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 }