From a2e01a65cd7135dab26d27d4b589b2e5358bec99 Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Tue, 13 Nov 2012 07:53:07 +0000 Subject: [PATCH] bridge: implement BPDU blocking This is Linux bridge implementation of STP protection (Cisco BPDU guard/Juniper BPDU block). BPDU block disables the bridge port if a STP BPDU packet is received. Why would you want to do this? If running Spanning Tree on bridge, hostile devices on the network may send BPDU and cause network failure. Enabling bpdu block will detect and stop this. How to recover the port? The port will be restarted if link is brought down, or removed and reattached. For example: # ip li set dev eth0 down; ip li set dev eth0 up Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- include/uapi/linux/if_link.h | 1 + net/bridge/br_netlink.c | 6 +++++- net/bridge/br_private.h | 1 + net/bridge/br_stp_bpdu.c | 7 +++++++ net/bridge/br_sysfs_if.c | 2 ++ 5 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h index 96f7cf4..5e871e4 100644 --- a/include/uapi/linux/if_link.h +++ b/include/uapi/linux/if_link.h @@ -216,6 +216,7 @@ enum { IFLA_BRPORT_PRIORITY, /* " priority */ IFLA_BRPORT_COST, /* " cost */ IFLA_BRPORT_MODE, /* mode (hairpin) */ + IFLA_BRPORT_GUARD, /* bpdu guard */ __IFLA_BRPORT_MAX }; #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1) diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index 0188a2f..c331e28 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -26,6 +26,7 @@ static inline size_t br_port_info_size(void) + nla_total_size(2) /* IFLA_BRPORT_PRIORITY */ + nla_total_size(4) /* IFLA_BRPORT_COST */ + nla_total_size(1) /* IFLA_BRPORT_MODE */ + + nla_total_size(1) /* IFLA_BRPORT_GUARD */ + 0; } @@ -49,7 +50,8 @@ static int br_port_fill_attrs(struct sk_buff *skb, if (nla_put_u8(skb, IFLA_BRPORT_STATE, p->state) || nla_put_u16(skb, IFLA_BRPORT_PRIORITY, p->priority) || nla_put_u32(skb, IFLA_BRPORT_COST, p->path_cost) || - nla_put_u8(skb, IFLA_BRPORT_MODE, mode)) + nla_put_u8(skb, IFLA_BRPORT_MODE, mode) || + nla_put_u8(skb, IFLA_BRPORT_GUARD, !!(p->flags & BR_BPDU_GUARD))) return -EMSGSIZE; return 0; @@ -162,6 +164,7 @@ static const struct nla_policy ifla_brport_policy[IFLA_BRPORT_MAX + 1] = { [IFLA_BRPORT_COST] = { .type = NLA_U32 }, [IFLA_BRPORT_PRIORITY] = { .type = NLA_U16 }, [IFLA_BRPORT_MODE] = { .type = NLA_U8 }, + [IFLA_BRPORT_GUARD] = { .type = NLA_U8 }, }; /* Change the state of the port and notify spanning tree */ @@ -203,6 +206,7 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[]) int err; br_set_port_flag(p, tb, IFLA_BRPORT_MODE, BR_HAIRPIN_MODE); + br_set_port_flag(p, tb, IFLA_BRPORT_GUARD, BR_BPDU_GUARD); if (tb[IFLA_BRPORT_COST]) { err = br_stp_set_path_cost(p, nla_get_u32(tb[IFLA_BRPORT_COST])); diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 22111ff..c92b080 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -135,6 +135,7 @@ struct net_bridge_port unsigned long flags; #define BR_HAIRPIN_MODE 0x00000001 +#define BR_BPDU_GUARD 0x00000002 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING u32 multicast_startup_queries_sent; diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c index fd30a60..7f884e3 100644 --- a/net/bridge/br_stp_bpdu.c +++ b/net/bridge/br_stp_bpdu.c @@ -170,6 +170,13 @@ void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb, if (!ether_addr_equal(dest, br->group_addr)) goto out; + if (p->flags & BR_BPDU_GUARD) { + br_notice(br, "BPDU received on blocked port %u(%s)\n", + (unsigned int) p->port_no, p->dev->name); + br_stp_disable_port(p); + goto out; + } + buf = skb_pull(skb, 3); if (buf[0] == BPDU_TYPE_CONFIG) { diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c index f26173d..d1dfa40 100644 --- a/net/bridge/br_sysfs_if.c +++ b/net/bridge/br_sysfs_if.c @@ -156,6 +156,7 @@ static int store_flush(struct net_bridge_port *p, unsigned long v) static BRPORT_ATTR(flush, S_IWUSR, NULL, store_flush); BRPORT_ATTR_FLAG(hairpin_mode, BR_HAIRPIN_MODE); +BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD); #ifdef CONFIG_BRIDGE_IGMP_SNOOPING static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf) @@ -189,6 +190,7 @@ static const struct brport_attribute *brport_attrs[] = { &brport_attr_hold_timer, &brport_attr_flush, &brport_attr_hairpin_mode, + &brport_attr_bpdu_guard, #ifdef CONFIG_BRIDGE_IGMP_SNOOPING &brport_attr_multicast_router, #endif -- 2.7.4