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