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