em_nbyte.c revision 10297b99315e5e08fe623ba56da35db1fee69ba9 
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/sched.h>
16#include <linux/string.h>
17#include <linux/skbuff.h>
18#include <linux/tc_ematch/tc_em_nbyte.h>
19#include <net/pkt_cls.h>
20
21struct nbyte_data
22{
23	struct tcf_em_nbyte	hdr;
24	char			pattern[0];
25};
26
27static int em_nbyte_change(struct tcf_proto *tp, void *data, int data_len,
28			   struct tcf_ematch *em)
29{
30	struct tcf_em_nbyte *nbyte = data;
31
32	if (data_len < sizeof(*nbyte) ||
33	    data_len < (sizeof(*nbyte) + nbyte->len))
34		return -EINVAL;
35
36	em->datalen = sizeof(*nbyte) + nbyte->len;
37	em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
38	if (em->data == 0UL)
39		return -ENOBUFS;
40
41	return 0;
42}
43
44static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
45			  struct tcf_pkt_info *info)
46{
47	struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
48	unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
49
50	ptr += nbyte->hdr.off;
51
52	if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
53		return 0;
54
55	return !memcmp(ptr + nbyte->hdr.off, nbyte->pattern, nbyte->hdr.len);
56}
57
58static struct tcf_ematch_ops em_nbyte_ops = {
59	.kind	  = TCF_EM_NBYTE,
60	.change	  = em_nbyte_change,
61	.match	  = em_nbyte_match,
62	.owner	  = THIS_MODULE,
63	.link	  = LIST_HEAD_INIT(em_nbyte_ops.link)
64};
65
66static int __init init_em_nbyte(void)
67{
68	return tcf_em_register(&em_nbyte_ops);
69}
70
71static void __exit exit_em_nbyte(void)
72{
73	tcf_em_unregister(&em_nbyte_ops);
74}
75
76MODULE_LICENSE("GPL");
77
78module_init(init_em_nbyte);
79module_exit(exit_em_nbyte);
80