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/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");