1/* 2 * ebt_stp 3 * 4 * Authors: 5 * Bart De Schuymer <bdschuym@pandora.be> 6 * Stephen Hemminger <shemminger@osdl.org> 7 * 8 * July, 2003 9 */ 10 11#include <linux/netfilter_bridge/ebtables.h> 12#include <linux/netfilter_bridge/ebt_stp.h> 13#include <linux/etherdevice.h> 14#include <linux/module.h> 15 16#define BPDU_TYPE_CONFIG 0 17#define BPDU_TYPE_TCN 0x80 18 19struct stp_header { 20 uint8_t dsap; 21 uint8_t ssap; 22 uint8_t ctrl; 23 uint8_t pid; 24 uint8_t vers; 25 uint8_t type; 26}; 27 28struct stp_config_pdu { 29 uint8_t flags; 30 uint8_t root[8]; 31 uint8_t root_cost[4]; 32 uint8_t sender[8]; 33 uint8_t port[2]; 34 uint8_t msg_age[2]; 35 uint8_t max_age[2]; 36 uint8_t hello_time[2]; 37 uint8_t forward_delay[2]; 38}; 39 40#define NR16(p) (p[0] << 8 | p[1]) 41#define NR32(p) ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]) 42 43static int ebt_filter_config(struct ebt_stp_info *info, 44 struct stp_config_pdu *stpc) 45{ 46 struct ebt_stp_config_info *c; 47 uint16_t v16; 48 uint32_t v32; 49 int verdict, i; 50 51 c = &info->config; 52 if ((info->bitmask & EBT_STP_FLAGS) && 53 FWINV(c->flags != stpc->flags, EBT_STP_FLAGS)) 54 return EBT_NOMATCH; 55 if (info->bitmask & EBT_STP_ROOTPRIO) { 56 v16 = NR16(stpc->root); 57 if (FWINV(v16 < c->root_priol || 58 v16 > c->root_priou, EBT_STP_ROOTPRIO)) 59 return EBT_NOMATCH; 60 } 61 if (info->bitmask & EBT_STP_ROOTADDR) { 62 verdict = 0; 63 for (i = 0; i < 6; i++) 64 verdict |= (stpc->root[2+i] ^ c->root_addr[i]) & 65 c->root_addrmsk[i]; 66 if (FWINV(verdict != 0, EBT_STP_ROOTADDR)) 67 return EBT_NOMATCH; 68 } 69 if (info->bitmask & EBT_STP_ROOTCOST) { 70 v32 = NR32(stpc->root_cost); 71 if (FWINV(v32 < c->root_costl || 72 v32 > c->root_costu, EBT_STP_ROOTCOST)) 73 return EBT_NOMATCH; 74 } 75 if (info->bitmask & EBT_STP_SENDERPRIO) { 76 v16 = NR16(stpc->sender); 77 if (FWINV(v16 < c->sender_priol || 78 v16 > c->sender_priou, EBT_STP_SENDERPRIO)) 79 return EBT_NOMATCH; 80 } 81 if (info->bitmask & EBT_STP_SENDERADDR) { 82 verdict = 0; 83 for (i = 0; i < 6; i++) 84 verdict |= (stpc->sender[2+i] ^ c->sender_addr[i]) & 85 c->sender_addrmsk[i]; 86 if (FWINV(verdict != 0, EBT_STP_SENDERADDR)) 87 return EBT_NOMATCH; 88 } 89 if (info->bitmask & EBT_STP_PORT) { 90 v16 = NR16(stpc->port); 91 if (FWINV(v16 < c->portl || 92 v16 > c->portu, EBT_STP_PORT)) 93 return EBT_NOMATCH; 94 } 95 if (info->bitmask & EBT_STP_MSGAGE) { 96 v16 = NR16(stpc->msg_age); 97 if (FWINV(v16 < c->msg_agel || 98 v16 > c->msg_ageu, EBT_STP_MSGAGE)) 99 return EBT_NOMATCH; 100 } 101 if (info->bitmask & EBT_STP_MAXAGE) { 102 v16 = NR16(stpc->max_age); 103 if (FWINV(v16 < c->max_agel || 104 v16 > c->max_ageu, EBT_STP_MAXAGE)) 105 return EBT_NOMATCH; 106 } 107 if (info->bitmask & EBT_STP_HELLOTIME) { 108 v16 = NR16(stpc->hello_time); 109 if (FWINV(v16 < c->hello_timel || 110 v16 > c->hello_timeu, EBT_STP_HELLOTIME)) 111 return EBT_NOMATCH; 112 } 113 if (info->bitmask & EBT_STP_FWDD) { 114 v16 = NR16(stpc->forward_delay); 115 if (FWINV(v16 < c->forward_delayl || 116 v16 > c->forward_delayu, EBT_STP_FWDD)) 117 return EBT_NOMATCH; 118 } 119 return EBT_MATCH; 120} 121 122static int ebt_filter_stp(const struct sk_buff *skb, const struct net_device *in, 123 const struct net_device *out, const void *data, unsigned int datalen) 124{ 125 struct ebt_stp_info *info = (struct ebt_stp_info *)data; 126 struct stp_header _stph, *sp; 127 uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00}; 128 129 sp = skb_header_pointer(skb, 0, sizeof(_stph), &_stph); 130 if (sp == NULL) 131 return EBT_NOMATCH; 132 133 /* The stp code only considers these */ 134 if (memcmp(sp, header, sizeof(header))) 135 return EBT_NOMATCH; 136 137 if (info->bitmask & EBT_STP_TYPE 138 && FWINV(info->type != sp->type, EBT_STP_TYPE)) 139 return EBT_NOMATCH; 140 141 if (sp->type == BPDU_TYPE_CONFIG && 142 info->bitmask & EBT_STP_CONFIG_MASK) { 143 struct stp_config_pdu _stpc, *st; 144 145 st = skb_header_pointer(skb, sizeof(_stph), 146 sizeof(_stpc), &_stpc); 147 if (st == NULL) 148 return EBT_NOMATCH; 149 return ebt_filter_config(info, st); 150 } 151 return EBT_MATCH; 152} 153 154static int ebt_stp_check(const char *tablename, unsigned int hookmask, 155 const struct ebt_entry *e, void *data, unsigned int datalen) 156{ 157 struct ebt_stp_info *info = (struct ebt_stp_info *)data; 158 int len = EBT_ALIGN(sizeof(struct ebt_stp_info)); 159 uint8_t bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 160 uint8_t msk[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; 161 162 if (info->bitmask & ~EBT_STP_MASK || info->invflags & ~EBT_STP_MASK || 163 !(info->bitmask & EBT_STP_MASK)) 164 return -EINVAL; 165 if (datalen != len) 166 return -EINVAL; 167 /* Make sure the match only receives stp frames */ 168 if (compare_ether_addr(e->destmac, bridge_ula) || 169 compare_ether_addr(e->destmsk, msk) || !(e->bitmask & EBT_DESTMAC)) 170 return -EINVAL; 171 172 return 0; 173} 174 175static struct ebt_match filter_stp = 176{ 177 .name = EBT_STP_MATCH, 178 .match = ebt_filter_stp, 179 .check = ebt_stp_check, 180 .me = THIS_MODULE, 181}; 182 183static int __init ebt_stp_init(void) 184{ 185 return ebt_register_match(&filter_stp); 186} 187 188static void __exit ebt_stp_fini(void) 189{ 190 ebt_unregister_match(&filter_stp); 191} 192 193module_init(ebt_stp_init); 194module_exit(ebt_stp_fini); 195MODULE_LICENSE("GPL"); 196