freebsd-skq/sys/kern/sysv_ipc.c
dillon ce710d36cc It is possible for an active aio to prevent shared memory from being
dereferenced when a process exits due to the vmspace ref-count being
bumped.  Change shmexit() and shmexit_myhook() to take a vmspace instead
of a process and call it in vmspace_dofree().  This way if it is missed
in exit1()'s early-resource-free it will still be caught when the zombie is
reaped.

Also fix a potential race in shmexit_myhook() by NULLing out
vmspace->vm_shm prior to calling shm_delete_mapping() and free().

MFC after:	7 days
2003-01-13 23:04:32 +00:00

97 lines
2.8 KiB
C

/* $FreeBSD$ */
/* $NetBSD: sysv_ipc.c,v 1.7 1994/06/29 06:33:11 cgd Exp $ */
/*
* Copyright (c) 1994 Herb Peyerl <hpeyerl@novatel.ca>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Herb Peyerl.
* 4. The name of Herb Peyerl may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "opt_sysvipc.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/ipc.h>
#include <sys/proc.h>
#include <sys/ucred.h>
void (*shmfork_hook)(struct proc *, struct proc *) = NULL;
void (*shmexit_hook)(struct vmspace *) = NULL;
/* called from kern_fork.c */
void
shmfork(p1, p2)
struct proc *p1, *p2;
{
if (shmfork_hook != NULL)
shmfork_hook(p1, p2);
return;
}
/* called from kern_exit.c */
void
shmexit(struct vmspace *vm)
{
if (shmexit_hook != NULL)
shmexit_hook(vm);
return;
}
/*
* Check for ipc permission
*/
int
ipcperm(td, perm, mode)
struct thread *td;
struct ipc_perm *perm;
int mode;
{
struct ucred *cred = td->td_ucred;
/* Check for user match. */
if (cred->cr_uid != perm->cuid && cred->cr_uid != perm->uid) {
if (mode & IPC_M)
return (suser(td) == 0 ? 0 : EPERM);
/* Check for group match. */
mode >>= 3;
if (!groupmember(perm->gid, cred) &&
!groupmember(perm->cgid, cred))
/* Check for `other' match. */
mode >>= 3;
}
if (mode & IPC_M)
return (0);
return ((mode & perm->mode) == mode ||
suser(td) == 0 ? 0 : EACCES);
}