LXR linux/net/sched/em

   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
  16static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
  17{
  18        return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
  19}
  20
  21static 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
  72static 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
  80static int __init init_em_cmp(void)
  81{
  82        return tcf_em_register(&em_cmp_ops);
  83}
  84
  85static void __exit exit_em_cmp(void)
  86{
  87        tcf_em_unregister(&em_cmp_ops);
  88}
  89
  90MODULE_LICENSE("GPL");
  91
  92module_init(init_em_cmp);
  93module_exit(exit_em_cmp);
  94
  95MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);
  96