30c4fc7cf9
Document the need for the setuid bit and how to set it. Explain why it isn't set by default, and suggest simply adding users to groups instead. PR: docs/167741 MFC after: 3 weeks
105 lines
3.0 KiB
Groff
105 lines
3.0 KiB
Groff
.\" Copyright (c) 2002 Tim J. Robbins.
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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 February 8, 2013
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.Dt NEWGRP 1
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.Os
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.Sh NAME
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.Nm newgrp
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.Nd change to a new group
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.Sh SYNOPSIS
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.Nm
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.Op Fl l
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.Op Ar group
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.Sh DESCRIPTION
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The
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.Nm
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utility creates a new shell execution environment with modified
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real and effective group IDs.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl l
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Simulate a full login.
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The environment and umask are set to what would be expected if the user
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actually logged in again.
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.El
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.Pp
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If the
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.Ar group
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operand is present, a new shell is started with the specified effective
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and real group IDs.
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The user will be prompted for a password if they are not a member of the
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specified group.
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.Pp
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Otherwise, the real, effective and supplementary group IDs are restored to
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those from the current user's password database entry.
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.Sh EXIT STATUS
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The
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.Nm
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utility attempts to start the shell regardless of whether group IDs
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were successfully changed.
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.Pp
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If an error occurs and the shell cannot be started,
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.Nm
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exits >0.
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Otherwise, the exit status of
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.Nm
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is the exit status of the shell.
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.Sh SEE ALSO
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.Xr csh 1 ,
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.Xr groups 1 ,
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.Xr login 1 ,
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.Xr sh 1 ,
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.Xr su 1 ,
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.Xr umask 1 ,
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.Xr group 5 ,
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.Xr passwd 5 ,
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.Xr environ 7
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.Sh STANDARDS
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The
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.Nm
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utility conforms to
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.St -p1003.1-2001 .
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v6 .
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.Sh BUGS
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For security reasons, the
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.Nm
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utility is normally installed without the setuid bit.
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To enable it, run the following command:
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.Bd -literal -offset indent
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chmod u+s /usr/bin/newgrp
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.Ed
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.Pp
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Group passwords are inherently insecure as there is no way to stop
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users obtaining the password hash from the group database.
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Their use is discouraged.
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Instead, users should simply be added to the necessary groups.
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