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 <asm/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) + cmp->off;
26	u32 val = 0;
27
28	if (!tcf_valid_offset(skb, ptr, cmp->align))
29		return 0;
30
31	switch (cmp->align) {
32	case TCF_EM_ALIGN_U8:
33		val = *ptr;
34		break;
35
36	case TCF_EM_ALIGN_U16:
37		val = get_unaligned_be16(ptr);
38
39		if (cmp_needs_transformation(cmp))
40			val = be16_to_cpu(val);
41		break;
42
43	case TCF_EM_ALIGN_U32:
44		/* Worth checking boundaries? The branching seems
45		 * to get worse. Visit again.
46		 */
47		val = get_unaligned_be32(ptr);
48
49		if (cmp_needs_transformation(cmp))
50			val = be32_to_cpu(val);
51		break;
52
53	default:
54		return 0;
55	}
56
57	if (cmp->mask)
58		val &= cmp->mask;
59
60	switch (cmp->opnd) {
61	case TCF_EM_OPND_EQ:
62		return val == cmp->val;
63	case TCF_EM_OPND_LT:
64		return val < cmp->val;
65	case TCF_EM_OPND_GT:
66		return val > cmp->val;
67	}
68
69	return 0;
70}
71
72static struct tcf_ematch_ops em_cmp_ops = {
73	.kind	  = TCF_EM_CMP,
74	.datalen  = sizeof(struct tcf_em_cmp),
75	.match	  = em_cmp_match,
76	.owner	  = THIS_MODULE,
77	.link	  = LIST_HEAD_INIT(em_cmp_ops.link)
78};
79
80static int __init init_em_cmp(void)
81{
82	return tcf_em_register(&em_cmp_ops);
83}
84
85static void __exit exit_em_cmp(void)
86{
87	tcf_em_unregister(&em_cmp_ops);
88}
89
90MODULE_DESCRIPTION("ematch classifier for basic data types(8/16/32 bit) against skb data");
91MODULE_LICENSE("GPL");
92
93module_init(init_em_cmp);
94module_exit(exit_em_cmp);
95
96MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);
97