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 #include "netlabel.h"
  38
  39 /**
  40  * selinux_netlbl_sidlookup_cached - Cache a SID lookup
  41  * @skb: the packet
  42  * @secattr: the NetLabel security attributes
  43  * @sid: the SID
  44  *
  45  * Description:
  46  * Query the SELinux security server to lookup the correct SID for the given
  47  * security attributes.  If the query is successful, cache the result to speed
  48  * up future lookups.  Returns zero on success, negative values on failure.
  49  *
  50  */
  51 static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
  52                                            struct netlbl_lsm_secattr *secattr,
  53                                            u32 *sid)
  54 {
  55         int rc;
  56
  57         rc = security_netlbl_secattr_to_sid(secattr, sid);
  58         if (rc == 0 &&
  59             (secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
  60             (secattr->flags & NETLBL_SECATTR_CACHE))
  61                 netlbl_cache_add(skb, secattr);
  62
  63         return rc;
  64 }
  65
  66 /**
  67  * selinux_netlbl_sock_setsid - Label a socket using the NetLabel mechanism
  68  * @sk: the socket to label
  69  * @sid: the SID to use
  70  *
  71  * Description:
  72  * Attempt to label a socket using the NetLabel mechanism using the given
  73  * SID.  Returns zero values on success, negative values on failure.
  74  *
  75  */
  76 static int selinux_netlbl_sock_setsid(struct sock *sk, u32 sid)
  77 {
  78         int rc;
  79         struct sk_security_struct *sksec = sk->sk_security;
  80         struct netlbl_lsm_secattr secattr;
  81
  82         netlbl_secattr_init(&secattr);
  83
  84         rc = security_netlbl_sid_to_secattr(sid, &secattr);
  85         if (rc != 0)
  86                 goto sock_setsid_return;
  87         rc = netlbl_sock_setattr(sk, &secattr);
  88         if (rc == 0)
  89                 sksec->nlbl_state = NLBL_LABELED;
  90
  91 sock_setsid_return:
  92         netlbl_secattr_destroy(&secattr);
  93         return rc;
  94 }
  95
  96 /**
  97  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
  98  *
  99  * Description:
 100  * Invalidate the NetLabel security attribute mapping cache.
 101  *
 102  */
 103 void selinux_netlbl_cache_invalidate(void)
 104 {
 105         netlbl_cache_invalidate();
 106 }
 107
 108 /**
 109  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 110  * @ssec: the sk_security_struct
 111  * @family: the socket family
 112  *
 113  * Description:
 114  * Called when the NetLabel state of a sk_security_struct needs to be reset.
 115  * The caller is responsibile for all the NetLabel sk_security_struct locking.
 116  *
 117  */
 118 void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
 119                                       int family)
 120 {
 121         if (family == PF_INET)
 122                 ssec->nlbl_state = NLBL_REQUIRE;
 123         else
 124                 ssec->nlbl_state = NLBL_UNSET;
 125 }
 126
 127 /**
 128  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 129  * @skb: the packet
 130  * @family: protocol family
 131  * @type: NetLabel labeling protocol type
 132  * @sid: the SID
 133  *
 134  * Description:
 135  * Call the NetLabel mechanism to get the security attributes of the given
 136  * packet and use those attributes to determine the correct context/SID to
 137  * assign to the packet.  Returns zero on success, negative values on failure.
 138  *
 139  */
 140 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 141                                  u16 family,
 142                                  u32 *type,
 143                                  u32 *sid)
 144 {
 145         int rc;
 146         struct netlbl_lsm_secattr secattr;
 147
 148         if (!netlbl_enabled()) {
 149                 *sid = SECSID_NULL;
 150                 return 0;
 151         }
 152
 153         netlbl_secattr_init(&secattr);
 154         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 155         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 156                 rc = selinux_netlbl_sidlookup_cached(skb, &secattr, sid);
 157         else
 158                 *sid = SECSID_NULL;
 159         *type = secattr.type;
 160         netlbl_secattr_destroy(&secattr);
 161
 162         return rc;
 163 }
 164
 165 /**
 166  * selinux_netlbl_sock_graft - Netlabel the new socket
 167  * @sk: the new connection
 168  * @sock: the new socket
 169  *
 170  * Description:
 171  * The connection represented by @sk is being grafted onto @sock so set the
 172  * socket's NetLabel to match the SID of @sk.
 173  *
 174  */
 175 void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
 176 {
 177         struct sk_security_struct *sksec = sk->sk_security;
 178         struct netlbl_lsm_secattr secattr;
 179         u32 nlbl_peer_sid;
 180
 181         if (sksec->nlbl_state != NLBL_REQUIRE)
 182                 return;
 183
 184         netlbl_secattr_init(&secattr);
 185         if (netlbl_sock_getattr(sk, &secattr) == 0 &&
 186             secattr.flags != NETLBL_SECATTR_NONE &&
 187             security_netlbl_secattr_to_sid(&secattr, &nlbl_peer_sid) == 0)
 188                 sksec->peer_sid = nlbl_peer_sid;
 189         netlbl_secattr_destroy(&secattr);
 190
 191         /* Try to set the NetLabel on the socket to save time later, if we fail
 192          * here we will pick up the pieces in later calls to
 193          * selinux_netlbl_inode_permission(). */
 194         selinux_netlbl_sock_setsid(sk, sksec->sid);
 195 }
 196
 197 /**
 198  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 199  * @sock: the socket to label
 200  *
 201  * Description:
 202  * Attempt to label a socket using the NetLabel mechanism using the given
 203  * SID.  Returns zero values on success, negative values on failure.
 204  *
 205  */
 206 int selinux_netlbl_socket_post_create(struct socket *sock)
 207 {
 208         struct sock *sk = sock->sk;
 209         struct sk_security_struct *sksec = sk->sk_security;
 210
 211         if (sksec->nlbl_state != NLBL_REQUIRE)
 212                 return 0;
 213
 214         return selinux_netlbl_sock_setsid(sk, sksec->sid);
 215 }
 216
 217 /**
 218  * selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
 219  * @inode: the file descriptor's inode
 220  * @mask: the permission mask
 221  *
 222  * Description:
 223  * Looks at a file's inode and if it is marked as a socket protected by
 224  * NetLabel then verify that the socket has been labeled, if not try to label
 225  * the socket now with the inode's SID.  Returns zero on success, negative
 226  * values on failure.
 227  *
 228  */
 229 int selinux_netlbl_inode_permission(struct inode *inode, int mask)
 230 {
 231         int rc;
 232         struct sock *sk;
 233         struct socket *sock;
 234         struct sk_security_struct *sksec;
 235
 236         if (!S_ISSOCK(inode->i_mode) ||
 237             ((mask & (MAY_WRITE | MAY_APPEND)) == 0))
 238                 return 0;
 239
 240         sock = SOCKET_I(inode);
 241         sk = sock->sk;
 242         sksec = sk->sk_security;
 243         if (sksec->nlbl_state != NLBL_REQUIRE)
 244                 return 0;
 245
 246         local_bh_disable();
 247         bh_lock_sock_nested(sk);
 248         if (likely(sksec->nlbl_state == NLBL_REQUIRE))
 249                 rc = selinux_netlbl_sock_setsid(sk, sksec->sid);
 250         else
 251                 rc = 0;
 252         bh_unlock_sock(sk);
 253         local_bh_enable();
 254
 255         return rc;
 256 }
 257
 258 /**
 259  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 260  * @sksec: the sock's sk_security_struct
 261  * @skb: the packet
 262  * @family: protocol family
 263  * @ad: the audit data
 264  *
 265  * Description:
 266  * Fetch the NetLabel security attributes from @skb and perform an access check
 267  * against the receiving socket.  Returns zero on success, negative values on
 268  * error.
 269  *
 270  */
 271 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 272                                 struct sk_buff *skb,
 273                                 u16 family,
 274                                 struct avc_audit_data *ad)
 275 {
 276         int rc;
 277         u32 nlbl_sid;
 278         u32 perm;
 279         struct netlbl_lsm_secattr secattr;
 280
 281         if (!netlbl_enabled())
 282                 return 0;
 283
 284         netlbl_secattr_init(&secattr);
 285         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 286         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 287                 rc = selinux_netlbl_sidlookup_cached(skb, &secattr, &nlbl_sid);
 288         else
 289                 nlbl_sid = SECINITSID_UNLABELED;
 290         netlbl_secattr_destroy(&secattr);
 291         if (rc != 0)
 292                 return rc;
 293
 294         switch (sksec->sclass) {
 295         case SECCLASS_UDP_SOCKET:
 296                 perm = UDP_SOCKET__RECVFROM;
 297                 break;
 298         case SECCLASS_TCP_SOCKET:
 299                 perm = TCP_SOCKET__RECVFROM;
 300                 break;
 301         default:
 302                 perm = RAWIP_SOCKET__RECVFROM;
 303         }
 304
 305         rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 306         if (rc == 0)
 307                 return 0;
 308
 309         if (nlbl_sid != SECINITSID_UNLABELED)
 310                 netlbl_skbuff_err(skb, rc);
 311         return rc;
 312 }
 313
 314 /**
 315  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 316  * @sock: the socket
 317  * @level: the socket level or protocol
 318  * @optname: the socket option name
 319  *
 320  * Description:
 321  * Check the setsockopt() call and if the user is trying to replace the IP
 322  * options on a socket and a NetLabel is in place for the socket deny the
 323  * access; otherwise allow the access.  Returns zero when the access is
 324  * allowed, -EACCES when denied, and other negative values on error.
 325  *
 326  */
 327 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 328                                      int level,
 329                                      int optname)
 330 {
 331         int rc = 0;
 332         struct sock *sk = sock->sk;
 333         struct sk_security_struct *sksec = sk->sk_security;
 334         struct netlbl_lsm_secattr secattr;
 335
 336         if (level == IPPROTO_IP && optname == IP_OPTIONS &&
 337             sksec->nlbl_state == NLBL_LABELED) {
 338                 netlbl_secattr_init(&secattr);
 339                 lock_sock(sk);
 340                 rc = netlbl_sock_getattr(sk, &secattr);
 341                 release_sock(sk);
 342                 if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 343                         rc = -EACCES;
 344                 netlbl_secattr_destroy(&secattr);
 345         }
 346
 347         return rc;
 348 }