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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. | |
90ac5d03 | 43 | * @skb: buffer to extract Can ID from |
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44 | */ |
45 | static canid_t em_canid_get_id(struct sk_buff *skb) | |
46 | { | |
47 | /* CAN ID is stored within the data field */ | |
48 | struct can_frame *cf = (struct can_frame *)skb->data; | |
49 | ||
50 | return cf->can_id; | |
51 | } | |
52 | ||
53 | static void em_canid_sff_match_add(struct canid_match *cm, u32 can_id, | |
54 | u32 can_mask) | |
55 | { | |
56 | int i; | |
57 | ||
58 | /* | |
59 | * Limit can_mask and can_id to SFF range to | |
60 | * protect against write after end of array | |
61 | */ | |
62 | can_mask &= CAN_SFF_MASK; | |
63 | can_id &= can_mask; | |
64 | ||
65 | /* Single frame */ | |
66 | if (can_mask == CAN_SFF_MASK) { | |
67 | set_bit(can_id, cm->match_sff); | |
68 | return; | |
69 | } | |
70 | ||
71 | /* All frames */ | |
72 | if (can_mask == 0) { | |
73 | bitmap_fill(cm->match_sff, (1 << CAN_SFF_ID_BITS)); | |
74 | return; | |
75 | } | |
76 | ||
77 | /* | |
78 | * Individual frame filter. | |
79 | * Add record (set bit to 1) for each ID that | |
80 | * conforms particular rule | |
81 | */ | |
82 | for (i = 0; i < (1 << CAN_SFF_ID_BITS); i++) { | |
83 | if ((i & can_mask) == can_id) | |
84 | set_bit(i, cm->match_sff); | |
85 | } | |
86 | } | |
87 | ||
88 | static inline struct canid_match *em_canid_priv(struct tcf_ematch *m) | |
89 | { | |
90 | return (struct canid_match *)m->data; | |
91 | } | |
92 | ||
93 | static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m, | |
94 | struct tcf_pkt_info *info) | |
95 | { | |
96 | struct canid_match *cm = em_canid_priv(m); | |
97 | canid_t can_id; | |
98 | int match = 0; | |
99 | int i; | |
100 | const struct can_filter *lp; | |
101 | ||
102 | can_id = em_canid_get_id(skb); | |
103 | ||
104 | if (can_id & CAN_EFF_FLAG) { | |
105 | for (i = 0, lp = cm->rules_raw; | |
106 | i < cm->eff_rules_count; i++, lp++) { | |
107 | if (!(((lp->can_id ^ can_id) & lp->can_mask))) { | |
108 | match = 1; | |
109 | break; | |
110 | } | |
111 | } | |
112 | } else { /* SFF */ | |
113 | can_id &= CAN_SFF_MASK; | |
114 | match = (test_bit(can_id, cm->match_sff) ? 1 : 0); | |
115 | } | |
116 | ||
117 | return match; | |
118 | } | |
119 | ||
82a470f1 | 120 | static int em_canid_change(struct net *net, void *data, int len, |
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121 | struct tcf_ematch *m) |
122 | { | |
123 | struct can_filter *conf = data; /* Array with rules */ | |
124 | struct canid_match *cm; | |
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125 | int i; |
126 | ||
127 | if (!len) | |
128 | return -EINVAL; | |
129 | ||
130 | if (len % sizeof(struct can_filter)) | |
131 | return -EINVAL; | |
132 | ||
133 | if (len > sizeof(struct can_filter) * EM_CAN_RULES_MAX) | |
134 | return -EINVAL; | |
135 | ||
136 | cm = kzalloc(sizeof(struct canid_match) + len, GFP_KERNEL); | |
137 | if (!cm) | |
138 | return -ENOMEM; | |
139 | ||
140 | cm->rules_count = len / sizeof(struct can_filter); | |
141 | ||
142 | /* | |
143 | * We need two for() loops for copying rules into two contiguous | |
144 | * areas in rules_raw to process all eff rules with a simple loop. | |
145 | * NB: The configuration interface supports sff and eff rules. | |
146 | * We do not support filters here that match for the same can_id | |
147 | * provided in a SFF and EFF frame (e.g. 0x123 / 0x80000123). | |
148 | * For this (unusual case) two filters have to be specified. The | |
149 | * SFF/EFF separation is done with the CAN_EFF_FLAG in the can_id. | |
150 | */ | |
151 | ||
152 | /* Fill rules_raw with EFF rules first */ | |
153 | for (i = 0; i < cm->rules_count; i++) { | |
154 | if (conf[i].can_id & CAN_EFF_FLAG) { | |
155 | memcpy(cm->rules_raw + cm->eff_rules_count, | |
156 | &conf[i], | |
157 | sizeof(struct can_filter)); | |
158 | ||
159 | cm->eff_rules_count++; | |
160 | } | |
161 | } | |
162 | ||
163 | /* append SFF frame rules */ | |
164 | for (i = 0; i < cm->rules_count; i++) { | |
165 | if (!(conf[i].can_id & CAN_EFF_FLAG)) { | |
166 | memcpy(cm->rules_raw | |
167 | + cm->eff_rules_count | |
168 | + cm->sff_rules_count, | |
169 | &conf[i], sizeof(struct can_filter)); | |
170 | ||
171 | cm->sff_rules_count++; | |
172 | ||
173 | em_canid_sff_match_add(cm, | |
174 | conf[i].can_id, conf[i].can_mask); | |
175 | } | |
176 | } | |
177 | ||
178 | m->datalen = sizeof(struct canid_match) + len; | |
179 | m->data = (unsigned long)cm; | |
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180 | return 0; |
181 | } | |
182 | ||
82a470f1 | 183 | static void em_canid_destroy(struct tcf_ematch *m) |
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184 | { |
185 | struct canid_match *cm = em_canid_priv(m); | |
186 | ||
187 | kfree(cm); | |
188 | } | |
189 | ||
190 | static int em_canid_dump(struct sk_buff *skb, struct tcf_ematch *m) | |
191 | { | |
192 | struct canid_match *cm = em_canid_priv(m); | |
193 | ||
194 | /* | |
195 | * When configuring this ematch 'rules_count' is set not to exceed | |
196 | * 'rules_raw' array size | |
197 | */ | |
198 | if (nla_put_nohdr(skb, sizeof(struct can_filter) * cm->rules_count, | |
199 | &cm->rules_raw) < 0) | |
200 | return -EMSGSIZE; | |
201 | ||
202 | return 0; | |
203 | } | |
204 | ||
205 | static struct tcf_ematch_ops em_canid_ops = { | |
206 | .kind = TCF_EM_CANID, | |
207 | .change = em_canid_change, | |
208 | .match = em_canid_match, | |
209 | .destroy = em_canid_destroy, | |
210 | .dump = em_canid_dump, | |
211 | .owner = THIS_MODULE, | |
212 | .link = LIST_HEAD_INIT(em_canid_ops.link) | |
213 | }; | |
214 | ||
215 | static int __init init_em_canid(void) | |
216 | { | |
217 | return tcf_em_register(&em_canid_ops); | |
218 | } | |
219 | ||
220 | static void __exit exit_em_canid(void) | |
221 | { | |
222 | tcf_em_unregister(&em_canid_ops); | |
223 | } | |
224 | ||
225 | MODULE_LICENSE("GPL"); | |
226 | ||
227 | module_init(init_em_canid); | |
228 | module_exit(exit_em_canid); | |
229 | ||
230 | MODULE_ALIAS_TCF_EMATCH(TCF_EM_CANID); |