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 eth_hw_addr_set(br->dev, addr); 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 } 352