How best get rid of SELinux?

[Mike McCarty]

Tom Rivers wrote:
> Mike McCarty wrote:
> 

[snip]
> 
> OK, I see that you are looking at this from an all or nothing approach.  
> I would argue that it isn't always the right decision to throw the baby 
> out with the bath water, even with a computer system.  Just because one 

Argue away.

> Here's something to consider.  If you know a machine is compromised, you 

Considered.

[snip]

>> I believe that ABS attempts to prevent compromise of stability.
>>
> 
> Actually ABS kicks in a split second after the wheels lock up, after 

I know how they work.

[snip]

>> The only truly secure machine is one which is physically
>> secure. Anything else leaves the realm of security, and enters the
>> realm of relative security, which is entirely different, and has
>> cost/benefit considerations.
>>
> 
> Technically speaking, a "physically secure" system isn't secure any more 
> than an "electronically secure" system is.  In both cases the assertion 
> is made that good defenses are in place, but I think you'll be hard 
> pressed to find any security professional on the planet who will give a 
> 100% guarantee even if the system is under lock and key and off the 
> Internet entirely.  That's because someone can always break a window, 
> pick a lock, or hold your loved ones at gunpoint to gain access.

Then you don't understand the meaning of the word "physical security".
What you describe is not a physically secure system.

[snip]

>> (3) Anyone who lives in the relative security realm, as do most
>> of us at least some of the time (I do have absolutely secure machines),
>> must assess the cost/benefit of each security measure he implements.
>>
> 
> I agree completely.
> 
>> Wrong analogy, I think. You might feel differently if you installed
>> an enormous machine drawing electricity from your house wiring,
>> intended to operate a sprinkler system, and the additional load was
>> the cause of the fire. SELinux has its own exploits.
> 
> 
> Well, I think your analogy fails because the person implementing the 
> system should take the power consumption it requires into 
> consideration.  Also, your analogy points to the power consumption being 
> the cause of the problems and that doesn't track with SELinux because it 
> is what's working to prevent problems.

SELinux has been known to reveal unencrypted root passwords to
non-privileged processes. At least one instance is known
where this happened, and would not have happenend had SELinux
not been installed.

> I have been running SELinux for some time and have yet to see a 
> performance problem that can be measured.  It may exist, however I 
> haven't seen anyone who has any metrics on the drain SELinux has on a 
> system.  If you have such information, I would greatly appreciate a 
> link.  I would also appreciate some links to information regarding the 
> SELinux exploits you mention because I haven't heard of any.

Google is your friend. I found quite a few mentioned over at nsa.gov.

>> IMO, trying to mitigate damage is not the proper response. The proper
>> response is to keep backups of important data. The system
>> itself must not be reintroduced.
> 
> 
> As I said earlier, unless you know what caused the system to become 
> compromised, you simply cannot expect to be more secure by restoring any 
> data at all.  If you restore that important data, you will never know if 

Where did I state that as a goal? If I were not already satisfied with
my level of security, I might consider using SELinux more. As it is,
I'm pretty sure any compromise will be a result of browsing or mail.
As such, hopefully the improvement will come to the tool, the exploit
will be plugged, and that will end it.

> it carries a deadly payload, the kind that was never identified when the 

Eh? My text files, PDFs, and so on are deadly payload? I know where they
are, and I routinely check for "unusual permissions", like execute,
on such kinds of files.

> decision to scrap the system was made.  If you do know what caused it, 
> then you can not only be more secure in the future by protecting against 
> the threat, but you can also save a significant amount of down-time and 
> aggravation reloading everything from scratch.

If my system were going down continually, then I would pull the internet
plug.

> Blindly scrapping a system and reloading possibly tainted data as a 
> result is quite frankly an act of ignorant desperation.  Sure you can go 

You use pejorative language, but not an argument. One has to
reload in any case. One does not "blindly reload".

Mike
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