net/sched/em_nbyte.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/em_nbyte.c N-Byte ematch
   4  *
   5  * Authors:     Thomas Graf <tgraf@suug.ch>
   6  */
   7
   8 #include <linux/gfp.h>
   9 #include <linux/module.h>
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/tc_ematch/tc_em_nbyte.h>
  15 #include <net/pkt_cls.h>
  16
  17 struct nbyte_data {
  18         struct tcf_em_nbyte     hdr;
  19         char                    pattern[];
  20 };
  21
  22 static int em_nbyte_change(struct net *net, void *data, int data_len,
  23                            struct tcf_ematch *em)
  24 {
  25         struct tcf_em_nbyte *nbyte = data;
  26
  27         if (data_len < sizeof(*nbyte) ||
  28             data_len < (sizeof(*nbyte) + nbyte->len))
  29                 return -EINVAL;
  30
  31         em->datalen = sizeof(*nbyte) + nbyte->len;
  32         em->data = (unsigned long)kmemdup(data, em->datalen, GFP_KERNEL);
  33         if (em->data == 0UL)
  34                 return -ENOBUFS;
  35
  36         return 0;
  37 }
  38
  39 static int em_nbyte_match(struct sk_buff *skb, struct tcf_ematch *em,
  40                           struct tcf_pkt_info *info)
  41 {
  42         struct nbyte_data *nbyte = (struct nbyte_data *) em->data;
  43         unsigned char *ptr = tcf_get_base_ptr(skb, nbyte->hdr.layer);
  44
  45         ptr += nbyte->hdr.off;
  46
  47         if (!tcf_valid_offset(skb, ptr, nbyte->hdr.len))
  48                 return 0;
  49
  50         return !memcmp(ptr, nbyte->pattern, nbyte->hdr.len);
  51 }
  52
  53 static struct tcf_ematch_ops em_nbyte_ops = {
  54         .kind     = TCF_EM_NBYTE,
  55         .change   = em_nbyte_change,
  56         .match    = em_nbyte_match,
  57         .owner    = THIS_MODULE,
  58         .link     = LIST_HEAD_INIT(em_nbyte_ops.link)
  59 };
  60
  61 static int __init init_em_nbyte(void)
  62 {
  63         return tcf_em_register(&em_nbyte_ops);
  64 }
  65
  66 static void __exit exit_em_nbyte(void)
  67 {
  68         tcf_em_unregister(&em_nbyte_ops);
  69 }
  70
  71 MODULE_LICENSE("GPL");
  72
  73 module_init(init_em_nbyte);
  74 module_exit(exit_em_nbyte);
  75
  76 MODULE_ALIAS_TCF_EMATCH(TCF_EM_NBYTE);