security/selinux/netlabel.c

   1 /*
   2  * SELinux NetLabel Support
   3  *
   4  * This file provides the necessary glue to tie NetLabel into the SELinux
   5  * subsystem.
   6  *
   7  * Author: Paul Moore <paul.moore@hp.com>
   8  *
   9  */
  10
  11 /*
  12  * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
  13  *
  14  * This program is free software;  you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  22  * the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program;  if not, write to the Free Software
  26  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  27  *
  28  */
  29
  30 #include <linux/spinlock.h>
  31 #include <linux/rcupdate.h>
  32 #include <net/sock.h>
  33 #include <net/netlabel.h>
  34
  35 #include "objsec.h"
  36 #include "security.h"
  37
  38 /**
  39  * selinux_netlbl_sock_setsid - Label a socket using the NetLabel mechanism
  40  * @sk: the socket to label
  41  * @sid: the SID to use
  42  *
  43  * Description:
  44  * Attempt to label a socket using the NetLabel mechanism using the given
  45  * SID.  Returns zero values on success, negative values on failure.  The
  46  * caller is responsibile for calling rcu_read_lock() before calling this
  47  * this function and rcu_read_unlock() after this function returns.
  48  *
  49  */
  50 static int selinux_netlbl_sock_setsid(struct sock *sk, u32 sid)
  51 {
  52         int rc;
  53         struct sk_security_struct *sksec = sk->sk_security;
  54         struct netlbl_lsm_secattr secattr;
  55
  56         rc = security_netlbl_sid_to_secattr(sid, &secattr);
  57         if (rc != 0)
  58                 return rc;
  59
  60         rc = netlbl_sock_setattr(sk, &secattr);
  61         if (rc == 0) {
  62                 spin_lock_bh(&sksec->nlbl_lock);
  63                 sksec->nlbl_state = NLBL_LABELED;
  64                 spin_unlock_bh(&sksec->nlbl_lock);
  65         }
  66
  67         return rc;
  68 }
  69
  70 /**
  71  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
  72  *
  73  * Description:
  74  * Invalidate the NetLabel security attribute mapping cache.
  75  *
  76  */
  77 void selinux_netlbl_cache_invalidate(void)
  78 {
  79         netlbl_cache_invalidate();
  80 }
  81
  82 /**
  83  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
  84  * @ssec: the sk_security_struct
  85  * @family: the socket family
  86  *
  87  * Description:
  88  * Called when the NetLabel state of a sk_security_struct needs to be reset.
  89  * The caller is responsibile for all the NetLabel sk_security_struct locking.
  90  *
  91  */
  92 void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
  93                                       int family)
  94 {
  95         if (family == PF_INET)
  96                 ssec->nlbl_state = NLBL_REQUIRE;
  97         else
  98                 ssec->nlbl_state = NLBL_UNSET;
  99 }
 100
 101 /**
 102  * selinux_netlbl_sk_security_init - Setup the NetLabel fields
 103  * @ssec: the sk_security_struct
 104  * @family: the socket family
 105  *
 106  * Description:
 107  * Called when a new sk_security_struct is allocated to initialize the NetLabel
 108  * fields.
 109  *
 110  */
 111 void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
 112                                      int family)
 113 {
 114         /* No locking needed, we are the only one who has access to ssec */
 115         selinux_netlbl_sk_security_reset(ssec, family);
 116         spin_lock_init(&ssec->nlbl_lock);
 117 }
 118
 119 /**
 120  * selinux_netlbl_sk_security_clone - Copy the NetLabel fields
 121  * @ssec: the original sk_security_struct
 122  * @newssec: the cloned sk_security_struct
 123  *
 124  * Description:
 125  * Clone the NetLabel specific sk_security_struct fields from @ssec to
 126  * @newssec.
 127  *
 128  */
 129 void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
 130                                       struct sk_security_struct *newssec)
 131 {
 132         /* We don't need to take newssec->nlbl_lock because we are the only
 133          * thread with access to newssec, but we do need to take the RCU read
 134          * lock as other threads could have access to ssec */
 135         rcu_read_lock();
 136         selinux_netlbl_sk_security_reset(newssec, ssec->sk->sk_family);
 137         newssec->sclass = ssec->sclass;
 138         rcu_read_unlock();
 139 }
 140
 141 /**
 142  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 143  * @skb: the packet
 144  * @base_sid: the SELinux SID to use as a context for MLS only attributes
 145  * @sid: the SID
 146  *
 147  * Description:
 148  * Call the NetLabel mechanism to get the security attributes of the given
 149  * packet and use those attributes to determine the correct context/SID to
 150  * assign to the packet.  Returns zero on success, negative values on failure.
 151  *
 152  */
 153 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u32 base_sid, u32 *sid)
 154 {
 155         int rc;
 156         struct netlbl_lsm_secattr secattr;
 157
 158         if (!netlbl_enabled()) {
 159                 *sid = SECSID_NULL;
 160                 return 0;
 161         }
 162
 163         netlbl_secattr_init(&secattr);
 164         rc = netlbl_skbuff_getattr(skb, &secattr);
 165         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE) {
 166                 rc = security_netlbl_secattr_to_sid(&secattr, base_sid, sid);
 167                 if (rc == 0 &&
 168                     (secattr.flags & NETLBL_SECATTR_CACHEABLE) &&
 169                     (secattr.flags & NETLBL_SECATTR_CACHE))
 170                         netlbl_cache_add(skb, &secattr);
 171         } else
 172                 *sid = SECSID_NULL;
 173         netlbl_secattr_destroy(&secattr);
 174
 175         return rc;
 176 }
 177
 178 /**
 179  * selinux_netlbl_sock_graft - Netlabel the new socket
 180  * @sk: the new connection
 181  * @sock: the new socket
 182  *
 183  * Description:
 184  * The connection represented by @sk is being grafted onto @sock so set the
 185  * socket's NetLabel to match the SID of @sk.
 186  *
 187  */
 188 void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
 189 {
 190         struct inode_security_struct *isec = SOCK_INODE(sock)->i_security;
 191         struct sk_security_struct *sksec = sk->sk_security;
 192         struct netlbl_lsm_secattr secattr;
 193         u32 nlbl_peer_sid;
 194
 195         sksec->sclass = isec->sclass;
 196
 197         rcu_read_lock();
 198
 199         if (sksec->nlbl_state != NLBL_REQUIRE) {
 200                 rcu_read_unlock();
 201                 return;
 202         }
 203
 204         netlbl_secattr_init(&secattr);
 205         if (netlbl_sock_getattr(sk, &secattr) == 0 &&
 206             secattr.flags != NETLBL_SECATTR_NONE &&
 207             security_netlbl_secattr_to_sid(&secattr,
 208                                            SECINITSID_NETMSG,
 209                                            &nlbl_peer_sid) == 0)
 210                 sksec->peer_sid = nlbl_peer_sid;
 211         netlbl_secattr_destroy(&secattr);
 212
 213         /* Try to set the NetLabel on the socket to save time later, if we fail
 214          * here we will pick up the pieces in later calls to
 215          * selinux_netlbl_inode_permission(). */
 216         selinux_netlbl_sock_setsid(sk, sksec->sid);
 217
 218         rcu_read_unlock();
 219 }
 220
 221 /**
 222  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 223  * @sock: the socket to label
 224  *
 225  * Description:
 226  * Attempt to label a socket using the NetLabel mechanism using the given
 227  * SID.  Returns zero values on success, negative values on failure.
 228  *
 229  */
 230 int selinux_netlbl_socket_post_create(struct socket *sock)
 231 {
 232         int rc = 0;
 233         struct sock *sk = sock->sk;
 234         struct inode_security_struct *isec = SOCK_INODE(sock)->i_security;
 235         struct sk_security_struct *sksec = sk->sk_security;
 236
 237         sksec->sclass = isec->sclass;
 238
 239         rcu_read_lock();
 240         if (sksec->nlbl_state == NLBL_REQUIRE)
 241                 rc = selinux_netlbl_sock_setsid(sk, sksec->sid);
 242         rcu_read_unlock();
 243
 244         return rc;
 245 }
 246
 247 /**
 248  * selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
 249  * @inode: the file descriptor's inode
 250  * @mask: the permission mask
 251  *
 252  * Description:
 253  * Looks at a file's inode and if it is marked as a socket protected by
 254  * NetLabel then verify that the socket has been labeled, if not try to label
 255  * the socket now with the inode's SID.  Returns zero on success, negative
 256  * values on failure.
 257  *
 258  */
 259 int selinux_netlbl_inode_permission(struct inode *inode, int mask)
 260 {
 261         int rc;
 262         struct sock *sk;
 263         struct socket *sock;
 264         struct sk_security_struct *sksec;
 265
 266         if (!S_ISSOCK(inode->i_mode) ||
 267             ((mask & (MAY_WRITE | MAY_APPEND)) == 0))
 268                 return 0;
 269         sock = SOCKET_I(inode);
 270         sk = sock->sk;
 271         sksec = sk->sk_security;
 272
 273         rcu_read_lock();
 274         if (sksec->nlbl_state != NLBL_REQUIRE) {
 275                 rcu_read_unlock();
 276                 return 0;
 277         }
 278         local_bh_disable();
 279         bh_lock_sock_nested(sk);
 280         rc = selinux_netlbl_sock_setsid(sk, sksec->sid);
 281         bh_unlock_sock(sk);
 282         local_bh_enable();
 283         rcu_read_unlock();
 284
 285         return rc;
 286 }
 287
 288 /**
 289  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 290  * @sksec: the sock's sk_security_struct
 291  * @skb: the packet
 292  * @ad: the audit data
 293  *
 294  * Description:
 295  * Fetch the NetLabel security attributes from @skb and perform an access check
 296  * against the receiving socket.  Returns zero on success, negative values on
 297  * error.
 298  *
 299  */
 300 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 301                                 struct sk_buff *skb,
 302                                 struct avc_audit_data *ad)
 303 {
 304         int rc;
 305         u32 nlbl_sid;
 306         u32 perm;
 307         struct netlbl_lsm_secattr secattr;
 308
 309         if (!netlbl_enabled())
 310                 return 0;
 311
 312         netlbl_secattr_init(&secattr);
 313         rc = netlbl_skbuff_getattr(skb, &secattr);
 314         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE) {
 315                 rc = security_netlbl_secattr_to_sid(&secattr,
 316                                                     SECINITSID_NETMSG,
 317                                                     &nlbl_sid);
 318                 if (rc == 0 &&
 319                     (secattr.flags & NETLBL_SECATTR_CACHEABLE) &&
 320                     (secattr.flags & NETLBL_SECATTR_CACHE))
 321                         netlbl_cache_add(skb, &secattr);
 322         } else
 323                 nlbl_sid = SECINITSID_UNLABELED;
 324         netlbl_secattr_destroy(&secattr);
 325         if (rc != 0)
 326                 return rc;
 327
 328         switch (sksec->sclass) {
 329         case SECCLASS_UDP_SOCKET:
 330                 perm = UDP_SOCKET__RECVFROM;
 331                 break;
 332         case SECCLASS_TCP_SOCKET:
 333                 perm = TCP_SOCKET__RECVFROM;
 334                 break;
 335         default:
 336                 perm = RAWIP_SOCKET__RECVFROM;
 337         }
 338
 339         rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 340         if (rc == 0)
 341                 return 0;
 342
 343         if (nlbl_sid != SECINITSID_UNLABELED)
 344                 netlbl_skbuff_err(skb, rc);
 345         return rc;
 346 }
 347
 348 /**
 349  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 350  * @sock: the socket
 351  * @level: the socket level or protocol
 352  * @optname: the socket option name
 353  *
 354  * Description:
 355  * Check the setsockopt() call and if the user is trying to replace the IP
 356  * options on a socket and a NetLabel is in place for the socket deny the
 357  * access; otherwise allow the access.  Returns zero when the access is
 358  * allowed, -EACCES when denied, and other negative values on error.
 359  *
 360  */
 361 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 362                                      int level,
 363                                      int optname)
 364 {
 365         int rc = 0;
 366         struct sock *sk = sock->sk;
 367         struct sk_security_struct *sksec = sk->sk_security;
 368         struct netlbl_lsm_secattr secattr;
 369
 370         rcu_read_lock();
 371         if (level == IPPROTO_IP && optname == IP_OPTIONS &&
 372             sksec->nlbl_state == NLBL_LABELED) {
 373                 netlbl_secattr_init(&secattr);
 374                 lock_sock(sk);
 375                 rc = netlbl_sock_getattr(sk, &secattr);
 376                 release_sock(sk);
 377                 if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 378                         rc = -EACCES;
 379                 netlbl_secattr_destroy(&secattr);
 380         }
 381         rcu_read_unlock();
 382
 383         return rc;
 384 }