net/ax25/ax25_uid.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/errno.h>
  12 #include <linux/types.h>
  13 #include <linux/socket.h>
  14 #include <linux/in.h>
  15 #include <linux/kernel.h>
  16 #include <linux/timer.h>
  17 #include <linux/string.h>
  18 #include <linux/sockios.h>
  19 #include <linux/net.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/slab.h>
  22 #include <net/ax25.h>
  23 #include <linux/inet.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/if_arp.h>
  26 #include <linux/skbuff.h>
  27 #include <net/sock.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/mm.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/list.h>
  33 #include <linux/notifier.h>
  34 #include <linux/proc_fs.h>
  35 #include <linux/seq_file.h>
  36 #include <linux/stat.h>
  37 #include <linux/sysctl.h>
  38 #include <linux/export.h>
  39 #include <net/ip.h>
  40 #include <net/arp.h>
  41
  42 /*
  43  *      Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
  44  */
  45
  46 static HLIST_HEAD(ax25_uid_list);
  47 static DEFINE_RWLOCK(ax25_uid_lock);
  48
  49 int ax25_uid_policy;
  50
  51 EXPORT_SYMBOL(ax25_uid_policy);
  52
  53 ax25_uid_assoc *ax25_findbyuid(kuid_t uid)
  54 {
  55         ax25_uid_assoc *ax25_uid, *res = NULL;
  56
  57         read_lock(&ax25_uid_lock);
  58         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  59                 if (uid_eq(ax25_uid->uid, uid)) {
  60                         ax25_uid_hold(ax25_uid);
  61                         res = ax25_uid;
  62                         break;
  63                 }
  64         }
  65         read_unlock(&ax25_uid_lock);
  66
  67         return res;
  68 }
  69
  70 EXPORT_SYMBOL(ax25_findbyuid);
  71
  72 int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
  73 {
  74         ax25_uid_assoc *ax25_uid;
  75         ax25_uid_assoc *user;
  76         unsigned long res;
  77
  78         switch (cmd) {
  79         case SIOCAX25GETUID:
  80                 res = -ENOENT;
  81                 read_lock(&ax25_uid_lock);
  82                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  83                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
  84                                 res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
  85                                 break;
  86                         }
  87                 }
  88                 read_unlock(&ax25_uid_lock);
  89
  90                 return res;
  91
  92         case SIOCAX25ADDUID:
  93         {
  94                 kuid_t sax25_kuid;
  95                 if (!capable(CAP_NET_ADMIN))
  96                         return -EPERM;
  97                 sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
  98                 if (!uid_valid(sax25_kuid))
  99                         return -EINVAL;
 100                 user = ax25_findbyuid(sax25_kuid);
 101                 if (user) {
 102                         ax25_uid_put(user);
 103                         return -EEXIST;
 104                 }
 105                 if (sax->sax25_uid == 0)
 106                         return -EINVAL;
 107                 if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
 108                         return -ENOMEM;
 109
 110                 refcount_set(&ax25_uid->refcount, 1);
 111                 ax25_uid->uid  = sax25_kuid;
 112                 ax25_uid->call = sax->sax25_call;
 113
 114                 write_lock(&ax25_uid_lock);
 115                 hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
 116                 write_unlock(&ax25_uid_lock);
 117
 118                 return 0;
 119         }
 120         case SIOCAX25DELUID:
 121                 if (!capable(CAP_NET_ADMIN))
 122                         return -EPERM;
 123
 124                 ax25_uid = NULL;
 125                 write_lock(&ax25_uid_lock);
 126                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 127                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
 128                                 break;
 129                 }
 130                 if (ax25_uid == NULL) {
 131                         write_unlock(&ax25_uid_lock);
 132                         return -ENOENT;
 133                 }
 134                 hlist_del_init(&ax25_uid->uid_node);
 135                 ax25_uid_put(ax25_uid);
 136                 write_unlock(&ax25_uid_lock);
 137
 138                 return 0;
 139
 140         default:
 141                 return -EINVAL;
 142         }
 143
 144         return -EINVAL; /*NOTREACHED */
 145 }
 146
 147 #ifdef CONFIG_PROC_FS
 148
 149 static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
 150         __acquires(ax25_uid_lock)
 151 {
 152         read_lock(&ax25_uid_lock);
 153         return seq_hlist_start_head(&ax25_uid_list, *pos);
 154 }
 155
 156 static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 157 {
 158         return seq_hlist_next(v, &ax25_uid_list, pos);
 159 }
 160
 161 static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
 162         __releases(ax25_uid_lock)
 163 {
 164         read_unlock(&ax25_uid_lock);
 165 }
 166
 167 static int ax25_uid_seq_show(struct seq_file *seq, void *v)
 168 {
 169         char buf[11];
 170
 171         if (v == SEQ_START_TOKEN)
 172                 seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
 173         else {
 174                 struct ax25_uid_assoc *pt;
 175
 176                 pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
 177                 seq_printf(seq, "%6d %s\n",
 178                         from_kuid_munged(seq_user_ns(seq), pt->uid),
 179                         ax2asc(buf, &pt->call));
 180         }
 181         return 0;
 182 }
 183
 184 const struct seq_operations ax25_uid_seqops = {
 185         .start = ax25_uid_seq_start,
 186         .next = ax25_uid_seq_next,
 187         .stop = ax25_uid_seq_stop,
 188         .show = ax25_uid_seq_show,
 189 };
 190 #endif
 191
 192 /*
 193  *      Free all memory associated with UID/Callsign structures.
 194  */
 195 void __exit ax25_uid_free(void)
 196 {
 197         ax25_uid_assoc *ax25_uid;
 198
 199         write_lock(&ax25_uid_lock);
 200 again:
 201         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 202                 hlist_del_init(&ax25_uid->uid_node);
 203                 ax25_uid_put(ax25_uid);
 204                 goto again;
 205         }
 206         write_unlock(&ax25_uid_lock);
 207 }