Subject: Re: LKM's shouldn't be allowed to be loaded in multiuser mode.
To: None <email@example.com.OZ.AU>
From: Kenneth Stailey <firstname.lastname@example.org>
Date: 03/20/1995 19:20:44
>> For proof of this, create a file in /tmp, set the schg flag and try
>> remove the file. Try rebooting, and see what happens when something
>> tries to remove it whilst cleaning /tmp on reboot.
>> 142: touch /tmp/foo
>> 143: chflags uchg /tmp/foo
>> 144: rm -f /tmp/foo
>> rm: /tmp/foo: Operation not permitted
>> 145: mv -f /tmp/foo /tmp/bar
>> mv: rename /tmp/foo to /tmp/bar: Operation not permitted
>> 146: touch /tmp/xx
>> 147: mv -f /tmp/xx /tmp/foo
>> mv: rename /tmp/xx to /tmp/foo: Operation not permitted
>> So far so good. But....
>> 148: chflags nouchg /tmp/foo
>> 149: rm /tmp/foo
>> 150: ls /tmp/foo
>> ls: /tmp/foo: No such file or directory
>> I didn't try the super-user version so may be this hole is filled.
>> [Besides, it does say this call is under development:-)]
>> Any way, I have said what I wanted to on this topic so I
>> will shut up now.
> what was your securelevel for this ? if it was > 0, then this is
> a security bug that should have been fixed a long time ago.
from CHFLAGS(2) NetBSD Programmer's Manual CHFLAGS(2)
The ``UF_IMMUTABLE'' and ``UF_APPEND'' flags may be set or unset by ei-
ther the owner of a file or the super-user.
The ``SF_IMMUTABLE'' and ``SF_APPEND'' flags may only be set or unset by
the super-user. They may be set at any time, but normally may only be
unset when the system is in single-user mode. (See init(8) for details.)