| /* |
| * Spanning tree protocol; BPDU handling |
| * Linux ethernet bridge |
| * |
| * Authors: |
| * Lennert Buytenhek <buytenh@gnu.org> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/netfilter_bridge.h> |
| #include <linux/etherdevice.h> |
| #include <linux/llc.h> |
| #include <net/net_namespace.h> |
| #include <net/llc.h> |
| #include <net/llc_pdu.h> |
| #include <asm/unaligned.h> |
| |
| #include "br_private.h" |
| #include "br_private_stp.h" |
| |
| #define STP_HZ 256 |
| |
| #define LLC_RESERVE sizeof(struct llc_pdu_un) |
| |
| static void br_send_bpdu(struct net_bridge_port *p, |
| const unsigned char *data, int length) |
| { |
| struct sk_buff *skb; |
| |
| skb = dev_alloc_skb(length+LLC_RESERVE); |
| if (!skb) |
| return; |
| |
| skb->dev = p->dev; |
| skb->protocol = htons(ETH_P_802_2); |
| |
| skb_reserve(skb, LLC_RESERVE); |
| memcpy(__skb_put(skb, length), data, length); |
| |
| llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN, |
| LLC_SAP_BSPAN, LLC_PDU_CMD); |
| llc_pdu_init_as_ui_cmd(skb); |
| |
| llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr); |
| |
| NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, |
| dev_queue_xmit); |
| } |
| |
| static inline void br_set_ticks(unsigned char *dest, int j) |
| { |
| unsigned long ticks = (STP_HZ * j)/ HZ; |
| |
| put_unaligned_be16(ticks, dest); |
| } |
| |
| static inline int br_get_ticks(const unsigned char *src) |
| { |
| unsigned long ticks = get_unaligned_be16(src); |
| |
| return DIV_ROUND_UP(ticks * HZ, STP_HZ); |
| } |
| |
| /* called under bridge lock */ |
| void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) |
| { |
| unsigned char buf[35]; |
| |
| if (p->br->stp_enabled != BR_KERNEL_STP) |
| return; |
| |
| buf[0] = 0; |
| buf[1] = 0; |
| buf[2] = 0; |
| buf[3] = BPDU_TYPE_CONFIG; |
| buf[4] = (bpdu->topology_change ? 0x01 : 0) | |
| (bpdu->topology_change_ack ? 0x80 : 0); |
| buf[5] = bpdu->root.prio[0]; |
| buf[6] = bpdu->root.prio[1]; |
| buf[7] = bpdu->root.addr[0]; |
| buf[8] = bpdu->root.addr[1]; |
| buf[9] = bpdu->root.addr[2]; |
| buf[10] = bpdu->root.addr[3]; |
| buf[11] = bpdu->root.addr[4]; |
| buf[12] = bpdu->root.addr[5]; |
| buf[13] = (bpdu->root_path_cost >> 24) & 0xFF; |
| buf[14] = (bpdu->root_path_cost >> 16) & 0xFF; |
| buf[15] = (bpdu->root_path_cost >> 8) & 0xFF; |
| buf[16] = bpdu->root_path_cost & 0xFF; |
| buf[17] = bpdu->bridge_id.prio[0]; |
| buf[18] = bpdu->bridge_id.prio[1]; |
| buf[19] = bpdu->bridge_id.addr[0]; |
| buf[20] = bpdu->bridge_id.addr[1]; |
| buf[21] = bpdu->bridge_id.addr[2]; |
| buf[22] = bpdu->bridge_id.addr[3]; |
| buf[23] = bpdu->bridge_id.addr[4]; |
| buf[24] = bpdu->bridge_id.addr[5]; |
| buf[25] = (bpdu->port_id >> 8) & 0xFF; |
| buf[26] = bpdu->port_id & 0xFF; |
| |
| br_set_ticks(buf+27, bpdu->message_age); |
| br_set_ticks(buf+29, bpdu->max_age); |
| br_set_ticks(buf+31, bpdu->hello_time); |
| br_set_ticks(buf+33, bpdu->forward_delay); |
| |
| br_send_bpdu(p, buf, 35); |
| } |
| |
| /* called under bridge lock */ |
| void br_send_tcn_bpdu(struct net_bridge_port *p) |
| { |
| unsigned char buf[4]; |
| |
| if (p->br->stp_enabled != BR_KERNEL_STP) |
| return; |
| |
| buf[0] = 0; |
| buf[1] = 0; |
| buf[2] = 0; |
| buf[3] = BPDU_TYPE_TCN; |
| br_send_bpdu(p, buf, 4); |
| } |
| |
| /* |
| * Called from llc. |
| * |
| * NO locks, but rcu_read_lock (preempt_disabled) |
| */ |
| int br_stp_rcv(struct sk_buff *skb, struct net_device *dev, |
| struct packet_type *pt, struct net_device *orig_dev) |
| { |
| const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb); |
| const unsigned char *dest = eth_hdr(skb)->h_dest; |
| struct net_bridge_port *p = rcu_dereference(dev->br_port); |
| struct net_bridge *br; |
| const unsigned char *buf; |
| |
| if (dev_net(dev) != &init_net) |
| goto err; |
| |
| if (!p) |
| goto err; |
| |
| if (pdu->ssap != LLC_SAP_BSPAN |
| || pdu->dsap != LLC_SAP_BSPAN |
| || pdu->ctrl_1 != LLC_PDU_TYPE_U) |
| goto err; |
| |
| if (!pskb_may_pull(skb, 4)) |
| goto err; |
| |
| /* compare of protocol id and version */ |
| buf = skb->data; |
| if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) |
| goto err; |
| |
| br = p->br; |
| spin_lock(&br->lock); |
| |
| if (br->stp_enabled != BR_KERNEL_STP) |
| goto out; |
| |
| if (!(br->dev->flags & IFF_UP)) |
| goto out; |
| |
| if (p->state == BR_STATE_DISABLED) |
| goto out; |
| |
| if (compare_ether_addr(dest, br->group_addr) != 0) |
| goto out; |
| |
| buf = skb_pull(skb, 3); |
| |
| if (buf[0] == BPDU_TYPE_CONFIG) { |
| struct br_config_bpdu bpdu; |
| |
| if (!pskb_may_pull(skb, 32)) |
| goto out; |
| |
| buf = skb->data; |
| bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; |
| bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; |
| |
| bpdu.root.prio[0] = buf[2]; |
| bpdu.root.prio[1] = buf[3]; |
| bpdu.root.addr[0] = buf[4]; |
| bpdu.root.addr[1] = buf[5]; |
| bpdu.root.addr[2] = buf[6]; |
| bpdu.root.addr[3] = buf[7]; |
| bpdu.root.addr[4] = buf[8]; |
| bpdu.root.addr[5] = buf[9]; |
| bpdu.root_path_cost = |
| (buf[10] << 24) | |
| (buf[11] << 16) | |
| (buf[12] << 8) | |
| buf[13]; |
| bpdu.bridge_id.prio[0] = buf[14]; |
| bpdu.bridge_id.prio[1] = buf[15]; |
| bpdu.bridge_id.addr[0] = buf[16]; |
| bpdu.bridge_id.addr[1] = buf[17]; |
| bpdu.bridge_id.addr[2] = buf[18]; |
| bpdu.bridge_id.addr[3] = buf[19]; |
| bpdu.bridge_id.addr[4] = buf[20]; |
| bpdu.bridge_id.addr[5] = buf[21]; |
| bpdu.port_id = (buf[22] << 8) | buf[23]; |
| |
| bpdu.message_age = br_get_ticks(buf+24); |
| bpdu.max_age = br_get_ticks(buf+26); |
| bpdu.hello_time = br_get_ticks(buf+28); |
| bpdu.forward_delay = br_get_ticks(buf+30); |
| |
| br_received_config_bpdu(p, &bpdu); |
| } |
| |
| else if (buf[0] == BPDU_TYPE_TCN) { |
| br_received_tcn_bpdu(p); |
| } |
| out: |
| spin_unlock(&br->lock); |
| err: |
| kfree_skb(skb); |
| return 0; |
| } |