net/ax25/ax25_uid.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   5  */
   6
   7 #include <linux/capability.h>
   8 #include <linux/errno.h>
   9 #include <linux/types.h>
  10 #include <linux/socket.h>
  11 #include <linux/in.h>
  12 #include <linux/kernel.h>
  13 #include <linux/timer.h>
  14 #include <linux/string.h>
  15 #include <linux/sockios.h>
  16 #include <linux/net.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/slab.h>
  19 #include <net/ax25.h>
  20 #include <linux/inet.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/if_arp.h>
  23 #include <linux/skbuff.h>
  24 #include <net/sock.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/fcntl.h>
  27 #include <linux/mm.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/list.h>
  30 #include <linux/notifier.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/stat.h>
  34 #include <linux/sysctl.h>
  35 #include <linux/export.h>
  36 #include <net/ip.h>
  37 #include <net/arp.h>
  38
  39 /*
  40  *      Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
  41  */
  42
  43 static HLIST_HEAD(ax25_uid_list);
  44 static DEFINE_RWLOCK(ax25_uid_lock);
  45
  46 int ax25_uid_policy;
  47
  48 EXPORT_SYMBOL(ax25_uid_policy);
  49
  50 ax25_uid_assoc *ax25_findbyuid(kuid_t uid)
  51 {
  52         ax25_uid_assoc *ax25_uid, *res = NULL;
  53
  54         read_lock(&ax25_uid_lock);
  55         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  56                 if (uid_eq(ax25_uid->uid, uid)) {
  57                         ax25_uid_hold(ax25_uid);
  58                         res = ax25_uid;
  59                         break;
  60                 }
  61         }
  62         read_unlock(&ax25_uid_lock);
  63
  64         return res;
  65 }
  66
  67 EXPORT_SYMBOL(ax25_findbyuid);
  68
  69 int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
  70 {
  71         ax25_uid_assoc *ax25_uid;
  72         ax25_uid_assoc *user;
  73         unsigned long res;
  74
  75         switch (cmd) {
  76         case SIOCAX25GETUID:
  77                 res = -ENOENT;
  78                 read_lock(&ax25_uid_lock);
  79                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
  80                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
  81                                 res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
  82                                 break;
  83                         }
  84                 }
  85                 read_unlock(&ax25_uid_lock);
  86
  87                 return res;
  88
  89         case SIOCAX25ADDUID:
  90         {
  91                 kuid_t sax25_kuid;
  92                 if (!capable(CAP_NET_ADMIN))
  93                         return -EPERM;
  94                 sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
  95                 if (!uid_valid(sax25_kuid))
  96                         return -EINVAL;
  97                 user = ax25_findbyuid(sax25_kuid);
  98                 if (user) {
  99                         ax25_uid_put(user);
 100                         return -EEXIST;
 101                 }
 102                 if (sax->sax25_uid == 0)
 103                         return -EINVAL;
 104                 if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
 105                         return -ENOMEM;
 106
 107                 refcount_set(&ax25_uid->refcount, 1);
 108                 ax25_uid->uid  = sax25_kuid;
 109                 ax25_uid->call = sax->sax25_call;
 110
 111                 write_lock(&ax25_uid_lock);
 112                 hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
 113                 write_unlock(&ax25_uid_lock);
 114
 115                 return 0;
 116         }
 117         case SIOCAX25DELUID:
 118                 if (!capable(CAP_NET_ADMIN))
 119                         return -EPERM;
 120
 121                 ax25_uid = NULL;
 122                 write_lock(&ax25_uid_lock);
 123                 ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 124                         if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
 125                                 break;
 126                 }
 127                 if (ax25_uid == NULL) {
 128                         write_unlock(&ax25_uid_lock);
 129                         return -ENOENT;
 130                 }
 131                 hlist_del_init(&ax25_uid->uid_node);
 132                 ax25_uid_put(ax25_uid);
 133                 write_unlock(&ax25_uid_lock);
 134
 135                 return 0;
 136
 137         default:
 138                 return -EINVAL;
 139         }
 140
 141         return -EINVAL; /*NOTREACHED */
 142 }
 143
 144 #ifdef CONFIG_PROC_FS
 145
 146 static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
 147         __acquires(ax25_uid_lock)
 148 {
 149         read_lock(&ax25_uid_lock);
 150         return seq_hlist_start_head(&ax25_uid_list, *pos);
 151 }
 152
 153 static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 154 {
 155         return seq_hlist_next(v, &ax25_uid_list, pos);
 156 }
 157
 158 static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
 159         __releases(ax25_uid_lock)
 160 {
 161         read_unlock(&ax25_uid_lock);
 162 }
 163
 164 static int ax25_uid_seq_show(struct seq_file *seq, void *v)
 165 {
 166         char buf[11];
 167
 168         if (v == SEQ_START_TOKEN)
 169                 seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
 170         else {
 171                 struct ax25_uid_assoc *pt;
 172
 173                 pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
 174                 seq_printf(seq, "%6d %s\n",
 175                         from_kuid_munged(seq_user_ns(seq), pt->uid),
 176                         ax2asc(buf, &pt->call));
 177         }
 178         return 0;
 179 }
 180
 181 const struct seq_operations ax25_uid_seqops = {
 182         .start = ax25_uid_seq_start,
 183         .next = ax25_uid_seq_next,
 184         .stop = ax25_uid_seq_stop,
 185         .show = ax25_uid_seq_show,
 186 };
 187 #endif
 188
 189 /*
 190  *      Free all memory associated with UID/Callsign structures.
 191  */
 192 void __exit ax25_uid_free(void)
 193 {
 194         ax25_uid_assoc *ax25_uid;
 195
 196         write_lock(&ax25_uid_lock);
 197 again:
 198         ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
 199                 hlist_del_init(&ax25_uid->uid_node);
 200                 ax25_uid_put(ax25_uid);
 201                 goto again;
 202         }
 203         write_unlock(&ax25_uid_lock);
 204 }