Re: LSM conversion to static interface

Giacomo A. Catenazzi
2007-10-23T09:14:49Z

Jan Engelhardt wrote:
> On Oct 23 2007 07:44, Giacomo Catenazzi wrote:
>>> I do have a pseudo LSM called "multiadm" at
>>> http://freshmeat.net/p/multiadm/ , quoting:
>>> Policy is dead simple since it is based on UIDs. The UID ranges can be
>>> set on module load time or during runtime (sysfs params). This LSM is
>>> basically grants extra rights unlike most other LSMs[1], which is why
>>> modprobe makes much more sense here. (It also does not have to do any
>>> security labelling that would require it to be loaded at boot time
>>> already.)
>> But his is against LSM design (and first agreements about LSM):
>> LSM can deny rights, but it should not give extra permissions
>> or bypass standard unix permissions.
>
> It is just not feasible to add ACLs to all million files in /home,
> also because ACLs are limited to around 25 entries.
> And it is obvious I do not want <prof> to have UID 0, because
> then you cannot distinguish who created what file.
> So the requirement to the task is to have unique UIDs.
> The next logical step would be to give capabilities to those UIDs.
>
> *Is that wrong*? Who says that only UID 0 is allowed to have
> all 31 capability bits turned on, and that all non-UID 0 users
> need to have all 31 capability bits turned off?
>
> So, we give caps to the subadmins (which is IMHO a natural task),
> and then, as per LSM design (wonder where that is written) deny
> some of the rights that the capabilities raised for subadmins grant,
> because that is obviously too much.

Nothing wrong. I only said that it was against (IIRC) the
principle of LSM in kernel (we should only remove capacities).
I've nothing against the changing the design or rules.
It was only a commentary, to be sure that we know what we do ;-)

ciao
cate