1f305be431
PR: 248335 Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D25886
306 lines
7.3 KiB
Groff
306 lines
7.3 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993, 1994
|
|
.\" The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
|
|
.\"
|
|
.\" @(#)chown.2 8.4 (Berkeley) 4/19/94
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 23, 2020
|
|
.Dt CHOWN 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm chown ,
|
|
.Nm fchown ,
|
|
.Nm lchown ,
|
|
.Nm fchownat
|
|
.Nd change owner and group of a file
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft int
|
|
.Fn chown "const char *path" "uid_t owner" "gid_t group"
|
|
.Ft int
|
|
.Fn fchown "int fd" "uid_t owner" "gid_t group"
|
|
.Ft int
|
|
.Fn lchown "const char *path" "uid_t owner" "gid_t group"
|
|
.Ft int
|
|
.Fn fchownat "int fd" "const char *path" "uid_t owner" "gid_t group" "int flag"
|
|
.Sh DESCRIPTION
|
|
The owner ID and group ID of the file
|
|
named by
|
|
.Fa path
|
|
or referenced by
|
|
.Fa fd
|
|
is changed as specified by the arguments
|
|
.Fa owner
|
|
and
|
|
.Fa group .
|
|
The owner of a file may change the
|
|
.Fa group
|
|
to a group of which
|
|
he or she is a member,
|
|
but the change
|
|
.Fa owner
|
|
capability is restricted to the super-user.
|
|
.Pp
|
|
The
|
|
.Fn chown
|
|
system call
|
|
clears the set-user-id and set-group-id bits
|
|
on the file
|
|
to prevent accidental or mischievous creation of
|
|
set-user-id and set-group-id programs if not executed
|
|
by the super-user.
|
|
The
|
|
.Fn chown
|
|
system call
|
|
follows symbolic links to operate on the target of the link
|
|
rather than the link itself.
|
|
.Pp
|
|
The
|
|
.Fn fchown
|
|
system call
|
|
is particularly useful when used in conjunction
|
|
with the file locking primitives (see
|
|
.Xr flock 2 ) .
|
|
.Pp
|
|
The
|
|
.Fn lchown
|
|
system call is similar to
|
|
.Fn chown
|
|
but does not follow symbolic links.
|
|
.Pp
|
|
The
|
|
.Fn fchownat
|
|
system call is equivalent to the
|
|
.Fn chown
|
|
and
|
|
.Fn lchown
|
|
except in the case where
|
|
.Fa path
|
|
specifies a relative path.
|
|
In this case the file to be changed is determined relative to the directory
|
|
associated with the file descriptor
|
|
.Fa fd
|
|
instead of the current working directory.
|
|
.Pp
|
|
Values for
|
|
.Fa flag
|
|
are constructed by a bitwise-inclusive OR of flags from the following
|
|
list, defined in
|
|
.In fcntl.h :
|
|
.Bl -tag -width indent
|
|
.It Dv AT_SYMLINK_NOFOLLOW
|
|
If
|
|
.Fa path
|
|
names a symbolic link, ownership of the symbolic link is changed.
|
|
.It Dv AT_BENEATH
|
|
Only allow to change ownership of a file which is beneath of
|
|
the topping directory.
|
|
See the description of the
|
|
.Dv O_BENEATH
|
|
flag in the
|
|
.Xr open 2
|
|
manual page.
|
|
.It Dv AT_RESOLVE_BENEATH
|
|
Only walks paths below the topping directory.
|
|
See the description of the
|
|
.Dv O_RESOLVE_BENEATH
|
|
flag in the
|
|
.Xr open 2
|
|
manual page.
|
|
.El
|
|
.Pp
|
|
If
|
|
.Fn fchownat
|
|
is passed the special value
|
|
.Dv AT_FDCWD
|
|
in the
|
|
.Fa fd
|
|
parameter, the current working directory is used and the behavior is identical
|
|
to a call to
|
|
.Fn chown
|
|
or
|
|
.Fn lchown
|
|
respectively, depending on whether or not the
|
|
.Dv AT_SYMLINK_NOFOLLOW
|
|
bit is set in the
|
|
.Fa flag
|
|
argument.
|
|
.Pp
|
|
One of the owner or group id's
|
|
may be left unchanged by specifying it as -1.
|
|
.Sh RETURN VALUES
|
|
.Rv -std
|
|
.Sh ERRORS
|
|
The
|
|
.Fn chown
|
|
and
|
|
.Fn lchown
|
|
will fail and the file will be unchanged if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOTDIR
|
|
A component of the path prefix is not a directory.
|
|
.It Bq Er ENAMETOOLONG
|
|
A component of a pathname exceeded 255 characters,
|
|
or an entire path name exceeded 1023 characters.
|
|
.It Bq Er ENOENT
|
|
The named file does not exist.
|
|
.It Bq Er EACCES
|
|
Search permission is denied for a component of the path prefix.
|
|
.It Bq Er ELOOP
|
|
Too many symbolic links were encountered in translating the pathname.
|
|
.It Bq Er EPERM
|
|
The operation would change the ownership, but the effective user ID is not the
|
|
super-user.
|
|
.It Bq Er EPERM
|
|
The named file has its immutable or append-only flag set, see the
|
|
.Xr chflags 2
|
|
manual page for more information.
|
|
.It Bq Er EROFS
|
|
The named file resides on a read-only file system.
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa path
|
|
argument
|
|
points outside the process's allocated address space.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to the file system.
|
|
.It Bq Er EINTEGRITY
|
|
Corrupted data was detected while reading from the file system.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn fchown
|
|
system call will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa fd
|
|
argument
|
|
does not refer to a valid descriptor.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa fd
|
|
argument
|
|
refers to a socket, not a file.
|
|
.It Bq Er EPERM
|
|
The effective user ID is not the super-user.
|
|
.It Bq Er EROFS
|
|
The named file resides on a read-only file system.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to the file system.
|
|
.It Bq Er EINTEGRITY
|
|
Corrupted data was detected while reading from the file system.
|
|
.El
|
|
.Pp
|
|
In addition to the errors specified for
|
|
.Fn chown
|
|
and
|
|
.Fn lchown ,
|
|
the
|
|
.Fn fchownat
|
|
system call may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa path
|
|
argument does not specify an absolute path and the
|
|
.Fa fd
|
|
argument is neither
|
|
.Dv AT_FDCWD
|
|
nor a valid file descriptor open for searching.
|
|
.It Bq Er EINVAL
|
|
The value of the
|
|
.Fa flag
|
|
argument is not valid.
|
|
.It Bq Er ENOTDIR
|
|
The
|
|
.Fa path
|
|
argument is not an absolute path and
|
|
.Fa fd
|
|
is neither
|
|
.Dv AT_FDCWD
|
|
nor a file descriptor associated with a directory.
|
|
.It Bq Er ENOTCAPABLE
|
|
.Fa path
|
|
is an absolute path,
|
|
or contained a ".." component leading to a
|
|
directory outside of the directory hierarchy specified by
|
|
.Fa fd ,
|
|
and the process is in capability mode.
|
|
.It Bq Er ENOTCAPABLE
|
|
The
|
|
.Dv AT_BENEATH
|
|
flag was provided to
|
|
.Fn fchownat ,
|
|
and the absolute
|
|
.Fa path
|
|
does not have its tail fully contained under the topping directory,
|
|
or the relative
|
|
.Fa path
|
|
escapes it.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr chgrp 1 ,
|
|
.Xr chflags 2 ,
|
|
.Xr chmod 2 ,
|
|
.Xr flock 2 ,
|
|
.Xr chown 8
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn chown
|
|
system call is expected to conform to
|
|
.St -p1003.1-90 .
|
|
The
|
|
.Fn fchownat
|
|
system call follows The Open Group Extended API Set 2 specification.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn chown
|
|
function appeared in
|
|
.At v1 .
|
|
The
|
|
.Fn fchown
|
|
system call appeared in
|
|
.Bx 4.2 .
|
|
.Pp
|
|
The
|
|
.Fn chown
|
|
system call was changed to follow symbolic links in
|
|
.Bx 4.4 .
|
|
The
|
|
.Fn lchown
|
|
system call was added in
|
|
.Fx 3.0
|
|
to compensate for the loss of functionality.
|
|
.Pp
|
|
The
|
|
.Fn fchownat
|
|
system call appeared in
|
|
.Fx 8.0 .
|