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
  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  */
  27 static 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 */
  36 void 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 */
  46 void 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 */
  65 void 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 */
  87 void 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 */
  96 void br_stp_disable_port(struct net_bridge_port *p)
  97 {
  98         struct net_bridge *br = p->br;
  99         int wasroot;
 100
 101         br_log_state(p);
 102
 103         wasroot = br_is_root_bridge(br);
 104         br_become_designated_port(p);
 105         p->state = BR_STATE_DISABLED;
 106         p->topology_change_ack = 0;
 107         p->config_pending = 0;
 108
 109         br_ifinfo_notify(RTM_NEWLINK, p);
 110
 111         del_timer(&p->message_age_timer);
 112         del_timer(&p->forward_delay_timer);
 113         del_timer(&p->hold_timer);
 114
 115         br_fdb_delete_by_port(br, p, 0);
 116         br_multicast_disable_port(p);
 117
 118         br_configuration_update(br);
 119
 120         br_port_state_selection(br);
 121
 122         if (br_is_root_bridge(br) && !wasroot)
 123                 br_become_root_bridge(br);
 124 }
 125
 126 static void br_stp_start(struct net_bridge *br)
 127 {
 128         int r;
 129         char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
 130         char *envp[] = { NULL };
 131
 132         if (net_eq(dev_net(br->dev), &init_net))
 133                 r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 134         else
 135                 r = -ENOENT;
 136         if (r == 0) {
 137                 br->stp_enabled = BR_USER_STP;
 138                 br_debug(br, "userspace STP started\n");
 139         } else {
 140                 br->stp_enabled = BR_KERNEL_STP;
 141                 br_debug(br, "using kernel STP\n");
 142
 143                 /* To start timers on any ports left in blocking */
 144                 spin_lock_bh(&br->lock);
 145                 br_port_state_selection(br);
 146                 spin_unlock_bh(&br->lock);
 147         }
 148 }
 149
 150 static void br_stp_stop(struct net_bridge *br)
 151 {
 152         int r;
 153         char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
 154         char *envp[] = { NULL };
 155
 156         if (br->stp_enabled == BR_USER_STP) {
 157                 r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 158                 br_info(br, "userspace STP stopped, return code %d\n", r);
 159
 160                 /* To start timers on any ports left in blocking */
 161                 spin_lock_bh(&br->lock);
 162                 br_port_state_selection(br);
 163                 spin_unlock_bh(&br->lock);
 164         }
 165
 166         br->stp_enabled = BR_NO_STP;
 167 }
 168
 169 void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
 170 {
 171         ASSERT_RTNL();
 172
 173         if (val) {
 174                 if (br->stp_enabled == BR_NO_STP)
 175                         br_stp_start(br);
 176         } else {
 177                 if (br->stp_enabled != BR_NO_STP)
 178                         br_stp_stop(br);
 179         }
 180 }
 181
 182 /* called under bridge lock */
 183 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 184 {
 185         /* should be aligned on 2 bytes for compare_ether_addr() */
 186         unsigned short oldaddr_aligned[ETH_ALEN >> 1];
 187         unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
 188         struct net_bridge_port *p;
 189         int wasroot;
 190
 191         wasroot = br_is_root_bridge(br);
 192
 193         memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
 194         memcpy(br->bridge_id.addr, addr, ETH_ALEN);
 195         memcpy(br->dev->dev_addr, addr, ETH_ALEN);
 196
 197         list_for_each_entry(p, &br->port_list, list) {
 198                 if (!compare_ether_addr(p->designated_bridge.addr, oldaddr))
 199                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
 200
 201                 if (!compare_ether_addr(p->designated_root.addr, oldaddr))
 202                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
 203
 204         }
 205
 206         br_configuration_update(br);
 207         br_port_state_selection(br);
 208         if (br_is_root_bridge(br) && !wasroot)
 209                 br_become_root_bridge(br);
 210 }
 211
 212 /* should be aligned on 2 bytes for compare_ether_addr() */
 213 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
 214
 215 /* called under bridge lock */
 216 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
 217 {
 218         const unsigned char *br_mac_zero =
 219                         (const unsigned char *)br_mac_zero_aligned;
 220         const unsigned char *addr = br_mac_zero;
 221         struct net_bridge_port *p;
 222
 223         /* user has chosen a value so keep it */
 224         if (br->flags & BR_SET_MAC_ADDR)
 225                 return false;
 226
 227         list_for_each_entry(p, &br->port_list, list) {
 228                 if (addr == br_mac_zero ||
 229                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
 230                         addr = p->dev->dev_addr;
 231
 232         }
 233
 234         if (compare_ether_addr(br->bridge_id.addr, addr) == 0)
 235                 return false;   /* no change */
 236
 237         br_stp_change_bridge_id(br, addr);
 238         return true;
 239 }
 240
 241 /* Acquires and releases bridge lock */
 242 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
 243 {
 244         struct net_bridge_port *p;
 245         int wasroot;
 246
 247         spin_lock_bh(&br->lock);
 248         wasroot = br_is_root_bridge(br);
 249
 250         list_for_each_entry(p, &br->port_list, list) {
 251                 if (p->state != BR_STATE_DISABLED &&
 252                     br_is_designated_port(p)) {
 253                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
 254                         p->designated_bridge.prio[1] = newprio & 0xFF;
 255                 }
 256
 257         }
 258
 259         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
 260         br->bridge_id.prio[1] = newprio & 0xFF;
 261         br_configuration_update(br);
 262         br_port_state_selection(br);
 263         if (br_is_root_bridge(br) && !wasroot)
 264                 br_become_root_bridge(br);
 265         spin_unlock_bh(&br->lock);
 266 }
 267
 268 /* called under bridge lock */
 269 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 270 {
 271         port_id new_port_id;
 272
 273         if (newprio > BR_MAX_PORT_PRIORITY)
 274                 return -ERANGE;
 275
 276         new_port_id = br_make_port_id(newprio, p->port_no);
 277         if (br_is_designated_port(p))
 278                 p->designated_port = new_port_id;
 279
 280         p->port_id = new_port_id;
 281         p->priority = newprio;
 282         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
 283             p->port_id < p->designated_port) {
 284                 br_become_designated_port(p);
 285                 br_port_state_selection(p->br);
 286         }
 287
 288         return 0;
 289 }
 290
 291 /* called under bridge lock */
 292 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 293 {
 294         if (path_cost < BR_MIN_PATH_COST ||
 295             path_cost > BR_MAX_PATH_COST)
 296                 return -ERANGE;
 297
 298         p->path_cost = path_cost;
 299         br_configuration_update(p->br);
 300         br_port_state_selection(p->br);
 301         return 0;
 302 }
 303
 304 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 305 {
 306         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 307                id->prio[0], id->prio[1],
 308                id->addr[0], id->addr[1], id->addr[2],
 309                id->addr[3], id->addr[4], id->addr[5]);
 310 }