40f36d37607d6a8dee0aca874003a2086ecd160d
[linux-2.6.git] / net / bridge / netfilter / ebt_stp.c
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/etherdevice.h>
14 #include <linux/module.h>
15
16 #define BPDU_TYPE_CONFIG 0
17 #define BPDU_TYPE_TCN 0x80
18
19 struct stp_header {
20         uint8_t dsap;
21         uint8_t ssap;
22         uint8_t ctrl;
23         uint8_t pid;
24         uint8_t vers;
25         uint8_t type;
26 };
27
28 struct stp_config_pdu {
29         uint8_t flags;
30         uint8_t root[8];
31         uint8_t root_cost[4];
32         uint8_t sender[8];
33         uint8_t port[2];
34         uint8_t msg_age[2];
35         uint8_t max_age[2];
36         uint8_t hello_time[2];
37         uint8_t forward_delay[2];
38 };
39
40 #define NR16(p) (p[0] << 8 | p[1])
41 #define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3])
42
43 static int ebt_filter_config(const struct ebt_stp_info *info,
44    const struct stp_config_pdu *stpc)
45 {
46         const struct ebt_stp_config_info *c;
47         uint16_t v16;
48         uint32_t v32;
49         int verdict, i;
50
51         c = &info->config;
52         if ((info->bitmask & EBT_STP_FLAGS) &&
53             FWINV(c->flags != stpc->flags, EBT_STP_FLAGS))
54                 return EBT_NOMATCH;
55         if (info->bitmask & EBT_STP_ROOTPRIO) {
56                 v16 = NR16(stpc->root);
57                 if (FWINV(v16 < c->root_priol ||
58                     v16 > c->root_priou, EBT_STP_ROOTPRIO))
59                         return EBT_NOMATCH;
60         }
61         if (info->bitmask & EBT_STP_ROOTADDR) {
62                 verdict = 0;
63                 for (i = 0; i < 6; i++)
64                         verdict |= (stpc->root[2+i] ^ c->root_addr[i]) &
65                                    c->root_addrmsk[i];
66                 if (FWINV(verdict != 0, EBT_STP_ROOTADDR))
67                         return EBT_NOMATCH;
68         }
69         if (info->bitmask & EBT_STP_ROOTCOST) {
70                 v32 = NR32(stpc->root_cost);
71                 if (FWINV(v32 < c->root_costl ||
72                     v32 > c->root_costu, EBT_STP_ROOTCOST))
73                         return EBT_NOMATCH;
74         }
75         if (info->bitmask & EBT_STP_SENDERPRIO) {
76                 v16 = NR16(stpc->sender);
77                 if (FWINV(v16 < c->sender_priol ||
78                     v16 > c->sender_priou, EBT_STP_SENDERPRIO))
79                         return EBT_NOMATCH;
80         }
81         if (info->bitmask & EBT_STP_SENDERADDR) {
82                 verdict = 0;
83                 for (i = 0; i < 6; i++)
84                         verdict |= (stpc->sender[2+i] ^ c->sender_addr[i]) &
85                                    c->sender_addrmsk[i];
86                 if (FWINV(verdict != 0, EBT_STP_SENDERADDR))
87                         return EBT_NOMATCH;
88         }
89         if (info->bitmask & EBT_STP_PORT) {
90                 v16 = NR16(stpc->port);
91                 if (FWINV(v16 < c->portl ||
92                     v16 > c->portu, EBT_STP_PORT))
93                         return EBT_NOMATCH;
94         }
95         if (info->bitmask & EBT_STP_MSGAGE) {
96                 v16 = NR16(stpc->msg_age);
97                 if (FWINV(v16 < c->msg_agel ||
98                     v16 > c->msg_ageu, EBT_STP_MSGAGE))
99                         return EBT_NOMATCH;
100         }
101         if (info->bitmask & EBT_STP_MAXAGE) {
102                 v16 = NR16(stpc->max_age);
103                 if (FWINV(v16 < c->max_agel ||
104                     v16 > c->max_ageu, EBT_STP_MAXAGE))
105                         return EBT_NOMATCH;
106         }
107         if (info->bitmask & EBT_STP_HELLOTIME) {
108                 v16 = NR16(stpc->hello_time);
109                 if (FWINV(v16 < c->hello_timel ||
110                     v16 > c->hello_timeu, EBT_STP_HELLOTIME))
111                         return EBT_NOMATCH;
112         }
113         if (info->bitmask & EBT_STP_FWDD) {
114                 v16 = NR16(stpc->forward_delay);
115                 if (FWINV(v16 < c->forward_delayl ||
116                     v16 > c->forward_delayu, EBT_STP_FWDD))
117                         return EBT_NOMATCH;
118         }
119         return EBT_MATCH;
120 }
121
122 static int ebt_filter_stp(const struct sk_buff *skb, const struct net_device *in,
123    const struct net_device *out, const void *data, unsigned int datalen)
124 {
125         const struct ebt_stp_info *info = data;
126         const struct stp_header *sp;
127         struct stp_header _stph;
128         const uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
129
130         sp = skb_header_pointer(skb, 0, sizeof(_stph), &_stph);
131         if (sp == NULL)
132                 return EBT_NOMATCH;
133
134         /* The stp code only considers these */
135         if (memcmp(sp, header, sizeof(header)))
136                 return EBT_NOMATCH;
137
138         if (info->bitmask & EBT_STP_TYPE
139             && FWINV(info->type != sp->type, EBT_STP_TYPE))
140                 return EBT_NOMATCH;
141
142         if (sp->type == BPDU_TYPE_CONFIG &&
143             info->bitmask & EBT_STP_CONFIG_MASK) {
144                 const struct stp_config_pdu *st;
145                 struct stp_config_pdu _stpc;
146
147                 st = skb_header_pointer(skb, sizeof(_stph),
148                                         sizeof(_stpc), &_stpc);
149                 if (st == NULL)
150                         return EBT_NOMATCH;
151                 return ebt_filter_config(info, st);
152         }
153         return EBT_MATCH;
154 }
155
156 static int ebt_stp_check(const char *tablename, unsigned int hookmask,
157    const struct ebt_entry *e, void *data, unsigned int datalen)
158 {
159         const struct ebt_stp_info *info = data;
160         const unsigned int len = EBT_ALIGN(sizeof(struct ebt_stp_info));
161         const uint8_t bridge_ula[6] = {0x01, 0x80, 0xc2, 0x00, 0x00, 0x00};
162         const uint8_t msk[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
163
164         if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK ||
165             !(info->bitmask & EBT_STP_MASK))
166                 return -EINVAL;
167         if (datalen != len)
168                 return -EINVAL;
169         /* Make sure the match only receives stp frames */
170         if (compare_ether_addr(e->destmac, bridge_ula) ||
171             compare_ether_addr(e->destmsk, msk) || !(e->bitmask & EBT_DESTMAC))
172                 return -EINVAL;
173
174         return 0;
175 }
176
177 static struct ebt_match filter_stp __read_mostly = {
178         .name           = EBT_STP_MATCH,
179         .match          = ebt_filter_stp,
180         .check          = ebt_stp_check,
181         .me             = THIS_MODULE,
182 };
183
184 static int __init ebt_stp_init(void)
185 {
186         return ebt_register_match(&filter_stp);
187 }
188
189 static void __exit ebt_stp_fini(void)
190 {
191         ebt_unregister_match(&filter_stp);
192 }
193
194 module_init(ebt_stp_init);
195 module_exit(ebt_stp_fini);
196 MODULE_DESCRIPTION("Ebtables: Spanning Tree Protocol packet match");
197 MODULE_LICENSE("GPL");