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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Spanning tree protocol; BPDU handling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*/
#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>
#include <linux/etherdevice.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/stp.h>
#include <linux/unaligned.h>
#include "br_private.h"
#include "br_private_stp.h"
#define STP_HZ 256
#define LLC_RESERVE sizeof(struct llc_pdu_un)
static int br_send_bpdu_finish(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
return dev_queue_xmit(skb);
}
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->priority = TC_PRIO_CONTROL;
skb_reserve(skb, LLC_RESERVE);
__skb_put_data(skb, 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);
skb_reset_mac_header(skb);
NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
dev_net(p->dev), NULL, skb, NULL, skb->dev,
br_send_bpdu_finish);
}
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);
p->stp_xstats.tx_bpdu++;
}
/* 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);
p->stp_xstats.tx_tcn++;
}
/*
* Called from llc.
*
* NO locks, but rcu_read_lock
*/
void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
struct net_device *dev)
{
struct net_bridge_port *p;
struct net_bridge *br;
const unsigned char *buf;
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;
p = br_port_get_check_rcu(dev);
if (!p)
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 (!ether_addr_equal(eth_hdr(skb)->h_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) {
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);
if (bpdu.message_age > bpdu.max_age) {
if (net_ratelimit())
br_notice(p->br,
"port %u config from %pM"
" (message_age %ul > max_age %ul)\n",
p->port_no,
eth_hdr(skb)->h_source,
bpdu.message_age, bpdu.max_age);
goto out;
}
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);
}
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