https://github.com/torvalds/linux
Tip revision: 39a8804455fb23f09157341d3ba7db6d7ae6ee76 authored by Linus Torvalds on 12 April 2015, 22:12:50 UTC
Linux 4.0
Linux 4.0
Tip revision: 39a8804
ebt_stp.c
/*
* 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 (!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");