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