xref: /freebsd/sys/kern/sysv_ipc.c (revision 52f72944b8f5abb2386eae924357dee8aea17d5b)
1 /*-
2  * SPDX-License-Identifier: BSD-4-Clause
3  *
4  * Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca>
5  * Copyright (c) 2006 nCircle Network Security, Inc.
6  * All rights reserved.
7  *
8  * This software was developed by Robert N. M. Watson for the TrustedBSD
9  * Project under contract to nCircle Network Security, Inc.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *      This product includes software developed by Herb Peyerl.
22  * 4. The name of Herb Peyerl may not be used to endorse or promote products
23  *    derived from this software without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35  *
36  * $NetBSD: sysv_ipc.c,v 1.9 1995/06/02 19:04:22 mycroft Exp $
37  */
38 
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
41 
42 #include "opt_compat.h"
43 #include "opt_sysvipc.h"
44 
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/sem.h>
48 #include <sys/shm.h>
49 #include <sys/ipc.h>
50 #include <sys/priv.h>
51 #include <sys/proc.h>
52 #include <sys/ucred.h>
53 
54 void (*shmfork_hook)(struct proc *, struct proc *) = NULL;
55 void (*shmexit_hook)(struct vmspace *) = NULL;
56 
57 /* called from kern_fork.c */
58 void
59 shmfork(p1, p2)
60 	struct proc *p1, *p2;
61 {
62 
63 	if (shmfork_hook != NULL)
64 		shmfork_hook(p1, p2);
65 	return;
66 }
67 
68 /* called from kern_exit.c */
69 void
70 shmexit(struct vmspace *vm)
71 {
72 
73 	if (shmexit_hook != NULL)
74 		shmexit_hook(vm);
75 	return;
76 }
77 
78 /*
79  * Check for IPC permission.
80  *
81  * Note: The MAC Framework does not require any modifications to the
82  * ipcperm() function, as access control checks are performed throughout the
83  * implementation of each primitive.  Those entry point calls complement the
84  * ipcperm() discertionary checks.  Unlike file system discretionary access
85  * control, the original create of an object is given the same rights as the
86  * current owner.
87  */
88 int
89 ipcperm(struct thread *td, struct ipc_perm *perm, int acc_mode)
90 {
91 	struct ucred *cred = td->td_ucred;
92 	int error, obj_mode, dac_granted, priv_granted;
93 
94 	dac_granted = 0;
95 	if (cred->cr_uid == perm->cuid || cred->cr_uid == perm->uid) {
96 		obj_mode = perm->mode;
97 		dac_granted |= IPC_M;
98 	} else if (groupmember(perm->gid, cred) ||
99 	    groupmember(perm->cgid, cred)) {
100 		obj_mode = perm->mode;
101 		obj_mode <<= 3;
102 	} else {
103 		obj_mode = perm->mode;
104 		obj_mode <<= 6;
105 	}
106 
107 	/*
108 	 * While the System V IPC permission model allows IPC_M to be
109 	 * granted, as part of the mode, our implementation requires
110 	 * privilege to adminster the object if not the owner or creator.
111 	 */
112 #if 0
113 	if (obj_mode & IPC_M)
114 		dac_granted |= IPC_M;
115 #endif
116 	if (obj_mode & IPC_R)
117 		dac_granted |= IPC_R;
118 	if (obj_mode & IPC_W)
119 		dac_granted |= IPC_W;
120 
121 	/*
122 	 * Simple case: all required rights are granted by DAC.
123 	 */
124 	if ((dac_granted & acc_mode) == acc_mode)
125 		return (0);
126 
127 	/*
128 	 * Privilege is required to satisfy the request.
129 	 */
130 	priv_granted = 0;
131 	if ((acc_mode & IPC_M) && !(dac_granted & IPC_M)) {
132 		error = priv_check(td, PRIV_IPC_ADMIN);
133 		if (error == 0)
134 			priv_granted |= IPC_M;
135 	}
136 
137 	if ((acc_mode & IPC_R) && !(dac_granted & IPC_R)) {
138 		error = priv_check(td, PRIV_IPC_READ);
139 		if (error == 0)
140 			priv_granted |= IPC_R;
141 	}
142 
143 	if ((acc_mode & IPC_W) && !(dac_granted & IPC_W)) {
144 		error = priv_check(td, PRIV_IPC_WRITE);
145 		if (error == 0)
146 			priv_granted |= IPC_W;
147 	}
148 
149 	if (((dac_granted | priv_granted) & acc_mode) == acc_mode)
150 		return (0);
151 	else
152 		return (EACCES);
153 }
154 
155 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
156     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
157 void
158 ipcperm_old2new(struct ipc_perm_old *old, struct ipc_perm *new)
159 {
160 
161 	new->cuid = old->cuid;
162 	new->cgid = old->cgid;
163 	new->uid = old->uid;
164 	new->gid = old->gid;
165 	new->mode = old->mode;
166 	new->seq = old->seq;
167 	new->key = old->key;
168 }
169 
170 void
171 ipcperm_new2old(struct ipc_perm *new, struct ipc_perm_old *old)
172 {
173 
174 	/* XXX: How to handle ID's > USHORT_MAX? */
175 	old->cuid = new->cuid;
176 	old->cgid = new->cgid;
177 	old->uid = new->uid;
178 	old->gid = new->gid;
179 	old->mode = new->mode;
180 	old->seq = new->seq;
181 	old->key = new->key;
182 }
183 #endif
184 
185 #ifdef COMPAT_FREEBSD32
186 #include <sys/mount.h>
187 #include <sys/socket.h>
188 #include <compat/freebsd32/freebsd32.h>
189 #include <compat/freebsd32/freebsd32_ipc.h>
190 #include <compat/freebsd32/freebsd32_proto.h>
191 #include <compat/freebsd32/freebsd32_signal.h>
192 #include <compat/freebsd32/freebsd32_syscall.h>
193 #include <compat/freebsd32/freebsd32_util.h>
194 
195 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
196     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
197 void
198 freebsd32_ipcperm_old_in(struct ipc_perm32_old *ip32, struct ipc_perm *ip)
199 {
200 
201 	CP(*ip32, *ip, cuid);
202 	CP(*ip32, *ip, cgid);
203 	CP(*ip32, *ip, uid);
204 	CP(*ip32, *ip, gid);
205 	CP(*ip32, *ip, mode);
206 	CP(*ip32, *ip, seq);
207 	CP(*ip32, *ip, key);
208 }
209 
210 void
211 freebsd32_ipcperm_old_out(struct ipc_perm *ip, struct ipc_perm32_old *ip32)
212 {
213 
214 	CP(*ip, *ip32, cuid);
215 	CP(*ip, *ip32, cgid);
216 	CP(*ip, *ip32, uid);
217 	CP(*ip, *ip32, gid);
218 	CP(*ip, *ip32, mode);
219 	CP(*ip, *ip32, seq);
220 	CP(*ip, *ip32, key);
221 }
222 #endif
223 
224 void
225 freebsd32_ipcperm_in(struct ipc_perm32 *ip32, struct ipc_perm *ip)
226 {
227 
228 	CP(*ip32, *ip, cuid);
229 	CP(*ip32, *ip, cgid);
230 	CP(*ip32, *ip, uid);
231 	CP(*ip32, *ip, gid);
232 	CP(*ip32, *ip, mode);
233 	CP(*ip32, *ip, seq);
234 	CP(*ip32, *ip, key);
235 }
236 
237 void
238 freebsd32_ipcperm_out(struct ipc_perm *ip, struct ipc_perm32 *ip32)
239 {
240 
241 	CP(*ip, *ip32, cuid);
242 	CP(*ip, *ip32, cgid);
243 	CP(*ip, *ip32, uid);
244 	CP(*ip, *ip32, gid);
245 	CP(*ip, *ip32, mode);
246 	CP(*ip, *ip32, seq);
247 	CP(*ip, *ip32, key);
248 }
249 #endif
250