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/*
* ebt_stp
*
* Authors:
* Bart De Schuymer <bdschuym@pandora.be>
* Stephen Hemminger <shemminger@osdl.org>
*
* July, 2003
*/
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_stp.h>
#include <linux/module.h>
#define BPDU_TYPE_CONFIG 0
#define BPDU_TYPE_TCN 0x80
struct stp_header {
uint8_t dsap;
uint8_t ssap;
uint8_t ctrl;
uint8_t pid;
uint8_t vers;
uint8_t type;
};
struct stp_config_pdu {
uint8_t flags;
uint8_t root[8];
uint8_t root_cost[4];
uint8_t sender[8];
uint8_t port[2];
uint8_t msg_age[2];
uint8_t max_age[2];
uint8_t hello_time[2];
uint8_t forward_delay[2];
};
#define NR16(p) (p[0] << 8 | p[1])
#define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3])
static int ebt_filter_config(struct ebt_stp_info *info,
struct stp_config_pdu *stpc)
{
struct ebt_stp_config_info *c;
uint16_t v16;
uint32_t v32;
int verdict, i;
c = &info->config;
if ((info->bitmask & EBT_STP_FLAGS) &&
FWINV(c->flags != stpc->flags, EBT_STP_FLAGS))
return EBT_NOMATCH;
if (info->bitmask & EBT_STP_ROOTPRIO) {
v16 = NR16(stpc->root);
if (FWINV(v16 < c->root_priol ||
v16 > c->root_priou, EBT_STP_ROOTPRIO))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_ROOTADDR) {
verdict = 0;
for (i = 0; i < 6; i++)
verdict |= (stpc->root[2+i] ^ c->root_addr[i]) &
c->root_addrmsk[i];
if (FWINV(verdict != 0, EBT_STP_ROOTADDR))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_ROOTCOST) {
v32 = NR32(stpc->root_cost);
if (FWINV(v32 < c->root_costl ||
v32 > c->root_costu, EBT_STP_ROOTCOST))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_SENDERPRIO) {
v16 = NR16(stpc->sender);
if (FWINV(v16 < c->sender_priol ||
v16 > c->sender_priou, EBT_STP_SENDERPRIO))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_SENDERADDR) {
verdict = 0;
for (i = 0; i < 6; i++)
verdict |= (stpc->sender[2+i] ^ c->sender_addr[i]) &
c->sender_addrmsk[i];
if (FWINV(verdict != 0, EBT_STP_SENDERADDR))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_PORT) {
v16 = NR16(stpc->port);
if (FWINV(v16 < c->portl ||
v16 > c->portu, EBT_STP_PORT))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_MSGAGE) {
v16 = NR16(stpc->msg_age);
if (FWINV(v16 < c->msg_agel ||
v16 > c->msg_ageu, EBT_STP_MSGAGE))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_MAXAGE) {
v16 = NR16(stpc->max_age);
if (FWINV(v16 < c->max_agel ||
v16 > c->max_ageu, EBT_STP_MAXAGE))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_HELLOTIME) {
v16 = NR16(stpc->hello_time);
if (FWINV(v16 < c->hello_timel ||
v16 > c->hello_timeu, EBT_STP_HELLOTIME))
return EBT_NOMATCH;
}
if (info->bitmask & EBT_STP_FWDD) {
v16 = NR16(stpc->forward_delay);
if (FWINV(v16 < c->forward_delayl ||
v16 > c->forward_delayu, EBT_STP_FWDD))
return EBT_NOMATCH;
}
return EBT_MATCH;
}
static int ebt_filter_stp(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const void *data, unsigned int datalen)
{
struct ebt_stp_info *info = (struct ebt_stp_info *)data;
struct stp_header _stph, *sp;
uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
sp = skb_header_pointer(skb, 0, sizeof(_stph), &_stph);
if (sp == NULL)
return EBT_NOMATCH;
/* The stp code only considers these */
if (memcmp(sp, header, sizeof(header)))
return EBT_NOMATCH;
if (info->bitmask & EBT_STP_TYPE
&& FWINV(info->type != sp->type, EBT_STP_TYPE))
return EBT_NOMATCH;
if (sp->type == BPDU_TYPE_CONFIG &&
info->bitmask & EBT_STP_CONFIG_MASK) {
struct stp_config_pdu _stpc, *st;
st = skb_header_pointer(skb, sizeof(_stph),
sizeof(_stpc), &_stpc);
if (st == NULL)
return EBT_NOMATCH;
return ebt_filter_config(info, st);
}
return EBT_MATCH;
}
static int ebt_stp_check(const char *tablename, unsigned int hookmask,
const struct ebt_entry *e, void *data, unsigned int datalen)
{
struct ebt_stp_info *info = (struct ebt_stp_info *)data;
int len = EBT_ALIGN(sizeof(struct ebt_stp_info));
uint8_t bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
uint8_t msk[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK ||
!(info->bitmask & EBT_STP_MASK))
return -EINVAL;
if (datalen != len)
return -EINVAL;
/* Make sure the match only receives stp frames */
if (memcmp(e->destmac, bridge_ula, ETH_ALEN) ||
memcmp(e->destmsk, msk, ETH_ALEN) || !(e->bitmask & EBT_DESTMAC))
return -EINVAL;
return 0;
}
static struct ebt_match filter_stp =
{
.name = EBT_STP_MATCH,
.match = ebt_filter_stp,
.check = ebt_stp_check,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ebt_register_match(&filter_stp);
}
static void __exit fini(void)
{
ebt_unregister_match(&filter_stp);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
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