210 lines
6.3 KiB
Groff
210 lines
6.3 KiB
Groff
.\"-
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.\" Copyright (c) 1999-2001 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 December 23, 1999
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.Os
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.Dt ACL 9
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.Sh NAME
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.Nm acl
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.Nd virtual file system access control lists
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/vnode.h
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.In sys/acl.h
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.Pp
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In the kernel configuration file:
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.Cd "options UFS_ACL"
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.Sh DESCRIPTION
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Access control lists, or ACLs,
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allow fine-grained specification of rights
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for vnodes representing files and directories.
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However, as there are a plethora of file systems with differing ACL semantics,
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the vnode interface is aware only of the syntax of ACLs,
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relying on the underlying file system to implement the details.
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Depending on the underlying file system, each file or directory
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may have zero or more ACLs associated with it, named using the
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.Fa type
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field of the appropriate vnode ACL calls:
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.Xr VOP_ACLCHECK 9 ,
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.Xr VOP_GETACL 9 ,
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and
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.Xr VOP_SETACL 9 .
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.Pp
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Currently, each ACL is represented in-kernel by a fixed-size
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.Vt acl
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structure, defined as follows:
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.Bd -literal -offset indent
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struct acl {
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int acl_cnt;
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struct acl_entry acl_entry[ACL_MAX_ENTRIES];
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};
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.Ed
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.Pp
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An ACL is constructed from a fixed size array of ACL entries,
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each of which consists of a set of permissions, principal namespace,
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and principal identifier.
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.Pp
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Each individual ACL entry is of the type
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.Vt acl_entry_t ,
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which is a structure with the following members:
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.Bl -tag -width 2n
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.It Vt acl_tag_t Va ae_tag
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The following is a list of definitions of ACL types
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to be set in
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.Va ae_tag :
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.Pp
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.Bl -tag -width ".Dv ACL_UNDEFINED_FIELD" -offset indent -compact
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.It Dv ACL_UNDEFINED_FIELD
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Undefined ACL type.
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.It Dv ACL_USER_OBJ
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Discretionary access rights for processes whose effective user ID
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matches the user ID of the file's owner.
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.It Dv ACL_USER
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Discretionary access rights for processes whose effective user ID
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matches the ACL entry qualifier.
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.It Dv ACL_GROUP_OBJ
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Discretionary access rights for processes whose effective group ID
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or any supplemental groups
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match the group ID of the file's owner.
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.It Dv ACL_GROUP
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Discretionary access rights for processes whose effective group ID
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or any supplemental groups
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match the ACL entry qualifier.
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.It Dv ACL_MASK
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The maximum discretionary access rights that can be granted
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to a process in the file group class.
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.It Dv ACL_OTHER
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Discretionary access rights for processes not covered by any other ACL
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entry.
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.It Dv ACL_OTHER_OBJ
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Same as
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.Dv ACL_OTHER .
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Each ACL entry must contain exactly one
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.Dv ACL_USER_OBJ ,
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one
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.Dv ACL_GROUP_OBJ ,
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and one
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.Dv ACL_OTHER .
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If any of
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.Dv ACL_USER ,
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.Dv ACL_GROUP ,
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or
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.Dv ACL_OTHER
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are present, then exactly one
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.Dv ACL_MASK
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entry should be present.
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.El
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.It Vt uid_t Va ae_id
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The ID of user for whom this ACL describes access permissions.
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.It Vt acl_perm_t Va ae_perm
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This field defines what kind of access the process matching this ACL has
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for accessing the associated file.
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.Bl -tag -width ".Dv ACL_POSIX1E_BITS"
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.It Dv ACL_EXECUTE
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The process may execute the associated file.
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.It Dv ACL_WRITE
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The process may write to the associated file.
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.It Dv ACL_READ
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The process may read from the associated file.
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.It Dv ACL_PERM_NONE
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The process has no read, write or execute permissions
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to the associated file.
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.El
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.El
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.Pp
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.Sh IMPLEMENTATION NOTES
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.Bd -literal
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typedef mode_t *acl_permset_t;
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/* internal ACL structure */
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struct acl {
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int acl_cnt;
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struct acl_entry acl_entry[ACL_MAX_ENTRIES];
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};
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/* external ACL structure */
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struct acl_t_struct {
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struct acl ats_acl;
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int ats_cur_entry;
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};
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typedef struct acl_t_struct *acl_t;
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/*
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* Possible valid values for ae_tag field.
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*/
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#define ACL_UNDEFINED_TAG 0x00000000
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#define ACL_USER_OBJ 0x00000001
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#define ACL_USER 0x00000002
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#define ACL_GROUP_OBJ 0x00000004
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#define ACL_GROUP 0x00000008
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#define ACL_MASK 0x00000010
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#define ACL_OTHER 0x00000020
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#define ACL_OTHER_OBJ ACL_OTHER
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/*
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* Possible valid values for acl_type_t arguments.
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*/
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#define ACL_TYPE_ACCESS 0x00000000
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#define ACL_TYPE_DEFAULT 0x00000001
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#define ACL_TYPE_AFS 0x00000002
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#define ACL_TYPE_CODA 0x00000003
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#define ACL_TYPE_NTFS 0x00000004
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#define ACL_TYPE_NWFS 0x00000005
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/*
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* Possible flags in ae_perm field.
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*/
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#define ACL_EXECUTE 0x0001
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#define ACL_WRITE 0x0002
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#define ACL_READ 0x0004
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#define ACL_PERM_NONE 0x0000
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#define ACL_PERM_BITS (ACL_EXECUTE | ACL_WRITE | ACL_READ)
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#define ACL_POSIX1E_BITS (ACL_EXECUTE | ACL_WRITE | ACL_READ)
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/*
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* Possible entry_id values for acl_get_entry()
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*/
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#define ACL_FIRST_ENTRY 0
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#define ACL_NEXT_ENTRY 1
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/*
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* Undefined value in ae_id field
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*/
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#define ACL_UNDEFINED_ID ((uid_t)-1)
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.Ed
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.Sh SEE ALSO
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.Xr acl 3 ,
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.Xr vaccess_acl_posix1e 9 ,
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.Xr VFS 9 ,
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.Xr vnaccess 9 ,
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.Xr VOP_ACLCHECK 9 ,
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.Xr VOP_GETACL 9 ,
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.Xr VOP_SETACL 9
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.Sh AUTHORS
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This manual page was written by
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.An Robert Watson .
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