net/sched/em_nbyte.c

   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
  21 struct nbyte_data {
  22         struct tcf_em_nbyte     hdr;
  23         char                    pattern[0];
  24 };
  25
  26 static int em_nbyte_change(struct net *net, 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
  43 static 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->pattern, nbyte->hdr.len);
  55 }
  56
  57 static 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
  65 static int __init init_em_nbyte(void)
  66 {
  67         return tcf_em_register(&em_nbyte_ops);
  68 }
  69
  70 static void __exit exit_em_nbyte(void)
  71 {
  72         tcf_em_unregister(&em_nbyte_ops);
  73 }
  74
  75 MODULE_LICENSE("GPL");
  76
  77 module_init(init_em_nbyte);
  78 module_exit(exit_em_nbyte);
  79
  80 MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);