1 /* 2 * net/sched/em_cmp.c Simple packet data comparison 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/skbuff.h> 17 #include <linux/tc_ematch/tc_em_cmp.h> 18 #include <net/pkt_cls.h> 19 20 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp) 21 { 22 return unlikely(cmp->flags & TCF_EM_CMP_TRANS); 23 } 24 25 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em, 26 struct tcf_pkt_info *info) 27 { 28 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data; 29 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off; 30 u32 val = 0; 31 32 if (!tcf_valid_offset(skb, ptr, cmp->align)) 33 return 0; 34 35 switch (cmp->align) { 36 case TCF_EM_ALIGN_U8: 37 val = *ptr; 38 break; 39 40 case TCF_EM_ALIGN_U16: 41 val = *ptr << 8; 42 val |= *(ptr+1); 43 44 if (cmp_needs_transformation(cmp)) 45 val = be16_to_cpu(val); 46 break; 47 48 case TCF_EM_ALIGN_U32: 49 /* Worth checking boundries? The branching seems 50 * to get worse. Visit again. */ 51 val = *ptr << 24; 52 val |= *(ptr+1) << 16; 53 val |= *(ptr+2) << 8; 54 val |= *(ptr+3); 55 56 if (cmp_needs_transformation(cmp)) 57 val = be32_to_cpu(val); 58 break; 59 60 default: 61 return 0; 62 } 63 64 if (cmp->mask) 65 val &= cmp->mask; 66 67 switch (cmp->opnd) { 68 case TCF_EM_OPND_EQ: 69 return val == cmp->val; 70 case TCF_EM_OPND_LT: 71 return val < cmp->val; 72 case TCF_EM_OPND_GT: 73 return val > cmp->val; 74 } 75 76 return 0; 77 } 78 79 static struct tcf_ematch_ops em_cmp_ops = { 80 .kind = TCF_EM_CMP, 81 .datalen = sizeof(struct tcf_em_cmp), 82 .match = em_cmp_match, 83 .owner = THIS_MODULE, 84 .link = LIST_HEAD_INIT(em_cmp_ops.link) 85 }; 86 87 static int __init init_em_cmp(void) 88 { 89 return tcf_em_register(&em_cmp_ops); 90 } 91 92 static void __exit exit_em_cmp(void) 93 { 94 tcf_em_unregister(&em_cmp_ops); 95 } 96 97 MODULE_LICENSE("GPL"); 98 99 module_init(init_em_cmp); 100 module_exit(exit_em_cmp); 101 102