| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame] | 1 | /* |
| 2 | * net/sched/em_cmp.c Simple packet data comparison ematch |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public License |
| 6 | * as published by the Free Software Foundation; either version |
| 7 | * 2 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * Authors: Thomas Graf <tgraf@suug.ch> |
| 10 | */ |
| 11 | |
| 12 | #include <linux/module.h> |
| 13 | #include <linux/types.h> |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/skbuff.h> |
| 16 | #include <linux/tc_ematch/tc_em_cmp.h> |
| 17 | #include <asm/unaligned.h> |
| 18 | #include <net/pkt_cls.h> |
| 19 | |
| 20 | static inline int cmp_needs_transformation(struct tcf_em_cmp *cmp) |
| 21 | { |
| 22 | return unlikely(cmp->flags & TCF_EM_CMP_TRANS); |
| 23 | } |
| 24 | |
| 25 | static int em_cmp_match(struct sk_buff *skb, struct tcf_ematch *em, |
| 26 | struct tcf_pkt_info *info) |
| 27 | { |
| 28 | struct tcf_em_cmp *cmp = (struct tcf_em_cmp *) em->data; |
| 29 | unsigned char *ptr = tcf_get_base_ptr(skb, cmp->layer) + cmp->off; |
| 30 | u32 val = 0; |
| 31 | |
| 32 | if (!tcf_valid_offset(skb, ptr, cmp->align)) |
| 33 | return 0; |
| 34 | |
| 35 | switch (cmp->align) { |
| 36 | case TCF_EM_ALIGN_U8: |
| 37 | val = *ptr; |
| 38 | break; |
| 39 | |
| 40 | case TCF_EM_ALIGN_U16: |
| 41 | val = get_unaligned_be16(ptr); |
| 42 | |
| 43 | if (cmp_needs_transformation(cmp)) |
| 44 | val = be16_to_cpu(val); |
| 45 | break; |
| 46 | |
| 47 | case TCF_EM_ALIGN_U32: |
| 48 | /* Worth checking boundries? The branching seems |
| 49 | * to get worse. Visit again. |
| 50 | */ |
| 51 | val = get_unaligned_be32(ptr); |
| 52 | |
| 53 | if (cmp_needs_transformation(cmp)) |
| 54 | val = be32_to_cpu(val); |
| 55 | break; |
| 56 | |
| 57 | default: |
| 58 | return 0; |
| 59 | } |
| 60 | |
| 61 | if (cmp->mask) |
| 62 | val &= cmp->mask; |
| 63 | |
| 64 | switch (cmp->opnd) { |
| 65 | case TCF_EM_OPND_EQ: |
| 66 | return val == cmp->val; |
| 67 | case TCF_EM_OPND_LT: |
| 68 | return val < cmp->val; |
| 69 | case TCF_EM_OPND_GT: |
| 70 | return val > cmp->val; |
| 71 | } |
| 72 | |
| 73 | return 0; |
| 74 | } |
| 75 | |
| 76 | static struct tcf_ematch_ops em_cmp_ops = { |
| 77 | .kind = TCF_EM_CMP, |
| 78 | .datalen = sizeof(struct tcf_em_cmp), |
| 79 | .match = em_cmp_match, |
| 80 | .owner = THIS_MODULE, |
| 81 | .link = LIST_HEAD_INIT(em_cmp_ops.link) |
| 82 | }; |
| 83 | |
| 84 | static int __init init_em_cmp(void) |
| 85 | { |
| 86 | return tcf_em_register(&em_cmp_ops); |
| 87 | } |
| 88 | |
| 89 | static void __exit exit_em_cmp(void) |
| 90 | { |
| 91 | tcf_em_unregister(&em_cmp_ops); |
| 92 | } |
| 93 | |
| 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); |