9 Jan
2014
9 Jan
'14
8:48 p.m.
Dos this mean that on some implementations of UNIX, that the chown(2) was usable by
non-root processes??? Maybe I misremembered but I thought that that would fail - even the
chown(1) would fail - if the invoking process (or shell in the case of chown(1)) was not
superuser. If it was allowed to change owners, surely it wouldn't allow one to chown
to root. (Sorry about calling you Surely.)
aps.
Begin forwarded message:
From: Clem Cole <clemc(a)ccc.com>
Subject: Re: [TUHS] History of chown semantics
Date: January 9, 2014 10:48:04 AM PST
To: Ron Natalie <ron(a)ronnatalie.com>
Cc: TUHS main list <tuhs(a)minnie.tuhs.org>
Right ... tools like tar(1) called the system call directly,
Which is why the restriction/check in the research family was done in the OS.
The PWB kernel did not make the check - although V6 did:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/sys/ken/sys4.c
chown()
{
register *ip;
if (
!suser()
|| (ip = owner()) == NULL)
return;
ip->i_uid = u.u_arg[1].lobyte;
ip->i_gid = u.u_arg[1].hibyte;
ip->i_flag =| IUPD;
iput(ip);
}
Where as: PWB 1.0:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/sys/os/sys4.c
chown()
{
register *ip;
if ((ip = owner()) == NULL)
return;
ip->i_uid = u.u_arg[1].lobyte;
ip->i_gid = u.u_arg[1].hibyte;
if(u.u_uid != 0)
ip->i_mode =& ~(ISUID|ISGID);
ip->i_flag =| IUPD;
iput(ip);
}
Clem
On Thu, Jan 9, 2014 at 1:31 PM, Ron Natalie <ron(a)ronnatalie.com> wrote:
There's no real point in restricting the chown program if the system call
remains executable by non-root.
-----Original Message-----
From: tuhs-bounces(a)minnie.tuhs.org [mailto:tuhs-bounces@minnie.tuhs.org] On
Behalf Of Dario Niedermann
Sent: Thursday, January 9, 2014 1:18 PM
To: tuhs(a)minnie.tuhs.org
Subject: Re: [TUHS] History of chown semantics
Il 09/01/2014 alle 15:56, Clem Cole ha scritto:
I agree with you, I always thought it was crazy
[...]
Maybe I'm missing something, but it seems easy enough to make the `chown'
program only executable by root.
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