1 /*
2 * net/sched/em_cmp.c Simple packet data comparison ematch
3 *
4 * This program is free software; you can redistribute 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 * Authors: Thomas Graf <tgraf@suug.ch>
10 */
11
12 #include <linux/module.h>
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
16 #include <linux/tc_ematch/tc_em_cmp.h>
17 #include <net/pkt_cls.h>
18
19 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
20 {
21 return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
22 }
23
24 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
25 struct tcf_pkt_info *info)
26 {
27 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
28 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
29 u32 val = 0;
30
31 if (!tcf_valid_offset(skb, ptr, cmp->align))
32 return 0;
33
34 switch (cmp->align) {
35 case TCF_EM_ALIGN_U8:
36 val = *ptr;
37 break;
38
39 case TCF_EM_ALIGN_U16:
40 val = *ptr << 8;
41 val |= *(ptr+1);
42
43 if (cmp_needs_transformation(cmp))
44 val = be16_to_cpu(val);
45 break;
46
47 case TCF_EM_ALIGN_U32:
48 /* Worth checking boundries? The branching seems
49 * to get worse. Visit again. */
50 val = *ptr << 24;
51 val |= *(ptr+1) << 16;
52 val |= *(ptr+2) << 8;
53 val |= *(ptr+3);
54
55 if (cmp_needs_transformation(cmp))
56 val = be32_to_cpu(val);
57 break;
58
59 default:
60 return 0;
61 }
62
63 if (cmp->mask)
64 val &= cmp->mask;
65
66 switch (cmp->opnd) {
67 case TCF_EM_OPND_EQ:
68 return val == cmp->val;
69 case TCF_EM_OPND_LT:
70 return val < cmp->val;
71 case TCF_EM_OPND_GT:
72 return val > cmp->val;
73 }
74
75 return 0;
76 }
77
78 static struct tcf_ematch_ops em_cmp_ops = {
79 .kind = TCF_EM_CMP,
80 .datalen = sizeof(struct tcf_em_cmp),
81 .match = em_cmp_match,
82 .owner = THIS_MODULE,
83 .link = LIST_HEAD_INIT(em_cmp_ops.link)
84 };
85
86 static int __init init_em_cmp(void)
87 {
88 return tcf_em_register(&em_cmp_ops);
89 }
90
91 static void __exit exit_em_cmp(void)
92 {
93 tcf_em_unregister(&em_cmp_ops);
94 }
95
96 MODULE_LICENSE("GPL");
97
98 module_init(init_em_cmp);
99 module_exit(exit_em_cmp);
100
101 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);
102
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