em_nbyte.c revision 6ab3d5624e172c553004ecc862bfeac16d9d68b7 
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) kmalloc(em->datalen, GFP_KERNEL);
38	if (em->data == 0UL)
39		return -ENOBUFS;
40
41	memcpy((void *) em->data, data, em->datalen);
42
43	return 0;
44}
45
46static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
47			  struct tcf_pkt_info *info)
48{
49	struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
50	unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
51
52	ptr += nbyte->hdr.off;
53
54	if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
55		return 0;
56
57	return !memcmp(ptr + nbyte->hdr.off, nbyte->pattern, nbyte->hdr.len);
58}
59
60static struct tcf_ematch_ops em_nbyte_ops = {
61	.kind	  = TCF_EM_NBYTE,
62	.change	  = em_nbyte_change,
63	.match	  = em_nbyte_match,
64	.owner	  = THIS_MODULE,
65	.link	  = LIST_HEAD_INIT(em_nbyte_ops.link)
66};
67
68static int __init init_em_nbyte(void)
69{
70	return tcf_em_register(&em_nbyte_ops);
71}
72
73static void __exit exit_em_nbyte(void)
74{
75	tcf_em_unregister(&em_nbyte_ops);
76}
77
78MODULE_LICENSE("GPL");
79
80module_init(init_em_nbyte);
81module_exit(exit_em_nbyte);
82