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/module.h> 13 #include <linux/types.h> 14 #include <linux/kernel.h> 15 #include <linux/skbuff.h> 16 #include <linux/tc_ematch/tc_em_cmp.h> 17 #include <net/pkt_cls.h> 18 19 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp) 20 { 21 return unlikely(cmp->flags & TCF_EM_CMP_TRANS); 22 } 23 24 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em, 25 struct tcf_pkt_info *info) 26 { 27 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data; 28 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off; 29 u32 val = 0; 30 31 if (!tcf_valid_offset(skb, ptr, cmp->align)) 32 return 0; 33 34 switch (cmp->align) { 35 case TCF_EM_ALIGN_U8: 36 val = *ptr; 37 break; 38 39 case TCF_EM_ALIGN_U16: 40 val = *ptr << 8; 41 val |= *(ptr+1); 42 43 if (cmp_needs_transformation(cmp)) 44 val = be16_to_cpu(val); 45 break; 46 47 case TCF_EM_ALIGN_U32: 48 /* Worth checking boundries? The branching seems 49 * to get worse. Visit again. */ 50 val = *ptr << 24; 51 val |= *(ptr+1) << 16; 52 val |= *(ptr+2) << 8; 53 val |= *(ptr+3); 54 55 if (cmp_needs_transformation(cmp)) 56 val = be32_to_cpu(val); 57 break; 58 59 default: 60 return 0; 61 } 62 63 if (cmp->mask) 64 val &= cmp->mask; 65 66 switch (cmp->opnd) { 67 case TCF_EM_OPND_EQ: 68 return val == cmp->val; 69 case TCF_EM_OPND_LT: 70 return val < cmp->val; 71 case TCF_EM_OPND_GT: 72 return val > cmp->val; 73 } 74 75 return 0; 76 } 77 78 static struct tcf_ematch_ops em_cmp_ops = { 79 .kind = TCF_EM_CMP, 80 .datalen = sizeof(struct tcf_em_cmp), 81 .match = em_cmp_match, 82 .owner = THIS_MODULE, 83 .link = LIST_HEAD_INIT(em_cmp_ops.link) 84 }; 85 86 static int __init init_em_cmp(void) 87 { 88 return tcf_em_register(&em_cmp_ops); 89 } 90 91 static void __exit exit_em_cmp(void) 92 { 93 tcf_em_unregister(&em_cmp_ops); 94 } 95 96 MODULE_LICENSE("GPL"); 97 98 module_init(init_em_cmp); 99 module_exit(exit_em_cmp); 100 101