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 <asm/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/netfilter.h>
  38 #include <linux/sysctl.h>
  39 #include <linux/export.h>
  40 #include <net/ip.h>
  41 #include <net/arp.h>
  42
  43 /*
  44  *      Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
  45  */
  46
  47 static HLIST_HEAD(ax25_uid_list);
  48 static DEFINE_RWLOCK(ax25_uid_lock);
  49
  50 int ax25_uid_policy;
  51
  52 EXPORT_SYMBOL(ax25_uid_policy);
  53
  54 ax25_uid_assoc *ax25_findbyuid(kuid_t uid)
  55 {
  56         ax25_uid_assoc *ax25_uid, *res = NULL;
  57
  58         read_lock(&ax25_uid_lock);
  59         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  60                 if (uid_eq(ax25_uid->uid, uid)) {
  61                         ax25_uid_hold(ax25_uid);
  62                         res = ax25_uid;
  63                         break;
  64                 }
  65         }
  66         read_unlock(&ax25_uid_lock);
  67
  68         return res;
  69 }
  70
  71 EXPORT_SYMBOL(ax25_findbyuid);
  72
  73 int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
  74 {
  75         ax25_uid_assoc *ax25_uid;
  76         ax25_uid_assoc *user;
  77         unsigned long res;
  78
  79         switch (cmd) {
  80         case SIOCAX25GETUID:
  81                 res = -ENOENT;
  82                 read_lock(&ax25_uid_lock);
  83                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  84                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
  85                                 res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
  86                                 break;
  87                         }
  88                 }
  89                 read_unlock(&ax25_uid_lock);
  90
  91                 return res;
  92
  93         case SIOCAX25ADDUID:
  94         {
  95                 kuid_t sax25_kuid;
  96                 if (!capable(CAP_NET_ADMIN))
  97                         return -EPERM;
  98                 sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
  99                 if (!uid_valid(sax25_kuid))
 100                         return -EINVAL;
 101                 user = ax25_findbyuid(sax25_kuid);
 102                 if (user) {
 103                         ax25_uid_put(user);
 104                         return -EEXIST;
 105                 }
 106                 if (sax->sax25_uid == 0)
 107                         return -EINVAL;
 108                 if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
 109                         return -ENOMEM;
 110
 111                 atomic_set(&ax25_uid->refcount, 1);
 112                 ax25_uid->uid  = sax25_kuid;
 113                 ax25_uid->call = sax->sax25_call;
 114
 115                 write_lock(&ax25_uid_lock);
 116                 hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
 117                 write_unlock(&ax25_uid_lock);
 118
 119                 return 0;
 120         }
 121         case SIOCAX25DELUID:
 122                 if (!capable(CAP_NET_ADMIN))
 123                         return -EPERM;
 124
 125                 ax25_uid = NULL;
 126                 write_lock(&ax25_uid_lock);
 127                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 128                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
 129                                 break;
 130                 }
 131                 if (ax25_uid == NULL) {
 132                         write_unlock(&ax25_uid_lock);
 133                         return -ENOENT;
 134                 }
 135                 hlist_del_init(&ax25_uid->uid_node);
 136                 ax25_uid_put(ax25_uid);
 137                 write_unlock(&ax25_uid_lock);
 138
 139                 return 0;
 140
 141         default:
 142                 return -EINVAL;
 143         }
 144
 145         return -EINVAL; /*NOTREACHED */
 146 }
 147
 148 #ifdef CONFIG_PROC_FS
 149
 150 static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
 151         __acquires(ax25_uid_lock)
 152 {
 153         read_lock(&ax25_uid_lock);
 154         return seq_hlist_start_head(&ax25_uid_list, *pos);
 155 }
 156
 157 static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 158 {
 159         return seq_hlist_next(v, &ax25_uid_list, pos);
 160 }
 161
 162 static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
 163         __releases(ax25_uid_lock)
 164 {
 165         read_unlock(&ax25_uid_lock);
 166 }
 167
 168 static int ax25_uid_seq_show(struct seq_file *seq, void *v)
 169 {
 170         char buf[11];
 171
 172         if (v == SEQ_START_TOKEN)
 173                 seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
 174         else {
 175                 struct ax25_uid_assoc *pt;
 176
 177                 pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
 178                 seq_printf(seq, "%6d %s\n",
 179                         from_kuid_munged(seq_user_ns(seq), pt->uid),
 180                         ax2asc(buf, &pt->call));
 181         }
 182         return 0;
 183 }
 184
 185 static const struct seq_operations ax25_uid_seqops = {
 186         .start = ax25_uid_seq_start,
 187         .next = ax25_uid_seq_next,
 188         .stop = ax25_uid_seq_stop,
 189         .show = ax25_uid_seq_show,
 190 };
 191
 192 static int ax25_uid_info_open(struct inode *inode, struct file *file)
 193 {
 194         return seq_open(file, &ax25_uid_seqops);
 195 }
 196
 197 const struct file_operations ax25_uid_fops = {
 198         .owner = THIS_MODULE,
 199         .open = ax25_uid_info_open,
 200         .read = seq_read,
 201         .llseek = seq_lseek,
 202         .release = seq_release,
 203 };
 204
 205 #endif
 206
 207 /*
 208  *      Free all memory associated with UID/Callsign structures.
 209  */
 210 void __exit ax25_uid_free(void)
 211 {
 212         ax25_uid_assoc *ax25_uid;
 213
 214         write_lock(&ax25_uid_lock);
 215 again:
 216         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 217                 hlist_del_init(&ax25_uid->uid_node);
 218                 ax25_uid_put(ax25_uid);
 219                 goto again;
 220         }
 221         write_unlock(&ax25_uid_lock);
 222 }