freebsd-skq/bin/setfacl/setfacl.1
Robert Watson ea03990629 Add additional documentation to setfacl(1) regarding the behavior of
tools such as chmod(1) and ls(1) when it comes to acting on objects
that have POSIX.1e extended ACLs.  Specifically, discuss the
substitution of the mask entry for the group entry in the mode
representation of the ACL.  Differently worded from the submission,
and could probably use further refinement.

PR:		55319
Submitted by:	Grzegorz Czaplinski <G.Czaplinski@prioris.mini.pw.edu.pl>
2003-08-07 14:52:17 +00:00

286 lines
7.4 KiB
Groff

.\"
.\" Copyright (c) 2001 Chris D. Faulhaber
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.\" $FreeBSD$
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.Dd January 7, 2001
.Dt SETFACL 1
.Os
.Sh NAME
.Nm setfacl
.Nd set ACL information
.Sh SYNOPSIS
.Nm
.Op Fl bdhkn
.Op Fl m Ar entries
.Op Fl M Ar file1
.Op Fl x Ar entries
.Op Fl X Ar file1
.Op Ar
.Sh DESCRIPTION
The
.Nm
utility sets discretionary access control information on
the specified file(s).
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl b
Remove all ACL entries except for the three required entries.
If the ACL contains a
.Dq Li mask
entry, the permissions of the
.Dq Li group
entry in the resulting ACL will be set to the permission
associated with both the
.Dq Li group
and
.Dq Li mask
entries of the current ACL.
.It Fl d
The operations apply to the default ACL entries instead of
access ACL entries. Currently only directories may have
default ACL's.
.It Fl h
If the target of the operation is a symbolic link, perform the operation
on the symbolic link itself, rather than following the link.
.It Fl k
Delete any default ACL entries on the specified files. It
is not considered an error if the specified files do not have
any default ACL entries. An error will be reported if any of
the specified files cannot have a default entry (i.e.\&
non-directories).
.It Fl m Ar entries
Modify the ACL entries on the specified files by adding new
entries and modifying existing ACL entries with the ACL entries
specified in
.Ar entries .
.It Fl M Ar file
Modify the ACL entries on the specified files by adding new
ACL entries and modifying existing ACL entries with the ACL
entries specified in the file
.Ar file .
If
.Ar file
is
.Fl ,
the input is taken from stdin.
.It Fl n
Do not recalculate the permissions associated with the ACL
mask entry.
.It Fl x Ar entries
Remove the ACL entries specified in
.Ar entries
from the access or default ACL of the specified files.
.It Fl X Ar file
Remove the ACL entries specified in the file
.Ar file
from the access or default ACL of the specified files.
.El
.Pp
The above options are evaluated in the order specified
on the command-line.
.Sh ACL ENTRIES
An ACL entry contains three colon-separated fields:
an ACL tag, an ACL qualifier, and discretionary access
permissions:
.Bl -tag -width indent
.It Ar "ACL tag"
The ACL tag specifies the ACL entry type and consists of
one of the following:
.Dq Li user
or
.Ql u
specifying the access
granted to the owner of the file or a specified user;
.Dq Li group
or
.Ql g
specifying the access granted to the file owning group
or a specified group;
.Dq Li other
or
.Ql o
specifying the access
granted to any process that does not match any user or group
ACL entry;
.Dq Li mask
or
.Ql m
specifying the maximum access
granted to any ACL entry except the
.Dq Li user
ACL entry for the file owner and the
.Dq Li other
ACL entry.
.It Ar "ACL qualifier"
The ACL qualifier field describes the user or group associated with
the ACL entry. It may consist of one of the following: uid or
user name, gid or group name, or empty. For
.Dq Li user
ACL entries, an empty field specifies access granted to the
file owner. For
.Dq Li group
ACL entries, an empty field specifies access granted to the
file owning group.
.Dq Li mask
and
.Dq Li other
ACL entries do not use this field.
.It Ar "access permissions"
The access permissions field contains up to one of each of
the following:
.Ql r ,
.Ql w ,
and
.Ql x
to set read, write, and
execute permissions, respectively. Each of these may be excluded
or replaced with a
.Ql -
character to indicate no access.
.El
.Pp
A
.Dq Li mask
ACL entry is required on a file with any ACL entries other than
the default
.Dq Li user ,
.Dq Li group ,
and
.Dq Li other
ACL entries. If the
.Fl n
option is not specified and no
.Dq Li mask
ACL entry was specified, the
.Nm
utility
will apply a
.Dq Li mask
ACL entry consisting of the union of the permissions associated
with all
.Dq Li group
ACL entries in the resulting ACL.
.Pp
Traditional POSIX interfaces acting on file system object modes have
modified semantics in the presence of POSIX.1e extended ACLs.
When a mask entry is present on the access ACL of an object, the mask
entry is substituted for the group bits; this occurs in programs such
as
.Xr stat 1
or
.Xr ls 1 .
When the mode is modified on an object that has a mask entry, the
changes applied to the group bits will actually be applied to the
mask entry.
These semantics provide for greater application compatibility:
applications modifying the mode instead of the ACL will see
conservative behavior, limiting the effective rights granted by all
of the additional user and group entries; this occurs in programs
such as
.Xr chmod 1 .
.Pp
ACL entries applied from a file using the
.Fl M
or
.Fl X
options shall be of the following form: one ACL entry per line, as
previously specified; whitespace is ignored; any text after a
.Ql #
is ignored (comments).
.Pp
When ACL entries are evaluated, the access check algorithm checks
the ACL entries in the following order: file owner,
.Dq Li user
ACL entries, file owning group,
.Dq Li group
ACL entries, and
.Dq Li other
ACL entry.
.Pp
Multiple ACL entries specified on the command line are
separated by commas.
.Sh DIAGNOSTICS
.Ex -std
.Sh EXAMPLES
.Dl setfacl -m u::rwx,g:mail:rw file
.Pp
Sets read, write, and execute permissions for the
.Pa file
owner's ACL entry and read and write permissions for group mail on
.Pa file .
.Pp
.Dl setfacl -M file1 file2
.Pp
Sets/updates the ACL entries contained in
.Pa file1
on
.Pa file2 .
.Pp
.Dl setfacl -x g:mail:rw file
.Pp
Remove the group mail ACL entry containing read/write permissions
from
.Pa file.
.Pp
.Dl setfacl -bn file
.Pp
Remove all
.Dq Li access
ACL entries except for the three required from
.Pa file .
.Pp
.Dl getfacl file1 | setfacl -b -n -M - file2
.Pp
Copy ACL entries from
.Pa file1
to
.Pa file2 .
.Sh SEE ALSO
.Xr getfacl 1 ,
.Xr acl 3 ,
.Xr getextattr 8 ,
.Xr setextattr 8 ,
.Xr acl 9 ,
.Xr extattr 9
.Sh STANDARDS
The
.Nm
utility is expected to be
.Tn IEEE
Std 1003.2c compliant.
.Sh HISTORY
Extended Attribute and Access Control List support was developed
as part of the
.Tn TrustedBSD
Project and introduced in
.Fx 5.0 .
.Sh AUTHORS
The
.Nm
utility was written by
.An Chris D. Faulhaber Aq jedgar@fxp.org .