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         struct hlist_node *node;
  58
  59         read_lock(&ax25_uid_lock);
  60         ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
  61                 if (uid_eq(ax25_uid->uid, uid)) {
  62                         ax25_uid_hold(ax25_uid);
  63                         res = ax25_uid;
  64                         break;
  65                 }
  66         }
  67         read_unlock(&ax25_uid_lock);
  68
  69         return res;
  70 }
  71
  72 EXPORT_SYMBOL(ax25_findbyuid);
  73
  74 int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
  75 {
  76         ax25_uid_assoc *ax25_uid;
  77         struct hlist_node *node;
  78         ax25_uid_assoc *user;
  79         unsigned long res;
  80
  81         switch (cmd) {
  82         case SIOCAX25GETUID:
  83                 res = -ENOENT;
  84                 read_lock(&ax25_uid_lock);
  85                 ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
  86                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
  87                                 res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
  88                                 break;
  89                         }
  90                 }
  91                 read_unlock(&ax25_uid_lock);
  92
  93                 return res;
  94
  95         case SIOCAX25ADDUID:
  96         {
  97                 kuid_t sax25_kuid;
  98                 if (!capable(CAP_NET_ADMIN))
  99                         return -EPERM;
 100                 sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
 101                 if (!uid_valid(sax25_kuid))
 102                         return -EINVAL;
 103                 user = ax25_findbyuid(sax25_kuid);
 104                 if (user) {
 105                         ax25_uid_put(user);
 106                         return -EEXIST;
 107                 }
 108                 if (sax->sax25_uid == 0)
 109                         return -EINVAL;
 110                 if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
 111                         return -ENOMEM;
 112
 113                 atomic_set(&ax25_uid->refcount, 1);
 114                 ax25_uid->uid  = sax25_kuid;
 115                 ax25_uid->call = sax->sax25_call;
 116
 117                 write_lock(&ax25_uid_lock);
 118                 hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
 119                 write_unlock(&ax25_uid_lock);
 120
 121                 return 0;
 122         }
 123         case SIOCAX25DELUID:
 124                 if (!capable(CAP_NET_ADMIN))
 125                         return -EPERM;
 126
 127                 ax25_uid = NULL;
 128                 write_lock(&ax25_uid_lock);
 129                 ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
 130                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
 131                                 break;
 132                 }
 133                 if (ax25_uid == NULL) {
 134                         write_unlock(&ax25_uid_lock);
 135                         return -ENOENT;
 136                 }
 137                 hlist_del_init(&ax25_uid->uid_node);
 138                 ax25_uid_put(ax25_uid);
 139                 write_unlock(&ax25_uid_lock);
 140
 141                 return 0;
 142
 143         default:
 144                 return -EINVAL;
 145         }
 146
 147         return -EINVAL; /*NOTREACHED */
 148 }
 149
 150 #ifdef CONFIG_PROC_FS
 151
 152 static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
 153         __acquires(ax25_uid_lock)
 154 {
 155         read_lock(&ax25_uid_lock);
 156         return seq_hlist_start_head(&ax25_uid_list, *pos);
 157 }
 158
 159 static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 160 {
 161         return seq_hlist_next(v, &ax25_uid_list, pos);
 162 }
 163
 164 static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
 165         __releases(ax25_uid_lock)
 166 {
 167         read_unlock(&ax25_uid_lock);
 168 }
 169
 170 static int ax25_uid_seq_show(struct seq_file *seq, void *v)
 171 {
 172         char buf[11];
 173
 174         if (v == SEQ_START_TOKEN)
 175                 seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
 176         else {
 177                 struct ax25_uid_assoc *pt;
 178
 179                 pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
 180                 seq_printf(seq, "%6d %s\n",
 181                         from_kuid_munged(seq_user_ns(seq), pt->uid),
 182                         ax2asc(buf, &pt->call));
 183         }
 184         return 0;
 185 }
 186
 187 static const struct seq_operations ax25_uid_seqops = {
 188         .start = ax25_uid_seq_start,
 189         .next = ax25_uid_seq_next,
 190         .stop = ax25_uid_seq_stop,
 191         .show = ax25_uid_seq_show,
 192 };
 193
 194 static int ax25_uid_info_open(struct inode *inode, struct file *file)
 195 {
 196         return seq_open(file, &ax25_uid_seqops);
 197 }
 198
 199 const struct file_operations ax25_uid_fops = {
 200         .owner = THIS_MODULE,
 201         .open = ax25_uid_info_open,
 202         .read = seq_read,
 203         .llseek = seq_lseek,
 204         .release = seq_release,
 205 };
 206
 207 #endif
 208
 209 /*
 210  *      Free all memory associated with UID/Callsign structures.
 211  */
 212 void __exit ax25_uid_free(void)
 213 {
 214         ax25_uid_assoc *ax25_uid;
 215         struct hlist_node *node;
 216
 217         write_lock(&ax25_uid_lock);
 218 again:
 219         ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
 220                 hlist_del_init(&ax25_uid->uid_node);
 221                 ax25_uid_put(ax25_uid);
 222                 goto again;
 223         }
 224         write_unlock(&ax25_uid_lock);
 225 }