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eb94f24fab
Mention cr_bsd_visible(9). Remove references to cr_canseeothergids(9) and cr_canseeotheruids(9), as well as indirect references not immediately useful. Fix description of credentials checks to match reality. Re-order errors to match code's check order. Reviewed by: bcr, pauamma_gundo.com MFC after: 2 weeks Sponsored by: Kumacom SAS Differential Revision: https://reviews.freebsd.org/D40638
146 lines
3.7 KiB
Groff
146 lines
3.7 KiB
Groff
.\"
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.\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
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.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr>
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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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 DEVELOPERS ``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 DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 18, 2023
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.Dt P_CANDEBUG 9
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.Os
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.Sh NAME
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.Nm p_candebug
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.Nd determine debuggability of a process
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/proc.h
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.Ft int
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.Fn p_candebug "struct thread *td" "struct proc *p"
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.Sh DESCRIPTION
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This function determines if a given process
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.Fa p
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is debuggable by some thread
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.Fa td .
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.Pp
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The following
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.Xr sysctl 8
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variables directly influence the behaviour of
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.Fn p_candebug :
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.Bl -tag -width indent
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.It Va security.bsd.unprivileged_proc_debug
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Must be set to a non-zero value to allow unprivileged processes
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access to the kernel's debug facilities.
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.It Va kern.securelevel
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Debugging of the init process is not allowed if this variable is
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.Li 1
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or greater.
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.El
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.Pp
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Other such variables indirectly influence it; see
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.Xr cr_bsd_visible 9 .
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.Sh RETURN VALUES
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The
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.Fn p_candebug
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function
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returns
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.Li 0
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if the process denoted by
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.Fa p
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is debuggable by thread
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.Fa td ,
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or a non-zero error return value otherwise.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EPERM
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An unprivileged process attempted to debug another process but the system is
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configured to deny it
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.Po
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see
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.Xr sysctl 8
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variable
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.Va security.bsd.unprivileged_proc_debug
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above
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.Pc .
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.It Bq Er ESRCH
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Thread
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.Fa td
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has been jailed and the process to debug does not belong to the same jail or one
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of its sub-jails, as determined by
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.Xr prison_check 9 .
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.It Bq Er ESRCH
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.Xr cr_bsd_visible 9
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denied visibility according to the BSD security policies in force.
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.It Bq Er EPERM
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Thread
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.Fa td
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lacks superuser credentials and its (effective) group set is not a superset of
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process
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.Fa p Ns 's
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whole group set
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.Pq "including real, effective and saved group IDs" .
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.It Bq Er EPERM
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Thread
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.Fa td
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lacks superuser credentials and its (effective) user ID does not match all user
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IDs of process
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.Fa p .
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.It Bq Er EPERM
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Thread
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.Fa td
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lacks superuser credentials and process
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.Fa p
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is executing a set-user-ID or set-group-ID executable.
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.It Bq Er EPERM
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Process
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.Fa p
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denotes the initial process
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.Fn initproc
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and the
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.Xr sysctl 8
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variable
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.Va kern.securelevel
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is greater than zero.
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.It Bq Er EBUSY
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Process
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.Fa p
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is in the process of being
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.Fn exec Ns 'ed.
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.It Bq Er EPERM
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Process
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.Fa p
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denied debuggability
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.Po
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see
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.Xr procctl 2 ,
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command
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.Dv PROC_TRACE_CTL
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.Pc .
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.El
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.Sh SEE ALSO
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.Xr prison_check 9 ,
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.Xr mac 9 ,
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.Xr cr_bsd_visible 9 ,
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.Xr procctl 2 ,
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.Xr p_cansee 9
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