text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * File: pn_dev.c
   *
   * Phonet network device
   *
   * Copyright (C) 2008 Nokia Corporation.
   *
   * Authors: Sakari Ailus <sakari.ailus@nokia.com>
   *          Rémi Denis-Courmont
   */
  
  #include <linux/kernel.h>
  #include <linux/net.h>
  #include <linux/slab.h>
  #include <linux/netdevice.h>
  #include <linux/phonet.h>
  #include <linux/proc_fs.h>
  #include <linux/if_arp.h>
  #include <net/sock.h>
  #include <net/netns/generic.h>
  #include <net/phonet/pn_dev.h>
  
  struct phonet_routes {
  	struct mutex		lock;
  	struct net_device __rcu	*table[64];
  };
  
  struct phonet_net {
  	struct phonet_device_list pndevs;
  	struct phonet_routes routes;
  };
  
  static unsigned int phonet_net_id __read_mostly;
  
  static struct phonet_net *phonet_pernet(struct net *net)
  {
  	return net_generic(net, phonet_net_id);
  }
  
  struct phonet_device_list *phonet_device_list(struct net *net)
  {
  	struct phonet_net *pnn = phonet_pernet(net);
  	return &pnn->pndevs;
  }
  
  /* Allocate new Phonet device. */
  static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd = kmalloc(sizeof(*pnd), GFP_ATOMIC);
  	if (pnd == NULL)
  		return NULL;
  	pnd->netdev = dev;
  	bitmap_zero(pnd->addrs, 64);
  
  	BUG_ON(!mutex_is_locked(&pndevs->lock));
  	list_add_rcu(&pnd->list, &pndevs->list);
  	return pnd;
  }
  
  static struct phonet_device *__phonet_get(struct net_device *dev)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd;
  
  	BUG_ON(!mutex_is_locked(&pndevs->lock));
  	list_for_each_entry(pnd, &pndevs->list, list) {
  		if (pnd->netdev == dev)
  			return pnd;
  	}
  	return NULL;
  }
  
  static struct phonet_device *__phonet_get_rcu(struct net_device *dev)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd;
  
  	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
  		if (pnd->netdev == dev)
  			return pnd;
  	}
  	return NULL;
  }
  
  static void phonet_device_destroy(struct net_device *dev)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd;
  
  	ASSERT_RTNL();
  
  	mutex_lock(&pndevs->lock);
  	pnd = __phonet_get(dev);
  	if (pnd)
  		list_del_rcu(&pnd->list);
  	mutex_unlock(&pndevs->lock);
  
  	if (pnd) {
  		u8 addr;
  
  		for_each_set_bit(addr, pnd->addrs, 64)
  			phonet_address_notify(RTM_DELADDR, dev, addr);
  		kfree(pnd);
  	}
  }
  
  struct net_device *phonet_device_get(struct net *net)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(net);
  	struct phonet_device *pnd;
  	struct net_device *dev = NULL;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
  		dev = pnd->netdev;
  		BUG_ON(!dev);
  
  		if ((dev->reg_state == NETREG_REGISTERED) &&
  			((pnd->netdev->flags & IFF_UP)) == IFF_UP)
  			break;
  		dev = NULL;
  	}
  	dev_hold(dev);
  	rcu_read_unlock();
  	return dev;
  }
  
  int phonet_address_add(struct net_device *dev, u8 addr)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd;
  	int err = 0;
  
  	mutex_lock(&pndevs->lock);
  	/* Find or create Phonet-specific device data */
  	pnd = __phonet_get(dev);
  	if (pnd == NULL)
  		pnd = __phonet_device_alloc(dev);
  	if (unlikely(pnd == NULL))
  		err = -ENOMEM;
  	else if (test_and_set_bit(addr >> 2, pnd->addrs))
  		err = -EEXIST;
  	mutex_unlock(&pndevs->lock);
  	return err;
  }
  
  int phonet_address_del(struct net_device *dev, u8 addr)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(dev_net(dev));
  	struct phonet_device *pnd;
  	int err = 0;
  
  	mutex_lock(&pndevs->lock);
  	pnd = __phonet_get(dev);
  	if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs)) {
  		err = -EADDRNOTAVAIL;
  		pnd = NULL;
  	} else if (bitmap_empty(pnd->addrs, 64))
  		list_del_rcu(&pnd->list);
  	else
  		pnd = NULL;
  	mutex_unlock(&pndevs->lock);
  
  	if (pnd)
  		kfree_rcu(pnd, rcu);
  
  	return err;
  }
  
  /* Gets a source address toward a destination, through a interface. */
  u8 phonet_address_get(struct net_device *dev, u8 daddr)
  {
  	struct phonet_device *pnd;
  	u8 saddr;
  
  	rcu_read_lock();
  	pnd = __phonet_get_rcu(dev);
  	if (pnd) {
  		BUG_ON(bitmap_empty(pnd->addrs, 64));
  
  		/* Use same source address as destination, if possible */
  		if (test_bit(daddr >> 2, pnd->addrs))
  			saddr = daddr;
  		else
  			saddr = find_first_bit(pnd->addrs, 64) << 2;
  	} else
  		saddr = PN_NO_ADDR;
  	rcu_read_unlock();
  
  	if (saddr == PN_NO_ADDR) {
  		/* Fallback to another device */
  		struct net_device *def_dev;
  
  		def_dev = phonet_device_get(dev_net(dev));
  		if (def_dev) {
  			if (def_dev != dev)
  				saddr = phonet_address_get(def_dev, daddr);
  			dev_put(def_dev);
  		}
  	}
  	return saddr;
  }
  
  int phonet_address_lookup(struct net *net, u8 addr)
  {
  	struct phonet_device_list *pndevs = phonet_device_list(net);
  	struct phonet_device *pnd;
  	int err = -EADDRNOTAVAIL;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(pnd, &pndevs->list, list) {
  		/* Don't allow unregistering devices! */
  		if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
  				((pnd->netdev->flags & IFF_UP)) != IFF_UP)
  			continue;
  
  		if (test_bit(addr >> 2, pnd->addrs)) {
  			err = 0;
  			goto found;
  		}
  	}
  found:
  	rcu_read_unlock();
  	return err;
  }
  
  /* automatically configure a Phonet device, if supported */
  static int phonet_device_autoconf(struct net_device *dev)
  {
  	struct if_phonet_req req;
  	int ret;
  
  	if (!dev->netdev_ops->ndo_siocdevprivate)
  		return -EOPNOTSUPP;
  
  	ret = dev->netdev_ops->ndo_siocdevprivate(dev, (struct ifreq *)&req,
  						  NULL, SIOCPNGAUTOCONF);
  	if (ret < 0)
  		return ret;
  
  	ASSERT_RTNL();
  	ret = phonet_address_add(dev, req.ifr_phonet_autoconf.device);
  	if (ret)
  		return ret;
  	phonet_address_notify(RTM_NEWADDR, dev,
  				req.ifr_phonet_autoconf.device);
  	return 0;
  }
  
  static void phonet_route_autodel(struct net_device *dev)
  {
  	struct phonet_net *pnn = phonet_pernet(dev_net(dev));
  	unsigned int i;
  	DECLARE_BITMAP(deleted, 64);
  
  	/* Remove left-over Phonet routes */
  	bitmap_zero(deleted, 64);
  	mutex_lock(&pnn->routes.lock);
  	for (i = 0; i < 64; i++)
  		if (rcu_access_pointer(pnn->routes.table[i]) == dev) {
  			RCU_INIT_POINTER(pnn->routes.table[i], NULL);
  			set_bit(i, deleted);
  		}
  	mutex_unlock(&pnn->routes.lock);
  
  	if (bitmap_empty(deleted, 64))
  		return; /* short-circuit RCU */
  	synchronize_rcu();
  	for_each_set_bit(i, deleted, 64) {
  		rtm_phonet_notify(RTM_DELROUTE, dev, i);
  		dev_put(dev);
  	}
  }
  
  /* notify Phonet of device events */
  static int phonet_device_notify(struct notifier_block *me, unsigned long what,
  				void *ptr)
  {
  	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  
  	switch (what) {
  	case NETDEV_REGISTER:
  		if (dev->type == ARPHRD_PHONET)
  			phonet_device_autoconf(dev);
  		break;
  	case NETDEV_UNREGISTER:
  		phonet_device_destroy(dev);
  		phonet_route_autodel(dev);
  		break;
  	}
  	return 0;
  
  }
  
  static struct notifier_block phonet_device_notifier = {
  	.notifier_call = phonet_device_notify,
  	.priority = 0,
  };
  
  /* Per-namespace Phonet devices handling */
  static int __net_init phonet_init_net(struct net *net)
  {
  	struct phonet_net *pnn = phonet_pernet(net);
  
  	if (!proc_create_net("phonet", 0, net->proc_net, &pn_sock_seq_ops,
  			sizeof(struct seq_net_private)))
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&pnn->pndevs.list);
  	mutex_init(&pnn->pndevs.lock);
  	mutex_init(&pnn->routes.lock);
  	return 0;
  }
  
  static void __net_exit phonet_exit_net(struct net *net)
  {
  	struct phonet_net *pnn = phonet_pernet(net);
  
  	remove_proc_entry("phonet", net->proc_net);
  	WARN_ON_ONCE(!list_empty(&pnn->pndevs.list));
  }
  
  static struct pernet_operations phonet_net_ops = {
  	.init = phonet_init_net,
  	.exit = phonet_exit_net,
  	.id   = &phonet_net_id,
  	.size = sizeof(struct phonet_net),
  };
  
  /* Initialize Phonet devices list */
  int __init phonet_device_init(void)
  {
  	int err = register_pernet_subsys(&phonet_net_ops);
  	if (err)
  		return err;
  
  	proc_create_net("pnresource", 0, init_net.proc_net, &pn_res_seq_ops,
  			sizeof(struct seq_net_private));
  	register_netdevice_notifier(&phonet_device_notifier);
  	err = phonet_netlink_register();
  	if (err)
  		phonet_device_exit();
  	return err;
  }
  
  void phonet_device_exit(void)
  {
  	rtnl_unregister_all(PF_PHONET);
  	unregister_netdevice_notifier(&phonet_device_notifier);
  	unregister_pernet_subsys(&phonet_net_ops);
  	remove_proc_entry("pnresource", init_net.proc_net);
  }
  
  int phonet_route_add(struct net_device *dev, u8 daddr)
  {
  	struct phonet_net *pnn = phonet_pernet(dev_net(dev));
  	struct phonet_routes *routes = &pnn->routes;
  	int err = -EEXIST;
  
  	daddr = daddr >> 2;
  	mutex_lock(&routes->lock);
  	if (routes->table[daddr] == NULL) {
  		rcu_assign_pointer(routes->table[daddr], dev);
  		dev_hold(dev);
  		err = 0;
  	}
  	mutex_unlock(&routes->lock);
  	return err;
  }
  
  int phonet_route_del(struct net_device *dev, u8 daddr)
  {
  	struct phonet_net *pnn = phonet_pernet(dev_net(dev));
  	struct phonet_routes *routes = &pnn->routes;
  
  	daddr = daddr >> 2;
  	mutex_lock(&routes->lock);
  	if (rcu_access_pointer(routes->table[daddr]) == dev)
  		RCU_INIT_POINTER(routes->table[daddr], NULL);
  	else
  		dev = NULL;
  	mutex_unlock(&routes->lock);
  
  	if (!dev)
  		return -ENOENT;
  	synchronize_rcu();
  	dev_put(dev);
  	return 0;
  }
  
  struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr)
  {
  	struct phonet_net *pnn = phonet_pernet(net);
  	struct phonet_routes *routes = &pnn->routes;
  	struct net_device *dev;
  
  	daddr >>= 2;
  	dev = rcu_dereference(routes->table[daddr]);
  	return dev;
  }
  
  struct net_device *phonet_route_output(struct net *net, u8 daddr)
  {
  	struct phonet_net *pnn = phonet_pernet(net);
  	struct phonet_routes *routes = &pnn->routes;
  	struct net_device *dev;
  
  	daddr >>= 2;
  	rcu_read_lock();
  	dev = rcu_dereference(routes->table[daddr]);
  	dev_hold(dev);
  	rcu_read_unlock();
  
  	if (!dev)
  		dev = phonet_device_get(net); /* Default route */
  	return dev;
  }
  