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
cmp_needs_transformation(struct tcf_em_cmp * cmp)16 static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp)
17 {
18 return unlikely(cmp->flags & TCF_EM_CMP_TRANS);
19 }
20
em_cmp_match(struct sk_buff * skb,struct tcf_ematch * em,struct tcf_pkt_info * info)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
init_em_cmp(void)80 static int __init init_em_cmp(void)
81 {
82 return tcf_em_register(&em_cmp_ops);
83 }
84
exit_em_cmp(void)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