br_stp_if.c

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/*
 *  Spanning tree protocol; interface code
 *  Linux ethernet bridge
 *
 *  Authors:
 *  Lennert Buytenhek       <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.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)
{
    p->port_id = br_make_port_id(p->priority, p->port_no);
    br_become_designated_port(p);
    p->state = BR_STATE_BLOCKING;
    p->topology_change_ack = 0;
    p->config_pending = 0;
}

/* called under bridge lock */
void br_stp_enable_bridge(struct net_bridge *br)
{
    struct net_bridge_port *p;

    spin_lock_bh(&br->lock);
    mod_timer(&br->hello_timer, jiffies + br->hello_time);
    mod_timer(&br->gc_timer, jiffies + HZ/10);

    br_config_bpdu_generation(br);

    list_for_each_entry(p, &br->port_list, list) {
        if ((p->dev->flags & IFF_UP) && netif_carrier_ok(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->topology_change = 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);
    del_timer_sync(&br->gc_timer);
}

/* 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_log_state(p);
    br_ifinfo_notify(RTM_NEWLINK, 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);
    p->state = BR_STATE_DISABLED;
    p->topology_change_ack = 0;
    p->config_pending = 0;

    br_log_state(p);
    br_ifinfo_notify(RTM_NEWLINK, p);

    del_timer(&p->message_age_timer);
    del_timer(&p->forward_delay_timer);
    del_timer(&p->hold_timer);

    br_fdb_delete_by_port(br, p, 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 void br_stp_start(struct net_bridge *br)
{
    int r;
    char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
    char *envp[] = { NULL };

    r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
    if (r == 0) {
        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 */
        spin_lock_bh(&br->lock);
        br_port_state_selection(br);
        spin_unlock_bh(&br->lock);
    }
}

static void br_stp_stop(struct net_bridge *br)
{
    int r;
    char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
    char *envp[] = { NULL };

    if (br->stp_enabled == BR_USER_STP) {
        r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
        br_info(br, "userspace STP stopped, return code %d\n", r);

        /* 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;
}

void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
{
    ASSERT_RTNL();

    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);
    }
}

/* 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);

    memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
    memcpy(br->bridge_id.addr, addr, ETH_ALEN);
    memcpy(br->dev->dev_addr, addr, ETH_ALEN);

    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->flags & BR_SET_MAC_ADDR)
        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;
}

/* called under bridge lock */
void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
{
    struct net_bridge_port *p;
    int wasroot;

    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);
}

/* 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->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]);
}