1/*
2 * net/sched/em_nbyte.c	N-Byte 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/string.h>
16#include <linux/skbuff.h>
17#include <linux/tc_ematch/tc_em_nbyte.h>
18#include <net/pkt_cls.h>
19
20struct nbyte_data
21{
22	struct tcf_em_nbyte	hdr;
23	char			pattern[0];
24};
25
26static int em_nbyte_change(struct tcf_proto *tp, void *data, int data_len,
27			   struct tcf_ematch *em)
28{
29	struct tcf_em_nbyte *nbyte = data;
30
31	if (data_len < sizeof(*nbyte) ||
32	    data_len < (sizeof(*nbyte) + nbyte->len))
33		return -EINVAL;
34
35	em->datalen = sizeof(*nbyte) + nbyte->len;
36	em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
37	if (em->data == 0UL)
38		return -ENOBUFS;
39
40	return 0;
41}
42
43static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
44			  struct tcf_pkt_info *info)
45{
46	struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
47	unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
48
49	ptr += nbyte->hdr.off;
50
51	if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
52		return 0;
53
54	return !memcmp(ptr + nbyte->hdr.off, nbyte->pattern, nbyte->hdr.len);
55}
56
57static struct tcf_ematch_ops em_nbyte_ops = {
58	.kind	  = TCF_EM_NBYTE,
59	.change	  = em_nbyte_change,
60	.match	  = em_nbyte_match,
61	.owner	  = THIS_MODULE,
62	.link	  = LIST_HEAD_INIT(em_nbyte_ops.link)
63};
64
65static int __init init_em_nbyte(void)
66{
67	return tcf_em_register(&em_nbyte_ops);
68}
69
70static void __exit exit_em_nbyte(void)
71{
72	tcf_em_unregister(&em_nbyte_ops);
73}
74
75MODULE_LICENSE("GPL");
76
77module_init(init_em_nbyte);
78module_exit(exit_em_nbyte);
79