linux/net/phonet/pn_dev.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * File: pn_dev.c
   4 *
   5 * Phonet network device
   6 *
   7 * Copyright (C) 2008 Nokia Corporation.
   8 *
   9 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
  10 *          RĂ©mi Denis-Courmont
  11 */
  12
  13#include <linux/kernel.h>
  14#include <linux/net.h>
  15#include <linux/slab.h>
  16#include <linux/netdevice.h>
  17#include <linux/phonet.h>
  18#include <linux/proc_fs.h>
  19#include <linux/if_arp.h>
  20#include <net/sock.h>
  21#include <net/netns/generic.h>
  22#include <net/phonet/pn_dev.h>
  23
  24struct phonet_routes {
  25        struct mutex            lock;
  26        struct net_device __rcu *table[64];
  27};
  28
  29struct phonet_net {
  30        struct phonet_device_list pndevs;
  31        struct phonet_routes routes;
  32};
  33
  34static unsigned int phonet_net_id __read_mostly;
  35
  36static struct phonet_net *phonet_pernet(struct net *net)
  37{
  38        return net_generic(net, phonet_net_id);
  39}
  40
  41struct phonet_device_list *phonet_device_list(struct net *net)
  42{
  43        struct phonet_net *pnn = phonet_pernet(net);
  44        return &pnn->pndevs;
  45}
  46
  47/* Allocate new Phonet device. */
  48static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
  49{
  50        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  51        struct phonet_device *pnd = kmalloc(sizeof(*pnd), GFP_ATOMIC);
  52        if (pnd == NULL)
  53                return NULL;
  54        pnd->netdev = dev;
  55        bitmap_zero(pnd->addrs, 64);
  56
  57        BUG_ON(!mutex_is_locked(&pndevs->lock));
  58        list_add_rcu(&pnd->list, &pndevs->list);
  59        return pnd;
  60}
  61
  62static struct phonet_device *__phonet_get(struct net_device *dev)
  63{
  64        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  65        struct phonet_device *pnd;
  66
  67        BUG_ON(!mutex_is_locked(&pndevs->lock));
  68        list_for_each_entry(pnd, &pndevs->list, list) {
  69                if (pnd->netdev == dev)
  70                        return pnd;
  71        }
  72        return NULL;
  73}
  74
  75static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
  76{
  77        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  78        struct phonet_device *pnd;
  79
  80        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
  81                if (pnd->netdev == dev)
  82                        return pnd;
  83        }
  84        return NULL;
  85}
  86
  87static void phonet_device_destroy(struct net_device *dev)
  88{
  89        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  90        struct phonet_device *pnd;
  91
  92        ASSERT_RTNL();
  93
  94        mutex_lock(&pndevs->lock);
  95        pnd = __phonet_get(dev);
  96        if (pnd)
  97                list_del_rcu(&pnd->list);
  98        mutex_unlock(&pndevs->lock);
  99
 100        if (pnd) {
 101                u8 addr;
 102
 103                for_each_set_bit(addr, pnd->addrs, 64)
 104                        phonet_address_notify(RTM_DELADDR, dev, addr);
 105                kfree(pnd);
 106        }
 107}
 108
 109struct net_device *phonet_device_get(struct net *net)
 110{
 111        struct phonet_device_list *pndevs = phonet_device_list(net);
 112        struct phonet_device *pnd;
 113        struct net_device *dev = NULL;
 114
 115        rcu_read_lock();
 116        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
 117                dev = pnd->netdev;
 118                BUG_ON(!dev);
 119
 120                if ((dev->reg_state == NETREG_REGISTERED) &&
 121                        ((pnd->netdev->flags & IFF_UP)) == IFF_UP)
 122                        break;
 123                dev = NULL;
 124        }
 125        dev_hold(dev);
 126        rcu_read_unlock();
 127        return dev;
 128}
 129
 130int phonet_address_add(struct net_device *dev, u8 addr)
 131{
 132        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
 133        struct phonet_device *pnd;
 134        int err = 0;
 135
 136        mutex_lock(&pndevs->lock);
 137        /* Find or create Phonet-specific device data */
 138        pnd = __phonet_get(dev);
 139        if (pnd == NULL)
 140                pnd = __phonet_device_alloc(dev);
 141        if (unlikely(pnd == NULL))
 142                err = -ENOMEM;
 143        else if (test_and_set_bit(addr >> 2, pnd->addrs))
 144                err = -EEXIST;
 145        mutex_unlock(&pndevs->lock);
 146        return err;
 147}
 148
 149int phonet_address_del(struct net_device *dev, u8 addr)
 150{
 151        struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
 152        struct phonet_device *pnd;
 153        int err = 0;
 154
 155        mutex_lock(&pndevs->lock);
 156        pnd = __phonet_get(dev);
 157        if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
 158                err = -EADDRNOTAVAIL;
 159                pnd = NULL;
 160        } else if (bitmap_empty(pnd->addrs, 64))
 161                list_del_rcu(&pnd->list);
 162        else
 163                pnd = NULL;
 164        mutex_unlock(&pndevs->lock);
 165
 166        if (pnd)
 167                kfree_rcu(pnd, rcu);
 168
 169        return err;
 170}
 171
 172/* Gets a source address toward a destination, through a interface. */
 173u8 phonet_address_get(struct net_device *dev, u8 daddr)
 174{
 175        struct phonet_device *pnd;
 176        u8 saddr;
 177
 178        rcu_read_lock();
 179        pnd = __phonet_get_rcu(dev);
 180        if (pnd) {
 181                BUG_ON(bitmap_empty(pnd->addrs, 64));
 182
 183                /* Use same source address as destination, if possible */
 184                if (test_bit(daddr >> 2, pnd->addrs))
 185                        saddr = daddr;
 186                else
 187                        saddr = find_first_bit(pnd->addrs, 64) << 2;
 188        } else
 189                saddr = PN_NO_ADDR;
 190        rcu_read_unlock();
 191
 192        if (saddr == PN_NO_ADDR) {
 193                /* Fallback to another device */
 194                struct net_device *def_dev;
 195
 196                def_dev = phonet_device_get(dev_net(dev));
 197                if (def_dev) {
 198                        if (def_dev != dev)
 199                                saddr = phonet_address_get(def_dev, daddr);
 200                        dev_put(def_dev);
 201                }
 202        }
 203        return saddr;
 204}
 205
 206int phonet_address_lookup(struct net *net, u8 addr)
 207{
 208        struct phonet_device_list *pndevs = phonet_device_list(net);
 209        struct phonet_device *pnd;
 210        int err = -EADDRNOTAVAIL;
 211
 212        rcu_read_lock();
 213        list_for_each_entry_rcu(pnd, &pndevs->list, list) {
 214                /* Don't allow unregistering devices! */
 215                if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
 216                                ((pnd->netdev->flags & IFF_UP)) != IFF_UP)
 217                        continue;
 218
 219                if (test_bit(addr >> 2, pnd->addrs)) {
 220                        err = 0;
 221                        goto found;
 222                }
 223        }
 224found:
 225        rcu_read_unlock();
 226        return err;
 227}
 228
 229/* automatically configure a Phonet device, if supported */
 230static int phonet_device_autoconf(struct net_device *dev)
 231{
 232        struct if_phonet_req req;
 233        int ret;
 234
 235        if (!dev->netdev_ops->ndo_siocdevprivate)
 236                return -EOPNOTSUPP;
 237
 238        ret = dev->netdev_ops->ndo_siocdevprivate(dev, (struct ifreq *)&req,
 239                                                  NULL, SIOCPNGAUTOCONF);
 240        if (ret < 0)
 241                return ret;
 242
 243        ASSERT_RTNL();
 244        ret = phonet_address_add(dev, req.ifr_phonet_autoconf.device);
 245        if (ret)
 246                return ret;
 247        phonet_address_notify(RTM_NEWADDR, dev,
 248                                req.ifr_phonet_autoconf.device);
 249        return 0;
 250}
 251
 252static void phonet_route_autodel(struct net_device *dev)
 253{
 254        struct phonet_net *pnn = phonet_pernet(dev_net(dev));
 255        unsigned int i;
 256        DECLARE_BITMAP(deleted, 64);
 257
 258        /* Remove left-over Phonet routes */
 259        bitmap_zero(deleted, 64);
 260        mutex_lock(&pnn->routes.lock);
 261        for (i = 0; i < 64; i++)
 262                if (rcu_access_pointer(pnn->routes.table[i]) == dev) {
 263                        RCU_INIT_POINTER(pnn->routes.table[i], NULL);
 264                        set_bit(i, deleted);
 265                }
 266        mutex_unlock(&pnn->routes.lock);
 267
 268        if (bitmap_empty(deleted, 64))
 269                return; /* short-circuit RCU */
 270        synchronize_rcu();
 271        for_each_set_bit(i, deleted, 64) {
 272                rtm_phonet_notify(RTM_DELROUTE, dev, i);
 273                dev_put(dev);
 274        }
 275}
 276
 277/* notify Phonet of device events */
 278static int phonet_device_notify(struct notifier_block *me, unsigned long what,
 279                                void *ptr)
 280{
 281        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 282
 283        switch (what) {
 284        case NETDEV_REGISTER:
 285                if (dev->type == ARPHRD_PHONET)
 286                        phonet_device_autoconf(dev);
 287                break;
 288        case NETDEV_UNREGISTER:
 289                phonet_device_destroy(dev);
 290                phonet_route_autodel(dev);
 291                break;
 292        }
 293        return 0;
 294
 295}
 296
 297static struct notifier_block phonet_device_notifier = {
 298        .notifier_call = phonet_device_notify,
 299        .priority = 0,
 300};
 301
 302/* Per-namespace Phonet devices handling */
 303static int __net_init phonet_init_net(struct net *net)
 304{
 305        struct phonet_net *pnn = phonet_pernet(net);
 306
 307        if (!proc_create_net("phonet", 0, net->proc_net, &pn_sock_seq_ops,
 308                        sizeof(struct seq_net_private)))
 309                return -ENOMEM;
 310
 311        INIT_LIST_HEAD(&pnn->pndevs.list);
 312        mutex_init(&pnn->pndevs.lock);
 313        mutex_init(&pnn->routes.lock);
 314        return 0;
 315}
 316
 317static void __net_exit phonet_exit_net(struct net *net)
 318{
 319        struct phonet_net *pnn = phonet_pernet(net);
 320
 321        remove_proc_entry("phonet", net->proc_net);
 322        WARN_ON_ONCE(!list_empty(&pnn->pndevs.list));
 323}
 324
 325static struct pernet_operations phonet_net_ops = {
 326        .init = phonet_init_net,
 327        .exit = phonet_exit_net,
 328        .id   = &phonet_net_id,
 329        .size = sizeof(struct phonet_net),
 330};
 331
 332/* Initialize Phonet devices list */
 333int __init phonet_device_init(void)
 334{
 335        int err = register_pernet_subsys(&phonet_net_ops);
 336        if (err)
 337                return err;
 338
 339        proc_create_net("pnresource", 0, init_net.proc_net, &pn_res_seq_ops,
 340                        sizeof(struct seq_net_private));
 341        register_netdevice_notifier(&phonet_device_notifier);
 342        err = phonet_netlink_register();
 343        if (err)
 344                phonet_device_exit();
 345        return err;
 346}
 347
 348void phonet_device_exit(void)
 349{
 350        rtnl_unregister_all(PF_PHONET);
 351        unregister_netdevice_notifier(&phonet_device_notifier);
 352        unregister_pernet_subsys(&phonet_net_ops);
 353        remove_proc_entry("pnresource", init_net.proc_net);
 354}
 355
 356int phonet_route_add(struct net_device *dev, u8 daddr)
 357{
 358        struct phonet_net *pnn = phonet_pernet(dev_net(dev));
 359        struct phonet_routes *routes = &pnn->routes;
 360        int err = -EEXIST;
 361
 362        daddr = daddr >> 2;
 363        mutex_lock(&routes->lock);
 364        if (routes->table[daddr] == NULL) {
 365                rcu_assign_pointer(routes->table[daddr], dev);
 366                dev_hold(dev);
 367                err = 0;
 368        }
 369        mutex_unlock(&routes->lock);
 370        return err;
 371}
 372
 373int phonet_route_del(struct net_device *dev, u8 daddr)
 374{
 375        struct phonet_net *pnn = phonet_pernet(dev_net(dev));
 376        struct phonet_routes *routes = &pnn->routes;
 377
 378        daddr = daddr >> 2;
 379        mutex_lock(&routes->lock);
 380        if (rcu_access_pointer(routes->table[daddr]) == dev)
 381                RCU_INIT_POINTER(routes->table[daddr], NULL);
 382        else
 383                dev = NULL;
 384        mutex_unlock(&routes->lock);
 385
 386        if (!dev)
 387                return -ENOENT;
 388        synchronize_rcu();
 389        dev_put(dev);
 390        return 0;
 391}
 392
 393struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr)
 394{
 395        struct phonet_net *pnn = phonet_pernet(net);
 396        struct phonet_routes *routes = &pnn->routes;
 397        struct net_device *dev;
 398
 399        daddr >>= 2;
 400        dev = rcu_dereference(routes->table[daddr]);
 401        return dev;
 402}
 403
 404struct net_device *phonet_route_output(struct net *net, u8 daddr)
 405{
 406        struct phonet_net *pnn = phonet_pernet(net);
 407        struct phonet_routes *routes = &pnn->routes;
 408        struct net_device *dev;
 409
 410        daddr >>= 2;
 411        rcu_read_lock();
 412        dev = rcu_dereference(routes->table[daddr]);
 413        dev_hold(dev);
 414        rcu_read_unlock();
 415
 416        if (!dev)
 417                dev = phonet_device_get(net); /* Default route */
 418        return dev;
 419}
 420