/* * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. * * @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 * 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, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * 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_OSREFERENCE_LICENSE_HEADER_END@ */ /* $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */ /* * Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Herb Peyerl. * 4. The name of Herb Peyerl may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #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 */ /* * 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 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; /* Grant all rights to super user */ if (!suser(cred, (u_short *)NULL)) return (0); /* Grant or deny rights based on ownership */ if (uid == perm->cuid || uid == perm->uid) { if (want_mod_controlinfo) return (0); 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); } /* * 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); } } } } }