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 | */ |
100 | int |
101 | ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode_req) |
102 | { |
103 | uid_t uid = kauth_cred_getuid(cred: 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 = (mode_t)((perm->mode & S_IRWXG) << 3); |
108 | mode_t mode_world = (mode_t)((perm->mode & S_IRWXO) << 6); |
109 | |
110 | /* Grant all rights to super user */ |
111 | if (!suser(cred, acflag: (u_short *)NULL)) { |
112 | return 0; |
113 | } |
114 | |
115 | /* Grant or deny rights based on ownership */ |
116 | if (uid == perm->cuid || uid == perm->uid) { |
117 | if (want_mod_controlinfo) { |
118 | return 0; |
119 | } |
120 | |
121 | return (mode_req & mode_owner) == mode_req ? 0 : EACCES; |
122 | } else { |
123 | /* everyone else who wants to modify control info is denied */ |
124 | if (want_mod_controlinfo) { |
125 | return EPERM; |
126 | } |
127 | } |
128 | |
129 | /* |
130 | * Combined group and world rights check, if no owner rights; positive |
131 | * asssertion of gid/cgid equality avoids an extra callout in the |
132 | * common case. |
133 | */ |
134 | if ((mode_req & mode_group & mode_world) == mode_req) { |
135 | return 0; |
136 | } else { |
137 | if ((mode_req & mode_group) != mode_req) { |
138 | if ((!kauth_cred_ismember_gid(cred: cred, gid: perm->gid, resultp: &is_member) && is_member) && |
139 | ((perm->gid == perm->cgid) || |
140 | (!kauth_cred_ismember_gid(cred: cred, gid: perm->cgid, resultp: &is_member) && is_member))) { |
141 | return EACCES; |
142 | } else { |
143 | if ((mode_req & mode_world) != mode_req) { |
144 | return EACCES; |
145 | } else { |
146 | return 0; |
147 | } |
148 | } |
149 | } else { |
150 | if ((!kauth_cred_ismember_gid(cred: cred, gid: perm->gid, resultp: &is_member) && is_member) || |
151 | ((perm->gid != perm->cgid) && |
152 | (!kauth_cred_ismember_gid(cred: cred, gid: perm->cgid, resultp: &is_member) && is_member))) { |
153 | return 0; |
154 | } else { |
155 | if ((mode_req & mode_world) != mode_req) { |
156 | return EACCES; |
157 | } else { |
158 | return 0; |
159 | } |
160 | } |
161 | } |
162 | } |
163 | } |
164 | |