Messages in this thread | | | Date | Thu, 4 Sep 2014 17:43:40 +0100 | From | One Thousand Gnomes <> | Subject | Re: RFC: Tainting the kernel on raw I/O access |
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> > As for the original purpose of taints, I'm not aware of any > > problems with MSR access or port IO causing excessive > > kernel oops reports. Are you?
I'm not. From the bugzilla trends I don't think its a major cause, and we can usually root out the "user with dumb external module" problem already.
> Really? Either one can be used to modify the running kernel (or > microcode), and possibly even destroy hardware.
At least on x86 I would hope not the latter at least on modern systems. So the most irritating thing you can do is probably rootkit the box. It's not as if you can't rootkit a typical distribution shipping Linux system half a dozen other simpler ways than using I/O ports. Besides which once someone has rootkitted your box it won't show the taint anyway !
As a security measure the tainting is next to useless.
As a debug aid it's potentially handy.
> > If there are none I don't think it makes sense. > > > > At least personally I use MSR accesses quite frequently > > for benign purposes. > But how much of that is just reading MSR's, and of the writes, how much > are either debugging or things that the average user isn't ever going to do?
Most of the uses are benign and sensible things like power monitoring tools.
Alan
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