drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2013-2018, The Linux Foundation. All rights reserved.
   3  *
   4  * RMNET configuration engine
   5  */
   6
   7 #include <net/sock.h>
   8 #include <linux/module.h>
   9 #include <linux/netlink.h>
  10 #include <linux/netdevice.h>
  11 #include "rmnet_config.h"
  12 #include "rmnet_handlers.h"
  13 #include "rmnet_vnd.h"
  14 #include "rmnet_private.h"
  15
  16 /* Locking scheme -
  17  * The shared resource which needs to be protected is realdev->rx_handler_data.
  18  * For the writer path, this is using rtnl_lock(). The writer paths are
  19  * rmnet_newlink(), rmnet_dellink() and rmnet_force_unassociate_device(). These
  20  * paths are already called with rtnl_lock() acquired in. There is also an
  21  * ASSERT_RTNL() to ensure that we are calling with rtnl acquired. For
  22  * dereference here, we will need to use rtnl_dereference(). Dev list writing
  23  * needs to happen with rtnl_lock() acquired for netdev_master_upper_dev_link().
  24  * For the reader path, the real_dev->rx_handler_data is called in the TX / RX
  25  * path. We only need rcu_read_lock() for these scenarios. In these cases,
  26  * the rcu_read_lock() is held in __dev_queue_xmit() and
  27  * netif_receive_skb_internal(), so readers need to use rcu_dereference_rtnl()
  28  * to get the relevant information. For dev list reading, we again acquire
  29  * rcu_read_lock() in rmnet_dellink() for netdev_master_upper_dev_get_rcu().
  30  * We also use unregister_netdevice_many() to free all rmnet devices in
  31  * rmnet_force_unassociate_device() so we dont lose the rtnl_lock() and free in
  32  * same context.
  33  */
  34
  35 /* Local Definitions and Declarations */
  36
  37 static const struct nla_policy rmnet_policy[IFLA_RMNET_MAX + 1] = {
  38         [IFLA_RMNET_MUX_ID]     = { .type = NLA_U16 },
  39         [IFLA_RMNET_FLAGS]      = { .len = sizeof(struct ifla_rmnet_flags) },
  40 };
  41
  42 static int rmnet_is_real_dev_registered(const struct net_device *real_dev)
  43 {
  44         return rcu_access_pointer(real_dev->rx_handler) == rmnet_rx_handler;
  45 }
  46
  47 /* Needs rtnl lock */
  48 static struct rmnet_port*
  49 rmnet_get_port_rtnl(const struct net_device *real_dev)
  50 {
  51         return rtnl_dereference(real_dev->rx_handler_data);
  52 }
  53
  54 static int rmnet_unregister_real_device(struct net_device *real_dev,
  55                                         struct rmnet_port *port)
  56 {
  57         if (port->nr_rmnet_devs)
  58                 return -EINVAL;
  59
  60         netdev_rx_handler_unregister(real_dev);
  61
  62         kfree(port);
  63
  64         /* release reference on real_dev */
  65         dev_put(real_dev);
  66
  67         netdev_dbg(real_dev, "Removed from rmnet\n");
  68         return 0;
  69 }
  70
  71 static int rmnet_register_real_device(struct net_device *real_dev)
  72 {
  73         struct rmnet_port *port;
  74         int rc, entry;
  75
  76         ASSERT_RTNL();
  77
  78         if (rmnet_is_real_dev_registered(real_dev))
  79                 return 0;
  80
  81         port = kzalloc(sizeof(*port), GFP_ATOMIC);
  82         if (!port)
  83                 return -ENOMEM;
  84
  85         port->dev = real_dev;
  86         rc = netdev_rx_handler_register(real_dev, rmnet_rx_handler, port);
  87         if (rc) {
  88                 kfree(port);
  89                 return -EBUSY;
  90         }
  91
  92         /* hold on to real dev for MAP data */
  93         dev_hold(real_dev);
  94
  95         for (entry = 0; entry < RMNET_MAX_LOGICAL_EP; entry++)
  96                 INIT_HLIST_HEAD(&port->muxed_ep[entry]);
  97
  98         netdev_dbg(real_dev, "registered with rmnet\n");
  99         return 0;
 100 }
 101
 102 static void rmnet_unregister_bridge(struct net_device *dev,
 103                                     struct rmnet_port *port)
 104 {
 105         struct rmnet_port *bridge_port;
 106         struct net_device *bridge_dev;
 107
 108         if (port->rmnet_mode != RMNET_EPMODE_BRIDGE)
 109                 return;
 110
 111         /* bridge slave handling */
 112         if (!port->nr_rmnet_devs) {
 113                 bridge_dev = port->bridge_ep;
 114
 115                 bridge_port = rmnet_get_port_rtnl(bridge_dev);
 116                 bridge_port->bridge_ep = NULL;
 117                 bridge_port->rmnet_mode = RMNET_EPMODE_VND;
 118         } else {
 119                 bridge_dev = port->bridge_ep;
 120
 121                 bridge_port = rmnet_get_port_rtnl(bridge_dev);
 122                 rmnet_unregister_real_device(bridge_dev, bridge_port);
 123         }
 124 }
 125
 126 static int rmnet_newlink(struct net *src_net, struct net_device *dev,
 127                          struct nlattr *tb[], struct nlattr *data[],
 128                          struct netlink_ext_ack *extack)
 129 {
 130         u32 data_format = RMNET_FLAGS_INGRESS_DEAGGREGATION;
 131         struct net_device *real_dev;
 132         int mode = RMNET_EPMODE_VND;
 133         struct rmnet_endpoint *ep;
 134         struct rmnet_port *port;
 135         int err = 0;
 136         u16 mux_id;
 137
 138         real_dev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
 139         if (!real_dev || !dev)
 140                 return -ENODEV;
 141
 142         if (!data[IFLA_RMNET_MUX_ID])
 143                 return -EINVAL;
 144
 145         ep = kzalloc(sizeof(*ep), GFP_ATOMIC);
 146         if (!ep)
 147                 return -ENOMEM;
 148
 149         mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
 150
 151         err = rmnet_register_real_device(real_dev);
 152         if (err)
 153                 goto err0;
 154
 155         port = rmnet_get_port_rtnl(real_dev);
 156         err = rmnet_vnd_newlink(mux_id, dev, port, real_dev, ep);
 157         if (err)
 158                 goto err1;
 159
 160         port->rmnet_mode = mode;
 161
 162         hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
 163
 164         if (data[IFLA_RMNET_FLAGS]) {
 165                 struct ifla_rmnet_flags *flags;
 166
 167                 flags = nla_data(data[IFLA_RMNET_FLAGS]);
 168                 data_format = flags->flags & flags->mask;
 169         }
 170
 171         netdev_dbg(dev, "data format [0x%08X]\n", data_format);
 172         port->data_format = data_format;
 173
 174         return 0;
 175
 176 err1:
 177         rmnet_unregister_real_device(real_dev, port);
 178 err0:
 179         kfree(ep);
 180         return err;
 181 }
 182
 183 static void rmnet_dellink(struct net_device *dev, struct list_head *head)
 184 {
 185         struct rmnet_priv *priv = netdev_priv(dev);
 186         struct net_device *real_dev;
 187         struct rmnet_endpoint *ep;
 188         struct rmnet_port *port;
 189         u8 mux_id;
 190
 191         real_dev = priv->real_dev;
 192
 193         if (!real_dev || !rmnet_is_real_dev_registered(real_dev))
 194                 return;
 195
 196         port = rmnet_get_port_rtnl(real_dev);
 197
 198         mux_id = rmnet_vnd_get_mux(dev);
 199
 200         ep = rmnet_get_endpoint(port, mux_id);
 201         if (ep) {
 202                 hlist_del_init_rcu(&ep->hlnode);
 203                 rmnet_unregister_bridge(dev, port);
 204                 rmnet_vnd_dellink(mux_id, port, ep);
 205                 kfree(ep);
 206         }
 207         rmnet_unregister_real_device(real_dev, port);
 208
 209         unregister_netdevice_queue(dev, head);
 210 }
 211
 212 static void rmnet_force_unassociate_device(struct net_device *dev)
 213 {
 214         struct net_device *real_dev = dev;
 215         struct hlist_node *tmp_ep;
 216         struct rmnet_endpoint *ep;
 217         struct rmnet_port *port;
 218         unsigned long bkt_ep;
 219         LIST_HEAD(list);
 220
 221         if (!rmnet_is_real_dev_registered(real_dev))
 222                 return;
 223
 224         ASSERT_RTNL();
 225
 226         port = rmnet_get_port_rtnl(dev);
 227
 228         rcu_read_lock();
 229         rmnet_unregister_bridge(dev, port);
 230
 231         hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) {
 232                 unregister_netdevice_queue(ep->egress_dev, &list);
 233                 rmnet_vnd_dellink(ep->mux_id, port, ep);
 234
 235                 hlist_del_init_rcu(&ep->hlnode);
 236                 kfree(ep);
 237         }
 238
 239         rcu_read_unlock();
 240         unregister_netdevice_many(&list);
 241
 242         rmnet_unregister_real_device(real_dev, port);
 243 }
 244
 245 static int rmnet_config_notify_cb(struct notifier_block *nb,
 246                                   unsigned long event, void *data)
 247 {
 248         struct net_device *dev = netdev_notifier_info_to_dev(data);
 249
 250         if (!dev)
 251                 return NOTIFY_DONE;
 252
 253         switch (event) {
 254         case NETDEV_UNREGISTER:
 255                 netdev_dbg(dev, "Kernel unregister\n");
 256                 rmnet_force_unassociate_device(dev);
 257                 break;
 258
 259         default:
 260                 break;
 261         }
 262
 263         return NOTIFY_DONE;
 264 }
 265
 266 static struct notifier_block rmnet_dev_notifier __read_mostly = {
 267         .notifier_call = rmnet_config_notify_cb,
 268 };
 269
 270 static int rmnet_rtnl_validate(struct nlattr *tb[], struct nlattr *data[],
 271                                struct netlink_ext_ack *extack)
 272 {
 273         u16 mux_id;
 274
 275         if (!data || !data[IFLA_RMNET_MUX_ID])
 276                 return -EINVAL;
 277
 278         mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
 279         if (mux_id > (RMNET_MAX_LOGICAL_EP - 1))
 280                 return -ERANGE;
 281
 282         return 0;
 283 }
 284
 285 static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
 286                             struct nlattr *data[],
 287                             struct netlink_ext_ack *extack)
 288 {
 289         struct rmnet_priv *priv = netdev_priv(dev);
 290         struct net_device *real_dev;
 291         struct rmnet_endpoint *ep;
 292         struct rmnet_port *port;
 293         u16 mux_id;
 294
 295         if (!dev)
 296                 return -ENODEV;
 297
 298         real_dev = __dev_get_by_index(dev_net(dev),
 299                                       nla_get_u32(tb[IFLA_LINK]));
 300
 301         if (!real_dev || !rmnet_is_real_dev_registered(real_dev))
 302                 return -ENODEV;
 303
 304         port = rmnet_get_port_rtnl(real_dev);
 305
 306         if (data[IFLA_RMNET_MUX_ID]) {
 307                 mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
 308                 ep = rmnet_get_endpoint(port, priv->mux_id);
 309                 if (!ep)
 310                         return -ENODEV;
 311
 312                 hlist_del_init_rcu(&ep->hlnode);
 313                 hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
 314
 315                 ep->mux_id = mux_id;
 316                 priv->mux_id = mux_id;
 317         }
 318
 319         if (data[IFLA_RMNET_FLAGS]) {
 320                 struct ifla_rmnet_flags *flags;
 321
 322                 flags = nla_data(data[IFLA_RMNET_FLAGS]);
 323                 port->data_format = flags->flags & flags->mask;
 324         }
 325
 326         return 0;
 327 }
 328
 329 static size_t rmnet_get_size(const struct net_device *dev)
 330 {
 331         return
 332                 /* IFLA_RMNET_MUX_ID */
 333                 nla_total_size(2) +
 334                 /* IFLA_RMNET_FLAGS */
 335                 nla_total_size(sizeof(struct ifla_rmnet_flags));
 336 }
 337
 338 static int rmnet_fill_info(struct sk_buff *skb, const struct net_device *dev)
 339 {
 340         struct rmnet_priv *priv = netdev_priv(dev);
 341         struct net_device *real_dev;
 342         struct ifla_rmnet_flags f;
 343         struct rmnet_port *port;
 344
 345         real_dev = priv->real_dev;
 346
 347         if (nla_put_u16(skb, IFLA_RMNET_MUX_ID, priv->mux_id))
 348                 goto nla_put_failure;
 349
 350         if (rmnet_is_real_dev_registered(real_dev)) {
 351                 port = rmnet_get_port_rtnl(real_dev);
 352                 f.flags = port->data_format;
 353         } else {
 354                 f.flags = 0;
 355         }
 356
 357         f.mask  = ~0;
 358
 359         if (nla_put(skb, IFLA_RMNET_FLAGS, sizeof(f), &f))
 360                 goto nla_put_failure;
 361
 362         return 0;
 363
 364 nla_put_failure:
 365         return -EMSGSIZE;
 366 }
 367
 368 struct rtnl_link_ops rmnet_link_ops __read_mostly = {
 369         .kind           = "rmnet",
 370         .maxtype        = __IFLA_RMNET_MAX,
 371         .priv_size      = sizeof(struct rmnet_priv),
 372         .setup          = rmnet_vnd_setup,
 373         .validate       = rmnet_rtnl_validate,
 374         .newlink        = rmnet_newlink,
 375         .dellink        = rmnet_dellink,
 376         .get_size       = rmnet_get_size,
 377         .changelink     = rmnet_changelink,
 378         .policy         = rmnet_policy,
 379         .fill_info      = rmnet_fill_info,
 380 };
 381
 382 /* Needs either rcu_read_lock() or rtnl lock */
 383 struct rmnet_port *rmnet_get_port(struct net_device *real_dev)
 384 {
 385         if (rmnet_is_real_dev_registered(real_dev))
 386                 return rcu_dereference_rtnl(real_dev->rx_handler_data);
 387         else
 388                 return NULL;
 389 }
 390
 391 struct rmnet_endpoint *rmnet_get_endpoint(struct rmnet_port *port, u8 mux_id)
 392 {
 393         struct rmnet_endpoint *ep;
 394
 395         hlist_for_each_entry_rcu(ep, &port->muxed_ep[mux_id], hlnode) {
 396                 if (ep->mux_id == mux_id)
 397                         return ep;
 398         }
 399
 400         return NULL;
 401 }
 402
 403 int rmnet_add_bridge(struct net_device *rmnet_dev,
 404                      struct net_device *slave_dev,
 405                      struct netlink_ext_ack *extack)
 406 {
 407         struct rmnet_priv *priv = netdev_priv(rmnet_dev);
 408         struct net_device *real_dev = priv->real_dev;
 409         struct rmnet_port *port, *slave_port;
 410         int err;
 411
 412         port = rmnet_get_port(real_dev);
 413
 414         /* If there is more than one rmnet dev attached, its probably being
 415          * used for muxing. Skip the briding in that case
 416          */
 417         if (port->nr_rmnet_devs > 1)
 418                 return -EINVAL;
 419
 420         if (rmnet_is_real_dev_registered(slave_dev))
 421                 return -EBUSY;
 422
 423         err = rmnet_register_real_device(slave_dev);
 424         if (err)
 425                 return -EBUSY;
 426
 427         slave_port = rmnet_get_port(slave_dev);
 428         slave_port->rmnet_mode = RMNET_EPMODE_BRIDGE;
 429         slave_port->bridge_ep = real_dev;
 430
 431         port->rmnet_mode = RMNET_EPMODE_BRIDGE;
 432         port->bridge_ep = slave_dev;
 433
 434         netdev_dbg(slave_dev, "registered with rmnet as slave\n");
 435         return 0;
 436 }
 437
 438 int rmnet_del_bridge(struct net_device *rmnet_dev,
 439                      struct net_device *slave_dev)
 440 {
 441         struct rmnet_priv *priv = netdev_priv(rmnet_dev);
 442         struct net_device *real_dev = priv->real_dev;
 443         struct rmnet_port *port, *slave_port;
 444
 445         port = rmnet_get_port(real_dev);
 446         port->rmnet_mode = RMNET_EPMODE_VND;
 447         port->bridge_ep = NULL;
 448
 449         slave_port = rmnet_get_port(slave_dev);
 450         rmnet_unregister_real_device(slave_dev, slave_port);
 451
 452         netdev_dbg(slave_dev, "removed from rmnet as slave\n");
 453         return 0;
 454 }
 455
 456 /* Startup/Shutdown */
 457
 458 static int __init rmnet_init(void)
 459 {
 460         int rc;
 461
 462         rc = register_netdevice_notifier(&rmnet_dev_notifier);
 463         if (rc != 0)
 464                 return rc;
 465
 466         rc = rtnl_link_register(&rmnet_link_ops);
 467         if (rc != 0) {
 468                 unregister_netdevice_notifier(&rmnet_dev_notifier);
 469                 return rc;
 470         }
 471         return rc;
 472 }
 473
 474 static void __exit rmnet_exit(void)
 475 {
 476         unregister_netdevice_notifier(&rmnet_dev_notifier);
 477         rtnl_link_unregister(&rmnet_link_ops);
 478 }
 479
 480 module_init(rmnet_init)
 481 module_exit(rmnet_exit)
 482 MODULE_LICENSE("GPL v2");