// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Spanning tree protocol; interface code
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <[email protected]>
*/
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <net/switchdev.h>
#include "br_private.h"
#include "br_private_stp.h"
/* Port id is composed of priority and port number.
* NB: some bits of priority are dropped to
* make room for more ports.
*/
static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
{
return ((u16)priority << BR_PORT_BITS)
| (port_no & ((1<<BR_PORT_BITS)-1));
}
#define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
/* called under bridge lock */
void br_init_port(struct net_bridge_port *p)
{
int err;
p->port_id = br_make_port_id(p->priority, p->port_no);
br_become_designated_port(p);
br_set_state(p, BR_STATE_BLOCKING);
p->topology_change_ack = 0;
p->config_pending = 0;
err = __set_ageing_time(p->dev, p->br->ageing_time);
if (err)
netdev_err(p->dev, "failed to offload ageing time\n");
}
/* NO locks held */
void br_stp_enable_bridge(struct net_bridge *br)
{
struct net_bridge_port *p;
spin_lock_bh(&br->lock);
if (br->stp_enabled == BR_KERNEL_STP)
mod_timer(&br->hello_timer, jiffies + br->hello_time);
mod_delayed_work(system_long_wq, &br->gc_work, HZ / 10);
br_config_bpdu_generation(br);
list_for_each_entry(p, &br->port_list, list) {
if (netif_running(p->dev) && netif_oper_up(p->dev))
br_stp_enable_port(p);
}
spin_unlock_bh(&br->lock);
}
/* NO locks held */
void br_stp_disable_bridge(struct net_bridge *br)
{
struct net_bridge_port *p;
spin_lock_bh(&br->lock);
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED)
br_stp_disable_port(p);
}
__br_set_topology_change(br, 0);
br->topology_change_detected = 0;
spin_unlock_bh(&br->lock);
del_timer_sync(&br->hello_timer);
del_timer_sync(&br->topology_change_timer);
del_timer_sync(&br->tcn_timer);
cancel_delayed_work_sync(&br->gc_work);
}
/* called under bridge lock */
void br_stp_enable_port(struct net_bridge_port *p)
{
br_init_port(p);
br_port_state_selection(p->br);
br_ifinfo_notify(RTM_NEWLINK, NULL, p);
}
/* called under bridge lock */
void br_stp_disable_port(struct net_bridge_port *p)
{
struct net_bridge *br = p->br;
int wasroot;
wasroot = br_is_root_bridge(br);
br_become_designated_port(p);
br_set_state(p, BR_STATE_DISABLED);
p->topology_change_ack = 0;
p->config_pending = 0;
br_ifinfo_notify(RTM_NEWLINK, NULL, p);
del_timer(&p->message_age_timer);
del_timer(&p->forward_delay_timer);
del_timer(&p->hold_timer);
if (!rcu_access_pointer(p->backup_port))
br_fdb_delete_by_port(br, p, 0, 0);
br_multicast_disable_port(p);
br_configuration_update(br);
br_port_state_selection(br);
if (br_is_root_bridge(br) && !wasroot)
br_become_root_bridge(br);
}
static int br_stp_call_user(struct net_bridge *br, char *arg)
{
char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
char *envp[] = { NULL };
int rc;
/* call userspace STP and report program errors */
rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
if (rc > 0) {
if (rc & 0xff)
br_debug(br, BR_STP_PROG " received signal %d\n",
rc & 0x7f);
else
br_debug(br, BR_STP_PROG " exited with code %d\n",
(rc >> 8) & 0xff);
}
return rc;
}
static void br_stp_start(struct net_bridge *br)
{
int err = -ENOENT;
if (net_eq(dev_net(br->dev), &init_net))
err = br_stp_call_user(br, "start");
if (err && err != -ENOENT)
br_err(br, "failed to start userspace STP (%d)\n", err);
spin_lock_bh(&br->lock);
if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
__br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
__br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
if (!err) {
br->stp_enabled = BR_USER_STP;
br_debug(br, "userspace STP started\n");
} else {
br->stp_enabled = BR_KERNEL_STP;
br_debug(br, "using kernel STP\n");
/* To start timers on any ports left in blocking */
if (br->dev->flags & IFF_UP)
mod_timer(&br->hello_timer, jiffies + br->hello_time);
br_port_state_selection(br);
}
spin_unlock_bh(&br->lock);
}
static void br_stp_stop(struct net_bridge *br)
{
int err;
if (br->stp_enabled == BR_USER_STP) {
err = br_stp_call_user(br, "stop");
if (err)
br_err(br, "failed to stop userspace STP (%d)\n", err);
/* To start timers on any ports left in blocking */
spin_lock_bh(&br->lock);
br_port_state_selection(br);
spin_unlock_bh(&br->lock);
}
br->stp_enabled = BR_NO_STP;
}
int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
struct netlink_ext_ack *extack)
{
ASSERT_RTNL();
if (br_mrp_enabled(br)) {
NL_SET_ERR_MSG_MOD(extack,
"STP can't be enabled if MRP is already enabled");
return -EINVAL;
}
if (val) {
if (br->stp_enabled == BR_NO_STP)
br_stp_start(br);
} else {
if (br->stp_enabled != BR_NO_STP)
br_stp_stop(br);
}
return 0;
}
/* called under bridge lock */
void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
{
/* should be aligned on 2 bytes for ether_addr_equal() */
unsigned short oldaddr_aligned[ETH_ALEN >> 1];
unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
struct net_bridge_port *p;
int wasroot;
wasroot = br_is_root_bridge(br);
br_fdb_change_mac_address(br, addr);
memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
memcpy(br->bridge_id.addr, addr, ETH_ALEN);
eth_hw_addr_set(br->dev, addr);
list_for_each_entry(p, &br->port_list, list) {
if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
if (ether_addr_equal(p->designated_root.addr, oldaddr))
memcpy(p->designated_root.addr, addr, ETH_ALEN);
}
br_configuration_update(br);
br_port_state_selection(br);
if (br_is_root_bridge(br) && !wasroot)
br_become_root_bridge(br);
}
/* should be aligned on 2 bytes for ether_addr_equal() */
static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
/* called under bridge lock */
bool br_stp_recalculate_bridge_id(struct net_bridge *br)
{
const unsigned char *br_mac_zero =
(const unsigned char *)br_mac_zero_aligned;
const unsigned char *addr = br_mac_zero;
struct net_bridge_port *p;
/* user has chosen a value so keep it */
if (br->dev->addr_assign_type == NET_ADDR_SET)
return false;
list_for_each_entry(p, &br->port_list, list) {
if (addr == br_mac_zero ||
memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
addr = p->dev->dev_addr;
}
if (ether_addr_equal(br->bridge_id.addr, addr))
return false; /* no change */
br_stp_change_bridge_id(br, addr);
return true;
}
/* Acquires and releases bridge lock */
void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
{
struct net_bridge_port *p;
int wasroot;
spin_lock_bh(&br->lock);
wasroot = br_is_root_bridge(br);
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED &&
br_is_designated_port(p)) {
p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
p->designated_bridge.prio[1] = newprio & 0xFF;
}
}
br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
br->bridge_id.prio[1] = newprio & 0xFF;
br_configuration_update(br);
br_port_state_selection(br);
if (br_is_root_bridge(br) && !wasroot)
br_become_root_bridge(br);
spin_unlock_bh(&br->lock);
}
/* called under bridge lock */
int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
{
port_id new_port_id;
if (newprio > BR_MAX_PORT_PRIORITY)
return -ERANGE;
new_port_id = br_make_port_id(newprio, p->port_no);
if (br_is_designated_port(p))
p->designated_port = new_port_id;
p->port_id = new_port_id;
p->priority = newprio;
if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
p->port_id < p->designated_port) {
br_become_designated_port(p);
br_port_state_selection(p->br);
}
return 0;
}
/* called under bridge lock */
int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
{
if (path_cost < BR_MIN_PATH_COST ||
path_cost > BR_MAX_PATH_COST)
return -ERANGE;
p->flags |= BR_ADMIN_COST;
p->path_cost = path_cost;
br_configuration_update(p->br);
br_port_state_selection(p->br);
return 0;
}
ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
{
return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
id->prio[0], id->prio[1],
id->addr[0], id->addr[1], id->addr[2],
id->addr[3], id->addr[4], id->addr[5]);
}
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