183 lines
6.2 KiB
Groff
183 lines
6.2 KiB
Groff
.\"-
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.\" Copyright (c) 2000 Robert N. M. Watson
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 28, 2000
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.Dt ACL 3
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.Os FreeBSD 4.0
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.Sh NAME
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.Nm acl
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.Nd introduction to the POSIX.1e ACL security API
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.Sh LIBRARY
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.Lb libposix1e
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/acl.h>
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.Sh DESCRIPTION
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As shipped,
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.Fx 4.0
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permits file systems to export
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Access Control Lists via the VFS, and provides a library for userland
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access to and manipulation of these ACLs, but support for ACLs is not
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provided by any file systems shipped in the base operating system.
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The library calls shipped with 4.0 include routines to allocate,
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duplicate, retrieve, set, and validate ACLs associated with file objects.
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As well as the POSIX.1e routines, there are a number of non-portable
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extensions defined that allow for alternative ACL semantics than the
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POSIX.1e semantics, such as AFS, NTFS, Coda, and NWFS semantics. Where
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routines are non-standard, they are suffixed with _np to indicate that
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they are not portable.
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POSIX.1e describes a set of ACL manipulation routines to manage the
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contents of ACLs, as well as their relationships with files. This
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manipulation library is not currently implemented in FreeBSD, although
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a third party library was under development at the time this document
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was written. There is a general consensus that the POSIX.1e manipulation
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routines are ambiguously defined in the specification, and don't meet the
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needs of most applications. For the time being, applications may
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directly manipulate the ACL structures, defined in acl.h, although the
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recommended usage is to only ever handle text-form ACLs in applications,
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generated and maintained using
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.Fn acl_from_text
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and
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.Fn acl_to_text ,
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passed directly to and from the management routines. In this manner,
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an application can remain safely unaware of the contents of ACLs.
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Available functions, sorted by behavior, include:
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.Fn acl_delete_def_file ,
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.Fn acl_delete_file_np ,
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.Fn acl_delete_fd_np
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These functions are described in
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.Xr acl_delete 3 ,
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and may be used to delete ACLs from file system objects.
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.Fn acl_free
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This function is described in
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.Xr acl_free 3 ,
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and may be used to free userland working ACL storage.
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.Fn acl_from_text
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This function is described in
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.Xr acl_from_text 3 ,
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and may be used to convert a text-form ACL into working ACL state, if
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the ACL has POSIX.1e semantics.
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.Fn acl_get_file ,
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.Fn acl_get_fd ,
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.Fn acl_get_fd_np
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These functions are described in
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.Xr acl_get 3 ,
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and may be used to retrieve ACLs from file system objects.
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.Fn acl_init
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This function is described in
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.Xr acl_init 3 ,
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and may be used to allocate a fresh (empty) ACL structure.
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.Fn acl_dup
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This function is described in
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.Xr acl_dup 3 ,
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and may be used to duplicate an ACL structure.
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.Fn acl_set_file ,
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.Fn acl_set_fd ,
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.Fn acl_set_fd_np
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These functions are described in
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.Xr acl_set 3 ,
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and may be used to assign an ACL to a file system object.
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.Fn acl_to_text
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This function is described in
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.Xr acl_to_text 3 ,
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and may be used to generate a text-form of a POSIX.1e semantics ACL.
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.Fn acl_valid ,
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.Fn acl_valid_file_np ,
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.Fn acl_valid_fd_np
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Thee functions are described in
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.Xr acl_valid 3 ,
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and may be used to validate an ACL as correct POSIX.1e-semantics, or
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as appropriate for a particular file system object regardless of semantics.
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Documentation of the internal kernel interfaces backing these calls may
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be found in
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.Xr acl 9 .
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The syscalls between the internal interfaces and the public library
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routines may change over time, and as such are not documented. They are
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not intended to be called directly without going through the library.
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.Sh IMPLEMENTATION NOTES
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FreeBSD's support for POSIX.1e interfaces and features is still under
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development at this time.
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.Sh ENVIRONMENT
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POSIX.1e assigns security labels to all objects, extending the security
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functionality described in POSIX.1. These additional labels provide
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fine-grained discretionary access control, fine-grained capabilities,
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and labels necessary for mandatory access control. POSIX.2c describes
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a set of userland utilities for manipulating these labels. These userland
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utilities are not bundled with
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.Fx 4.0
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so as to discourage their
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use in the short term.
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.\" .Sh FILES
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.Sh SEE ALSO
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.Xr acl 3 ,
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.Xr acl_dup 3 ,
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.Xr acl_free 3 ,
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.Xr acl_from_text 3 ,
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.Xr acl_get 3 ,
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.Xr acl_set 3 ,
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.Xr acl_to_text 3 ,
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.Xr acl_valid 3 ,
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.Xr acl 9
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.Sh STANDARDS
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POSIX.1e is described in IEEE POSIX.1e draft 17. Discussion
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of the draft continues on the cross-platform POSIX.1e implementation
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mailing list. To join this list, see the
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.Fx
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POSIX.1e implementation
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page for more information.
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.Sh HISTORY
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POSIX.1e support was introduced in
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.Fx 4.0 ,
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and development continues.
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.Sh AUTHORS
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.An Robert N M Watson
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.Sh BUGS
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These features are not yet fully implemented. In particular, the shipped
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version of UFS/FFS does not support storage of additional security labels,
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and so is unable to (easily) provide support for most of these features.
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