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 <asm/unaligned.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 = get_unaligned_be16(ptr); 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 = get_unaligned_be32(ptr); 51 52 if (cmp_needs_transformation(cmp)) 53 val = be32_to_cpu(val); 54 break; 55 56 default: 57 return 0; 58 } 59 60 if (cmp->mask) 61 val &= cmp->mask; 62 63 switch (cmp->opnd) { 64 case TCF_EM_OPND_EQ: 65 return val == cmp->val; 66 case TCF_EM_OPND_LT: 67 return val < cmp->val; 68 case TCF_EM_OPND_GT: 69 return val > cmp->val; 70 } 71 72 return 0; 73 } 74 75 static struct tcf_ematch_ops em_cmp_ops = { 76 .kind = TCF_EM_CMP, 77 .datalen = sizeof(struct tcf_em_cmp), 78 .match = em_cmp_match, 79 .owner = THIS_MODULE, 80 .link = LIST_HEAD_INIT(em_cmp_ops.link) 81 }; 82 83 static int __init init_em_cmp(void) 84 { 85 return tcf_em_register(&em_cmp_ops); 86 } 87 88 static void __exit exit_em_cmp(void) 89 { 90 tcf_em_unregister(&em_cmp_ops); 91 } 92 93 MODULE_LICENSE("GPL"); 94 95 module_init(init_em_cmp); 96 module_exit(exit_em_cmp); 97 98 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP); 99