/* *  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 0x80struct 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;	uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};	if (skb_copy_bits(skb, 0, &stph, sizeof(stph)))		return EBT_NOMATCH;	/* The stp code only considers these */	if (memcmp(&stph, header, sizeof(header)))		return EBT_NOMATCH;	if (info->bitmask & EBT_STP_TYPE	    && FWINV(info->type != stph.type, EBT_STP_TYPE))		return EBT_NOMATCH;	if (stph.type == BPDU_TYPE_CONFIG &&	    info->bitmask & EBT_STP_CONFIG_MASK) {		struct stp_config_pdu stpc;		if (skb_copy_bits(skb, sizeof(stph), &stpc, sizeof(stpc)))		    return EBT_NOMATCH;		return ebt_filter_config(info, &stpc);	}	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");