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         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
 125 static 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
 146 static 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
 165 void 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 */
 179 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 180 {
 181         /* should be aligned on 2 bytes for compare_ether_addr() */
 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 (!compare_ether_addr(p->designated_bridge.addr, oldaddr))
 195                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
 196
 197                 if (!compare_ether_addr(p->designated_root.addr, oldaddr))
 198                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
 199
 200         }
 201
 202         br_configuration_update(br);
 203         br_port_state_selection(br);
 204         if (br_is_root_bridge(br) && !wasroot)
 205                 br_become_root_bridge(br);
 206 }
 207
 208 /* should be aligned on 2 bytes for compare_ether_addr() */
 209 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
 210
 211 /* called under bridge lock */
 212 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
 213 {
 214         const unsigned char *br_mac_zero =
 215                         (const unsigned char *)br_mac_zero_aligned;
 216         const unsigned char *addr = br_mac_zero;
 217         struct net_bridge_port *p;
 218
 219         /* user has chosen a value so keep it */
 220         if (br->flags & BR_SET_MAC_ADDR)
 221                 return false;
 222
 223         list_for_each_entry(p, &br->port_list, list) {
 224                 if (addr == br_mac_zero ||
 225                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
 226                         addr = p->dev->dev_addr;
 227
 228         }
 229
 230         if (compare_ether_addr(br->bridge_id.addr, addr) == 0)
 231                 return false;   /* no change */
 232
 233         br_stp_change_bridge_id(br, addr);
 234         return true;
 235 }
 236
 237 /* called under bridge lock */
 238 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
 239 {
 240         struct net_bridge_port *p;
 241         int wasroot;
 242
 243         wasroot = br_is_root_bridge(br);
 244
 245         list_for_each_entry(p, &br->port_list, list) {
 246                 if (p->state != BR_STATE_DISABLED &&
 247                     br_is_designated_port(p)) {
 248                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
 249                         p->designated_bridge.prio[1] = newprio & 0xFF;
 250                 }
 251
 252         }
 253
 254         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
 255         br->bridge_id.prio[1] = newprio & 0xFF;
 256         br_configuration_update(br);
 257         br_port_state_selection(br);
 258         if (br_is_root_bridge(br) && !wasroot)
 259                 br_become_root_bridge(br);
 260 }
 261
 262 /* called under bridge lock */
 263 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 264 {
 265         port_id new_port_id;
 266
 267         if (newprio > BR_MAX_PORT_PRIORITY)
 268                 return -ERANGE;
 269
 270         new_port_id = br_make_port_id(newprio, p->port_no);
 271         if (br_is_designated_port(p))
 272                 p->designated_port = new_port_id;
 273
 274         p->port_id = new_port_id;
 275         p->priority = newprio;
 276         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
 277             p->port_id < p->designated_port) {
 278                 br_become_designated_port(p);
 279                 br_port_state_selection(p->br);
 280         }
 281
 282         return 0;
 283 }
 284
 285 /* called under bridge lock */
 286 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 287 {
 288         if (path_cost < BR_MIN_PATH_COST ||
 289             path_cost > BR_MAX_PATH_COST)
 290                 return -ERANGE;
 291
 292         p->path_cost = path_cost;
 293         br_configuration_update(p->br);
 294         br_port_state_selection(p->br);
 295         return 0;
 296 }
 297
 298 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 299 {
 300         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 301                id->prio[0], id->prio[1],
 302                id->addr[0], id->addr[1], id->addr[2],
 303                id->addr[3], id->addr[4], id->addr[5]);
 304 }