// SPDX-License-Identifier: GPL-2.0-or-later /* * Spanning tree protocol; generic parts * Linux ethernet bridge * * Authors: * Lennert Buytenhek <buytenh@gnu.org> */ #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; 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; }