linux/net/bridge/br_stp_if.c
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   1/*
   2 *      Spanning tree protocol; interface code
   3 *      Linux ethernet bridge
   4 *
   5 *      Authors:
   6 *      Lennert Buytenhek               <buytenh@gnu.org>
   7 *
   8 *      This program is free software; you can redistribute it and/or
   9 *      modify it under the terms of the GNU General Public License
  10 *      as published by the Free Software Foundation; either version
  11 *      2 of the License, or (at your option) any later version.
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/kmod.h>
  16#include <linux/etherdevice.h>
  17#include <linux/rtnetlink.h>
  18
  19#include "br_private.h"
  20#include "br_private_stp.h"
  21
  22
  23/* Port id is composed of priority and port number.
  24 * NB: some bits of priority are dropped to
  25 *     make room for more ports.
  26 */
  27static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
  28{
  29        return ((u16)priority << BR_PORT_BITS)
  30                | (port_no & ((1<<BR_PORT_BITS)-1));
  31}
  32
  33#define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
  34
  35/* called under bridge lock */
  36void br_init_port(struct net_bridge_port *p)
  37{
  38        p->port_id = br_make_port_id(p->priority, p->port_no);
  39        br_become_designated_port(p);
  40        p->state = BR_STATE_BLOCKING;
  41        p->topology_change_ack = 0;
  42        p->config_pending = 0;
  43}
  44
  45/* called under bridge lock */
  46void br_stp_enable_bridge(struct net_bridge *br)
  47{
  48        struct net_bridge_port *p;
  49
  50        spin_lock_bh(&br->lock);
  51        mod_timer(&br->hello_timer, jiffies + br->hello_time);
  52        mod_timer(&br->gc_timer, jiffies + HZ/10);
  53
  54        br_config_bpdu_generation(br);
  55
  56        list_for_each_entry(p, &br->port_list, list) {
  57                if ((p->dev->flags & IFF_UP) && netif_carrier_ok(p->dev))
  58                        br_stp_enable_port(p);
  59
  60        }
  61        spin_unlock_bh(&br->lock);
  62}
  63
  64/* NO locks held */
  65void br_stp_disable_bridge(struct net_bridge *br)
  66{
  67        struct net_bridge_port *p;
  68
  69        spin_lock_bh(&br->lock);
  70        list_for_each_entry(p, &br->port_list, list) {
  71                if (p->state != BR_STATE_DISABLED)
  72                        br_stp_disable_port(p);
  73
  74        }
  75
  76        br->topology_change = 0;
  77        br->topology_change_detected = 0;
  78        spin_unlock_bh(&br->lock);
  79
  80        del_timer_sync(&br->hello_timer);
  81        del_timer_sync(&br->topology_change_timer);
  82        del_timer_sync(&br->tcn_timer);
  83        del_timer_sync(&br->gc_timer);
  84}
  85
  86/* called under bridge lock */
  87void br_stp_enable_port(struct net_bridge_port *p)
  88{
  89        br_init_port(p);
  90        br_port_state_selection(p->br);
  91        br_log_state(p);
  92        br_ifinfo_notify(RTM_NEWLINK, p);
  93}
  94
  95/* called under bridge lock */
  96void br_stp_disable_port(struct net_bridge_port *p)
  97{
  98        struct net_bridge *br = p->br;
  99        int wasroot;
 100
 101        wasroot = br_is_root_bridge(br);
 102        br_become_designated_port(p);
 103        p->state = BR_STATE_DISABLED;
 104        p->topology_change_ack = 0;
 105        p->config_pending = 0;
 106
 107        br_log_state(p);
 108        br_ifinfo_notify(RTM_NEWLINK, p);
 109
 110        del_timer(&p->message_age_timer);
 111        del_timer(&p->forward_delay_timer);
 112        del_timer(&p->hold_timer);
 113
 114        br_fdb_delete_by_port(br, p, 0);
 115        br_multicast_disable_port(p);
 116
 117        br_configuration_update(br);
 118
 119        br_port_state_selection(br);
 120
 121        if (br_is_root_bridge(br) && !wasroot)
 122                br_become_root_bridge(br);
 123}
 124
 125static void br_stp_start(struct net_bridge *br)
 126{
 127        int r;
 128        char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
 129        char *envp[] = { NULL };
 130
 131        r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 132        if (r == 0) {
 133                br->stp_enabled = BR_USER_STP;
 134                br_debug(br, "userspace STP started\n");
 135        } else {
 136                br->stp_enabled = BR_KERNEL_STP;
 137                br_debug(br, "using kernel STP\n");
 138
 139                /* To start timers on any ports left in blocking */
 140                spin_lock_bh(&br->lock);
 141                br_port_state_selection(br);
 142                spin_unlock_bh(&br->lock);
 143        }
 144}
 145
 146static void br_stp_stop(struct net_bridge *br)
 147{
 148        int r;
 149        char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
 150        char *envp[] = { NULL };
 151
 152        if (br->stp_enabled == BR_USER_STP) {
 153                r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 154                br_info(br, "userspace STP stopped, return code %d\n", r);
 155
 156                /* To start timers on any ports left in blocking */
 157                spin_lock_bh(&br->lock);
 158                br_port_state_selection(br);
 159                spin_unlock_bh(&br->lock);
 160        }
 161
 162        br->stp_enabled = BR_NO_STP;
 163}
 164
 165void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
 166{
 167        ASSERT_RTNL();
 168
 169        if (val) {
 170                if (br->stp_enabled == BR_NO_STP)
 171                        br_stp_start(br);
 172        } else {
 173                if (br->stp_enabled != BR_NO_STP)
 174                        br_stp_stop(br);
 175        }
 176}
 177
 178/* called under bridge lock */
 179void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 180{
 181        /* should be aligned on 2 bytes for ether_addr_equal() */
 182        unsigned short oldaddr_aligned[ETH_ALEN >> 1];
 183        unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
 184        struct net_bridge_port *p;
 185        int wasroot;
 186
 187        wasroot = br_is_root_bridge(br);
 188
 189        memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
 190        memcpy(br->bridge_id.addr, addr, ETH_ALEN);
 191        memcpy(br->dev->dev_addr, addr, ETH_ALEN);
 192
 193        list_for_each_entry(p, &br->port_list, list) {
 194                if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
 195                        memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
 196
 197                if (ether_addr_equal(p->designated_root.addr, oldaddr))
 198                        memcpy(p->designated_root.addr, addr, ETH_ALEN);
 199        }
 200
 201        br_configuration_update(br);
 202        br_port_state_selection(br);
 203        if (br_is_root_bridge(br) && !wasroot)
 204                br_become_root_bridge(br);
 205}
 206
 207/* should be aligned on 2 bytes for ether_addr_equal() */
 208static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
 209
 210/* called under bridge lock */
 211bool br_stp_recalculate_bridge_id(struct net_bridge *br)
 212{
 213        const unsigned char *br_mac_zero =
 214                        (const unsigned char *)br_mac_zero_aligned;
 215        const unsigned char *addr = br_mac_zero;
 216        struct net_bridge_port *p;
 217
 218        /* user has chosen a value so keep it */
 219        if (br->flags & BR_SET_MAC_ADDR)
 220                return false;
 221
 222        list_for_each_entry(p, &br->port_list, list) {
 223                if (addr == br_mac_zero ||
 224                    memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
 225                        addr = p->dev->dev_addr;
 226
 227        }
 228
 229        if (ether_addr_equal(br->bridge_id.addr, addr))
 230                return false;   /* no change */
 231
 232        br_stp_change_bridge_id(br, addr);
 233        return true;
 234}
 235
 236/* called under bridge lock */
 237void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
 238{
 239        struct net_bridge_port *p;
 240        int wasroot;
 241
 242        wasroot = br_is_root_bridge(br);
 243
 244        list_for_each_entry(p, &br->port_list, list) {
 245                if (p->state != BR_STATE_DISABLED &&
 246                    br_is_designated_port(p)) {
 247                        p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
 248                        p->designated_bridge.prio[1] = newprio & 0xFF;
 249                }
 250
 251        }
 252
 253        br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
 254        br->bridge_id.prio[1] = newprio & 0xFF;
 255        br_configuration_update(br);
 256        br_port_state_selection(br);
 257        if (br_is_root_bridge(br) && !wasroot)
 258                br_become_root_bridge(br);
 259}
 260
 261/* called under bridge lock */
 262int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 263{
 264        port_id new_port_id;
 265
 266        if (newprio > BR_MAX_PORT_PRIORITY)
 267                return -ERANGE;
 268
 269        new_port_id = br_make_port_id(newprio, p->port_no);
 270        if (br_is_designated_port(p))
 271                p->designated_port = new_port_id;
 272
 273        p->port_id = new_port_id;
 274        p->priority = newprio;
 275        if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
 276            p->port_id < p->designated_port) {
 277                br_become_designated_port(p);
 278                br_port_state_selection(p->br);
 279        }
 280
 281        return 0;
 282}
 283
 284/* called under bridge lock */
 285int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 286{
 287        if (path_cost < BR_MIN_PATH_COST ||
 288            path_cost > BR_MAX_PATH_COST)
 289                return -ERANGE;
 290
 291        p->path_cost = path_cost;
 292        br_configuration_update(p->br);
 293        br_port_state_selection(p->br);
 294        return 0;
 295}
 296
 297ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 298{
 299        return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 300               id->prio[0], id->prio[1],
 301               id->addr[0], id->addr[1], id->addr[2],
 302               id->addr[3], id->addr[4], id->addr[5]);
 303}
 304
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