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 #include <net/net_namespace.h>
  24
  25 #include "security.h"
  26 #include "objsec.h"
  27 #include "netif.h"
  28
  29 #define SEL_NETIF_HASH_SIZE     64
  30 #define SEL_NETIF_HASH_MAX      1024
  31
  32 #undef DEBUG
  33
  34 #ifdef DEBUG
  35 #define DEBUGP printk
  36 #else
  37 #define DEBUGP(format, args...)
  38 #endif
  39
  40 struct sel_netif
  41 {
  42         struct list_head list;
  43         struct netif_security_struct nsec;
  44         struct rcu_head rcu_head;
  45 };
  46
  47 static u32 sel_netif_total;
  48 static LIST_HEAD(sel_netif_list);
  49 static DEFINE_SPINLOCK(sel_netif_lock);
  50 static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
  51
  52 static inline u32 sel_netif_hasfn(struct net_device *dev)
  53 {
  54         return (dev->ifindex & (SEL_NETIF_HASH_SIZE - 1));
  55 }
  56
  57 /*
  58  * All of the devices should normally fit in the hash, so we optimize
  59  * for that case.
  60  */
  61 static inline struct sel_netif *sel_netif_find(struct net_device *dev)
  62 {
  63         struct list_head *pos;
  64         int idx = sel_netif_hasfn(dev);
  65
  66         __list_for_each_rcu(pos, &sel_netif_hash[idx]) {
  67                 struct sel_netif *netif = list_entry(pos,
  68                                                      struct sel_netif, list);
  69                 if (likely(netif->nsec.dev == dev))
  70                         return netif;
  71         }
  72         return NULL;
  73 }
  74
  75 static int sel_netif_insert(struct sel_netif *netif)
  76 {
  77         int idx, ret = 0;
  78
  79         if (sel_netif_total >= SEL_NETIF_HASH_MAX) {
  80                 ret = -ENOSPC;
  81                 goto out;
  82         }
  83
  84         idx = sel_netif_hasfn(netif->nsec.dev);
  85         list_add_rcu(&netif->list, &sel_netif_hash[idx]);
  86         sel_netif_total++;
  87 out:
  88         return ret;
  89 }
  90
  91 static void sel_netif_free(struct rcu_head *p)
  92 {
  93         struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head);
  94
  95         DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
  96         kfree(netif);
  97 }
  98
  99 static void sel_netif_destroy(struct sel_netif *netif)
 100 {
 101         DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name);
 102
 103         list_del_rcu(&netif->list);
 104         sel_netif_total--;
 105         call_rcu(&netif->rcu_head, sel_netif_free);
 106 }
 107
 108 static struct sel_netif *sel_netif_lookup(struct net_device *dev)
 109 {
 110         int ret;
 111         struct sel_netif *netif, *new;
 112         struct netif_security_struct *nsec;
 113
 114         netif = sel_netif_find(dev);
 115         if (likely(netif != NULL))
 116                 goto out;
 117
 118         new = kzalloc(sizeof(*new), GFP_ATOMIC);
 119         if (!new) {
 120                 netif = ERR_PTR(-ENOMEM);
 121                 goto out;
 122         }
 123
 124         nsec = &new->nsec;
 125
 126         ret = security_netif_sid(dev->name, &nsec->if_sid, &nsec->msg_sid);
 127         if (ret < 0) {
 128                 kfree(new);
 129                 netif = ERR_PTR(ret);
 130                 goto out;
 131         }
 132
 133         nsec->dev = dev;
 134
 135         spin_lock_bh(&sel_netif_lock);
 136
 137         netif = sel_netif_find(dev);
 138         if (netif) {
 139                 spin_unlock_bh(&sel_netif_lock);
 140                 kfree(new);
 141                 goto out;
 142         }
 143
 144         ret = sel_netif_insert(new);
 145         spin_unlock_bh(&sel_netif_lock);
 146
 147         if (ret) {
 148                 kfree(new);
 149                 netif = ERR_PTR(ret);
 150                 goto out;
 151         }
 152
 153         netif = new;
 154
 155         DEBUGP("new: ifindex=%u name=%s if_sid=%u msg_sid=%u\n", dev->ifindex, dev->name,
 156                 nsec->if_sid, nsec->msg_sid);
 157 out:
 158         return netif;
 159 }
 160
 161 static void sel_netif_assign_sids(u32 if_sid_in, u32 msg_sid_in, u32 *if_sid_out, u32 *msg_sid_out)
 162 {
 163         if (if_sid_out)
 164                 *if_sid_out = if_sid_in;
 165         if (msg_sid_out)
 166                 *msg_sid_out = msg_sid_in;
 167 }
 168
 169 static int sel_netif_sids_slow(struct net_device *dev, u32 *if_sid, u32 *msg_sid)
 170 {
 171         int ret = 0;
 172         u32 tmp_if_sid, tmp_msg_sid;
 173
 174         ret = security_netif_sid(dev->name, &tmp_if_sid, &tmp_msg_sid);
 175         if (!ret)
 176                 sel_netif_assign_sids(tmp_if_sid, tmp_msg_sid, if_sid, msg_sid);
 177         return ret;
 178 }
 179
 180 int sel_netif_sids(struct net_device *dev, u32 *if_sid, u32 *msg_sid)
 181 {
 182         int ret = 0;
 183         struct sel_netif *netif;
 184
 185         rcu_read_lock();
 186         netif = sel_netif_lookup(dev);
 187         if (IS_ERR(netif)) {
 188                 rcu_read_unlock();
 189                 ret = sel_netif_sids_slow(dev, if_sid, msg_sid);
 190                 goto out;
 191         }
 192         sel_netif_assign_sids(netif->nsec.if_sid, netif->nsec.msg_sid, if_sid, msg_sid);
 193         rcu_read_unlock();
 194 out:
 195         return ret;
 196 }
 197
 198 static void sel_netif_kill(struct net_device *dev)
 199 {
 200         struct sel_netif *netif;
 201
 202         spin_lock_bh(&sel_netif_lock);
 203         netif = sel_netif_find(dev);
 204         if (netif)
 205                 sel_netif_destroy(netif);
 206         spin_unlock_bh(&sel_netif_lock);
 207 }
 208
 209 static void sel_netif_flush(void)
 210 {
 211         int idx;
 212
 213         spin_lock_bh(&sel_netif_lock);
 214         for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) {
 215                 struct sel_netif *netif;
 216
 217                 list_for_each_entry(netif, &sel_netif_hash[idx], list)
 218                         sel_netif_destroy(netif);
 219         }
 220         spin_unlock_bh(&sel_netif_lock);
 221 }
 222
 223 static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid,
 224                                   u16 class, u32 perms, u32 *retained)
 225 {
 226         if (event == AVC_CALLBACK_RESET) {
 227                 sel_netif_flush();
 228                 synchronize_net();
 229         }
 230         return 0;
 231 }
 232
 233 static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
 234                                              unsigned long event, void *ptr)
 235 {
 236         struct net_device *dev = ptr;
 237
 238         if (dev->nd_net != &init_net)
 239                 return NOTIFY_DONE;
 240
 241         if (event == NETDEV_DOWN)
 242                 sel_netif_kill(dev);
 243
 244         return NOTIFY_DONE;
 245 }
 246
 247 static struct notifier_block sel_netif_netdev_notifier = {
 248         .notifier_call = sel_netif_netdev_notifier_handler,
 249 };
 250
 251 static __init int sel_netif_init(void)
 252 {
 253         int i, err = 0;
 254
 255         if (!selinux_enabled)
 256                 goto out;
 257
 258         for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
 259                 INIT_LIST_HEAD(&sel_netif_hash[i]);
 260
 261         register_netdevice_notifier(&sel_netif_netdev_notifier);
 262
 263         err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET,
 264                                SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
 265         if (err)
 266                 panic("avc_add_callback() failed, error %d\n", err);
 267
 268 out:
 269         return err;
 270 }
 271
 272 __initcall(sel_netif_init);
 273