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 <asm/unaligned.h>
18 #include <net/pkt_cls.h>
19
20 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
21 {
22 return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
23 }
24
25 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
26 struct tcf_pkt_info *info)
27 {
28 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
29 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
30 u32 val = 0;
31
32 if (!tcf_valid_offset(skb, ptr, cmp->align))
33 return 0;
34
35 switch (cmp->align) {
36 case TCF_EM_ALIGN_U8:
37 val = *ptr;
38 break;
39
40 case TCF_EM_ALIGN_U16:
41 val = get_unaligned_be16(ptr);
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 = get_unaligned_be32(ptr);
51
52 if (cmp_needs_transformation(cmp))
53 val = be32_to_cpu(val);
54 break;
55
56 default:
57 return 0;
58 }
59
60 if (cmp->mask)
61 val &= cmp->mask;
62
63 switch (cmp->opnd) {
64 case TCF_EM_OPND_EQ:
65 return val == cmp->val;
66 case TCF_EM_OPND_LT:
67 return val < cmp->val;
68 case TCF_EM_OPND_GT:
69 return val > cmp->val;
70 }
71
72 return 0;
73 }
74
75 static struct tcf_ematch_ops em_cmp_ops = {
76 .kind = TCF_EM_CMP,
77 .datalen = sizeof(struct tcf_em_cmp),
78 .match = em_cmp_match,
79 .owner = THIS_MODULE,
80 .link = LIST_HEAD_INIT(em_cmp_ops.link)
81 };
82
83 static int __init init_em_cmp(void)
84 {
85 return tcf_em_register(&em_cmp_ops);
86 }
87
88 static void __exit exit_em_cmp(void)
89 {
90 tcf_em_unregister(&em_cmp_ops);
91 }
92
93 MODULE_LICENSE("GPL");
94
95 module_init(init_em_cmp);
96 module_exit(exit_em_cmp);
97
98 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);
99
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