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 <linux/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); 26 u32 val = 0; 27 28 if (!ptr) 29 return 0; 30 ptr += cmp->off; 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 = get_unaligned_be16(ptr); 41 42 if (cmp_needs_transformation(cmp)) 43 val = be16_to_cpu(val); 44 break; 45 46 case TCF_EM_ALIGN_U32: 47 /* Worth checking boundaries? The branching seems 48 * to get worse. Visit again. 49 */ 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_DESCRIPTION("ematch classifier for basic data types(8/16/32 bit) against skb data"); 94 MODULE_LICENSE("GPL"); 95 96 module_init(init_em_cmp); 97 module_exit(exit_em_cmp); 98 99 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP); 100