114 lines
3.5 KiB
Groff
114 lines
3.5 KiB
Groff
.\"
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.\" Copyright (c) 1996 Julian R Elischer
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed by Kenneth Stailey.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed for the FreeBSD Project
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.\" by Julian R Elischer
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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.\" 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 April 2, 2002
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.Dt SUSER 9
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.Os
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.Sh NAME
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.Nm suser ,
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.Nm suser_cred
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.Nd check if credentials have superuser privilege
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/systm.h
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.Ft int
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.Fn suser "struct thread *td"
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.Ft int
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.Fn suser_cred "struct ucred *cred" "int flag"
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.Sh DESCRIPTION
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The
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.Fn suser
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and
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.Fn suser_cred
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functions check if the credentials given include superuser powers.
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.Pp
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The
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.Fn suser
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function is the most common, and should be used unless special
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circumstances dictate otherwise.
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.Pp
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The
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.Fn suser_cred
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function should be used when the credentials to be checked are
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not the thread's own, when there is no thread, or when superuser
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powers should be extended to imprisoned roots.
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.Pp
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By default, a process does not command superuser powers if it has
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been imprisoned by the
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.Xr jail 2
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system call.
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There are cases however where this is appropriate, and this can
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be done by passing
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.Dv PRISON_ROOT
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in the
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.Fa flag
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argument to the
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.Fn suser_cred
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function.
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It is important to review carefully in each case that
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this does not weaken the prison.
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Generally, only where the action is protected by
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.Xr chroot 2
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implicit in the
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.Xr jail 2
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call should such powers be granted.
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.Pp
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The
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.Fn suser
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and
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.Fn suser_cred
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functions note the fact that superuser powers have been used in the
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process structure of the process specified.
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Because part of their function is to notice
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whether superuser powers have been used,
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the functions should only be called after other permission
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possibilities have been exhausted.
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.Sh RETURN VALUES
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The
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.Fn suser
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and
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.Fn suser_cred
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functions return 0 if the user has superuser powers and
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.Er EPERM
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otherwise.
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This is the
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.Em reverse logic
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of some other implementations of
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.Fn suser
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in which a TRUE response indicates superuser powers.
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.Sh SEE ALSO
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.Xr chroot 2 ,
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.Xr jail 2
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