xref: /linux/net/sched/em_cmp.c (revision 4b132aacb0768ac1e652cf517097ea6f237214b9)
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_DESCRIPTION("ematch classifier for basic data types(8/16/32 bit) against skb data");
91 MODULE_LICENSE("GPL");
92 
93 module_init(init_em_cmp);
94 module_exit(exit_em_cmp);
95 
96 MODULE_ALIAS_TCF_EMATCH(TCF_EM_CMP);
97