFF frame (e.g. 0x123 / 0x80000123). | |
147 | * For this (unusual case) two filters have to be specified. The | |
148 | * SFF/EFF separation is done with the CAN_EFF_FLAG in the can_id. | |
149 | */ | |
150 | ||
151 | /* Fill rules_raw with EFF rules first */ | |
152 | for (i = 0; i < cm->rules_count; i++) { | |
153 | if (conf[i].can_id & CAN_EFF_FLAG) { | |
154 | memcpy(cm->rules_raw + cm->eff_rules_count, | |
155 | &conf[i], | |
156 | sizeof(struct can_filter)); | |
157 | ||
158 | cm->eff_rules_count++; | |
159 | } | |
160 | } | |
161 | ||
162 | /* append SFF frame rules */ | |
163 | for (i = 0; i < cm->rules_count; i++) { | |
164 | if (!(conf[i].can_id & CAN_EFF_FLAG)) { | |
165 | memcpy(cm->rules_raw | |
166 | + cm->eff_rules_count | |
167 | + cm->sff_rules_count, | |
168 | &conf[i], sizeof(struct can_filter)); | |
169 | ||
170 | cm->sff_rules_count++; | |
171 | ||
172 | em_canid_sff_match_add(cm, | |
173 | conf[i].can_id, conf[i].can_mask); | |
174 | } | |
175 | } | |
176 | ||
177 | m->datalen = sizeof(struct canid_match) + len; | |
178 | m->data = (unsigned long)cm; | |
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179 | return 0; |
180 | } | |
181 | ||
82a470f1 | 182 | static void em_canid_destroy(struct tcf_ematch *m) |
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183 | { |
184 | struct canid_match *cm = em_canid_priv(m); | |
185 | ||
186 | kfree(cm); | |
187 | } | |
188 | ||
189 | static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m) | |
190 | { | |
191 | struct canid_match *cm = em_canid_priv(m); | |
192 | ||
193 | /* | |
194 | * When configuring this ematch 'rules_count' is set not to exceed | |
195 | * 'rules_raw' array size | |
196 | */ | |
197 | if (nla_put_nohdr(skb, sizeof(struct can_filter) * cm->rules_count, | |
198 | &cm->rules_raw) < 0) | |
199 | return -EMSGSIZE; | |
200 | ||
201 | return 0; | |
202 | } | |
203 | ||
204 | static struct tcf_ematch_ops em_canid_ops = { | |
205 | .kind = TCF_EM_CANID, | |
206 | .change = em_canid_change, | |
207 | .match = em_canid_match, | |
208 | .destroy = em_canid_destroy, | |
209 | .dump = em_canid_dump, | |
210 | .owner = THIS_MODULE, | |
211 | .link = LIST_HEAD_INIT(em_canid_ops.link) | |
212 | }; | |
213 | ||
214 | static int __init init_em_canid(void) | |
215 | { | |
216 | return tcf_em_register(&em_canid_ops); | |
217 | } | |
218 | ||
219 | static void __exit exit_em_canid(void) | |
220 | { | |
221 | tcf_em_unregister(&em_canid_ops); | |
222 | } | |
223 | ||
224 | MODULE_LICENSE("GPL"); | |
225 | ||
226 | module_init(init_em_canid); | |
227 | module_exit(exit_em_canid); | |
228 | ||
229 | MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID); |