// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Spanning tree protocol; generic parts
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <[email protected]>
*/
#include <linux/kernel.h>
#include <linux/rculist.h>
#include <net/switchdev.h>
#include "br_private.h"
#include "br_private_stp.h"
/* since time values in bpdu are in jiffies and then scaled (1/256)
* before sending, make sure that is at least one STP tick.
*/
#define MESSAGE_AGE_INCR ((HZ / 256) + 1)
static const char *const br_port_state_names[] = {
[BR_STATE_DISABLED] = "disabled",
[BR_STATE_LISTENING] = "listening",
[BR_STATE_LEARNING] = "learning",
[BR_STATE_FORWARDING] = "forwarding",
[BR_STATE_BLOCKING] = "blocking",
};
void br_set_state(struct net_bridge_port *p, unsigned int state)
{
struct switchdev_attr attr = {
.orig_dev = p->dev,
.id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
.flags = SWITCHDEV_F_DEFER,
.u.stp_state = state,
};
int err;
/* Don't change the state of the ports if they are driven by a different
* protocol.
*/
if (p->flags & BR_MRP_AWARE)
return;
p->state = state;
if (br_opt_get(p->br, BROPT_MST_ENABLED)) {
err = br_mst_set_state(p, 0, state, NULL);
if (err)
br_warn(p->br, "error setting MST state on port %u(%s)\n",
p->port_no, netdev_name(p->dev));
}
err = switchdev_port_attr_set(p->dev, &attr, NULL);
if (err && err != -EOPNOTSUPP)
br_warn(p->br, "error setting offload STP state on port %u(%s)\n",
(unsigned int) p->port_no, p->dev->name);
else
br_info(p->br, "port %u(%s) entered %s state\n",
(unsigned int) p->port_no, p->dev->name,
br_port_state_names[p->state]);
if (p->br->stp_enabled == BR_KERNEL_STP) {
switch (p->state) {
case BR_STATE_BLOCKING:
p->stp_xstats.transition_blk++;
break;
case BR_STATE_FORWARDING:
p->stp_xstats.transition_fwd++;
break;
}
}
}
u8 br_port_get_stp_state(const struct net_device *dev)
{
struct net_bridge_port *p;
ASSERT_RTNL();
p = br_port_get_rtnl(dev);
if (!p)
return BR_STATE_DISABLED;
return p->state;
}
EXPORT_SYMBOL_GPL(br_port_get_stp_state);
/* called under bridge lock */
struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
{
struct net_bridge_port *p;
list_for_each_entry_rcu(p, &br->port_list, list,
lockdep_is_held(&br->lock)) {
if (p->port_no == port_no)
return p;
}
return NULL;
}
/* called under bridge lock */
static int br_should_become_root_port(const struct net_bridge_port *p,
u16 root_port)
{
struct net_bridge *br;
struct net_bridge_port *rp;
int t;
br = p->br;
if (p->state == BR_STATE_DISABLED ||
br_is_designated_port(p))
return 0;
if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
return 0;
if (!root_port)
return 1;
rp = br_get_port(br, root_port);
t = memcmp(&p->designated_root, &rp->designated_root, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->designated_cost + p->path_cost <
rp->designated_cost + rp->path_cost)
return 1;
else if (p->designated_cost + p->path_cost >
rp->designated_cost + rp->path_cost)
return 0;
t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->designated_port < rp->designated_port)
return 1;
else if (p->designated_port > rp->designated_port)
return 0;
if (p->port_id < rp->port_id)
return 1;
return 0;
}
static void br_root_port_block(const struct net_bridge *br,
struct net_bridge_port *p)
{
br_notice(br, "port %u(%s) tried to become root port (blocked)",
(unsigned int) p->port_no, p->dev->name);
br_set_state(p, BR_STATE_LISTENING);
br_ifinfo_notify(RTM_NEWLINK, NULL, p);
if (br->forward_delay > 0)
mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
}
/* called under bridge lock */
static void br_root_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
u16 root_port = 0;
list_for_each_entry(p, &br->port_list, list) {
if (!br_should_become_root_port(p, root_port))
continue;
if (p->flags & BR_ROOT_BLOCK)
br_root_port_block(br, p);
else
root_port = p->port_no;
}
br->root_port = root_port;
if (!root_port) {
br->designated_root = br->bridge_id;
br->root_path_cost = 0;
} else {
p = br_get_port(br, root_port);
br->designated_root = p->designated_root;
br->root_path_cost = p->designated_cost + p->path_cost;
}
}
/* called under bridge lock */
void br_become_root_bridge(struct net_bridge *br)
{
br->max_age = br->bridge_max_age;
br->hello_time = br->bridge_hello_time;
br->forward_delay = br->bridge_forward_delay;
br_topology_change_detection(br);
del_timer(&br->tcn_timer);
if (br->dev->flags & IFF_UP) {
br_config_bpdu_generation(br);
mod_timer(&br->hello_timer, jiffies + br->hello_time);
}
}
/* called under bridge lock */
void br_transmit_config(struct net_bridge_port *p)
{
struct br_config_bpdu bpdu;
struct net_bridge *br;
if (timer_pending(&p->hold_timer)) {
p->config_pending = 1;
return;
}
br = p->br;
bpdu.topology_change = br->topology_change;
bpdu.topology_change_ack = p->topology_change_ack;
bpdu.root = br->designated_root;
bpdu.root_path_cost = br->root_path_cost;
bpdu.bridge_id = br->bridge_id;
bpdu.port_id = p->port_id;
if (br_is_root_bridge(br))
bpdu.message_age = 0;
else {
struct net_bridge_port *root
= br_get_port(br, br->root_port);
bpdu.message_age = (jiffies - root->designated_age)
+ MESSAGE_AGE_INCR;
}
bpdu.max_age = br->max_age;
bpdu.hello_time = br->hello_time;
bpdu.forward_delay = br->forward_delay;
if (bpdu.message_age < br->max_age) {
br_send_config_bpdu(p, &bpdu);
p->topology_change_ack = 0;
p->config_pending = 0;
if (p->br->stp_enabled == BR_KERNEL_STP)
mod_timer(&p->hold_timer,
round_jiffies(jiffies + BR_HOLD_TIME));
}
}
/* called under bridge lock */
static void br_record_config_information(struct net_bridge_port *p,
const struct br_config_bpdu *bpdu)
{
p->designated_root = bpdu->root;
p->designated_cost = bpdu->root_path_cost;
p->designated_bridge = bpdu->bridge_id;
p->designated_port = bpdu->port_id;
p->designated_age = jiffies - bpdu->message_age;
mod_timer(&p->message_age_timer, jiffies
+ (bpdu->max_age - bpdu->message_age));
}
/* called under bridge lock */
static void br_record_config_timeout_values(struct net_bridge *br,
const struct br_config_bpdu *bpdu)
{
br->max_age = bpdu->max_age;
br->hello_time = bpdu->hello_time;
br->forward_delay = bpdu->forward_delay;
__br_set_topology_change(br, bpdu->topology_change);
}
/* called under bridge lock */
void br_transmit_tcn(struct net_bridge *br)
{
struct net_bridge_port *p;
p = br_get_port(br, br->root_port);
if (p)
br_send_tcn_bpdu(p);
else
br_notice(br, "root port %u not found for topology notice\n",
br->root_port);
}
/* called under bridge lock */
static int br_should_become_designated_port(const struct net_bridge_port *p)
{
struct net_bridge *br;
int t;
br = p->br;
if (br_is_designated_port(p))
return 1;
if (memcmp(&p->designated_root, &br->designated_root, 8))
return 1;
if (br->root_path_cost < p->designated_cost)
return 1;
else if (br->root_path_cost > p->designated_cost)
return 0;
t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (p->port_id < p->designated_port)
return 1;
return 0;
}
/* called under bridge lock */
static void br_designated_port_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED &&
br_should_become_designated_port(p))
br_become_designated_port(p);
}
}
/* called under bridge lock */
static int br_supersedes_port_info(const struct net_bridge_port *p,
const struct br_config_bpdu *bpdu)
{
int t;
t = memcmp(&bpdu->root, &p->designated_root, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (bpdu->root_path_cost < p->designated_cost)
return 1;
else if (bpdu->root_path_cost > p->designated_cost)
return 0;
t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
if (t < 0)
return 1;
else if (t > 0)
return 0;
if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
return 1;
if (bpdu->port_id <= p->designated_port)
return 1;
return 0;
}
/* called under bridge lock */
static void br_topology_change_acknowledged(struct net_bridge *br)
{
br->topology_change_detected = 0;
del_timer(&br->tcn_timer);
}
/* called under bridge lock */
void br_topology_change_detection(struct net_bridge *br)
{
int isroot = br_is_root_bridge(br);
if (br->stp_enabled != BR_KERNEL_STP)
return;
br_info(br, "topology change detected, %s\n",
isroot ? "propagating" : "sending tcn bpdu");
if (isroot) {
__br_set_topology_change(br, 1);
mod_timer(&br->topology_change_timer, jiffies
+ br->bridge_forward_delay + br->bridge_max_age);
} else if (!br->topology_change_detected) {
br_transmit_tcn(br);
mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
}
br->topology_change_detected = 1;
}
/* called under bridge lock */
void br_config_bpdu_generation(struct net_bridge *br)
{
struct net_bridge_port *p;
list_for_each_entry(p, &br->port_list, list) {
if (p->state != BR_STATE_DISABLED &&
br_is_designated_port(p))
br_transmit_config(p);
}
}
/* called under bridge lock */
static void br_reply(struct net_bridge_port *p)
{
br_transmit_config(p);
}
/* called under bridge lock */
void br_configuration_update(struct net_bridge *br)
{
br_root_selection(br);
br_designated_port_selection(br);
}
/* called under bridge lock */
void br_become_designated_port(struct net_bridge_port *p)
{
struct net_bridge *br;
br = p->br;
p->designated_root = br->designated_root;
p->designated_cost = br->root_path_cost;
p->designated_bridge = br->bridge_id;
p->designated_port = p->port_id;
}
/* called under bridge lock */
static void br_make_blocking(struct net_bridge_port *p)
{
if (p->state != BR_STATE_DISABLED &&
p->state != BR_STATE_BLOCKING) {
if (p->state == BR_STATE_FORWARDING ||
p->state == BR_STATE_LEARNING)
br_topology_change_detection(p->br);
br_set_state(p, BR_STATE_BLOCKING);
br_ifinfo_notify(RTM_NEWLINK, NULL, p);
del_timer(&p->forward_delay_timer);
}
}
/* called under bridge lock */
static void br_make_forwarding(struct net_bridge_port *p)
{
struct net_bridge *br = p->br;
if (p->state != BR_STATE_BLOCKING)
return;
if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
br_set_state(p, BR_STATE_FORWARDING);
br_topology_change_detection(br);
del_timer(&p->forward_delay_timer);
} else if (br->stp_enabled == BR_KERNEL_STP)
br_set_state(p, BR_STATE_LISTENING);
else
br_set_state(p, BR_STATE_LEARNING);
br_ifinfo_notify(RTM_NEWLINK, NULL, p);
if (br->forward_delay != 0)
mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
}
/* called under bridge lock */
void br_port_state_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
unsigned int liveports = 0;
list_for_each_entry(p, &br->port_list, list) {
if (p->state == BR_STATE_DISABLED)
continue;
/* Don't change port states if userspace is handling STP */
if (br->stp_enabled != BR_USER_STP) {
if (p->port_no == br->root_port) {
p->config_pending = 0;
p->topology_change_ack = 0;
br_make_forwarding(p);
} else if (br_is_designated_port(p)) {
del_timer(&p->message_age_timer);
br_make_forwarding(p);
} else {
p->config_pending = 0;
p->topology_change_ack = 0;
br_make_blocking(p);
}
}
if (p->state != BR_STATE_BLOCKING)
br_multicast_enable_port(p);
/* Multicast is not disabled for the port when it goes in
* blocking state because the timers will expire and stop by
* themselves without sending more queries.
*/
if (p->state == BR_STATE_FORWARDING)
++liveports;
}
if (liveports == 0)
netif_carrier_off(br->dev);
else
netif_carrier_on(br->dev);
}
/* called under bridge lock */
static void br_topology_change_acknowledge(struct net_bridge_port *p)
{
p->topology_change_ack = 1;
br_transmit_config(p);
}
/* called under bridge lock */
void br_received_config_bpdu(struct net_bridge_port *p,
const struct br_config_bpdu *bpdu)
{
struct net_bridge *br;
int was_root;
p->stp_xstats.rx_bpdu++;
br = p->br;
was_root = br_is_root_bridge(br);
if (br_supersedes_port_info(p, bpdu)) {
br_record_config_information(p, bpdu);
br_configuration_update(br);
br_port_state_selection(br);
if (!br_is_root_bridge(br) && was_root) {
del_timer(&br->hello_timer);
if (br->topology_change_detected) {
del_timer(&br->topology_change_timer);
br_transmit_tcn(br);
mod_timer(&br->tcn_timer,
jiffies + br->bridge_hello_time);
}
}
if (p->port_no == br->root_port) {
br_record_config_timeout_values(br, bpdu);
br_config_bpdu_generation(br);
if (bpdu->topology_change_ack)
br_topology_change_acknowledged(br);
}
} else if (br_is_designated_port(p)) {
br_reply(p);
}
}
/* called under bridge lock */
void br_received_tcn_bpdu(struct net_bridge_port *p)
{
p->stp_xstats.rx_tcn++;
if (br_is_designated_port(p)) {
br_info(p->br, "port %u(%s) received tcn bpdu\n",
(unsigned int) p->port_no, p->dev->name);
br_topology_change_detection(p->br);
br_topology_change_acknowledge(p);
}
}
/* Change bridge STP parameter */
int br_set_hello_time(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
return -ERANGE;
spin_lock_bh(&br->lock);
br->bridge_hello_time = t;
if (br_is_root_bridge(br))
br->hello_time = br->bridge_hello_time;
spin_unlock_bh(&br->lock);
return 0;
}
int br_set_max_age(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
return -ERANGE;
spin_lock_bh(&br->lock);
br->bridge_max_age = t;
if (br_is_root_bridge(br))
br->max_age = br->bridge_max_age;
spin_unlock_bh(&br->lock);
return 0;
}
/* called under bridge lock */
int __set_ageing_time(struct net_device *dev, unsigned long t)
{
struct switchdev_attr attr = {
.orig_dev = dev,
.id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
.flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER,
.u.ageing_time = jiffies_to_clock_t(t),
};
int err;
err = switchdev_port_attr_set(dev, &attr, NULL);
if (err && err != -EOPNOTSUPP)
return err;
return 0;
}
/* Set time interval that dynamic forwarding entries live
* For pure software bridge, allow values outside the 802.1
* standard specification for special cases:
* 0 - entry never ages (all permanent)
* 1 - entry disappears (no persistence)
*
* Offloaded switch entries maybe more restrictive
*/
int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
{
unsigned long t = clock_t_to_jiffies(ageing_time);
int err;
err = __set_ageing_time(br->dev, t);
if (err)
return err;
spin_lock_bh(&br->lock);
br->bridge_ageing_time = t;
br->ageing_time = t;
spin_unlock_bh(&br->lock);
mod_delayed_work(system_long_wq, &br->gc_work, 0);
return 0;
}
clock_t br_get_ageing_time(const struct net_device *br_dev)
{
const struct net_bridge *br;
if (!netif_is_bridge_master(br_dev))
return 0;
br = netdev_priv(br_dev);
return jiffies_to_clock_t(br->ageing_time);
}
EXPORT_SYMBOL_GPL(br_get_ageing_time);
/* called under bridge lock */
void __br_set_topology_change(struct net_bridge *br, unsigned char val)
{
unsigned long t;
int err;
if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) {
/* On topology change, set the bridge ageing time to twice the
* forward delay. Otherwise, restore its default ageing time.
*/
if (val) {
t = 2 * br->forward_delay;
br_debug(br, "decreasing ageing time to %lu\n", t);
} else {
t = br->bridge_ageing_time;
br_debug(br, "restoring ageing time to %lu\n", t);
}
err = __set_ageing_time(br->dev, t);
if (err)
br_warn(br, "error offloading ageing time\n");
else
br->ageing_time = t;
}
br->topology_change = val;
}
void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
{
br->bridge_forward_delay = t;
if (br_is_root_bridge(br))
br->forward_delay = br->bridge_forward_delay;
}
int br_set_forward_delay(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
int err = -ERANGE;
spin_lock_bh(&br->lock);
if (br->stp_enabled != BR_NO_STP &&
(t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
goto unlock;
__br_set_forward_delay(br, t);
err = 0;
unlock:
spin_unlock_bh(&br->lock);
return err;
}
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