linux/net/sched/em_nbyte.c
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   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/gfp.h>
  13#include <linux/module.h>
  14#include <linux/types.h>
  15#include <linux/kernel.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        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
  80MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);
  81
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