linux/net/ax25/ax25_uid.c
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   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
  43static HLIST_HEAD(ax25_uid_list);
  44static DEFINE_RWLOCK(ax25_uid_lock);
  45
  46int ax25_uid_policy;
  47
  48EXPORT_SYMBOL(ax25_uid_policy);
  49
  50ax25_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
  67EXPORT_SYMBOL(ax25_findbyuid);
  68
  69int 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
 146static 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
 153static 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
 158static 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
 164static 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
 181const 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 */
 192void __exit ax25_uid_free(void)
 193{
 194        ax25_uid_assoc *ax25_uid;
 195
 196        write_lock(&ax25_uid_lock);
 197again:
 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}
 205