net/bridge/br_stp_if.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Spanning tree protocol; interface code
   4  *      Linux ethernet bridge
   5  *
   6  *      Authors:
   7  *      Lennert Buytenhek               <buytenh@gnu.org>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/kmod.h>
  12 #include <linux/etherdevice.h>
  13 #include <linux/rtnetlink.h>
  14 #include <net/switchdev.h>
  15
  16 #include "br_private.h"
  17 #include "br_private_stp.h"
  18
  19
  20 /* Port id is composed of priority and port number.
  21  * NB: some bits of priority are dropped to
  22  *     make room for more ports.
  23  */
  24 static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
  25 {
  26         return ((u16)priority << BR_PORT_BITS)
  27                 | (port_no & ((1<<BR_PORT_BITS)-1));
  28 }
  29
  30 #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
  31
  32 /* called under bridge lock */
  33 void br_init_port(struct net_bridge_port *p)
  34 {
  35         int err;
  36
  37         p->port_id = br_make_port_id(p->priority, p->port_no);
  38         br_become_designated_port(p);
  39         br_set_state(p, BR_STATE_BLOCKING);
  40         p->topology_change_ack = 0;
  41         p->config_pending = 0;
  42
  43         err = __set_ageing_time(p->dev, p->br->ageing_time);
  44         if (err)
  45                 netdev_err(p->dev, "failed to offload ageing time\n");
  46 }
  47
  48 /* NO locks held */
  49 void br_stp_enable_bridge(struct net_bridge *br)
  50 {
  51         struct net_bridge_port *p;
  52
  53         spin_lock_bh(&br->lock);
  54         if (br->stp_enabled == BR_KERNEL_STP)
  55                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
  56         mod_delayed_work(system_long_wq, &br->gc_work, HZ / 10);
  57
  58         br_config_bpdu_generation(br);
  59
  60         list_for_each_entry(p, &br->port_list, list) {
  61                 if (netif_running(p->dev) && netif_oper_up(p->dev))
  62                         br_stp_enable_port(p);
  63
  64         }
  65         spin_unlock_bh(&br->lock);
  66 }
  67
  68 /* NO locks held */
  69 void br_stp_disable_bridge(struct net_bridge *br)
  70 {
  71         struct net_bridge_port *p;
  72
  73         spin_lock_bh(&br->lock);
  74         list_for_each_entry(p, &br->port_list, list) {
  75                 if (p->state != BR_STATE_DISABLED)
  76                         br_stp_disable_port(p);
  77
  78         }
  79
  80         __br_set_topology_change(br, 0);
  81         br->topology_change_detected = 0;
  82         spin_unlock_bh(&br->lock);
  83
  84         del_timer_sync(&br->hello_timer);
  85         del_timer_sync(&br->topology_change_timer);
  86         del_timer_sync(&br->tcn_timer);
  87         cancel_delayed_work_sync(&br->gc_work);
  88 }
  89
  90 /* called under bridge lock */
  91 void br_stp_enable_port(struct net_bridge_port *p)
  92 {
  93         br_init_port(p);
  94         br_port_state_selection(p->br);
  95         br_ifinfo_notify(RTM_NEWLINK, NULL, p);
  96 }
  97
  98 /* called under bridge lock */
  99 void br_stp_disable_port(struct net_bridge_port *p)
 100 {
 101         struct net_bridge *br = p->br;
 102         int wasroot;
 103
 104         wasroot = br_is_root_bridge(br);
 105         br_become_designated_port(p);
 106         br_set_state(p, BR_STATE_DISABLED);
 107         p->topology_change_ack = 0;
 108         p->config_pending = 0;
 109
 110         br_ifinfo_notify(RTM_NEWLINK, NULL, p);
 111
 112         del_timer(&p->message_age_timer);
 113         del_timer(&p->forward_delay_timer);
 114         del_timer(&p->hold_timer);
 115
 116         if (!rcu_access_pointer(p->backup_port))
 117                 br_fdb_delete_by_port(br, p, 0, 0);
 118         br_multicast_disable_port(p);
 119
 120         br_configuration_update(br);
 121
 122         br_port_state_selection(br);
 123
 124         if (br_is_root_bridge(br) && !wasroot)
 125                 br_become_root_bridge(br);
 126 }
 127
 128 static int br_stp_call_user(struct net_bridge *br, char *arg)
 129 {
 130         char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
 131         char *envp[] = { NULL };
 132         int rc;
 133
 134         /* call userspace STP and report program errors */
 135         rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
 136         if (rc > 0) {
 137                 if (rc & 0xff)
 138                         br_debug(br, BR_STP_PROG " received signal %d\n",
 139                                  rc & 0x7f);
 140                 else
 141                         br_debug(br, BR_STP_PROG " exited with code %d\n",
 142                                  (rc >> 8) & 0xff);
 143         }
 144
 145         return rc;
 146 }
 147
 148 static void br_stp_start(struct net_bridge *br)
 149 {
 150         int err = -ENOENT;
 151
 152         if (net_eq(dev_net(br->dev), &init_net))
 153                 err = br_stp_call_user(br, "start");
 154
 155         if (err && err != -ENOENT)
 156                 br_err(br, "failed to start userspace STP (%d)\n", err);
 157
 158         spin_lock_bh(&br->lock);
 159
 160         if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
 161                 __br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
 162         else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
 163                 __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
 164
 165         if (!err) {
 166                 br->stp_enabled = BR_USER_STP;
 167                 br_debug(br, "userspace STP started\n");
 168         } else {
 169                 br->stp_enabled = BR_KERNEL_STP;
 170                 br_debug(br, "using kernel STP\n");
 171
 172                 /* To start timers on any ports left in blocking */
 173                 if (br->dev->flags & IFF_UP)
 174                         mod_timer(&br->hello_timer, jiffies + br->hello_time);
 175                 br_port_state_selection(br);
 176         }
 177
 178         spin_unlock_bh(&br->lock);
 179 }
 180
 181 static void br_stp_stop(struct net_bridge *br)
 182 {
 183         int err;
 184
 185         if (br->stp_enabled == BR_USER_STP) {
 186                 err = br_stp_call_user(br, "stop");
 187                 if (err)
 188                         br_err(br, "failed to stop userspace STP (%d)\n", err);
 189
 190                 /* To start timers on any ports left in blocking */
 191                 spin_lock_bh(&br->lock);
 192                 br_port_state_selection(br);
 193                 spin_unlock_bh(&br->lock);
 194         }
 195
 196         br->stp_enabled = BR_NO_STP;
 197 }
 198
 199 int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
 200                        struct netlink_ext_ack *extack)
 201 {
 202         ASSERT_RTNL();
 203
 204         if (br_mrp_enabled(br)) {
 205                 NL_SET_ERR_MSG_MOD(extack,
 206                                    "STP can't be enabled if MRP is already enabled");
 207                 return -EINVAL;
 208         }
 209
 210         if (val) {
 211                 if (br->stp_enabled == BR_NO_STP)
 212                         br_stp_start(br);
 213         } else {
 214                 if (br->stp_enabled != BR_NO_STP)
 215                         br_stp_stop(br);
 216         }
 217
 218         return 0;
 219 }
 220
 221 /* called under bridge lock */
 222 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
 223 {
 224         /* should be aligned on 2 bytes for ether_addr_equal() */
 225         unsigned short oldaddr_aligned[ETH_ALEN >> 1];
 226         unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
 227         struct net_bridge_port *p;
 228         int wasroot;
 229
 230         wasroot = br_is_root_bridge(br);
 231
 232         br_fdb_change_mac_address(br, addr);
 233
 234         memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
 235         memcpy(br->bridge_id.addr, addr, ETH_ALEN);
 236         memcpy(br->dev->dev_addr, addr, ETH_ALEN);
 237
 238         list_for_each_entry(p, &br->port_list, list) {
 239                 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
 240                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
 241
 242                 if (ether_addr_equal(p->designated_root.addr, oldaddr))
 243                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
 244         }
 245
 246         br_configuration_update(br);
 247         br_port_state_selection(br);
 248         if (br_is_root_bridge(br) && !wasroot)
 249                 br_become_root_bridge(br);
 250 }
 251
 252 /* should be aligned on 2 bytes for ether_addr_equal() */
 253 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
 254
 255 /* called under bridge lock */
 256 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
 257 {
 258         const unsigned char *br_mac_zero =
 259                         (const unsigned char *)br_mac_zero_aligned;
 260         const unsigned char *addr = br_mac_zero;
 261         struct net_bridge_port *p;
 262
 263         /* user has chosen a value so keep it */
 264         if (br->dev->addr_assign_type == NET_ADDR_SET)
 265                 return false;
 266
 267         list_for_each_entry(p, &br->port_list, list) {
 268                 if (addr == br_mac_zero ||
 269                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
 270                         addr = p->dev->dev_addr;
 271
 272         }
 273
 274         if (ether_addr_equal(br->bridge_id.addr, addr))
 275                 return false;   /* no change */
 276
 277         br_stp_change_bridge_id(br, addr);
 278         return true;
 279 }
 280
 281 /* Acquires and releases bridge lock */
 282 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
 283 {
 284         struct net_bridge_port *p;
 285         int wasroot;
 286
 287         spin_lock_bh(&br->lock);
 288         wasroot = br_is_root_bridge(br);
 289
 290         list_for_each_entry(p, &br->port_list, list) {
 291                 if (p->state != BR_STATE_DISABLED &&
 292                     br_is_designated_port(p)) {
 293                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
 294                         p->designated_bridge.prio[1] = newprio & 0xFF;
 295                 }
 296
 297         }
 298
 299         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
 300         br->bridge_id.prio[1] = newprio & 0xFF;
 301         br_configuration_update(br);
 302         br_port_state_selection(br);
 303         if (br_is_root_bridge(br) && !wasroot)
 304                 br_become_root_bridge(br);
 305         spin_unlock_bh(&br->lock);
 306 }
 307
 308 /* called under bridge lock */
 309 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
 310 {
 311         port_id new_port_id;
 312
 313         if (newprio > BR_MAX_PORT_PRIORITY)
 314                 return -ERANGE;
 315
 316         new_port_id = br_make_port_id(newprio, p->port_no);
 317         if (br_is_designated_port(p))
 318                 p->designated_port = new_port_id;
 319
 320         p->port_id = new_port_id;
 321         p->priority = newprio;
 322         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
 323             p->port_id < p->designated_port) {
 324                 br_become_designated_port(p);
 325                 br_port_state_selection(p->br);
 326         }
 327
 328         return 0;
 329 }
 330
 331 /* called under bridge lock */
 332 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
 333 {
 334         if (path_cost < BR_MIN_PATH_COST ||
 335             path_cost > BR_MAX_PATH_COST)
 336                 return -ERANGE;
 337
 338         p->flags |= BR_ADMIN_COST;
 339         p->path_cost = path_cost;
 340         br_configuration_update(p->br);
 341         br_port_state_selection(p->br);
 342         return 0;
 343 }
 344
 345 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
 346 {
 347         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
 348                id->prio[0], id->prio[1],
 349                id->addr[0], id->addr[1], id->addr[2],
 350                id->addr[3], id->addr[4], id->addr[5]);
 351 }