em_cmp.c

 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);