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Date:      Tue, 19 Nov 2019 12:25:29 -0500 (EST)
From:      Walter Cramer <wfc@mintsol.com>
To:        mike tancsa <mike@sentex.net>
Cc:        Christos Chatzaras <chris@cretaforce.gr>, freebsd-stable <freebsd-stable@freebsd.org>
Subject:   Re: jexec as user?
Message-ID:  <20191119120818.M60603@mulder.mintsol.com>
In-Reply-To: <f78012e9-9de9-8c47-111b-383ce6773ac9@sentex.net>
References:  <1237616943.9.1574163726832@localhost> <a572c2ec-52b6-0999-9106-75051cfc9821@sentex.net> <F75AA78E-EC55-49F8-9CEA-AB6C6F0BD742@cretaforce.gr> <f78012e9-9de9-8c47-111b-383ce6773ac9@sentex.net>

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On Tue, 19 Nov 2019, mike tancsa wrote:
> On 11/19/2019 8:09 AM, Christos Chatzaras wrote:
> On 19 Nov 2019, at 15:02, mike tancsa <mike@sentex.net> wrote:
>> On 11/19/2019 6:42 AM, Ronald Klop wrote:
>>> Hi,
>>>
>>> Is it possible to jexec into a jail as a regular user. Or to enable
>>> that somewhere?
>>> Or is the way to do such a thing to set up ssh in the jail?
>>>
>> On 11.3 at least, does not the built in functionality of jexec do what
>> you need ?
>>
>> jexec [-l] [-u username | -U username] jail [command ...]
>>
>> # jexec -U testuser 3 csh
>> testuser@cacticonsole:/ % id
>> uid=3D1005(testuser) gid=3D1005(testuser) groups=3D1005(testuser)
>> testuser@cacticonsole:/ %
>>
> I think he wants to use jexec as a normal user from the main OS.
>
> If he wants to run jexec as root and login to jail as user then your comm=
and works.

Ahhh, my mistake.=C2=A0 =C2=A0 A sudo entry then ?

=C2=A0=C2=A0=C2=A0 ---Mike

At least on older FreeBSD versions, it's easy to wrap `jexec` in a few=20
lines (literally a half-dozen) of C code, suid after compiling, and have=20
users in the host environment jump into jails with it.  (I haven't set=20
this up in a while, to know if there are issues with 11.X or 12.X.)

OTOH, there is a bitter-regret-filled gap between knowing enough to do=20
that, and knowing enough to securely write and deploy suid-root programs.

-Walter

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Subject: Re: jexec as user?
To: Christos Chatzaras <chris@cretaforce.gr>,
 freebsd-stable <freebsd-stable@freebsd.org>
References: <1237616943.9.1574163726832@localhost>
 <a572c2ec-52b6-0999-9106-75051cfc9821@sentex.net>
 <F75AA78E-EC55-49F8-9CEA-AB6C6F0BD742@cretaforce.gr>
Cc: Ronald Klop <ronald-lists@klop.ws>
From: Miroslav Lachman <000.fbsd@quip.cz>
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Christos Chatzaras wrote on 2019/11/19 14:09:
> 
> 
>> On 19 Nov 2019, at 15:02, mike tancsa <mike@sentex.net> wrote:
>>
>> On 11/19/2019 6:42 AM, Ronald Klop wrote:
>>> Hi,
>>>
>>> Is it possible to jexec into a jail as a regular user. Or to enable
>>> that somewhere?
>>> Or is the way to do such a thing to set up ssh in the jail?
>>>
>> On 11.3 at least, does not the built in functionality of jexec do what
>> you need ?
>>
>> jexec [-l] [-u username | -U username] jail [command ...]
>>
>> # jexec -U testuser 3 csh
>> testuser@cacticonsole:/ % id
>> uid=1005(testuser) gid=1005(testuser) groups=1005(testuser)
>> testuser@cacticonsole:/ %
>>
> 
> I think he wants to use jexec as a normal user from the main OS.
> 
> If he wants to run jexec as root and login to jail as user then your command works.

If you want to use jexec as normal user in host, look at sysutils/jailme 
from ports:

https://www.freshports.org/sysutils/jailme/
This version is installed setuid and does some sanity checking to ensure 
the username and UID match between the jail and the host system.

WWW: https://github.com/Intermedix/jailme

Miroslav Lachman

PS: I never used jailme personally



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