1 /*
2 * ebt_stp
3 *
4 * Authors:
5 * Bart De Schuymer <bdschuym@pandora.be>
6 * Stephen Hemminger <shemminger@osdl.org>
7 *
8 * July, 2003
9 */
10
11 #include <linux/netfilter_bridge/ebtables.h>
12 #include <linux/netfilter_bridge/ebt_stp.h>
13 #include <linux/module.h>
14
15 #define BPDU_TYPE_CONFIG 0
16 #define BPDU_TYPE_TCN 0x80
17
18 struct stp_header {
19 uint8_t dsap;
20 uint8_t ssap;
21 uint8_t ctrl;
22 uint8_t pid;
23 uint8_t vers;
24 uint8_t type;
25 };
26
27 struct stp_config_pdu {
28 uint8_t flags;
29 uint8_t root[8];
30 uint8_t root_cost[4];
31 uint8_t sender[8];
32 uint8_t port[2];
33 uint8_t msg_age[2];
34 uint8_t max_age[2];
35 uint8_t hello_time[2];
36 uint8_t forward_delay[2];
37 };
38
39 #define NR16(p) (p[0] << 8 | p[1])
40 #define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3])
41
42 static int ebt_filter_config(struct ebt_stp_info *info,
43 struct stp_config_pdu *stpc)
44 {
45 struct ebt_stp_config_info *c;
46 uint16_t v16;
47 uint32_t v32;
48 int verdict, i;
49
50 c = &info->config;
51 if ((info->bitmask & EBT_STP_FLAGS) &&
52 FWINV(c->flags != stpc->flags, EBT_STP_FLAGS))
53 return EBT_NOMATCH;
54 if (info->bitmask & EBT_STP_ROOTPRIO) {
55 v16 = NR16(stpc->root);
56 if (FWINV(v16 < c->root_priol ||
57 v16 > c->root_priou, EBT_STP_ROOTPRIO))
58 return EBT_NOMATCH;
59 }
60 if (info->bitmask & EBT_STP_ROOTADDR) {
61 verdict = 0;
62 for (i = 0; i < 6; i++)
63 verdict |= (stpc->root[2+i] ^ c->root_addr[i]) &
64 c->root_addrmsk[i];
65 if (FWINV(verdict != 0, EBT_STP_ROOTADDR))
66 return EBT_NOMATCH;
67 }
68 if (info->bitmask & EBT_STP_ROOTCOST) {
69 v32 = NR32(stpc->root_cost);
70 if (FWINV(v32 < c->root_costl ||
71 v32 > c->root_costu, EBT_STP_ROOTCOST))
72 return EBT_NOMATCH;
73 }
74 if (info->bitmask & EBT_STP_SENDERPRIO) {
75 v16 = NR16(stpc->sender);
76 if (FWINV(v16 < c->sender_priol ||
77 v16 > c->sender_priou, EBT_STP_SENDERPRIO))
78 return EBT_NOMATCH;
79 }
80 if (info->bitmask & EBT_STP_SENDERADDR) {
81 verdict = 0;
82 for (i = 0; i < 6; i++)
83 verdict |= (stpc->sender[2+i] ^ c->sender_addr[i]) &
84 c->sender_addrmsk[i];
85 if (FWINV(verdict != 0, EBT_STP_SENDERADDR))
86 return EBT_NOMATCH;
87 }
88 if (info->bitmask & EBT_STP_PORT) {
89 v16 = NR16(stpc->port);
90 if (FWINV(v16 < c->portl ||
91 v16 > c->portu, EBT_STP_PORT))
92 return EBT_NOMATCH;
93 }
94 if (info->bitmask & EBT_STP_MSGAGE) {
95 v16 = NR16(stpc->msg_age);
96 if (FWINV(v16 < c->msg_agel ||
97 v16 > c->msg_ageu, EBT_STP_MSGAGE))
98 return EBT_NOMATCH;
99 }
100 if (info->bitmask & EBT_STP_MAXAGE) {
101 v16 = NR16(stpc->max_age);
102 if (FWINV(v16 < c->max_agel ||
103 v16 > c->max_ageu, EBT_STP_MAXAGE))
104 return EBT_NOMATCH;
105 }
106 if (info->bitmask & EBT_STP_HELLOTIME) {
107 v16 = NR16(stpc->hello_time);
108 if (FWINV(v16 < c->hello_timel ||
109 v16 > c->hello_timeu, EBT_STP_HELLOTIME))
110 return EBT_NOMATCH;
111 }
112 if (info->bitmask & EBT_STP_FWDD) {
113 v16 = NR16(stpc->forward_delay);
114 if (FWINV(v16 < c->forward_delayl ||
115 v16 > c->forward_delayu, EBT_STP_FWDD))
116 return EBT_NOMATCH;
117 }
118 return EBT_MATCH;
119 }
120
121 static int ebt_filter_stp(const struct sk_buff *skb, const struct net_device *in,
122 const struct net_device *out, const void *data, unsigned int datalen)
123 {
124 struct ebt_stp_info *info = (struct ebt_stp_info *)data;
125 struct stp_header _stph, *sp;
126 uint8_t 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 EBT_NOMATCH;
131
132 /* The stp code only considers these */
133 if (memcmp(sp, header, sizeof(header)))
134 return EBT_NOMATCH;
135
136 if (info->bitmask & EBT_STP_TYPE
137 && FWINV(info->type != sp->type, EBT_STP_TYPE))
138 return EBT_NOMATCH;
139
140 if (sp->type == BPDU_TYPE_CONFIG &&
141 info->bitmask & EBT_STP_CONFIG_MASK) {
142 struct stp_config_pdu _stpc, *st;
143
144 st = skb_header_pointer(skb, sizeof(_stph),
145 sizeof(_stpc), &_stpc);
146 if (st == NULL)
147 return EBT_NOMATCH;
148 return ebt_filter_config(info, st);
149 }
150 return EBT_MATCH;
151 }
152
153 static int ebt_stp_check(const char *tablename, unsigned int hookmask,
154 const struct ebt_entry *e, void *data, unsigned int datalen)
155 {
156 struct ebt_stp_info *info = (struct ebt_stp_info *)data;
157 int len = EBT_ALIGN(sizeof(struct ebt_stp_info));
158 uint8_t bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
159 uint8_t msk[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
160
161 if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK ||
162 !(info->bitmask & EBT_STP_MASK))
163 return -EINVAL;
164 if (datalen != len)
165 return -EINVAL;
166 /* Make sure the match only receives stp frames */
167 if (memcmp(e->destmac, bridge_ula, ETH_ALEN) ||
168 memcmp(e->destmsk, msk, ETH_ALEN) || !(e->bitmask & EBT_DESTMAC))
169 return -EINVAL;
170
171 return 0;
172 }
173
174 static struct ebt_match filter_stp =
175 {
176 .name = EBT_STP_MATCH,
177 .match = ebt_filter_stp,
178 .check = ebt_stp_check,
179 .me = THIS_MODULE,
180 };
181
182 static int __init init(void)
183 {
184 return ebt_register_match(&filter_stp);
185 }
186
187 static void __exit fini(void)
188 {
189 ebt_unregister_match(&filter_stp);
190 }
191
192 module_init(init);
193 module_exit(fini);
194 MODULE_LICENSE("GPL");
195
|
This page was automatically generated by the
LXR engine.
|