.TH SETLAB 1
.SH NAME
setlab, downgrade, setpriv \- set security label on files
.SH SYNOPSIS
.B setlab
[
.I option ...
]
.I label file ...
]
.PP
.B priv downgrade 
[
.B -v
] 
.I delta file ...
.PP
.B priv setpriv 
.I cap lic file ...
.SH DESCRIPTION
.I Setlab
sets the security label on the named
.I files,
or on the standard input if no files are named.
The
.I label
is a single argument in the style accepted by
.IR atolab ;
see
.IR labtoa (3).
The options are
.TP
.B -a
Add
.I label
to the current file label 
.RI ( new = old | label\fR).
.TP
.B -s
Subtract
.I label
from the current file label
.RI ( new = old &~ label\fR).
.TP
.B -p
Set privileges (capabilities and licenses) only.
.TP
.B -v
Print a blow-by-blow account on standard error file.
.PP
The process must be able to open the file, either for
reading or writing.
One or more licenses (see
.IR getplab (2))
are needed in some instances:
.TF T_SETPRIV
.TP
.B T_EXTERN
to downgrade (new label does not dominate old)
.PD
.TP
.B T_SETPRIV
if either the old or the new label
has nonzero privilege bits
.TP
.BR T_NOCHK 
if the old label has flag
.BR L_NO 
(also need
.B T_EXTERN
to change away from
.BR L_NO ).
.PP
.I Downgrade
uses
.I setlab
to clear the label bits designated by
.IR delta .
It is a conventional request defined in the privilege file,
.IR privs (5),
which checks that the user has authority over the specified
label bits and supplies the necessary privilege to
.I setlab.
.PP
.I Setpriv
is a conventional interface to
.I setlab
for changing file capabilities and licenses.
.PP
.I
.SH EXAMPLES
.TP
.L
setlab ffff... file
Give the file a top label.
.TP
.L
setlab -a F file
Freeze a file label to keep writes from
raising the lattice value.
.TP
.L
lmask x setlab -s 03 file
Downgrade a security label using a privileged
.IR nosh (8)
session.
The 
.I downgrade
priv request is preferred.
.TP
.L
priv downgrade 03 file
Same, using obtaining the necessary authorization and privilege from
.IR priv (1).
.TP
.L
priv setpriv - n file
Give the file a license, but no capabilities.
This is a conventional trick to make the file immutable until
its privileges are turned off again.
The lattice value of the label is bottom (all zero).
.SH DIAGNOSTICS
`Locking file for vetting'.
As a matter of policy,
.I setlab
refuses to assign arbitrary privileges to a previously unprivileged
(`untrusted') file.
Instead it marks the file immutable as in the last example.
The file may then be examined at leisure to assess
whether its contents are indeed trustable before
privileges are finally assigned.
.SH SEE ALSO
.IR getflab (2),
.IR getlab (1),
.IR priv (1)
.SH BUGS
The strings
.B -a
and
.B -p
happen to be legitimate, if unusual, labels.
They will always be understood as option flags.