net/bridge/br_stp_if.c

   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 #include <net/switchdev.h>
  19
  20 #include "br_private.h"
  21 #include "br_private_stp.h"
  22
  23
  24 /* Port id is composed of priority and port number.
  25  * NB: some bits of priority are dropped to
  26  *     make room for more ports.
  27  */
  28 static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
  29 {
  30         return ((u16)priority << BR_PORT_BITS)
  31                 | (port_no & ((1<<BR_PORT_BITS)-1));
  32 }
  33
  34 #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
  35
  36 /* called under bridge lock */
  37 void br_init_port(struct net_bridge_port *p)
  38 {
  39         int err;
  40
  41         p->port_id = br_make_port_id(p->priority, p->port_no);
  42         br_become_designated_port(p);
  43         br_set_state(p, BR_STATE_BLOCKING);
  44         p->topology_change_ack = 0;
  45         p->config_pending = 0;
  46
  47         err = __set_ageing_time(p->dev, p->br->ageing_time);
  48         if (err)
  49                 netdev_err(p->dev, "failed to offload ageing time\n");
  50 }
  51
  52 /* NO locks held */
  53 void br_stp_enable_bridge(struct net_bridge *br)
  54 {
  55         struct net_bridge_port *p;
  56
  57         spin_lock_bh(&br->lock);
  58         if (br->stp_enabled == BR_KERNEL_STP)
  59                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
  60         mod_delayed_work(system_long_wq, &br->gc_work, HZ / 10);
  61
  62         br_config_bpdu_generation(br);
  63
  64         list_for_each_entry(p, &br->port_list, list) {
  65                 if (netif_running(p->dev) && netif_oper_up(p->dev))
  66                         br_stp_enable_port(p);
  67
  68         }
  69         spin_unlock_bh(&br->lock);
  70 }
  71
  72 /* NO locks held */
  73 void br_stp_disable_bridge(struct net_bridge *br)
  74 {
  75         struct net_bridge_port *p;
  76
  77         spin_lock_bh(&br->lock);
  78         list_for_each_entry(p, &br->port_list, list) {
  79                 if (p->state != BR_STATE_DISABLED)
  80                         br_stp_disable_port(p);
  81
  82         }
  83
  84         __br_set_topology_change(br, 0);
  85         br->topology_change_detected = 0;
  86         spin_unlock_bh(&br->lock);
  87
  88         del_timer_sync(&br->hello_timer);
  89         del_timer_sync(&br->topology_change_timer);
  90         del_timer_sync(&br->tcn_timer);
  91         cancel_delayed_work_sync(&br->gc_work);
  92 }
  93
  94 /* called under bridge lock */
  95 void br_stp_enable_port(struct net_bridge_port *p)
  96 {
  97         br_init_port(p);
  98         br_port_state_selection(p->br);
  99         br_ifinfo_notify(RTM_NEWLINK, p);
 100 }
 101
 102 /* called under bridge lock */
 103 void br_stp_disable_port(struct net_bridge_port *p)
 104 {
 105         struct net_bridge *br = p->br;
 106         int wasroot;
 107
 108         wasroot = br_is_root_bridge(br);
 109         br_become_designated_port(p);
 110         br_set_state(p, BR_STATE_DISABLED);
 111         p->topology_change_ack = 0;
 112         p->config_pending = 0;
 113
 114         br_ifinfo_notify(RTM_NEWLINK, p);
 115
 116         del_timer(&p->message_age_timer);
 117         del_timer(&p->forward_delay_timer);
 118         del_timer(&p->hold_timer);
 119
 120         br_fdb_delete_by_port(br, p, 0, 0);
 121         br_multicast_disable_port(p);
 122
 123         br_configuration_update(br);
 124
 125         br_port_state_selection(br);
 126
 127         if (br_is_root_bridge(br) && !wasroot)
 128                 br_become_root_bridge(br);
 129 }
 130
 131 static int br_stp_call_user(struct net_bridge *br, char *arg)
 132 {
 133         char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
 134         char *envp[] = { NULL };
 135         int rc;
 136
 137         /* call userspace STP and report program errors */
 138         rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 139         if (rc > 0) {
 140                 if (rc & 0xff)
 141                         br_debug(br, BR_STP_PROG " received signal %d\n",
 142                                  rc & 0x7f);
 143                 else
 144                         br_debug(br, BR_STP_PROG " exited with code %d\n",
 145                                  (rc >> 8) & 0xff);
 146         }
 147
 148         return rc;
 149 }
 150
 151 static void br_stp_start(struct net_bridge *br)
 152 {
 153         struct net_bridge_port *p;
 154         int err = -ENOENT;
 155
 156         if (net_eq(dev_net(br->dev), &init_net))
 157                 err = br_stp_call_user(br, "start");
 158
 159         if (err && err != -ENOENT)
 160                 br_err(br, "failed to start userspace STP (%d)\n", err);
 161
 162         spin_lock_bh(&br->lock);
 163
 164         if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
 165                 __br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
 166         else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
 167                 __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
 168
 169         if (!err) {
 170                 br->stp_enabled = BR_USER_STP;
 171                 br_debug(br, "userspace STP started\n");
 172
 173                 /* Stop hello and hold timers */
 174                 del_timer(&br->hello_timer);
 175                 list_for_each_entry(p, &br->port_list, list)
 176                         del_timer(&p->hold_timer);
 177         } else {
 178                 br->stp_enabled = BR_KERNEL_STP;
 179                 br_debug(br, "using kernel STP\n");
 180
 181                 /* To start timers on any ports left in blocking */
 182                 br_port_state_selection(br);
 183         }
 184
 185         spin_unlock_bh(&br->lock);
 186 }
 187
 188 static void br_stp_stop(struct net_bridge *br)
 189 {
 190         struct net_bridge_port *p;
 191         int err;
 192
 193         if (br->stp_enabled == BR_USER_STP) {
 194                 err = br_stp_call_user(br, "stop");
 195                 if (err)
 196                         br_err(br, "failed to stop userspace STP (%d)\n", err);
 197
 198                 /* To start timers on any ports left in blocking */
 199                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
 200                 list_for_each_entry(p, &br->port_list, list)
 201                         mod_timer(&p->hold_timer,
 202                                   round_jiffies(jiffies + BR_HOLD_TIME));
 203                 spin_lock_bh(&br->lock);
 204                 br_port_state_selection(br);
 205                 spin_unlock_bh(&br->lock);
 206         }
 207
 208         br->stp_enabled = BR_NO_STP;
 209 }
 210
 211 void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
 212 {
 213         ASSERT_RTNL();
 214
 215         if (val) {
 216                 if (br->stp_enabled == BR_NO_STP)
 217                         br_stp_start(br);
 218         } else {
 219                 if (br->stp_enabled != BR_NO_STP)
 220                         br_stp_stop(br);
 221         }
 222 }
 223
 224 /* called under bridge lock */
 225 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 226 {
 227         /* should be aligned on 2 bytes for ether_addr_equal() */
 228         unsigned short oldaddr_aligned[ETH_ALEN >> 1];
 229         unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
 230         struct net_bridge_port *p;
 231         int wasroot;
 232
 233         wasroot = br_is_root_bridge(br);
 234
 235         br_fdb_change_mac_address(br, addr);
 236
 237         memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
 238         memcpy(br->bridge_id.addr, addr, ETH_ALEN);
 239         memcpy(br->dev->dev_addr, addr, ETH_ALEN);
 240
 241         list_for_each_entry(p, &br->port_list, list) {
 242                 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
 243                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
 244
 245                 if (ether_addr_equal(p->designated_root.addr, oldaddr))
 246                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
 247         }
 248
 249         br_configuration_update(br);
 250         br_port_state_selection(br);
 251         if (br_is_root_bridge(br) && !wasroot)
 252                 br_become_root_bridge(br);
 253 }
 254
 255 /* should be aligned on 2 bytes for ether_addr_equal() */
 256 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
 257
 258 /* called under bridge lock */
 259 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
 260 {
 261         const unsigned char *br_mac_zero =
 262                         (const unsigned char *)br_mac_zero_aligned;
 263         const unsigned char *addr = br_mac_zero;
 264         struct net_bridge_port *p;
 265
 266         /* user has chosen a value so keep it */
 267         if (br->dev->addr_assign_type == NET_ADDR_SET)
 268                 return false;
 269
 270         list_for_each_entry(p, &br->port_list, list) {
 271                 if (addr == br_mac_zero ||
 272                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
 273                         addr = p->dev->dev_addr;
 274
 275         }
 276
 277         if (ether_addr_equal(br->bridge_id.addr, addr))
 278                 return false;   /* no change */
 279
 280         br_stp_change_bridge_id(br, addr);
 281         return true;
 282 }
 283
 284 /* Acquires and releases bridge lock */
 285 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
 286 {
 287         struct net_bridge_port *p;
 288         int wasroot;
 289
 290         spin_lock_bh(&br->lock);
 291         wasroot = br_is_root_bridge(br);
 292
 293         list_for_each_entry(p, &br->port_list, list) {
 294                 if (p->state != BR_STATE_DISABLED &&
 295                     br_is_designated_port(p)) {
 296                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
 297                         p->designated_bridge.prio[1] = newprio & 0xFF;
 298                 }
 299
 300         }
 301
 302         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
 303         br->bridge_id.prio[1] = newprio & 0xFF;
 304         br_configuration_update(br);
 305         br_port_state_selection(br);
 306         if (br_is_root_bridge(br) && !wasroot)
 307                 br_become_root_bridge(br);
 308         spin_unlock_bh(&br->lock);
 309 }
 310
 311 /* called under bridge lock */
 312 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 313 {
 314         port_id new_port_id;
 315
 316         if (newprio > BR_MAX_PORT_PRIORITY)
 317                 return -ERANGE;
 318
 319         new_port_id = br_make_port_id(newprio, p->port_no);
 320         if (br_is_designated_port(p))
 321                 p->designated_port = new_port_id;
 322
 323         p->port_id = new_port_id;
 324         p->priority = newprio;
 325         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
 326             p->port_id < p->designated_port) {
 327                 br_become_designated_port(p);
 328                 br_port_state_selection(p->br);
 329         }
 330
 331         return 0;
 332 }
 333
 334 /* called under bridge lock */
 335 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 336 {
 337         if (path_cost < BR_MIN_PATH_COST ||
 338             path_cost > BR_MAX_PATH_COST)
 339                 return -ERANGE;
 340
 341         p->flags |= BR_ADMIN_COST;
 342         p->path_cost = path_cost;
 343         br_configuration_update(p->br);
 344         br_port_state_selection(p->br);
 345         return 0;
 346 }
 347
 348 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 349 {
 350         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 351                id->prio[0], id->prio[1],
 352                id->addr[0], id->addr[1], id->addr[2],
 353                id->addr[3], id->addr[4], id->addr[5]);
 354 }