xnu-6153.81.5.tar.gz

[apple/xnu.git] / bsd / kern / sysv_ipc.c

diff --git a/bsd/kern/sysv_ipc.c b/bsd/kern/sysv_ipc.c
index 789d379da4e39a15b58c526e7b66e263f6dc5cb3..926ce9f7e43f92d6695ad8bf3c87bfe581382d7f 100644 (file)
--- a/bsd/kern/sysv_ipc.c
+++ b/bsd/kern/sysv_ipc.c
@@ -1,15 +1,20 @@
 /*
  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
  *
 /*
  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
  *

- * @APPLE_LICENSE_HEADER_START@
- * 
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ *

  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in
  * This file contains Original Code and/or Modifications of Original Code
  * as defined in and that are subject to the Apple Public Source License
  * Version 2.0 (the 'License'). You may not use this file except in

- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- * 
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ *

  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,


@@ -17,8 +22,8 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.

- * 
- * @APPLE_LICENSE_HEADER_END@
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@

  */
 /*     $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */
 
  */
 /*     $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */
 


@@ -55,39 +60,104 @@
 
 #include <sys/param.h>
 #include <sys/ipc.h>
 
 #include <sys/param.h>
 #include <sys/ipc.h>

+#include <sys/stat.h>   /* mode constants */

 #include <sys/ucred.h>
 #include <sys/kauth.h>
 
 
 /*
  * Check for ipc permission
 #include <sys/ucred.h>
 #include <sys/kauth.h>
 
 
 /*
  * Check for ipc permission

- *
- * XXX: Should pass proc argument so that we can pass 
- * XXX: proc->p_acflag to suser()

  */
 
  */
 

+
+/*
+ * ipc_perm
+ *
+ *     perm->mode                      mode of the object
+ *     mode                            mode bits we want to test
+ *
+ * Returns:    0                       Success
+ *             EPERM
+ *             EACCES
+ *
+ * Notes:      The IPC_M bit is special, in that it may only be granted to
+ *             root, the creating user, or the owning user.
+ *
+ *             This code does not use posix_cred_access() because of the
+ *             need to check both creator and owner separately when we are
+ *             considering a rights grant.  Because of this, we need to do
+ *             two evaluations when the values are inequal, which can lead
+ *             us to defeat the callout avoidance optimization.  So we do
+ *             the work here, inline.  This is less than optimal for any
+ *             future work involving opacity of of POSIX credentials.
+ *
+ *             Setting up the mode_owner / mode_group / mode_world implicitly
+ *             masks the IPC_M bit off.  This is intentional.
+ *
+ *             See the posix_cred_access() implementation for algorithm
+ *             information.
+ */

 int
 int

-ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode)
+ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode_req)

 {
 {

+       uid_t   uid = kauth_cred_getuid(cred);  /* avoid multiple calls */
+       int     want_mod_controlinfo = (mode_req & IPC_M);
+       int     is_member;
+       mode_t  mode_owner = (perm->mode & S_IRWXU);
+       mode_t  mode_group = (perm->mode & S_IRWXG) << 3;
+       mode_t  mode_world = (perm->mode & S_IRWXO) << 6;

 
 

-       if (!suser(cred, (u_short *)NULL))
-               return (0);
+       /* Grant all rights to super user */
+       if (!suser(cred, (u_short *)NULL)) {
+               return 0;
+       }

 
 

-       /* Check for user match. */
-       if (kauth_cred_getuid(cred) != perm->cuid && kauth_cred_getuid(cred) != perm->uid) {
-               int is_member;
+       /* Grant or deny rights based on ownership */
+       if (uid == perm->cuid || uid == perm->uid) {
+               if (want_mod_controlinfo) {
+                       return 0;
+               }

 
 

-               if (mode & IPC_M)
-                       return (EPERM);
-               /* Check for group match. */
-               mode >>= 3;
-               if ((kauth_cred_ismember_gid(cred, perm->gid, &is_member) || !is_member) &&
-                   (kauth_cred_ismember_gid(cred, perm->cgid, &is_member) || !is_member))
-                       /* Check for `other' match. */
-                       mode >>= 3;
+               return (mode_req & mode_owner) == mode_req ? 0 : EACCES;
+       } else {
+               /* everyone else who wants to modify control info is denied */
+               if (want_mod_controlinfo) {
+                       return EPERM;
+               }

        }
 
        }
 

-       if (mode & IPC_M)
-               return (0);
-       return ((mode & perm->mode) == mode ? 0 : EACCES);
+       /*
+        * Combined group and world rights check, if no owner rights; positive
+        * asssertion of gid/cgid equality avoids an extra callout in the
+        * common case.
+        */
+       if ((mode_req & mode_group & mode_world) == mode_req) {
+               return 0;
+       } else {
+               if ((mode_req & mode_group) != mode_req) {
+                       if ((!kauth_cred_ismember_gid(cred, perm->gid, &is_member) && is_member) &&
+                           ((perm->gid == perm->cgid) ||
+                           (!kauth_cred_ismember_gid(cred, perm->cgid, &is_member) && is_member))) {
+                               return EACCES;
+                       } else {
+                               if ((mode_req & mode_world) != mode_req) {
+                                       return EACCES;
+                               } else {
+                                       return 0;
+                               }
+                       }
+               } else {
+                       if ((!kauth_cred_ismember_gid(cred, perm->gid, &is_member) && is_member) ||
+                           ((perm->gid != perm->cgid) &&
+                           (!kauth_cred_ismember_gid(cred, perm->cgid, &is_member) && is_member))) {
+                               return 0;
+                       } else {
+                               if ((mode_req & mode_world) != mode_req) {
+                                       return EACCES;
+                               } else {
+                                       return 0;
+                               }
+                       }
+               }
+       }

 }
 }