fab63cc413
incomplete and some are just placeholders but I wanted to try to get something at least into 2.2 on the grounds that what I have is a lot better than nothing. I also wanted to commit something which documents the interfaces in 2.2 before I start updating the documentation for 3.0. This is a definite 2.2 candidate and is also relavent to 2.1 if people still care about that branch.
147 lines
3.9 KiB
Groff
147 lines
3.9 KiB
Groff
.\" -*- nroff -*-
|
|
.\" -*- nroff -*-
|
|
.\"
|
|
.\" Copyright (c) 1996 Doug Rabson
|
|
.\"
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This program is free software.
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 DEVELOPERS 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.
|
|
.\"
|
|
.\" $Id$
|
|
.\"
|
|
.Dd July 24, 1996
|
|
.Os
|
|
.Dt VOP_ACCESS 9
|
|
.Sh NAME
|
|
.Nm VOP_ACCESS
|
|
.Nd check access permissions of a file or unix domain socket
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/vnode.h>
|
|
.Ft int
|
|
.Fn VOP_ACCESS "struct vnode *vp" "int mode" "struct ucred *cred" "struct proc *p"
|
|
.Sh DESCRIPTION
|
|
This entry point checks the access permissions of the file against the
|
|
given credentials.
|
|
.Pp
|
|
Its arguments are:
|
|
.Bl -tag -width mode
|
|
.It Ar vp
|
|
the vnode of the file to check
|
|
.It Ar mode
|
|
the type of access required
|
|
.It Ar cred
|
|
the user credentials to check
|
|
.It Ar p
|
|
the process which is checking
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fa mode
|
|
is a mask which can contain
|
|
.Dv VREAD ,
|
|
.Dv VWRITE or
|
|
.Dv VEXEC.
|
|
.Sh LOCKS
|
|
The vnode should be locked on entry.
|
|
.Sh RETURN VALUES
|
|
If the file is accessable in the specified way, then zero is returned,
|
|
otherwise an appropriate error code is returned.
|
|
.Sh PSEUDOCODE
|
|
.Bd -literal
|
|
int
|
|
vop_access(struct vnode *vp, int mode, struct ucred *cred, struct proc *p)
|
|
{
|
|
int error;
|
|
|
|
/*
|
|
* Disallow write attempts on read-only file systems;
|
|
* unless the file is a socket, fifo, or a block or
|
|
* character device resident on the file system.
|
|
*/
|
|
if (mode & VWRITE) {
|
|
switch (vp->v_type) {
|
|
case VDIR:
|
|
case VLNK:
|
|
case VREG:
|
|
if (vp->v_mount->mnt_flag & MNT_RDONLY)
|
|
return EROFS;
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If immutable bit set, nobody gets to write it. */
|
|
if ((mode & VWRITE) && vp has immutable bit set)
|
|
return EPERM;
|
|
|
|
/* Otherwise, user id 0 always gets access. */
|
|
if (cred->cr_uid == 0)
|
|
return 0;
|
|
|
|
mask = 0;
|
|
|
|
/* Otherwise, check the owner. */
|
|
if (cred->cr_uid == owner of vp) {
|
|
if (mode & VEXEC)
|
|
mask |= S_IXUSR;
|
|
if (mode & VREAD)
|
|
mask |= S_IRUSR;
|
|
if (mode & VWRITE)
|
|
mask |= S_IWUSR;
|
|
return (((mode of vp) & mask) == mask ? 0 : EACCES);
|
|
}
|
|
|
|
/* Otherwise, check the groups. */
|
|
for (i = 0, gp = cred->cr_groups; i < cred->cr_ngroups; i++, gp++)
|
|
if (group of vp == *gp) {
|
|
if (mode & VEXEC)
|
|
mask |= S_IXGRP;
|
|
if (mode & VREAD)
|
|
mask |= S_IRGRP;
|
|
if (mode & VWRITE)
|
|
mask |= S_IWGRP;
|
|
return (((mode of vp) & mask) == mask ? 0 : EACCES);
|
|
}
|
|
|
|
/* Otherwise, check everyone else. */
|
|
if (mode & VEXEC)
|
|
mask |= S_IXOTH;
|
|
if (mode & VREAD)
|
|
mask |= S_IROTH;
|
|
if (mode & VWRITE)
|
|
mask |= S_IWOTH;
|
|
return (((mode of vp) & mask) == mask ? 0 : EACCES);
|
|
}
|
|
.Ed
|
|
.Sh ERRORS
|
|
.Bl -tag -width EACCESS
|
|
.It Bq Er EPERM
|
|
An attempt was made to change an immutable file
|
|
.It Bq Er EACCES
|
|
Permission denied
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr vnode 9
|
|
.Sh AUTHORS
|
|
This man page was written by Doug Rabson.
|