// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   *
   * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   */

  
  #include <linux/capability.h>

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>

  #include <linux/timer.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <linux/spinlock.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 <net/sock.h>

  #include <linux/uaccess.h>

  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>

  #include <linux/list.h>

  #include <linux/notifier.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/stat.h>

  #include <linux/sysctl.h>

  #include <linux/export.h>

  #include <net/ip.h>
  #include <net/arp.h>
  
  /*
   *	Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
   */

  static HLIST_HEAD(ax25_uid_list);

  static DEFINE_RWLOCK(ax25_uid_lock);

  int ax25_uid_policy;

  EXPORT_SYMBOL(ax25_uid_policy);

  ax25_uid_assoc *ax25_findbyuid(kuid_t uid)

  {

  	ax25_uid_assoc *ax25_uid, *res = NULL;

  
  	read_lock(&ax25_uid_lock);

  	ax25_uid_for_each(ax25_uid, &ax25_uid_list) {

  		if (uid_eq(ax25_uid->uid, uid)) {

  			ax25_uid_hold(ax25_uid);
  			res = ax25_uid;

  			break;
  		}
  	}
  	read_unlock(&ax25_uid_lock);

  	return res;

  }

  EXPORT_SYMBOL(ax25_findbyuid);

  int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
  {

  	ax25_uid_assoc *ax25_uid;

  	ax25_uid_assoc *user;

  	unsigned long res;
  
  	switch (cmd) {
  	case SIOCAX25GETUID:
  		res = -ENOENT;
  		read_lock(&ax25_uid_lock);

  		ax25_uid_for_each(ax25_uid, &ax25_uid_list) {

  			if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {

  				res = from_kuid_munged(current_user_ns(), ax25_uid->uid);

  				break;
  			}
  		}
  		read_unlock(&ax25_uid_lock);
  
  		return res;
  
  	case SIOCAX25ADDUID:

  	{
  		kuid_t sax25_kuid;

  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;

  		sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
  		if (!uid_valid(sax25_kuid))
  			return -EINVAL;
  		user = ax25_findbyuid(sax25_kuid);

  		if (user) {
  			ax25_uid_put(user);

  			return -EEXIST;

  		}

  		if (sax->sax25_uid == 0)
  			return -EINVAL;
  		if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
  			return -ENOMEM;

  		refcount_set(&ax25_uid->refcount, 1);

  		ax25_uid->uid  = sax25_kuid;

  		ax25_uid->call = sax->sax25_call;
  
  		write_lock(&ax25_uid_lock);

  		hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);

  		write_unlock(&ax25_uid_lock);
  
  		return 0;

  	}

  	case SIOCAX25DELUID:
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;

  		ax25_uid = NULL;

  		write_lock(&ax25_uid_lock);

  		ax25_uid_for_each(ax25_uid, &ax25_uid_list) {

  			if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)

  				break;

  		}
  		if (ax25_uid == NULL) {
  			write_unlock(&ax25_uid_lock);
  			return -ENOENT;
  		}

  		hlist_del_init(&ax25_uid->uid_node);
  		ax25_uid_put(ax25_uid);

  		write_unlock(&ax25_uid_lock);

  		return 0;

  
  	default:
  		return -EINVAL;
  	}
  
  	return -EINVAL;	/*NOTREACHED */
  }
  
  #ifdef CONFIG_PROC_FS
  
  static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)

  	__acquires(ax25_uid_lock)

  {

  	read_lock(&ax25_uid_lock);

  	return seq_hlist_start_head(&ax25_uid_list, *pos);

  }
  
  static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {

  	return seq_hlist_next(v, &ax25_uid_list, pos);

  }
  
  static void ax25_uid_seq_stop(struct seq_file *seq, void *v)

  	__releases(ax25_uid_lock)

  {
  	read_unlock(&ax25_uid_lock);
  }
  
  static int ax25_uid_seq_show(struct seq_file *seq, void *v)
  {

  	char buf[11];

  	if (v == SEQ_START_TOKEN)
  		seq_printf(seq, "Policy: %d
  ", ax25_uid_policy);
  	else {

  		struct ax25_uid_assoc *pt;

  		pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);

  		seq_printf(seq, "%6d %s
  ",
  			from_kuid_munged(seq_user_ns(seq), pt->uid),
  			ax2asc(buf, &pt->call));

  	}
  	return 0;
  }

  const struct seq_operations ax25_uid_seqops = {

  	.start = ax25_uid_seq_start,
  	.next = ax25_uid_seq_next,
  	.stop = ax25_uid_seq_stop,
  	.show = ax25_uid_seq_show,
  };

  #endif
  
  /*
   *	Free all memory associated with UID/Callsign structures.
   */
  void __exit ax25_uid_free(void)
  {

  	ax25_uid_assoc *ax25_uid;

  
  	write_lock(&ax25_uid_lock);

  again:

  	ax25_uid_for_each(ax25_uid, &ax25_uid_list) {

  		hlist_del_init(&ax25_uid->uid_node);
  		ax25_uid_put(ax25_uid);

  		goto again;

  	}

  	write_unlock(&ax25_uid_lock);
  }