security/selinux/netif.c

   1 /*
   2  * Network interface table.
   3  *
   4  * Network interfaces (devices) do not have a security field, so we
   5  * maintain a table associating each interface with a SID.
   6  *
   7  * Author: James Morris <jmorris@redhat.com>
   8  *
   9  * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2,
  13  * as published by the Free Software Foundation.
  14  */
  15 #include <linux/init.h>
  16 #include <linux/types.h>
  17 #include <linux/stddef.h>
  18 #include <linux/kernel.h>
  19 #include <linux/list.h>
  20 #include <linux/notifier.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/rcupdate.h>
  23
  24 #include "security.h"
  25 #include "objsec.h"
  26 #include "netif.h"
  27
  28 #define SEL_NETIF_HASH_SIZE     64
  29 #define SEL_NETIF_HASH_MAX      1024
  30
  31 #undef DEBUG
  32
  33 #ifdef DEBUG
  34 #define DEBUGP printk
  35 #else
  36 #define DEBUGP(format, args...)
  37 #endif
  38
  39 static u32 sel_netif_total;
  40 static LIST_HEAD(sel_netif_list);
  41 static spinlock_t sel_netif_lock = SPIN_LOCK_UNLOCKED;
  42 static struct sel_netif sel_netif_hash[SEL_NETIF_HASH_SIZE];
  43
  44 static inline u32 sel_netif_hasfn(struct net_device *dev)
  45 {
  46         return (dev->ifindex & (SEL_NETIF_HASH_SIZE - 1));
  47 }
  48
  49 /*
  50  * All of the devices should normally fit in the hash, so we optimize
  51  * for that case.
  52  */
  53 static struct sel_netif *sel_netif_find(struct net_device *dev)
  54 {
  55         struct list_head *pos;
  56         int idx = sel_netif_hasfn(dev);
  57
  58         __list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
  59                 struct sel_netif *netif = list_entry(pos,
  60                                                      struct sel_netif, list);
  61                 if (likely(netif->nsec.dev == dev))
  62                         return netif;
  63         }
  64         return NULL;
  65 }
  66
  67 static int sel_netif_insert(struct sel_netif *netif)
  68 {
  69         int idx, ret = 0;
  70
  71         if (sel_netif_total >= SEL_NETIF_HASH_MAX) {
  72                 ret = -ENOSPC;
  73                 goto out;
  74         }
  75
  76         idx = sel_netif_hasfn(netif->nsec.dev);
  77         list_add_rcu(&netif->list, &sel_netif_hash[idx].list);
  78         atomic_set(&netif->users, 1);
  79         sel_netif_total++;
  80 out:
  81         return ret;
  82 }
  83
  84 struct sel_netif *sel_netif_lookup(struct net_device *dev)
  85 {
  86         int ret;
  87         struct sel_netif *netif, *new;
  88         struct netif_security_struct *nsec;
  89
  90         rcu_read_lock();
  91         netif = sel_netif_find(dev);
  92         rcu_read_unlock();
  93
  94         if (likely(netif != NULL))
  95                 goto out_hold;
  96
  97         new = kmalloc(sizeof(*new), GFP_ATOMIC);
  98         if (!new) {
  99                 netif = ERR_PTR(-ENOMEM);
 100                 goto out;
 101         }
 102
 103         memset(new, 0, sizeof(*new));
 104         nsec = &new->nsec;
 105
 106         ret = security_netif_sid(dev->name, &nsec->if_sid, &nsec->msg_sid);
 107         if (ret < 0) {
 108                 kfree(new);
 109                 netif = ERR_PTR(ret);
 110                 goto out;
 111         }
 112
 113         nsec->dev = dev;
 114
 115         spin_lock_bh(&sel_netif_lock);
 116
 117         netif = sel_netif_find(dev);
 118         if (netif) {
 119                 spin_unlock_bh(&sel_netif_lock);
 120                 kfree(new);
 121                 goto out_hold;
 122         }
 123
 124         sel_netif_insert(new);
 125         spin_unlock_bh(&sel_netif_lock);
 126
 127         netif = new;
 128
 129         DEBUGP("new: ifindex=%u name=%s if_sid=%u msg_sid=%u\n", dev->ifindex, dev->name,
 130                 nsec->if_sid, nsec->msg_sid);
 131 out_hold:
 132         atomic_inc(&netif->users);
 133 out:
 134         return netif;
 135 }
 136
 137 static void sel_netif_free(struct rcu_head *p)
 138 {
 139         struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
 140
 141         DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
 142         kfree(netif);
 143 }
 144
 145 static void sel_netif_destroy(struct sel_netif *netif)
 146 {
 147         DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
 148
 149         spin_lock_bh(&sel_netif_lock);
 150         list_del_rcu(&netif->list);
 151         sel_netif_total--;
 152         spin_unlock_bh(&sel_netif_lock);
 153
 154         call_rcu(&netif->rcu_head, sel_netif_free);
 155 }
 156
 157 void sel_netif_put(struct sel_netif *netif)
 158 {
 159         if (atomic_dec_and_test(&netif->users))
 160                 sel_netif_destroy(netif);
 161 }
 162
 163 static void sel_netif_kill(struct net_device *dev)
 164 {
 165         struct sel_netif *netif;
 166
 167         rcu_read_lock();
 168         netif = sel_netif_find(dev);
 169         rcu_read_unlock();
 170
 171         /* Drop internal reference */
 172         if (netif)
 173                 sel_netif_put(netif);
 174 }
 175
 176 static void sel_netif_flush(void)
 177 {
 178         int idx;
 179
 180         for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) {
 181                 struct list_head *pos;
 182
 183                 list_for_each_rcu(pos, &sel_netif_hash[idx].list) {
 184                         struct sel_netif *netif;
 185
 186                         netif = list_entry(pos, struct sel_netif, list);
 187                         if (netif)
 188                                 sel_netif_put(netif);
 189                 }
 190         }
 191 }
 192
 193 static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
 194                                   u16 class, u32 perms, u32 *retained)
 195 {
 196         if (event == AVC_CALLBACK_RESET) {
 197                 sel_netif_flush();
 198                 synchronize_net();
 199         }
 200         return 0;
 201 }
 202
 203 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
 204                                              unsigned long event, void *ptr)
 205 {
 206         struct net_device *dev = ptr;
 207
 208         if (event == NETDEV_DOWN)
 209                 sel_netif_kill(dev);
 210
 211         return NOTIFY_DONE;
 212 }
 213
 214 static struct notifier_block sel_netif_netdev_notifier = {
 215         .notifier_call = sel_netif_netdev_notifier_handler,
 216 };
 217
 218 static __init int sel_netif_init(void)
 219 {
 220         int i, err = 0;
 221
 222         if (!selinux_enabled)
 223                 goto out;
 224
 225         for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
 226                 INIT_LIST_HEAD(&sel_netif_hash[i].list);
 227
 228         register_netdevice_notifier(&sel_netif_netdev_notifier);
 229
 230         err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
 231                                SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
 232         if (err)
 233                 panic("avc_add_callback() failed, error %d\n", err);
 234
 235 out:
 236         return err;
 237 }
 238
 239 __initcall(sel_netif_init);
 240