FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_ipc.c
1 /* $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */
2 /*-
3 * Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca>
4 * Copyright (c) 2006 nCircle Network Security, Inc.
5 * All rights reserved.
6 *
7 * This software was developed by Robert N. M. Watson for the TrustedBSD
8 * Project under contract to nCircle Network Security, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by Herb Peyerl.
21 * 4. The name of Herb Peyerl may not be used to endorse or promote products
22 * derived from this software without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include "opt_sysvipc.h"
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/sem.h>
44 #include <sys/shm.h>
45 #include <sys/ipc.h>
46 #include <sys/priv.h>
47 #include <sys/proc.h>
48 #include <sys/ucred.h>
49
50 void (*shmfork_hook)(struct proc *, struct proc *) = NULL;
51 void (*shmexit_hook)(struct vmspace *) = NULL;
52
53 /* called from kern_fork.c */
54 void
55 shmfork(p1, p2)
56 struct proc *p1, *p2;
57 {
58
59 if (shmfork_hook != NULL)
60 shmfork_hook(p1, p2);
61 return;
62 }
63
64 /* called from kern_exit.c */
65 void
66 shmexit(struct vmspace *vm)
67 {
68
69 if (shmexit_hook != NULL)
70 shmexit_hook(vm);
71 return;
72 }
73
74 /*
75 * Check for IPC permission.
76 *
77 * Note: The MAC Framework does not require any modifications to the
78 * ipcperm() function, as access control checks are performed throughout the
79 * implementation of each primitive. Those entry point calls complement the
80 * ipcperm() discertionary checks. Unlike file system discretionary access
81 * control, the original create of an object is given the same rights as the
82 * current owner.
83 */
84 int
85 ipcperm(struct thread *td, struct ipc_perm *perm, int acc_mode)
86 {
87 struct ucred *cred = td->td_ucred;
88 int error, obj_mode, dac_granted, priv_granted;
89
90 dac_granted = 0;
91 if (cred->cr_uid == perm->cuid || cred->cr_uid == perm->uid) {
92 obj_mode = perm->mode;
93 dac_granted |= IPC_M;
94 } else if (groupmember(perm->gid, cred) ||
95 groupmember(perm->cgid, cred)) {
96 obj_mode = perm->mode;
97 obj_mode <<= 3;
98 } else {
99 obj_mode = perm->mode;
100 obj_mode <<= 6;
101 }
102
103 /*
104 * While the System V IPC permission model allows IPC_M to be
105 * granted, as part of the mode, our implementation requires
106 * privilege to adminster the object if not the owner or creator.
107 */
108 #if 0
109 if (obj_mode & IPC_M)
110 dac_granted |= IPC_M;
111 #endif
112 if (obj_mode & IPC_R)
113 dac_granted |= IPC_R;
114 if (obj_mode & IPC_W)
115 dac_granted |= IPC_W;
116
117 /*
118 * Simple case: all required rights are granted by DAC.
119 */
120 if ((dac_granted & acc_mode) == acc_mode)
121 return (0);
122
123 /*
124 * Privilege is required to satisfy the request.
125 */
126 priv_granted = 0;
127 if ((acc_mode & IPC_M) && !(dac_granted & IPC_M)) {
128 error = priv_check(td, PRIV_IPC_ADMIN);
129 if (error == 0)
130 priv_granted |= IPC_M;
131 }
132
133 if ((acc_mode & IPC_R) && !(dac_granted & IPC_R)) {
134 error = priv_check(td, PRIV_IPC_READ);
135 if (error == 0)
136 priv_granted |= IPC_R;
137 }
138
139 if ((acc_mode & IPC_W) && !(dac_granted & IPC_W)) {
140 error = priv_check(td, PRIV_IPC_WRITE);
141 if (error == 0)
142 priv_granted |= IPC_W;
143 }
144
145 if (((dac_granted | priv_granted) & acc_mode) == acc_mode)
146 return (0);
147 else
148 return (EACCES);
149 }
150
151 void
152 ipcperm_old2new(struct ipc_perm_old *old, struct ipc_perm *new)
153 {
154
155 new->cuid = old->cuid;
156 new->cgid = old->cgid;
157 new->uid = old->uid;
158 new->gid = old->gid;
159 new->mode = old->mode;
160 new->seq = old->seq;
161 new->key = old->key;
162 }
163
164 void
165 ipcperm_new2old(struct ipc_perm *new, struct ipc_perm_old *old)
166 {
167
168 /* XXX: How to handle ID's > USHORT_MAX? */
169 old->cuid = new->cuid;
170 old->cgid = new->cgid;
171 old->uid = new->uid;
172 old->gid = new->gid;
173 old->mode = new->mode;
174 old->seq = new->seq;
175 old->key = new->key;
176 }
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