From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/bridge/netfilter/ebt_stp.c | 197 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 net/bridge/netfilter/ebt_stp.c (limited to 'net/bridge/netfilter/ebt_stp.c') diff --git a/net/bridge/netfilter/ebt_stp.c b/net/bridge/netfilter/ebt_stp.c new file mode 100644 index 000000000..071d87214 --- /dev/null +++ b/net/bridge/netfilter/ebt_stp.c @@ -0,0 +1,197 @@ +/* + * ebt_stp + * + * Authors: + * Bart De Schuymer + * Stephen Hemminger + * + * July, 2003 + */ +#include +#include +#include +#include +#include + +#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 (!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"); -- cgit v1.2.3-54-g00ecf