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); 81