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