// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Spanning tree protocol; BPDU handling
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* Linux ethernet bridge
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*
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* Authors:
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* Lennert Buytenhek <buytenh@gnu.org>
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*/
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#include <linux/kernel.h>
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#include <linux/netfilter_bridge.h>
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#include <linux/etherdevice.h>
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#include <linux/llc.h>
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#include <linux/slab.h>
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#include <linux/pkt_sched.h>
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#include <net/net_namespace.h>
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#include <net/llc.h>
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#include <net/llc_pdu.h>
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#include <net/stp.h>
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#include <asm/unaligned.h>
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#include "br_private.h"
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#include "br_private_stp.h"
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#define STP_HZ 256
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#define LLC_RESERVE sizeof(struct llc_pdu_un)
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static int br_send_bpdu_finish(struct net *net, struct sock *sk,
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struct sk_buff *skb)
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{
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return dev_queue_xmit(skb);
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}
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static void br_send_bpdu(struct net_bridge_port *p,
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const unsigned char *data, int length)
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{
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struct sk_buff *skb;
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skb = dev_alloc_skb(length+LLC_RESERVE);
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if (!skb)
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return;
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skb->dev = p->dev;
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skb->protocol = htons(ETH_P_802_2);
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skb->priority = TC_PRIO_CONTROL;
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skb_reserve(skb, LLC_RESERVE);
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__skb_put_data(skb, data, length);
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llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
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LLC_SAP_BSPAN, LLC_PDU_CMD);
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llc_pdu_init_as_ui_cmd(skb);
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llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
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skb_reset_mac_header(skb);
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NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
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dev_net(p->dev), NULL, skb, NULL, skb->dev,
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br_send_bpdu_finish);
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}
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static inline void br_set_ticks(unsigned char *dest, int j)
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{
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unsigned long ticks = (STP_HZ * j)/ HZ;
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put_unaligned_be16(ticks, dest);
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}
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static inline int br_get_ticks(const unsigned char *src)
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{
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unsigned long ticks = get_unaligned_be16(src);
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return DIV_ROUND_UP(ticks * HZ, STP_HZ);
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}
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/* called under bridge lock */
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void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
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{
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unsigned char buf[35];
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if (p->br->stp_enabled != BR_KERNEL_STP)
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return;
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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buf[3] = BPDU_TYPE_CONFIG;
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buf[4] = (bpdu->topology_change ? 0x01 : 0) |
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(bpdu->topology_change_ack ? 0x80 : 0);
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buf[5] = bpdu->root.prio[0];
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buf[6] = bpdu->root.prio[1];
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buf[7] = bpdu->root.addr[0];
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buf[8] = bpdu->root.addr[1];
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buf[9] = bpdu->root.addr[2];
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buf[10] = bpdu->root.addr[3];
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buf[11] = bpdu->root.addr[4];
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buf[12] = bpdu->root.addr[5];
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buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
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buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
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buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
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buf[16] = bpdu->root_path_cost & 0xFF;
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buf[17] = bpdu->bridge_id.prio[0];
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buf[18] = bpdu->bridge_id.prio[1];
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buf[19] = bpdu->bridge_id.addr[0];
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buf[20] = bpdu->bridge_id.addr[1];
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buf[21] = bpdu->bridge_id.addr[2];
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buf[22] = bpdu->bridge_id.addr[3];
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buf[23] = bpdu->bridge_id.addr[4];
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buf[24] = bpdu->bridge_id.addr[5];
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buf[25] = (bpdu->port_id >> 8) & 0xFF;
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buf[26] = bpdu->port_id & 0xFF;
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br_set_ticks(buf+27, bpdu->message_age);
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br_set_ticks(buf+29, bpdu->max_age);
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br_set_ticks(buf+31, bpdu->hello_time);
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br_set_ticks(buf+33, bpdu->forward_delay);
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br_send_bpdu(p, buf, 35);
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p->stp_xstats.tx_bpdu++;
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}
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/* called under bridge lock */
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void br_send_tcn_bpdu(struct net_bridge_port *p)
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{
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unsigned char buf[4];
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if (p->br->stp_enabled != BR_KERNEL_STP)
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return;
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buf[0] = 0;
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buf[1] = 0;
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buf[2] = 0;
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buf[3] = BPDU_TYPE_TCN;
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br_send_bpdu(p, buf, 4);
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p->stp_xstats.tx_tcn++;
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}
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/*
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* Called from llc.
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*
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* NO locks, but rcu_read_lock
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*/
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void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
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struct net_device *dev)
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{
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struct net_bridge_port *p;
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struct net_bridge *br;
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const unsigned char *buf;
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if (!pskb_may_pull(skb, 4))
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goto err;
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/* compare of protocol id and version */
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buf = skb->data;
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if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
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goto err;
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p = br_port_get_check_rcu(dev);
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if (!p)
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goto err;
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br = p->br;
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spin_lock(&br->lock);
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if (br->stp_enabled != BR_KERNEL_STP)
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goto out;
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if (!(br->dev->flags & IFF_UP))
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goto out;
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if (p->state == BR_STATE_DISABLED)
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goto out;
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if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
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goto out;
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if (p->flags & BR_BPDU_GUARD) {
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br_notice(br, "BPDU received on blocked port %u(%s)\n",
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(unsigned int) p->port_no, p->dev->name);
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br_stp_disable_port(p);
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goto out;
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}
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buf = skb_pull(skb, 3);
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if (buf[0] == BPDU_TYPE_CONFIG) {
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struct br_config_bpdu bpdu;
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if (!pskb_may_pull(skb, 32))
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goto out;
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buf = skb->data;
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bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
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bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
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bpdu.root.prio[0] = buf[2];
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bpdu.root.prio[1] = buf[3];
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bpdu.root.addr[0] = buf[4];
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bpdu.root.addr[1] = buf[5];
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bpdu.root.addr[2] = buf[6];
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bpdu.root.addr[3] = buf[7];
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bpdu.root.addr[4] = buf[8];
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bpdu.root.addr[5] = buf[9];
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bpdu.root_path_cost =
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(buf[10] << 24) |
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(buf[11] << 16) |
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(buf[12] << 8) |
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buf[13];
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bpdu.bridge_id.prio[0] = buf[14];
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bpdu.bridge_id.prio[1] = buf[15];
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bpdu.bridge_id.addr[0] = buf[16];
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bpdu.bridge_id.addr[1] = buf[17];
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bpdu.bridge_id.addr[2] = buf[18];
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bpdu.bridge_id.addr[3] = buf[19];
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bpdu.bridge_id.addr[4] = buf[20];
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bpdu.bridge_id.addr[5] = buf[21];
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bpdu.port_id = (buf[22] << 8) | buf[23];
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bpdu.message_age = br_get_ticks(buf+24);
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bpdu.max_age = br_get_ticks(buf+26);
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bpdu.hello_time = br_get_ticks(buf+28);
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bpdu.forward_delay = br_get_ticks(buf+30);
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if (bpdu.message_age > bpdu.max_age) {
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if (net_ratelimit())
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br_notice(p->br,
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"port %u config from %pM"
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" (message_age %ul > max_age %ul)\n",
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p->port_no,
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eth_hdr(skb)->h_source,
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bpdu.message_age, bpdu.max_age);
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goto out;
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}
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br_received_config_bpdu(p, &bpdu);
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} else if (buf[0] == BPDU_TYPE_TCN) {
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br_received_tcn_bpdu(p);
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}
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out:
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spin_unlock(&br->lock);
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err:
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kfree_skb(skb);
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}
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