| /* |
| * 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 int 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 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) |
| { |
| const struct ebt_stp_info *info = data; |
| 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 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) { |
| 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 EBT_NOMATCH; |
| return ebt_filter_config(info, st); |
| } |
| return EBT_MATCH; |
| } |
| |
| static bool ebt_stp_check(const char *tablename, unsigned int hookmask, |
| const struct ebt_entry *e, void *data, unsigned int datalen) |
| { |
| const struct ebt_stp_info *info = data; |
| const uint8_t bridge_ula[6] = {0x01, 0x80, 0xc2, 0x00, 0x00, 0x00}; |
| const 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 false; |
| /* Make sure the match only receives stp frames */ |
| if (compare_ether_addr(e->destmac, bridge_ula) || |
| compare_ether_addr(e->destmsk, msk) || !(e->bitmask & EBT_DESTMAC)) |
| return false; |
| |
| return true; |
| } |
| |
| static struct ebt_match filter_stp __read_mostly = { |
| .name = EBT_STP_MATCH, |
| .match = ebt_filter_stp, |
| .check = ebt_stp_check, |
| .matchsize = XT_ALIGN(sizeof(struct ebt_stp_info)), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ebt_stp_init(void) |
| { |
| return ebt_register_match(&filter_stp); |
| } |
| |
| static void __exit ebt_stp_fini(void) |
| { |
| ebt_unregister_match(&filter_stp); |
| } |
| |
| module_init(ebt_stp_init); |
| module_exit(ebt_stp_fini); |
| MODULE_DESCRIPTION("Ebtables: Spanning Tree Protocol packet match"); |
| MODULE_LICENSE("GPL"); |