[BRIDGE/EBTABLES]: Add stp packet matching.

include/linux/netfilter_bridge/ebt_stp.h

+#ifndef __LINUX_BRIDGE_EBT_STP_H
+#define __LINUX_BRIDGE_EBT_STP_H
+
+#define EBT_STP_TYPE		0x0001
+
+#define EBT_STP_FLAGS		0x0002
+#define EBT_STP_ROOTPRIO	0x0004
+#define EBT_STP_ROOTADDR	0x0008
+#define EBT_STP_ROOTCOST	0x0010
+#define EBT_STP_SENDERPRIO	0x0020
+#define EBT_STP_SENDERADDR	0x0040
+#define EBT_STP_PORT		0x0080
+#define EBT_STP_MSGAGE		0x0100
+#define EBT_STP_MAXAGE		0x0200
+#define EBT_STP_HELLOTIME	0x0400
+#define EBT_STP_FWDD		0x0800
+
+#define EBT_STP_MASK		0x0fff
+#define EBT_STP_CONFIG_MASK	0x0ffe
+
+#define EBT_STP_MATCH "stp"
+
+struct ebt_stp_config_info
+{
+	uint8_t flags;
+	uint16_t root_priol, root_priou;
+	char root_addr[6], root_addrmsk[6];
+	uint32_t root_costl, root_costu;
+	uint16_t sender_priol, sender_priou;
+	char sender_addr[6], sender_addrmsk[6];
+	uint16_t portl, portu;
+	uint16_t msg_agel, msg_ageu;
+	uint16_t max_agel, max_ageu;
+	uint16_t hello_timel, hello_timeu;
+	uint16_t forward_delayl, forward_delayu;
+};
+
+struct ebt_stp_info
+{
+	uint8_t type;
+	struct ebt_stp_config_info config;
+	uint16_t bitmask;
+	uint16_t invflags;
+};
+
+#endif

net/bridge/netfilter/Kconfig

@@ -103,6 +103,16 @@ config BRIDGE_EBT_PKTTYPE
 	  If you want to compile it as a module, say M here and read
 	  <file:Documentation/modules.txt>.  If unsure, say `N'.
 
+config BRIDGE_EBT_STP
+	tristate "ebt: STP filter support"
+	depends on BRIDGE_NF_EBTABLES
+	help
+	  This option adds the Spanning Tree Protocol match, which
+	  allows STP header field filtering.
+
+	  If you want to compile it as a module, say M here and read
+	  <file:Documentation/modules.txt>.  If unsure, say `N'.
+
 config BRIDGE_EBT_SNAT
 	tristate "ebt: snat target support"
 	depends on BRIDGE_NF_EBTABLES

net/bridge/netfilter/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_BRIDGE_EBT_ARP) += ebt_arp.o
 obj-$(CONFIG_BRIDGE_EBT_VLAN) += ebt_vlan.o
 obj-$(CONFIG_BRIDGE_EBT_MARK) += ebt_mark_m.o
 obj-$(CONFIG_BRIDGE_EBT_PKTTYPE) += ebt_pkttype.o
+obj-$(CONFIG_BRIDGE_EBT_STP) += ebt_stp.o
 obj-$(CONFIG_BRIDGE_EBT_LOG) += ebt_log.o
 obj-$(CONFIG_BRIDGE_EBT_SNAT) += ebt_snat.o
 obj-$(CONFIG_BRIDGE_EBT_DNAT) += ebt_dnat.o

net/bridge/netfilter/ebt_stp.c

+/*
+ *  ebt_stp
+ *
+ *	Authors:
+ *	Bart De Schuymer <bdschuym@pandora.be>
+ *	Stephen Hemminger <shemminger@osdl.org>
+ *
+ *  July, 2003
+ */
+
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_bridge/ebt_stp.h>
+#include <linux/module.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(struct ebt_stp_info *info,
+   struct stp_config_pdu *stpc)
+{
+	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)
+{
+	struct ebt_stp_info *info = (struct ebt_stp_info *)data;
+	struct stp_header stph;
+	uint8_t header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
+	if (skb_copy_bits(skb, 0, &stph, sizeof(stph)))
+		return EBT_NOMATCH;
+
+	/* The stp code only considers these */
+	if (memcmp(&stph, header, sizeof(header)))
+		return EBT_NOMATCH;
+
+	if (info->bitmask & EBT_STP_TYPE
+	    && FWINV(info->type != stph.type, EBT_STP_TYPE))
+		return EBT_NOMATCH;
+
+	if (stph.type == BPDU_TYPE_CONFIG &&
+	    info->bitmask & EBT_STP_CONFIG_MASK) {
+		struct stp_config_pdu stpc;
+
+		if (skb_copy_bits(skb, sizeof(stph), &stpc, sizeof(stpc)))
+		    return EBT_NOMATCH;
+		return ebt_filter_config(info, &stpc);
+	}
+	return EBT_MATCH;
+}
+
+static int ebt_stp_check(const char *tablename, unsigned int hookmask,
+   const struct ebt_entry *e, void *data, unsigned int datalen)
+{
+	struct ebt_stp_info *info = (struct ebt_stp_info *)data;
+	int len = sizeof(struct ebt_stp_info);
+	uint8_t bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
+	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 -EINVAL;
+	if (datalen != len)
+		return -EINVAL;
+	/* Make sure the match only receives stp frames */
+	if (memcmp(e->destmac, bridge_ula, ETH_ALEN) ||
+	    memcmp(e->destmsk, msk, ETH_ALEN) || !(e->bitmask & EBT_DESTMAC))
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct ebt_match filter_stp =
+{
+	.name		= EBT_STP_MATCH,
+	.match		= ebt_filter_stp,
+	.check		= ebt_stp_check,
+	.me		= THIS_MODULE,
+};
+
+static int __init init(void)
+{
+	return ebt_register_match(&filter_stp);
+}
+
+static void __exit fini(void)
+{
+	ebt_unregister_match(&filter_stp);
+}
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");