1/* 2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28/* $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */ 29 30/* 31 * Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca> 32 * All rights reserved. 33 * 34 * Redistribution and use in source and binary forms, with or without 35 * modification, are permitted provided that the following conditions 36 * are met: 37 * 1. Redistributions of source code must retain the above copyright 38 * notice, this list of conditions and the following disclaimer. 39 * 2. Redistributions in binary form must reproduce the above copyright 40 * notice, this list of conditions and the following disclaimer in the 41 * documentation and/or other materials provided with the distribution. 42 * 3. All advertising materials mentioning features or use of this software 43 * must display the following acknowledgement: 44 * This product includes software developed by Herb Peyerl. 45 * 4. The name of Herb Peyerl may not be used to endorse or promote products 46 * derived from this software without specific prior written permission. 47 * 48 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 49 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 50 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 51 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 52 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 53 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 54 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 55 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 56 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 57 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 58 */ 59 60 61#include <sys/param.h> 62#include <sys/ipc.h> 63#include <sys/stat.h> /* mode constants */ 64#include <sys/ucred.h> 65#include <sys/kauth.h> 66 67 68/* 69 * Check for ipc permission 70 */ 71 72 73/* 74 * ipc_perm 75 * 76 * perm->mode mode of the object 77 * mode mode bits we want to test 78 * 79 * Returns: 0 Success 80 * EPERM 81 * EACCES 82 * 83 * Notes: The IPC_M bit is special, in that it may only be granted to 84 * root, the creating user, or the owning user. 85 * 86 * This code does not use posix_cred_access() because of the 87 * need to check both creator and owner separately when we are 88 * considering a rights grant. Because of this, we need to do 89 * two evaluations when the values are inequal, which can lead 90 * us to defeat the callout avoidance optimization. So we do 91 * the work here, inline. This is less than optimal for any 92 * future work involving opacity of of POSIX credentials. 93 * 94 * Setting up the mode_owner / mode_group / mode_world implicitly 95 * masks the IPC_M bit off. This is intentional. 96 * 97 * See the posix_cred_access() implementation for algorithm 98 * information. 99 */ 100int 101ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode_req) 102{ 103 uid_t uid = kauth_cred_getuid(cred); /* avoid multiple calls */ 104 int want_mod_controlinfo = (mode_req & IPC_M); 105 int is_member; 106 mode_t mode_owner = (perm->mode & S_IRWXU); 107 mode_t mode_group = (perm->mode & S_IRWXG) << 3; 108 mode_t mode_world = (perm->mode & S_IRWXO) << 6; 109 110 /* Grant all rights to super user */ 111 if (!suser(cred, (u_short *)NULL)) 112 return (0); 113 114 /* Grant or deny rights based on ownership */ 115 if (uid == perm->cuid || uid == perm->uid) { 116 if (want_mod_controlinfo) 117 return (0); 118 119 return ((mode_req & mode_owner) == mode_req ? 0 : EACCES); 120 } else { 121 /* everyone else who wants to modify control info is denied */ 122 if (want_mod_controlinfo) 123 return (EPERM); 124 } 125 126 /* 127 * Combined group and world rights check, if no owner rights; positive 128 * asssertion of gid/cgid equality avoids an extra callout in the 129 * common case. 130 */ 131 if ((mode_req & mode_group & mode_world) == mode_req) { 132 return (0); 133 } else { 134 if ((mode_req & mode_group) != mode_req) { 135 if ((!kauth_cred_ismember_gid(cred, perm->gid, &is_member) && is_member) && 136 ((perm->gid == perm->cgid) || 137 (!kauth_cred_ismember_gid(cred, perm->cgid, &is_member) && is_member))) { 138 return (EACCES); 139 } else { 140 if ((mode_req & mode_world) != mode_req) { 141 return (EACCES); 142 } else { 143 return (0); 144 } 145 } 146 } else { 147 if ((!kauth_cred_ismember_gid(cred, perm->gid, &is_member) && is_member) || 148 ((perm->gid != perm->cgid) && 149 (!kauth_cred_ismember_gid(cred, perm->cgid, &is_member) && is_member))) { 150 return (0); 151 } else { 152 if ((mode_req & mode_world) != mode_req) { 153 return (EACCES); 154 } else { 155 return (0); 156 } 157 } 158 } 159 } 160} 161