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- /*
- * ebt_stp
- *
- * Authors:
- * Bart De Schuymer <bdschuym@pandora.be>
- * Stephen Hemminger <shemminger@osdl.org>
- *
- * July, 2003
- */
- #include <linux/etherdevice.h>
- #include <linux/module.h>
- #include <linux/netfilter/x_tables.h>
- #include <linux/netfilter_bridge/ebtables.h>
- #include <linux/netfilter_bridge/ebt_stp.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 bool ebt_filter_config(const struct ebt_stp_info *info,
- const struct stp_config_pdu *stpc)
- {
- const 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 false;
- if (info->bitmask & EBT_STP_ROOTPRIO) {
- v16 = NR16(stpc->root);
- if (FWINV(v16 < c->root_priol ||
- v16 > c->root_priou, EBT_STP_ROOTPRIO))
- return false;
- }
- 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 false;
- }
- 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 false;
- }
- if (info->bitmask & EBT_STP_SENDERPRIO) {
- v16 = NR16(stpc->sender);
- if (FWINV(v16 < c->sender_priol ||
- v16 > c->sender_priou, EBT_STP_SENDERPRIO))
- return false;
- }
- 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 false;
- }
- if (info->bitmask & EBT_STP_PORT) {
- v16 = NR16(stpc->port);
- if (FWINV(v16 < c->portl ||
- v16 > c->portu, EBT_STP_PORT))
- return false;
- }
- 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 false;
- }
- 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 false;
- }
- 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 false;
- }
- 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 false;
- }
- return true;
- }
- static bool
- ebt_stp_mt(const struct sk_buff *skb, struct xt_action_param *par)
- {
- const struct ebt_stp_info *info = par->matchinfo;
- const struct stp_header *sp;
- struct stp_header _stph;
- const uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
- sp = skb_header_pointer(skb, 0, sizeof(_stph), &_stph);
- if (sp == NULL)
- return false;
- /* The stp code only considers these */
- if (memcmp(sp, header, sizeof(header)))
- return false;
- if (info->bitmask & EBT_STP_TYPE &&
- FWINV(info->type != sp->type, EBT_STP_TYPE))
- return false;
- if (sp->type == BPDU_TYPE_CONFIG &&
- info->bitmask & EBT_STP_CONFIG_MASK) {
- const struct stp_config_pdu *st;
- struct stp_config_pdu _stpc;
- st = skb_header_pointer(skb, sizeof(_stph),
- sizeof(_stpc), &_stpc);
- if (st == NULL)
- return false;
- return ebt_filter_config(info, st);
- }
- return true;
- }
- static int ebt_stp_mt_check(const struct xt_mtchk_param *par)
- {
- const struct ebt_stp_info *info = par->matchinfo;
- const uint8_t bridge_ula[6] = {0x01, 0x80, 0xc2, 0x00, 0x00, 0x00};
- const uint8_t msk[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
- const struct ebt_entry *e = par->entryinfo;
- if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK ||
- !(info->bitmask & EBT_STP_MASK))
- return -EINVAL;
- /* Make sure the match only receives stp frames */
- if (!par->nft_compat &&
- (!ether_addr_equal(e->destmac, bridge_ula) ||
- !ether_addr_equal(e->destmsk, msk) ||
- !(e->bitmask & EBT_DESTMAC)))
- return -EINVAL;
- return 0;
- }
- static struct xt_match ebt_stp_mt_reg __read_mostly = {
- .name = "stp",
- .revision = 0,
- .family = NFPROTO_BRIDGE,
- .match = ebt_stp_mt,
- .checkentry = ebt_stp_mt_check,
- .matchsize = sizeof(struct ebt_stp_info),
- .me = THIS_MODULE,
- };
- static int __init ebt_stp_init(void)
- {
- return xt_register_match(&ebt_stp_mt_reg);
- }
- static void __exit ebt_stp_fini(void)
- {
- xt_unregister_match(&ebt_stp_mt_reg);
- }
- module_init(ebt_stp_init);
- module_exit(ebt_stp_fini);
- MODULE_DESCRIPTION("Ebtables: Spanning Tree Protocol packet match");
- MODULE_LICENSE("GPL");
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