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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/em_cmp.c Simple packet data comparison ematch
4 *
5 * Authors: Thomas Graf <tgraf@suug.ch>
6 */
7
8#include <linux/module.h>
9#include <linux/types.h>
10#include <linux/kernel.h>
11#include <linux/skbuff.h>
12#include <linux/tc_ematch/tc_em_cmp.h>
13#include <linux/unaligned.h>
14#include <net/pkt_cls.h>
15
16static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
17{
18 return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
19}
20
21static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
22 struct tcf_pkt_info *info)
23{
24 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
25 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer);
26 u32 val = 0;
27
28 if (!ptr)
29 return 0;
30 ptr += cmp->off;
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 = get_unaligned_be16(ptr);
41
42 if (cmp_needs_transformation(cmp))
43 val = be16_to_cpu(val);
44 break;
45
46 case TCF_EM_ALIGN_U32:
47 /* Worth checking boundaries? The branching seems
48 * to get worse. Visit again.
49 */
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
75static 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
83static int __init init_em_cmp(void)
84{
85 return tcf_em_register(&em_cmp_ops);
86}
87
88static void __exit exit_em_cmp(void)
89{
90 tcf_em_unregister(&em_cmp_ops);
91}
92
93MODULE_DESCRIPTION("ematch classifier for basic data types(8/16/32 bit) against skb data");
94MODULE_LICENSE("GPL");
95
96module_init(init_em_cmp);
97module_exit(exit_em_cmp);
98
99MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);