1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/em_nbyte.c	N-Byte ematch
4 *
5 * Authors:	Thomas Graf <tgraf@suug.ch>
6 */
7
8#include <linux/gfp.h>
9#include <linux/module.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/string.h>
13#include <linux/skbuff.h>
14#include <linux/tc_ematch/tc_em_nbyte.h>
15#include <net/pkt_cls.h>
16
17struct nbyte_data {
18	struct tcf_em_nbyte	hdr;
19	char			pattern[];
20};
21
22static int em_nbyte_change(struct net *net, void *data, int data_len,
23			   struct tcf_ematch *em)
24{
25	struct tcf_em_nbyte *nbyte = data;
26
27	if (data_len < sizeof(*nbyte) ||
28	    data_len < (sizeof(*nbyte) + nbyte->len))
29		return -EINVAL;
30
31	em->datalen = sizeof(*nbyte) + nbyte->len;
32	em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
33	if (em->data == 0UL)
34		return -ENOMEM;
35
36	return 0;
37}
38
39static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
40			  struct tcf_pkt_info *info)
41{
42	struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
43	unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
44
45	ptr += nbyte->hdr.off;
46
47	if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
48		return 0;
49
50	return !memcmp(ptr, nbyte->pattern, nbyte->hdr.len);
51}
52
53static struct tcf_ematch_ops em_nbyte_ops = {
54	.kind	  = TCF_EM_NBYTE,
55	.change	  = em_nbyte_change,
56	.match	  = em_nbyte_match,
57	.owner	  = THIS_MODULE,
58	.link	  = LIST_HEAD_INIT(em_nbyte_ops.link)
59};
60
61static int __init init_em_nbyte(void)
62{
63	return tcf_em_register(&em_nbyte_ops);
64}
65
66static void __exit exit_em_nbyte(void)
67{
68	tcf_em_unregister(&em_nbyte_ops);
69}
70
71MODULE_DESCRIPTION("ematch classifier for arbitrary skb multi-bytes");
72MODULE_LICENSE("GPL");
73
74module_init(init_em_nbyte);
75module_exit(exit_em_nbyte);
76
77MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);
78