1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/sched/em_cmp.c Simple packet data comparison ematch 4 * 5 * Authors: Thomas Graf <tgraf@suug.ch> 6 */ 7 8 #include <linux/module.h> 9 #include <linux/types.h> 10 #include <linux/kernel.h> 11 #include <linux/skbuff.h> 12 #include <linux/tc_ematch/tc_em_cmp.h> 13 #include <asm/unaligned.h> 14 #include <net/pkt_cls.h> 15 16 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp) 17 { 18 return unlikely(cmp->flags & TCF_EM_CMP_TRANS); 19 } 20 21 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em, 22 struct tcf_pkt_info *info) 23 { 24 struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data; 25 unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off; 26 u32 val = 0; 27 28 if (!tcf_valid_offset(skb, ptr, cmp->align)) 29 return 0; 30 31 switch (cmp->align) { 32 case TCF_EM_ALIGN_U8: 33 val = *ptr; 34 break; 35 36 case TCF_EM_ALIGN_U16: 37 val = get_unaligned_be16(ptr); 38 39 if (cmp_needs_transformation(cmp)) 40 val = be16_to_cpu(val); 41 break; 42 43 case TCF_EM_ALIGN_U32: 44 /* Worth checking boundaries? The branching seems 45 * to get worse. Visit again. 46 */ 47 val = get_unaligned_be32(ptr); 48 49 if (cmp_needs_transformation(cmp)) 50 val = be32_to_cpu(val); 51 break; 52 53 default: 54 return 0; 55 } 56 57 if (cmp->mask) 58 val &= cmp->mask; 59 60 switch (cmp->opnd) { 61 case TCF_EM_OPND_EQ: 62 return val == cmp->val; 63 case TCF_EM_OPND_LT: 64 return val < cmp->val; 65 case TCF_EM_OPND_GT: 66 return val > cmp->val; 67 } 68 69 return 0; 70 } 71 72 static struct tcf_ematch_ops em_cmp_ops = { 73 .kind = TCF_EM_CMP, 74 .datalen = sizeof(struct tcf_em_cmp), 75 .match = em_cmp_match, 76 .owner = THIS_MODULE, 77 .link = LIST_HEAD_INIT(em_cmp_ops.link) 78 }; 79 80 static int __init init_em_cmp(void) 81 { 82 return tcf_em_register(&em_cmp_ops); 83 } 84 85 static void __exit exit_em_cmp(void) 86 { 87 tcf_em_unregister(&em_cmp_ops); 88 } 89 90 MODULE_LICENSE("GPL"); 91 92 module_init(init_em_cmp); 93 module_exit(exit_em_cmp); 94 95 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP); 96