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11#include <linux/etherdevice.h>
12#include <linux/module.h>
13#include <linux/netfilter/x_tables.h>
14#include <linux/netfilter_bridge/ebtables.h>
15#include <linux/netfilter_bridge/ebt_stp.h>
16
17#define BPDU_TYPE_CONFIG 0
18#define BPDU_TYPE_TCN 0x80
19
20struct stp_header {
21 u8 dsap;
22 u8 ssap;
23 u8 ctrl;
24 u8 pid;
25 u8 vers;
26 u8 type;
27};
28
29struct stp_config_pdu {
30 u8 flags;
31 u8 root[8];
32 u8 root_cost[4];
33 u8 sender[8];
34 u8 port[2];
35 u8 msg_age[2];
36 u8 max_age[2];
37 u8 hello_time[2];
38 u8 forward_delay[2];
39};
40
41#define NR16(p) (p[0] << 8 | p[1])
42#define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3])
43
44static bool ebt_filter_config(const struct ebt_stp_info *info,
45 const struct stp_config_pdu *stpc)
46{
47 const struct ebt_stp_config_info *c;
48 u16 v16;
49 u32 v32;
50
51 c = &info->config;
52 if ((info->bitmask & EBT_STP_FLAGS) &&
53 NF_INVF(info, EBT_STP_FLAGS, c->flags != stpc->flags))
54 return false;
55 if (info->bitmask & EBT_STP_ROOTPRIO) {
56 v16 = NR16(stpc->root);
57 if (NF_INVF(info, EBT_STP_ROOTPRIO,
58 v16 < c->root_priol || v16 > c->root_priou))
59 return false;
60 }
61 if (info->bitmask & EBT_STP_ROOTADDR) {
62 if (NF_INVF(info, EBT_STP_ROOTADDR,
63 !ether_addr_equal_masked(&stpc->root[2],
64 c->root_addr,
65 c->root_addrmsk)))
66 return false;
67 }
68 if (info->bitmask & EBT_STP_ROOTCOST) {
69 v32 = NR32(stpc->root_cost);
70 if (NF_INVF(info, EBT_STP_ROOTCOST,
71 v32 < c->root_costl || v32 > c->root_costu))
72 return false;
73 }
74 if (info->bitmask & EBT_STP_SENDERPRIO) {
75 v16 = NR16(stpc->sender);
76 if (NF_INVF(info, EBT_STP_SENDERPRIO,
77 v16 < c->sender_priol || v16 > c->sender_priou))
78 return false;
79 }
80 if (info->bitmask & EBT_STP_SENDERADDR) {
81 if (NF_INVF(info, EBT_STP_SENDERADDR,
82 !ether_addr_equal_masked(&stpc->sender[2],
83 c->sender_addr,
84 c->sender_addrmsk)))
85 return false;
86 }
87 if (info->bitmask & EBT_STP_PORT) {
88 v16 = NR16(stpc->port);
89 if (NF_INVF(info, EBT_STP_PORT,
90 v16 < c->portl || v16 > c->portu))
91 return false;
92 }
93 if (info->bitmask & EBT_STP_MSGAGE) {
94 v16 = NR16(stpc->msg_age);
95 if (NF_INVF(info, EBT_STP_MSGAGE,
96 v16 < c->msg_agel || v16 > c->msg_ageu))
97 return false;
98 }
99 if (info->bitmask & EBT_STP_MAXAGE) {
100 v16 = NR16(stpc->max_age);
101 if (NF_INVF(info, EBT_STP_MAXAGE,
102 v16 < c->max_agel || v16 > c->max_ageu))
103 return false;
104 }
105 if (info->bitmask & EBT_STP_HELLOTIME) {
106 v16 = NR16(stpc->hello_time);
107 if (NF_INVF(info, EBT_STP_HELLOTIME,
108 v16 < c->hello_timel || v16 > c->hello_timeu))
109 return false;
110 }
111 if (info->bitmask & EBT_STP_FWDD) {
112 v16 = NR16(stpc->forward_delay);
113 if (NF_INVF(info, EBT_STP_FWDD,
114 v16 < c->forward_delayl || v16 > c->forward_delayu))
115 return false;
116 }
117 return true;
118}
119
120static bool
121ebt_stp_mt(const struct sk_buff *skb, struct xt_action_param *par)
122{
123 const struct ebt_stp_info *info = par->matchinfo;
124 const struct stp_header *sp;
125 struct stp_header _stph;
126 const u8 header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
127
128 sp = skb_header_pointer(skb, 0, sizeof(_stph), &_stph);
129 if (sp == NULL)
130 return false;
131
132
133 if (memcmp(sp, header, sizeof(header)))
134 return false;
135
136 if ((info->bitmask & EBT_STP_TYPE) &&
137 NF_INVF(info, EBT_STP_TYPE, info->type != sp->type))
138 return false;
139
140 if (sp->type == BPDU_TYPE_CONFIG &&
141 info->bitmask & EBT_STP_CONFIG_MASK) {
142 const struct stp_config_pdu *st;
143 struct stp_config_pdu _stpc;
144
145 st = skb_header_pointer(skb, sizeof(_stph),
146 sizeof(_stpc), &_stpc);
147 if (st == NULL)
148 return false;
149 return ebt_filter_config(info, st);
150 }
151 return true;
152}
153
154static int ebt_stp_mt_check(const struct xt_mtchk_param *par)
155{
156 const struct ebt_stp_info *info = par->matchinfo;
157 const struct ebt_entry *e = par->entryinfo;
158
159 if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK ||
160 !(info->bitmask & EBT_STP_MASK))
161 return -EINVAL;
162
163 if (!par->nft_compat &&
164 (!ether_addr_equal(e->destmac, eth_stp_addr) ||
165 !(e->bitmask & EBT_DESTMAC) ||
166 !is_broadcast_ether_addr(e->destmsk)))
167 return -EINVAL;
168
169 return 0;
170}
171
172static struct xt_match ebt_stp_mt_reg __read_mostly = {
173 .name = "stp",
174 .revision = 0,
175 .family = NFPROTO_BRIDGE,
176 .match = ebt_stp_mt,
177 .checkentry = ebt_stp_mt_check,
178 .matchsize = sizeof(struct ebt_stp_info),
179 .me = THIS_MODULE,
180};
181
182static int __init ebt_stp_init(void)
183{
184 return xt_register_match(&ebt_stp_mt_reg);
185}
186
187static void __exit ebt_stp_fini(void)
188{
189 xt_unregister_match(&ebt_stp_mt_reg);
190}
191
192module_init(ebt_stp_init);
193module_exit(ebt_stp_fini);
194MODULE_DESCRIPTION("Ebtables: Spanning Tree Protocol packet match");
195MODULE_LICENSE("GPL");
196
