text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *
   * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
   * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   * Copyright (C) Steven Whitehouse GW7RRM (stevew@acm.org)
   * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
   * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
   * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
   */
  
  #include <linux/capability.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/timer.h>
  #include <linux/in.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <linux/slab.h>
  #include <net/ax25.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/skbuff.h>
  #include <linux/spinlock.h>
  #include <net/sock.h>
  #include <linux/uaccess.h>
  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  #include <linux/init.h>
  #include <linux/seq_file.h>
  #include <linux/export.h>
  
  static ax25_route *ax25_route_list;
  DEFINE_RWLOCK(ax25_route_lock);
  
  void ax25_rt_device_down(struct net_device *dev)
  {
  	ax25_route *s, *t, *ax25_rt;
  
  	write_lock_bh(&ax25_route_lock);
  	ax25_rt = ax25_route_list;
  	while (ax25_rt != NULL) {
  		s       = ax25_rt;
  		ax25_rt = ax25_rt->next;
  
  		if (s->dev == dev) {
  			if (ax25_route_list == s) {
  				ax25_route_list = s->next;
  				kfree(s->digipeat);
  				kfree(s);
  			} else {
  				for (t = ax25_route_list; t != NULL; t = t->next) {
  					if (t->next == s) {
  						t->next = s->next;
  						kfree(s->digipeat);
  						kfree(s);
  						break;
  					}
  				}
  			}
  		}
  	}
  	write_unlock_bh(&ax25_route_lock);
  }
  
  static int __must_check ax25_rt_add(struct ax25_routes_struct *route)
  {
  	ax25_route *ax25_rt;
  	ax25_dev *ax25_dev;
  	int i;
  
  	if (route->digi_count > AX25_MAX_DIGIS)
  		return -EINVAL;
  
  	ax25_dev = ax25_addr_ax25dev(&route->port_addr);
  	if (!ax25_dev)
  		return -EINVAL;
  
  	write_lock_bh(&ax25_route_lock);
  
  	ax25_rt = ax25_route_list;
  	while (ax25_rt != NULL) {
  		if (ax25cmp(&ax25_rt->callsign, &route->dest_addr) == 0 &&
  			    ax25_rt->dev == ax25_dev->dev) {
  			kfree(ax25_rt->digipeat);
  			ax25_rt->digipeat = NULL;
  			if (route->digi_count != 0) {
  				if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
  					write_unlock_bh(&ax25_route_lock);
  					ax25_dev_put(ax25_dev);
  					return -ENOMEM;
  				}
  				ax25_rt->digipeat->lastrepeat = -1;
  				ax25_rt->digipeat->ndigi      = route->digi_count;
  				for (i = 0; i < route->digi_count; i++) {
  					ax25_rt->digipeat->repeated[i] = 0;
  					ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
  				}
  			}
  			write_unlock_bh(&ax25_route_lock);
  			ax25_dev_put(ax25_dev);
  			return 0;
  		}
  		ax25_rt = ax25_rt->next;
  	}
  
  	if ((ax25_rt = kmalloc(sizeof(ax25_route), GFP_ATOMIC)) == NULL) {
  		write_unlock_bh(&ax25_route_lock);
  		ax25_dev_put(ax25_dev);
  		return -ENOMEM;
  	}
  
  	ax25_rt->callsign     = route->dest_addr;
  	ax25_rt->dev          = ax25_dev->dev;
  	ax25_rt->digipeat     = NULL;
  	ax25_rt->ip_mode      = ' ';
  	if (route->digi_count != 0) {
  		if ((ax25_rt->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
  			write_unlock_bh(&ax25_route_lock);
  			kfree(ax25_rt);
  			ax25_dev_put(ax25_dev);
  			return -ENOMEM;
  		}
  		ax25_rt->digipeat->lastrepeat = -1;
  		ax25_rt->digipeat->ndigi      = route->digi_count;
  		for (i = 0; i < route->digi_count; i++) {
  			ax25_rt->digipeat->repeated[i] = 0;
  			ax25_rt->digipeat->calls[i]    = route->digi_addr[i];
  		}
  	}
  	ax25_rt->next   = ax25_route_list;
  	ax25_route_list = ax25_rt;
  	write_unlock_bh(&ax25_route_lock);
  	ax25_dev_put(ax25_dev);
  
  	return 0;
  }
  
  void __ax25_put_route(ax25_route *ax25_rt)
  {
  	kfree(ax25_rt->digipeat);
  	kfree(ax25_rt);
  }
  
  static int ax25_rt_del(struct ax25_routes_struct *route)
  {
  	ax25_route *s, *t, *ax25_rt;
  	ax25_dev *ax25_dev;
  
  	if ((ax25_dev = ax25_addr_ax25dev(&route->port_addr)) == NULL)
  		return -EINVAL;
  
  	write_lock_bh(&ax25_route_lock);
  
  	ax25_rt = ax25_route_list;
  	while (ax25_rt != NULL) {
  		s       = ax25_rt;
  		ax25_rt = ax25_rt->next;
  		if (s->dev == ax25_dev->dev &&
  		    ax25cmp(&route->dest_addr, &s->callsign) == 0) {
  			if (ax25_route_list == s) {
  				ax25_route_list = s->next;
  				__ax25_put_route(s);
  			} else {
  				for (t = ax25_route_list; t != NULL; t = t->next) {
  					if (t->next == s) {
  						t->next = s->next;
  						__ax25_put_route(s);
  						break;
  					}
  				}
  			}
  		}
  	}
  	write_unlock_bh(&ax25_route_lock);
  	ax25_dev_put(ax25_dev);
  
  	return 0;
  }
  
  static int ax25_rt_opt(struct ax25_route_opt_struct *rt_option)
  {
  	ax25_route *ax25_rt;
  	ax25_dev *ax25_dev;
  	int err = 0;
  
  	if ((ax25_dev = ax25_addr_ax25dev(&rt_option->port_addr)) == NULL)
  		return -EINVAL;
  
  	write_lock_bh(&ax25_route_lock);
  
  	ax25_rt = ax25_route_list;
  	while (ax25_rt != NULL) {
  		if (ax25_rt->dev == ax25_dev->dev &&
  		    ax25cmp(&rt_option->dest_addr, &ax25_rt->callsign) == 0) {
  			switch (rt_option->cmd) {
  			case AX25_SET_RT_IPMODE:
  				switch (rt_option->arg) {
  				case ' ':
  				case 'D':
  				case 'V':
  					ax25_rt->ip_mode = rt_option->arg;
  					break;
  				default:
  					err = -EINVAL;
  					goto out;
  				}
  				break;
  			default:
  				err = -EINVAL;
  				goto out;
  			}
  		}
  		ax25_rt = ax25_rt->next;
  	}
  
  out:
  	write_unlock_bh(&ax25_route_lock);
  	ax25_dev_put(ax25_dev);
  	return err;
  }
  
  int ax25_rt_ioctl(unsigned int cmd, void __user *arg)
  {
  	struct ax25_route_opt_struct rt_option;
  	struct ax25_routes_struct route;
  
  	switch (cmd) {
  	case SIOCADDRT:
  		if (copy_from_user(&route, arg, sizeof(route)))
  			return -EFAULT;
  		return ax25_rt_add(&route);
  
  	case SIOCDELRT:
  		if (copy_from_user(&route, arg, sizeof(route)))
  			return -EFAULT;
  		return ax25_rt_del(&route);
  
  	case SIOCAX25OPTRT:
  		if (copy_from_user(&rt_option, arg, sizeof(rt_option)))
  			return -EFAULT;
  		return ax25_rt_opt(&rt_option);
  
  	default:
  		return -EINVAL;
  	}
  }
  
  #ifdef CONFIG_PROC_FS
  
  static void *ax25_rt_seq_start(struct seq_file *seq, loff_t *pos)
  	__acquires(ax25_route_lock)
  {
  	struct ax25_route *ax25_rt;
  	int i = 1;
  
  	read_lock(&ax25_route_lock);
  	if (*pos == 0)
  		return SEQ_START_TOKEN;
  
  	for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
  		if (i == *pos)
  			return ax25_rt;
  		++i;
  	}
  
  	return NULL;
  }
  
  static void *ax25_rt_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	++*pos;
  	return (v == SEQ_START_TOKEN) ? ax25_route_list :
  		((struct ax25_route *) v)->next;
  }
  
  static void ax25_rt_seq_stop(struct seq_file *seq, void *v)
  	__releases(ax25_route_lock)
  {
  	read_unlock(&ax25_route_lock);
  }
  
  static int ax25_rt_seq_show(struct seq_file *seq, void *v)
  {
  	char buf[11];
  
  	if (v == SEQ_START_TOKEN)
  		seq_puts(seq, "callsign  dev  mode digipeaters\n");
  	else {
  		struct ax25_route *ax25_rt = v;
  		const char *callsign;
  		int i;
  
  		if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0)
  			callsign = "default";
  		else
  			callsign = ax2asc(buf, &ax25_rt->callsign);
  
  		seq_printf(seq, "%-9s %-4s",
  			callsign,
  			ax25_rt->dev ? ax25_rt->dev->name : "???");
  
  		switch (ax25_rt->ip_mode) {
  		case 'V':
  			seq_puts(seq, "   vc");
  			break;
  		case 'D':
  			seq_puts(seq, "   dg");
  			break;
  		default:
  			seq_puts(seq, "    *");
  			break;
  		}
  
  		if (ax25_rt->digipeat != NULL)
  			for (i = 0; i < ax25_rt->digipeat->ndigi; i++)
  				seq_printf(seq, " %s",
  				     ax2asc(buf, &ax25_rt->digipeat->calls[i]));
  
  		seq_puts(seq, "\n");
  	}
  	return 0;
  }
  
  const struct seq_operations ax25_rt_seqops = {
  	.start = ax25_rt_seq_start,
  	.next = ax25_rt_seq_next,
  	.stop = ax25_rt_seq_stop,
  	.show = ax25_rt_seq_show,
  };
  #endif
  
  /*
   *	Find AX.25 route
   *
   *	Only routes with a reference count of zero can be destroyed.
   *	Must be called with ax25_route_lock read locked.
   */
  ax25_route *ax25_get_route(ax25_address *addr, struct net_device *dev)
  {
  	ax25_route *ax25_spe_rt = NULL;
  	ax25_route *ax25_def_rt = NULL;
  	ax25_route *ax25_rt;
  
  	/*
  	 *	Bind to the physical interface we heard them on, or the default
  	 *	route if none is found;
  	 */
  	for (ax25_rt = ax25_route_list; ax25_rt != NULL; ax25_rt = ax25_rt->next) {
  		if (dev == NULL) {
  			if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev != NULL)
  				ax25_spe_rt = ax25_rt;
  			if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev != NULL)
  				ax25_def_rt = ax25_rt;
  		} else {
  			if (ax25cmp(&ax25_rt->callsign, addr) == 0 && ax25_rt->dev == dev)
  				ax25_spe_rt = ax25_rt;
  			if (ax25cmp(&ax25_rt->callsign, &null_ax25_address) == 0 && ax25_rt->dev == dev)
  				ax25_def_rt = ax25_rt;
  		}
  	}
  
  	ax25_rt = ax25_def_rt;
  	if (ax25_spe_rt != NULL)
  		ax25_rt = ax25_spe_rt;
  
  	return ax25_rt;
  }
  
  /*
   *	Adjust path: If you specify a default route and want to connect
   *      a target on the digipeater path but w/o having a special route
   *	set before, the path has to be truncated from your target on.
   */
  static inline void ax25_adjust_path(ax25_address *addr, ax25_digi *digipeat)
  {
  	int k;
  
  	for (k = 0; k < digipeat->ndigi; k++) {
  		if (ax25cmp(addr, &digipeat->calls[k]) == 0)
  			break;
  	}
  
  	digipeat->ndigi = k;
  }
  
  
  /*
   *	Find which interface to use.
   */
  int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
  {
  	ax25_uid_assoc *user;
  	ax25_route *ax25_rt;
  	int err = 0;
  
  	ax25_route_lock_use();
  	ax25_rt = ax25_get_route(addr, NULL);
  	if (!ax25_rt) {
  		ax25_route_lock_unuse();
  		return -EHOSTUNREACH;
  	}
  	if ((ax25->ax25_dev = ax25_dev_ax25dev(ax25_rt->dev)) == NULL) {
  		err = -EHOSTUNREACH;
  		goto put;
  	}
  
  	user = ax25_findbyuid(current_euid());
  	if (user) {
  		ax25->source_addr = user->call;
  		ax25_uid_put(user);
  	} else {
  		if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
  			err = -EPERM;
  			goto put;
  		}
  		ax25->source_addr = *(ax25_address *)ax25->ax25_dev->dev->dev_addr;
  	}
  
  	if (ax25_rt->digipeat != NULL) {
  		ax25->digipeat = kmemdup(ax25_rt->digipeat, sizeof(ax25_digi),
  					 GFP_ATOMIC);
  		if (ax25->digipeat == NULL) {
  			err = -ENOMEM;
  			goto put;
  		}
  		ax25_adjust_path(addr, ax25->digipeat);
  	}
  
  	if (ax25->sk != NULL) {
  		local_bh_disable();
  		bh_lock_sock(ax25->sk);
  		sock_reset_flag(ax25->sk, SOCK_ZAPPED);
  		bh_unlock_sock(ax25->sk);
  		local_bh_enable();
  	}
  
  put:
  	ax25_route_lock_unuse();
  	return err;
  }
  
  struct sk_buff *ax25_rt_build_path(struct sk_buff *skb, ax25_address *src,
  	ax25_address *dest, ax25_digi *digi)
  {
  	unsigned char *bp;
  	int len;
  
  	len = digi->ndigi * AX25_ADDR_LEN;
  
  	if (unlikely(skb_headroom(skb) < len)) {
  		skb = skb_expand_head(skb, len);
  		if (!skb) {
  			printk(KERN_CRIT "AX.25: ax25_dg_build_path - out of memory\n");
  			return NULL;
  		}
  	}
  
  	bp = skb_push(skb, len);
  
  	ax25_addr_build(bp, src, dest, digi, AX25_COMMAND, AX25_MODULUS);
  
  	return skb;
  }
  
  /*
   *	Free all memory associated with routing structures.
   */
  void __exit ax25_rt_free(void)
  {
  	ax25_route *s, *ax25_rt = ax25_route_list;
  
  	write_lock_bh(&ax25_route_lock);
  	while (ax25_rt != NULL) {
  		s       = ax25_rt;
  		ax25_rt = ax25_rt->next;
  
  		kfree(s->digipeat);
  		kfree(s);
  	}
  	write_unlock_bh(&ax25_route_lock);
  }
  