net/sched/em_cmp.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * net/sched/em_cmp.c   Simple packet data comparison ematch
0004  *
0005  * Authors: Thomas Graf <tgraf@suug.ch>
0006  */
0007
0008 #include <linux/module.h>
0009 #include <linux/types.h>
0010 #include <linux/kernel.h>
0011 #include <linux/skbuff.h>
0012 #include <linux/tc_ematch/tc_em_cmp.h>
0013 #include <asm/unaligned.h>
0014 #include <net/pkt_cls.h>
0015
0016 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
0017 {
0018     return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
0019 }
0020
0021 static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em,
0022             struct tcf_pkt_info *info)
0023 {
0024     struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data;
0025     unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off;
0026     u32 val = 0;
0027
0028     if (!tcf_valid_offset(skb, ptr, cmp->align))
0029         return 0;
0030
0031     switch (cmp->align) {
0032     case TCF_EM_ALIGN_U8:
0033         val = *ptr;
0034         break;
0035
0036     case TCF_EM_ALIGN_U16:
0037         val = get_unaligned_be16(ptr);
0038
0039         if (cmp_needs_transformation(cmp))
0040             val = be16_to_cpu(val);
0041         break;
0042
0043     case TCF_EM_ALIGN_U32:
0044         /* Worth checking boundaries? The branching seems
0045          * to get worse. Visit again.
0046          */
0047         val = get_unaligned_be32(ptr);
0048
0049         if (cmp_needs_transformation(cmp))
0050             val = be32_to_cpu(val);
0051         break;
0052
0053     default:
0054         return 0;
0055     }
0056
0057     if (cmp->mask)
0058         val &= cmp->mask;
0059
0060     switch (cmp->opnd) {
0061     case TCF_EM_OPND_EQ:
0062         return val == cmp->val;
0063     case TCF_EM_OPND_LT:
0064         return val < cmp->val;
0065     case TCF_EM_OPND_GT:
0066         return val > cmp->val;
0067     }
0068
0069     return 0;
0070 }
0071
0072 static struct tcf_ematch_ops em_cmp_ops = {
0073     .kind     = TCF_EM_CMP,
0074     .datalen  = sizeof(struct tcf_em_cmp),
0075     .match    = em_cmp_match,
0076     .owner    = THIS_MODULE,
0077     .link     = LIST_HEAD_INIT(em_cmp_ops.link)
0078 };
0079
0080 static int __init init_em_cmp(void)
0081 {
0082     return tcf_em_register(&em_cmp_ops);
0083 }
0084
0085 static void __exit exit_em_cmp(void)
0086 {
0087     tcf_em_unregister(&em_cmp_ops);
0088 }
0089
0090 MODULE_LICENSE("GPL");
0091
0092 module_init(init_em_cmp);
0093 module_exit(exit_em_cmp);
0094
0095 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);